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1.
Kiyotaka Onitsuka Atsushi Shimizu Fumie Takei Shigetoshi Takahashi 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(1):98-103
A novel multifunctional initiator has been developed by peripheral modification of a Pt-acetylide dendrimer. Pd–Pt μ-ethynediyl
units were introduced to the first-generation dendrimer by a divergent method. The dendritic initiator was applicable to the
living polymerization of aryl isocyanides, producing high molecular weight polymers with a narrow polydispersity index in
quantitative yields. The 31P NMR spectrum of the resulting polymer suggested that all Pd–Pt μ-ethynediyl units in the dendritic molecule actually functioned
as an initiator. 相似文献
2.
A wide range of wireless system developments require knowledge of the distribution of electromagnetic fields from various sources in humans. As experimental assessment is ethically unacceptable, high-resolution numerical dosimetry is needed. The finite-difference time-domain method is the most appropriate due to its simplicity and versatility. Reduction in demands on computational resources can be achieved using subgridding techniques. This paper rigorously introduces frequency dependency to one of the most promising subgridding techniques, Huygens subgridding. The validity of the Huygens surface in lossy media, as well as on the physical interface, is intensively studied. 相似文献
3.
DNA is a typical organic compound with marked differences from other chemicals and biopolymers because DNA can be amplified by the enzyme polymerase. DNA can be, in principle, amplified from a single copy by the polymerase chain reaction (PCR). In this review, we focus our attention on the chemistry of PCR primers. Because PCR is basic technology in biology research fields, we sometimes use chemically labeled primers without any awareness of the chemistry they leave behind. We would like to emphasize that chemically labeled primers contain a lot of potential for different chemistry ideas and much study is still necessary to advance PCR for single-nucleotide polymorphism (SNP) typing, genetic diagnosis, and other fields. Two categories of primers, affinity-capture primers and signaling primers, are discussed from the viewpoints of their chemical concepts and applications. Affinity-capture primers are used for purification, isolation, and manipulation of PCR products by high specificity and affinity to the cognate molecules by molecule molecule interactions, whereas signaling primers report the hybridization and/or progress of PCR amplification by a signal change, in most cases by a fluorescence change. The content of this review may be useful for a better understanding of the chemistry of PCR primers and, more importantly, for the invention of novel PCR chemistry. 相似文献
4.
Prostaglandin D2 is one of five chief prostanoids formed in the cyclooxygenase pathway of arachidonic acid oxidation. Except for a single oxygen atom, PGD2 is structurally identical to 11-dehydro thromboxane B2 (11d-TxB2), a urinary metabolite of the pro-aggregatory platelet activator, thromboxane A2. The close structural relationship suggested that one might be transformed to the other. Accordingly, we tested whether the cyclopentanone of PGD2 can be expanded to the δ-lactone of 11d-TxB2 in a Baeyer-Villiger oxidation. Oxidation of PGD2 with two standard oxidants showed that 11d-TxB2 was formed only with H2O2 but not with peracetic acid. Byproducts of the H2O2-mediated oxidation were hydroperoxide derivatives and isomers of PGD2. Chemical oxidation of PGD2 to 11d-TxB2 may be a model for an equivalent enzymatic transformation, suggesting a possible link in the metabolism of PGD2 and thromboxane A2. 相似文献
5.
A phosphate-selective molecularly imprinted polymer was prepared using 1-allyl-2-thiourea as a functional monomer, and a method
of sensing for phosphate was suggested using an ion-sensitive field-effect transistor (ISFET) or pH meter as a transducer.
The phosphate-selective polymer bound to phosphate selectively, and the ion concentration change or the pH shift in the analyte
solutions after incubation with the imprinted polymer were measured in these systems. In using ISFET electrode, concentration
of phosphate from 10 to 40 μM could be measured selectively. 相似文献
6.
借助三维取向分布函数探讨了高纯超低碳深冲钢板的固溶碳含量对再结晶γ织构的影响,分析了固溶碳与再结晶γ织构及其中的{111}<112>和{111}<110>织构之间的关系 相似文献
7.
Koichi Inoue Shiho Murayama Fumie Seshimo Kazue Takeba Yoshihiro Yoshimura Hiroyuki Nakazawa 《Journal of the science of food and agriculture》2005,85(5):872-878
Apitherapy has become the focus of attention as a form of folk and preventive medicine for treating certain conditions and diseases as well as promoting overall health and well‐being. In apitherapy, honey is the therapeutic agent used for dressing surgical wounds, burns or skin ulcers, as well as for dyspepsia, peptic ulcer, etc., because of its antioxidant activity. Therefore, it is important to determine the antioxidants in honey by analytical techniques. In the present study, the antioxidant activities of honeys from different floral sources were investigated by electron spin resonance (1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and H2O2/NaOH/DMSO scavenging systems), liquid chromatography with coulometric array detection (LC‐ED), and liquid chromatography with electrospray mass spectrometry (LC‐MS). The antioxidant activities of some unifloral honeys (acacia, Chinese milk vetch, buckwheat and manuka) were evaluated using the radical scavenging systems. It was shown that DPPH radical scavenging activity was significantly different among the honeys, with buckwheat and manuka honeys having significantly higher scavenging activity than acacia honey. In addition, only manuka honey had specific scavenging activity for superoxide anion radicals. The compound responsible for this activity in manuka honey was identified by LC‐ED and LC‐MS. Careful examination of the LC‐ED chromatographic patterns of manuka and other honey samples revealed a distinct peak in the chromatogram of manuka honey to be methyl syringate (MSYR). The radical scavenging activity of MSYR was specific for superoxide anion radicals, similar to the case of manuka honey. Copyright © 2005 Society of Chemical Industry 相似文献
8.
The effect of aldehydic lipid peroxidation products on the autoxidation of methyl linoleate (MeL) was studied at 60 °C in bulk phase. Addition of 4-oxo-2-nonenal (ONE) to MeL accelerated the formation of MeL hydroperoxides. Other tested aldehydes showed no effect on the rate of MeL autoxidation. The pro-oxidative effect of ONE disappeared when pre-existing peroxides and transition metals were removed from MeL. Further addition of ferric ion to the peroxide- and metal-free MeL recovered its pro-oxidative effect. ONE reduced ferric ion to ferrous ion effectively. Furthermore, it had a chelating ability with ferrous ion. The results suggest that the pro-oxidative effect of ONE is due to its ability to reduce transition metals and to chelate the reduced form of metal ions. Thus, ONE could accelerate the metal-dependent lipid peroxidation. 相似文献
9.
Dennis N. Kevill Fumie Koyoshi Malcolm J. D’Souza 《International journal of molecular sciences》2007,8(4):346-362
Additional specific rates of solvolysis are determined for phenyl chloroformate. These values are combined with literature values to give a total of 49 data points, which are used within simple and extended Grunwald-Winstein treatments. Literature values are also brought together to allow treatments in more solvents than previously for three N-aryl-N-methylcarbamoyl chlorides, phenyl chlorothionoformate, phenyl chlorodithioformate, and N,N-diphenylcarbamoyl chloride. For the last two listed, moderately strong evidence for a meaningful inclusion of a term governed by the aromatic ring parameter (I) was indicated. No evidence was found requiring inclusion of this parameter for ionization reactions with only one aromatic ring on the nitrogen of carbamoyl chlorides or for the solvolyses of the chloroformate or chlorothionoformate proceeding by an addition-elimination (association-dissociation) mechanism. 相似文献
10.