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11.
12.
S. A. Pai K. V. Lohithakshan P. D. Mithapara S. K. Aggarwal 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(3):623-628
Synergistic extraction of hexavalent uranium and plutonium as well as trivalent americium was studied in HNO3 with thenoyl, trifluoro-acetone (HTTA)/1-phenyl, 3-methyl, 4-benzoyl pyrazolone-5 (HPMBP) in combination with neutral donors viz, DPSO, TBP, TOPO (mono-functional) and DBDECMP, DHDECMP, CMPO (bi-functional) with wide basicity range using benzene as dileunt. A linear correlation was observed when the equilibrium constant log Ks for the organic phase synergistic reaction of both U(VI) and Pu(VI) with either of the chelating agents HTTA or HPMBP was plotted vs. the basicity (log Kh) of the donor (both mono- and bi-functional) indicating bi-functional donors also behave as mono-functional. This was supported by the thermodynamic data (G
0, H
0, S
0) obtained for these systems. The organic phase adduct formation reactions were identified for the above systems from the thermodynamic data. In the Am(III) HTTA system log K
s
values of bi-functional donors were found to be very high and deviate from the linear plot (log K
s
vs. log K
h
) obtained for mono-functional donors, indicating that they function as bi-functional for the Am(III)/HTTA system studied. This was supported by high +ve S
0 values obtained for this system. 相似文献
13.
The effect of isomeric butanols on the temperature corresponding to the adiabatic compressibility minimum of water (T β) was studied using a variablepath interferometer working at 3 MHz. The structural contribution to the shift inT β, [ΔT βstr]exp, was found to be positive and to increase with concentration to a maximum atX 2?0.0193, 0.0100, and 0.0090 fort-butanol, sec-butanol, and isobutanol, respectively. The results have been explained on the basis of stabilization of water structure at low concentrations of alcohol. The quantity [ΔT βstr]exp forn-butanol is practically zero at low concentrations, while at high concentrations it is negative, indicating rupture of the hydrogen-bonded structure of water by this solute. At any given concentration,t-butanol > sec-butanol > isobutanol >n-butanol is the order of increasing structural contribution to the shift inT β. Theoretical values of the structural contribution to the shift inT β are in good agreement with the experimental data. 相似文献
14.
Enhanced performance of expanded bed chromatography on rigid superporous adsorbent matrix 总被引:2,自引:0,他引:2
Rigid spherical macroporous adsorbent beads with surface hydroxyl groups were prepared by cross-linking of cellulose. These beads had diameter in the range 100-200 microm and a mean pore size of about 3 microm with about 60% pore volume. The matrix (bulk density approximately 1600 kg m(-3)) could be expanded into a stable bed and used for protein chromatography. Chromatographic runs were performed on a 10 mm diameter column under non-retaining and retaining conditions on the prepared matrix (called Celbeads) and performance of the runs was measured in terms of the height equivalent to a theoretical plate (HETP). The HETP curves in both packed and expanded bed modes followed profiles typical of macroporous adsorbents, i.e. increasing and levelling with velocity. Unimpaired performance of the matrix at increasing flow-rates permitted expanded bed elution of adsorbed solutes without loss of efficiency in terms of purification factor and product concentration. As a model system, Celbeads was used to purify lactate dehydrogenase from porcine muscle homogenate by dye-affinity chromatography. The prepared matrix provided about 100 theoretical plates per meter for the enzyme system at a linear flow velocity of 1.27 cm x min(-1) in an expanded bed elution mode, and gave enzyme yields of 100% with a purification factor of 31 using an optimized procedure. The adsorbent could be cleaned in place with 5 M urea and used repeatedly without loss of performance. 相似文献
15.
K. V. Lohitakshan P. D. Mithapara P. S. Nair S. A. Pai K. Raghuraman A. V. Jadhav H. C. Jain 《Journal of Radioanalytical and Nuclear Chemistry》1994,183(2):359-370
Extraction of trivalent (Pu3+, Am3+, actinides and Eu3+, a representative of lanthanides) and tetravalent (Np4+ and Pu4+) actinides has been studied with dihexyl N,N-di-ethylcarbamoylmethyl phosphonate (DHDECMP) in combination with TBP in benzene from 2M nitric acid. The stoichiometries of the species extracted were found to be M(NO3)3·(3–n) TBP·n DHDECMP (for trivalent ions) and M(NO3)4·(2–n) TBP·n DHDECMP (for tetravalent ions) by the slope ratio method. The extraction constants evaluated (from the distribution data) indicate that for tetravalent ions (with solvation number two) the extraction constant increases when TBP (Kh=0.17) molecules are successively replaced by more basic DHDECMP (Kh=0.34) molecules. However, for trivalent ions (with solvation number three) when TBP molecules are totally replaced by DHDECMP molecules stereochemical factors appear and instead of increase, a substantial decrease in extraction constants is observed for Eu3+ and Am3+, a lesser decrease being observed for Pu3+ (larger ion). 相似文献
16.
17.
V. R. Pai Verneker K. N. Santhanalakshmi 《Journal of polymer science. Part A, Polymer chemistry》1984,22(11):3217-3224
Evidence of the initiation process during uncatalyzed thermal polymerization of vinyl monomers is presented. DSC studies reveal a prominent endothermic effect just before the polymerization exotherm, which is substantiated by the identification of the free radicals produced in the initiation by a quick quenching technique and subsequent detection by ESR at low temperatures. 相似文献
18.
A. Ait Haddou M. Berrada G. Paić 《Journal of Radioanalytical and Nuclear Chemistry》1986,102(1):159-175
The yield and average cross section for the reactions11B(p, n)11C,12C(p, )13N,13C(p, n)13N,
12
12
C(d, n)13N,14N(p, )11C,16O(p, )13N,16O(d, n)17F,16O(t, n)18F, and18O(p, n)18F have been measured in different compounds. The charged particles were created in the samples themselves either through recoil by scattering of 14 MeV neutrons off hydrogen and deuterium, or by the (n, t) reaction on6Li using thermal neutrons. The yields of reactions12C(d, n);16O(p, );16O(t, n) and18O(p, n) have been measured using proton, deuteron and triton spectra generated by 14 MeV neutrons in the reactions D(n, p)2n;6Li(n, d);7Li(n, d) and10B(n, d);7Li(n, t) and10B(n, t), respectively. 相似文献
19.
Measurements have been carried out of the elastic constants of SrO in the virgin undoped state and of the changes produced in them by equilibrium doping with oxygen at ? 1200°C and oxygen partial pressure of 0.95 atm. The method used was Papadakis' pulse-echo overlap technique in conjunction with thermogravimetric analysis (T.G.A.) to determine mass and density changes due to oxygen doping.The values obtained for C11, C12 and C44 of the virgin crystal at 23°C are ;;.(These values are in very good agreement with those of Son and Bartels [2].)Values for and were found to be ?1.74% and ?0.86% respectively. Accurate valu could not be obtained because of sample size limitations after quenching. However, C12 was shown to definitely increase due to doping.Analysis of the results indicate that the elastic modulus changes can only be attributed to the formation of cation vacancies during doping. Analysis of the T.G.A. behavior indicates that this cation vacancy formation is probably associated with the presence of various tripositive cation and uninegative anion species depending upon the impurity concentrations of the sample. This implied impurity-controlled cation vacancy concentration is consistent with the earlier observed extrinsic nature of cation diffusion in SrO at 1200°C. 相似文献
20.
Shi-He Luo Qun-Fang Wang Zhao-Yang Wang Pai Peng 《Research on Chemical Intermediates》2013,39(6):2513-2526
Using 4′-hexyloxybiphenyl-4-ol and N-(5-alkoxy-3-bromo-2(5H)-furanonyl) amino acids as reactants, a series of novel biphenyl liquid crystal compounds containing natural molecule moieties, such as menthol, borneol, and amino acids, were synthesized via esterification. The structures of all novel compounds were confirmed by FTIR, 1H NMR, 13C NMR, MS, and elemental analysis, and the liquid crystal properties of target compounds were characterized with DSC, XRD, and POM. The introduction of hexyloxy made the biphenyl esters have a potential to appear in mesomorphic phase and have a higher Tm, and bornyl moiety was more beneficial for the liquid crystal performance than a menthyl unit. Most compounds were mesomorphic phase liquid crystal molecules, and POM and XRD showed that they existed in smectic phase. These researches provide a theoretical basis for the synthesis of biphenyl ester liquid crystal materials via the utilization of 2(5H)-furanone derivates and natural molecules. 相似文献