九州大学 研究者情報
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梶原 稔尚(かじわら としひさ) データ更新日:2021.06.07

教授 /  工学研究院 化学工学部門 生産システム工学


原著論文
1. 加賀雅文, 藤本憲一朗,梶原稔尚, 薄膜多層被覆電線用クロスヘッドの分配流路設計手法, 成形加工, 32, 8, 2020.08.
2. Yuki Matsuoka, Yasuya Nakayama, Toshihisa Kajiwara, Prediction of shear-thickening of particle suspensions in viscoelastic fluids by direct numerical simulation, Journal of Fluid Mechanics, Vol. 913, 2021.03, [URL].
3. Yasuya Nakayama, Toshihisa Kajiwara, Flow classification and its application to fluid processing, MATEC Web Conference, vol.333, 02001(6), 2021.01.
4. 木村公一, 名嘉山祥也, 梶原稔尚, ダルメージ型スクリュの形状と分配混合性能の相関評価, 日本製鋼所技報, 71, 69-75, 2020.11.
5. Yusuke Fujii, Kengo Higashi, Hiroshi Mizumoto, Masamichi Kamihira, Toshihisa Kajiwara, A bioartificial liver device based on three-dimensional culture of genetically engineered hepatoma cells using hollow fibers, Cytotechnology, 10.1007/s10616-020-00372-0, 72, 2, 227-237, 2020.04, [URL], The bioartificial liver (BAL) device is an extracorporeal liver support system incorporating living hepatocytes. A major problem in BAL device development is to obtain a high number of functional cells. In this study, we focused on a genetically engineered mouse hepatoma cell line, Hepa/8F5, in which elevated liver functions are induced via overexpression of liver-enriched transcription factors activated by doxycycline (Dox) addition. We applied a three-dimensional culture technique using hollow fibers (HFs) to Hepa/8F5 cells. Hepa/8F5 cells responded to Dox addition by reducing their proliferative activity and performing liver-specific functions of ammonia removal and albumin secretion. The functional activities of cells depended on the timing of Dox addition. We also found that Hepa/8F5 cells in the HF culture were highly functional in a low rather than high cell density environment. We further fabricated an HF-type bioreactor with immobilized Hepa/8F5 cells as a BAL device. Although ammonia removal activity of this BAL device was lower than that of the small-scale HF bundle, albumin secretion activity was slightly higher. These results indicated that the BAL device with immobilized Hepa/8F5 cells was highly functional with potential to show curative effects in liver failure treatment..
6. Yuki Matsuoka, Yasuya Nakayama, Toshihisa Kajiwara, Effects of viscoelasticity on shear-thickening in dilute suspensions in a viscoelastic fluid, Soft Matter, 10.1039/c9sm01736d, 16, 3, 728-737, 2020, [URL], We investigate previously unclarified effects of fluid elasticity on shear-thickening in dilute suspensions in an Oldroyd-B viscoelastic fluid using a novel direct numerical simulation based on the smoothed profile method. Fluid elasticity is determined by the Weissenberg number Wi and by viscosity ratio 1 - β = ηp/(ηs + ηp) which measures the coupling between the polymer stress and flow: ηp and ηs are the polymer and solvent viscosity, respectively. As 1 - β increases, while the stresslet does not change significantly compared to that in the β → 1 limit, the growth rate of the normalized polymer stress with Wi was suppressed. Analysis of flow and conformation dynamics around a particle for different β reveals that at large 1 - β, polymer stress modulates flow, leading to suppression of polymer stretch. This effect of β on polymer stress development indicates complex coupling between fluid elasticity and flow, and is essential to understand the rheology and hydrodynamic interactions in suspensions in viscoelastic media..
7. Sakiko Matsushita, Toshihisa Kajiwara, Hiroshi Mizumoto, Expansion and differentiation of human iPS cells in a three-dimensional culture using hollow fibers and separation of the specific population by magnetic-activated cell sorting., Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2019.03.014, 128, 4, 480-486, 2019.10.
8. Yasuya Nakayama, Satoshi Esaki, Kenta Nakao, Toshihisa Kajiwara, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Mixing characteristics of different kneading elements
An experimental study, 33rd International Conference of the Polymer Processing Society, PPS 2017
Proceedings of PPS 2017
33rd International Conference of the Polymer Processing Society - Conference Papers
, 10.1063/1.5121652, 2019.08, [URL], We discuss the melt-mixing characteristics of different geometries of pitched-tip kneading disks (ptKD). Extrusion experiment was performed under the fully-filled state in the kneading zone by controlling the fill lengths for different KDs. We study the variation of the particle size distribution and the rheological response of ABS (acrylonitrilebutadiene-styrene copolymer) caused by melt-mixing. We found that the increase or decrease of the fine and coarse particles depends on the type of KD. Furthermore, the change of the particle size distribution affects the storage modulus at low frequencies. From these results, different mixing characteristics of different KDs are evaluated..
9. K. Sekiyama, S. Yamada, T. Nakagawa, Y. Nakayama, T. Kajiwara, Partially Filled Flow Simulation Using Meshfree Method for High Viscosity Fluid in Plastic Mixer, International Polymer Processing, 34, 2, 279-289, 2019.05.
10. Kazuhide Sekiyama, S. Yamada, T. Nakagawa, Y. Nakayama, T. Kajiwara, Partially filled flow simulation using meshfree method for high viscosity fluid in plastic mixer, International Polymer Processing, 10.3139/217.3727, 34, 2, 279-289, 2019.04, [URL], A novel simulation technique for the flow in plastic mixers based on Element-free Galerkin Method (EFGM) has been developed in this study. To improve the simulation accuracy, a rearrangement” scheme has been employed which eliminates errors caused by the irregular distribution of data points. Through several numerical tests, the new simulation technique has been validated to be applicable to high viscosity fluid flow with enough accuracy. Furthermore, simulation examples for realistic mixers were carried out using the developed technique. From the results, it was found that the developed technique is capable to investigate the relationship between flow behavior inside realistic mixers and operating conditions..
11. Yasuya Nakayama, Takemitsu Hiroki, Toshihisa Kajiwara, Koichi Kimura, Takeuchi Takahide and Hideki Tomiyama, Characterization of melt-mixing in extrusion: finite-time Lyapunov exponent and flow pattern structure, AIP Conf. Proc., 2065, 30032, 2019.02.
12. Yasuya Nakayama, Takemitsu Hiroki, Toshihisa Kajiwara, Koichi Kimura, Takeuchi Takahide, Hideki Tomiyama, Characterization of melt-mixing in extrusion
Finite-time Lyapunov exponent and flow pattern structure, 34th International Conference of the Polymer Processing Society, PPS 2018
Proceedings of PPS-34
34th International Conference of the Polymer Processing Society - Conference Papers
, 10.1063/1.5088290, 2019.02, [URL], We discuss the mixing characteristics of different kneading blocks based on the numerical simulation of non-isothermal polymer melt flow. The distributive and dispersive mixing is assessed by using finite-time Lyapunov exponent and the mean stress during residence. In addition, the flow patterns associated with the different geometry of the mixing elements are quantified by the strain-rate state. Our approach is found to be useful to evaluate essential difference of mixing characteristics between the conventional kneading discs element and pitched-tip kneading discs elements..
13. Yuki Matsuoka, Yasuya Nakayama, Toshihisa Kajiwara, Shear-thickening in a dilute suspension of spheres in a weakly viscoelastic fluid: an approach with a direct numerical simulation, Proceedings of Soft Matter Physics: from the perspective of the essential heterogeneity, 2018.12.
14. Yasuya Nakayama, Hiroki Takemitsu, Satoshi Esaki, Toshihisa Kajiwara, Koichi Kimura, Takeuchi Takahide, Tomiyama Hideki, MIXING CHARACTERISTICS OF DIFFERENT KNEADING ELEMENTS IN A TWIN-SCREW EXTRUDER: A NUMERICAL STUDY AND AN EXPERIMENTAL VERIFICATION, Proceedings of Asian Workshop on Polymer Processing 2018 (AWPP2018), 2018.12.
15. Koichi Kimura, Yasuya Nakayama, Toshihisa Kajiwara, EVALUATION OF DISTRIBUTIVE MIXING PERFORMANCE OF FIN TYPE SCREW FOR A SINGLE SCREW EXTRUDER, Proceedings of Asian Workshop on Polymer Processing 2018 (AWPP2018), 2018.12.
16. Yasuya Nayakaya, Satoshi Esaki, Kenta Nakao, Toshihisa Kajiwara, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Mixing Characteristics of Different Kneading Elements: an Experimental Study, AIP Conf. Proc., 2018.12.
17. Yasuya Namayama, Hiroki Takemitsu, Toshihisa Kajiwara, Koichi Kimura, Takeuchi Takahide, Tomiyama Hideki, Impacts of Pitched Tips of Kneading Element in Twin-Screw Extrusion: Tuning Flow Pattern and Mixing Performance, Proceedings of the Conference on Modelling Fluid Flow (CMFF’18), 2018.09.
18. 木村公一, 富山秀樹, 名嘉山祥也, 梶原稔尚, 単軸押出機のフィン型混練スクリュの分配混合性能評価, Seikei-Kakou, 30, 8, 445-451, 2018.08.
19. Kei Ito, Yasuya Nakayama, Toshihisa Kajiwara, Nonlinear Electrophoresis in the Salt-free Limit, Proceedings of the 7th Pacific Rim Conference on Rheology (PRCR 2018), 2018.06.
20. Koichi Kimura, Hideki Tomiyama, Yasuya Namayama, Toshihisa Kajiwara, Evaluation of Distributive Mixing Performance of Fin Type Screw for Single-Screw Extruder, Proceedings of the Polymer Processing Society 34th Annual Meeting (PPS-34), 2018.05.
21. Yasuya Namayama, Hiroki Takemitsu, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama, Characterization of melt-mixing in extrusion: finite-time Lyapunov exponent and flow pattern structure, Proceedings of the Polymer Processing Society 34th Annual Meeting (PPS-34), 2018.05.
22. Sakiko Matsushita, Toshihisa Kajiwara, Hiroshi Mizumoto, Improving mixing characteristics with a pitched tip in kneading elements in twin-screw extrusion, AIChE J., 64, 4, 1424-1434, 2018.04, [URL].
23. Yasuya Nakayama, Hiroki Takemitsu, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama, Improving mixing characteristics with a pitched tip in kneading elements in twin-screw extrusion, AIChE Journal, 10.1002/aic.16003, 64, 4, 1424-1434, 2018.04, [URL], In twin-screw extrusion, the geometry of a mixing element mainly determines the basic flow pattern, which eventually affects the mixing ability as well as the dispersive ability of the mixing element. The effects of geometrical modification, with both forward and backward pitched tips, of a conventional forward kneading disks element (FKD) in the pitched-tip kneading disks element on the flow pattern and mixing characteristics are discussed. Numerical simulations of fully filled, nonisothermal polymer melt flow in the melt-mixing zone were performed, and the flow pattern structure and the tracer trajectories were investigated. The pitched tips largely affect the inter-disk fluid transport, which is mainly responsible for mixing. These changes in the local flow pattern are analyzed by the distribution of the strain-rate state. The distribution of the finite-time Lyapunov exponent reveals a large inhomogeneity of the mixing in FKD is suppressed both by the forward and backward tips. By the forward tips on FKD, the mixing ability is relatively suppressed compared to FKD, whereas for the backward tips on FKD, the mixing ability is enhanced while maintaining the same level of dispersion efficiency as FKD. From these results, the pitched tips on the conventional KD turn out to be effective at reducing the inhomogeneity of the mixing and tuning the overall mixing performance..
24. Yu Nakano, Shinya Iwanaga, Hiroshi Mizumoto, Toshihisa Kajiwara, Evaluation of hollow fiber culture for large-scale production of mouse embryonic stem cell-derived hematopoietic stem cells, Cytotechnology, 10.1007/s10616-018-0210-z, 1-8, 2018.03, [URL].
25. Hiroshi Mizumoto, Naoki Amimoto, Toru Miyazawa, Hideki Tani, Kaoru Ikeda, Toshihisa Kajiwara, In vitro and ex vivo Functional Evaluation of a Hollow Fiber-type Bioartificial Liver Module Containing ES Cell-derived Hepatocyte-like Cells, Advanced Biomedical Engineering, 10.14326/abe.7.18, 7, 0, 18-27, 2018.01, [URL].
26. Toshihisa Kajiwara, Yasuya Namayama, Hiroki Takemitsu, Satoshi Esaki, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Mixing characteristics of different kneading elements: An experimental study, Proceedings of the Polymer Processing Society 33rd Annual Meeting (PPS-33), 2017.12.
27. 木村公一, 富山秀樹, 名嘉山祥也, 梶原稔尚, 単軸混練スクリュの分配混合性能の評価, 日本製鋼所技報, 68, 110-116, 2017.11.
28. Yasuya Nakayama, Hiroki Takemitsu, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama, Impacts of Pitched Tips of Kneading Element in Twin-Screw Extrusion: Tuning Flow Pattern and Mixing Performance, Proceedings of the Asian Workshop on Polymer Processing 2017 (AWPP2017), 2017.10.
29. Tatsuya Okudaira, Ryohei Yabuta, Hiroshi Mizumoto, Toshihisa Kajiwara, Fabrication of a fiber-type hepatic tissue by bottom-up method using multilayer spheroids, Journal of Bioscience and Bioengineering, 123, 6, 739-747, 2017.06.
30. Tatsuya Okudaira, Ryohei Yabuta, Hiroshi Mizumoto, Toshihisa Kajiwara, Fabrication of a fiber-type hepatic tissue by bottom-up method using multilayer spheroids, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2017.01.002, 123, 6, 739-747, 2017.06, [URL], Liver regenerative medicine, a therapy using cultured hepatocytes or hepatic tissues, has the potential to replace liver transplantation. However, this therapeutic strategy has challenges to overcome, including in construction of the hepatic tissues. As an approach to fabricating functional 3D hepatic tissues, we focused on hepatocyte spheroids, which have high cell density and maintain high liver-specific functions. We employed a bottom-up method using spheroids, arranging hepatocytes and endothelial cells regularly at the time of tissue construction. This enabled a vascular network to be formed within the three-dimensional hepatic tissue. We included NIH/3T3 cells, known to promote vasculature formation by endothelial cells. We fabricated hepatocyte spheroids covered with human umbilical vein endothelial cells (HUVECs) and NIH/3T3 cells (EC-3T3-covered hepatocyte spheroids) and constructed the hepatic tissues by stacking these cell types in hollow fibers. We then performed histological and functional analyses of the resulting hepatic tissues. The hepatic tissues constructed by stacking EC-3T3-covered hepatocyte spheroids showed high liver-specific functions; that is, ammonia removal and albumin secretion. The HUVECs formed endothelial networks. In addition, hypoxia-inducible factor-1α (HIF-1α) expression was suppressed in the hepatic tissue throughout the culture period and the hepatic tissue was sufficiently strong for use in certain analyses and applications. In summary, we fabricated a functional 3D hepatic tissue by the bottom-up method using hepatocyte spheroids covered with HUVECs and NIH/3T3 cells..
31. 梶原 稔尚, 高分子材料の溶融混練シミュレーションと混練性能評価, 日本ゴム協会誌, 89, 12, 355-361, 2016.12.
32. Yasuya Nakayama, Nariyoshi Nishihira, Toshihisa Kajiwara, Hideki Tomiyama, Takahide Takeuchi, Koichi Kimura, Effects of pitched tips of novel kneading disks on melt mixing in twin-screw extrusion, Nihon Reoroji Gakkaishi(Journal of the Society of Rheology, Japan), 44, 5, 281-288, 2016.12.
33. Satoshi Esaki, Kenta Nakao, Yasuya Nakayama, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama, Mixing characteristics of different kneading elements: An experimental study, Proceedings of the 29th International Symposium on Chemical Engineering 2016 (29th ISChE 2016), 2016.12.
34. Hiroki Takemitsu, Yasuya Nakayama, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama, Impacts of mixing elements on mixing characteristics in twin-screw extrusion, Proceedings of the 29th International Symposium on Chemical Engineering 2016 (29th ISChE 2016), 2016.12.
35. Toshihisa Kajiwara, Kunihiro Hirata, Hiroshi Ishida, Motohiro Hiragori, Yasuya Nakayama, Prediction of Mixing Performance for Glass Fiber Dispersion in a Twin-Screw Extruder Using Numerical Simulation, International Workshop on Process Intensification 2016 (IWPI 2016), 2016.09.
36. Toshihisa Kajiwara, Yasuya Nakayama, Hiroki Takemitsu, Satoshi Esaki, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Evaluation of Melt-Mixing Performance in a Twin-Screw Extruder - Experimental Verification -, Proceedings of the XVIIth International Congress on Rheology (ICR2016), 2016.08.
37. Yasuya Nakayama, Tatsunori Masaki, Toshihisa Kajiwara, Strain Mode of General Flow: Characterization and Implications for Flow Pattern Structures, Proceedings of the XVIIth International Congress on Rheology (ICR2016), 2016.08.
38. Tatsuya Okudaira, Naoki Amimoto, Hiroshi Mizumoto, Toshihisa Kajiwara, Formation of three-dimensional hepatic tissue by the bottom-up method using spheroids, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2015.12.019, 122, 2, 213-218, 2016.08, [URL], Liver regenerative medicine has attracted attention as a possible alternative to organ transplantation. To address the challenge of liver regenerative medicine, the development of a construction method has been proposed for liver tissue in vitro with a high cell density and high functionality for transplantation into patients with severe liver failure. In this study, we fabricated highly functional three-dimensional hepatic tissue by a bottom-up method using spheroids. The hepatic tissue was formed by stacking hepatocyte spheroids covered with human umbilical vein endothelial cells (HUVECs). Hepatic tissue constructs were evaluated for cell survival, liver-specific functions, and histologically. As a result, we identified improvements in liver-specific functions (ammonia removal and albumin secretion) and cell survival. In addition, HUVECs were regularly distributed at every 100 μm within the tissue, and live cells were present within the whole tissue construct throughout the culture period. In summary, we successfully fabricated highly functional hepatic tissue by the bottom-up method using HUVEC-covered hepatocyte spheroids..
39. Toshihisa Kajiwara, Yasuya Nakayama, Hiroki Takemitsu, Satoshi Esaki, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Melt-Mixing by Pitched-Tip Kneading Disks in a Twin-Screw Extruder - Experimental Verification -, Proceedings of the Polymer Processing Society 32nd Annual Meeting (PPS-32), 2016.07.
40. Yasuya Nakayama, Toshihisa Kajiwara, Tatsunori Masaki, Strain mode of general flow
Characterization and implications for flow pattern structures, AIChE Journal, 10.1002/aic.15228, 62, 7, 2563-2569, 2016.07, [URL], Understanding the mixing capability of mixing devices based on their geometric shape is an important issue both for predicting mixing processes and for designing new mixers. The flow patterns in mixers are directly connected with the modes of the local strain rate, which is generally a combination of elongational flow and planar shear flow. We develop a measure to characterize the modes of the strain rate for general flow occurring in mixers. The spatial distribution of the volumetric strain rate (or non-planar strain rate) in connection with the flow pattern plays an essential role in understanding distributive mixing. With our measure, flows with different types of screw elements in a twin-screw extruder are numerically analyzed. The difference in flow pattern structure between conveying screws and kneading disks is successfully characterized by the distribution of the volumetric strain rate. The results suggest that the distribution of the strain rate mode offers an essential and convenient way for characterization of the relation between flow pattern structure and the mixer geometry..
41. Yasuya Nakayama, Tatsunori Masaki, Toshihisa Kajiwara, Strain Mode of General Flow: Characterization and Implications for Flow Pattern Structures, AIChE J., 62, 7, 2563-2569, 2016.06.
42. Tatsuya Okudaira, Naoki Amimoto, Hiroshi Mizumoto, Toshihisa Kajiwara, Formation of three-dimensional hepatic tissue by the bottom-up method using spheroids
, Journal of Bioscience and Bioengineering
, 2016.01.
43. Yasuya Nakayama, Nariyoshi Nishihira, Toshihisa Kajiwara, Hideki Tomiyama, Takahide Takeuchi, Koichi Kimura, Effects of pitched tips of novel kneading disks on melt mixing in twin-screw extrusion, Nihon Reoroji Gakkaishi, 10.1678/rheology.44.281, 44, 5, 281-288, 2016.01, [URL], In mixing highly viscous materials, like polymers, foods, and rubbers, the geometric structure of the mixing device is a determining factor for the quality of the mixing process. In pitched-tip kneading disks (ptKD), a novel type of mixing element, based on conventional kneading disks (KD), the tip angle is modified to change the channel geometry as well as the drag ability of KD. We discuss the effects of the tip angle in ptKD on mixing characteristics based on numerical simulation of the flow in the melt-mixing zone under different feed rates and a screw rotation speed. It turns out that the passage of fluid through the high-stress regions increases in ptKD compared to conventional KD regardless of the directions and sizes of the tip angle, while the fluctuation in residence time stays at the same level as the conventional KD. Furthermore, pitched tips of backward direction increase the mean applied stress on the fluid elements during its residence in the melt-mixing zone, suggesting the enhancement of dispersive mixing quality in ptKD. These understandings of the role of the tip angle on KD can give a basic guide in selecting and designing suitable angle parameters of ptKD for different mixing purposes..
44. Toshihisa Kajiwara, Yasuya Nakayama, Hiroki Takemitsu, Satoshi Esaki, Takahide Takeuchi, Koichi Kimura, Hideki Tomiyama, Melt-mixing by pitched-tip kneading disks in a twin-screw extruder
, Proceedings of Asian Workshop on Polymer Processing 2015 (AWPP2015)
, 2015.12.
45. 正木辰典, 名嘉山 祥也, 梶原 稔尚, 力学的視点からのフィラー分散に関する基礎的理解, Seikei-Kakou, 27, 12, 533-539, 2015.12.
46. Kunihiro Hirata, Hiroshi Ishida, Motohiro Hiragori, Yasuya Nakayama, Toshihisa Kajiwara, Prediction of fiber dispersion for glass fiber reinforced plastics in a twin-screw extruder using flow simulation, Proceedings of Conference on Modelling Fluid Flow (CMFF’15), 2015.09.
47. Kunihiro Hirata, Hiroshi Ishida, Motohito Hiragoori, Yasuya Nakayama, Toshihisa Kajiwara, Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements, AIP Conf. Proc., 1664, 20009, 2015.06.
48. Yasuya Nakayama, Tatsunori Masaki, Toshihisa Kajiwara, Strain mode of general flow: characterization and implication to mixing
, Proceedings of the Polymer Processing Society 31st Annual Meeting (PPS-31)
, 2015.06.
49. Kunihiro Hirata, Hiroshi Ishida, Motohiro Hiragori, Yasuya Nakayama, Toshihisa Kajiwara, Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements, 30th International Conference of the Polymer Processing Society, PPS 2014
Proceedings of PPS-30
The 30th International Conference of the Polymer Processing Society - Conference Papers
, 10.1063/1.4918389, 2015.05, [URL], In the kneading of glass-fiber-reinforced plastics by twin-screw extrusion, the use of a backward-mixing screw (BMS) element for melt mixing has been found to be effective in dispersing glass-fiber bundles. In this study, we use the computational fluid dynamics (CFD) to study the mechanism of dispersion by a BMS element for glass fiber bundles. The result of CFD for a BMS and a forward kneading disk (FKD) reveals that the melt mixing by a BMS is highly effective to act the required stress on overall resin. In addition, there is a good correlation between the incidence of undispersed glass-fiber bundles measured experimentally and the minimum value of distribution of the time-integrated stress calculated numerically. On the basis of the above results, we propose a method to predict the operating conditions in which the incident probability of undispersed glass-fiber bundles and thermal degradation are controlled..
50. Toshihisa Kajiwara, A study on composite technology in processing of polymers and glasses, Nihon Reoroji Gakkaishi, 10.1678/rheology.43.119, 43, 5, 119-124, 2015.01, [URL], The composite technology is very important for production of high-functional or high-quality materials and products. We have studied the composite technology in processing of polymers and glasses. In this paper, I mainly present the research topics of mixing process of polymeric materials and multi-layered process of polymer films. For the mixing process of polymeric materials, we have developed the computer simulation techniques to predict the materials behavior in a twin-screw extruder and have proposed the methods to evaluate the mixing performance in melt mixing based on the simulation results. Such techniques and methods were applied to the melt mixing in engineering problems. For multilayered process of polymer films, we have developed the simulation techniques of multi-layered flow for viscoelastic fluids and discussed the unstable problem and encapsulation phenomena at interface from the case studies considering die configurations, rheological properties, etc. The neck-in phenomena of multi-layered film could be also understood from simulation results in a die. We also studied the method to evaluate viscoelasticity of interfacial layer for multilayered film using the parallel plate rheometer experimentally. We proposed the non-stick length of interface as an evaluation index. For processing of glasses using polymer-inorganic composites, we proposed processing method to give functions to glass products by using the formable polymer-inorganic composit as a precursor..
51. Kunihiro Hirata, Hiroshi Ishida, Motohito Hiragohri, Yasuya Nakayama, Toshihisa Kajiwara, Prediction of Glass Fiber Dispersion in a Twin-Screw Extruder Using a Three-Dimensional Flow Simulation, Proceedings of Asian Workshop on Polymer Processing 2014 (AWPP2014), 2014.11.
52. Kunihiro Hirata, Hiroshi Ishida,Motohito Hiragohri, Yasuya Nakayama and Toshihisa Kajiwara, Effectiveness of a backward mixing screw element for glass fiber dispersion in a twin-screw extruder, Polymer Engineering & Science, 54, 9, 2005-2012, 2014.09.
53. Kunihiro Hirata, Hiroshi Ishida, Motohito Hiragohri, Yasuya Nakayama, Toshihisa Kajiwara, Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements, Proceedings of the Polymer Processing Society 30th Annual Meeting (PPS-30), 2014.06.
54. 鷲崎 俊朗, 梶原 稔尚, 名嘉山 祥也, カップの圧縮成形解析と厚み分布をもつ幅広な円盤状シートによる成形荷重の低減, 高分子論文集, 71, 3, 89-97, 2014.03.
55. Toshiro Washizakj, Toshihisa Kajiwara, Yasuya Nakayama, Numerical analysis of compression molding for cups and reduction of forming load by using circular sheets having a thickness distribution, KOBUNSHI RONBUNSHU, 10.1295/koron.71.89, 71, 3, 89-97, 2014.03, [URL], A numerical analysis program of compression molding for cups has been developed and the method which reduces the forming load was simulated. It was found that the initial shape of the melted object affected the forming load and the forming load for a wide circular sheet having thickness distribution was lower than that for a cylindrical melt lump. We could also confirmed that the blank holder had an important effect to prevent from the dragging of a melted object into the core during the compression process. The seal part of cup was filled with melted resin in a comparatively earlier stage of compression compared with the case of using a melt lump. We could show that a wide circular sheet having a thickness distribution needs a lower formina load..
56. Toshiro Washizaki, Toshihisa Kajiwara, Yasuya Nakayama, Erratum
Numerical analysis of compression molding for cups and reduction of forming load by using circular sheets having a thickness distribution (Kobunshi Ronbunshu (2014) 71 (89-97)), KOBUNSHI RONBUNSHU, 10.1295/koron.71.261, 71, 5, 2014.01, [URL].
57. Toshihisa Kajiwara, Kazumori Funatsu, Hiroyuki Ijima, Kohji Nakazawa, Hiroshi Mizumoto, Naoki Amimoto, Kaoru Morimura, Hepatic differentiation of ES cells and its quantitative analysis in HF/organoid culture
, Proceedings of The 26th International Symposium on Chemical Engineering
, 2013.12.
58. Toshihisa Kajiwara, Hiroshi Mizumoto, Naoki Amimoto, Yuka Shidahara, Ken Yamada, Shinya Iwanaga, Hematopoietic differentiation of ES cells inside hollow fibers
, Proceedings of The 26th International Symposium on Chemical Engineering
, 2013.12.
59. Toshihisa Kajiwara, Hiroshi Mizumoto, Naoki Amimoto, Tatsuya Okudaira, Formation of a three-dimensional hepatic tissue by stacking endothelial cellcovered hepatocyte spheroids
, Proceedings of The 26th International Symposium on Chemical Engineering
, 2013.12.
60. Toshihisa Kajiwara, Kazumori Funatsu, Hiroyuki Ijima, Koji Nakazawa, Hiroshi Mizumoto, Naoki Amimoto, The functional evaluation of a hollow fiber type bioartificial liver module immobilizing ES cell-derived hepatic cells
, Proceedings of the 2013 Joint of Japan/Taiwan/Korea Chemical Engineering Conference
, 2013.11.
61. Toshihisa Kajiwara, Kazumori Funatsu, Hiroyuki Ijima, Kohji Nakazawa, Hiroshi Mizumoto, Naoki Amimoto, Kaoru Morimura, Quantitative analysis of hepatic cells derived from ES cells in HF/organoid culture
, Proceedings of the 2013 Joint of Japan/Taiwan/Korea Chemical Engineering Conference
, 2013.11.
62. Toshihisa Kajiwara, Kazumori Funatsu, Hiroyuki Ijima, Kohji Nakazawa, Hiroshi Mizumoto, Naoki Amimoto, Kaoru Morimura, Quantitative analysis of hepatic cells derived from ES cells in HF/organoid culture
, Proceedings of the 2013 Joint of Japan/Taiwan/Korea Chemical Engineering Conference
, 2013.11.
63. Toshihisa Kajiwara, Hiroshi Mizumoto, Naoki Amimoto, Tatsuya Okudaira, Fabrication of a functional hepatic tissue by stacking endothelial cellcovered hepatocyte spheroids
, Proceedings of the 2013 Joint of Japan/Taiwan/Korea Chemical Engineering Conference
, 2013.11.
64. Toshihisa Kajiwara, Hiroshi Mizumoto, Yuka Shidahara, Ken Yamada, Shinya Iwanaga, Generation of hematopoietic cells from embryonic stem cells inside hollow fibers
, Proceedings of the 2013 Joint of Japan/Taiwan/Korea Chemical Engineering Conference
, 2013.11.
65. Toshihisa Kajiwara, Yasuya Nakayama, Motohiro Hiragohri, Hiroshi Ishida, Kunihiro Hirata, Efectiveness of a backward mixing screw element for glass fiber dispersion in a twin-screw extruder, Polymer Engineering & Science, 10.1002/pen.23752, 2013.09.
66. K. Hirata, H. Ishida, M. Hiragohri, Y. Nakayama, and T. Kajiwara, Experimental Assessment of Dispersion Failure of Glass Fiber Reinforced Plastics in a Twin Screw Extruder, International Polymer Processing, 28, 4, 368-375, 2013.08.
67. Kunihiro Hirata, H. Ishida, M. Hiragohri, Y. Nakayama, T. Kajiwara, Experimental assessment of dispersion failure of glass fiber reinforced plastics in a twin screw extruder, International Polymer Processing, 10.3139/217.2704, 28, 4, 368-375, 2013.08, [URL], To investigate the conditions necessary for glass fiber bundle dispersion in the polymer compounding process, we developed a method for experimentally quantifying dispersion failure in this study. We employed a co-rotating twin-screw extruder in our experiment and investigated the dependence of frequency of occurrence of dispersion failure on screw configurations (a forward kneading disk (FKD) and a backward mixing screw (BMS) with different screw configurations), throughput (Q), and screw speed (Ns). From our experiments, we found that increasing the production rate promotes the occurrence of dispersion failure when a FKD is used. Dispersion failure is markedly suppressed when a BMS is used. We thus found that the production rate could be increased by using a BMS with a large length-to-diameter (L/D) ratio..
68. Toshihisa Kajiwara, Yasuya Nakayama, Quantifying hierarchical mizture quality in polymer composite materials: structure and inhomogeneity in multiple scales, Vol54, 1227-1233, 2013.02.
69. Yasuya Nakayama, Toshihisa Kajiwara, Quantifying hierarchical mixture quality in polymer composite materials
Structure and inhomogeneity in multiple scales, polymer, 10.1016/j.polymer.2012.12.056, 54, 3, 1227-1233, 2013.02, [URL], Mixture quality plays a crucial role in the physical properties of multi-component immiscible polymer mixtures including nanocomposites and polymer blends. Such complex mixtures are often characterized by hierarchical internal structures, which have not been accounted for by conventional mixture quantifications. We propose a way to characterize the mixture quality of complex mixtures with hierarchical structures. Starting from a concentration field, which can be typically obtained from TEM/SEM images, the distribution of the coarse-grained concentration is analyzed to obtain the scale-dependent inhomogeneity of a mixture. The hierarchical nature of a mixture is characterized by multiple characteristic scales of the scale-dependent inhomogeneity. We demonstrate how the proposed method works to characterize sizes and distributions in different dispersions. This method is generally applicable to various complex mixtures..
70. 梶原 稔尚, 水本 博, 船津和守, 人工肝臓
, 日本人工臓器学会
, 291-307, 2012.12.
71. Yasuya Nakayama, Kiyoyasu Kataoka, Toshihisa Kajiwara, Dynamic shear responses of polymer-polymer interfaces, Nihon Reoroji Gakkaishi, 10.1678/rheology.40.245, 40, 5, 245-252, 2012.12, [URL], In multi-component soft matter, interface properties often play a key role in determining the properties of the overall system. The identification of the internal dynamic structures in non-equilibrium situations requires the interface rheology to be characterized. We have developed a method to quantify the rheological contribution of soft interfaces and evaluate the dynamic modulus of the interface. This method reveals that the dynamic shear responses of interfaces in bilayer systems comprising polypropylene and three different polyethylenes can be classified as having hardening and softening effects on the overall system: a interface between linear long polymers becomes more elastic than the component polymers, while large polydispersity or long-chain-branching of one component make the interface more viscous. We find that the chain lengths and architectures of the component polymers, rather than equilibrium immiscibility, play an essential role in determining the interface rheological properties..
72. Yasuya Nakayama, Kiyoyasu Kataoka, and Toshihisa Kajiwara, Dynamic shear responses of polymer-polymer interfaces, Nihon Reoroji Gakkaishi (Journal of the Society of Rheology, Japan), 2012.07.
73. Hiroshi IKEDA, Shigeru FUJINO, Toshihisa KAJIWARA, Fabrication of Au Nanoparticles Doped Bulk Silica Glass by Use of SiO2-PVA Nanocomposite, Journal of the Ceramic Society of Japan, Vol.120, pp.238-242, 2012.06.
74. 水本博、梶原稔尚, 中空糸を用いた胚性幹細胞の肝分化誘導プロセス開発とバイオ人工肝臓への応用, , Vol.37, pp.125-131, 2012.05.
75. Hiroshi Mizumoto, Shunsuke Hayashi, Kinya Matsumoto, Kaoru Ikeda, Tomoaki Kusumi, Masakazu Inamori, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, Evaluation of a hybrid artificial liver module based on a spheroid culture system of embryonic stem cell-derived hepatic cells, Cell Transplantation, 10.3727/096368911X605321, 21, 2-3, 421-428, 2012.04, [URL], Hybrid artificial liver (HAL) is an extracorporeal circulation system comprised of a bioreactor containing immobilized functional liver cells. It is expected to not only serve as a temporary liver function support system, but also to accelerate liver regeneration in recovery from hepatic failure. One of the most difficult problems in developing a hybrid artificial liver is obtaining an adequate cell source. In this study, we attempt to differentiate embryonic stem (ES) cells by hepatic lineage using a polyurethane foam (PUF)/spheroid culture in which the cultured cells spontaneously form spherical multicellular aggregates (spheroids) in the pores of the PUF. We also demonstrate the feasibility of the PUF-HAL system by comparing ES cells to primary hepatocytes in in vitro and ex vivo experiments. Mouse ES cells formed multicellular spheroids in the pores of PUF. ES cells expressed liver-specific functions (ammonia removal and albumin secretion) after treatment with the differentiation-promoting agent, sodium butyrate (SB). We designed a PUF-HAL module comprised of a cylindrical PUF block with many medium-flow capillaries for hepatic differentiation of ES cells. The PUF-HAL module cells expressed ammonia removal and albumin secretion functions after 2 weeks of SB culture. Because of high proliferative activity of ES cells and high cell density, the maximum expression level of albumin secretion function per unit volume of module was comparable to that seen in primary mouse hepatocyte culture. In the animal experiments with rats, the PUF-HAL differentiating ES cells appeared to partially contribute to recovery from liver failure. This outcome indicates that the PUF module containing differentiating ES cells may be a useful biocomponent of a hybrid artificial liver support system..
76. Hiroshi MIZUMOTO, Shunsuke HAYASHI, Kinya MATSUMOTO, Kaoru IKEDA, Tomoaki KUSUMI, Masakazu INAMORI, Kohji NAKAZAWA, Hiroyuki IJIMA, Kazumori FUNATSU, Toshihisa KAJIWARA, Evaluation of a Hybrid Artificial Liver Module Based on a Spheroid Culture System of Embryonic Stem Cell-Derived Hepatic Cells, Cell Transplantation, Vol.21, pp421-428, 2012.02.
77. Hiroshi Ikeda, Shigeru Fujino, Toshihisa Kajiwara, Fabrication of Au nanoparticles doped bulk silica glass by use of SiO 2-PVA nanocomposite, Journal of the Ceramic Society of Japan, 10.2109/jcersj2.120.238, 120, 1402, 238-242, 2012, [URL], Au doped silica glass was fabricated by use of SiO2PVA nanocomposite. Porous inorganicorganic nanocomposite, which has nanometer sized pores, was prepared from fumed silica and poly(vinyl alcohol) (PVA). HAuCl 4 solution impregnated the porous SiO2PVA nanocomposite, and then Au ion was reduced and Au metal nanoparticles were formed by heat treatment. After combustion of PVA, SiO2 nanoparticles were sintered and Au particle growth were occurred above 800°C, and then bulk Au nanoparticles doped silica glasses were obtained by sintering at 1100°C for 6 h in air. Au particle size and concentration in the silica glass are increased with the concentration of the HAuCl4 solution. Au doped bulk silica glass was obtained without gold escape from the surface..
78. Toshihisa KAJIWARA and Yasuya NAKAYAMA, Capturing the Efficiency of a Melt-Mixing Process for Polymer Processing, Journal of Chemical Engineering of Japan, Vol.44,pp831-839, 2011.11.
79. Toshihisa Kajiwara, Yasuya Nakayama, Capturing the efficiency of a melt-mixing process for polymer processing, JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 10.1252/jcej.11we081, 44, 11, 831-839, 2011.11, [URL], Polymer blends and composite materials are often produced by a melt-mixing process using equipment specially designed to mix high-viscosity fluids during laminar flow. The melt-mixing process can be classified into distributive and dispersive mixing. Distributive mixing includes stretching and folding of fluid elements and rearrangement of dispersed materials. Dispersive mixing is the size reduction of filler aggregates and/or liquid droplets in a matrix fluid. In order to optimize the design of a melt-mixing equipment, the evaluation of distributive and dispersive mixing is essential. In this paper, we consider fundamental aspects of melt-mixing, and experimental and computational approaches that have been reported in the literatures. Experimental observation of melt-mixing, by and large, provides rather limited information on the mixing process inside of equipment. Although a mixed material can be obtained under specified conditions and its physical properties can be directly measured, it is difficult for the mixing mechanism behind the final result to be inferred. Computational fluid dynamics complements this situation. Numerical simulation of a mixing process provides a non-invasive and detailed data in a equipment so that the quantitative measures for distributive and dispersive mixing can be obtained. We consider various quantitative measures that have been previously proposed to characterize distributive and dispersive mixing..
80. Naoki Amimoto, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, An evaluation of the utility of the hepatic differentiation method using hollow fiber/organoid culture for the development of a hybrid artificial liver device, Biochemical Engineering Journal, Vol.56,pp69-74, 2011.09.
81. Naoki Amimoto, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, An evaluation of the utility of the hepatic differentiation method using hollow fiber/organoid culture for the development of a hybrid artificial liver device, Biochemical Engineering Journal, 10.1016/j.bej.2011.05.010, 56, 1-2, 69-74, 2011.09, [URL], To put the hybrid artificial liver (HAL) using cultured hepatocytes into practical use, it is necessary to develop a high-performance artificial liver device. We developed a novel hollow fiber (HF)/organoid culture method to induce the differentiation of pluripotent stem cells into hepatocytes. In this study, we compared the results of the hepatic differentiation using the HF/organoid culture with those using monolayer culture to evaluate its utility as a hepatic differentiation method. In both cell cultures, ES cells showed high proliferative activity immediately after cell seeding. The up-regulation of hepatocyte-specific markers such as albumin (ALB), carbamoyl phosphate synthetase 1 (CPS-1) and tryptophan 2,. 3-dioxygenase (TDO) were observed as the culture progressed, and the expression of liver-specific functions such as the removal of ammonia and albumin secretion were detected after about 2 weeks of the hepatic differentiation induction in the HF/organoid culture. However, the results were not observed in the monolayer culture. In conclusion, the HF/organoid culture method has promise as an effective tool for the differentiation of ES cells into hepatocytes..
82. Hiroshi Ikeda, Shigeru Fujino, Toshihisa Kajiwara, Fabrication of micropatterns on silica glass by a room-temperature imprinting method, Journal of the American Ceramic Society, 10.1111/j.1551-2916.2010.04368.x, 94, 8, 2319-2322, 2011.08, [URL], A nanocomposite was prepared from fumed silica and PVA. Investigation of the morphology of the composite by TEM and electron energy-loss spectroscopy reveals that the nanocomposite consists of homogeneously dispersed SiO 2 nanoparticles and PVA. Micropatterns on the nanocomposite were fabricated by room-temperature imprinting. Micropatterned silica glass was obtained by sintering the nanocomposite at 1100°C in air..
83. Naoki Amimoto, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, Hepatic differentiation of mouse embryonic stem cells and induced pluripotent stem cells during organoid formation in hollow fibers, Tissue Engineering - Part A, 10.1089/ten.tea.2010.0689, 17, 15-16, 2071-2078, 2011.08, [URL], We have focused on pluripotent stem cells as a potential source of a hybrid-type artificial liver (HAL) and tried to develop a method for differentiating the pluripotent stem cells into cells of a hepatic lineage. In this study, we investigated the hepatic differentiation of mouse embryonic stem (ES) cells and induced pluripotent stem (iPS) cells by applying hollow fiber (HF)/organoid culture method, in which cultured cells form a cellular aggregate called an "organoid" in the lumen of the HF. ES and iPS cells were injected into HFs to induce organoid formation, and cells were cultured. To induce hepatic differentiation, we added differentiation-promoting agents to the culture medium. The expression levels of differentiation-related genes were up-regulated, with cell proliferation and organoid formation inside HFs. Since we were able to achieve a high cell density in culture, the maximum levels of liver-specific functions per unit volume in the differentiating ES and iPS cells reached a level comparable to or better than that of primary mouse hepatocytes. In conclusion, ES and iPS cells have the potential to be a cell source for a HAL, and the HF/organoid culture method, therefore, has promise as a basic technology for the development of a HAL..
84. Naoki Amimoto, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, Hepatic Differentiation of Mouse Embryonic Stem Cells and Induced Pluripotent Stem Cells During Organoid Formation in Hollow Fibers, Tissue Engineering Part A, Vol.17,pp.2071-2078, 2011.05.
85. S.Fujino, S.Inaba, T.Kajiwara and K.Sakai, Non-contact measurement of the viscosity of a B2O3 melt using electric field tweezers, Journal of the Society of Rheology, Vol.39,pp49-54, 2011.02.
86. H.Ikeda, S.Fujino and T.Kajiwara, Fabrication of micropatterns on silica glass by a room-temperature imprinting method, Journal of American Ceramic Society, Vol.94,No.8,pp2319-2322, 2011.02.
87. Yasuya Nakayama, Eiji Takeda, Takashi Shigeishi, Hideki Tomiyama, Toshihisa Kajiwara, Melt-mixing by novel pitched-tip kneading disks in a co-rotating twin-screw extruder, Chemical Engineering Science, Vol.66, No.1, pp.103-110, 2011.01.
88. Hiroshi IKEDA, Shigeru FUJINO and Toshihisa KAJIWARA, Preparation of SiO2–PVA Nanocomposite and Monolithic Transparent Silica Glass by Sintering, Journal of Ceramic Society of Japan, Vol.119,No1385, pp.65-69, 2011.01.
89. Yasuya Nakayama, Eiji Takeda, Takashi Shigeishi, Hideki Tomiyama, Toshihisa Kajiwara, Melt-mixing by novel pitched-tip kneading disks in a co-rotating twin-screw extruder, Chemical Engineering Science, 10.1016/j.ces.2010.10.022, 66, 1, 103-110, 2011.01, [URL], Melt-mixing in twin-screw extruders is a key process in the development of polymer composites. Quantifying the mixing performance of kneading elements based on their internal physical processes is a challenging problem. We discuss melt-mixing by novel kneading elements called "pitched-tip kneading disk (ptKD)". The disk-stagger angle and tip angle are the main geometric parameters of the ptKDs. We investigated four typical arrangements of the ptKDs, which are forward and backward disk-staggers combined with forward and backward tips. Numerical simulations under a certain feed rate and screw revolution speed were performed, and the mixing process was investigated using Lagrangian statistics. It was found that the four types had different mixing characteristics, and their mixing processes were explained by the coupling effect of drag flow with the disk staggering and pitched-tip and pressure flows, which are controlled by operational conditions. The use of a pitched-tip effectively controls the balance of the pressurization and mixing ability..
90. Hiroshi Ikeda, Shigeru Fujino, Toshihisa Kajiwara, Preparation of SiO2-PVA nanocomposite and monolithic transparent silica glass by sintering, Journal of the Ceramic Society of Japan, 10.2109/jcersj2.119.65, 119, 1385, 65-69, 2011.01, [URL], We present a procedure for fabricating transparent silica glass that involves the sintering of green bodies prepared from an inorganic-organic nanocomposite. The nanocomposite was prepared from fumed silica and poly(vinyl alcohol) (PVA). We investigated the SiO2-PVA nanocomposite by Fourier transform infrared spectrometry (FT-IR) measurement, transmission electron microscopy and electron energy-loss spectroscopy, and the results revealed homogeneously dispersed SiO2 nanoparticles and PVA. We examined the relationship between the pH and ζ potential of the SiO2 suspension and the formability of the SiO2-PVA nanocomposite. Formability of the SiO2-PVA nanocomposite was dependent on the pH of the SiO2 suspension, and a monolithic SiO2-PVA nanocomposite without cracks was obtained using a SiO2 suspension at around the isoelectric point (pI). By sintering the SiO2-PVA nanocomposite in air at 1100°C, monolithic transparent silica glass was obtained with no cracks. The glass is highly transparent from the ultraviolet to the visible region..
91. Shigeru Fujino, Seiji Inaba, Toshihisa Kajiwara, Keiji Sakai, Noncontact measurement of viscosity of B2O3 melt using electric-field tweezers, Nihon Reoroji Gakkaishi, 10.1678/rheology.39.49, 39, 1-2, 49-54, 2011, [URL], We propose a novel noncontact method for measuring the viscosity of high-temperature glass melt using a smallamount of sample. This method combines the electric-field tweezers system developed for measuring the local anddynamic surface properties of soft condensed materials and the hot-thermocouple technique for in situ observation andmeasurement of high-temperature liquids. The viscosity of B2O3 melt was measured in the temperature range of 873to 1473 K. The temperature dependence of the viscosity presented in this work is in reasonable agreement with thatreported in the references..
92. T. JOZAKI, K. AOKI, H. MIZUMOTO, T. KAJIWARA, In vitro reconstruction of a three-dimensional mouse hematopoietic microenvironment in the pore of polyurethane foam, Cytotechnology, Vol.62, No.6, pp.531-537, 2010.12.
93. Tadasu Jozaki, Kentaro Aoki, Hiroshi Mizumoto, Toshihisa Kajiwara, In vitro reconstruction of a three-dimensional mouse hematopoietic microenvironment in the pore of polyurethane foam, Cytotechnology, 10.1007/s10616-010-9302-0, 62, 6, 531-537, 2010.12, [URL], Hematopoietic stem cells exist in specific niches in the bone marrow, and generate either more stem cells or differentiated hematopoietic progeny. In such microenvironments, cell-cell and cell-matrix interactions are as important as soluble factors such as cytokines. To provide a similar environment for in vitro studies, a three-dimensional culture technique is necessary. In this manuscript, we report the development of a three-dimensional culture system for murine bone marrow mononuclear cells (mBMMNCs) using polyurethane foam (PUF) as a scaffold. The mBMMNCs were inoculated into two kinds of PUF disks with different surface properties, and cultured without exogenous growth factors. After seeding the inside of the PUF pores with mBMMNCs, PUF disks were capable of supporting adherent cell growth and continuous cell production for up to 90 days. On days 21-24, most nonadherent cells were CD45 positive, and some of the cells were of the erythroid type. From comparisons of the cell growth in each PUF material, the mBMMNC culture in PUF-W1 produced more cells than the PUF-R4 culture. However, the mBMMNC culture in PUF-W1 had no advantages over PUF-R4 with regard to the maintenance of immature hematopoietic cells. The results of scanning electron microscopy and colony-forming assays confirmed the value of the different three dimensional cultures..
94. Hideki YOSHIDA,Shigeru FUJINO,Toshihisa KAJIWARA, Afterglow luminance property of phosphorescent phosphor SrAl2O4:Eu2+,Dy3+-glass composites, Journal of the Ceramic Society of Japan, Vol.118, No.1381, pp.784-787, 2010.09.
95. Hideki YOSHIDA,Hisao ABE,Toshitsugu TAGURI,Fumihiko OHASHI,Shigeru FUJINO,Toshihisa KAJIWARA, Antimicrobial effect of porcelain glaze with silver-cray antimicrobial agent, Journal of the Ceramic Society of Japan, Vol.118, No.1379, pp.571-574, 2010.07.
96. Hideki Yoshida, Hisao Abe, Toshitsugu Taguri, Fumihiko Ohashi, Shigeru Fujino, Toshihisa Kajiwara, Antimicrobial effect of porcelain glaze with silver-clay antimicrobial agent, Journal of the Ceramic Society of Japan, 10.2109/jcersj2.118.571, 118, 1379, 571-574, 2010.07, [URL], Antimicrobial activities of porcelain glazes with antimicrobial agents made of clay minerals intercalated with silver chelate and the effect of additives to the antimicrobial agents on those activities were investigated. The glazes with 10 mass% antimicrobial agents, fired at 1573K in a reducing atmosphere, showed negative antimicrobial activities. On the other hand, the antimicrobial activities of the glazes with 110 mass% of the agents fired in an oxidizing atmosphere were positive. The glaze with an agent doped with Zr had a high antimicrobial activity by adding only 0.2 mass% of the agent, which included only 0.008 mass% Ag in the glaze. Wavelength-dispersive X-ray fluorescence, used for ingredient analysis, showed that the negative activity resulted from the disappearance of the Ag in the glaze fired in the reducing atmosphere..
97. Masakazu Inamori, Hiroshi Mizumoto, Toshihisa Kajiwara, Investigation of medium perfusion through scaffold-free tissue constructs using endothelial cell-covered spheroids in vitro, Biochemical Engineering Journal, 10.1016/j.bej.2010.04.004, 50, 3, 116-121, 2010.07, [URL], A scaffold-free tissue construct was formed by assembling endothelial cell-covered spheroids, and medium perfusion through the tissue construct was investigated using hydrostatic pressure-driven culture circuit. Primary rat hepatocyte spheroids covered by human umbilical vein endothelial cells (HUVECs) were assembled in culture chambers with a cylindrical culture space of 2 mm in diameter, and then medium was perfused through the assembled spheroids for 48 h. The medium flow rate through the culture chamber was measured over the perfusion culture time, which decreased during the first several hours, then increased or remained low depending on the amount of spheroids in the culture chamber. Histochemical analyses showed single tissue construct formation by spheroid fusion when cultured from 2 × 105 nuclei spheroids, with the loss of boundaries between the spheroids. Moreover, a viable cell region was found at the center of the tissue construct in several locations. Poor adhesion was found between spheroids cultured from 4 × 105 nuclei spheroids. The total nuclei density in cultured tissue constructs was estimated to be about half of that in HUVEC-covered hepatocyte spheroids. This study demonstrated the possibility of medium perfusion through scaffold-free tissue constructs by assembling endothelial cell-covered spheroids, promising for a large tissue construct culture in vitro..
98. T. JOZAKI, K. AOKI, H. MIZUMOTO, T. KAJIWARA, Continuous Cell Production from Three Dimensional Hematopoietic Microenvironment in Polyurethane Foam, Animal Cell Technology: Basic & Applied Aspects,Proceedings of the 21st Annual and International Meeting of the Japanese Association for Animal Cell Technology, Vol.16,pp.89-94, 2010.06.
99. M. INAMORI, H. MIZUMOTO, T. KAJIWARA, Integration of Endothelial Cell-Covered Hepatocytes Spheroids for Construction of Vascularized Liver Tissue, Animal Cell Technology: Basic & Applied Aspects,Proceedings of the 21st Annual and International Meeting of the Japanese Association for Animal Cell Technology, Vol.16,pp.45-50, 2010.05.
100. M. INAMORI, H. MIZUMOTO, T. KAJIWARA, Investigation of medium perfusion through scaffold-free tissue constructs using endothelial cell-covered spheroids in vitro, Biochemical Engineering Journal, Vol.50, No.3, pp.116-121, 2010.05.
101. Seiji Shiromoto, Yasushi Masutani, Masaaki Tsutsubuchi, Yoshiaki Togawa, Toshihisa Kajiwara, The effect of viscoelasticity on the extrusion drawing in film-casting process, Rheologica Acta, 10.1007/s00397-010-0454-9, 49, 7, 757-767, 2010.04, [URL], The governing rheological property for extrusion drawing in film-casting process is proposed in this study. The experiment of film-casting process using the high-pressure process low-density polyethylene (LDPE) was performed. The non-isothermal viscoelastic simulation of the film casting experiment was also carried out to explain the experimental results. Film width reduction phenomenon in an air gap, so-called neck-in behavior, was investigated by using the simulation of the LDPE and the model fluids exhibiting specific viscoelasticity. The neck-in phenomenon was also examined using theoretical model based on force balance and deformation type of a film. As a result, the neck-in normalized by the air gap was in good correlation with the ratio of planar to uniaxial elongational viscosity rather than the strain hardening nature of uniaxial elongational viscosity..
102. H.Yoshida, S.Fujino and T.Kajiwara, Afterglow luminance property of phosphorescent phosphor  SrAl2O4:Eu2+,Dy3+- Glass Composites, Journal of Ceramic Society of Japan, Vol.118,No.1381,pp784-787., 2010.02.
103. H.Yoshida, H.Abe, T. Taguri, F.Ohashi,S.Fujino and T. Kajiwara, Antimicrobial effect of porcelain glaze with silver-clay antimicrobial agent, Journal of Ceramic Society of Japan, Vol.118,No.1379,pp571-574.

, 2010.02.
104. Seiji INABA and Shigeru FUJINO, Empirical Equation for Calculating the Density of Oxide Glasses, Journal of American Ceramic Society, Vol.93, pp.217-220, 2010.01.
105. S. Shiromoto, Y. Masutani, M. Tsutsubuchi, Y. Togawa, T. Kajiwara , A Neck-in Model in Extrusion Lamination Process, Polymer Engineering and Science, Vol. 50, Issue 1, pp.22-31, 2010.01.
106. Seiji Shiromoto, Yasushi Masutani, Masaaki Tsutsubuchi, Yoshiaki Togawa, Toshihisa Kajiwara, A neck-in model in extrusion lamination process, Polymer Engineering and Science, 10.1002/pen.21502, 50, 1, 22-31, 2010.01, [URL], In this study, the experiment of the extrusion lamination process using high-pressure process low-density polyethylene (LDPE) was performed. The nonisothermal viscoelastic simulation of the extrusion lamination experiment was also carried out. The simulation results were in good agreement with the experimental data within wide range of take up velocity and air gap length. We developed the theoretical model based on force balance and deformation type of a film to predict the neck-in behavior in the extrusion lamination or cast film process. It was suggested from the neck-in model that the neck-in correlates with the ratio of planar to uniaxial elongational viscosity. It was confirmed that the neck-in model could predict the film edge shape and neck-in properly for conventional LDPE..
107. Hideki Yoshida, Shigeru Fujino, Toshihisa Kajiwara, Afterglow luminance property of phosphorescent phosphor SrAl
2
O
4
:Eu
2+
, Dy
3+
-glass composites, Journal of the Ceramic Society of Japan, 10.2109/jcersj2.118.784, 118, 1381, 784-787, 2010.01, [URL], The effect of mixing ratio, firing temperature and matrix glass composition on afterglow luminance property of SrAl
2
O
4
: Eu
2+
,Dy
3+
-glass composites were investigated. As a result, the brightness showed a maximum at 35mass% of the mixing ratio of the phosphor for the glass and 780°C of the firing temperature. And it was increased with decreasing the Na
2
O content of the matrix glass. From the backscattered electron and the EDX analysis, it is thought that the intermediate layers generated between the phosphors and the Na
2
O-poor matrix glass work as antireflective and the phosphor particles in the composite emit phosphorescent light more efficiently. As higher the basicity parameter, B, the intermediate layer was clearer, which means that the reactivity at the phosphor/glass boundaries was lower, and the narrow reaction layers was formed..
108. Hiroyuki Ijima, Hiroshi Mizumoto, Kohji Nakazawa, Toshihisa Kajiwara, Taku Matsushita, Kazumori Funatsu, Hepatocyte growth factor and epidermal growth factor promote spheroid formation in polyurethane foam/hepatocyte culture and improve expression and maintenance of albumin production, Biochemical Engineering Journal, 10.1016/j.bej.2009.06.012, 47, 1-3, 19-26, 2009.12, [URL], In our previous pre-clinical study with pig hepatic failure, an artificial liver with polyurethane foam (PUF)/primary porcine hepatocyte spheroids had superior curative effect. We examined the effect of hepatocyte growth factor (HGF), also known as scatter factor, on the quick formation of hepatocyte spheroids and albumin production. Spheroids were formed in the pores of PUF within 3 days regardless of addition of growth factors. In particular, spheroids were formed within 1 day in medium containing 100 ng/ml HGF and 50 ng/ml epidermal growth factor (EGF). 10,000 ng/ml HGF was effective for albumin production, but the activity dramatically decreased after 6 days in EGF-free medium. On the other hand, 100 ng/ml HGF was effective for albumin production in EGF-containing medium. Albumin production rate with ≥1000 ng/ml HGF was about 1.5 times higher than that with 100 ng/ml HGF. Furthermore, albumin production rate at 3 weeks was about 1.5 times higher than that at 2 days with 1000 ng/ml HGF. The maintenance of albumin production rate depended on the activity of the individual cell and not cell growth. In other words, we were able to show the effectiveness of HGF for functional hepatocyte organoid formation in PUF pores. Crown.
109. Hiroshi Ikeda, Shigeru Fujino, Toshihisa Kajiwara, Preparation and characterization of BaO-TeO2 thin films obtained from tellurium(VI) alkoxide by a sol-gel method, Journal of the American Ceramic Society, 10.1111/j.1551-2916.2009.03280.x, 92, 11, 2619-2622, 2009.11, [URL], BaO-TeO2 thin films were prepared from tellurium(VI) alkoxide by a sol-gel method and their structure was investigated by X-ray diffractometry, Fourier transform infrared spectrometry, and 125Te static nuclear magnetic resonance. Their crystallization temperature (Tc), optical transmittance, and dielectric constant were measured, and their refractive index was calculated from the transmission spectra. The results indicate that the BaO-TeO2 thin films were composed of TeO6 and TeO 4 units, and had a Tc of ∼520°C, refractive index of ∼1.79, dielectric constant of ∼20. These films had a Tc higher than the glass prepared by a melt-quench method, but their refractive index and dielectric constant were lower. These differences may be due to differences in their structural units..
110. Jun ichi Takimoto, Toshihisa Kajiwara, A special issue for computational rheology, Nihon Reoroji Gakkaishi, 10.1678/rheology.37.57, 37, 2, 2009.09, [URL].
111. Takeshi Inomoto, Toshihisa Kajiwara, Three-dimensional viscoelastic analysis of multi-layer polymer flow by numerical simulation, Nihon Reoroji Gakkaishi, 10.1678/rheology.37.91, 37, 2, 91-96, 2009.09, [URL], We performed three-dimensional viscoelastic analysis of multi-layer polymer flow by numerical simulation, and investigated the effects of the elongational properties on the encapsulation phenomenon in the coextrusion process. The K-BKZ model with multiple relaxation times was used as viscoelastic constitutive equation, and the PSM type damping function was used for this model. This model is convenient to investigate the effects of the elongational properties, because the parameter b in this model can control only the elongational properties. Also we can extract the effects only of the elongational properties, because the second normal stress difference in this model is zero. In this study, we assumed that multi-layer polymer flow of Fluid I (less viscous) and Fluid II (more viscous) flows in three kinds of channels with different taper angle (parallel, tapered contraction and tapered expansion). As a result, by increasing the b ratio between Fluid I and Fluid II (βIII) from 0.1 to 10.0, the degree of encapsulation (DE) hardly changed at confluence, increased at contraction part and decreased at expansion part. These results mean that the elongational properties clearly influence the encapsulation phenomenon especially at contraction part and expansion part..
112. M. Inamori, H. Mizumoto, T. Kajiwara, An Approach for Formation of Vascularized Liver Tissue by Endothelial Cell–Covered Hepatocyte Spheroid Integration, 2037 Tissue Engineering Part A, Vol.15,pp.2029-2037, 2009.08.
113. Masakazu Inamori, Hiroshi Mizumoto, Toshihisa Kajiwara, An approach for formation of vascularized liver tissue by endothelial cell-covered hepatocyte spheroid integration, Tissue Engineering - Part A, 10.1089/ten.tea.2008.0403, 15, 8, 2029-2037, 2009.08, [URL], Tissue vascularization in vitro is necessary for cell transplantation and is a major challenge in tissue engineering. To construct large and regularly vascularized tissue, we focused on the integration of endothelial cell-covered spheroids. Primary rat hepatocytes were cultured on a rotary shaker, and 100-150μm spheroids were obtained by filtration. The hepatocyte spheroids were coated with collagen by conjugation with a type 1 collagen solution. Collagen-coated hepatocyte spheroids were cocultured with human umbilical vein endothelial cells (HUVECs), and monolayered HUVEC-covered hepatocyte spheroids were constructed. Without a collagen coat, many HUVECs invaded hepatocyte spheroids but did not cover the spheroid surface. To construct regularly vascularized tissue, we packed HUVEC-covered hepatocyte spheroids in hollow fibers used for plasma separation. Packed spheroids attached to each other forming a large cellular tissue with regular distribution of HUVECs. At day 9 after packing, HUVECs invaded the hepatocyte spheroids and a dense vascular network was constructed. Collagen coating of spheroids is useful for the formation of endothelial cell-covered spheroids and subsequent regular vascularized tissue construction..
114. T. Inomoto,T. Kajiwara, Three-dimensional Viscoelastic Analysis of Multi-Layer Polymer Flow by Numerical Simulation, Nihon Reoroji Gakkaishi, Vol.37,pp.91-96, 2009.06.
115. T. Kusumi, K. Ishihara, H. Mizumoto, K. Nakazawa, H. Ijima, K. Funatsu, T. Kajiwara, Evaluation of A Bioreactor with Stacked Sheet Shaped Organoids of Primary Hepatocytes, Journal of Bioscience and Bioengineering, Vol.107,pp.552-555, 2009.05.
116. 松尾雄二,名嘉山祥也,梶原稔尚, 高分子溶融体のダイ内多層流動の粘弾性解析, 日本機械学会論文集(B編), Vol.75,pp.929-936, 2009.05.
117. Tomoaki Kusumi, Kazuhisa Ishihara, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, Evaluation of a bioreactor with stacked sheet shaped organoids of primary hepatocytes, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2009.01.005, 107, 5, 552-555, 2009.05, [URL], Hepatocyte organoids have an in vivo-like cell morphology and maintain cell viability and function in vitro. On the other hand, the oxygen supply to hepatocytes is sometimes limited in the core of organoids that are more than 100 μm in thickness. In this study, we designed and examined a new bioreactor using sheet-shaped organoids (organoid-sheets) in which the thickness was controlled to prevent hepatocyte death in the core of organoid due to limitation of oxygen supply. The cell culture space consisted of stacked organoid formation spaces and medium flow channels. Each space was separated by flat porous polycarbonate membranes, and the organoid thickness was controlled at 100 μm with a stainless steel spacer. Freshly isolated hepatocytes (7.0 × 107) were immobilized in the bioreactor, yielding a cell density of 4.5 × 107 cells/cm3-bioreactor. Of the five flow rates tested (1.0, 5.0, 10, 20, and 50 mL/min), the bioreactor with the 10 mL/min had the highest ammonia removal and albumin secretion activities for at least 14 days. In conclusion, a new bioreactor controlling organoid thickness is useful for achieving high cell density culture and the maintenance of hepatocyte function to avoid cell death in the core of the organoids due to limitation of oxygen supply. The bioreactor may be useful for the development of various applications using cultured hepatocytes..
118. Yuji Matsuo, Yasuya Nakayama, Toshihisa Kajiwara, Viscoelastic analysis of multilayer polymer melt flow in die, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.75.753_929, 75, 753, 929-936, 2009.05, [URL], In multi-layer coextrusion of polymer melts, various kinds of interfacial instabilities occur due to processing conditions, die geometry, and the rheological properties of each layer. Suppressing the interfacial instabilities is a crucial task in manufacturing a multi-layer polymer film of high functionality. However, multi-layer flow of viscoelastic fluids has been poorly understood. We performed a course of viscoelastic simulations of multi-layer flow to clarify the flow and stress states, and investigated the effect of channel geometry and the layer arrangement of viscoelastic fluids with different rheological properties on it. It was found that by arranging the fluid with higher viscosity at the outermost layer, large strain rate developed in the second layer of a fluid with lower viscosity. Furthermore, change of thickness of layers caused by die channel enhanced the jump of the normal stress difference at interfaces. This behavior was most enhanced in the arrangement of the high-viscosity fluids at the outer-most layer. It is supposed that this elasticity inhomogeneity might be an important factor controlling the interfacial instabilities in viscoelastic multi-layer co-extrusion..
119. H. Mizumoto, K. Ishihara, K. Nakazawa, H. Ijima, K. Funatsu, T. Kajiwara, A New Culture Technique for Hepatocyte Organoid Formation and Long-Term Maintenance of Liver Specific Functions, Tissue Engineering Part C: Methods, Vol.14,pp.167-175, 2008.06.
120. Y. Irie, H. Mizumoto, S. Fujino, T. Kajiwara, Reconstruction of Cartilage Tissue Using Scaffold-Free Organoid Culture Technique, Journal of Bioscience and Bioengineering, Vol.105,pp.450-453, 2008.05.
121. Yutaka Irie, Hiroshi Mizumoto, Shigeru Fujino, Toshihisa Kajiwara, Reconstruction of cartilage tissue using scaffold-free organoid culture technique, Journal of Bioscience and Bioengineering, 10.1263/jbb.105.450, 105, 5, 450-453, 2008.05, [URL], We applied the scaffold-free culture method to chondrocytes and attempted to reconstitute articular cartilage grafts. Primary rat costal chondrocytes were immobilized into hollow fibers by centrifugation at a density of 3×108 cells/cm3 to induce the formation of cylindrical-shaped multicellular aggregates (organoids) and cultured for one month. The organoids were evaluated by histological and gene expression analyses. Chondrocytes formed cylindrical organoids in hollow fibers (HFs). Histochemical analysis revealed the accumulation of a cartilage extracellular matrix (collagen and proteoglycan) around cells in the lumen of HFs with culture time, forming a low-cellular-density tissue similar to native cartilage by day 28. Furthermore, in contrast to that in traditional monolayer culture, the organoid maintained the gene expression of the cartilage extracellular matrix (type II collagen, aggrecan) for one month of culture. In conclusion, our organoid formation method was effective in producing a cartilage-like tissue. This result suggests that the technique may be applicable to the development of an articular cartilage graft..
122. K. Matsumoto, H. Mizumoto, K. Nakazawa, H. Ijima, K. Funatsu, T. Kajiwara, Hepatic Differentiation of Mouse Embryonic Stem Cells in a Three-Dimensional Culture System Using Polyurethane Foam, Journal of Bioscience and Bioengineering, Vol.105,pp.350-354, 2008.04.
123. Kinya Matsumoto, Hiroshi Mizumoto, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, Hepatic differentiation of mouse embryonic stem cells in a three-dimensional culture system using polyurethane foam, Journal of Bioscience and Bioengineering, 10.1263/jbb.105.350, 105, 4, 350-354, 2008.04, [URL], Embryonic stem (ES) cells are a type of pluripotent stem cell line isolated from the inner cell mass of blastocysts and characterized by an almost unlimited self-renewal capacity and differentiation potential in vitro into multiple cell lineages. Therefore the use of ES cells has recently received much attention as a novel cell source for various hybrid artificial organs. To use ES cells, it is necessary to be able to produce functional matured cells from ES cells in large quantities. In this study, we applied polyurethane foam (PUF)/spheroid culture, which enables spontaneous spheroid formation and mass cultivation of cultured cells, to mouse ES cells for hepatic differentiation. Mouse ES cells spontaneously formed spherical multicellular aggregates (spheroids) in the pores of the PUF within 1 d. To induce hepatic differentiation, specific growth factors were added to the culture medium. Mouse ES cells proliferated by day 20, and high cell density (about 1.0×108 cells/cm3-PUF) was achieved. Differentiating ES cells expressed endodermal-specific genes, such as α-fetoprotein, albumin and tryptophan 2,3-dioxygenase. The activity of ammonia removal of mouse ES cells per unit volume of the module was detected by day 21 and increased with culture time. Maximum expression levels were comparable to those of primary mouse hepatocytes. Mouse ES cells could express liver-specific functions at high level because of the high cell density culture and hepatic differentiation. These results suggest that the PUF/spheroid culture method could be useful to develop mass differentiation cultures..
124. Y. Irie, H. Mizumoto, S. Fujino, T. Kajiwara, Development of Articular Cartilage Grafts Using Organoid Formation Techniques, Transplantation Proceedings, vol.40, pp631-633, 2008.03.
125. K. Matsumoto, H. Mizumoto, K. Nakazaawa, H. Ijima, K. Funatsu, T. Kajiwara, Hepatic Differentiation of Mouse Embryonic Stem Cells in a Bioreactor Using Polyurethane/Spheroid Culture, Transplantation Proceedings, vol.40, pp614-616, 2008.03.
126. H. Mizumoto, K. Aoki, K. Nakazawa, H. Ijima, K. Funatsu, T. Kajiwara, Hepatic Differentiation of Embryonic Stem Cells in HF/Organoid Culture, Transplantation Proceedings, vol.40, pp611-613, 2008.03.
127. 藤野茂,國川晃太郎,梶原稔尚, 粉末焼結法による高純度透明シリカガラスの作製と真空紫外透過特性, 粉体および粉末治金, vol.55, pp216-220, 2008.03.
128. Y. Irie, H. Mizumoto, S. Fujino, T. Kajiwara, Development of Articular Cartilage Grafts Using Organoid Formation Techniques, Transplantation Proceedings, 10.1016/j.transproceed.2008.01.024, 40, 2, 631-633, 2008.03, [URL], In order to develop articular cartilage grafts, one must control shape and safety. We have developed scaffold-free culture methods in which the cells form multicellular aggregates (organoids). In this study, we applied the organoid culture method to chondrocytes attempting to reconstitute articular cartilage grafts. Primary rat costal chondrocytes and subcultured human articular chondrocytes were immobilized in hollow fibers by centrifugation at a density of 3 × 108 cells/cm3 to induce the formation of cylindrical-shaped organoids. To improve convenience, we developed a culture device to form sheet-shaped organoids (organoid-sheet). Primary bovine articular chondrocytes were cultured in this device. These organoids were evaluated by histological and gene expression analyses. In the primary rat culture system, chondrocytes formed cylindrical organoids in hollow fibers. Histochemical analysis revealed the presence of extracellular matrix (collagen and proteoglycan). The organoid maintained cartilage-specific gene expression (type II collagen, aggrecan) for 1 month of culture. In the subcultured human chondrocyte system, the organoid regained the decreased cartilage-specific gene expression. In the primary bovine culture system, the cells formed a 300 μm thickness organoid-sheet including abundant extracellular matrix. In conclusion, our organoid formation method was effective to form cartilage-like tissue. This result suggested that the technique may be applicable for the development of an articular cartilage graft..
129. Shigeru Fujino, Koutaro Kunikawa, Toshihisa Kajiwara, Fabrication of sintered silica glass and its vacuum ultraviolet transparency, Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, 10.2497/jjspm.55.216, 55, 3, 216-220, 2008.03, [URL], Transparent silica glasses were obtained by sintering a green compact in diverse atmospheres. The green compacts were fabricated by slip-casting methods for high-purity silica glass powder. The relationships between sintering atmosphere and sintering temperature that result in transparent, sintered silica glass were shown. It was found that the transparency-forming region of sintered silica glass corresponds to a sintering temperature above 1400°C and high-vacuum (10-4 Pa) atmosphere conditions. We investigate the fabrication of transparent and hydroxyl-free silica glass by a powder-sintered method. The sintered silica glass with 10 ppm OH content exhibited the highest transmittance at 157 nm (76% for 2 mm sample thickness). Refractive index dispersion curves in the wavelength region of 0.194 μm to 3.584 μm are presented for the sintered silica glass by minimum deviation method..
130. K. Matsumoto, Hiroshi Mizumoto, K. Nakazawa, Hiroyuki Ijima, K. Funatsu, Toshihisa Kajiwara, Hepatic Differentiation of Mouse Embryonic Stem Cells in a Bioreactor Using Polyurethane/Spheroid Culture, Transplantation Proceedings, 10.1016/j.transproceed.2008.01.025, 40, 2, 614-616, 2008.03, [URL], Background: We have previously developed a hybrid artificial liver (HAL) using polyurethane foam (PUF)/hepatocyte spheroid culture. The PUF-HAL has been successfully scaled up to a clinical level. However, one of the most difficult problems for clinical application of HALs is obtaining a cell source. We now focused our attention on embryonic stem (ES) cells as a potential source for HAL. In this study, we investigated the differentiation of mouse ES (mES) cells into functional hepatocytes in the PUF-HAL module. Methods: The PUF-HAL module included a cylindrical PUF block having many capillaries for medium flow. mES cells were immobilized in the module. To induce hepatic differentiation, growth factors were added to the culture medium. We evaluated cell density, gene expression analysis, and liver-specific functions. Results: mES cells spontaneously formed spherical multicellular aggregates (spheroids) in the pores of PUF. mES cells proliferated by 20 days, achieving a high cell density (about 1 × 108 cells/cm3 PUF). Differentiating ES cells expressed endodermal-specific genes such as α-fetoprotein, albumin, and tryptophan 2, 3-deoxygenase. The activity of ammonia removal of mES cells per unit volume of the module was detectable by 15 days and increased with culture time. Maximal expression levels were comparable to those of primary (porcine and human) hepatocytes. Summary: mES cells immobilized in the PUF module expressed liver-specific functions at high level, because of high cell density in culture and hepatic differentiation. These results indicated that PUF module-immobilized mES cells may be useful as a biocomponent of HALs..
131. Hiroshi Mizumoto, K. Aoki, K. Nakazawa, Hiroyuki Ijima, K. Funatsu, Toshihisa Kajiwara, Hepatic Differentiation of Embryonic Stem Cells in HF/Organoid Culture, Transplantation Proceedings, 10.1016/j.transproceed.2008.01.023, 40, 2, 611-613, 2008.03, [URL], Objective: The use of embryonic stem cells (ES cells) has recently received much attention as a novel cell source for various hybrid artificial organs. To use ES cells, it is necessary to be able to produce functional mature cells from ES cells in large quantities. We applied HF/organoid culture, where cultured cells formed cylindrical multicellular aggregates (organoids) in the lumen of hollow fibers, to mouse and cynomolgus monkey ES cells for hepatic differentiation. Materials and Methods: ES cells were injected into hollow fibers. The hollow fibers were centrifuged to induce organoid formation and cultured in medium including factors for hepatic differentiation. To determine the characteristics of cells in the bundle, we evaluated gene expression and liver-specific functions. Results: ES cells immobilized inside hollow fibers proliferated and formed cylindrical organoids. In mouse ES cell cultures, the expression of mRNAs of hepatocyte-specific genes increased with culture time. Ammonia removal activity detected at 15 days increased with culture time. Albumin secretion activity detected at 12 days increased by 21 days. In cynomolgus monkey ES cell cultures, ES cells showed spontaneous ammonia removal functions. The maximum levels of these functions per unit volume of the hollow fibers were roughly comparable to those of primary hepatocyte-organoids. Conclusions: ES cells differentiated into hepatocyte-like cells using the organoid culture technique. The results indicated that the combination of ES cells and an organoid culture technique was useful to obtain mature hepatocytes..
132. K. Aoki, H. Mizumoto, K. Nakazawa, K. Funatsu, T. Kajiwara, Evaluation of a hybrid artificial liver module with liver lobule-like structure in rats with liver failure, The International Journal of Artificial Organs, vol.31, pp55-61, 2008.02.
133. Hiroshi Mizumoto, Kazuhisa Ishihara, Kohji Nakazawa, Hiroyuki Ijima, Kazumori Funatsu, Toshihisa Kajiwara, A new culture technique for hepatocyte organoid formation and long-term maintenance of liver-specific functions, Tissue Engineering - Part C: Methods, 10.1089/ten.tec.2007.0373, 14, 2, 167-175, 2008.01, [URL], To develop a useful hybrid artificial liver, it is important to use cultured hepatocytes that maintain liver-specific functions for a long time. These requirements were achieved recently by the use of a hepatocyte multicellular aggregate (organoid) with a tissue-like structure. In this study, we developed a three-dimensional culture of hepatocytes that formed an organoid. Primary rat hepatocytes were immobilized inside hollow fibers (for plasma separation) by centrifugation. Hepatocytes formed a cylindrical organoid (cylindroid) of 200 μm in diameter by day 2 of culture. We used two types of culture media, medium A (Williams' medium E containing insulin and epidermal growth factor) and medium B (Dulbecco's modified Eagle's medium containing insulin, epidermal growth factor, and hydrocortisone). In medium A, the hepatocyte cylindroid diminished after 14 days of culture and liver-specific functions of the hepatocyte cylindroid nearly disappeared after 1 month of culture. In contrast, hepatocyte cylindroid cultured in medium B maintained its morphology and liver-specific functions for 2-5 months. These results indicate that a combination of the new culture technique and suitable culture medium is effective for expression and maintenance of liver-specific functions of hepatocytes. This culture technique will be helpful in the development of a hybrid artificial liver..
134. K. Aoki, Hiroshi Mizumoto, K. Nakazawa, K. Funatsu, Toshihisa Kajiwara, Evaluation of a hybrid artificial liver module with liver lobule-like structure in rats with liver failure, International Journal of Artificial Organs, 10.1177/039139880803100108, 31, 1, 55-61, 2008.01, [URL], We studied the recovery of rats with fulminant hepatic failure (FHF) by treating them with our original hybrid artificial liver support system (HALSS). We developed an original artificial liver module having a liver lobule-like structure (LLS). This module consists of many hollow fibers regularly arranged in close proximity and hepatocyte aggregates (organoids) induced into the extra capillary space of the module by centrifugal force. The LLS module can express some liver specific functions at high levels and maintain them for several months in vitro. In this study, we evaluated the efficacy of our LLS-HALSS by using rats with FHF induced by a method that combined partial hepatectomy with hepatic ischemia. In the animal experiments, blood ammonia levels rapidly increased in the control group (sham-HALSS group). These rats died during or immediately after application of the sham-HALLS. On the other hand, in the LLS module application group (LLS-control group), the increase in blood ammonia was completely suppressed and all rats recovered. Blood constituents at 4 weeks after application were at normal levels, and the weight of the liver was the same as that of a normal rat. These results indicate that HALSS may be useful for treating liver failure patients until liver transplantation can be performed or until regeneration of the native liver occurs..
135. T. Ishikawa, F. Nagano, Toshihisa Kajiwara, Stress induced mixing in rotor elements of a counter-rotating pi continuous mixier, Society of Plastics Engineers Annual Technical Conference: Plastics Encounter at ANTEC 2007
Society of Plastics Engineers Annual Technical Conference
Plastics Encounter at ANTEC 2007, Conference Proceedings
, 485-489, 2007.09, The numerical approaches we originally developed were applied to the rotor element of a counter-rotating continuous mixer in order to evaluate the mixing performance. Our approaches include the combination of the 3-D FEM based flow analysis and the marker-particle tracking method. The kneading block of a co-rotating twin screw extruder was also investigated in order to contrast the mixing behavior with the rotor. The numerical results showed that the stress induced mixing in rotor elements totally depends upon the process conditions and high rotational speed achieved the uniform mixing. The uniform mixing was expected when the polymer melt underwent narrow stress distribution in the flow channel. The numerical approaches are the effective method to design the process conditions in order to improve the stress induced mixing..
136. Y. Nakayama, M. Tanidono, H. Tomiyama, T. Kajiwara, Simulation Study on Mixing Process in Twin-Screw Extruders, Proceedings of 23rd Annual Meeting of the Polymer Processing Society, 2007.06.
137. K. Aoki, K. Noda, H. Mizumoto, K. Nakazawa, K. Funatsu, T. Kajiwara, Development of A Hybrid Artificial Liver Module With Hepatocyte Organoids Induced by Centrifugal Force, Proceedings of 2006 Japan/Taiwan/Korea Chemical Engineering Congerence, pp.19-20, 2006.11.
138. E. Inoue, T. Tsuji, T. Kajiwara, K. Funatsu, Y. Nakayama, Simulation for Mixing Process in the Solid Conveying Zone of a Twin-screw Extruder, Seikei-Kakou,, Vol. 18, pp.826-830, 2006.11.
139. T. Kajiwara, H. Tomiyama, A. Uotani, S. Inoue, K. Funatsu, Finite Element Analysis of Melt Mixing Zone in Twin Screw Extruders with Special Geometries, Seikei-Kakou,, Vol. 18, pp.819-825, 2006.11.
140. T. Ishikawa, F. Nagano, T. Kajiwara, K. Funatsu, Tip-clearance Effect on Mixing Performance of Twin Screw Extruders, International Polymer Processing, Vol. 12, pp.354-360, 2006.09.
141. T. Ishikawa, F. Nagano, T. Kajiwara, Stress Induced Mixing of Rotor Elements in Counter-Rotating Continuous Mixers, Proceedings of 22nd Annual Meeting of the Polymer Processing Society, 2006.07.
142. Toshihisa Kajiwara, Masato Yamamura, Tomoko Asahina, Relationship between neck-in phenomena and rheological properties in film casting, Nihon Reoroji Gakkaishi, 10.1678/rheology.34.97, 34, 2, 97-103, 2006.07, [URL], We numerically demonstrate that the ratio of uniaxial to planar elongational viscosity controls the neck-in phenomena of the casting polymer films, i.e., the decrease in film width value for both viscous and viscoelastic fluids. Quasi-three-dimensional numerical simulations of an isothermal film casting process were performed using a finite element method for two viscoelastic fluids using Larson and PTT models, purely-viscous non-Newtonian fluids using Cross model and Newtonian fluids. The increase in take-up velocity relative to that in extrusion showed particular film deformations of neck-in depending upon the rheological properties in the models. The results indicate that the film width is determined by the ratio of uniaxial to planar elongational viscosity rather than the extension-thickening nature in uniaxial elongation. The computations using different fluid models show that the viscosity ratio is universal for predicting the neck-in value of the stretching polymer films not only in viscoelastic but also in pure viscous fluids..
143. J. Fukuda, K. Okamura, K. Ishihara, H. Mizumoto, K. Nakazawa, H. Ijima, T. Kajiwara, K. Funatsu, Differentiation Effects by the Combination of Spheroid Formation and Sodium Butyrate Treatment in Human Hepatoblastoma Cell Line (Hep G2): A Possible Cell Source for Hybrid Artificial Liver, Cell Transplantation, Vol.14, No. 10, pp.819-827, 2006.03.
144. K. Ishihara, H. Mizumoto, K. Nakazawa, T. Kajiwara, K. Funatsu, Formation of a sheet-shaped organoid using rat primary hepatocytes for long-term maintenance of liver-specific functions, The International Journal of Artificial Organs, Vol.29, No.3, 318-328, 2006.03.
145. K. Ishihara, H. Mizumoto, K. Nakazawa, Toshihisa Kajiwara, K. Funatsu, Formation of a sheet-shaped organoid using rat primary hepatocytes for long-term maintenance of liver-specific functions, International Journal of Artificial Organs, 10.1177/039139880602900310, 29, 3, 318-328, 2006.03, [URL], In recent years, use of hepatocyte aggregates has led to development of a hybrid artificial liver support system (HALSS) that has high performance. However, in general, their thickness is 100 μm or more, and generation of a dead cell layer due to oxygen exhaustion inside the aggregates has been a universal problem. The present study proposes a novel organoid culture method with better performance than previous organoid culture methods by forming a sheet-shaped organoid (organoid-sheet) with a thickness of approximately 100 μm. The cell number of the organoid-sheet was maintained at approximately 75% of the initial number at 4 days of culture. On the other hand, that of a cylindrical organoid (cylindroid), which formed inside of a plasma separation hollow fiber with 285 μm inner diameter in our previous study, decreased to approximately 50% within 2 days. The ammonia removal rate of the cells in the organoid-sheet was higher than that of the cells in the cylindroid on the first day, but it decreased during the culture time. At day 15, the rate was reduced by almost 50% with respect to the value on the first day. The cells in the cylindroid displayed a lower ammonia removal rate. A significant difference was not observed between the albumin synthesis rates of the two cultures on the first day. However, over a period of time the cells in the organoid-sheet showed a higher albumin synthesis rate than cells in the cylindroid. As this novel organoid maintains these functions for at least 1 month, it is expected to be applied for the development of a HALSS with higher performance..
146. T. Kajiwara, M. Yamamura, T. Asahina, Relationship between Neck-in Phenomena and Rheological Properties in Film Casting, Nihon Reoroji gakkaishi, Vol.34, No.2, 97-103, 2006.02.
147. T. Ishikawa, F. Nagano, Toshihisa Kajiwara, K. Funatsu, Tip-clearance effect on mixing performance of twin screw extruders, International Polymer Processing, 10.3139/217.0088, 21, 4, 354-360, 2006.01, [URL], In order to evaluate the tip-clearance effect on mixing, 3-D numerical simulations were applied to kneading block section of co-rotating twin screw extruders. The software we used was originally developed for non-Newtonian and non-isothermal flow analysis based on the finite element technique. The marker-particle tracking analysis was also developed in order to estimate the particle path, residence time distribution, stress and strain history, and so on. The stress distribution obtained by the above-mentioned simulations suggested the following mixing mechanisms. The kneading block with the small tip-clearance (TC) caused the bimodal stress distribution which had peaks in both high and low stress level. The marker-particles which overpassed the TC formed the peak at the high stress level and the other particles contributed to the peak at the low stress level. In other words, a large number of particles evaded the TC and it caused heterogeneous stress induced mixing. On the other hand, the large tip-clearance caused the narrow and sharp stress distribution because most of the particles passed over the TC. The stress level was not high, however, homogeneous stress induced mixing was expected. Since the tip-clearance applied a significant effect to the dispersive mixing, it should be optimised in accordance with the material design..
148. J. Fukuda, K. Okamura, K. Ishihara, H. Mizumoto, K. Nakazawa, H. Ijima, T. Kajiwara, Kanimori Funatsu, Differentiation effects by the combination of spheroid formation and sodium butyrate treatment in human hepatoblastoma cell line (Hep G2)
A possible cell source for hybrid artificial liver, Cell Transplantation, 10.3727/000000005783982503, 14, 10, 819-827, 2005.12, [URL], The aim of this study was to investigate the feasibility of human hepatoblastoma cell line (Hep G2), which differentiates by spheroid formation, and treatment with sodium butyrate (SB) as a cell source for hybrid artificial liver (HAL). Hep G2 spontaneously formed spheroids in polyurethane foam (PUF) within 3 days of culture and restored weak ammonia removal activity. Treatment with SB, which is a histone deacetylase inhibitor, further increased the ammonia removal activity of Hep G2 spheroids in a concentration-dependent manner. The activation of ornithine transcarbamylase-a urea cycle enzyme-was significantly related to the upregulation of ammonia removal by spheroid formation, but scarcely contributed to the further upregulation following SB treatment. In contrast with ammonia removal, treatment with SB reduced the albumin secretion of Hep G2 spheroids in a concentration-dependent manner. In the PUF-HAL module in a circulation culture, the ammonia removal rate and albumin secretion rate (per unit volume of the module) of Hep G2 spheroids treated with 5 mM SB were almost the same as those of primary porcine hepatocyte spheroids. These results suggest that simultaneous use of spheroid formation and SB treatment in Hep G2 is beneficial in enhancing the functions of human hepatocytes with potential applications in regenerative medicine and drug screening..
149. T. Kajiwara, A. Uotani, H. Tomiyama, K. Funatsu, Finite Element Analysis of Melt Mixing Zone in Twin Screw Extruders with Special Geometries, Proceedings of Asian Workshop on Polymer Processing 2005, CD-ROM, 2005.10.
150. S. Kagemoto, T. Kajiwara, K. Funatsu, Development of Prediction Technique of Materials Behavior in Twin Screw Extruders Using the Particles Simulation Method, Proceedings of Asian Workshop on Polymer Processing 2005, CD-ROM, 2005.10.
151. T. Kajiwara, A. Uotani, H. Tomiyama, K. Funatsu, Finite Element Analysis of Melt Mixing Zone in Twin Screw Extruders with Special Geometries, Proceedings of 21th Annual Meeting of the Polymer Processing Society, CD-ROM, 2005.06.
152. T. Ishikawa, F. Nagano, T. Kajiwara, K. Funatsu, Tip-clearance Effect on Mixing Performance of Twin Screw Extruders, Proceedings of 21th Annual Meeting of the Polymer Processing Society, CD-ROM, 2005.06.
153. J. Fukuda, H. Mizumoto, K. Nakazawa, T. Kajiwara, K. Funatsu, Hepatocyte organoid culture in elliptic hollow fibers to develop a hybrid artificial liver, The International Journal of Artificial Organs, 27, 12, 1091-1099, Vol.27, No.12, pp.1091-1099, 2004.12.
154. J. Fukuda, H. Mizumoto, K. Nakazawa, T. Kajiwara, Kazumori Funatsu, Hepatocyte organoid culture in elliptic hollow fibers to develop a hybrid artificial liver, International Journal of Artificial Organs, 10.1177/039139880402701213, 27, 12, 1091-1099, 2004.12, [URL], A novel organoid culture was developed in which hepatocytes maintain high liver functions for more than several weeks in vitro. The main disadvantage of tissue-engineered organoids is the lack of a blood vessel structure between the aggregated cells. Because of depletion of oxygen, the thickness from the surface of an organoid at which hepatocytes can survive is limited. This study showed that a rat hepatocyte organoid that forms by using centrifugal force in a hollow fiber (HF) had a survival limit thickness of about 80 - 100 μm from the surface of the organoid. Based on the value, we designed an elliptic HF having less than 150 μm minor diameter by using a simple annealing method. All hepatocytes were supplied with oxygen and formed an organoid without a dead cell layer in this HF. A hepatocyte organoid in an elliptic HF maintained ammonia removal activity twice as high as in the original HF for at least one month during culture. Albumin secretion activity of an organoid in an elliptic HF was also maintained for at least one month and was the same level as that of liver in a living body. In conclusion, organoid culture by using an elliptic HF seems to be a promising technique to develop a hybrid artificial liver..
155. H. Mizumoto, T. Yamaguchi, K. Aoki, K. Nakazawa, T. Kajiwara, K. Funatsu, Development of a hybrid artificial liver module having liver lobule-like strucuture, The 10th Asian Pacific Confederation of Chemical Engineering Congress, pp.1-7, 2004.10.
156. K. Ishihara, J. Fukuda, H. Mizumoto, K. Nakazawa, T. Kajiwara, K. Funatsu, Organoid-sheet formation for hepatocyte and myocardial cell culture, The 10th Asian Pacific Confederation of Chemical Engineering Congress, pp.1-9, 2004.10.
157. T. Kajiwara, K. Nakazawa, J. Fukuda, R. Sakiyama, H. Ijima, Y. Yamashita, M. Shimada, K. Shirabe, E. Tsujita, K. Funatsu, Hybrid artificial liver with polyurethane foam / shperoid culture for treatment of acute liver failure, The 10th Asian Pacific Confederation of Chemical Engineering Congress, pp.1-7, 2004.10.
158. M. Yamamura, T. Kajiwara, H. Kage, Multicomponent diffusion in phase-separating polymer blends with different frictional interactions: a mean-friction model, Chemical Engineering Science, Vol. 58, No. 17, 3891-3899, 2003.09.
159. T. Kajiwara, Y. Terao, A. Uotani, T. Tsuji, H. Tomiyama, K. Funatsu, 3-D Melt Flow Simulation in a Twin Screw Extruder with Grooved Barrel, Proceedings of Europe-Africa regional Meeting of the Polymer Processing Society, CD-ROM, 2003.09.
160. K. Funatsu, T. Tsuji, A. Uotani, T. Kajiwara, Computational Modelling and Simulation of Materials Behavior in a Twin Screw Extruder using Particle Simulation Method, Proceedings of Europe-Africa regional Meeting of the Polymer Processing Society, CD-ROM, 2003.09.
161. Masato Yamamura, Toshihisa Kajiwara, Hiroyuki Kage, Multicomponent diffusion in phase-separating polymer blends with different frictional interactions
A mean-friction model, Chemical Engineering Science, 10.1016/S0009-2509(03)00313-0, 58, 17, 3891-3899, 2003.09, [URL], We present a compact formula for describing the mean frictional forces acting on a molecule in multicomponent systems. The friction-based diffusion theory of Zielinski and Hanley was extended to newly include the friction-average molar velocity as a reference frame. The results showed that the previous diffusion theories are unified by the friction-average concept by properly choosing the average velocity. The present model based on the diffusivity-related molar average velocity provides better predictions for the diffusive flux in a ternary miscible liquid compared to the other existing theories. The application of the model in phase-separating ternary systems revealed that the introduction of a highly diffusive third component into demixing polymer blends promotes a particular enhancement of the spinodal decomposition due to the difference in the frictional interactions between polymers..
162. M. Yamamura, S. Nakamura, T. Kajiwara, H. Kage, K. Adachi, Flow-induce stripe pattern formation in phrase-separating fluids, Polymer, Vol. 44, No. 16, 4699-4704, 2003.07.
163. T. Kajiwara, A. Uotani, T. Tsuji, K. Funatsu, Development of Prediction Technique of Materials Behavior in Twin Screw Extruders Using the Particle Simulation Method, Proceedings of 19th Annual Meeting of the Polymer Processing Society, CD-ROM, 2003.07.
164. Masato Yamamura, Shoko Nakamura, Toshihisa Kajiwara, Hiroyuki Kage, Kitaro Adachi, Flow-induced stripe pattern formation in phase-separating fluids, polymer, 10.1016/S0032-3861(03)00435-X, 44, 16, 4699-4704, 2003.07, [URL], We demonstrated that the introduction of a temperature gradient along the free surface induces a particular stripe pattern in phase-separating fluids. The horizontal temperature gradient drove lateral-periodic spiral liquid motion flowing from warmer to cooler places due to thermocapillarity. Properly chosen polymer compositions and initial film thicknesses in ternary solutions allowed us to promote a phase separation in the presence of spiral flow, which assembled the demixed polymer droplets along the flow-stagnation lines. The resulting assembled phases aligned in the temperature gradient direction and eventually formed periodic polymer stripes involving the same spacing as that of the flow axis. The critical condition for the stripe pattern formation was given by the ratio of two relevant film thicknesses, i.e. the thickness for the onset of the phase separation and that for the cessation of liquid motion..
165. M. Yamamura, K. Nagai, T. Kajiwara, K. Adachi, Stripe pattern breakup in evaporating liquid layer on a plane with horizontal temperature gradient, Chemical Engineering and Processing,, Vol. 42, No. 5, 395-402, 2003.05.
166. Masato Yamamura, Koharu Nagai, Toshihisa Kajiwara, Kitaro Adachi, Stripe pattern breakup in evaporating liquid layer on a plane with horizontal temperature gradient, Chemical Engineering and Processing: Process Intensification, 10.1016/S0255-2701(02)00057-0, 42, 5, 395-402, 2003.05, [URL], We demonstrated that a temperature gradient along the free surface of the evaporating liquid layer induces a transition of liquid motion from the stripe-like longitudinal rolls into ordered convection cells. Experimental observations showed that the breakup of the stripe-like convection occurred at a pair of Marangoni numbers based on the two temperature gradients in the horizontal and vertical directions. We also demonstrated that silica particles accumulated by the convections showed ordered monolayer or randomly-distributed multilayers, which result from the transition of the liquid motion..
167. R. Sakiyama, K. Nakazawa, H. Ijima, H. Mizumoto, T. Kajiwara, M. Ito, H. Ishibashi, K. Funatsu, Recovery of rats with fulminant hepatic failure by using a hybrid artificial liver support system with polyurethane foam/rat hepatocyte spheroids, The International Journal of Artificial Organs, 25, 12, 1144-1152, Vol. 25, No. 12, 1144-1152, 2002.12.
168. R. Sakiyama, K. Nakazawa, H. Ijima, H. Mizumoto, T. Kajiwara, M. Ito, H. Ishibashi, Kazumori Funatsu, Recovery of rats with fulminant hepatic failure by using a hybrid artificial liver support system with polyurethane foam/rat hepatocyte spheroids, International Journal of Artificial Organs, 10.1177/039139880202501205, 25, 12, 1144-1152, 2002.12, [URL], We studied the recovery of rats with fulminant hepatic failure (FHF) by treating then with our original hybrid artificial liver support system (HALSS). FHF was induced by a two-thirds partial hepatectomy and 10 minutes of hepatic ischemia. Rats with FHF were treated with a polyurethane foam/spheroid HALSS including 2.0 × 108 hepatocytes for 1 hour (HALSS group, n = 5), and with the same system without hepatocytes in the artificial liver module as a control experiment (sham-HALSS group, n = 3). The level of blood constituents, ammonia, glucose and creatinine, showed no major difference between the two groups at the end of treatment. All rats in the sham-HALSS group died within 5 hours after treatment. However, the level of blood constituents of rats with FHF in the HALSS group improved with time, and all rats in the HALSS group recovered Liver tissue of rats treated with HALSS showed cell mitosis and improvement from injury. These results indicated that our HALSS has a strong possibility to induce recovery from hepatic failure..
169. M. Yamamura, K. Horiuchi, T. Kajiwara, K. Adachi, Decrease in solvent evaporation rate due to phrase separation in polymer films, AIChE Journal, Vol. 48, No. 11, 2711-2714, 2002.11.
170. Masato Yamamura, Kouhei Horiuchi, Toshihisa Kajiwara, Kitaro Adachi, Decrease in solvent evaporation rate due to phase separation in polymer films, AIChE Journal, 10.1002/aic.690481127, 48, 11, 2711-2714, 2002.11, [URL].
171. M. Yamamura, T. Mikuriya, T. Kajiwara, K. Adachi, Humidity-induced secondary phrase separation in a multizone driner, Industrual and Engineering Chemitry Research, Vol. 41, No. 17, 4409-4413, 2002.08.
172. M. Yamamura, T. Nishio, T. Kajiwara, K. Adachi, Evaporation-induced pattern formation in polymer films via secondary phrase separation, Chemical Engineering Science, Vol. 57, No. 15, 2901-2905, 2002.08.
173. Masato Yamamura, Takatoshi Nishio, Toshihisa Kajiwara, Kitaro Adachi, Evaporation-induced pattern formation in polymer films via secondary phase separation, Chemical Engineering Science, 10.1016/S0009-2509(02)00177-X, 57, 15, 2901-2905, 2002.08, [URL], The ordered necklace-like or cellular pattern formation has been investigated for ternary polymer solutions in which primary and secondary phase separations were induced by the solvent evaporation. The patterns consisted of regular droplet arrays of various diameters, which arose in the pre-existing polymer phases via the secondary phase separation. The pattern formation was enhanced with increasing air velocity and ambient humidity, while it was suppressed with decreasing initial film thickness. The regular pattern was independent of surface wettability of the solid substrate. We ascribe the morphology change to the evaporation-induced surface tension driven convection, which re-arranged the droplet distributions from disordered to flow-induced ordered patterns..
174. Masato Yamamura, Takatoshi Mikuriya, Toshihisa Kajiwara, Kitaro Adachi, Humidity-induced secondary phase separation in a multizone drier, Industrial and Engineering Chemistry Research, 10.1021/ie020053k, 41, 17, 4409-4413, 2002.08, [URL], We demonstrated that an increase in the gas humidity in a two-zone drier enhanced the formation of polymer droplets via a secondary phase separation. Optical microscopy observations revealed that, with an increase in humidity, the separating polymers contacted and coalesced with the neighboring droplets to form characteristic double phase structures superposed in the films. We also demonstrated that the morphology transition was induced by the variation in the phase equilibrium thermodynamics rather than the variation in the solvent drying rate, which was independent of the humidity..
175. K. Funatsu, S. Kihara, M. Miyazaki, S. Katsuki, T. Kajiwara, 3-D Numerical Analysis on the Mixing Performance for Assemblies With Filled Zone of Right-Handed & Left-Handed Double-Flighted Screws and Kneading Blocks in Twin-Screw Extrudes, Polymer Engineering And Science, 10.1002/pen.10983, 42, 4, 707-723, Vol. 42, No. 4, 707-723, 2002.04.
176. Toshihisa Kajiwara, Hideki Tomiyama, Yumi Sueyoshi, Masato Yamamura, Kitaro Adachi, Numerical simulation of extrudate swell problem and evaluation of applicability of viscoelastic constitutive models 1. A study on axisymmetric extrudate swell from a straight die, Nihon Reoroji Gakkaishi, 10.1678/rheology.29.47, 29, 1, 47-52, 2001.12, [URL], Numerical simulations of axisymmetric extrudate swell for a low density polyethyrene (LDPE IUPAC-A) melt were carried out using the K-BKZ model as an integral type and the PTT and Larson models as a differential type. We employed both the reversible and irreversible models for the K-BKZ and Larson models to investigate the effect of reversing deformation on the extrudate swell from a straight die. First, relaxation spectrum and nonlinear parameters in the constitutive equation were determined from dynamic data of linear viscoelasticity and steady shear flow data by using the nonlinear regression, and then they were applied to the simulation of extrudate swell problem. We evaluated the applicability of these models by comparing experiments and simulation for both rheological data and extrudate swell ratio. For the K-BKZ model, the reversible model over-estimates the swell ratio in high shear rate, whereas the irreversible model predicts the experimental data with high accuracy. The irreversible Larson model also shows the good prediction of swell, on the other hand, the reversible one over-estimates the swell and there exists the multiple solutions. For the PTT model, we carried out the simulation using the models with different values of nonlinear parameter, ε, which has the same steady shear flow properties and the different properties of stress relaxation under reversing double step deformation. The model having the larger stress in the stress relaxation under reversing double step deformation shows the larger swell. From these results, we find that the consideration of reversing deformation characteristics is required for the extrudate swell from the straight die..
177. M. Yamamura, T. Nishio, T. Kajiwara, K. Adachi, Effect of stepwise change of drying rate on microstructure evolution in polymer films, Drying Technology, 10.1081/DRT-100105296, 19, 7, 1397-1410, 2001.10, [URL], The effect of the drying rate of the solvent on microstructure evolution in thin films of immiscible polystyrene/polycarbonate blends was investigated by applying a stepwise change in air velocity. The polymer blend was dissolved in tetrahydrofuran and cast on a glass substrate to form a thin liquid film. The drying rate of the solvent was measured by a gravimetric technique, and the phase-separated structure in the film was observed by optical microscopy. The results indicated that cellular structures of droplet arrays were formed in the phases evolved primarily during the early stage of drying, and the droplets then coalesced in the intermediate stage to form bigger droplets. The size of the first evolved phase decreased with increasing time at a high drying rate, whereas larger droplets were obtained with longer high drying rate regimes. These results suggested that the droplets were induced by secondary phase separation which was strongly affected by the drying rate of the solvent..
178. Naoki Satoh, Hideki Tomiyama, Toshihisa Kajiwara, Viscoelastic simulation of film casting process for a polymer melt, Polymer Engineering and Science, 10.1002/pen.10855, 41, 9, 1564-1579, 2001.09, [URL], Numerical simulations of the film casting process were performed using a finite element method for Newtonian and viscoelastic fluids. We simplified the governing equations by the assumption that the stress and velocity gradients in the thickness direction were negligible, and obtained the film thickness and mean value of stress and velocity components in the thickness direction as variables. Viscoelasticity was described by the Larson model with multiple relaxation times. Non-isothermal conditions were considered by applying the time-temperature superposition law. The simulation results for the several kinds of commercial low-density polyethylenes were compared to the experimental data for a laboratory-scale process at 190°C and a commercial-scale process at 310°C. The film width and film thickness distribution at chill roll, and the change of film width were in good agreement for the laboratory-scale process, but the agreement for the commercial-scale process was not as good. In the simulation of the commercial-scale process at high temperature, the value predicted by the use of the viscoelasticity for the original pellet showed poor agreement owing to the change of viscoelasticity in the process. The agreement was improved by the use of the viscoelasticity for the processed resin, which was changed from the original one. Next, viscoelastic effects on neck-in and edge bead phenomena were investigated. The neck-in and edge bead phenomena were considered to be affected by both the uniaxial elongational viscosity and planar elongational viscosity..
179. Masato Yamamura, Satoshi Suematsu, Toshihisa Kajiwara, Kitaro Adachi, Experimental investigation of air entrainment in a vertical liquid jet flowing down onto a rotating roll, Chemical Engineering Science, 10.1016/S0009-2509(99)00387-5, 55, 5, 931-942, 2000.03, [URL], The experimental results of air entrainment into a liquid jet flowing down onto a rotating roller were presented by means of the impinging jet method. The impinging jet was a substitute for a liquid curtain in an industrial coating process. Roll velocity at the onset of air entrainment was measured for different flow rates, nozzle diameters, nozzle heights, impingement angles, viscosities and surface tensions. The results indicated that the inertial force of the jet can delay the onset of air entrainment and that it acts most effectively on the dynamic wetting line when the flow rate is set to make the wetting line locate at the impingement point. The effect of inertial force decreased with further increasing flow rate and the onset velocity reached a constant value which depended only on the physical properties of the fluid. The results of dimensionless analyses indicated that there are two critical values of the Reynolds number, i.e., the one at which the onset velocity has a peak and another above which the onset velocity does not depend on the Reynolds number. In the Reynolds number above the second critical value, major forces acting on the dynamic wetting line were viscous drag force and surface tension, and the flow mechanism at the onset of air entrainment was the same as that in plunging tape flow. Application of the results to curtain coating flow indicated that the critical Reynolds number exists not only in plunging jet flow but also in plunging curtain flow..
180. Yasuhiko Otsuki, Toshihisa Kajiwara, Kazumori Funatsu, Numerical simulations of annular extrudate swell using various types of viscoelastic models, Polymer Engineering and Science, 10.1002/pen.11590, 39, 10, 1969-1981, 1999.01, [URL], In this study, numerical simulations of annular extrudate swell of high density polyethylene (HDPE) were carried out. Some important viscoelastic models, such as the Larson, the PTT and the K-BKZ model, were employed for the swell calculation through various types of dies. These numerical results were compared with the experimental ones. The numerical results of the swell behaviors were very different in each viscoelastic model, while their simple shear flow characteristics were almost the same. As a result, the uniaxial elongational viscosity for large deformation as the steady state region is not important, but the property for relatively small deformation has remarkable effects on the numerical results for the die that have a uniaxial contraction region. Both reversible and irreversible types were tried for the Larson model. It was found that there was a difference between the irreversibility assumption of the K-BKZ model and the Larson model. While there was a serious difference in the response for reversing strain among these viscoelastic models, the response was very important to predict annular extudate swell behavior..
181. Toshihisa Kajiwara, Studies on the numerical simulation of polymeric liquid flow and polymer processing, Nihon Reoroji Gakkaishi, 10.1678/rheology.27.219, 27, 4, 219-226, 1999.01, [URL], This paper summarizes our studies on the numerical flow analysis of polymeric liquids and its application to the industrial problems in the polymer processing. The contents include three parts. The first part is a review about development of numerical technique of viscoelastic flow analysis to obtain the solution at high deformation rate. We used the streamline-upwind (SU) finite element method with the sub-elements for stress components to simulate the extrudate swell at high Weissenberg number (We) . The calculation using the Giesekus model with a single relaxation time was feasible over hundreds of We in the planar and capillary extrude swell, but the calculation was impossible for We > 3 in the annular extrudate swell. We proposed the new technique of under-relaxation method, which introduced the virtual Newtonian stress in order to increase the numerical stability. The calculation by the new technique combined with the SU method was successful in obtaining the solution over hundreds of We in the annular extrudate swell problem. The second part is a review of numerical studies on polymeric liquid flow in the basic flow fields. We performed the viscoelastic flow analysis using the several kinds of constitutive models in the contraction flow and extrudate swell. The simulation results using the viscoelastic model with a single relaxation time were compared with the experimental data of stress field measured by the flow birefringence technique and the agreement better than 20-30% in accuracy was obtained in the lower shear rate region. The simulation results also gave the several explanations about the mechanism of corner vortex and entrance pressure drop in the contraction flow, swelling phenomena in the extudate swell, etc. On the other hand, the simulation using the constitutive models with multiple relaxation times gave the useful information, especially on the effect of material polymer. The last part is application to the industrial problems in polymer processing. The technique of viscoelastic flow analysis was applied to the film casting and the effect of elongational viscosity on the film shape was found. The technique was also applied to the development of prediction of prison formation in blow molding. The viscous non-Newtonian flow analysis was applied to the three-dimensional flow analysis and the evoluation of mixing performance in the twin screw extruder..
182. K. Matsunaga, Toshihisa Kajiwara, K. Funatsu, Numerical simulation of multi-layer flow for polymer melts - A study of the effect of viscoelasticity on interface shape of polymers within dies, Polymer Engineering and Science, 10.1002/pen.10277, 38, 7, 1099-1111, 1998.01, [URL], A two-dimensional simulation was developed for multi-layer confluent viscoelastic flow in dies, using a finite element method. The simulated interface shape was compared with the experimental results of previous researchers, and the simulated results were confirmed. Two-layer and three-layer flows of two or three kinds of viscoelastic fluids were simulated. Fluids with different non-Newtonian viscosities and the first normal stress differences were used. The layer thicknesses in dies are mainly determined by the shear viscosity and less by the elasticity of the fluid. The normal stress difference between the fluids forming an interface may be related to interfacial instability, and normal stresses near the interface were examined. The normal stress difference between both fluids was affected by the first normal stress difference and elongational viscosity..
183. Shuichi Tanoue, Toshihisa Kajiwara, Yoshiyuki Iemoto, Kazumori Funatsu, High weissenberg number simulation of an annular extrudate swell using the differential type constitutive equation, Polymer Engineering and Science, 10.1002/pen.10202, 38, 3, 409-419, 1998, [URL], Annular extrudate swell simulations at high Weissenberg numbers were made using a differential type constitutive equation. The streamline-upwinding method with a sub-element for extra stress components, which is called SU4×4, is one of the best mixed finite element methods for computation of viscoelastic flows. Planar and capillary extrudate swell calculations at high Weissenberg numbers (We>1000) were accomplished by SU4×4. However, annular extrudate swell simulations at high We by SU4×4 were not successful. The calculated We was less than about 4. A new calculation technique using a Newton-Raphson discretization of the equation of motion was developed. This technique is called a "new under-relaxation method." The calculated We of annular extrudate swell simulation by the new under-relaxation method with SU4×4 was about 6∼250 times larger than those by SU4×4. Reasonable calculation results were obtained in an annular flow and a capillary extrudate swell by this method, and the reliability and the utility of the new under-relaxation method are shown. It is now possible to consider the swell shapes of annular extrudate under industrially useful conditions. The calculated swelling ratios were also compared with experimental ones..
184. Yasuhiko Otsuki, Toshihisa Kajiwara, Kazumori Funatsu, Numerical simulations of annular extrudate swell of polymer melts, Polymer Engineering and Science, 10.1002/pen.11761, 37, 7, 1171-1181, 1997.01, [URL], Numerical vlscoelastic simulations were carried out using a K-BKZ type of separable integral constitutive equation. Both reversible and irreversible models were tried for several types of damping functions to calculate the annular extrudate behavior of high-density polyethylene (HDPE). There are two aims in this study; first, to clarify the properties of these dumping functions, and second, to investigate the influence of rheological characteristics on annular extrudate swell. In these numerical simulations, relaxation spectrum and shear viscosity were fixed, and the other characteristics were varied. The reversional response of the damping function mainly has an effect on the magnitude of the area swell even if the die is straight. The irreversible model expresses the experimental results of annular extrudate swell better than the reversible model. The accurate fitting of N1 by the damping model is important for predicting it. The magnitude of N1 predicted from the Wagner exponential model is lower than that of the PSM model, and the area swell shows the same tendency as N1. A modified PSM model that allows the N1 curve to shift can fit the magnitude of area swell. The relationship between the diameter and thickness of the extrudate depends on N2 / N1, and it was estimated by simple linear elasticity of solids. The time-dependent viscosity varies with the type of damping function, and it influences the time-dependent swell..
185. Shuichi Tanoue, Toshihisa Kajiwara, Kazumori Funatsu, Kousuke Terada, Masashi Yamabe, Numerical simulation of blow molding - Prediction of parison diameter and thickness distributions in the parison formation process, Polymer Engineering and Science, 10.1002/pen.10596, 36, 15, 2008-2017, 1996.08, [URL], In our previous study, we calculated the time course of parison length in the parison formation stage, but it could predict only the parison area swell. The next target in our study is to calculate the parison diameter and thickness swell. Annular extrudate swell simulation is necessary for the understanding of various kinds of swelling ratios in blow molding. We have examined three kinds of swells (outer diameter, thickness, and area swells) obtained from simulation results of annular extrudate swell, using the Giesekus model, and have developed a method of predicting parison outer diameter and thickness swell values. The predicted values of parison outer diameters are discussed in comparison with experimental data, and reasonable results are obtained by the proposed method. This prediction method could also be applied to the parison formation process using a parison controller. As a result, it is possible to predict approximately the whole process of parison formation by numerical simulation..
186. Toshihisa Kajiwara, Yuki Nagashima, Yoshio Nakano, Kazumori Funatsu, Numerical study of twin-screw extruders by three-dimensional flow analysis - Development of analysis technique and evaluation of mixing performance for full flight screws, Polymer Engineering and Science, 10.1002/pen.10611, 36, 16, 2142-2152, 1996.08, [URL], We have developed a method for predicting the three-dimensional flow field in the melt conveying zone in counter-rotating and co-rotating twin-screw extruders. We applied this technique to the full flight screws with thin flight width and open C-shaped channels in both rotating type extruders having the same screw configurations. We compared the details of velocity and stress fields, the flow rates of transportation, and various kinds of leakage flows for both rotating type extruders. Also, we obtained the spatial distribution of tracer particles and residence time distribution using a numerical tracer experiment. The flow rate in the transport direction in the co-rotating twin-screw was larger than that in the counter-rotating twin-screw, and this suggested that the latter has higher transport performance when the screws have thin flight width and open C-shaped channels as used in this study. As for the distributive mixing, it was found that the co-rotating twin-screw excels in the area of fluid rearrangement between the two screws and distribution in the rotational direction, while the counter-rotating twin-screw has the desirable characteristic of wide distribution in the axial direction. With regard to dispersive mixing, there was no considerable difference between calculated stress fields in both rotating type extruders..
187. Kazutaka Sakaki, Ryuichi Katsumoto, Toshihisa Kajiwara, Kazumori Funatsu, Three-dimensional flow simulation of a film-casting process, Polymer Engineering and Science, 10.1002/pen.10577, 36, 13, 1821-1831, 1996.07, [URL], Three-dimensional flow simulation of a film-casting process was performed using a finite element method assuming an isothermal and steady Newtonian flow. The simulation was carried out under industrial operation conditions. The neck-in and the edge bead phenomena could be simulated. The effects of draw ratio, air gap length, and die width on these phenomena are discussed. The neck-in and the edge bead phenomena were affected by the draw ratio and air gap length and not by the die width. The neck-in value, which was defined as the difference between the die width and film width at the chill roll, increased with the draw ratio and air gap length..
188. G. Barakos, E. Mitsoulis, C. Tzoganakis, T. Kajiwara, Rheological characterization of controlled-rheology polypropylenes using integral equations, Journal of Applied Polymer Science, 10.1002/(SICI)1097-4628(19960118)59:3<543::AID-APP21>3.0.CO;2-T, 59, 3, 543-556, 1996.01, [URL], Controlled-rheology polypropylene melts were prepared via molecular modification of a commercial polypropylene resin. A peroxide-initiated degradation was performed, resulting in materials with different molecular weight distributions. These resins were subjected to rheological characterization, and an integral constitutive equation of the K-BKZ type was used to study the effect of molecular weight characteristics on their rheological properties. Data for the linear viscoelastic spectrum and shear viscosities was used to obtain the model constants. The same constitutive equation has been used to predict the stress and Trouton ratios for simple shear and simple elongational flows, thus giving a quantitative assessment of the viscoelastic character of the melts. The results show the effect of the molecular modification on the rheological behavior of the melts. Polymers produced at higher peroxide concentrations exhibit reduced viscoelasticity manifested in less shear- and strain-thinning behavior. The present work clearly shows the potential of integral constitutive equations in fitting and interpreting experimental data and, thus, giving a much better understanding of the rheological behavior of commercial polymers..
189. Toshihisa Kajiwara, G. Barakos, E. Mitsoulis, Rheological characterization of polymer solutions and melts with an integral constitutive equation, International Journal of Polymer Analysis and Characterization, 10.1080/10236669508233875, 1, 3, 201-215, 1995.11, [URL], A full nonlinear regression program has been developed in order to determine the appropriate relaxation spectrum and set of material constants for a constitutive equation which can give the best fit to experimental data and predictions for a series of rheological material functions. The constitutive model used is an integral equation of the K-BKZ type suitable for polymer solutions and melts. Available experimental data for determination of the material parameters of the model were dynamic data (storage and loss modulus), steady shear flow data (shear viscosity and first normal stress difference), and steady elongational flow data (uniaxial, planar and biaxial elongational viscosities). The material parameters were determined by a nonlinear least-squares procedure based on the Levenberg-Marquardt method. The program was tested against experimental data of material functions for several polymer solutions and melts. A good fit was obtained between predictions and experimental data. Furthermore, predictions have also been made for unsteady (transient) material functions in shear and elongational flows using the parameters by best-fitting the model, and comparisons have been made with experimental data whenever available. In all cases, the predicted values were in good agreement with the experimental ones..
190. Shuichi Tanoue, Yoshifumi Kuwano, Toshihisa Kajiwara, Kazumori Funatsu, Kousuke Terada, Masashi Yamabe, Numerical simulation of blow molding—Viscoelastic flow analysis of parison formation, Polymer Engineering & Science, 10.1002/pen.760351908, 35, 19, 1546-1554, 1995.01, [URL], The simulation of the parison formation process in blow molding has been studied. The flow field was divided into two regions, namely, the extrudate swell region near the die lip and the parison formation region after the exit swell. In the swell region, we predicted the swelling ratio and residual stress distribution for high Weissenberg numbers for steady planar well using the 1‐mode Giesekus model. In the parison formation region, the flow is assumed to be an unsteady unaxial elongational flow including drawdown and recoverable swell and is modeled using the 10‐mode Giesekus model. We calculated the time course of parison length and thickness distribution, and compare the calculation results of parison length with experimental data. It was found that the predicted values agreed rather well with the experimental values. The calculation results could especially predict the shrink‐back, which is the phenomenon where the parison length becomes shorter after the cessation of extrusion, and it was found tat this was caused by the recoverable swell of the parison, which depends on the tensile stress generation in the die. Various flow rates and die geometries were studied and confirmed the reliability and usefulness of the method..
191. Yoshifumi Kuwano, Toshihisa Kajiwara, Kazumori Funatsu, High Weissenberg number simulation of die swell for differential type viscoelastic model by the streamline-upwind finite element method, Journal of Rheology, 10.1122/1.550571, 38, 3, 755-756, 1994.01, [URL], In order to predict the die swell seen in the actual polymer processing, the planar, the capillary and the annular die swell simulations have been performed by the streamline-upwind finite element method with the subelements for stress components, which was shown effective to calculate up to high Weissenberg number (We) for the entry flow simulation in an earlier study. The calculation using the Giesekus model, which is the differential type viscoelastic model, was found feasible over hundreds of We in the planar and the capillary die swell simulations as long as the primary normal stress difference was not so large. The shape of free surface at high We under the condition of no gravitation once showed the maximum swell and became an equilibrium one after shrinking back a little. This tendency became remarkable for the model with larger We and larger primary normal stress difference. Through the examination of the velocity profile, it was found that the velocity near the free surface was accelerated during the swell after extrusion and was larger than the inside velocity in the neighborhood of the position which showed the maximum swell. Since the accelerated outer fluid dragged the inside fluid, the swelling ratio was supposed to take an equilibrium value after shrinking back a little. Also, as the primary normal stress difference became larger, the axial position of the maximum swell approached the die. This may be due to that the model with the large primary normal stress difference predicts faster swell, because the elastic recovery force after extrusion is large. The axial position of the maximum swell became distant from the die with increasing We. We interpreted that the axial position of the maximum swell shifted downstream as the representative relaxation time was longer, or the velocity became larger. On the other hand, the calculation became impossible for We > 3 in the annular die swell simulation. In order to examine this reason, we performed the calculation for the planar die swell in two different analysis regions, i.e., one being the whole flow region with two singular points and the other, the half flow region with one singular point in consideration of flow symmetry. The calculation in the whole flow region with two singular points was unsuccessful at high We. It seems that the presence of two singular points in the analysis region made it impossible to perform the annular die swell up to high We simulation..
192. Shuichi Tanoue, Toshihisa Kajiwara, Kazumori Funatsu, Numerical study on abrupt contraction flow of viscoelastic fluids including the inertia effect, Journal of Rheology, 10.1122/1.550570, 38, 3, 754-755, 1994.01, [URL], The viscoelastic flow in a planar abrupt contraction was analyzed including the inertia effect, and the effects of inertia and viscoelasticity on the flow were studied. The Galerkin finite element method was employed as the numerical method. The constitutive model was the simplified Criminale-Ericksen-Filbey (CEF) model which expressed the extra stresses as an explicit function of velocity and deformation rate. We studied the effects of the Reynolds number, the Weissenberg number (the primary normal stress difference) and the elongational viscosity individually on the re-entrant corner vortex and the entrance pressure drop. As a result, we found the following: (1) as the primary normal stress difference increases, the corner vortex grows up but the entrance pressure drop slightly decreases. (2) The inertia effect reduces the comer vortex produced by the viscoelasticity and increases the entrance pressure drop. (3) The flow fields are significantly influenced by the viscoelasticity in the low flow rate region but become to be dominated by the inertia with increasing flow rate. (4) Both the vortex intensity and the entrance pressure drop for the fluid with strain-thickening elongational viscosity are larger than those for the fluid with strain-thinning elongational viscosity..
193. T. Kajiwara, S. Ninomiya, Y. Kuwano, K. Funatsu, Numerical simulation of converging flow of polymer melts through a tapered slit die, Journal of Non-Newtonian Fluid Mechanics, 10.1016/0377-0257(93)80067-L, 48, 1-2, 111-124, 1993.07, [URL], Numerical simulation of the converging flow of polymer melts through a tapered slit die was performed with the finite element method using two kinds of constitutive equations: the Phan Thien-Tanner (PTT) and the Giesekus models with a single relaxation time. The calulated stress distributions assuming planar flow were compared with the experimental values measured by the flow birefringence technique. The model parameters were determined from the experimental data of shear viscosity and the primary normal stress difference by fitting the models. The PTT model fitted the experimental data better than the Giesekus model within the range of experimental shear rates, and therefore the numerical results of stress distribution for the PTT model agreed with the experimental values better than those for the Giesekus model. The difference between the calculated and experimental local stresses for the PTT model was less than 20% of the values at the downstream slit wall and it can be concluded that the PTT model is useful for the simulation of converging flow of polymer melts in the low shear rate region. Moreover the average stresses over the width of the channel in the fully developed rectangular channel flow were compared with the experimental values in order to assess the effect of side wall in the experiment. As a result, the average stresses in the rectangular channel flow were closer to the experimental values than those in the planar flow. It was found that the numerical results may be closer to the experimental results by considering the three-dimensional flow..
194. Yoshifumi Kuwano, Toshihisa Kajiwara, Kazumori Funatsu, High Weissenberg Number Simulation of Die Swell for Differential Type Viscoelastic Model by the Streamline-Upwind Finite Element Method, Nihon Reoroji Gakkaishi, 10.1678/rheology1973.21.3_130, 21, 3, 130-137, 1993.01, [URL], In order to predict the die swell seen in the actual polymer processing, the planar, the capillary and the annular die swell simulations have been performed by the streamline-upwind finite element method with the sub-elements for stress components, which was shown effective to calculate up to high Weissenberg number (We) for the entry flow simulation in an earlier study. The calculation using the Giesekus model, which is the differential type viscoelastic model, was found feasible over hundreds of We in the planar and the capillary die swell simulations as long as the primary normal stress difference was not so large. The shape of free surface at high We under the condition of no gravitation once showed the maximum swell and became an equilibrium one after shrinking back a little. This tendency became remarkable for the model with larger We and larger primary normal stress difference. Through the examination of the velocity profile, it was found that the velocity near the free surface was accelerated during the swell after extrusion and was larger than the inside velocity in the neighborhood of the position which showed the maximum swell. Since the accelerated outer fluid dragged the inside fluid, the swelling ratio was supposed to take an equilibrium value after shrinking back a little. Also, as the primary normal stress difference became larger, the axial position of the maximum swell approached the die. This may be due to that the model with the large primary normal stress difference predicts faster swell, because the elastic recovery force after extrusion is large. The axial position of the maximum swell became distant from the die with increasing We. We interpreted that the axial position of the maximum swell shifted downstream as the representative relaxation time was longer, or the velocity became larger. On the other hand, the calculation became impossible for We>3 in the annular die swell simulation. In order to examine this reason, we performed the calculation for the planar die swell in two different analysis regions i. e. one being the whole flow region with two singular points and the other, the half flow region with one singular point in consideration of flow symmetry. The calculation in the whole flow region with two singular points was unsuccessful at high We. It seems that the presence of two singular points in the analysis region made it impossible to perform the annular die swell up to high Wesimulation..
195. Shuichi Tanoue, Toshihisa Kajiwara, Kazumori Funatsu, Numerical Study on Abrupt Contraction Flow of Viscoelastic Fluids Including the Inertia Effect, Nihon Reoroji Gakkaishi, 10.1678/rheology1973.21.3_123, 21, 3, 123-129, 1993.01, [URL], The viscoelastic flow in a planar abrupt contraction was analyzed including the inertia effect, and the effects of inertia and viscoelasticity on the flow were studied. The Galerkin finite element method was employed as the numerical method. The constitutive model was the simplified Criminale-Ericksen-Filbey (CEF) model which expressed the extra stresses as an explicit function of velocity and deformation rate. We studied the effects of the Reynolds number, the Weissenberg number (the primary normal stress difference) and the elongational viscosity individually on the re-entrant corner vortex and the entrance pressure drop. As a result, we found the following; 1) as the primary normal stress difference increases, the corner vortex grows up but the entrance pressure drop slightly decreases. 2) The inertia effect reduces the corner vortex produced by the viscoelasticity and increases the entrance pressure drop. 3) The flow fields are significantly influenced by the viscoelasticity in the low flow rate region but become to be dominated by the inertia with increasing flow rate. 4) Both the vortex intensity and the entrance pressure drop for the fluid with strain-thickening elongational viscosity are larger than those for the fluid with strain-thinning elongational viscosity..
196. Toshihisa Kajiwara, Yoshifumi Kuwano, Masahiko Sameshima, Kazumori Funatsu, Numerical study on extrudate swell of polymer melts in extrusion from various dies, Memoirs of the Kyushu University, Faculty of Engineering, 51, 3, 145-162, 1991.09, This paper describes a numerical study on the extrudate swell of polymer melts in extrusion from various kinds of dies in shape, namely parallel plate, capillary, annular and converging dies. The Oldroyd-B, the Giesekus type and the Phan Thien-Tanner type models were used as the constitutive equations of polymer melts. Swelling ratio, shape of the free surface, and distributions of velocity, stress and pressure were calculated by the ordinary Galerkin's finite element method and the streamline-upwind finite element method. The calculated results for three kinds of viscoelastic models and the Newtonian fluid showed that the swelling phenomenon is closely related to the magnitude of the primary normal stress difference and the shear-thinning effect of shear viscosity. It was also found that the swelling mechanism can be understood mainly from the viewpoint of stress. From the results for annular dies, the difference of shape of free surface between annular extrudate and parallel plate or capillary extrudate was clarified. Furthermore the entrance effect on extrudate swell was found in the low deformation rate from the results for converging dies..
197. Toshihisa Kajiwara, Shuichi Tanoue, Yoshifumi Kuwano, Kazumori Funatsu, Numerical Simulation of Fiber Orientation and Dispersion for Fiber-Filled Polymer Melts, Transactions of the Japan Society of Mechanical Engineers Series B, 10.1299/kikaib.57.2740, 57, 540, 2740-2747, 1991.01, [URL], This paper describes the numerical simulation of the fiber orientation and dispersion for fiber-filled polymer melts in entry and exit flows. First we calculated the viscoelastic flow field of matrix fluids. The higher elastic fluid shows the larger normal stress difference in a die and swells more after extrusion. The velocity profile in the die depends on the shear viscosity, and the shear-thinning viscosity makes the swell smaller. Next we calculated the fiber orientation and dispersion using the velocity fields of the matrix fluids. The fibers tend to array along the streamlines in acceleration flow and perpendicularly to the flow direction in deceleration flow. In the shear flow, the long fibers array along the streamline and the short fibers rotate. The fiber orientation state is less affected by the flow field with increasing interaction between fibers. The fiber dispersion state depends on the inlet boundary of the flow field..
198. Toshihisa Kajiwara, Yukihiro Yoshida, Kazumori Funatsu, Numerical simulation of die swell of polymer melts, Proceedings of the 39th Japan National Congress for Applied Mechanics 1989 - NCTAM-39
Theoretical and Applied Mechanics
, 39, 337-343, 1990.12, Numerical simulation of die swell of polymer melts was undertaken with Galerkin's finite element method using three kinds of constitutive equations: the Giesekus type model, the Phan Thien-Tanner type model, and the Oldroyd-B model. The calculated swelling ratios for these models showed that the magnitude of the primary normal stress difference and the shear-thinning effect of viscosity are closely involved in the swelling phenomenon. From the calculated stress distributions it was also found that the swelling mechanism can be understood mainly from the viewpoint of stress. The calculated stress distributions for the Giesekus type and the Phan Thien- Tanner type models were compared with experimental data for a polypropylene melt measured by the flow birefringence technique and they were at least qualitatively in agreement. Ultimately the reliability of computer simulation and the constitutive equations was proved for polymer melt flow in lower shear rate region..
199. K. Funatsu, T. Kajiwara, Y. Shiraishi, Stress distribution and drag force in creeping flow around a falling sphere. Measurement by a flow-birefringence technique, International chemical engineering, 28, 4, 634-641, 1988.10, The distributions of the primary normal stress difference and the shear stress in creeping flow around a falling sphere were measured by a transmitted-light, flow-birefringence technique. Both distributions were qualitatively reasonable, but were considerably different from the exact solutions for a Newtonian fluid with the same viscosity in the vicinity of the sphere, because of the elastic effect. The drag force acting on the sphere was calculated and used to evaluate the measurements quantitatively..
200. K. Funatsu, T. Kajiwara, APPROXIMATE ANALYSIS OF AN AXISYMMETRIC FIELD OF STRESS BY A TRANSMITTED-LIGHT, FLOW-BIREFRINGENCE TECHNIQUE., International chemical engineering, 28, 3, 504-511, 1988.01, A method was devised for analyzing approximately an axisymmetric field of stress, based on the assumptions that the angle of extinction obtained from the isoclinic pattern was approximately equal to the inclination of the principal axis of a refractive-index ellipsoid, and that the phase difference is dependent only on the local values of the double refractive index. An approximate equation was used to find the local values of the primary double-refractive index. The method was applied to the analysis of the stresses associated with flow around a sphere as an example with axisymmetry. 8 Refs..
201. Kazumori Funatsu, Toshihisa Kajiwara, Yukihiro Shiraishi, Yuji Tsuruta, Stress Distribution around the Bubbles Rising Continuously along One Vertical Axis in a Viscoelastic Fluid, Nihon Reoroji Gakkaishi(Journal of the Society of Rheology, Japan), 10.1678/rheology1973.15.3_153, 15, 3, 153-157, 1987.01, [URL], The stress distribution around the bubbles rising continuously along one vertical axis in a viscoelastic fluid was measured by transmitted light flow birefringence technique. A new method was developed for analyzing approximately an axisymmetric stress field. The method can be applied in the either case that the primary double refractive indices (primary stress differences) become larger toward the central axis or not. In order to evaluate quantitatively whether the method is effective for the analysis of the flow field around a single rigid sphere, the value of drag force acting on the sphere calculated from the measured stress distribution was compared with the directly measured value. The calculated values were about 20% larger than the measured values. By using this method, distributions of the primary normal stress difference and the shear stress rrz could be obtained in the flow field around the bubbles rising along one vertical axis. Measurements were performed for three kinds of distance between the bubbles. Observed features of the distributions were consistent with the expected flow field. The quantitative evaluation of the method for the experimental result is still to be investigated especially in the region between the bubbles where the primary double refractive indices don’t become larger toward the central axis..
202. Kazumori Funatsu, Toshihisa Kajiwara, Yukihiro Shiraishi, Hiroshi Matsuo, Stress Distribution in Creeping Flow of a Viscoelastic Fluid around a Single Bubble, Nihon Reoroji Gakkaishi(Journal of the Society of Rheology, Japan), 10.1678/rheology1973.15.3_147, 15, 3, 147-152, 1987.01, [URL], The stress distribution in creeping flow of a viscoelastic fluid around a single bubble was measured by the transmitted light flow birefringence technique. Distributions of the primary normal stress difference rzz-rrr and the shear stress rrz could be obtained in the flow field around a growing and rising bubble. Moreover, the difference between the principal value of stress directed in the tangential direction and that directed in the normal direction on the bubble surface could be obtained. Observed features of all the distributions were consistent with the viscoelastic behavior of the fluid. The measured stress distribution around the freely rising bubble with a constant velocity was compared with the exact solution for a Newtonian fluid. In contrast with the theoretical result, the distribution of the absolute values of stress is not symmetrical with respect to the horizontal cross-sectional plane of the bubble. The measured values were larger downstream than upstream, especially at the region close to the bubble. This asymmetry is probably due to the viscoelastic property of the fluid. It was also found that the stress distributions for the rising bubble and for the falling rigid sphere were similar to each other except in the region close to the surfaces. The values of rrz on the side of the bubble were smaller than that of the rigid sphere because the shear stress at the gas-liquid interface was so small that it could be disregarded..
203. Kazumori Funatsu, Toshihisa Kajiwara, An Approximate Analysis of Axisymmetric Stress Field by Using Transmission Light Flow Birefringence Technique, kagaku kogaku ronbunshu, 10.1252/kakoronbunshu.12.575, 12, 5, 575-581, 1986.01, [URL], A method was devised for analyzing an approximately axisymmetric stress field. It was assumed in the method that the extinction angle obtained from the isoclinic pattern is almost equal to the inclination of the principal axis of a refractive index ellipsoid and that the phase difference is dependent only on the local values of the double refractive index. An approximate equation was employed to analyze the local values of the primary double refractive index. This method was applied to analysis of stress for the flow around a sphere as an example of an axisymmetric flow field. According to the results of numerical calculation of the extinction angle and the optical equation, it was found that the above assumptions were reasonable. Values of the primary refractive index obtained by using the equation were somewhat lower than the actual value. It may be concluded that the method is effective for approximate stress analysis of axisymmetric flow fields with double refractive indices rising to the axis, if suitable correction for double refractive indices is made..
204. K. Funatsu, T. Kajiwara, An approximate analysis of axisymmetric stress field by using transmission light flow birefringence technique., kagaku kogaku ronbunshu, 12, 5 , Sep. 1986, p.575-581., 1986.01, A method for analyzing an approximately axisymmetric stress field was established. The extinction angle obtained from the isoclinic pattern was taken to be almost equal to the inclination of the principal axis of a refractive index ellipsoid and the phase difference to be dependent only on local values of the double refractive index. Analysis of the local values of the primary double refractive index was made using an approximate equation. The method was applied to stress analysis of the flow around a sphere constituting an example of an axisymmetric flow field. The assumptions cited were shown to be reasonable and the method expressed effective for approximate stress analysis of axisymmetric flow fields with double refractive indices rising to the axis, if suitable correction for such indices is made. (P.J.B.).
205. Kazumori Funatsu, Toshihisa Kajiwara, Hiroyuki Nishimura, Measurement of flow Characteristics of Viscoelastic Fluid by Mach-Zehnder Interferometry, Nihon Reoroji Gakkaishi(Journal of the Society of Rheology, Japan), 10.1678/rheology1973.14.1_30, 14, 1, 30-36, 1986.01, [URL], Mach-Zehnder interferometry, as applied to the stress analysis of solid materials, was employed to investigate the flow of viscoelastic fluids. With this method, secondary principal values of a refractive index ellipsoid can be measured because a reference light is used. This is in contrast to the birefringence method, in which only the difference of principal values can be evaluated. A Poiseuille flow between two parallel plates was selected as a flow field. Schemes for measurement of direct and transverse stress optical coefficients, C1and C2, and absolute values of normal stresses were derived for each case where either poralized or nonpolarized light is led through the test section in the flow direction, the direction perpendicular to the shear plane, or the neutral direction. Such quantities can be evaluated if the phase difference can be measured as a function of shear stress and pressure on the wall and a stress optical coefficient C1-C2is known in advance. Preliminary experiments for polyethylene and polystyrene melts were carried out with the polarized light perpendicular to the shear plane. However measurements accurate enough to allow evaluation of the normal stresses etc. have not been attained in this study..
206. Kazumori Funatsu, Toshihisa Kajiwara, Yukihiro Shiraishi, Stress Distribution in Creeping Flow around a Falling Sphere and Its Drag Force
—Measurement by flow birefringence technique—, kagaku kogaku ronbunshu, 10.1252/kakoronbunshu.12.582, 12, 5, 582-588, 1986.01, [URL], Distributions of the primary normal stress difference and shear stress in creeping flow around a falling sphere were measured by the transmission light flow birefringence technique. Both distributions measured were found to be reasonable qualitatively and were considerably different in the neighborhood of the sphere from exactly analyzed values for a Newtonian fluid with the same value of viscosity, because of the elastic effect. The drag force acting on the sphere was calculated and used for quantitative evaluation of the measured values. The value calculated from the measured stress distributions was found to be close to the directly measured value, if suitable correction is made. It may be concluded that the transmission light flow birefringence technique can be employed for analyzing the stress distributions in axisymmetric flow fields with double refractive indices rising to the axis..

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