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1.
The subject of spectral distribution methods where one derives and applies the locally smoothed forms of observables in nuclei
is briefly reviewed. It is well understood that the local forms (with respect to energy) of the level density function, expectation
values and strength densities are Gaussian, linear (or ratio of Gaussians) and a bivariate Gaussian respectively. To accomodate
symmetries in the above forms, one has to deal with multivariate distributions in general; for example the angular-momentum
(J) decomposition leads to a bivariate Gaussian form for the level density. These results extend to indefinitely large spaces
by method of partitioning and they generate convolution forms. The origin of these remarkable spectral properties is discussed
and shell model examples are given to substantiate their applicability to nuclear systems. Spectral distribution theory is
a practical, usable theory because the smoothed forms are defined in terms of traces of low particle-rank operators, and the
trace information propagates. Finally we discuss the application of the spectral methods for a wide range of nuclear problems;
these include binding energies, orbit occupancies, electromagnetic andβ-decay sum rule quantities, analysis of operators, symmetry breaking, numerical level densities, and determination of bounds
on time-reversal non-invariant part of nucleon-nucleon interaction. 相似文献
2.
Rao DP Sivakumar SV Mandal S Kota S Ramaprasad BS 《Journal of chromatography. A》2005,1069(1):141-151
The separation of propylene-propane mixture is an energy intensive operation commercially practiced using cryogenic distillation. The separation by pressure swing adsorption has been studied as an alternative. A fixed-bed pressure swing adsorption yields the heavy component as a pure product. The product recovery and the productivity are not high. In a moving-bed process, because of the counter-current solid-gas contact, the separation achieved is similar to that of the fractionation by distillation. Although the moving-bed operation offers the upper limit for the performance of a cyclic adsorptive process, due to mechanical complexities in the handling of solids the 'simulated' moving-bed is preferred. By moving the inlet and outlet ports of streams located along the length of the bed, a moving-bed process can be realized in a fixed bed. We describe here a 'moving-port' system which permits injection or withdrawal of the fluid along the axial direction in a fixed bed. A fixed bed embedded with the moving-port systems emulates a simulated moving-bed adsorber. The proposed adsorber can fractionate a binary gas mixture into two product streams with high purities. It is similar to the Sorbex process of UOP but does not have the eluent as an additional separating agent. A parametric study indicates that high purity products and a higher productivity by an order of magnitude can be achieved with simulated moving-beds compared to the fixed beds. 相似文献
3.
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5.
Jun-Ichiro Makiura Takuma Higo Yutaro Kurosawa Kota Murakami Shuhei Ogo Hideaki Tsuneki Yasushi Hashimoto Yasushi Sato Yasushi Sekine 《Chemical science》2021,12(6):2108
Efficient activation of CO2 at low temperature was achieved by reverse water–gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu–In structured oxide, even at lower temperatures. Results show that a novel Cu–In2O3 structured oxide can show a remarkably higher CO2 splitting rate than ever reported. Various analyses revealed that RWGS-CL on Cu–In2O3 is derived from redox between Cu–In2O3 and Cu–In alloy. Key factors for high CO2 splitting rate were fast migration of oxide ions in the alloy and the preferential oxidation of the interface of alloy–In2O3 in the bulk of the particles. The findings reported herein can open up new avenues to achieve effective CO2 conversion at lower temperatures.Efficient activation of CO2 at low temperature was achieved by reverse water–gas shift via chemical looping (RWGS-CL) by virtue of fast oxygen ion migration in a Cu–In structured oxide, even at lower temperatures. 相似文献
6.
An optical sensor using a quartz core microcantilever was fabricated by etching clad layer from optical fiber. The temperature dependence of the resonance frequency of this sensor was measured in atmosphere and water. The temperature coefficient of the resonance frequency in water was 1.3×10−3/°C, which was about one order larger than that (2.3×10−4/°C) in atmosphere. This was caused by increase of additional mass due to temperature dependence of the viscosity of water, while, the increase of the resonance frequency in atmosphere was caused by temperature dependence of Young’s modulus of the quartz core. These results were evaluated theoretically using a “string-of-beads” model. 相似文献
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8.
Embedded random matrix ensembles are generic models for describing statistical properties of finite isolated interacting quantum many-particle systems. For the simplest spinless fermion (or boson) systems, with say m fermions (or bosons) in N single particle states and interacting via k-body interactions, we have EGUE(k) [embedded GUE of k-body interactions] with GUE embedding and the embedding algebra is U(N). A finite quantum system, induced by a transition operator, makes transitions from its states to the states of the same system or to those of another system. Examples are electromagnetic transitions (then the initial and final systems are same), nuclear beta and double beta decay (then the initial and final systems are different), particle addition to or removal from a given system and so on. Towards developing a complete statistical theory for transition strength densities (transition strengths multiplied by the density of states at the initial and final energies), we have derived formulas for the lower order bivariate moments of the strength densities generated by a variety of transition operators. Firstly, for a spinless fermion system, using EGUE(k) representation for a Hamiltonian that is k-body and an independent EGUE(t) representation for a transition operator that is t-body and employing the embedding U(N) algebra, finite-N formulas for moments up to order four are derived, for the first time, for the transition strength densities. Secondly, formulas for the moments up to order four are also derived for systems with two types of spinless fermions and a transition operator similar to beta decay and neutrinoless beta decay operators. In addition, moments formulas are also derived for a transition operator that removes k0 number of particles from a system of m spinless fermions. In the dilute limit, these formulas are shown to reduce to those for the EGOE version derived using the asymptotic limit theory of Mon and French (1975). Numerical results obtained using the exact formulas for two-body (k=2) Hamiltonians (in some examples for k=3 and 4) and the asymptotic formulas clearly establish that in general the smoothed (with respect to energy) form of the bivariate transition strength densities take bivariate Gaussian form for isolated finite quantum systems. Extensions of these results to bosonic systems and EGUE ensembles with further symmetries are discussed. 相似文献
9.
Minami Odagi Kota Furukori Tatsuya Watanabe Prof. Dr. Kazuo Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16740-16745
Highly enantioselective catalytic oxidation of 1‐tetralone‐derived β‐keto esters was achieved by using a guanidine–urea bifunctional organocatalyst in the presence of cumene hydroperoxide (CHP), a safe, commercially available oxidant. The α‐hydroxylation products were obtained in 99 % yield with up to 95 % enantiomeric excess (ee). The present oxidation was successfully applied to synthesize a key intermediate of the anti‐cancer agent daunorubicin ( 2 ). 相似文献
10.
K. Pramoda Kota Moses Mohd. Ikram K. Vasu A. Govindaraj C. N. R. Rao 《Journal of Cluster Science》2014,25(1):173-188
Single-walled nanohorns (SWNHs) have been prepared by sub-merged arc discharge of graphite electrodes in liquid nitrogen. The samples were examined by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Nitrogen and boron doped SWNHs have been prepared by the sub-merged arc discharge method using melamine and elemental boron as precursors. Intensification of Raman D-band and stiffening of G-band has been observed in the doped samples. The electrical resistance of the SWNHs varies in opposite directions with nitrogen and boron doping. Functionalization of SWNHs through amidation has been carried out for solubilizing them in non-polar solvents. Water-soluble SWNHs have been produced by acid treatment and non-covalent functionalization with a coronene salt. SWNHs have been decorated with nanoparticles of Au, Ag and Pt. Interaction of electron donor (tetrathiafulvalene, TTF) and acceptor molecules (tetracyanoethylene, TCNE) with SWNHs has been investigated by Raman spectroscopy. Progressive softening and stiffening of Raman G-band has been observed respectively with increase in the concentration of TTF and TCNE. 相似文献