The symmetric and antisymmetric superexchange interactions in spin-Peierls system

The influences of Dzyaloshinskii Moriya （DM） interaction and Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczos numerical method. The ground state of the spin-Peierls system is still dimerized phase when both of the DM and the KSEA interactions have the same value with Heisenberg interaction. It is found that the KSEA interaction and uniform DM interaction are always against systemic dimerization, but the staggered DM interaction acts in favour of dimerization. Furthermore, the influences of the DM and the KSEA interactions are also studied in terms of the ground state index rate and the energy gap index rate of the dimerized Heisenberg system. The results show that the DM interaction makes the index rates larger, while the KSEA interaction makes them smaller.     

Improving nucleation in the fabrication of high-quality 3D macro-porous copper film through the surface-modification of a polystyrene colloid-assembled template

A new approach is developed to the fabrication of high-quality three-dimensional macro-porous copper films. A highly-ordered macroporous copper film is successfully produced on a polystyrene sphere (PS) template that has been modified by sodium dodecyl sulfate (SDS). It is shown that this procedure can change a hydrophobic surface of PS template into a hydrophilic surface. The present study is devoted to the influence of the electrolyte solution transport on the nucleation process. It is demonstrated that the permeability of the electrolyte solution in the nanochannels of the PS template plays an important role in the chemical electrodeposition of high-quality macroporous copper film. The permeability is drastically enhanced in our experiment through the surface modification of the PS templates. The method could be used to homogeneously produce a large number of nucleations on a substrate, which is a key factor for the fabrication of the high-quality macroporous copper film.     

溶解过程的热效应

溶解热是质-剂微粒间作用(释热)与拆开原先溶质微粒间作用(吸热)、部分溶剂微粒间作用(吸热),在能量方面的代数和,以1 mol溶质溶于大量溶剂(通常是水)计量热效应(kJ/mol)为准。强调“大量溶剂”是因为热效应随溶剂量(在一定范围内)而改变,把1 mol H2SO4、1 mol HCl在水中溶解热和溶剂量的关系列于下表:由H2SO4溶解热前3竖行知:往n(H2SO4)/n(H2O)=1.0/0.5=2.0溶液中加0.5 mol H2O时释热量为:-27.82 kJ/mol-(-15.73 kJ/mol)=-12.09 kJ/mol;若再加0.5 mol H2O,释热量为:-35.90 kJ/mol-(-27.82 kJ/mol)=-8.08 kJ/mol。由HCl(g)溶解热…     

柠檬酸钠对氢氧化镁铝微粒乳化作用的影响

氢氧化镁铝;微粒乳化作用;液体石蜡;柠檬酸钠     

Initial Processes of Sulfur Adsorption on Si（100） Surface

The adsorption of one monolayer S atoms on ideal Si（100） surface is studied by using the self-consistent tight binding linear muffon-tin orbital method. Energies of adsorption systems ors atoms on different sites are calculated. It is found that the adsorbed S atoms are more favorable on B1 site （bridge site） with a distance 0.131 nm above the Si surface. The .S, Si mixed layer might exist at S/Si（100） interface. The layer projected density of states are calculated and compared with that of the clean surface. The charge transfers are also investigated.     

Theoretical Study on the Intermolecular Interactions of Tetrazole Dimers

1 INTRODUCTION Tetrazole and its derivatives are widely applied in the fields of agriculture, biology, chemistry, phar- macology and photographic technology, and they play significant roles in the science and technology as well as national defence[1]. In the past, the res- earches were focused on the molecular geometries, electronic structures, IR, thermodynamic properties, tautomerization, pyrogenation and sensitivity of tetrazole compounds[1～5]. However, study of tetra- zole dimers ha…     

Synthesis and Crystal Structure of the Derivative of Hydroquinone from Mannich Reaction

1 INTRODUCTION Mannich reaction plays an important role in theconstruction of a large variety of nitrogen-containingmolecules, for instance, some pharmaceuticals andnatural products[1, . In practice, phenols and naph- 2]thanols can serve as the substrate of Mannich reac-tion to obtain aminomethylate by the treatment withformaldehyde and amines or nitrogen heterocycliccompounds[3～5]. We report herein the synthesis andcrystal structure of a new nitrogencontaining co…     

Purification of Pseudomonas sp. Lipase by Continuous Elution Electrophoresis Based on Pb^2＋ Precipitation Method

A Pb^2 precipitation method was designed to get rid of the impure proteins in a lipase. The results show that it was a simple way in the primary treatment of the crude samples and about 20% impure proteins were removed in the precipitation step. Further, continuous elution electrophoresis was also applied as a preparative technique for attaining the highly pure lipase. During the continuous elution electrophoresis, the enzyme was eluted as a single peak and 5.7-fold purification was achieved in a yield of 54.3%. The two steps finally yielded an electrophoretically homogeneous enzyme.     

Mass Spectrometry of 2a, 4-Disubstituted 5-Benzoyl-2a, 3,4,5-tetrahydro-2-phenoxy-azeto [ 1,2-a ] [1,5 ] benzodiazepin - 1 （2H）-ones Under Electron Impact Ionization Conditions

The mass spectrometric fragmentation of 2a, 4-disubstituted 5-benzoyl-2a, 3,4, 5-tetrahydro-2-phenoxy-azeto[1,2-α] [ 1,5 ] benzodiazepin-I (2H)-ones has been investigated by means of mass-analyzed ion kinetic energy spectrometry under electron impact ionization conditions. All compounds tend to lose different moieties, such as phenoxy, phenoxy and H, and phenoxyketene. Both [ M^ - PhO ] and [ M^ - PhOH ] ions could further lose CO, and the [ M^ - PhOCH = C = O] ions could lose propene or styrene, PhCON, PhCOHN, and other fragments.     

甲基纤维素(MC)疏水作用的电化学研究

应用电化学循环伏安法, 以电活性小分子亚甲基蓝(MB)为探针, 研究了不同温度下修饰在玻碳电极表面的甲基纤维素(MC)凝胶的疏水性. 研究发现, 在45～70 ℃温度范围内, MB在MC凝胶修饰电极上的式电位E⁰⁽较相应的裸电极均正移, 氧化峰电流i_pa和还原峰电流i_pc分别较相应裸电极增大, 且随温度升高而增大. 这些结果表明MC分子之间发生了疏水相互作用, 且随温度的升高, 疏水作用增强. 此外, 在上述温度下, MC凝胶修饰电极上峰电流的比值i_pc/i_pa均小于1, 为0.70, 且没有观察到MB单独的吸附峰, 因此MB分子在凝胶修饰电极上发生了弱吸附. 本文研究显示电化学方法是研究该类多糖凝胶机理的一个补充手段.