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101.
Takashi Fujimoto Kenzo Miyazaki Kuniya Fukuda 《Journal of Quantitative Spectroscopy & Radiative Transfer》1974,14(5):377-384
The hook method has been applied to the positive-column discharge plasma of helium and the population density of the lowest-lying excited levels, 21,3S and 21,3P, was measured. The results are compared with data obtained by use of the line absorption method, and discrepancies between these data are discussed. The result is also compared with a calculation based on application of the collisional-radiative model. 相似文献
102.
Radiochromium uptake from surrounding by HeLa cells was examined, the results were as follows: 1) The chromium uptake by the cells after a certain period of incubation in Ca-Mg free phosphate buffered solution (PBS) with radiosodiumchromate (Na251CrO4) was higher than that in serum free Eagle's minimum essential medium with the same concentration of the radiochromate. 2) When the various amount of L-ascorbic acid was added to the above rabiochromate containing PBS, the chromium uptake by the cells decreased with dependence on the concentration of the acid in the surrounding medium. However, when sodiumthiosulfate was added to the medium, no remarkable effect was found. 3) When cells were incubated in the radiochromic chloride(51CrCl3)containing medium with 6.5 microgram/ml of sodium oxalate, sodium acetate or sodium nitrate, the chromium uptake by the cells increased in comparison with the control. Above results suggested that the chromium uptake by the HeLa cells from surrounding medium was affected by several chemicals and the uptake or binding capacity of chromium was closely related to the reported cytotoxicity of the chromium compounds. 相似文献
103.
104.
Peribysins A-D, potent cell-adhesion inhibitors from a sea hare-derived culture of Periconia species
Yamada T Iritani M Minoura K Kawai K Numata A 《Organic & biomolecular chemistry》2004,2(14):2131-2135
Peribysins A-D 1-4, including a new type of furanofuran, have been isolated from a strain of Periconia byssoides originally separated from the sea hare Aplysia kurodai, and their relative stereostructures have been elucidated on the basis of NMR spectral analyses. All these metabolites potently inhibited the adhesion of human-leukemia HL-60 cells to HUVEC. The activity of compound 4, exhibiting the most potent inhibitory activity, was 380 times as potent as herbimycin A (standard). 相似文献
105.
Hiraoka K Katsuragawa J Sugiyama T Kojima T Yamabe S 《Journal of the American Society for Mass Spectrometry》2001,12(2):144-149
Gas-phase clustering reactions of halide ions (X- = F-, Cl-, Br-, and I-) with ethylene (C2H4) and propylene (C3H6) were studied with a pulsed electron beam mass spectrometer. Bonding energies of all cluster ions were found to be less than 10 kcal/mol, i.e., no anion-initiated polymerization of C2H4 and C3H6 took place. For the cluster F-(C2H4)n, a small gap in the binding energy is observed between n = 4 and 5 suggesting that the first shell is completed with n = 4. For larger halide ions, the bond energies for the clusters X-(C2H4)n were found to be nearly n independent. For Cl-(C3H6)n a steep decrease in binding energies was observed between n = 2 and 3 and n = 3 and 4. The structure of the cluster ions was investigated by ab initio calculations. X-(C2H4)n complexes were calculated to have hydrogen-bond geometries regardless of the identity of the halide ions, and bidentate (chelate) type geometries of X-(C3H6)1 were found. 相似文献
106.
107.
Dr. Jun Nakamura Hidenori Yamashiro Hiroto Miya Dr. Kenzo Nishiguchi Dr. Hideki Maki Prof. Dr. Hirokazu Arimoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(36):12104-12112
Vancomycin‐resistant Staphylococcus aureus (S. aureus) (VRSA) uses depsipeptide‐containing modified cell‐wall precursors for the biosynthesis of peptidoglycan. Transglycosylase is responsible for the polymerization of the peptidoglycan, and the penicillin‐binding protein 2 (PBP2) plays a major role in the polymerization among several transglycosylases of wild‐type S. aureus. However, it is unclear whether VRSA processes the depsipeptide‐containing peptidoglycan precursor by using PBP2. Here, we describe the total synthesis of depsi‐lipid I, a cell‐wall precursor of VRSA. By using this chemistry, we prepared a depsi‐lipid II analogue as substrate for a cell‐free transglycosylation system. The reconstituted system revealed that the PBP2 of S. aureus is able to process a depsi‐lipid II intermediate as efficiently as its normal substrate. Moreover, the system was successfully used to demonstrate the difference in the mode of action of the two antibiotics moenomycin and vancomycin. 相似文献
108.
Lee Chuin Chen Md. Matiur Rahman Kenzo Hiraoka 《Journal of mass spectrometry : JMS》2013,48(3):392-398
Super‐atmospheric pressure chemical ionization (APCI) mass spectrometry was performed using a commercial mass spectrometer by pressurizing the ion source with compressed air up to 7 atm. Similar to typical APCI source, reactant ions in the experiment were generated with corona discharge using a needle electrode. Although a higher needle potential was necessary to initiate the corona discharge, discharge current and detected ion signal were stable at all tested pressures. A Roots booster pump with variable pumping speed was installed between the evacuation port of the mass spectrometer and the original rough pumps to maintain a same pressure in the first pumping stage of the mass spectrometer regardless of ion source pressure. Measurement of gaseous methamphetamine and research department explosive showed an increase in ion intensity with the ion source pressure until an optimum pressure at around 4–5 atm. Beyond 5 atm, the ion intensity decreased with further increase of pressure, likely due to greater ion losses inside the ion transport capillary. For benzene, it was found that besides molecular ion and protonated species, ion due to [M + 2H]+ which was not so common in APCI, was also observed with high ion abundance under super‐atmospheric pressure condition. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
109.
Kakue T Yonesaka R Tahara T Awatsuji Y Nishio K Ura S Kubota T Matoba O 《Optics letters》2011,36(21):4131-4133
Parallel phase-shifting digital holography can obtain three-dimensional information of a dynamically moving object with high accuracy by using space-division multiplexing of multiple holograms required for phase-shifting interferometry. We demonstrated high-speed parallel phase-shifting digital holography and obtained images of the phase variation of air caused by a compressed gas flow sprayed from a nozzle. In particular, we found the interesting phenomenon of periodic phase distributions. Reconstructed images were obtained at frame rates of 20,000 and 180,000 frames per second. 相似文献
110.
Ahsan Habib Satoshi Ninomiya Lee Chuin Chen Dilshadbek T. Usmanov Kenzo Hiraoka 《Journal of the American Society for Mass Spectrometry》2014,25(7):1177-1180
In this work, desorption of nonvolatile analytes induced by friction was studied. The nonvolatile compounds deposited on the perfluoroalkoxy substrate were gently touched by an ultrasonic cutter oscillating with a frequency of 40 kHz. The desorbed molecules were ionized by a dielectric barrier discharge (DBD) ion source. Efficient desorption of samples such as drugs, pharmaceuticals, amino acids, and explosives was observed. The limits of detection for these compounds were about 1 ng. Many compounds were detected in their protonated forms without undergoing significant fragmentation. When the DBD was off, no ions for the neutral samples could be detected, meaning that only desorption along with little ionization took place by the present technique. Figure
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