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171.
172.
Joseph I. Degraw Hiroaki Tagawa Pamela H. Christie John A. Lawson Edward G. Brown Roy L. Kisliuk Yvette Gaumont 《Journal of heterocyclic chemistry》1986,23(1):1-4
The synthesis of 5,10-dideazaaminopterin by two independent routes is described. Condensation of the piperidine enamine of 4-p-carbomethoxyphenylbutyraldehyde ( 4 ) with ethoxymethylenemalononitrile followed by treatment of the resultant arylethylenaminomalononitrile ( 5 ) with methanolic ammonia produced 2-amino-3-cyano-5-p-carbomethoxyphenethylpyridine ( 6 ). Cyclization of the aminocyanopyridine with guanidine afforded 4-amino-4-deoxy-5,10-dideazapteroic acid ( 8 ). Coupling of the pteroate intermediate with glutamate yielded the target 5,10-dideazaaminopterin ( 10 ). Alternatively, reduction of 2,4-diamino-6-formyl-5-deazapteridine ( 11 ) with sodium borohydride gave the 6-hydroxymethyl compound 12 . Conversion to the bromide was followed by alkylation of dimethyl homoterephthalate to afford methyl 4-amino-4-deoxy-10-carbomethoxy-5,10-dideazapteroate ( 14 ). Decarboxylation with ester cleavage (sodium cyanide in dimethyl sulfoxide at 180°) also gave the diaminopteroic acid ( 8 ). 5,10-dideazaaminopterin ( 10 ) was an effective growth inhibitorof folate dependent bacteria, S. faecium and L. casei. 相似文献
173.
We point out the possibility that reactor measurement of θ13, when combined with high-statistics νe appearance accelerator experiments, can detect leptonic CP violation. Our proposal is based on a careful statistical analysis under reasonable assumptions on systematic errors, assuming 2 years running of the neutrino mode J-PARC → Hyper-Kamiokande experiment and a few years running of a reactor experiment with 100 t detectors at the Kashiwazaki–Kariwa nuclear power plant. We show that the method can be arranged to be insensitive to the intrinsic parameter degeneracy but is affected by the one due to unknown sign of Δm231. 相似文献
174.
Michihito Ueda Masahiro Ueda Hiroaki Takagi Masayuki J. Sato Toshio Yanagida Ichiro Yamashita Kentaro Setsune 《Physica A》2008,387(16-17):4475-4481
“End of Moore’s Law” has recently become a topic. Keeping the signal-to-noise ratio (SNR) at the same level in the future will surely increase the energy density of smaller-sized transistors. Lowering the operating voltage will prevent this, but the SNR would inevitably degrade. Meanwhile, biological systems such as cells and brains possess robustness against noise in their information processing in spite of the strong influence of stochastic thermal noise. Inspired by the information processing of organisms, we propose a stochastic computing model to acquire information from noisy signals. Our model is based on vector matching, in which the similarities between the input vector carrying external noisy signals and the reference vectors prepared in advance as memorized templates are evaluated in a stochastic manner. This model exhibited robustness against the noise strength and its performance was improved by addition of noise with an appropriate strength, which is similar to a phenomenon observed in stochastic resonance. Because the stochastic vector matching we propose here has robustness against noise, it is a candidate for noisy information processing that is driven by stochastically-operating devices with low energy consumption in future. Moreover, the stochastic vector matching may be applied to memory-based information processing like that of the brain. 相似文献
175.
176.
Hiroaki Minamisawa Ryoko Okunugi Mayumi Minamisawa Satoshi Tanaka Kazunori Saitoh Nobumasa Arai Masami Shibukawa 《Analytical sciences》2006,22(5):709-713
The solid-phase extraction (SPE) method for the preconcentration of trace amounts of cadmium using synthetic zeolite A-4 and its determination by graphite furnace atomic absorption spectrometry (GFAAS) was investigated. The preconcentration conditions, such as the optimum pH range of the sample solution for the adsorption of cadmium and the kind of acid solution for dissolving the cadmium-adsorbed synthetic zeolite A-4, as well as the measurement conditions for the determination of cadmium by GFAAS, e.g., the ashing and atomizing temperature, were investigated. Quantitative recovery of cadmium onto zeolite A-4 from the sample solution over the pH range 2.0 - 9.0 was achieved by the batch method. After the solid-phase (cadmium-adsorbed zeolite A-4) was separated from the sample solution by a membrane filter, it was dissolved in 2.0 cm(3) of 2.0 mol dm(-3) nitric acid. An aliquot of the resulting solution was injected into the graphite furnace. In GFAAS measurements an alternate gas (Ar, 90%; O(2), 10%) was used as a sheath gas, and the ashing temperature and atomizing temperature were 400 degrees C and 1600 degrees C, respectively. The detection limit (3 sigma) for cadmium was 0.002 microg dm(-3). The relative standard deviation at 0.010 microg dm(-3) was 3.5 - 4.5% (n = 5). The proposed method has been successfully applied to the analysis of trace cadmium in environmental water samples. 相似文献
177.
Daisuke Adachi Kohei Takei Toshihiko Toyama Hiroaki Okamoto 《Applied Surface Science》2007,254(1):299-302
Effects of ZnS:Mn/AlN multilayer structure on luminescent properties of nanostructured (NS) thin-film electroluminescent (TFEL) device of which emission layer is a multilayer composed with ZnS:Mn layers and 0.7-nm-thick AlN interlayers were studied. The bandgap widening and the increased PL efficiency of Mn2+ 3d-3d transitions with a decrease in the ZnS:Mn single-layer thickness down to 5 nm were observed, which is ascribed to quantum confinement effects. Meanwhile, the multilayer with 2-nm-thick ZnS:Mn single-layers shows a drop of PL efficiency, indicating the presence of defective region just on AlN. The tendency of the luminous efficiency of the NS-TFEL device against the ZnS:Mn single-layer thickness is similar to the tendency found in the PL efficiency, indicating the importance of the ZnS:Mn/AlN interface for the device performance. 相似文献
178.
Hiroaki Aikawa Tero Kilpeläinen Nageswari Shanmugalingam Xiao Zhong 《Potential Analysis》2007,26(3):281-301
We establish a scale-invariant version of the boundary Harnack principle for p-harmonic functions in Euclidean C
1,1-domains and obtain estimates for the decay rates of positive p-harmonic functions vanishing on a segment of the boundary in terms of the distance to the boundary. We use these estimates
to study the behavior of conformal Martin kernel functions and positive p-superharmonic functions near the boundary of the domain.
H. A. was partially supported by Grant-in-Aid for (B) (2) (No. 15340046) Japan Society for the Promotion of Science. N. S.
was partially supported by NSF grant DMS-0355027. X. Z. was partially supported by the Taft foundation. 相似文献
179.
Atsuko Ito Keiko Iwai Chiyuki Oyama Setsu Morimoto Hiroaki Kato 《Hyperfine Interactions》1992,71(1-4):1371-1374
Magnetization and Mössbauer measurements have been made on a diluted antiferromagnets FexMg1?xTiO3 with x=0.2, 0.3 and 0.7. It has been demonstrated that this system exhibits a spin glass or a reentrant spin glass like behavior in the samples with x around the percolation concenrration xc≈0.25. It has been shown that various sizes of magnetic clusters are formed well above the transition temperatures determined by the magnetization measurements in the samples with x near xc. The behavior of Fe0.2Mg0.8TiO3 is discussed as a typical cluster glass. 相似文献
180.
The alignment correlation term in the β-decay angular distribution from purely nuclear spin aligned 20Na has been measured for the first time. The final objective is to test the G parity symmetry, one of the fundamental symmetry in the weak nucleon current. For artificial creation of the alignment, the
knowledge of the hyperfine interaction of 20Na implanted in a single-crystal ZnO was utilized.
*Research Abroad, Japan Society for the Promotion of Science 相似文献