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21.
In the traditional design of reliability tests for assuring the mean time to failure (MTTF) in Weibull distribution with shape and scale parameters, it has been assumed that the shape parameter in the acceptable and rejectable populations is the same fixed number. For the purpose of expanding applicability of the reliability testing, Hisada and Arizono have developed a reliability sampling scheme for assuring MTTF in the Weibull distribution under the conditions that shape parameters in the both populations do not necessarily coincide, and are specified as interval values, respectively. Then, their reliability test is designed using the complete lifetime data. In general, the reliability testing based on the complete lifetime data requires the long testing time. As a consequence, the testing cost becomes sometimes expensive. In this paper, for the purpose of an economical plan of the reliability test, we consider the sudden death procedure for assuring MTTF in Weibull distribution with variational shape parameter. 相似文献
22.
Ikuo Atsuya Kunihiko Akatsuka Kohji Itoh 《Fresenius' Journal of Analytical Chemistry》1990,337(3):294-298
Summary The selection of standard materials for the establishment of calibration curves is one of the most important problems in the direct analysis of biological samples by GFAAS. Three kinds of standard materials, NBS tomato leaves, coprecipitates with magnesium oxinate and Ni/DMG/PAN were investigated. It was found that it is possible to use both the NBS-SRM and the synthetic reference material prepared by coprecipitation with magnesium oxinate as standard materials for the direct determination of copper in several biological samples issued from NBS and NIES. However, too low results are obtained when the synthetic reference material prepared by coprecipitation with Ni/DMG/PAN is used. In order to clarify this, the effects of nickel and magnesium were examined and the role of magnesium was discussed. 相似文献
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Hiroaki Miyaoka Yoshinori Hara Ikuo Shinohara Takao Kurokawa Yasuji Yamada 《Tetrahedron letters》2005,46(46):7945-7949
Synthesis of the marine eicosanoid agardhilactone has been achieved. The relative and absolute configuration of agardhilactone was successfully determined. 相似文献
25.
Sverine Queyroy Haruki Nakamura Ikuo Fukuda 《Journal of computational chemistry》2009,30(12):1799-1815
This article illustrates practical applications to molecular dynamics simulations of the recently developed numerical integrators [Phys Rev E 2006, 73, 026703] for ordinary differential equations. This method consists of extending any set of ordinary differential equations in order to define a time invariant function, and then use the techniques of divergence‐free solvable decomposition and symmetric composition to obtain volume‐preserving integrators in the extended phase space. Here, we have developed the technique by constructing multiple extended‐variable formalism in order to enhance the handling in actual simulation, and by constituting higher order integrators to obtain further accuracies. Using these integrators, we perform constant temperature molecular dynamics simulations of liquid water, liquid argon and peptide in liquid water droplet. The temperature control is obtained through an extended version of the Nosé‐Hoover equations. Analyzing the effects of the simulation conditions including time step length, initial values, boundary conditions, and equation parameters, we investigate local accuracy, global accuracy, computational cost, and sensitivity along with the sampling validity. According to the results of these simulations, we show that the volume‐preserving integrators developed by the current method are more effective than traditional integrators that lack the volume‐preserving property. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009 相似文献
26.
Kobayashi S Waki T Nakanishi I Matsumoto K Anzai K 《Chemical & pharmaceutical bulletin》2010,58(11):1442-1446
New potent antioxidants conjugating the catechol (=pyrocatechol; pyrCat) group to two N-termini of modified double-stranded tyrosine residues were synthesized and showed radical scavenging activity with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH radical, DPPH˙) as a free radical model, second-order rate constants for the DPPH˙ scavenging reaction, and the results from electron spin resonance (ESR) studies. It was found that the tyrosine (Tyr) residue and pyrCat containing new antioxidants developed in the study have about 3-20 times more potent antioxidative activity than Trolox, pyrCat, and L-ascorbic acid (VC). In order to elucidate the relationship between antioxidant activity and the molecular orbital states, and to design potent antioxidants we present an interesting approach using an absolute hardness (η)-absolute electronegativity (χ) diagram based on chemical hardness. It was shown that quantum chemicals were required to develop potent antioxidants. 相似文献
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Hidekazu Kumano Satoshi Kimura Michiaki Endo Ikuo Suemune Hirotaka Sasakura Satoru Adachi Shunichi Muto Hai Zhi Song Shinichi Hirose Tatsuya Usuki 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):144
Triggered single-photon generation from InAlAs quantum dot (QD) was demonstrated for the first time. Emitted photon energy coincides with high detection efficiency range of Si single-photon detectors, which is highly suitable for free-space communication. Single-QD spectroscopy and crossed photon correlation measurements unambiguously revealed that several emitting lines observed in a single mesa structure originated from the identical QD, and two temporary competing decay processes associated with neutral states and charged states were identified. Presence of the competing process is also inferred from an analysis of steady-state photoluminescence intensities. Formation process of charged exciton in QD is also discussed. 相似文献
29.
Hirotsugu Minami Wanhong Cai Tatsuya Kusumoto Kaiji Nishikawa Qiangbin Zhang Sadanobu Inoue Ikuo Atsuya 《Analytical sciences》2003,19(10):1359-1363
Isotope dilution analysis of the sub-microg l(-1) levels of selenite and selenate in natural water samples by microwave-induced nitrogen plasma mass spectrometry (MIP-MS) was performed. An appropriate amount of a spike solution containing 78Se-selenite and 78Se-selenate was added to the natural water sample to be analyzed. Both analytes in the water were then concentrated simultaneously by passing the sample through a column that was filled with an anionic exchange resin. After the concentration process, all of the selenite and some of the selenate on the resin were eluted by 0.03 M nitric acid. The residual selenate was eluted by 0.13 M nitric acid. The eluted sample solutions were injected into MIP-MS, and isotope dilution analyses were carried out. Selenite and selenate concentrations as low as 0.01 microg l(-1) in the natural water sample were successfully determined by the proposed method. 相似文献
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