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21.
The high-pressure effects on lithium ion conduction in LiBH4 have been investigated. The high-pressure ac-impedance measurement was performed by using a cubic anvil-type apparatus under 2 to 6 GPa at various temperatures. For the hexagonal structure (Phase I), the activation volume for lithium ion conduction was found to be around 3 cm3/mol (≈ 0.09Vm, where Vm means its molar volume). This activation volume is almost comparable to that for other fast-ion conductors such as NASICONs. The lithium ion conductivities of orthorhombic (Phase III) and cubic (Phase V) structures were also measured. Regardless of crystal structures, the activation energies of Phases I, III, and V were almost identical at around 50 to 60 kJ/mol; on the other hand, the pre-exponential terms of Phases III and V were smaller than those of Phase I by one to two orders of magnitude. 相似文献
22.
S. Takamura 《辐射效应与固体损伤》2013,168(4):115-118
Temperature dependence of yield stress was studied on Mo single crystals of two orientations after neutron irradiation at low temperature. After the low temperature irradiation, the yield stresses decreased. The isochronal annealing measurements of yield stress were also performed. The yield stresses after low temperature irradiation recovered with increasing of annealing temperature. 相似文献
23.
Hiroko Nakagawa Kumiko Ohtsuka Katsuhito Sugahara Chika Kobayashi Yuichi Masuoka Koh-ichi Yamada Masami Kawase 《Tetrahedron: Asymmetry》2010,21(6):659-664
Helical [5]thiaheterohelicene 5HM, which rapidly interconverts between P and M enantiomers in solution, was connected to helical l-phenylalanine oligomers with an ester linkage to give peptidehelicenes (5Fn, where n: number of bonded phenylalanines). The characteristics of 5F4 and 5F5 with two types of helixes in a molecule were investigated, particularly in comparison with those of 5F1–5F3 with an incomplete coil of a peptide moiety. l-Phenylalanine peptide chains induced a shift in the equilibrium between the P and M helixes of 5HM toward the P side for all the 5Fns examined. The enantiomeric excess (ee) of the P form increased with a decrease in temperature, together with an elongation of the peptide chains. 5F4 and 5F5 in hot solutions of some solvents formed a gel at room temperature, whereas 5F1–5F3 showed no such behavior. In this gel, the stable helical form of the 5HM moiety in 5F4 and 5F5 was observed to be the M form in contrast to that in their solutions. 相似文献
24.
Isao Kadota Takayuki Kishi Yuka Fujisawa Yuji Yamagami Hiroyoshi Takamura 《Tetrahedron letters》2010,51(30):3960-5853
A convenient method for the stereoselective construction of angular methyl group of fuzed cyclic ethers is described. Reactions of mixed thioacetals with Me2Zn/Zn(OTf)2 afforded the corresponding methylated products in good yields. Various protective groups such as MOM ether, benzylidene acetal, TBS ether, and pivaloyl group were stable under the reaction conditions. 相似文献
25.
In this work, a sensitive label-free impedimetric hCG-immunosensor was constructed by using a commercial screen-printing carbon ink electrode (namely disposable electrochemical printed chip) as the basis. The carbon ink electrode of DEP chip is modified first by deposition of polypyrrole-pyrole-2-carboxylic acid copolymer and thence hCG antibody immobilization via the COOH groups of pyrrole-2-carboxylic acid, which can serve as a linker for covalent biomolecular immobilization. The experimental results exposed that the designed immunosensor is more sensitive than other previously reported immunosensors, in the case of detection limit and linear range for antigen detection. With optimal fabrication parameters, the detection limit for α-hCG was 2.3 pg/mL in 10 mM phosphate buffer saline (PBS) solution containing 1% bovine serum albumine (BSA). Moreover, the use of inexpensive DEP chip as a basis for these immunosensors will allow for simple instrumentation, disposable and portable at low cost. This work also demonstrates a new approach to develop a sensitive and label-free impedimetric immunosensor based on screen-printed electrode for applications in clinical diagnosis. 相似文献
26.
Kumazawa T Hasegawa C Uchigasaki S Lee XP Suzuki O Sato K 《Journal of chromatography. A》2011,1218(18):2521-2527
Solid-phase extraction (SPE) using micropipette tips is a useful technique to prepare samples prior to mass spectrometry. However, most commercial SPE tips have loading capacities that are insufficient for quantitative determination. In this paper, we describe a rapid method for quantitative microanalysis of five phenothiazine derivatives, chlorpromazine, levomepromazine, promazine, promethazine and trimeprazine, using a recently introduced C(18) monolithic silica SPE tip, the MonoTip C(18), for extraction from human plasma. The drugs could be extracted within 5 min from 0.1-mL plasma samples, eluted with methanol, and the eluate injected directly into a gas chromatograph prior to mass spectrometry analysis. Only 0.7 mL of solvent was required for each step of the extraction process. The recoveries of the five phenothiazines spiked into plasma were 91-95% and the limits of quantification for each drug were between 0.25 and 2.0 ng/0.1 mL. The maximum intra- and inter-day coefficient of variation was 11%. The validated method was successfully used to quantify the plasma concentration of levemepromazine in a human subject after oral administration of the drug. This new method is expected to have wide applications as a pretreatment for the rapid, quantitative determination of drug concentrations in plasma samples. 相似文献
27.
The HIJKLM ring system of ciguatoxin CTX3C was synthesized in a convergent manner. The key steps were a conjugate addition/alkylation sequence, spiroacetalization, intramolecular allylation, ring-closing metathesis, and hydrogenation to form the 36-α-methyl substituent. 相似文献
28.
Yokoe H Mitsuhashi C Matsuoka Y Yoshimura T Yoshida M Shishido K 《Journal of the American Chemical Society》2011,133(23):8854-8857
Enantiocontrolled total syntheses of the breviones A, B, and C have been accomplished using a highly diastereoselective oxidative coupling of an α-pyrone with a tricyclic diene prepared from an optically pure Wieland-Miescher ketone derivative through the 7-endo-trig mode of acyl radical cyclization. 相似文献
29.
Y. Takamura S. Nakagawa K. Suzuki K. Takahashi H. Asano G. Sugihara M. Ueno 《Colloids and surfaces. B, Biointerfaces》1996,7(5-6):239-247
The behavior of sodium glycochenodeoxycholate (NaGCDC) and sodium glycoursodeoxycholate (NaGUDC) in binary mixed micelles consisting of bile salt and octaoxyethylene glycol mono n-decyl ether (C10E8) has been studied on the basis of micellar compositions, polarities of the interior of intramicelles, mean aggregation numbers and 1H NMR measurements. Micellar compositions for both NaGCDC---C10E8 and NaGUDC---C10E8 systems showed a tendency to change from C10E8-rich micelles to bile-salt-rich micelles with an increase on the mole fraction of bile salts from the results of both theoretical calculations using the critical micelle concentration and the micellar polarity. The microenvironment of intramicelles for the NaGCDC---C10E8 system was found to be more hydrophobic than that for the NaGUDC---C10E8 system. Mean aggregation numbers of mixed micelles for both systems decreased abruptly with an increase in the mole fraction of bile salts in the range of low mole fraction, but those for NaGCDC were larger than those for NaGUDC. Furthermore, from the results of 1H NMR measurements, the motions of the methyl group protons in the 18 position of the molecular structure of NaGCDC were slightly restricted with an increase in the mole fraction of NaGCDC. In contrast, the methyl group protons in the 18 and 19 positions of the molecular structure of NaGUDC became freer with an increase in the mole fraction of NaGUDC. 相似文献
30.
It is shown that in a certain range of the h. f. power, the h. f. (T-D resonances) and the l. f. (ion sound wave and its harmonics) oscillations are parametrically excited in a certain region of the hysteresis loop. 相似文献