Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives

Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated. Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals. The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm² only increases the grain size from 60 to 62 nm.     

聚醚型多嵌段共聚物软链段结晶特性的研究

本文使用虹外光谱及膨胀计等方法,对聚四亚甲基醚二醇类多嵌段共聚物的软链段结晶性进行了研究。在聚醚-聚酯多嵌段共聚物中(PTMEG>60％),其软链段结晶的熔点和结晶速率均随PTMEG含量减少而下降。而在聚醚-聚脲胺酯多嵌段共聚物中,由于N—H和C—O—C之间氢键的作用,即使在低温下,其软链段也难于结晶。此外,高倍拉伸会提高上述二类多嵌段共聚物中软链段结晶的熔点和结晶速率。     

The Crystalline Changes of Starch from Rhizoma Dioscorea by Acid Hydrolysis

Dioscoreae (Chinese name Shanyao), the rhizome of various species of genus Dioscorea opposita Thunb.(Dioscoreaceae), has been used as an important invigorant in traditional Chinese medicine (TCM) for many years1. Starch, the most abundant carbohydrate in …     

The first mu3-oxalato-bridged copper complex with tridentate Schiff base ligand N-ethyl-N'-salicylidene-1,2-diaminoethane: synthesis,structure, and magnetic properties

The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms.     

正丁烷氧化制顺酐流化床催化剂的性能

 考察了前驱体制备过程中水合肼／五氧化二钒摩尔比（以下简记\r\n为n（N2H4）／n（V2O5））对催化剂性能的影响．由较高的n（N2H4）\r\n／n（V2O5）比制得的催化剂，其（VO）2P2O7相含量较多，正丁烷转化\r\n率较高．随着n（N2H4）／n（V2O5）比的减小，δ－VOPO4相的含量逐\r\n渐增多，正丁烷转化率随之升高；而顺酐选择性开始时升高，达到最大\r\n值后逐渐降低．在n（N2H4）／n（V2O5）＝0．34时制备的催化剂最佳\r\n，在丁烷浓度为4．0％、空速为500h－1及反应温度为420℃的反应条件\r\n下，顺酐收率可达49．74％．本文中细粒床催化剂有较大的操作弹性．     

Single‐Crystalline and Near‐Monodispersed NaMF3 (M=Mn,Co, Ni,Mg) and LiMAlF6 (M=Ca,Sr) Nanocrystals from Cothermolysis of Multiple Trifluoroacetates in Solution

We report the synthesis of single‐crystalline and near‐monodispersed NaMF₃ (M=Mn, Co, Ni, Mg), LiMAlF₆ (M=Ca, Sr), and NaMgF₃:Yb,Er nanocrystals (quasisquare nanoplates, nanorods, and nanopolygons) by the cothermolysis of multiple trifluoroacetates in hot combined organic solvents (oleic acid, oleylamine, and 1‐octadecene). The nanocrystals were characterized by XRD, TEM, superconductive quantum interference device (SQUID), and upconversion luminescence spectroscopy. By regulating the polarity of the dispersant, the NaMF₃ (M=Mn, Co, Ni) nanoplates were partially aligned to form nanoarrays on copper TEM grids. The sizes of the NaMF₃ nanocrystals were easily tuned by the use of proper synthetic conditions such as reaction temperature and time and solvent composition. On the basis of a series of experiments in which the reaction conditions were varied, together with GC–MS and FTIR analysis, the reaction pathways for the formation of these nanocrystals from trifluoroacetate precursors were proposed. The magnetic measurements showed that the differently sized NaMnF₃ square plates displayed interesting weak ferromagnetic behavior on the nanometer scale. The strong red upconversion luminescence emitted from the NaMgF₃:Yb,Er nanorods under 980‐nm near‐IR laser excitation suggests that NaMgF₃ may be a good candidate host material for red upconversion luminescence.     

Effects of antimony on the surface tension of molten silicon

The effect of antimony concentration (C(Sb)/mass%) on the surface tension of molten silicon has been determined with the sessile drop method in the temperature range from 1693 to 1773 K and in the range of the oxygen partial pressure, Po(2), in an Ar atmosphere from 10(-23) to 10(-21) MPa. The results show that the surface tension of molten silicon decreases with increasing Sb concentration in the range of C(Sb)<0.9 mass%, which indicates positive adsorption of Sb in molten silicon and can be fairly described with the Szyszkowski's equation. The maximum decrease rate of surface tension is about 65 mN m(-1) (mass% C(Sb))(-1), and the temperature coefficient of surface tension, (partial differential sigma/ partial differential T)C(Sb), increases with increasing C(Sb). The evaporation of the systems was only observed between the melting points of antimony (904 K) and silicon (1683 K), and the surface tension presents no dependence on measuring time above the melting point of silicon.     

新型化合物[Ni(en)3]2[Ni(en)2(H2O)2][As6V15O42]·4H2O晶体的水热合成与表征

金属氧酸盐因其在医药临床、工业催化、功能材料等方面的广泛应用而引起人们的关注[1～6], 其中, 有关钒化学的研究一直很活跃, 钒具有与钼、钨明显不同的结构特性, 钒可以采取VO4, VO5和VO6方式配位, 同时, 钒的价态可以是+3, +4和+5价. 由于钒可采取多种配位方式及多种价态, 与钼酸盐和钨酸盐相比, 钒酸盐更具有结构柔顺性, 同时易形成低价或混合价态物种.在以往的文献中, 有关P-V-O体系多金属氧酸盐的水热合成的研究已有大量的报道[7], 在常规溶液合成中, 人们已对As-V-O体系进行了相对深入的研究, 而有关水热合成的研究报道却很少, 已见报道的砷钒化合物有K6*6H2O[8,9], 4-[10], 6-[11](X=SO2-3, SO2-4, H2O). 为了探究水热条件下As-V-O体系的反应特性, 我们开展了这方面的研究工作, 并取得了突破性进展. 本文采用中温水热技术合成了含有机基团的砷矾超分子化合物2**4H2O, 探讨这类化合物的非线性光学性质、催化性质及其它功能特性将是一个非常有意义的研究领域.     

超临界NaCl水溶液的分子动力学模拟

采用分子动力学模拟的方法对超临界NaCl水溶液的微观结构进行了研究.模拟发现在所研究超临界条件下,密度的变化比温度的变化对超临界NaCl水溶液的微观结构影响更大.温度及密度对Cl－ H2O径向分布函数的影响比对Na＋ H2O径向分布函数的影响要大.超临界条件下,各gNa＋－Cl－在0.261 nm处出现峰值,表明Na＋、Cl－之间发生了离子的缔合.超临界条件下,随温度增加,缔合作用增强；随密度增加,缔合作用减弱.本文工作为建立可适用于超临界条件下的电解质热力学模型提供了依据.     

Rapid—In—situ Determination of Chromium （VI） in Water Using Modified Diphenylcarbazine with Citrate

In recent years, the determination of Cr (VI) has attracted great attention because of its toxicity to human, plants and animals1-5. Usually, in the industrial waste water, the concentration of Cr (VI) is relatively high and should be determined frequently. So, an accurate, quick, and convenient method for the measurement of Cr (VI) in environmental water, as well as in river, lake, sea and tap water, is of great importance. The method for determination of Cr (VI) by diphenylcarbazine …