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101.
In order to clarify the intermediate valence state found in CeSi2.00, investigations have been made on CeSix (2.00≥×≥1.55). In the composition range 2.00≥×≥1.85, Ce is in the intermediate valence state. For x≤1.80 the system undergoes a sharp magnetic transition. The transient behavior of the magnetic susceptibility, the specific heat and those parameters deduced from these measurements will be discussed. 相似文献
102.
Hidehiko Arai Naohiro Hayakawa Naoyuki Tamura Isamu Kuriyama 《Journal of Polymer Science.Polymer Physics》1977,15(10):1697-1706
The fine texture and molecular motion in rolled (draw ratios λ = 2, λ = 5), cold-drawn (λ = 6), and hot-drawn (λ = 6), linear polyethylene (Sholex 6050) films were studied by small-angle x-ray scattering, wide-line nuclear magnetic resonance (NMR), and dynamic viscoelastic measurements. NMR spectra of the rolled (λ = 5) and cold-drawn samples show a small narrow component at room temperature. For these cold-deformed samples, a gradual decrease in the second moment is observed well below the α relaxation temperature and a new relaxation appears in the same temperature region in the logarithmic decrement versus temperature. This relaxation is absent in the original and hot-drawn samples. It is concluded that the new relaxation arises from molecular motion in intermediate regions where molecular chains are less mobile than in the amorphous state. 相似文献
103.
104.
105.
Garret M. Miyake Hiroki Iida Hai‐Yu Hu Zhenglin Tang Eugene Y.‐X. Chen Eiji Yashima 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5192-5198
Four novel dynamic helical poly(phenylacetylene)s bearing cinchona alkaloids as pendant groups were synthesized starting from the commercially available cinchona alkaloids, cinchonidine, cinchonine, quinine, and quinidine, by the polymerization of the corresponding phenylacetylene monomers with a rhodium catalyst. These polymers exhibited an induced circular dichroism (ICD) in the UV–visible region of the polymer backbones in solution, resulting from the preferred‐handed helical conformation induced by the optically active cinchona alkaloid pendants. In response to the solvent used, their Cotton effect patterns and intensities were significantly changed accompanied by the changes in their absorption spectra probably due to the changes in their helical conformations, such as the inversion of the helical sense or helical pitch of the polymers. When these helical polymers were used as polymeric organocatalysts for the asymmetric conjugated addition and Henry reactions, the optically active products with a modest enantiomeric excess were obtained whose enantioselectivities were comparable to those obtained with the corresponding cinchona alkaloid‐bound monomers as the catalysts. However, we observed a unique enhancement of the enantioselectivity and a reversal of the stereoselectivity for some helical polymers, suggesting the important role of the helical chirality during the asymmetric organocatalysis. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
106.
The effect of stress induced anisotropy on shear band formation 总被引:4,自引:0,他引:4
A. Lizuka C. Yatomi A. Yashima I. Sano H. Ohta 《Archive of Applied Mechanics (Ingenieur Archiv)》1992,62(2):104-114
Summary This paper describes the effect of non-coaxiality arising from material anisotropy on bifurcation phenomena such as shear band formation. The elasto-plastic model originally proposed by Sekiguchi and Ohta [7] is one of the typical models which include anisotropy and it is used to examine the effect of anisotropy on shear band formation. First, we shall extend this elasto-plastic model for infinitesimal strain to a model for finite strain and discuss the mathematical structure of this model. The stress induced anisotropy is found to bring about a vertex-like effect, such as the non-coaxiality between the Cauchy stress tensor and a plastic stretching tensor, into the constitutive relation. Then, we shall examine the effect of this non-coaxiality on bifurcation conditions in relation to the material rigidity which changes with the angle of simple shear. Finally, it will be concluded that this non-coaxiality arising from the anisotropy does not contribute much to triggering instability by localization of the deformations which result in shear band formation, while on the other hand, the non-coaxiality due to the yield vertex effect is rather inclined towards instability by localization of the deformations.
Presented at the workshop on Numerical Methods for Localization and Bifurcation of Granular Bodies, held at the Technical University of Gadansk (Poland), September 25–30, 1989 相似文献
Der Einfluß spannungsinduzierter Anisotropie auf die Scherzonenbildung
Übersicht Beschrieben wird der Einfluß anisotropie-bedingt verschiedener Achsen von Spannung und Deformationsgeschwindigkeit auf Verzweigungsphänomene wie die Scherzonenbildung. Das elastisch-plastische Modell von Sekiguchi und Ohta wird als typisch anisotropes Modell zur Untersuchung des Einflusses der Anisotropie auf die Scherzonenbildung benutzt. Zunächst wird es zu einem Modell für endliche Deformationen erweitert und seine mathematische Struktur erörtert. Es zeigt sich, daß die spannungsinduzierte Anisotropie einen Effekt ähnlich einer Fließortspitze erzeugt wie z. B. verschiedene Achsen von Cauchy-Spannungstensor und plastischem Strecktensor. Danach wird in Zusammenhang mit der Materialsteifigkeit, die vom Winkel der einfachen Scherung abhängt, der Einfluß verschiedener Achsen auf Verzweigungsbedingungen untersucht. Es wird gefolgert, daß anisotropie-bedingt verschiedene Achsen wenig zur Auslösung der Instabilität durch lokalisierte Deformation beitragen, andererseits verschiedene Achsen infolge einer Fließortspitze die Neigung zur lokalisierten Deformation unterstützen.
Presented at the workshop on Numerical Methods for Localization and Bifurcation of Granular Bodies, held at the Technical University of Gadansk (Poland), September 25–30, 1989 相似文献
107.
Yamaoka N Kodama H Izuhara Y Miyata T Meguro K 《Chemical & pharmaceutical bulletin》2011,59(2):215-224
Novel anthranilic acid derivatives having substituted N-acyl side chains were designed and synthesized for evaluation as plasminogen activator inhibitor-1 (PAI-1) inhibitors. Compounds with a 4-diphenylmethyl-1-piperazinyl moiety on the acyl side chains in general exhibited potent in vitro PAI-1 inhibitory activity and good pharmacokinetic profiles after oral administration in rats. Compound 16f (TM5275) was identified as a promising candidate for further pharmacological evaluation. 相似文献
108.
Zirconium vanadates with a novel chemical composition including niobium and yttrium were synthesized by the sol-gel method. An aqueous solution of NH4H2PO4 and NH4V O3 and an ethanol solution of ZrOCl2,NbCl5, and Y Cl3 were prepared. These two solutions were stirred and mixed to prepare precursors of zirconium vanadates at 333 K, following the evaporation of the solvent at 363 K. The precursor gels obtained were heated at 373-973 K in air. A zirconium vanadate phase began to crystallize above 673 K and a single phase of zirconium vanadate was synthesized at 973 K. Although ZrV 2O7 generally had a positive thermal expansion in the temperature range above RT, the degree of positive thermal expansion decreased with the two types of substitution of P for V and a set of Nb and Y for Zr of ZrV 2O7. X-ray diffraction peaks due to a superlattice structure, causing a positive thermal expansion from RT, were not observed in the synthesized (Nb, Y)-substituted zirconium vanadates. 相似文献
109.
Takayoshi Oshima Tom Ichibha Kenji Oqmhula Keisuke Hibino Hiroto Mogi Shunsuke Yamashita Kotaro Fujii Yugo Miseki Kenta Hongo Daling Lu Ryo Maezono Kazuhiro Sayama Masatomo Yashima Koji Kimoto Hideki Kato Masato Kakihana Hiroshi Kageyama Kazuhiko Maeda 《Angewandte Chemie (International ed. in English)》2020,59(24):9736-9743
Undoped layered oxynitrides have not been considered as promising H2‐evolution photocatalysts because of the low chemical stability of oxynitrides in aqueous solution. Here, we demonstrate the synthesis of a new layered perovskite oxynitride, K2LaTa2O6N, as an exceptional example of a water‐tolerant photocatalyst for H2 evolution under visible light. The material underwent in‐situ H+/K+ exchange in aqueous solution while keeping its visible‐light‐absorption capability. Protonated K2LaTa2O6N, modified with an Ir cocatalyst, exhibited excellent catalytic activity toward H2 evolution in the presence of I? as an electron donor and under visible light; the activity was six times higher than Pt/ZrO2/TaON, one of the best‐performing oxynitride photocatalysts for H2 evolution. Overall water splitting was also achieved using the Ir‐loaded, protonated K2LaTa2O6N in combination with Cs‐modified Pt/WO3 as an O2 evolution photocatalyst in the presence of an I3?/I? shuttle redox couple. 相似文献
110.
Riboflavin‐Based Fluorogenic Sensor for Chemo‐ and Enantioselective Detection of Amine Vapors
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Dr. Hiroki Iida Marie Miki Soichiro Iwahana Prof. Dr. Eiji Yashima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(15):4257-4262
A novel turn‐on fluorogenic chiral sensory system has been developed using a protonated riboflavin and riboflavin‐derived cationic polymer as a fluorophore precursor and a specific amine receptor, respectively, which enables the solid‐state chemo‐ and enantioselective fluorogenic visual detection of primary and secondary amine vapors. 相似文献