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121.
Kalyan Kali Sen Gupta Ambikesh Mahapatra Balaram Ghosh 《Transition Metal Chemistry》1991,16(5):500-502
Summary The reactivities of - and -glycerophosphates towards MnO
4
–
in HClO4 medium have been examined. The reactions between glycerophosphates and MnO
4
–
are first order with respect to [glycerophosphate], [MnO
4
–
] and [H+]. There is no evidence for cleavage of the C–O–P bond rather than the terminal –CH2OH group being oxidized to the respective phosphoglyceraldehyde. 相似文献
122.
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125.
The progress of high temperature processes is generally described in terms of variation of the degree of conversion () with time (t). The present paper outlines a procedure for making use of-t plots for comparative assessment of productivity and energy requirements for a test system with respect to a reference, on the basis of some simplifying assumptions. It is assumed that the throughput is inversely proportional to reaction time as in the case of batch reactors and plug flow reactors. It is also assumed that the energy requirement is a simple function of process temperature. The principles outlined is illustrated with reference to some laboratory data for reduction of iron oxide by coal.The authors wish to thank Prof. P. R. Rao, Director National Metallurgical Laboratory, Jamshedpur, India, for providing facilities for experimental work and for according permission to publish this work. 相似文献
126.
127.
The mixed-ligand complexes formed by copper(II) with an amino-acid (valine, threonine, isoleucine, aspartic acid, glutamic acid, lysine) and malonic acid have been investigated polarographically and their stability constants determined. The complexes are less stable than the corresponding complexes with oxalic acid instead of malonic, but also exhibit less disproportionation into the simple complexes, because the simple oxalate complexes are more stable than the malonate complexes. 相似文献
128.
A systematic quantum mechanical study of the possible conformations, their relative stabilities, vibrational and electronic
spectra and thermodynamic parameters of methyl-3-methoxy-2-propenoate has been reported for the electronic ground (S0) and first excited (S1) states using time-dependent and time-independent Density Functional Theory (DFT) and RHF methods in extended basis sets.
Detailed studies have been restricted to the E-isomer, which is found to be substantially more stable than the Z-isomer. Four
possible conformers c′Cc, c′Tc, t′Cc, t′Tc, of which the first two are most stable, have been identified in the S0 and S1 states. Electronic excitation to S1 state is accompanied with a reversal in the relative stability of the c′Cc and c′Tc conformers and a substantial reduction
in the rotational barrier between them, as compared with the S0 state. Optimized geometries of these conformers in the S0 and S1 states are being reported. Based on suitably scaled RHF/6-31G** and DFT/6-311G** calculations, assignments have been provided to the fundamental vibrational bands of both these conformers in terms of frequency,
form and intensity of vibrations and potential energy distribution across the symmetry coordinates in the S0 state. A complete interpretation of the electronic spectra of the conformers has been provided. 相似文献
129.
A highly sensitive spectrophotometric method for the determination of nitrite in water and soil has been developed. The reaction of nitrite with acidified potassium iodide to liberate iodine which oxidizes leuco‐crystal violet (LCV) to form crystal violet having absorption maxima at 590 nm forms the bases of this method. In aqueous medium the system obeys Beer's law in the range of 0.1 to 1.0 μg per 25 mL (0.004–0.04 ppm), while in an extractive system the range is 0.025–0.25 μg in 100 mL (0.00025–0.0025 ppm). The molar absorptivity and Sandell's sensitivity were found to be 1.54 × 106 1 mol?1 cm?1 and 44 pg cm?2, respectively. 相似文献
130.
A detailed study for the spectrophotometric readout method for L-threonine powder, [CH3CH(OH)CH(NH2)COOH], was done. In this method, 400 mg unirradiated/irradiated L-threonine powder was dissolved in 10 ml of a solution which contains 3×10−4 mol dm−3 ferrous ammonium sulphate and 1.7×10−4 mol dm−3 xylenol orange (XO) in aerated aqueous 0.17 mol dm−3 sulphuric acid (FX). The peroxy radicals produced from irradiated threonine oxidize ferrous ions and XO forms a complex with ferric ions as well as controls the chain length of ferrous ion oxidation. The plot of absorbance at 556 nm against dose is linear in the dose range 20–400 Gy and doses down to about 1 Gy can be measured using 10-cm path cells. Response of the dosimeter is independent of irradiation temperature above 20. A dose of 50 Gy–10 kGy can be measured dissolving 50 mg threonine powder in 10 ml of a solution which contains 3×10−4 mol dm−3 ferrous ammonium sulphate and 1.3×10−4 mol dm−3 XO in aerated aqueous 0.06 mol dm−3 sulphuric acid (FX). The plot of absorbance at 552 nm against dose is non-linear. However dosimeter shows linear dose response up to 1000 Gy. Irradiated threonine powder is stable for about 3 months. The reproducibility of the method is better than ±2%. This dosimeter is very useful as transfer dosimeter for food irradiation programme. 相似文献