High-pressure sintered yttria stabilized zirconia ceramics

Fast densification of 8YSZ ceramics under a high pressure of 4.5 GPa was carried out at different temperatures (800, 1000, 1450 degrees C), by which a high relative density above 92% could be obtained. FT-Raman spectra indicate that the 8YSZ underwent a phase transition from partially tetragonal to partially cubic phase as temperatures increase from 1000 to 1450 degrees C when sintering under high pressure. The electrical properties of the samples under different high-pressure sintering conditions were measured by complex impedance method. The total conductivity of 0.92 x 10(-2) S cm(-1) at 800 degrees C has been obtained for 8YSZ under high pressure at 1450 degrees C, which is about 200 degrees C lower than that of the samples prepared by conventional pressureless sintering.

Core Crosslinking of Biodegradable Block Copolymer Micelles Based on Poly(ester carbonate)

A biodegradable amphiphilic block copolymer, PEG-b-P(LA-co-MAC), was used to prepare spherical micelles consisting of a hydrophobic P(LA-co-MAC) core and a hydrophilic PEG shell. To improve their stability, the micelles were crosslinked by radical polymerization of the double bonds in the hydrophobic blocks. The crosslinked micelles had similar sizes and a narrow size distribution compared to their uncrosslinked precursor. The improved stability of the crosslinked micelles was confirmed by measurements of the CMC and a thermodynamic investigation. These micelles can internalize into Hela cells in vitro as demonstrated by inverted fluorescence microscopy and CLSM. These stabilized nanoscale micelles have potential use in biomedical applications such as drug delivery and disease diagnosis.

Effect of Y for enhanced age hardening response and mechanical properties of Mg-Gd-Y-Zr alloys

In this study, compositional dependence of age hardening response and tensile properties were investigated for Mg-10G(d-x)Y-0.4Zr (x = 1, 3, 5 wt.%) alloys. With increasing Y content, the age hardening response of the alloys enhanced and tensile properties increased. The Mg-10Gd-5Y-0.4Zr alloy exhibited maximum tensile strength and yield strength at aged-peak hardness, and the values were 302 MPa and 289 MPa at room temperature, and 340 MPa and 267 MPa at 250 degrees C, respectively. The strong peak age hardening was attributed to the precipitation of prismatic beta' plates in a triangular arrangement. The cubic shaped beta phase was also observed at grain boundaries. The remarkable improvement in strength is associated with a uniform and high dense distribution of beta' and cubic shaped beta precipitate phases in Mg matrix. Elongation of Mg-10Gd-0.4Zr alloys decreased with increasing Y content, and the elongation of Mg-10Gd-5Y-0.4Zr alloy was less than 3% below 250 degrees C, whereas the alloys containing I wt.% and 3 wt.% Y exhibited higher elongation than 5% at room temperature.

High strength Ni based composite reinforced by solid solution W(Al) obtained by powder metallurgy

The solid-solution-particle reinforced W(Al)-Ni composites were successfully fabricated by using mechanical alloying (MA) and hot-pressing (HP) technique when the content of Ni is between 45 wt% and 55 wt%. Besides, samples of various original component ratio of Al50W50 to Ni have been fabricated, and the corresponding microcomponents and mechanical properties such as microhardness, ultimate tensile strength and elongation were characterized and discussed. The optimum ultimate tensile strength under the experiment conditions is 1868 MPa with elongation of 10.21 % and hardness of 6.62 GPa. X-ray diffraction (XRD), FE-SEM and energy dispersive analysis of X-rays (EDS) were given to analysis the components and morphology of the composite bulk specimens.

Crystal structures of EtEDTB center dot 1.4C(2)H(5)OH center dot 5H(2)O and H4EtEDTB(ClO4)(4)center dot C2H5OH (EtEDTB=N, N, N ', N '-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine)

The crystal structures of EtEDTB.1.4C(2)H(5)OH.5H(2)O 1 and H4EtEDTB(ClO4)(4).C2H5OH 2 (EtEDTB = N, N,N',N'-tetrakis[2-(1-ethylbenzimidazolyl)methyl]-1,2-ethanediamine) have been determined by single-crystal X-ray diffraction method. Compound 1 crystallizes in the space group P(1) over bar with a = 11.489(2), b = 11.866(3), c = 12.002(3) Angstrom, alpha = 97.47(2), beta = 114.564(13), gamma = 114.11(2)degrees, V = 1266.6(5) Angstrom(3), Z = 1, M-r = 847.48, D-c = 1.111 g/cm(3), F(000) = 456 and mu(MoKalpha) = 0.076 mm(-1). A total of 5207 reflections were measured for 1, of which 4323 were independent. The structure of 1 was solved by direct methods and refined by full-matrix least-squares technique to the final R = 0.0706 and wR = 0.1802 for 1318 observed reflections with I > 2sigma(I). In the structure of 1, centrosymmetric EtEDTB molecules are linked by hydrogen bonds through water and ethanol to form 2-dimensional network. Compound 2 crystallizes in the space group C2/c with a = 24.260(5), b = 13.040(3), c = 17.680(4) Angstrom, beta = 97.50(3)degrees, V = 5545.2(2) Angstrom(3), Z = 4, M-r = 1140.80, D-c = 1.366 g/cm(3), F(000) = 2384 and mu(MoKalpha) = 0.289 mm(-1).

Luminescence and energy transfer properties of Ca2Gd8(SiO4)(6)O-2 : A(A = Pb2+, Tm3+) phosphors

Ca2Gd8(SiO4)(6)O-2: A(A = Ph2+, Tm3+) phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), scanning electron microseopy(SEM) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 degreesC. SEM study reveals that the average grain size is 300 similar to 1000 nm. In Ca2Gd8(SiO4)(6)O-2: Tm3+ phosphors, the Tm3+ shows its characteristic blue emission at 456 nm (D-1(2)-F-3(4)) upon excitation into its H-3(6)-D-1(2)(361 nm), with an optimum doping concentration of 1 mol% of Gd3+ in the host lattices. In Ca2Gd8(SiO4)(6)O-2: Pb2+, Tm3+ phosphors, excitation into the Ph2+ at 266 nm (S-1(0)-P-3(1)) yields the emissions of Gd3+ at 311 nm (P-6-S-8) and Tm3+ at 367 nm (D-1(2)-H-3(6)) and 456 our (D-1(2)-F-3(4)), indicating that energy transfer processes of Pb2+-Gd3+ and Ph2+-Tm3+ have occur-red in the host lattices.

Confined crystallization behavior of PCL in organic-inorganic hybrid system

poly(epsilon-caprolactone) (PCL) and silica (SiO2) organic-inorganic hybrid materials have been synthesized by sol-gel approach and the crystalline behavior of PCL in the silica networks has been investigated by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The degree of PCL crystallinity in the PCL/SiO2 hybrid networks reduces with the increase of SiO2 content. PCL is in an amorphous state when the concentration of PCL is lower than 40wt% in the hybrid materials. The melting points of PCL in the networks are lower than that of pure PCL,but they almost have a same value. WAXD results show that when the PCL weight percentage is higher than 40wt% in the hybrid samples,part of PCL can crysatllize and the PCL crystallites are almost in a same size. That means the crystalline movement of PCL molecular chains is strictly confined by the porous gel. The crystalline PCL in the hybrid samples is relatively free from the composition of the materials, because the crystallization temperature and melting point of PCL of the samples are almost equal,and the crystalline PCL of different samples has the same crystalline structure and the same crystallite sizes L-110 and L-200, that means the crystalline part of PCL in the hybrid samples is unperturbed and the porous silica gel gives enough space for PCL to crystallize into the same crystalline structure and the same size crystallites.

聚己内酯在有机/无机杂化体系中的受限结晶行为

通过Sol Gel技术合成了聚己内酯 (PCL) /二氧化硅 (SiO2 )杂化材料 ,并对杂化样品进行了DSC和WAXD测试 .实验结果表明杂化样品中PCL的结晶度随二氧化硅含量增加而减小 ,当样品中二氧化硅含量达到 60 %时 ,PCL为非晶态 ;含有PCL结晶的杂化样品中PCL熔融温度基本相同 ,但是比纯PCL的熔融温度低 .杂化样品中结晶PCL的结晶结构和微晶尺寸和纯PCL的一致 .这说明杂化材料中PCL的结晶行为和结晶度受到了限制 ,含PCL结晶的样品中PCL的结晶结构和微晶尺寸并没有受到影响.

硝基苯类化合物的结构/毒性定量构效关系研究

为了定量结构 /毒性相关性研究提取了拓扑指数Am ,分子连接性指数mχt量子化学参数及分子体积等 ,同时运用最佳变量子集算法 (LeapsandBounds)进行了变量的压缩和选择 .进而实施了多元间归分析 ,并由所得结果进行了硝基苯类化合物结构与毒性关系的理论解释 .同时还进行了人工神经网络法对于该类化合物毒性的预测 ,其结果明显好于多元回归法.

恒电位电解法掺稀土对多孔硅光致发光性能的影响

研究了恒电位电解法掺稀土(Er、Nd与Yb)对多孔硅(PS)室温可见区光致发光性能的影响。结果表明:适当高浓度稀土的掺入可以提高PS的发光强度、使PS发光波长蓝移;掺入稀土浓度过高对PS的发光起猝灭作用。掺稀土可以缩短PS发光衰减的平均寿命,而不影响衰减曲线的形状。提出用“表面态辅助的量子限制效应”观点来解释PS和掺稀土多孔硅的光致发光。

聚酰亚胺、聚砜、聚醚砜及其共混改性中空纤维膜用于醇/醚气相分离的研究

甲醇/甲基叔丁基醚的分离是目前具有实用意义的重要研究课题之一，采用气流吹扫式操作，研究了聚酰亚胺、不同结构的聚砜中空纤维膜在不同操作条件下，对甲醇/ 甲基叔丁基醚气相混合体系的分离性能，也研究共混改性对分离膜性能的影响。结果表明，各种材料的膜具有相近的分离行为，即随着气相中甲醇含量的增加，透过通量逐渐增大而分离系数逐渐减小，聚酰亚胺膜具有适中的透过通量，但具有很高的分离系数，在甲醇浓度低于20% 时，分离系数可达数千。采用聚醚砜共混改性的聚酰亚胺膜在未明显降低透过通量的条件下，使醇/ 醚分离系数大幅度提高，有很好的应用前景。

Nonlinear optical properties of (B3O7)(5-) and (B3O6)(3-) groups

From the chemical bond viewpoint, LiB3O5 (LBO) crystal has been studied by using the bond valence theory of complex crystals. Chemical bond parameters and linear and nonlinear optical (NLO) properties of each type of constituent chemical bonds are quantitatively determined. Because of the different crystal structure characteristics of LBO from those of beta-BaB2O4 (BBO), the two anionic groups, (B3O7)(5-) in LBO and (B3O6)(3-) in BBO, play different roles in contributions to their own total NLO tensor coefficients of LBO and BBO, respectively. By comparison, we find that planar (B3O6)(3-) groups are the ideal structure model, leading to little cancellation of contributions of each kind of bond in these groups, and this gives us a useful guide to design new NLO materials in the future.

EVAc共聚物的序列结构和它的~(13)C NMR谱的关系

本文以EVAc共聚物为例,阐述了EV共聚物序列结构的符号表示与Bovey关系(Ⅰ)的一致性。在此基础上,选择了EV共聚物序列结构的Sung表示并赋予它以化学位移的意义,在二元组和三元组序列水平上分析了EV共聚物的13种序列结构与Sung表示,与取代基参数,与其~(13)C NMR谱13个谱峰之间的一一对应关系。其主要内容由Sung表示与取代基参数之间的α～S_1,β～S_2,γ～S_3,δ～S_4,δ~+～0ppm对应关系表征,从而构架了由EV共聚物的~(13)C NMR谱通向其序列结构的桥梁,建立起研究EV共聚物序列结构的普适方法。

掺W对Bi系中高Tc超导相的影响

自Maeda发现高Tc超导体BiSrCaCuO以来,引起了人们广泛兴趣;由于它有较高的超导转变温度(Tc>100K),无剧毒、价廉和自高温冷却到室温无结构相变等特点,Bi系是一很有实用前景的高Tc超导体;已经确定Bi系中含有三个超导相(2201,2212,2223相),但是迄今要制得较纯的2223高Tc相还有一定困难,无疑这对它的基础研究和实用开发都受到了限制,因此制备更纯的Bi系2223相具有重要的意义。

η~6—芳烃希土有机配合物的合成、结构及性能研究——Ⅰ.Sm(η~6—C_6H_6)(AlCl_4)_3的合成及晶体结构

经过铝粉加热活化的AlCl_3与SmCl_3在苯中反应,得到了Sm(η~6—C_6H_6)(AlCl_4)_3·C_6H_6单晶.其晶体属于三斜晶系,P1空间群,晶胞参数a=9.456(2)(?),b=9.765(3)(?),c=16.776(4)(?),α=96.00(2)°,β=93.76(2)°,γ=111.66(2)°,V=1422.55(?)~3,Z=2.晶体结构是采用Patterson和Fourier合成法解出的,所有非氢原子的坐标及各向异性热振动参数经块矩阵最小二乘法修正,最后偏离因子R=0.031,R_ω=0.035.分子结构中,中心离子Sm(Ⅲ)与六个Cl原子及一个苯环上的六个C原子成键.Sm-C键平均距离2.92(?),Sm-Cl平均距离2.83(?).与希土相连的六个Cl原子,其中之五构成平面五边形,整个分子呈大致的五角双锥形.