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排序方式: 共有458条查询结果,搜索用时 776 毫秒
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Noriaki Takagi Yoshinobu Izumi Kimiko Ema Tadashi Yamamoto Kazushige Nishizawa 《溶剂提取与离子交换》2013,31(6):1461-1471
ABSTRACT Dicyclohexano- 18-crown-6 (DC18C6), dissolved in chloroform, 1-octanol, toluene or cyclohexane, was irradiated by 60Co γ-rays. Radiolytic destruction of DC18C6, measured by gas chromatography, decreased in the order: chloroform > cyclohexane > 1-octanol > toluene. Distribution coefficients in the solvent extraction of strontium from nitric acid solution were measured. These distribution coefficients were minimally affected by γ-irradiation in toluene solution, but decreased with the absorbed dose in chloroform solution. It was suggested that the distribution coefficient for the liquid-liquid extraction system was influenced by radiolytic products. The effect of radiolytic products on the distribution coefficients was evaluated by considering DC18C6 remaining in the organic phase after irradiation. The distribution coefficient measured for the organic phase with radiolytic products was larger than that without radiolytic products. The radiolytic products were thus shown to contribute to the increase in the distribution coefficient. 相似文献
24.
Sharmy Saimon Mano Koki Kanehira Akiyoshi Taniguchi 《International journal of molecular sciences》2013,14(7):13154-13170
The innate immune response is the earliest cellular response to infectious agents and mediates the interactions between microbes and cells. Toll-like receptors (TLRs) play an important role in these interactions. We have already shown that TLRs are involved with the uptake of titanium dioxide nanoparticles (TiO2 NPs) and promote inflammatory responses. In this paper, we compared role of cellular uptake and inflammatory response via TLR 4 to lipopolysaccharide (LPS) and TiO2 NPs. In the case of LPS, LPS binds to LPS binding protein (LBP) and CD 14, and then this complex binds to TLR 4. In the case of TiO2 NPs, the necessity of LBP and CD 14 to induce the inflammatory response and for uptake by cells was investigated using over-expression, antibody blocking, and siRNA knockdown experiments. Our results suggested that for cellular uptake of TiO2 NPs, TLR 4 did not form a complex with LBP and CD 14. In the TiO2 NP-mediated inflammatory response, TLR 4 acted as the signaling receptor without protein complex of LPS, LBP and CD 14. The results suggested that character of TiO2 NPs might be similar to the complex of LPS, LBP and CD 14. These results are important for development of safer nanomaterials. 相似文献
25.
T Kobayashi S Urakami Y Hirayama T Yamamoto M Nishizawa T Takahara Y Kubo O Hino 《Canadian Metallurgical Quarterly》1997,88(3):254-261
Membrane conductances during hypoosmotic swelling were characterized in rat astrocytes in primary tissue culture. Using whole cell patch clamp techniques, mean +/- SEM cell conductance in isoosmotic phosphate-buffered saline (PBS) was 55.6 +/- 5.8 pS/pF. Cell conductance (mean +/- SEM) increased from this initial value to 187 +/- 46%, 561 +/- 188%, and 1216 +/- 376% within 9 min of exposure to 220 mOsm, 190 mOsm, and 145 mOsm PBS, respectively. With each of these hypoosmotic exposures, no change occurred in membrane capacitance. When CsCl replaced KCl in the microelectrode solution, a similar conductance increase was obtained at each osmolality. However, when gluconate salts were used in place of chloride salts in the electrode solution, no significant conductance increase was observed with 190 mOsm PBS. With a KCl microelectrode solution, all conductance increase which occurred in 190 mOsm PBS was inhibited by 200 microM niflumic acid, but not by 5 mM BaCl(2). Both niflumic acid and BaCl(2) inhibited 60-80% of the conductance increase of cells in 145 mOsm PBS. Using a microelectrode solution containing taurine as the major anion, membrane conductance increased 5-fold when cells were placed in 250 mOsm medium. This conductance increase was completely inhibited by 200 microM niflumic acid. Thus, independent chloride and potassium conductances are activated by hypoosmotic swelling of cultured astrocytes while plasma membrane area is unaltered. The chloride conductance pathway is activated at a significantly lower degree of hypoosmotic exposure than that which activates the potassium pathway and may be permeable to anionic taurine. These conductance pathways may mediate diffusive loss of potassium, chloride, and taurine from these cells during volume regulation following hypoosmotic swelling. 相似文献
26.
A freckle criterion for the solidification of superalloys with a tilted solidification front 总被引:3,自引:0,他引:3
Wan-Hong Yang John J. deBarbadillo Koki Morita T. Suzuki Wei Chen Keh-Minn Chang 《JOM Journal of the Minerals, Metals and Materials Society》2004,56(9):56-61
A freckle criterion developed from M.C. Fleming’s macrosegregation theory was extended to consider the effect of the slope
of the solidification front. Such slopes are always associated with the remelting of alloy ingots and are frequently encountered
in the directional solidification of single crystal and directionally solidified blades. When experimental verification of
the criterion was carried out using the horizontal directional solidification method, dendrite growth rate was found to be
a key factor in the formation of freckles. The criterion derived considering the slope of the solidification front describes
the occurrence of freckles relatively well. Critical values for freckle formation were obtained for a few nickel-base superalloys.
For more information, contact Wan-Hong Yang, Special Metals Corporation, 3200 Riverside Dr., Huntington, WV 25705. 相似文献
27.
We hypothesize that the interaction between protein kinase C (PKC) and nitric oxide (NO) plays a role in the modulation of cerebral vascular tone, and the disturbance of this interaction following subarachnoid hemorrhage (SAH) results in vasospasm. To prove this hypothesis with direct evidence, PKC activities of smooth muscle cells of canine basilar arteries in the control and in the SAH groups were measured by an enzyme immunoassay method. N omega-nitro-L arginine (L-NA), an inhibitor of NO production, enhanced PKC activity. This enhancement was inhibited neither by 8-bromo-guanosine 3',5'-cyclic monophosphate (8-bromo-cGMP) nor SIN-1, a NO releasing agent. PKC activity in the SAH was significantly higher than in the control; however, no further enhancement was produced with L-NA. In the SAH, PKC activity was not inhibited either by 8-bromo-cGMP or SIN-1. We conclude that NO maintains an appropriate vascular tone through inactivation of PKC, and that this effect is disturbed following SAH, resulting in PKC-dependent vascular contraction, such as vasospasm. On the other hand, once PKC has been activated, NO precursors do not inhibit PKC. These facts indicate NO inactivates PKC through the inhibition of phosphatidylinositol breakdown. 相似文献
28.
Y Tamagawa K Kitamura H Hagiwara T Ishida M Nishizawa T Saito Y Iwamoto 《Canadian Metallurgical Quarterly》1997,106(4):338-342
In preparation for the introduction of Project 2000 throughout Scotland, a need was identified to monitor the quality of the learning environment for student nurses in the practice setting. No mechanism existed to measure quality and standards, and a group was formed to devise, pilot and implement an educational audit tool which could address these requirements, since limited information was available in the literature. Using this tool, the group subsequently examined the learning opportunities available, concentrating on the physical environment, the learning climate/environment, and the students' perceptions of the learning environment within the practice setting, across hospital and community sectors, including residential accommodation and nurseries, in the wide geographical area covered by the health board. This paper describes the process by which the tool was formulated, tested and implemented, the problems encountered, and the improvements in communications between teaching and clinical staff, leading to improved opportunities for the provision of excellence in patient care. 相似文献
29.
K Nishizawa T Maruyama M Takayama K Iwai Y Furuya 《Canadian Metallurgical Quarterly》1995,55(11):763-768
Tissue or organ doses related to radiological risk were determined for four different types of CT scanners with a spiral scan function. Dose measurements were performed using a Rando phantom and two types of thermoluminescent dosimeters. The effective doses recommended by the International Commission on Radiological Protection in 1990 were evaluated using the tissue or organ doses determined with the phantom measurement. The resultant effective dose per CT examination ranged from 4.6 to 10.8 mSv for chest examination and from 6.7 to 13.3 mSv for upper abdominal examination. It should be noted that the effective dose from CT examination will be increased by increasing in the frequency of CT examinations and technical development of CT scanners. 相似文献
30.
Tadao Tanabe Yuichi Kozawa Ken Suto Jun-ichi Nishizawa Ytaka Oyama 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(6):881-892
Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions. 相似文献