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991.
Siti Sarah Abdul Rahman Daisuke Kawaguchi Daisaku Ito Atsushi Takano Yushu Matsushita 《Journal of Polymer Science.Polymer Physics》2009,47(22):2272-2280
The phase behavior of statistical copolymers composed of (4‐tert‐butylstyrene) (B) and (4‐tert‐butoxystyrene) (O), abbreviated as s‐BO, with polyisoprene (I) was investigated by optical microscopic (OM) observation and small‐angle neutron scattering (SANS) measurements. It has been known that B/I blend shows lower critical solution temperature (LCST) type phase diagram, while O/I blend has upper critical solution temperature (UCST) type one. Several blends of s‐BOs having mol fraction of B, mB, comparable to 0.50, with I showed both UCST and LCST type phase diagram. Furthermore, UCST type phase behavior was observed for blends having small mB, while LCST type one was for that of large mB at all used temperatures. Hence, the phase behavior of s‐BO/I blend can be understood as a result of the competition of two interactions having opposite temperature dependence. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2272–2280, 2009 相似文献
992.
Mahmood Tajbakhsh Rahman Hosseinzadeh Farhad Ramzanian‐Lahmali Marzieh Sadatshahabi 《中国化学会会志》2005,52(5):1005-1009
2,6‐Dicarboxypyridinium fluorochromate as a new, rapid, and efficient reagent was prepared and used for the oxidative deprotection of oximes, phenylhydrazones, and semicarbazones to their carbonyl analogues under solvent‐free conditions at room temperature. 相似文献
993.
We studied reaction of oxygen atoms with D-terminated Si(1 1 1) surfaces from a desorption point of view. As the D (1 ML)/Si(1 1 1) surface was exposed to O atoms D2 and D2O molecules were found to desorb from the surface. The desorption kinetics of D2 and D2O molecules exhibited a feature characterized with a quick rate jump at the very beginning of O exposure, which was followed by a gradual increase with a delayed maximum and then by an exponential decrease. The O-induced D2 desorption spectra as a function of Ts appeared to be very similar to the H-induced D2 desorption spectrum from the D/Si(1 1 1) surfaces. Possible mechanisms for the O-induced desorption reactions were discussed. 相似文献
994.
995.
Md Mustafizur Rahman Kaoru Fujinaga Yasushi Seike Minoru Okumura 《Analytical sciences》2004,20(1):165-170
A simple in situ visual and tristimulus colorimetric method for the determination of trace arsenic in environmental water after collecting arsenic on a test paper impregnated with mercury(II) bromide and rosaniline chloride by its reduction aeration has been developed. The color development on the test paper is based on the formations of AsH(HgBr)2 (yellow) and/or As(HgBr)3 (brownish yellow) by a reaction between mercury(II) bromide and arsine (AsH3), which is produced through the reduction of As(III) (arsenite ion) and/or As(V) (arsenate ion) in a sample solution. To a sample solution, potassium iodide, tin(II) chloride, zinc sand and 4 ml of 6 M hydrochloric acid solution were added successively. The liberated arsine was collected on the test paper. The yellow or brownish-yellow color intensity on the test paper was measured by a tristimulus colorimeter and also by a visual method. The established method is applicable to the determination of arsenic in environmental water sample such as river, brackish, and seawater types. 相似文献
996.
M. Rahman 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1996,47(4):601-615
The elastodynamic problem of a rigid punch moving at a constant sub-Rayleigh speed across the surface of an elastic half-space is investigated in the present paper. The unknown contact region is determined as part of solution from the unilateral or Signorini conditions. Numerical results are plotted showing how the eccentricity of the contact ellipse changes with the punch speed. Some asymptotic properties of the solution for the case where the punch speed is comparable with the Rayleigh wave speed are explored in details. 相似文献
997.
A simple kinetic spectrophotometric method is described for the determination of famotidine. The method is based on the oxidation of the drug with alkaline potassium permanganate. The reaction is followed spectrometrically by measuring the rate of change of the absorbance at 610 nm. The initial-rate and fixed-time (at 12 min) methods are adopted for determining the drug concentration. The calibration graphs are linear in the ranges of 2-10 microg mL(-1) and 1-8 microg mL(-1) using the initial-rate and fixed-time methods, respectively. The method has been applied to the determination of famotidine in tablet formulations. The obtained results are compared statistically with those given by a reference spectrophotometric method. 相似文献
998.
Analytic solutions are obtained by solving the conservation equations describing fully developed parabolic laminar flow with heat transfer to predict the axial velocity profile, the temperature distribution and the secondary flow behaviour in a square duct. The biharmonic equation arising in this problem has been solved by using the Navier method for simply supported rectangular plates. The analytic solutions substantially agree with the available experimental results. 相似文献
999.
Nisar Ahmad Bilal Haider Abbasi Inayat ur Rahman Hina Fazal 《Applied biochemistry and biotechnology》2013,169(7):2004-2015
A reliable in vitro regeneration system for the economical and medicinally important Piper nigrum L. has been established. Callus and shoot regeneration was encouraged from leaf portions on Murashige and Skoog (MS) medium augmented with varied concentrations of plant growth regulators. A higher callus production (90 %) was observed in explants incubated on MS medium incorporated with 1.0 mg?L?1 6-benzyladenine (BA) along with 0.5 mg?L?1 gibberellic acid after 4 weeks of culture. Moreover, a callogenic response of 85 % was also recorded for 1.0 mg?L?1 BA in combination with 0.25 mg?L?1 α-naphthalene acetic acid (NAA) and 0.25 mg?L?1 2,4-dichlorophenoxyacetic acid or 0.5 mg?L?1 indole butyric acid (IBA) along with 0.25 mg?L?1 NAA and indole acetic acid. Subsequent sub-culturing of callus after 4 weeks of culture onto MS medium supplemented with 1.5 mg?L?1 thiodiazoran or 1.5 mg?L?1 IBA induced 100 % shoot response. Rooted plantlets were achieved on medium containing varied concentrations of auxins. The antioxidative enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] revealed that significantly higher SOD was observed in regenerated plantlets than in other tissues. However, POD, CAT, and APX were higher in callus than in other tissues. A high-performance liquid chromatography (HPLC) fingerprint analysis protocol was established for quality control in different in vitro-regenerated tissues of P. nigrum L. During analysis, most of the common peaks represent the active principle “piperine.” The chemical contents, especially piperine, showed variation from callus culture to whole plantlet regeneration. Based on the deviation in chromatographic peaks, the in vitro-regenerated plantlets exhibit a nearly similar piperine profile to acclimated plantlets. The in vitro regeneration system and HPLC fingerprint analysis established here brought a novel approach to the quality control of in vitro plantlets, producing metabolites of interest with substantial applications for the conservation of germplasm. 相似文献
1000.
M. W. Rahman M. M. Hossain M. J. Alam N. C. Dafader M. E. Haque 《International Journal of Polymer Analysis and Characterization》2013,18(7):479-487
The effect of transition metals as a promoter of physico-mechanical properties of radiation-vulcanized natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of transition metals (Fe, Mn, etc.) of different concentrations (0–30 ppm) in natural rubber (NR) latex and irradiated with various radiation doses (0–20 kGy). The concentrations of metal ions and radiation doses were optimized and found to be 20 ppm and 12 kGy, respectively. Tensile strength, tear strength, and cross-linking density of the irradiated rubber films were increased with increasing concentration of metal ions as well as radiation doses. The mechanical properties of the films were enhanced by approximately 20% at the optimum conditions. In contrast, elongation at break, permanent set, and swelling ratio of the films were decreased under the same conditions. The comparative effect of metal ions can be explained by Fajan's rules, reported in this article. 相似文献