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排序方式: 共有183条查询结果,搜索用时 15 毫秒
1.
M. M. Charyulu K. Venugopal Chetty D. G. Phal Veena Sagar SagarD. M. Sagar S. M. Pawar R. Swarup V. V. Ramakrishna V. Venugopal 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):153-154
Recovery of americium from nitric acid solutions was studied by co-precipitation as hydroxide with various ions like calcium, ferric, nickel using sodium hydroxide and ammonium hydroxide. Studies were also carried out to recover americium using lanthanum fluoride and bismuth phosphate co-precipitation. All the methods are able to co-precipitate Am quantitatively. However, co-precipitation of Am with optimum concentration iron using ammonia is found to be better from nitric acid solutions containing large concentrations of calcium ions. Approximately 2 g of Am was recovered from 150 litres of solution batch wise using iron. 相似文献
2.
The carbamoyl methyl sulfoxide compounds of uranyl bis(β-diketonate) of the types [UO2(DBM)2CMSO] and [{UO2(DBM)2}2CMSO] (where HDBM = C6H5COCH2COC6H5; CMSO = C6H5CH2SOCH2CONHC6H5 or C6H5SOCH2CONiPr2) have been synthesized and characterized by IR and NMR spectroscopic techniques and elemental analysis. Spectral studies show that CMSO acts as a monodentate ligand in [UO2(DBM)2CMSO] compounds and bonds through the sulfoxo oxygen atom to the uranyl group. It acts as a bridging bidentate ligand in [{UO2(DBM)2}2CMSO] compounds and bonds through both the sulfoxo and carbamoyl oxygen atoms to two different uranyl groups. The structure of the compound [{UO2(DBM)2}2C6H5CH2SOCH2CONHC6H5] confirms the bridging bidentate mode of coordination for the CMSO ligand. Extraction studies show an enhancement in solvent extraction for the uranyl ion from nitric acid medium when a mixture of thenoyl trifluoroacetone (HTTA) and CMSO was employed. 相似文献
3.
A. N. Chetty P. Ramadevi G. R. K. Naidu 《Journal of Radioanalytical and Nuclear Chemistry》1987,117(6):347-352
Isotope exchange behaviour of bis/diethyl dithiocarbamate/ copper/II/ complex has been studied at 30 °C and 40 °C varying the concentration of the complex and metal ion. Results indicate that the complex is labile in chloroform dimethyl sulphoxide medium. Increase in concentration has significant effect on the rate of the reaction. Similarly the increase in temperature increased the rate of the reaction. 相似文献
4.
H. D. Whitley W. E. Alley W. H. Cabot J. I. Castor J. Nilsen H. E. DeWitt† 《等离子体物理论文集》2015,55(5):413-420
The equation of state of binary ionic mixtures of similar ions, such as nitrogen, oxygen and carbon, has been extensively studied. The study of dense asymmetric mixtures, where Z2 >> Z1, has primarily focused on mixtures of hydrogen and iron at solar conditions. Using molecular dynamics simulations, we examine the behavior of highly asymmetric binary ionic mixtures, where the coupling of the high‐Z species may be orders of magnitude higher than the coupling of the low‐Z species. For the conditions we have studied, we find that strong correlations and signatures of solidification occur in the high‐Z species, while the low‐Z species exists as a freely flowing fluid within the high‐Z solid matrix. Solidification of the low‐Z species is correlated with the coupling between the two components. Using the Widom expansion method, we compute the plasma screening enhancement of the nuclear reaction rates for Z = 1 in a high‐Z matrix. We also provide some estimates of the coefficient of binary diffusion in the mixture. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
The specific surface area of mercuric sulphide (a) has been determined by three methods: (a) gas adsorption method (N2 adsorption), (b) air permeability method and (c) microscopic method. The area values are compared. In the gas adsorption method, the effect of degassing temperature on the surface area of solid was studied. In the permeability method the porosity range over which the specific surface area remains constant was also determined. 相似文献
6.
Anindita Bhattacharjee† 《Molecular physics》2013,111(15):2485-2495
We show that the de-excitation to different vibrational levels of the ground state in NaH molecule can be controlled by using two delayed ultrashort pulses (4 fs Gaussian). A vibrational wave packet generated on the excited A1Σ+ state by the first pulse is de-excited back to the ground state by a second pulse after a time delay. The cross-section for de-excitation of the wave packet to different vibrational levels of the ground electronic state can be controlled by controlling the delay time between the two pulses as well as by choosing a pulse duration much shorter than the vibrational period of the molecule, such that the de-excited wave packet remains localized in the Franck–Condon region of a particular vibrational level of the ground state. Hence, the de-excitation to a particular vibrational level can be enhanced by suppressing that in others. In spite of the large bandwidth of the pulse which includes nine vibrational levels of the upper state and five vibrational levels of the ground state, one can selectively de-excite the molecule to any one or two vibrational levels of the ground state by carefully choosing the delay time between the pulses and the pulse duration. We are designing the wave packet in the ground state by two short pulses and selectively distributing the population in one or two levels at various values of the delay time. In light molecules having small vibrational period, this selectivity in de-excitation to one or two vibrational levels in the ground state can be achieved only by using ultrashort (4 fs) pulses in the presence of which the localization of the wave packet in the Franck–Condon region of the vibrational levels are particularly possible. It has been shown that the de-excitation cross-section to a particular vibrational level oscillates with delay between the pulses which can be realized as a time-dependent quantum gate. 相似文献
7.
K2Ca2(SO4)3 microcrystalline pure, doped with Eu, Tb and co-doped with Eu, Tb was prepared by solid-state diffusion method. Nanoparticles of these phosphors were also prepared by the chemical co-precipitation method. The formation of the compounds was confirmed by XRD. The particle size was calculated by broadening of the XRD peaks using Scherrer's formula. The particle size of nanocrystalline powder material was approximately found to be around 20 nm. Thermoluminescence and photoluminescence were studied to see the effect of co-doping and particle size. Tb3+ co-doping decreases the intensity in the Eu2+ doped phosphor due to the energy transfer and multiple de-excitations through various radiative and non-radiative processes. The sensitivity of K2Ca2(SO4)3:Eu,Tb microcrystalline phosphor was around 15 times more than LiF-TLD 100 and 7 times more than CaSO4:Dy. A high temperature peak (615 K) was observed in case of the nanoparticles, which was attributed to a particle size induced phase transition. This was confirmed by differential scanning calormetry measurements. The decrease in the sensitivity in case of nanoparticles is attributed to the particle size effect i.e. volume to surface ratio. Theoretical analysis of the glow curves was done by glow curve convolution deconvolution method to calculate trapping parameters of various peaks. 相似文献
8.
Hermann G. Burchard † 《Applicable analysis》2013,92(4):309-319
Let SM k be the Polynominal splines of degree n-1, and with K segments. If f∈ C n [a,b],then the distance in the Lp-norm form(0< p ≦ ∞)of from S M k is boundedby M/K n , with a much smaller M than in similar estimates for other processes of approximation. 相似文献
9.
We present a unified framework for constructing the globally convergent algorithms for a broad class of multidimensional coefficient inverse problems arising in natural science and industry. Based on the convexification approach, the unified framework substantiates the numerical solution of the corresponding problem of nonconvex optimization. A globally convergent iterative algorithm for an inverse problem of diffuse optical mammography is constructed. It utilizes the contraction property of a nonlinear operator resulting from applying the convexification approach. The effectiveness of this algorithm is demonstrated in computational experiments. 相似文献
10.
This article studies the existence of viable solutions to the Cauchy problem u′ ∈ ? (t , u) for a.e. t∈ [0,1], u (0)=x 0 ∈ K (a closed subset of R N ) where the nonlinearity ? satisfies a Wintner-type growth condition. 相似文献