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71.
Muraoka T Abe K Haga Y Nakamura T Ueno K 《Journal of the American Chemical Society》2011,133(39):15365-15367
Base-stabilized silanone complex Cp*(OC)(2)W(SiMe(3)){O═SiMes(2)(DMAP)} (2) was synthesized by the reaction of (silyl)(silylene)tungsten complex Cp*(OC)(2)W(SiMe(3))(═SiMes(2)) (1) with 1 equiv of pyridine-N-oxide (PNO) in the presence of 4-(dimethylamino)pyridine (DMAP). Further oxygenation of 2 with 3 equiv of PNO at 80 °C resulted in the formation of a W-O-Si-O-Si framework to give disiloxanoxy complex Cp*(O)(2)W{OSiMes(2)(OSiMe(3))} (3). Complex 3 was also obtained by the direct reaction of complex 1 with 4 equiv of PNO at 80 °C. 相似文献
72.
Kazuo Sugiyama Kohei Shiraishi Takako Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》2003,41(13):1992-2000
Poly[2‐(methacryloyloxy)ethyl phosphorylcholine]s (PMPCs) with one pendant cholesteryl moiety at the polymer end (PMPC‐Chol‐I and PMPC‐Chol‐II) and two pendant cholesteryl moieties at both polymer ends as terminal groups (PMPC‐2Chol‐I and PMPC‐2Chol‐II) were prepared by the radical polymerization of 2‐(methacryloyloxy)ethyl phosphorylcholine initiated with 4,4′‐azobis[(3‐cholesteryl)‐4‐cyanopentanoate] in the presence of 2‐mercaptoethanol or thiocholesterol as chain‐transfer reagents, respectively. The self‐organization of PMPC‐Chol and PMPC‐2Chol was analyzed with fluorescence and 1H NMR measurements. The critical micelle concentrations of PMPC‐Chol‐I with a degree of polymerization (Pn) of 91 and of PMPC‐2Chol‐I with a Pn value of 165 were 250 and 27 mg L?1, respectively. The blood compatibility of PMPC‐2Chol was evaluated from the Michaelis constant (Km) for the enzymatic reaction of thrombin and a synthetic substrate, S‐2238, in the presence of PMPC‐2Chol. Km was 0.07, 0.05, and 0.56 for PMPC‐2Chol‐I with Pn = 165, PMPC‐2Chol‐II with Pn = 38, and PMPC (an intrinsic viscosity of 0.54 dL g?1) initiated with 2,2′‐azobisisobutyronnitrile in the absence of chain transfer agent, respectively. A mixture of PMPC‐2Chol‐II and cholesterol as a drug model formed a lamellar type of complex with an interplanar spacing of d = 35.2 Å. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1992–2000, 2003 相似文献
73.
A simple and highly sensitive spectrophotometric method for the determination of biologically active thiols based on the fading of eosin-silver(I)-adenine ternary complex was established. In the determination of 6-mercaptopurine (MP), Beer's law was obeyed in the range 0.02-0.30 microg ml(-1), with an effective molar absorptivity at 562 nm and the relative standard deviation being 3.5 x 10(5) dm3 mol(-1) cm(-1) and 0.72% (n = 5). Analytical data for various biologically active thiols were determined with the proposed method. This method is about 5-10 times more sensitive than the conventional spectrophotometric methods. A compound having a disulfide bond (-S-S-), such as cystine, could also be determined by the conversion of disulfides to free thiols with the sulfite ion. The procedure was successfully applied to assays of various biologically active thiols in actual medicines. 相似文献
74.
Zameer Shervani Yutaka Ikushima Masahiro Sato Hajime Kawanami Yukiya Hakuta Toshirou Yokoyama Takako Nagase Hironobu Kuneida Kenji Aramaki 《Colloid and polymer science》2008,286(4):403-410
We have employed a number of reducing and capping agents to obtain Ag(0) metallic nanoparticles of various sizes and morphologies.
The size and morphology were tuned by selecting reducing and capping agents. Spherical particles of 15 and 43 nm diameter
were obtained when 1 wt% aqueous starch solution of AgNO3 precursor salt was reduced by d(+)-glucose and NaOH, respectively, on heating at 70 °C for 30 min. Smaller size particles obtained in the case of d(+)-glucose reduction has been attributed to the slow reduction rate by mild reducing agent d(+)-glucose compared to strong NaOH. Conducting the reduction at ambient temperature of silver salt in liquid crystalline
pluronic P123 and L64 also gave spherical particles of 8 and 24 nm, respectively, without the addition of any separate reducing
agent. NaOH reduction of salt in ethylene glycol (11 g)/polyvinyl pyrolidone (PVP; 0.053 g) mixture produced large self-assembled
cubes of 520 nm when smaller (26–53 nm) star-shaped sharp-edged structures formed initially aggregated on heating the preparation
at 190 °C for 1 h. Increasing the amount of PVP (0.5 g) in ethylene glycol (11 g) and heating at 70 °C for 30 min yielded
a mixture of spherical and non-spherical (cubes, hexagons, pentagons, and triangle) particles without the addition of an extra
reducing agent. Addition of 5 wt% PVP to 1 wt% aqueous starched solution resulted in the formation of a mixture of spherical
and anisotropic structures when solution heated at 70 °C for 1 h. Homogeneous smaller sized (29 nm) cubes were synthesized
by NaOH reduction of AgNO3 in 12.5 wt% of water-soluble polymer poly(methyl vinyl ether) at ambient temperature in 30 min reaction time. 相似文献
75.
Takako Yamashita Dr. Yosuke Matsuo Dr. Yoshinori Saito Prof. Dr. Takashi Tanaka 《化学:亚洲杂志》2021,16(13):1735-1740
Hexahydroxydiphenoyl (HHDP) and dehydrohexahydroxydiphenoyl (DHHDP) groups are the major acyl components of ellagitannins, which are polyphenols whose biosynthesis have attracted considerable attention; however, the mechanisms of the production of HHDP and DHHDP in the ellagitannin biosynthesis have not been clarified. With the aim of elucidating such a mechanism, this study investigates the CuCl2-mediated oxidation of simple galloyl derivatives in an aqueous medium. It is shown that the oxidation of methyl gallate affords a DHHDP-type dimer, whose reduction with Na2S2O4 yields an HHDP-type dimer. However, the oxidation of the HHDP-type product over CuCl2 does not afford the parent DHHDP ester. The oxidation of 1,4-butanediol digallate under the same conditions produces a DHHDP-type product via the intramolecular coupling of galloyl groups. These results strongly suggest that the DHHDP group is the initial product of the oxidative coupling of two galloyl groups in the ellagitannin biosynthesis, and subsequent reductive metabolism affords HHDP esters. 相似文献
76.
We devised a new method of data mining for a large-scale database. In the method, a network of locally coupled phase oscillators subject to Kuramoto's model substitutes for given multivariate data to generate major features through phase locking of the oscillators, i.e., phase transition of the data set. We applied the method to the national database of care needs certification for the Japanese public long-term care insurance program, and found three major patterns in the aging process of the frail elderly. This work revealed the latent utility of Kuramoto's model for data processing. 相似文献
77.
Takahide Y Konoike T Enomoto K Nishimura M Terashima T Uji S Yamamoto HM 《Physical review letters》2007,98(11):116602
We report a large positive magnetoresistance ratio in insulating organic crystals theta-(ET)(2)CsZn(SCN)(4) at low temperatures at which they exhibit highly nonlinear current-voltage characteristics. Despite the nonlinearity, the magnetoresistance ratio is independent of the applied voltage. The magnetoresistance ratio depends little on the magnetic field direction and is described by a simple universal function of mu(B)B/k(B)T, where mu(B) is the Bohr magneton. The positive magnetoresistance may be caused by magnetic-field-induced parallel alignment of spins of mobile and localized electrons, and a resulting blockade of electrical conduction due to the Pauli exclusion principle. 相似文献
78.
[reaction: see text] In the presence of 5 mol % of niobium(V) chloride, alpha,alpha,alpha-trifluorotoluene derivatives were reduced with lithium aluminum hydride to give toluene derivatives in good yields. Stepwise, partial reduction of bis(trifluoromethyl)benzene derivative was also demonstrated. 相似文献
79.
Ikeda K Kubo A Akahoshi N Yamada H Miura N Hishiki T Nagahata Y Matsuura T Suematsu M Taguchi R Ishii I 《Analytical and bioanalytical chemistry》2011,400(7):1853-1863
Fatty liver is one of the typical manifestations in homocysteinemia/homocystinuria patients and their genetic animal model, mice lacking cystathionine ??-synthase (Cbs ?/?). The vast majority of Cbs ?/? die within 4?weeks after birth via yet unknown mechanisms, whereas a small portion survive to adulthood, escaping fatty degeneration of the liver during lactation periods, through regeneration. To investigate the molecular basis of such fatty changes, we analyzed lipid components in fatty livers of 2-week-old Cbs ?/? and regenerated non-fatty livers of 8-week-old Cbs ?/? survivors using a chip-based nanoESI (electrospray ionization)-MS system, which allows quantitative detection of triacylglycerol/phospholipid molecular species. Hepatic levels of all major triacylglycerol species were much higher in Cbs ?/? than in wild-type mice at 2?weeks, although not at 8?weeks. Levels of some phospholipid species were either up- or downregulated in 2-week-old Cbs ?/?; e.g. saturated (16:0 and 18:0) or mono-unsaturated (16:1 and 18:1) fatty acids-containing phosphatidylcholine/phosphatidylethanolamine species were upregulated, while poly-unsaturated fatty acids-containing phosphatidylcholine (18:2?C18:2 and 18:2?C20:5), phosphatidylethanolamine (18:1?C20:4), and phosphatidylinositol (18:0?C20:4) were downregulated. Capillary electrophoresis-MS analysis identified high-level accumulation of S-adenosylmethionine and S-adenosylhomocysteine in fatty livers of 2-week-old Cbs ?/? but much less in non-fatty livers of 8-week-old Cbs ?/?. Although hepatic S-adenosylmethionine/S-adenosylhomocysteine ratios were comparable between 2-week-old Cbs ?/? and wild-type, global protein arginine methylation was disturbed in fatty livers of Cbs ?/?. Our results suggest that cellular signaling mediated by altered phospholipid contents might be involved in pathogenesis of fatty liver in Cbs ?/?C. 相似文献
80.
Hasegawa S Saito S Takanashi J Morokoshi Y Furukawa T Saga T Aoki I 《Magnetic resonance imaging》2011,29(2):179-184
Aberrant expression of ferritin, a major iron-binding protein, has shown to be involved in neurodegenerative diseases. In this study, we generated transgenic (Tg) mice of human ferritin heavy chain (FTH) gene and investigated the effects of ferritin overexpression in FTH-Tg brain by 1H-MRI and 1H-MRS. The mice displayed no apparent neurological symptoms, and no specific morphological and T2 alterations were found in the brain by MRI, and not even by histological studies. 1H-MRS, however, revealed that some metabolic markers were significantly altered in FTH-Tg brains compared to wild-type control brains, such as decreases in myo-inositol and glutamine, and an increase in lactate. Our present studies suggested that despite the absence of neurological, morphological, T2, and histological signatures, brain metabolisms were significantly affected in FTH-Tg mice. This study also highlights the usefulness of 1H-MRS in the analysis of transgenic mouse models. 相似文献