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151.
Absolute cross sections for the quenching of Cd(3P1) and Cd(3P0) by acetylene, ethylene, propene, cis-2-butene and four fluoroethylenes have been determined by a phase-shift method. It was found that acetylene and olefins quench the triplet cadmium at almost gas-kinetic encounter, while the quenching rates for fluoroethylenes were found to decrease with the increase in the number of substituted fluorine atoms. It was also observed that these molecules do not cause intramultiplet mixing between Cd(3P1) and Cd(3P0). The causes of the decrease of the reactivities of fluoroethylenes are discussed. 相似文献
152.
Dyal A Loos K Noto M Chang SW Spagnoli C Shafi KV Ulman A Cowman M Gross RA 《Journal of the American Chemical Society》2003,125(7):1684-1685
We report the stability and enzymatic activity of Candida rugosa Lipase (E.C.3.1.1.3) immobilized on gamma-Fe2O3 magnetic nanoparticles. The immobilization strategies were either reacting the enzyme amine group with a nanoparticle surface acetyl, or amine groups. In the former, the enzyme was attached through a C=N bond, while in the latter it was connected using glutaraldehyde. AFM images show an average particle size of 20 +/- 10 nm after deconvolution. The enzymatic activity of the immobilized lipase was determined by following the ester cleavage of p-nitrophenol butyrate. The covalently immobilized enzyme was stabile and reactive over 30 days. 相似文献
153.
Saito Kazuya Ikeda Mayumi Sorai Michio 《Journal of Thermal Analysis and Calorimetry》2002,70(2):345-352
Meaning of the alkyl chain-length dependence of transition entropy in liquid crystal is discussed and clarified in a long-chain
region. A method to deduce contributions of the alkyl chain and the molecular core is proposed. Application of the method
suggests that, in most smectic A (SmA) - nematic (N) phase transitions, not only a molecular core (modeled by a hard-rod)
but also a (terminal) alkyl chain is disordered upon the SmA→N transition.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
154.
Kiyose K Hanaoka K Oushiki D Nakamura T Kajimura M Suematsu M Nishimatsu H Yamane T Terai T Hirata Y Nagano T 《Journal of the American Chemical Society》2010,132(45):15846-15848
Based on the findings that the azo functional group has excellent properties as the hypoxia-sensor moiety, we developed hypoxia-sensitive near-infrared fluorescent probes in which a large fluorescence increase is triggered by the cleavage of an azo bond. The probes were used for fluorescence imaging of hypoxic cells and real-time monitoring of ischemia in the liver and kidney of live mice. 相似文献
155.
Akahoshi N Ishizaki I Naya M Maekawa T Yamazoe S Horiuchi T Kajimura M Ohashi Y Suematsu M Ishii I 《Analytical and bioanalytical chemistry》2012,402(5):1859-1864
In vivo imaging of reactive small molecule metabolites with high spatial resolution and specificity could give clues to understanding
pathophysiology of various diseases. We herein applied time of flight-secondary ion mass spectrometry (TOF-SIMS) to newly
developed silver-deposited plates that were stamped on mouse tissues, and succeeded in visualization of halide (Cl−, Br−, and I−) and pseudohalide thiocyanate (SCN−) anions, a class of substrates for neutrophils/eosinophil peroxidases to produce hypohalous acids (HOX/OX− mixture; X: (pseudo)halides), as well as hydrogen sulfide (H2S). Forty-micrometer frozen mouse kidney sections on cover glasses were attached to 37 °C preheated silver-deposited plates
and incubated at −10 °C for 1 h. After sputter cleaning to remove surface contaminants, the plates were analyzed by TOF-SIMS
to identify distribution of Br−, AgBr2−, I−, AgI2−, SCN−, as well as S2− and AgS− as products of tissue-derived H2S. Br−, AgBr2−, I−, and SCN− anions were mainly distributed in core regions including the inner medulla and inner stripe of the outer medulla (except
for I−), rather than outer regions such as the cortex and outer stripe of the outer medulla. AgI2− anion was spread over the whole kidney, although its levels were relatively low. In contrast, S2− and AgS− anions were mainly present in the outer regions. To our knowledge, this is the first imaging study to reveal the distribution
of (pseudo)halides and H2S in animal tissue sections. 相似文献
156.
Asakawa Y Ludwiczuk A Harinantenaina L Toyota M Nishiki M Bardon A Nii K 《Natural product communications》2012,7(6):685-692
The liverwort, Porella vernicosa complex produces a very hot tasting polygodial, a drimane-type sesquiterpene dialdehyde. The same compound has been isolated from two ferns, Thelypteris hispidula and Blechnum fluviatile, as well as from the higher plants Polygonum hydropiper, P. hydropiper f. purpurascens (Polygonaceae), Cinnamosma, Caspicodendron, Canella and Warburgia species (Canellaceae), and Pseudowintera colorata, Tasmannia lanceolata, Drimys and Zygogynum species (Winteraceae). In addition, the liverworts and higher plants which elaborate polygodial and its related pungent drimane dials contain a small amount of alpha-tocopherol, gamma-tocopherol or delta-tocotrienol. The present paper gives the results of a comparative study on the drimane-type sesquiterpenoids in some liverworts, ferns and higher plants, and the role of tocopherols in these plant groups. 相似文献
157.
K. Yokoi Maki Yakushiji Mayumi Hatanaka Koji Kubono Tsutomu Koide 《Fresenius' Journal of Analytical Chemistry》1999,365(4):364-367
A high output low-pressure mercury lamp, 400 W L-Hg, was successfully used for the photolytic decomposition of dissolved
oganic compounds as the pretreatment for the determination of trace metal ion in aqueous solution by stripping voltammetry.
Various amino acids, showing interferences on voltammetric determination of metal ions, can be removed quite easily by intensive
UV irradiation at room temperature. Effect of pH, concentration of electrolyte and dissolved oxygen on the efficiency of photolysis
are also described. This method uses no additional chemicals such as acids or oxidants and can be carried out in closed clean
conditions.
Received: 1 February 1999 / Revised: 19 April 1999 / Accepted: 5 May 1999 相似文献
158.
In this study, a new synthetic approach to 4,5-branched Kdo trisaccharides based on the common acceptor Kdo(α2-4)Kdo was developed. The synthesis of three types of 4,5-branched trisaccharides, Hep(α1-5)[Kdo(α2-4)]Kdo, Man(α1-5)[Kdo(α2-4)]Kdo, and GalNAc(α1-5)[Kdo(α2-4)]Kdo, was achieved in good yield and high α-selectivity. 相似文献
159.
Mayumi Matsushita-Morita Hiroyuki Nakagawa Sawaki Tada Junichiro Marui Ryota Hattori Satoshi Suzuki Youhei Yamagata Hitoshi Amano Hiroki Ishida Michio Takeuchi Ken-Ichi Kusumoto 《Applied biochemistry and biotechnology》2013,171(1):145-164
β-Aminopeptidases exhibit both hydrolytic and aminolytic (peptide bond formation) activities and have only been reported in bacteria. We identified a gene encoding the β-aminopeptidase homolog from a genome database of the filamentous fungus Aspergillus oryzae. The gene was overexpressed in A. oryzae, and the resulting recombinant enzyme was purified. Apart from bacterial homologs [β-Ala-para-nitroanilide (pNA)], the enzyme preferred d-Leu-pNA and d-Phe-pNA as substrates. Therefore, we designated this gene as d-stereoselective aminopeptidase A (damA). The purified recombinant DamA was estimated to be a hexamer and was composed of two subunits with molecular masses of 29.5 and 11.5 kDa, respectively. Optimal hydrolytic activity of DamA toward d-Leu-pNA was observed at 50 °C and pH 8.0. The enzyme was stable up to 60 °C and from pH 4.0–11.0. DamA also exhibited aminolytic activity, producing d-Leu-d-Leu-NH2 from d-Leu-NH2 as a substrate. In the presence of 3.0 M NaCl, the amount of pNA liberated from d-Leu-pNA by DamA was 3.1-fold higher than that in the absence of NaCl. Thus, DamA is a halophilic enzyme. The enzyme was utilized to synthesize several hetero-dipeptides containing a d-amino acid at the N-terminus as well as physiologically active peptides. 相似文献
160.