Synthesis of 1,4-dithiins from pentathiepins

Fused aromatic and heterocyclic 1,2,3,4,5-pentathiepins react with triphenylphosphine and alkynes bearing electron-withdrawing groups to give the corresponding 1,4-dithiins in high yields. Unsymmetrical alkynes add regioselectively to afford products in agreement with the electron distribution in a proposed reaction intermediate. A mechanism for these reactions is proposed.     

相对论重离子碰撞的温度涨落与热容

使用LUCIAE3.0模型模拟了SPS能区Pb+Pb和C+C在不同能量(E_lab=20—200A GeV)和不同中心度下的重离子碰撞.并通过逐个事件的粒子温度涨落提取出了相应粒子的热容,发现对于同一碰撞系统,单位发射粒子的热容随碰撞能量的升高而下降直至饱和,随着碰撞参数b的增大而减小,而且发现单位发射粒子的热容具有随粒子质量的变大而变大的关系.同时还发现不同碰撞系统中同一种粒子具有相同的单位发射粒子热容,并给出了相应的解释.     

158A GeV的相对论重离子碰撞的强子快度分布及温度拟合

针对最近NA49在158A GeV的实验(C+C,Si+Si,Pb+Pb)数据,应用LUCIAE3.0模型进行模拟,得到了强子的快度分布和横向动量分布,并与实验数据进行比较,发现基本与实验数据相吻合。并对横向动量分布进行温度拟合,给出了和实验数据吻合很好的结果,但是对于重系统或重强子LUCIAE3.0给出的结果与实验符合相对较差.     

Reactions of Podophyllotoxin with DDQ

Introduction 2, 3-Dichloro-5, 6-dicyanobenzoquinone (DDQ) can react with lignans of the mono- arylidene-butyrolactone1, aryltetralin2, dibenzylbutane3 and aryltetralin-butyrolactone4,5 series. We have studied the reactions of this reagent with podophyllotoxin 1, which is a well-known natural product on account of its long history of use in folk medicine and the biological activity of its many derivatives6. In particular, derivatives of 4-demethyl epipodophyllotoxin are used in cancer chemo…     

高能重离子碰撞中正负荷电粒子比单事例起伏研究

用强子和弦级联模型,JPCIAE及相应的Monte Carlo事例产生器,研究相对论性核–核碰撞中有限快度区间内正负荷电粒子比单事例起伏与能量、中心度、共振态衰变及快度间隔的关系.JPCIAE模型能够较好地符合CERN/SPS能区Pb+Pb碰撞的实验结果.本文还用此模型预言了RHIC能区Au+Au碰撞和ALICE能区Pb+Pb碰撞中的正负荷电粒子比单事例起伏.可以看出碰撞能量、中心度、共振态衰变及快度间隔对正负荷电粒子比单事例起伏的影响都不大.     

Theoretical Study of Hydrated Cd~（2＋） Interactions with Guanine

Theoretical study was performed to investigate how the hydration of cadmium ca-tion influences the structure and properties of guanine.The aqueous environment was simulated by both explicit solvent(1-5 water molecules) model and implicit solvent model.For complexes in which Cd2+ attached to the N(7) and O(6) sites of guanine,energy analysis together with the Natural Bonding Orbital(NBO) analysis were performed to elucidate the bonding characteristics in detail.The most stable structures are penta-coordinate complexes without aqua ligand located at the guanine site.Higher number of water ligands corresponds to higher stabilization energies.Average bonding energies of G-Cd increase with the number of water molecules.Bonding energies of water ligands depend on its position in the complexes.The charge distribution of guanine changed with increasing the number of water ligands,which may also influence the base-pairing pattern of guanine.There is positive charge transfer from guanine to aqua ligand as the number of the hydration waters increases.IEFPCM optimization has results comparable to the [CdG(H2O)5]2+ structure 5a.     

Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

以水溶性聚合物为保护剂,采用化学还原法制备了银纳米粒子,分别利用透射电子显微镜、紫外可见光谱、同步光散射光谱等手段对其进行了表征,并探索了制备银纳米粒子的最佳实验条件。通过将银纳米粒子-聚合物溶液进行脱水,得到含有银纳米粒子的固态聚合物膜。将固态聚合物膜重新溶解于水,其水溶液的紫外可见光谱与脱水前的溶液进行了比较,发现两者性质并无明显差异。因此,将银纳米粒子分散固定在聚合物膜中是一种崭新而有效的银纳米粒子制备和存储方法。     

Chemical-Deposited Biaxially Textured Oxides YBCO,Y2O3 and LZO as Functional Layers for 2G HTSC Tapes

Moscow University Chemistry Bulletin - Abstract—2G HTSC tapes YBCO/LZO/Ni-5W and YBCO/Y2O3/LZO/Ni-5W with the minimum number of layers are obtained. Heteroepitaxial structures (layers...     

Electrochemical corrosion of thin ferromagnetic Fe—N films in neutral solution

A model experiment was conducted in order to determine an interplay between inherent strains and electrochemical corrosion rate in nitrogen-doped iron thin films. 150 and 300 nm thick films, used in the experiment, were obtained by means of DC magnetron sputtering. In order to study the influence of substrate on inherent strains in metal, these films were deposited onto flexible polymer and rigid glass substrates. It was found, that the rigidity of the substrate increased the corrosion rate of thin iron films in a neutral electrolytic solution. It was proven using X-ray diffraction, that the greater rigidity was, the stronger were the internal strains within the films. That effect was especially pronounced in thinner films, where the increase in the rate of dissolution was accompanied by a localization of corrosion. Characteristics of electrochemical processes were measured using a three-electrode cell. The comparison of the films free surface energy was performed by measuring water contact angle.