1-甲基-2-咪唑醛肟锰(Ⅲ)配合物的合成、晶体结构及电化学性质研究

采用溶剂扩散法制备了锰(Ⅲ)的两个单核配合物[Mn(Miao)2(H2O)2]ClO4(1)和[Mn(Miao)2(DMF)2]ClO4(2)(HMiao=1-甲基-2-咪唑醛肟,DMF=N,N-二甲基甲酰胺)的晶体.X射线衍射单晶结构表明:两种配合物均属三斜晶系,空间群Pi锰与配体形成变形的八面体结构.采用Gaussian 03W程序计算了HMiao配体的电荷密度,理论计算与实际配位形式完全吻合.测定了两种锰配合物在DMF溶液中的电化学性质,循环伏安法表明两配合物均存在较好的氧化还原性,其氧化还原峰分别为0.75和0.70V,-0.32和-0.50 V,是Mn(Ⅲ)和Mn(Ⅱ)之间的相互转化.     

Calorimetric and thermal decomposition kinetic study of Tb(Tyr)(Gly)<Subscript>3</Subscript>Cl<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O

The solid-state ternary complex of terbium chloride with L-tyrosine and glycine, [Tb(Tyr)(Gly)₃Cl₃·3H₂O], was synthesized and characterized. Using a solution-reaction isoperibol calorimeter, the enthalpy of reaction for the following reaction, TbCl₃·6H₂O(s)+Tyr(s)+3Gly(s)=Tb(Tyr)(Gly)₃Cl₃·3H₂O(s)+3H₂O(l), was determined to be (5.1±0.6) kJ mol^-1. The standard enthalpy of formation of Tb(Tyr)(Gly)₃Cl₃-3H₂O at T=298.15 K has been derived as -(4267.3±2.3) kJ mol^-1. The thermal decomposition kinetics of the complex was studied by non-isothermal thermogravimetry in the temperature range of 325-675 K. Two main mass loss stages existed in the process of the decomposition of the complex, the kinetic parameters for the second stage were analyzed by means of differential and integral methods, respectively. Comparing the results of differential and integral methods, mechanism functions of the thermal decomposition reaction for its second stage were proposed. The kinetic equation can be expressed as: d/dt=Aexp(-E/RT)(1-)². The average values of the apparent activation energy E and pre-exponential factor A were 213.18 kJ mol^-1 and 2.51·10²⁰ s^-1, respectively.     

Low level determination of manganese in biological reference materials by neutron activation analysis

A simple method was developed for the low level determination of manganese in biological materials by neutron activation analysis with radiochemical separation based on manganese dioxide precipitation. Precision and accuracy of the method were tested by analyses of IAEA reference materials Animal Muscle H-4, Milk Powder A-11, Freeze Dried Animal Blood A-13, Horse Kidney H-8, and Mixed Human Diet H-9. Interferences from iron and cobalt were also evaluated.     

RGDS‐ and SIKVAVS‐Modified Superporous Poly(2‐hydroxyethyl methacrylate) Scaffolds for Tissue Engineering Applications

Three‐dimensional hydrogel supports for mesenchymal and neural stem cells (NSCs) are promising materials for tissue engineering applications such as spinal cord repair. This study involves the preparation and characterization of superporous scaffolds based on a copolymer of 2‐hydroxyethyl and 2‐aminoethyl methacrylate (HEMA and AEMA) crosslinked with ethylene dimethacrylate. Ammonium oxalate is chosen as a suitable porogen because it consists of needle‐like crystals, allowing their parallel arrangement in the polymerization mold. The amino group of AEMA is used to immobilize RGDS and SIKVAVS peptide sequences with an N‐γ‐maleimidobutyryloxy succinimide ester linker. The amount of the peptide on the scaffold is determined using ¹²⁵I radiolabeled SIKVAVS. Both RGDS‐ and SIKVAVS‐modified poly(2‐hydroxyethyl methacrylate) scaffolds serve as supports for culturing human mesenchymal stem cells (MSCs) and human fetal NSCs. The RGDS sequence is found to be better for MSC and NSC proliferation and growth than SIKVAVS.

     

Liquid chromatography of carbon clusters

Summary A comparison of three binary mobile phases in LC separation of C₆₀ and C₇₀ fullerences on chemically bonded 2,4-dinitroanilinopropyl (DNAP) stationary phase was carried out, n-Hexane-benzene has been found to be the best mobile phase for efficient separation of the all-carbon molecules permitting high loads in preparative LC.     

Role of polar and apolar moieties in water adsorption by humic acids under arid conditions

Journal of Thermal Analysis and Calorimetry - In arid soils, humic acids (HAs) are used as amendments to improve water uptake from the atmosphere. This method of harvesting water involves several...     

An existence theorem for the Boussinesq equations with non-Dirichlet boundary conditions

The evolution Boussinesq equations describe the evolution of the temperature and velocity fields of viscous incompressible Newtonian fluids. Very often, they are a reasonable model to render relevant phenomena of flows in which the thermal effects play an essential role. In the paper we prescribe non-Dirichlet boundary conditions on a part of the boundary and prove the existence and uniqueness of solutions to the Boussinesq equations on a (short) time interval. The length of the time interval depends only on certain norms of the given data. In the proof we use a fixed point theorem method in Sobolev spaces with non-integer order derivatives. The proof is performed for Lipschitz domains and a wide class of data.     

On free semilattice-ordered semigroups satisfying x n =x

Let B(k,0,n) denote the group with k generators which is free in the group variety defined by the identity x ⁿ =1. Let B _slo (k,1,n) denote the semilattice-ordered semigroup with k generators which is free in the semilattice-ordered semigroup variety defined by the identity x ⁿ =x. We prove a generalization of the Green-Rees theorem: B _slo (k,1,n) is finite for all k≥1 if and only if B(k,0,n−1) is finite for all k≥1. We find a formula for card(B _slo (1,1,n)). We construct B _slo (k,1,n) for some concrete values of k and n.