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31.
JPC – Journal of Planar Chromatography – Modern TLC - A new stability-indicating HPTLC assay has been established for leuprolide acetate. Silica gel 60F254 was used as stationary phase.... 相似文献
32.
Chrome azurol S immobilised on XAD-2 has been used in this study as a reagent phase for the development of an optical fibre Al(III) sensor. Using a kinetic approach, this sensor was able to give a linear response in the Al(III) concentration range of 1.3 x 10(-5)-2.0 x 10(-4) M with a limit of detection of 1.0 x 10(-4) M. The optimum responses were obtained at pH 6.0 and when the solution was stirred. The sensor response was found to have a repeatability and reproducibility of 1.6% and 5.8%, respectively. The results obtained for Al(III) determination in aqueous sample were in good agreement with those obtained using graphite furnace-atomic absorption spectrometry. 相似文献
33.
Muhammad Ilyas Sarwar Sonia Zulfiqar Zahoor Ahmad 《Colloid and polymer science》2007,285(15):1733-1739
Fluoro-aramid-based sol/gel-derived nanocomposites were synthesized by condensing a mixture of 4,4′-(hexafluoro-isopropylidene)dianiline
and 1,3-phenylenediamine with terephthaloylchloride (TPC) in dimethylacetamide. TPC was added in slight excess to produce
amide chains with carbonyl chloride end groups and then replaced with alkoxy groups using aminophenyltrimethoxysilane to develop
bonding with the silica network. Mechanical, dynamic mechanical thermal, water absorption and morphological measurements were
carried out on the thin hybrid films. Increase in the tensile strength and modulus was observed as compared to pristine polyamide.
The thermal decomposition temperature was found in the range of 400–500 °C. The water absorption was found to be reduced with
higher silica content. The glass transition temperature and the storage moduli increased with increasing silica concentration.
The maximum increase in the T
g value (345 °C) was observed with 20 wt% silica. Scanning electron microscopy revealed the uniform distribution of silica
in the matrix with an average particle size ranging from 8 to 50 nm. 相似文献
34.
Characteristic fragment ions obtained in Fast atom bombardment (FAB) mass spectroscopy of ribose alkylated Uridine 5'-monophosphate (5'-UMP) derivatives in negative ion mode are described. All the compounds examined exhibited either [M]- or quasimolecular ion [M - H]- the fragmentations can be used to characterize these nucleotides. 相似文献
35.
Fluorescence quenching by molecular oxygen has been employed to estimate dynamic parameters and solubility characteristics of molecular oxygen in micelle forming detergent solutions. A kinetic model which assumes that oxygen quenching occurs only in the micellar phase is employed to analyze the data. 相似文献
36.
Ahmad I Fasihullah Q Vaid FH 《Journal of photochemistry and photobiology. B, Biology》2004,75(1-2):13-20
The photodegradation reactions of riboflavin (RF) in the presence of 0.05-2.00 M phosphate (pH 7.0) have been studied using a specific multicomponent spectrophotometric method. The reactions involve simultaneous photolysis (intramolecular photoreduction) and photoaddition (intramolecular photoaddition) leading to lumichrome (LC) and cyclodehydroriboflavin (CDRF), respectively, as major products. The contribution of each reaction in the overall photodegradation depends upon the phosphate concentration, i.e., higher the phosphate concentration higher the extent of photoaddition. The apparent first-order rate constants for the photodegradation of RF and for the formation of LC and CDRF at 0.25-2.00 M phosphate concentration range from 0.65 to 3.03 x 10(-2), and from 0.41 to 0.99 x 10(-2) and 0.12 to 1.63 x 10(-2) min(-1), respectively. The second-order rate constants for the phosphate catalysed photodegradation of RF and for the formation of LC and CDRF are 2.12 x 10(-4) and 0.61 x 10(-4) and 1.41 x 10(-4) M(-1)s (-1), respectively. Since the formation of CDRF by photoaddition is catalysed by HPO(4)(2-) ions, it is suggested that H(2)PO(4)(-) ions may be involved in the formation of LC by photolysis. Thus, both H(2)PO(4)(-) and HPO(4)(2-) ions may catalyse the two major reaction pathways of riboflavin photodegradation, respectively. 相似文献
37.
The reaction of Cα,O-Dilithiooximes 2 and α-chloroketones afforded 5-(hydroxymethyl)-Δ2-soxazolines 4 . α,β-Unsaturated aldehydes and ketones reacted with 2 to give the corresponding acyclic 1,2-addition products 5 . The latter were cyclized with phosphorus pentoxide to 5-vinyl-Δ2-isoxazolines 6 . 相似文献
38.
Effects of relative humidity conditions in the irradiation chamber and of temperature of the chamber on the response of 3 mm thick light blue poly (methyl methacrylate) sheets have been studied. The response was measured spectrophotometrically at 402, 450, 596 and 612 nm. The response of the dosimeter is independent of the relative humidity (12–97%) during irradiation if the response is measured within 24 h of irradiation. If the response is measured after longer storage time, the absorbance at 402 and 450 nm increases significantly. At these two wavelengths the response of the dosimeter is also independent of the temperature of the irradiation chamber in the range of 0 to 40 °C. However, at higher temperatures (60, 80 °C), the response is not uniform. 相似文献
39.
Sonia Jam Masume Ghalbi Ahangary Ahmad Tavasoli Kambiz Sadaghiani Ali Nakhaei Pour 《Reaction Kinetics and Catalysis Letters》2006,89(1):71-79
Summary An integrated process for producing liquid fuels from synthesis gas via a two-stage Fischer-Tropsch (FT) reaction is disclosed. An iron catalyst was used in the first bed of a fixed-bed reactor
followed by a ruthenium promoted cobalt catalyst in the second bed. The activity and selectivity of the dual-bed system were
assessed and compared with those using catalysts in a single bed system, separately. The methane selectivity in the dual-bed
reactor was about 11% less compared to that of the single-bed system. The C5+ selectivity for the dual-bed reactor was 19.7% higher than that of the single-bed system. 相似文献
40.
M. S. Chaudhary S. Ahmad A. Mannan I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1984,83(2):387-396
An instrumental neutron activation analytical (INAA) technique is described for the determination of 26 toxic and other trace elements in Eastern Coal (NBS SRM-1632a), local coal and its ash. The coal ash was produced by heating coal at 750°C in a muffled furnace. The transfer of these elements to the environment on the complete compustion of coal is estimated from the difference between the elemental concentration of coal and its ash. 相似文献