新铌酸盐Ba5NdTi3Nb7O30的合成与介电性能

The New Niobate Ba₅NdTi₃Nb₇O₃₀ was synthesized by solid state reaction at 1250℃ for 48h. The crystal structure and dielectric properties of Ba₅NdTi₃Nb₇O₃₀ were determined by X-ray powder diffraction and dielectric measurements. The results show that Ba₅NdTi₃Nb₇O₃₀ belongs to ferroelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.24424(4)nm, c=0.39476(2)nm, calculated density 5.719g·cm^-3. Ba₅NdTi₃Nb₇O₃₀ belongs to relaxor ferroelectrics. The phase transition temperature (T_c) of Ba₅NdTi₃Nb₇O₃₀ from ferroelectric to paraelectric is found to shift toward higher temperature side at higher fre-quency, and T_c is 90℃ at 1kHz. At room temperature, the dielectric constant (ε_r) and dielectric loss of Ba₅NdTi₃Nb₇O₃₀ decrease with the increase of frequency, and Ba₅NdTi₃Nb₇O₃₀ ceramic have high dielectric constant 489 at 1kHz.     

钴（Ⅱ）与2,2’-联吡啶-1,1’-二氧化物的多核配合物的合成和性质

以无水CoCl2和2,2’-联吡啶-1,1’-二氧化物为原料,在DMF溶剂中合成了一种多核配合物.经元素分析、紫外光谱、红外光谱和摩尔电导等方法测得它的组成为[Co3(bipyO2)4Cl4]Cl2,并对该配合物的气敏特性进行了研究. 结果表明, 该配合物对氨气有良好的敏感性和选择性.由它制作的传感器可望用于涉氨化工生产中氨浓度的自动测量和控制.     

14C-寡糖在西瓜幼苗植株体内吸收传导和分布

应用同位素示踪技术研究了14C-寡糖在西瓜幼苗植株体内的吸收、传导和分布行为.自显影结果显示,寡糖通过处理叶部或根部后能够被西瓜幼苗植株快速吸收,在叶片中的传导表现为从叶缘向叶片中心分布的趋势.将叶部处理8h和根部处理24h后,14C-寡糖即可以传导和分布到西瓜幼苗的整个植株体内,证明14C-寡糖在西瓜幼苗植株体内具有较强的扩散和向基或向顶传导特征.结果表明,处理叶部4～120h时,根系、茎与未被直接处理的叶片等其它部位的放射性比活度分别由0.18×105和23.08×105Bq/kg变化为0.32×105和3.02×105Bq/kg,总体上表现出向基传导和分布的态势.处理根部4～120h时,西瓜幼苗植株根系、茎部、子叶和真叶中放射性比活度分别由22.23×105,2.23×105,8.33×105和12.78×105Bq/kg变化为431.11×105,42.23×105,65.57×105和78.89×105Bq/kg,表现出14C-寡糖在西瓜幼苗植株体内向顶传导作用和在地上部的积累态势很强.     

微生物降解塑料的研究进展

聚羟基脂肪酸酯(PHAs)是许多原核微生物在不平衡生长条件下合成的细胞内能量和碳源储藏性物质,作为完全可生物降解的热塑性聚酯而倍受关注。它除了具有与化学合成高分子相似的性质外,还具有比重大、光学活性好、透氧性低、抗紫外线辐射、生物可降解性、生物组织相溶性、压电性和抗凝血性等特点,因而在电子、光学、农业、生物医学、食品包装等领域具有广阔的应用前景。本文主要综述了近几年来国内外对PHAs微生物合成的研究进展,同时对PHAs的应用前景进行了展望。     

取代二噁二唑硫醚及砜衍生物合成及抗菌活性

取代二噁二唑硫醚及砜衍生物合成及抗菌活性     

呋喃甲醛缩二乙撑三胺希夫碱铜配合物的合成及结构(英)

A novel copper(Ⅱ) complex CuL(NO₃)₂(where L=N,N′-bis(furaldehyde)-diethylenetriamine) was synthesized and characterized by X-ray crystallography analysis. The crystal belongs to monoclinic, space group C2/c with cell parameters a=1.924 0(6) nm, b=0.792 8(3) nm, c=2.504 1(8) nm, β=111.163(5)°, and Z=8. The coordination geometry around Cu(Ⅱ) is a distorted trigonal-bipyramid，and one-dimensional chain is formed through intermolecular hydrogen bonds. CCDC: 255629.     

液固流化床内床层动态特性的CFD模拟

在对液固流化床内流动特性进行理论分析的基础上，采用多相流CFD方法模拟了二维矩形流化床内水和玻璃球体系的流体动力学特性。实验结果表明，流体速度突变后，液固流化床从一个平衡状态向另一个平衡状态过渡。当液体速度减小时，床层表面及分隔界面的变化与理论模型预测一致；由于重力不稳定性的影响，当液体速度增大时，床层表面稳定上升但与时间不呈线性关系，且分隔界面难以分辨。进而膨胀后停留时间的长短对收缩过程的影响也可以忽略。尽管床层收缩时间明显小于实际膨胀时间，但是与预报的理想膨胀时间比较接近。模拟结果与前人的实验研究和理论分析相吻合，表明多相流CFD模拟可以很好地预测液固流化床的床层动态行为。     

Fe-Ni-B-O纳米合金的合成及其催化制氢性能的研究

Preparation and catalytic performance of Fe-Ni-B-O nano-alloy having crystal-palpus structure has been studied. Black powder was synthesized by reducing mixture solution of Fe²⁺, Ni²⁺ with KBH₄ as reducing agent and polyethylene glycol as dispersant. Fe-Ni-B-O nano-alloy of crystal-palpus structure was obtained after hydrogen reduction of black powder. TEM shows that crystal-palpus length is 200～400 nm, diameter is 2～4 nm. The analytic results indicate that the total content of Fe and Ni is 86.6%, B is 5.08%. The alloy exhibits excellent catalytic performance. Hydrogen generation rate can approach 100% especially when pH is 8.     

Mn位掺杂钙钛矿结构化合物LaSr2Mn2-xNixO7的磁性和电性的研究

The effect of Ni substitution for Mn on magnetic and transport properties has been investigated for layered manganese oxides LaSr₂Mn_2-xNi_xO₇. Nickel doping hampered the canted antiferromagnetic (AFM) exchange at low temperature and their Neel temperature (T_N) decreased from 138 K (x=0) to 102 K (x=0.3). Meanwhile, spin glass, charge ordering and metal-insulator transition are suppressed by Ni addition. The resistivity increases obviously with increasing x due to double exchange interaction channel broken by Ni²⁺ addition. The resistivity of all samples in low temperature range fits to the Mott′s variable rang hopping (VRH) model, while it fits to nearest neighbor hopping of small polarons model in high temperature range.     

溴原子取代对二茂铁液晶化合物介晶性的影响

二茂铁液晶因其独特的稳定性和易于衍生化受到研究人员的青睐[1- 8] 。我们曾经报道过一类单取代二茂铁液晶的合成与介晶性[9] 。这里我们报道另外一类二茂铁单取代液晶 ,并对分子的长度、溴原子取代对介晶性的影响进行探讨。合成路线如下 :1　实验部分ＢｒｕｃｋｅｒＡＣＥ -2 0 0ｓｐｅｃｔｒｏｍｅｔｅｒ,ＣＤＣｌ3作溶剂。ＮｉｃｏｌｅｔＭａｇｎａ-ＩＲ 5 0 0Ｓｐｅｃｔｒｏｍｅｔｅｒ,ＳｅｒｉｅｓⅡ ,ＫＢｒ压片。ＷＲＳ -ＩＡ ,ＣａｒｌｏＥｒｂａ 1 1 0ｂ。Ｐｅｒｋｉｎ -Ｅｌｍｅｒ 7Ｓｅｒｉｅｓ热分析仪 ,分温速度 1 0℃ /ｍｉ…