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排序方式: 共有188条查询结果,搜索用时 15 毫秒
41.
Tani K Ito C Hanawa Y Uchida M Otaguro K Horiuchi H Hiratsuka H 《The journal of physical chemistry. B》2008,112(3):836-844
By use of electrostatic interactions of dye molecules and poly(diallyldimethylammonium chloride) (PDDA), the spin-coating technique has been successfully applied to the preparation of stable J-aggregate thin films of thiacarbocyanine dyes on a polycarbonate or quartz plate. The J-aggregate thin films were prepared by the spin-coating of PDDA aqueous solution on dye thin films prepared on a substrate by the spin-coating of 2,2,3,3-tetrafluoro-1-propanol solution of dyes. Photophysical properties of the dye thin films and J-aggregate thin films were studied by measuring the fluorescence spectra, quantum yields, and lifetimes. Coherent size of the J-aggregates was estimated to be 3-12 by means of the absorption bandwidth (full width at half maximum) or radiative lifetime. Photostability of the J-aggregate thin films was also studied in terms of photodegradation efficiency under argon and oxygen in comparison with the dye thin films, and J-aggregate thin films were found to be more stable than the corresponding dye thin films. 相似文献
42.
Hasegawa T Iijima K Hirota K Nakajima T Makino K Terada H 《Colloids and surfaces. B, Biointerfaces》2008,63(2):209-216
A method for exact determination of phagocytic activity of alveolar macrophage (M) cells toward synthetic microspheres (MS) by optical microscopy was developed. We examined the effectiveness of the treatment of M samples with trypsin, acid or xylene to remove the polystyrene latex microspheres (PSL MS) attached to M cell membranes during their phagocytosis by M cells. We found that centrifugation, which was employed to collect M samples after incubation with MS, affected significantly the efficiency of the various treatments. Of the three treatments, xylene treatment without centrifugation was the most effective to determine the phagocytic activity of M cells, as xylene dissolved the PSL MS on the cell surface almost completely. This treatment was also effective in the case of poly(lactic-co-glycolic acid) MS (PLGA MS), which have been commonly used as an efficient vehicle for drug delivery system. 相似文献
43.
Nagata M Kondo M Suemori Y Ochiai T Dewa T Ohtsuka T Nango M 《Colloids and surfaces. B, Biointerfaces》2008,64(1):16-21
Dialkyl disulfide-linked naphthoquinone, (NQ-Cn-S)2, and anthraquinone, (AQ-Cn-S)2, derivatives with different spacer alkyl chains (Cn: n = 2, 6, 12) were synthesized and these quinone derivatives were self-assembled on a gold electrode. The formation of self-assembled monolayers (SAMs) of these derivatives on a gold electrode was confirmed by infrared reflection-absorption spectroscopy (IR-RAS). Electron transfer between the derivatives and the gold electrode was studied by cyclic voltammetry. On the cyclic voltammogram a reversible redox reaction between quinone (Q) and hydroquinone (QH2) was clearly observed under an aqueous condition. The formal potentials for NQ and AQ derivatives were −0.48 and −0.58 V, respectively, that did not depend on the spacer length. The oxidation and reduction peak currents were strongly dependent on the spacer alkyl chain length. The redox behavior of quinone derivatives depended on the pH condition of the buffer solution. The pH dependence was in agreement with a theoretical value of E1/2 (mV) = E′ − 59pH for 2H+/2e− process in the pH range 3–11. In the range higher than pH 11, the value was estimated with E1/2 (mV) = E′ − 30pH , which may correspond to H+/2e− process. The tunneling barrier coefficients (β) for NQ and AQ SAMs were determined to be 0.12 and 0.73 per methylene group (CH2), respectively. Comparison of the structures and the alkyl chain length of quinones derivatives on these electron transfers on the electrode is made. 相似文献
44.
Single crystals of Rh(Si2O)(PO4)3 and In4(Si2O) · (PO4)6 were prepared by chemical transport reactions in silica tubes and their structures were determined. Crystal data of Rh(Si2O)(PO4)3: trigonal, space group P 3 c1, a = 8.088(3) Å, c = 8.740(2) Å, Z = 2, R(F2) = 0.0379, Rw(F2) = 0.0518 for 601 unique reflections. In4(Si2O)(PO4)6: hexagonal, space group P63/m, a = 8.5149(10) Å, c = 7.7481(12) Å, Z = 1, R(F2) = 0.0436, Rw(F2) = 0.0522 for 509 unique reflections. Both of the compounds have hexagonal close packed array of phosphate groups with metal atoms and SiOSi units in the octahedral interstices, where the SiOSi units show occupational disorder. The structure of the indium compound is considered to be a disordered structure of the reported Mo4Si2P6O13 structure, and contains confacial bioctahedral units. 相似文献
45.
Takehisa Ishimaru 《Journal of fluorine chemistry》2009,130(11):1049-2947
Enantioselective α-sulfenylation of α-fluoro-β-ketoesters 4 with phenylsulfenyl chloride catalyzed by DBFOX-Ph/Ni(II) complex afforded the corresponding α-fluoro-α-sulfenyl-β-ketoesters 2 in moderate to good yields with excellent enantiomeric excesses up to 93% ee. α-Fluoro-α-sulfenyl-β-ketoesters can be effectively converted to tri-fluorinated α-sulfenylcarboxylates by the use of DAST, which should be useful intermediates for the synthesis of non-racemized fluorinated isosteres of pharmaceutically attractive SM32. The enantioselective α-phenylsulfenylation as well as α-pentafluoro-phenylsulfenylation of non-fluorinated β-ketoesters 5 were also carried out under the same catalyst conditions affording up to 95% ee of the products 6-8. 相似文献
46.
In the present study, all-trans retinoic acid (RA) gels formulated with various compositions of polyethylene oxide (Emulgen?) and iota-carrageenan (ι-CG) were prepared and their physicochemical properties were evaluated. The compression energy, which is the work required to compress the product through a fixed distance, increased with increasing amount of ι-CG or Emulgen?. The adhesion energy and displacement decreased with increasing amount of ι-CG or Emulgen? due to the progression of gel formation. From the results of the sensory tests, the properties of RA gels such as adhesiveness, gel strength and spreadability seemed to be adjustable depending on the condition of skin by varying the components of RA gels. Through photostability study, the expiration date and storage conditions of RA gels were determined as "4°C for 28?d with no exposure to light." 相似文献
47.
On a synchronization queue with two finite buffers 总被引:1,自引:0,他引:1
In this paper, we consider a synchronization queue (or synchronization node) consisting of two buffers with finite capacities.
One stream of tokens arriving at the system forms a Poisson process and the other forms a PH-renewal process. The tokens are
held in the buffers until one is available from each flow, and then a group-token is instantaneously released as a synchronized
departure. We show that the output stream of a synchronization queue is a Markov renewal process, and that the time between
consecutive departures has a phase type distribution. Thus, we obtain the throughput of this synchronization queue and the
loss probabilities of each type of tokens. Moreover, we consider an extended synchronization model with two Poisson streams
where a departing group-token consists of several tokens in each buffer.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
48.
49.
Shiro Senrui Atsuro Kodama Masaaki Takehisa 《Journal of polymer science. Part A, Polymer chemistry》1974,12(10):2403-2417
The radiation-induced emulsion polymerization of ethylene in a continuous flow system was carried out at 100°C by using FC-143 and potassium myristate. The polymer concentration in the latex during the course of the polymerization oscillated several times and then approached a steady-state value in a few hours in the case of short residence time. The rate of polymerization was almost constant within the residence time range of 0.2–0.9 hr. This is explained by the kinetics assuming the same mechanism previously proposed in the batch system, that is, the number of polymer particles in this range is considered to be constant. Gel formation was observed at longer reaction times in spite of the continuous supply of myristate micelles, possibly because large polymer particles are produced in this stage. The concentration of carbonyl group in the polymer produced by chain transfer to absorbed myristate ion changes in the same way as the polymer concentration with reaction time. The methyl group in the polymer is produced mainly by chain transfer to the polymer, and the concentration is nearly constant during the polymerization except in the initial stage. The rate constants for the continuous polymerization were very different from the batch polymerization previously studied, despite their similarities in nature. The mass transfer rate of the emulsifier from the micelles to the polymer particles requires future study. 相似文献
50.
Yoshishige Sato Thoru Takahashi Toshio Saito Toshio Sato Masaaki Takehisa 《Radiation Physics and Chemistry》1993,42(4-6):621-624
Radiation sensitivities of
. pumilus and
spores were examined to bremsstrahlung of 5 MeV EB and Cobalt -60 γ rays in order to confirm the effects of radiation and dose rate. Biological indicators (SPORTROL, NAmSA, USA) were irradiated with the X ray in the dose rate range of 4.7–47kGy/h. D-value of
spores was 1.4–1.5 kGy, and that of
was 1.1–1.3 kGy. The D-values of
and
have very small dose rate dependences to X ray, and the D-values are similar to those of γ ray. Dose distribution by X-ray and γ irradiation was measured for cartons containing 32 unit dialyzers. The Dmax./Dmin. of the X-ray irradiation (1.2) was smaller than that of γ ray (1.3). 相似文献