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Zinc-containing tricalcium phosphate and related materialsfor promoting bone formation
Atsuo Ito,Makoto Otsuka,Haruo Kawamura,Masako Ikeuchi,Hajime Ohgushi,Yu Sogo,Noboru Ichinose 한국물리학회 2005 Current Applied Physics Vol.5 No.5
Calcium phosphate is a suitable carrier of zinc, an essential element that has stimulatory effects on bone formation in vitro and in vivo as well as an inhibitory effect on osteoclastic bone resorption in vitro. The highest zinc content is attained in b-tricalcium phosphate, where the zinc content reaches 6 wt%. Both rat and human bone marrow cells (BMCs) cultured on zinc-containing b-tricalcium phosphate and hydroxyapatite composite ceramics differentiated more than BMCs cultured on zinc-free composite ceramics in the presence of b-glycerophosphate and dexamethasone. The acceptable dose of zinc was higher for human BMCs than for rat BMCs. The solubility of ZnTCP, which contains a nontoxic level of zinc, decreased to 52–92% that of pure TCP in the pH range of 5.0–7.4. However, the resorbed volume of ZnTCP was much lower than that expected from the in vitro solubility of ZnTCP, becoming as low as 26–20% that of TCP, which indicates that the reduction in the resorbability of ZnTCP would be attributable principally to its lowered cellular activation property relative to that associated with pure TCP. Probably due to the lowered cellular activation property associated with ZnTCP, bone loss at the bone-implant interface was significantly arrested in the longterm implantation of ZnTCP/HAP. The intramuscular injection of ZnTCP powder is effective in increasing bone mineral density in the vicinity of the injected site in osteopenic animals. All these findings suggest that zinc-containing calcium phosphate is a biomaterial that promotes bone formation.
Polymer structure and properties in micro- and nanomolding process
Hiroshi Ito,Hajime Suzuki,Kunihiko Kazama,Takeshi Kikutani 한국물리학회 2009 Current Applied Physics Vol.9 No.2
Injection molding of thin-wall parts with micro/nano-scale patterns using various polymers was performed to clarify the processability and surface replication of molded parts. Effects of process conditions on processability, higher-order structure and surface properties of molded parts were evaluated. The optical anisotropy in the vicinity of the gate became higher than at any other positions. The height replication ratio of surface patterns increased with increasing injection speed, holding pressure, injection temperature and mold temperature. In the case of nanomolding, negative birefringence toward the flow direction appeared higher than at the skin–shear region from the observation of skin–shear and core structure inside molded parts. Thus, the molecular orientation axis was oriented along the thickness direction because of deformation during the demolding process. Thermal stability of nano-surface patterns was influenced by the size of surface features and internal higher-order structure.
Arai Hikaru,Asami Koki,Ito Hajime,Katayama Noboru 한국물리학회 2022 Current Applied Physics Vol.39 No.-
Catalyst layers of proton exchange membrane fuel cells (PEMFC) are formed by electrospray deposition (ESD) method. The cathode catalyst layers are formed and characterized by varying the settings of the system, such as flow rate, applied voltage and the distance between the capillary and the substrate. The dryness of the aggregates during deposition is evaluated using the Damkh¨oler number (Da), and the structure of the catalyst layer is observed using SEM, which shows that the catalyst layer is porous when dry and non-porous when insufficiently dry. In the case of insufficient drying, the structure changed significantly depending on the position. Single cell tests show that the maximum power density varies from 105 to 253 mWcm-2 depending on the settings, even with the same catalyst ink and the same amount of platinum. Electrochemical impedance spectroscopy shows that the charge transfer and mass transport resistances tend to decrease with increase in Da.
Potentiality of Oxygenated Fuels on Soot-Free Diesel Combustion
Takaaki Kitamura,Takayuki Ito,Jiro Senda,Hajime Fujimoto 한국자동차공학회 2001 한국자동차공학회 Symposium Vol.- No.-
Fuel/air equivalence ratio '??' and temperature 'T' have a significant effect on the quality of particulate formation. In other words, it is probable that smokeless diesel combustion is realized if ?? and T inside the burning plume could be controlled based on the dependence of those on soot formation. The purpose of this work is to extract smokeless ?? - T conditions for various kinds of fuels, including paraffinic hydrocarbon, aromatic hydrocarbon, and oxygenated hydrocarbon, and to discuss a possibility of smokeless diesel combustion avoiding a soot formation region on ?? - T diagram. Sooting ?? - T map, which shows the tendency to generate soot particles as a function of ?? and T, was made using a detailed soot formation model. The model was based on a combination of a detailed reaction mechanism to calculate the gas phase chemistry and a detailed kinetic soot model based on the method of moments. It was found that smokeless ?? - T condition becomes more widespread especially for oxygenated fuels, due to the notable reduc-tion of both acetylene and PAHs. As a result of this work, a new concept for diesel combustion has been developed that utilizes the smokeless nature of oxygenated fuels.
A simplified PCR assay for fast and easy mycoplasma mastitis screening in dairy cattle
Hidetoshi Higuchi,Hidetomo Iwano,Kazuhiro Kawai,Takehiro Ohta,Tetsu Obayashi,Kazuhiko Hirose,Nobuhiko Ito,Hiroshi Yokota,Yutaka Tamura,Hajime Nagahata 대한수의학회 2011 Journal of Veterinary Science Vol.12 No.2
A simplified polymerase chain reaction (PCR) assay was developed for fast and easy screening of mycoplasma mastitis in dairy cattle. Species of major mycoplasma strains [Mycoplasma (M.) bovis, M. arginini, M. bovigenitalium, M. californicum, M. bovirhinis, M. alkalescens and M. canadense] in cultured milk samples were detected by this simplified PCR-based method as well as a standard PCR technique. The minimum concentration limit for detecting mycoplasma by the simplified PCR was estimated to be about 2.5 × 10^3 cfu/mL and was similar to that of the standard PCR. We compared the specificity and sensitivity of the simplified PCR to those of a culture method. Out of 1,685 milk samples cultured in mycoplasma broth, the simplified PCR detected Mycoplasma DNA in 152 that were also positive according to the culture assay. The sensitivity and specificity of the simplified PCR were 98.7% and 99.7%, respectively, for detecting mycoplasma in those cultures. The results obtained by the simplified PCR were consistent with ones from standard PCR. This newly developed simplified PCR, which does not require DNA purification, can analyze about 300 cultured samples within 3 h. The results from our study suggest that the simplified PCR can be used for mycoplasma mastitis screening in large-scale dairy farms.