柠檬酸钾对尿石患者和正常人尿液凝胶中草酸钙晶体生长的影响

采用扫描电子显微镜(SEM)和X射线衍射(XRD)方法,比较研究了防石药物柠檬酸钾(K3cit)在尿石患者尿液和正常人尿液制备的凝胶中对草酸钙(CaOxa)晶体生长的影响.没有加入K3cit时,CaOxa晶体均以一水草酸钙(COM)为主要晶相,加入K3cit后,不但COM晶体变得圆钝,比表面积减小,而且诱导了二水草酸钙(COD)生成.随着K3cit浓度从0.10增加到0.20 mol/L,在正常人尿液凝胶中COD晶体的百分含量从20;增加到45;,而在CaOxa结石患者尿液凝胶中,不但COD含量从10;增加到25;,而且K3cit可诱导草酸钙成核,从而产生大量的小尺寸草酸钙晶体,这有利于阻止草酸钙晶体变大形成尿石.本结果可为临床上治疗CaOxa结石提供启示.     

多层状碱式碳酸锌微晶的制备及其脱除Cu2+性能研究

以壳聚糖(CS)为生物模板,采用低温水热法成功制备出了多层状碱式碳酸锌(ZCHO)微晶.采用XRD、SEM和TG等手段对产物的结构、形态和热学性能进行了表征,结果表明,单个ZCHO微晶颗粒均是由许多ZCHO纳米片构成的.添加适量的CS对形成多层状ZCHO微晶起到了至关重要的作用.热重分析结果表明,CS辅助得到的碳酸锌微晶热稳定性较高.等温吸附实验表明,在室温下,多层状ZCHO微晶能有效脱除水体中的Cu2,去除量与浓度关系符合Freundlich模型.最后讨论了多层状ZCHO微晶大容量去除Cu2+的可能机理.     

海带硫酸多糖防止草酸钙结石形成的体外模拟

采用扫描电子显微镜、X射线衍射法和红外光谱在草酸钙(CaOxa)结石患者尿液中研究了从海带中提取的硫酸多糖(LSPS)的防石作用.结果表明,LSPS可以抑制一水草酸钙(COM)的成核和聚集,并诱导二水草酸钙(COD)晶体形成.随着ESPS浓度从0增加到0.005, 0.02和0.20 mg/ml,COD的百分含量从0分别增加到22;, 55;和100;.这些结果表明LSPS是抑制CaOxa结石形成的一种潜在药物.     

Cu2ZnSnS4纳米晶的溶剂热法制备和表征

利用溶剂热制备了Cu2ZnSnS4 (CZTS)球形纳米晶.采用X射线衍射(XRD)、拉曼光谱、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、能量色散谱(EDS)和紫外-可见分光光度计对产物的物相结构、形貌、化学组分及光学性能进行表征.结果表明:所制备的CZTS球形纳米晶具有锌黄锡矿结构,球形颗粒的直径为190～300 nm,每个球形颗粒是由很多平均尺寸大约24 nm的纳米晶构成.纳米晶具有锌黄锡矿结构,其禁带宽度约为1.55 eV.同时研究了反应前驱溶液中不同量的硫脲和氯化锌对所制备的CZTS纳米颗粒的结构、原子组分比和形貌的影响规律,并对其形成机理进行了初步探讨.     

电子显微分析在表征纳米晶体化学组分中的应用

纳米材料的化学组分及含量影响其光、电、声、热、磁等物理性能,电子显微分析是表征纳米晶体化学组分的重要方法之一.本文综述了X-射线能谱(EDS)、X-射线波谱(WDS)、电子能量损失谱(EELS)和选区电子衍射(SAED)等现代电子显微分析技术在表征纳米晶体化学组分、形貌、尺寸和结构等方面的应用及其研究进展,并比较了这些分析方法存在的差异,提出了其应用中存在的不足及今后的研发方向.     

炸药爆轰合成纳米金刚石及其应用

本文简介通过高能炸药合成球形纳米金刚石的一些研究进展.X射线衍射谱显示,得到的纳米金刚石微晶为立方结构金刚石;晶粒尺寸为4～6nm,并有很大的微应力.高分辨率透射电镜观察表明,金刚石微晶在形成过程中经历了液态碳微滴聚结长大的过程.在这种材料的应用方面,本文报道了纳米金刚石用于提高化学气相生长金刚石薄膜的成核率:其出色的场发射性能用于电子显示材料,以及用于耐磨、减摩材料的若干试验成果.     

Fe2O3对纳米晶尾矿微晶玻璃结构及性能的影响

以铁尾矿和金尾矿为主要原料,采用熔融法制备了添加0 ～ 20wt; Fe2O3的CaO-MgO-Al2O3-SiO2(CMAS)系纳米晶尾矿微晶玻璃,利用差示扫描量热分析(DSC)、X射线衍射分析(XRD)、红外光谱(IR)、扫描电镜(SEM)和综合力学性能仪等测试手段,研究了Fe2O3含量对该体系微晶玻璃显微结构及性能的影响.实验结果表明:随着Fe2O3含量的增加,样品的晶化温度和玻璃化转变温度逐渐降低;且Fe2O3可促进主晶相透辉石相(Mg0.6Fe0.2Al0.2) Ca(Si1.5Al1.5)O6的形成;同时Fe2O3能够有效减小透辉石相平均晶粒尺寸;另外,微晶玻璃的密度、显微硬度和耐碱性随晶粒尺寸的减小而增加,而抗折强度和耐酸性随晶粒尺寸的减小而降低.     

水淬电炉渣制备双晶相微晶陶瓷的析晶行为

以中钢滨海公司铁镍冶炼排放出的水淬矿热电炉渣为主要原料,通过复配、研磨、成型和高温烧结,制备成双晶相微晶陶瓷烧结体.通过正交实验和单因素实验验证,研究成核剂的添加量、球磨时间和焙烧温度等因素对双晶相微晶陶瓷强度的影响.并利用X-射线衍射分析(XRD)、热分析(TG、DTA(TG-DTA))和扫描电镜(SEM)等测试手段,研究不同焙烧温度下,形成的双晶相微晶陶瓷的物相组成、晶体结构和结晶度的变化规律,结合热分析曲线,讨论温度对电炉渣微晶陶瓷析晶行为的影响.结果表明:烧结温度是影响双晶相微晶陶瓷强度、晶粒尺寸和比例的关键,成核剂能够提高烧结体的强度,促进透辉石相和橄榄石相晶体的共生.当成核剂MnO2的加入量为5;,在1200℃烧结2h时,微晶陶瓷样品的抗弯强度可达59.8 MPa,形成品粒直径2～4μm的短柱状结构透辉石和斜方晶系橄榄石共存的双晶相微晶材料.     

花状CuInSe_2微晶的溶剂热合成与表征

采用溶剂热合成方法,以CuCl2·2H2O为铜源,InCl3·4H2O为铟源,Se粉为硒源,以乙二胺为溶剂,合成了CuInSe2粉末。利用场发射扫描电镜(FESEM)、X射线衍射仪(XRD)、紫外-可见分光光度计(UV-Vis)、X射线光电子能谱仪(XPS)等测试方法对样品的形貌、晶体结构、光吸收性能及相组分进行了表征,研究了反应时间、反应温度对产物的影响。结果表明:在160℃下反应18 h可以合成比较均匀的由厚度为100 nm左右的纳米片组成的花状CuInSe2微晶,花状CuInSe2微晶的平均直径在10μm左右。同时对其形成机理进行探讨。     

表面活性剂对钨酸铅低维粉体形貌的影响

以钨酸钠和醋酸铅为原料,分别加以表面活性剂聚乙二醇200和十六烷基三甲苯溴化铵,用沉淀法合成出钨酸铅纳米晶和菱形微晶.对样品进行X射线分析,结果显示样品结晶良好.对样品进行透射电子显微镜分析,结果显示钨酸铅纳米晶和菱形微晶成形良好,且分散性良好、无团聚发生.讨论了表面活性剂对钨酸铅低维粉体形貌的影响,认为PEG200对分散性良好的钨酸铅纳米晶的生成起了关键作用,而CTAB则促进了成形良好的菱形钨酸铅微晶的生成.     

Relationship of Morphological Types of Dynamic Forms of Crystals

Crystallography Reports - The relationship of morphological spectra (sets of data on the morphological types of real polyhedral crystals and their probabilities under current physicochemical...     

Development of Pauling's concepts of geometric characteristics of atoms

The evolution of the geometric characteristics introduced by Pauling and their dependence on the specific features of the structure and chemical bonds have been considered. The values of the covalent and van der Waals radii are given as well as their relationships and mutual transitions.     

A review of measurement of thermophysical properties of silicon melt

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi₃ existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.     

Generation of crystal structures of heteromolecular compounds by the method of discrete modeling of packings

Within the method of discrete modeling of packings, an algorithm of generation of possible crystal structures of heteromolecular compounds containing two or three molecules in the primitive unit cell, one of which has an arbitrary shape and the other (two others) has a shape close to spherical, is proposed. On the basis of this algorithm, a software package for personal computers is developed. This package has been approved for a number of compounds, investigated previously by X-ray diffraction analysis. The results of generation of structures of five compounds—four organic salts (with one or two spherical anions) and one solvate—are represented.     

Investigation of the Mechanism of Influence of Stress Corrosion on the Development of Macroplastic Instabilities of Aluminum–Magnesium Alloy

Crystallography Reports - Macroscopic jumps of plastic deformation (few percent in amplitude) on creep curves of aluminum–magnesium alloy, caused by a local effect of concentrated solution of...     

Comparative analysis of two methods of calculation of the orientation of domain walls in ferroelastics

Two types of domain-wall equations are analyzed: the equations derived by the Sapriel method and the equations obtained by interface matching of the thermal-expansion tensor. It is shown that, for W-type domain walls, these methods yield the same equations. For W′-type domain walls, the equations obtained by different methods coincide for proper ferroelastics and differ for improper ferroelastics.     

Dependence of the parameters of equations of viscous flow on chemical composition of silicate melts

The temperature dependence of viscosity of silicate melts is discussed in the framework of the Avramov–Milchev (AM) equation. The composition is described by means of two parameters: the molar fraction, x, and the “lubricant fraction”, l. The molar fraction is the sum of the molar parts x_i of all oxides dissolved in SiO₂, the molar fraction of the latter being 1 ? x. It is shown that, with sufficient precision, two of the parameters of the AM equation can be presented as unique functions of the molar fraction. On the other hand, x is not sufficient to determine properly the reference temperature T_r , at which viscosity is η_r = 10¹³ [dPa.s]. Therefore, additional parameter, “lubricant fraction” l, is introduced. For each of the components, l_i is a product of molar part x_i and a specific dimensionless coefficient 0 ≤ k_i ≤ 1 accounting for the specific contribution of this component to the increased mobility of the system. It is demonstrated that, for l > 0, the reference temperature is related to the “lubricant fraction” l through the reference temperature T_r,SiO2 of pure SiO₂.     

A SAXS study of kinetics of aggregation of silica sols

SAXS in situ experiments on the evolution of TMOS solutions during hydrolysis and polycondensation lead to power laws with scaling exponents ≈ 2. It is suggested that this could be the result of the polydispersity of the samples and that only an apparent fractal dimension can be obtained in this way. Kinetic studies tend to indicate that agglomeration in the sol is the result of a diffusion-controlled process.     

Study of the possibility of interactive control of the surface profile of X-ray optical elements

We investigate the possibility of controlling the curvature parameters of parabolic mirrors that are modular elements of two types consisting of a base and thin inserts placed at the opposite side of the work surface. In the first type of modular elements, bending is controlled by the difference in the coefficients of the thermal expansion of the base and inserts. In the second type of elements, the profile is changed by the piezoelectric straining of the inserts under an electric field. A correlation is established between the parameters of modular elements and their surface curvature profile.