Selective water sorbents for multiple applications, 3. CaCl2 solution confined in micro- and mesoporous silica gels: Pore size effect on the “solidification-melting” diagram

In this communication we present a low-temperature “solidification-melting” phase diagram for CaCl₂/H₂O solutions confined in KSK and KSM silica gels. At salt concentrations of 0–48 wt. %, the diagram has been found to lie below the diagram reported for the bulk system by 15–30°C. It shows a depression of the solution melting point due to its confinment to the pores. Several other peculiarities of melting and solidification in this system are also reported and discussed. Beside fundamental interest, the data obtained could be of importance in many commercial areas such as refrigeration, accumulation of low temperature heat, frost prevention in building materials,etc.     

Monte Carlo simulation of a lattice model for ternary polymer mixtures

Monte Carlo studies of symmetrical polymer mixturesAB, modelled by selfavoiding walks withN _A =N _B =N steps on a simple cubic lattice, are presented for arbitrary concentrations of vacancies _v in the range from _v =0.2 to _v =0.8 and chain lengthsN64. We obtained the phase diagrams and the equation of state for three choices of the ratio / _AB ( being the energy between monomers of the same kind, _AB being the energy between different monomers). Flory-Huggins theory provides only a qualitative understanding of these results. If the equation of state is fitted with an effective Flory-Huggins parameter _eff , the latter turns out to be strongly dependent on both concentration and temperature.Contributed paper delivered at the Tagung der Deutschen Physikalischen Gesellschaft, Fachausschuß Polymerphysik, Berlin, March 30–April 3, 1987.     

The phase diagram and tetragonal superstructures of the rare earth cobaltate phases Ln1−xSrxCoO3-δ (Ln=La, Pr, Nd, Sm, Gd, Y, Ho, Dy, Er, Tm and Yb)

Single phase perovskite-based rare earth cobaltates (Ln_1−xSr_xCoO_3−δ) (Ln=La³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Gd³⁺, Dy³⁺, Y³⁺, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺; 0.67?x?0.9) have been synthesized at 1100°C under 1 atmosphere of oxygen. X-ray diffraction of phases containing the larger rare earth ions La³⁺, Pr³⁺ and Nd³⁺ reveals simple cubic structures; however electron diffraction shows orientational twinning of a local, tetragonal (I4/mmm; a_p×a_p×2a_p) superstructure phase. Orientational twinning is also present for Ln_1−xSr_xCoO_3−δ compounds containing rare earth ions smaller than Nd³⁺. These compounds show a modulated intermediate parent with a tetragonal superstructure (I4/mmm; 2a_p×2a_p×4a_p). Thermogravimetric measurements have determined the overall oxygen content, and these phases show mixed valence (3⁺/4⁺) cobalt oxidation states with up to 50% Co(IV). X-ray diffraction data and Rietveld techniques have been used to refine the structures of each of these tetragonal superstructure phases (Ln=Sm³⁺-Yb³⁺). Coupled Ln/Sr and oxygen/vacancy ordering and associated structural relaxation are shown to be responsible for the observed superstructure.     

Thermodynamique des melanges binaires LiPO3-Pb(PO3)2: Diagramme de phases et étude thermodynamique du liquide

Study of solid-liquid phase diagram of LiPO₃-Pb(PO₃)₂ binary system, in certain calcination conditions, shows the existence of several metastable phasis. When heated at a temperature of 723 K the binary mixtures lead uncompletely to a defined compound Pb₂Li(PO₃). On heating these ternary solid mixtures, three eutectic reactions have been observed: LiPO₃+Pb(PO₃)₂→Liquid at a temperature of 793 K(1) LiPO₃+Pb₂Li(PO₃)₅→Liquid at a temperature of 843 K (2) Pb₂Li(PO₃)₅+Pb(PO₃)₂→Liquid at a temperature of 891 K (3) The metastable liquid phase appears in the system at temperature of 793 K. DTA experiments performed on the binary LiPO₃-Pb(PO₃)₂ mixtures, show a superposition of two diagrams. The first one is metastable and the second represents the stable equilibrium phase diagram. Measurements of liquid enthalpy of binary LiPO₃-Pb(PO₃)₂ system at temperature of 979.65 K were reported. The corresponding values were very small and so the binary system can be considered as athermal. Assuming an ideal behaviour, the liquidus curves in the metastable diagram were calculated and the eutectic reaction (LiPO₃-Pb(PO₃)₂→Liquid) was confirmed at 793 K. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phase Diagram for the RbBr–CuBr System

The phase diagram for the RbBr–CuBr system has been determined. In the system two intermediate compounds are formed: RbCu₂Br₃, melting congruently at 537 K and Rb₃CuBr₄, melting incongruently at 544 K. The coordinates of the two eutectic points are: 501 K, 54 mole% CuBr and 522 K, 74 mole% CuBr. This revised version was published online in July 2006 with corrections to the Cover Date.     

计算机图解法确定掩蔽剂存在下微溶物沉淀的pH值

采用计算机图解法，以副反应系数为主变数，应用Excel电子表格和Origin作图程序进行计算、作图，可以极为简便地确定在掩蔽剂存在下，微溶物开始沉淀时和完全沉淀时的pH值，图形直观明了，具有确定的物理意义。     

水泥-矿粉颗粒级配与流变性能关系的研究

将不同颗粒群分布的矿粉(即矿渣微粉,后同)、水泥按一定比例匹配,测其净浆流变性能指标及净浆标准稠度用水量,应用Origin软件,以宏观性能指标为z轴,水泥与矿粉D50(颗粒体积分数为50％时对应的粒径值)差为x轴,水泥与矿粉混合样的粉体D50为y轴,进行三维区域图分析,并综合流变性及活性,给出了水泥-矿粉最佳匹配的定性范围。     

关于复习《高等数学》的几点建议

集中复习可以从具体至抽象,再具体进行.一,通过形象法,口诀法,类比法等来记忆基本的必须掌握的概念、定理、解题方法 (即具体 );二,通过图表法从整体上把握知识脉络 (即抽象 );三,利用练习法熟练应用巩固已有的知识 (即再具体 ).     

关于本原BCH码广义汉明重量的一个一般结果

由V．K．Wei(1991)提出的广义汉明重量概念已显示是线性分组码的一种基本描述参数，已发现它们在密码学应用的研究中和线性分组码最小网格图的研究中很有用途，这篇论考虑一般域上的一般本原BCH码的广义汉明重量，确定其后面的一些广义汉明重量取值，这个结果改进以往有关的结果。     

一种基于室内PC机传输的智能户外电子图文屏设计

介绍了一种利用PC机和单片机的串行口通信功能实现对LED大屏幕进行控制的系统。