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81.
82.
A non-integrable system has an irregular spectrum for stationary bound energy levels. It is shown that the irregular sequence of level spacings gives an unambiguous representation of chaos in quantum systems. 相似文献
83.
Kiriya D Chang HC Kamata A Kitagawa S 《Dalton transactions (Cambridge, England : 2003)》2006,(11):1377-1382
A novel series of valence tautomeric (VT) complexes, [Co(Cnbpy)(3,5-DTBQ)2] (Cnbpy = 4,4'-dialkyl-2,2'-bipyridine (alkyl = (C(n)H(2n+1)) where n = 0 (CoC0bpy), 1 (CoC1bpy), 5 (CoC5bpy), 9 (CoC9bpy) and 13 (CoC13bpy); 3,5-DTBQ = 3,5-di-tert-butylsemiquinonate or catecholate), including two previously reported complexes (CoC0bpy and CoC1bpy), were systematically prepared and their properties examined. Introduction of alkyl groups into VT chromophores leads to unexpected variations in the VT process, depending on the lengths of the alkyl chains. An even more interesting observation is that significant polytypic phase transitions with crystallographic symmetry changes accompanying the abrupt VT conversion are induced for the first time in CoC9bpy and CoC13bpy. 相似文献
84.
Using a straightforward chemo-enzymatic procedure, 1-beta-O-acyl glucuronides of three non-steroidal anti-inflammatory drugs, diclofenac (DF) 5, mefenamic acid (MF) 6 and (S)-naproxen (NP) 7, were prepared. Caesium salts of these carboxylic acid drugs reacted with commercially available methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-alpha-D-glucopyranuronate 4 to give exclusively the corresponding 1-beta-O-acyl glucuronides 8-10 in moderate yields. The protecting acetyl (for -OH group) and methyl ester (for -CO2H group) groups of each sugar moiety were easily removed to provide the corresponding free 1-beta-O-acyl glucuronides 1-3 in high yields. Deprotection was achieved through effective enzyme-catalysed chemo-selective hydrolyses of the acetyl groups using lipase AS Amano (LAS), and of the methyl ester group using esterase from porcine liver (PLE). 相似文献
85.
Inagaki K Takatsu A Nakama A Eyama S Yarita T Okamoto K Chiba K 《Analytical and bioanalytical chemistry》2006,385(1):67-75
A method is described for determination of selenium in sediment by isotope-dilution inductively coupled plasma mass spectrometry
with an octapole reaction cell (ID–ICP–ORCMS). Sediment samples were digested with HNO3, HClO4, and HF, and the digestion included an elaborate evaporation process to remove bromine from the digested solution. Simple
strong cation-exchange disk filtration was used to remove rare earth elements (REE) from the digested solution, because REE2+ seriously interfere with Se isotopes (i.e. 156Gd2+ with 78Se+, 160Gd2+ with 80Se+). Addition of acetic acid to the filtrate was examined to improve the sensitivity of ICP–ORCMS measurement of Se+ by means of a carbon-enhancement effect. The interfering for selenium isotopes were almost eliminated by use of H2 as reaction gas. Interference from BrH+ formed in the reaction cell was negligible because the Br was removed in the evaporation process. Approximately 99.5% of
REE were removed by cation-exchange disk filtration yet more than 99% of Se remained in the filtrate solution. The intensity
for Se+ was enhanced approximately fourfold by addition of 5% (v/v) of acetic acid whereas that for was barely enhanced. Measured 80Se/78Se ratios in unspiked digested solutions of the sample were in good agreement with that for an Se standard solution. The analytical
results for Se in the certified reference materials MESS-3 and PACS-1 were in good agreement with their certified values,
with small uncertainties.
相似文献
86.
Nomura A Uyeda TQ Yumoto N Tatsu Y 《Chemical communications (Cambridge, England)》2006,(34):3588-3590
To design a nanoscale biodevice that can be controlled by an external stimulus, we have introduced photochemical switching peptides derived from the kinesin C-terminus domain into the kinesin-microtubule in vitro motility system. 相似文献
87.
You Takahashi Akiko Fukuda Emiko Ishiwata Yoshimasa Nakamura 《Applicable analysis》2013,92(3):586-594
The integrable discrete hungry Lotka–Volterra (dhLV) system is easily transformed to the qd-type dhLV system, which resembles the recursion formula of the qd algorithm for computing matrix eigenvalues. Some of the qd-type dhLV variables play a role for assisting the time evolution of the others. This property does not appear in the original dhLV system. In this article, we first show the existence of a centre manifold for the qd-type dhLV system. With the help of the centre manifold theory, we next investigate the local convergence of the qd-type dhLV system, and then clarify the monotonicity related to the qd-type dhLV variables at the final phase of the convergence. 相似文献
88.
Hisahiro Nakayama Jiro Kasahara Akiko Matsuo Ikkoh Funaki 《Proceedings of the Combustion Institute》2013,34(2):1939-1947
The propagation of curved detonation waves of gaseous explosives stabilized in rectangular-cross-section curved channels is investigated. Three types of stoichiometric test gases, C2H4 + 3O2, 2H2 + O2, and 2C2H2 + 5O2 + 7Ar, are evaluated. The ratio of the inner radius of the curved channel (ri) to the normal detonation cell width (λ) is an important factor in stabilizing curved detonation waves. The lower boundary of stabilization is around ri/λ = 23, regardless of the test gas. The stabilized curved detonation waves eventually attain a specific curved shape as they propagate through the curved channels. The specific curved shapes of stabilized curved detonation waves are approximately formulated, and the normal detonation velocity (Dn)?curvature (κ) relations are evaluated. The Dn nondimensionalized by the Chapman–Jouguet (CJ) detonation velocity (DCJ) is a function of the κ nondimensionalized by λ. The Dn/DCJ?λκ relation does not depend on the type of test gas. The propagation behavior of the stabilized curved detonation waves is controlled by the Dn/DCJ?λκ relation. Due to this propagation characteristic, the fully-developed, stabilized curved detonation waves propagate through the curved channels while maintaining a specific curved shape with a constant angular velocity. Self-similarity is seen in the front shock shapes of the stabilized curved detonation waves with the same ri/λ, regardless of the curved channel and test gas. 相似文献
89.
Leandro Marcondes-Alves Victor Fattori Sergio M. Borghi Yuri Lourenco-Gonzalez Allan J.C. Bussmann Elisa Y. Hirooka 《Natural product research》2019,33(6):921-924
Acetaminophen (paracetamol) is a widely used analgesic and antipyretic drug that is safe at therapeutic doses. However, acetaminophen overdose can be fatal. Currently, the only treatment available is the N-acetyl cysteine. The diterpene kaurenoic acid (ent-kaur-16-en-19-oic acid, KA) is the major constituent of Sphagneticola trilobata (L.) Pruski. KA presents anti-inflammatory, anti-nociceptive and antioxidant properties. In this study, we evaluated the efficacy of KA in a model of acetaminophen-induced hepatotoxicity. KA increased, in a dose-dependent manner, the survival rate after acetaminophen overdose. KA reduced acetaminophen-induced hepatic necrosis and ALT and AST levels. KA decreased acetaminophen-induced neutrophil and macrophage recruitment, oxidative stress and the production of IL-33, TNF-α and IL-1β, alongside with normalisation of IL-10 levels in the liver. Therefore, KA showed preclinical efficacy in acetaminophen-induced hepatotoxicity and lethality. 相似文献
90.
Prof. Isao Fujii Dr. Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Dr. Takashi Asano Dr. Jun Ishikawa Dr. Daigo Wakana Dr. Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Dr. Junichiro Kanazawa Dr. Hajime Sato Prof. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8542-8548
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark. 相似文献