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A Study of Magnetic Fluid Seals for Blood Sealing
Jun TOMIOKA,Akira FUKAISHI,Takashi OHBA 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
Magnetic fluid seals are used in a wide variety of gas and dust sealing applications. However, it is difficult to seal for liquid because of its characteristic. This study will be a basic guide for a magnetic fluid seal for liquid, especially for blood to be practically used in medical instruments such as rotary blood pumps by clarifying its seal properties. Sealing pressure test, durability test, and hemolysis test have been conducted for this seal. In this study, magnetic fluid, sealing fluid, eccentricity ratio, revolution speed were selected as parameters. As results of the tests, it has been found that the properties of magnetic fluid seal depend on the solvent and the saturation magnetization of magnetic fluid. Therefore, the selection of magnetic fluid is important for this seal. It also has been found that eccentricity ratio of the shaft caused harmful effect for seal propertles. In conclusion, it has been showed that magnetic fluid seals could be possibly used in medical instruments such as blood pumps when blood come in contact with magnetic fluids.
The Effect of the Aging of Red Blood Cells on Rheological Properties and Hemolysis
Jun TOMIOKA,Kazuhiro MOTOKUBO,Hisayoshi WATANABE 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10
It is well known that red blood cells (RBCs) are suffered from chronic stresses in systemic circulation. The objective of this study is to clarify the effect of the aging of RBCs on rheological properties and hemolysis. Initially, RBCs age fractionation was performed by using a high-speed centrifugation (15[min] at 1500[G]), then young and aged RBCs were suspended in plasma to adjust the hematocrit level of 40[%]. After this pretreatment, the viscosity was measured by using a capillary type and a cone-plate type viscometers, respectively, and the hemolysis test was carried out by a seesaw type shaker. Results from these experiments showed that the viscosity of the aged RBCs measured by the capillary viscometer was increased by 10[%] as compared with that of the young RBCs. Under the condition of all shear zones, the viscosity of the aged RBCs was increased in case of using the cone-plate type viscometer. And the hemolytic level was increased twice as the aging. The data obtained in this study indicated that the ability of aggregation of RBCs was increased and the deformability of RBCs' membrane got lower with the aging. Furthermore, it was exhibited that the fragility of RBCs' membrane was increased with the aging.
EMI Prediction and Reduction of Zero-Crossing Noise in Totem-Pole Bridgeless PFC Converters
Baihua Zhang,Qiang Lin,Jun Imaoka,Masahito Shoyama,Satoshi Tomioka,Eiji Takegami 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter iscomprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source,and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presentedto investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoreticalanalysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method isproposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-basedtotem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.
EMI Prediction and Reduction of Zero-Crossing Noise in Totem-Pole Bridgeless PFC Converters
Zhang, Baihua,Lin, Qiang,Imaoka, Jun,Shoyama, Masahito,Tomioka, Satoshi,Takegami, Eiji The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter is comprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source, and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presented to investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoretical analysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method is proposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-based totem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.
Yijie Guo,Tomokazu Fukuda,Shuichi Nakamura,Lanlan Bai,Jun Xu,Kengo Kuroda,Rintaro Tomioka,Hiroshi Yoneyama,Emiko Isogai 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.2
Leptospiral lipopolysaccharide (L-LPS) has shown potency in activating toll-like receptor 2 (TLR2) in pig fibroblasts (PEFs_NCC1), and causes the expression of proinflammatory cytokines. However, the stimulation by L-LPS was weak eliciting the function of TLR2 sufficiently in pig innate immunity responses during Leptospira infection. In this study, the immune response of pig embryonic fibroblast cell line (PEFs_SV40) was investigated and was found to be the high immune response, thus TLR2 is the predominate receptor of L-LPS in pig cells. Further, we found a strategy using the antibody against L-LPS, to prevent L-LPS interaction with TLR2 in pig cells which could impact on immune activation.
Guo, Yijie,Fukuda, Tomokazu,Nakamura, Shuichi,Bai, Lanlan,Xu, Jun,Kuroda, Kengo,Tomioka, Rintaro,Yoneyama, Hiroshi,Isogai, Emiko Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.2
Leptospiral lipopolysaccharide (L-LPS) has shown potency in activating toll-like receptor 2 (TLR2) in pig fibroblasts (PEFs_NCC1), and causes the expression of proinflammatory cytokines. However, the stimulation by L-LPS was weak eliciting the function of TLR2 sufficiently in pig innate immunity responses during Leptospira infection. In this study, the immune response of pig embryonic fibroblast cell line (PEFs_SV40) was investigated and was found to be the high immune response, thus TLR2 is the predominate receptor of L-LPS in pig cells. Further, we found a strategy using the antibody against L-LPS, to prevent L-LPS interaction with TLR2 in pig cells which could impact on immune activation.