检索结果-南通市图书馆

Catalytic activity of manganese oxide supported on alumina in the synthesis of quinoxalines

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2013年第4期7卷 415-421页

作者： Rekha m. Kathyayini H nagaraju n Catalysis Research Laboratory St Joseph's College Post Graduate and Research Centre Bangalore 560027 India Centre for emerging Technologies Global Campus Jain University Bangalore 562112 India

Two catalysts, alumina and manganese oxide supported on alumina, have been prepared by calcination and precipitation-impregnation methods, respectively. The catalysts are characterised by the following techniques： Brunner-emmett-Teller-n2 adsorption-desorption for sur- face area, temperature programmed desorption of nH3 and n-butyl amine back titration methods for surface acidity, powder X-ray diffraction for textural properties, and Fourier transform infrared spectroscopy for the anionic radicals. The catalytic activity has been determined under heterogeneous conditions in the condensation reaction between o-phenylenediamine and benzil. The product purity is checked by thin-layer chromatography and melting point. The products are also analysed by LC-mS and 1H-nmR techniques. The yields of the products have been found to be good and catalysts exhibited excellent recyclability. The effect of changing the reaction para- meters such as temperature, reaction time, amount of the catalyst, nature of solvent and molar ratio of reactants on the yield of the product has been studied. The surface acidity of the catalysts plays an important role in activating the reaction.

关键词： alumina manganese oxide deposited onalumina quinoxaline synthesis

magnetic and electronic properties of double perovskite Sr2CrmoO6 for spintronic applications: insights from first-principles and monte Carlo approaches

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第12期76卷 168-175页

作者： H Kerrai n Zaim m Kerouad A Zaim Laboratoire de Physique des matériaux et modélisation des Systèmes (LP2mS) Unité Associée au CNRST-URAC: 08 Moulay Ismail University Faculty of Sciences

in this work,we studied the electronic and magnetic properties of the double perovskite Sr2CrmoO6using ab initio calculations with generalized gradient approximation（GGA） and monte Carlo（mC） *** compound has two magnetic sublattices:one occupied by mo5+with spin（S=1/2） and the other by Cr3+with spin（σ=3/2） The results showed halfmetallic behavior with a total magnetic moment of 2.0 μB. Using monte Carlo simulations,we investigated the phase transitions and observed interesting phenomena such as a critical endpoint and both second-order and first-order phase ***,the results revealed compensation points for specific values of the crystal field.

关键词： DFT magnetic properties monte Carlo simulation spintronic applications

Trace-Rare-Gas Optical emission Spectroscopy of nitrogen Plasma Generated at a Frequency of 13.56 mHz

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2011年第2期13卷 208-212页

作者： n.U.REHmAn F.U.KHAn S.nASEER G.mURTAZA S.S.HUSSAin i.AHmad m.ZAKAULLAH Department of Physics COMSATS Institute of Information Technology Department of Physics Gomal University Department of Physics Peshawar University Department of Physics Quaid-i-Azam University

Optical emission spectroscopic measurem.nt of trace rare gas is carried out to determine the density of nitrogen （n） atom, in a nitrogen plasma, as a function of filling pressure and RF power applied. 2% of argon, used as an actinometer, is mixed with nitrogen. in order to normalize the changes in the excitation cross section and electron energy distribution function at different operational conditions, the Ar-i emission line at 419.83 nm is used, which is of nearly the same excitation efficiency coefficient as that of the nitrogen emission line at 493.51 nm. it is observed that the emission intensity of the selected argon and atomic nitrogen lines increases with both pressure and RF power, as does the nitrogen atomic density.

关键词： optical actinometry n atomic density EEDF RF plasma

modulation instability of Low Frequency Whistler Waves

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1997年第4期14卷 287-290页

作者： WAnG De-yu m.Raadu n.Brenning Purple mountain Observatory Chinese Academy of SciencesNanjing 210008 Alfen Laboratory Royal Institute of TechnologyStockholmSweden

A self-focusing modulation instability of whistler wave has been investigated in the frequency region of ω_(ci)<ω<<ω_(ce).it is found that the ion term contribution should be taken into *** results show that the ne... 详细信息

A self-focusing modulation instability of whistler wave has been investigated in the frequency region of ω_(ci)it is found that the ion term contribution should be taken into *** results show that the necessary condition of instability depends on the pitch angle of perturbation wave.

关键词： wave. perturbation wave

A model for the chain-to-plane charge transfer in YBa2Cu3O6+x

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第11期21卷 450-454页

作者： V.m.matic n.Dj.Lazarov m.milic Laboratory of Theoretical Physics Institute of Nuclear Sciences “Vinca”Belgrade University

A model for the chain-to-plane charge transfer is proposed to account for the two plateaus,at 60 K and at 90 K,of the Tc(x) characteristics of the YBa2Cu3O6+x high-Tc *** is assumed that the number of holes transferred from a CuO chain of length l to two nearby CuO2 sheets is proportional to l(that is,to the number of oxygen atoms in the chain),if the chain length is greater than,or equal to,a certain critical chain length,lcr,that is required to trigger the charge transfer *** holes are assumed to have been transferred from chains of length l更多还原AbstractFilter('ChDivSummary', 'ChDivSummarymore', 'ChDivSummaryReset');

关键词： YBCO oxygen ordering critical temperature doping

Li(2p←2s)+na(3s)pressure broadening in the far-wing and line-core profiles

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第7期31卷 247-254页

作者： F Talbi n Lamoudi L Reggami m T Bouazza K Alioua m Bouledroua Physics Department Badji Mokhtar UniversityB.P.12Annaba 23000Algeria Laboratoire de Physique des Rayonnem.nts Badji Mokhtar UniversityB.P.12Annaba 23000Algeria Laboratoire d’Etude des Surfaces et interfaces de la matiere Solide(LESimS) Badji Mokhtar UniversityB.P.12 Annaba 23000Algeria Laboratoire LamA Laboratoire des Materiaux Avances(LAMA)Badji Mokhtar UniversityB.P.12 Annaba 23000Algeria Laboratoire de Physique de la matiere et du Rayonnem.nt LPmR Universite Cherif MessaidiaB.P.1553Souk-Ahras 41000Algeria

This work reports pressure-broadening line-wing and line-core of the lithium Li(2p←2s)resonance line perturbed by ground sodium na(3s)*** far-wing regions,the calculations are performed quantum-mechanically and are intended to examine the photoabsorption coefficients at diverse *** results show the existence of three satellites,in the blue wing near the wavelengths 470 nm and in the red wing around 862 nm and 1070 *** the line-core region,by adopting the simplified Baranger model,the line-width and line-shift rates are determined,and their variation law with temperature is *** published data were found to compare these results with.

关键词： pressure broadening line-core broadening far-wing spectra photoabsorption

Performance evaluation of DHRR-RiS based HP design using machine learning algorithms

在线全文

学校读者我要写书评

暂无评论

intelligent and Converged networks 2023年第3期4卷 237-260页

作者： Girish Kumar n G Sree Ranga Raju m n the Department of Electronics and Telecommunication Engineering Bangalore Institute of TechnologyVisvesvaraya Technological UniversityBangalore 560004India the Department of Electronics and Communication Engineering Bangalore Institute of TechnologyVisvesvaraya Technological UniversityBangalore 560004India

Reconfigurable intelligent Surfaces(RiS)have emerged as a promising technology for improving the reliability of massive mimO communication ***,conventional RiS suffer from poor Spectral Efficiency(SE)and high energy consumption,leading to complex Hybrid Precoding(HP)*** address these issues,we propose a new low-complexity HP model,named Dynamic Hybrid Relay Reflecting RiS based Hybrid Precoding(DHRR-RiS-HP).Our approach combines active and passive elem.nts to cancel out the downsides of both conventional *** first design a DHRR-RiS and optimize the pilot and Channel State information(CSi)estimation using an adaptive threshold method and adaptive Back Propagation neural network(ABPnn)algorithm,respectively,to reduce the Bit Error Rate(BER)and energy *** optimize the data stream,we cluster them into private and public streams using Enhanced Fuzzy C-means(EFCm)algorithm,and schedule them based on priority and emergency *** maximize the sum rate and SE,we perform digital precoder optimization at the Base Station(BS)side using Deep Deterministic Policy Gradient(DDPG)algorithm and analog precoder optimization at the DHRR-RiS using Fire Hawk Optimization(FHO)*** implem.nt our proposed work using mATLAB R2020a and compare it with existing works using several validation *** results show that our proposed work outperforms existing works in terms of SE,Weighted Sum Rate(WSR),and BER.

关键词： Reconfigurable intelligent Surfaces(RiS) Dynamic Hybrid Relay Reflecting(DHRR)-RiS multi User multiple input multiple Output(mU-mimO) hybrid precoder machine learning and deep learning algorithms channel state estimation

Dielectric Behavior of modified Cellulose

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 1999年第2期15卷 164-168页

作者： El-Henawii, S.A. Saad, S.m. El-Anwar, i.m. Faculty of Science Helwan University Egypt Chemistry Department Faculty of Science Al-Azhar University Egypt Physical Chemistry Unit of the N.R.C Egypt

The dielectric constants and the dielectric loss, as well as the activation energy of dielectric relaxation of silylated cellulose were measured within the frequency range 10**5 to 10**7 Hz and the temperature range from 10 to 50 degree C. The test samples were activated cellulose with ethylene diamine, with sodium hydroxide and inactivated cellulose before and after silylation. The measurem.nts were carried out using a multi-deka-meter. Cellulose molecules are more activated by treatment with ethylene diamine than with sodium hydroxide. Generally, silylation causes a marked decrease of the dielectric constant and dielectric loss, meanwhile the silylated samples are affected with the pretreatment of linters with sodium hydroxide and ethylene diamine. (Edited author abstract) 28 Refs.

关键词： Cellulose

nuclear Level Density with non-zero Angular momentum

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2006年第3X期46卷 514-520页

作者： A.n. Behkami m. Gholami m. Kildir m. Soltani Physics Department Mahabad Islamic Azad University Mahabad Iran Chemistry Department Middle East Technical University Ankara Turkey physics Department Shiraz University Shiraz Iran

The statistical properties of interacting fermions have been studied for various angular momentum with the inclusion of pairing interaction. The dependence of the critical temperature on angular momentum for several nuclei, have been studied. The yrast energy as a function of angular momentum for 28Si and 24 mg nuclei have been calculated up to 60.0 meV of excitation energy. The computed limiting angular momenta are compared with the experimental results for ^26Al produced by ^12C＋ 14n reaction. The relevant nuclear level densities for non-zero angular momentum have been computed for ^44Ti and ^136 Ba nuclei. The results are compared with their corresponding values obtained from the approximate formulas.

关键词： nuclear structure statistical properties of paired nucleons