Structures and magnetic properties of dicopper(II) and dinickel(II) complexes with end-on azido bridges

An asymmetric single EO azido bridged dinuclear copper(II) complex, [Cu₂(dmterpy)₂(μ-1,1-N₃)(N₃)₂] · NO₃ · (H₂O)₂1 [dmterpy = 5,5″-dimethyl-2,2′:6′,2″-terpyridine], and a double EO azido bridged dinuclear nickel(II) complex, [Ni₂(pbdiim)₄(μ-1,1-N₃)₂] · 2(N₃) · 6(H₂O) 2 [pbdiim = 2-(2′-pyridyl)benzo[1,2-d:4,5-d′]diimidazole], have been synthesized and characterized structurally and magnetically. Compound 1 consists of a single EO azido bridged Cu^II dimer in which each Cu^II ion is five-coordinated in the form of a distorted square-based pyramid. The N_(μ−1,1) atom holds on the apical position of one Cu^II pyramid with an elongated bond length of 2.305 Å and on the basal plane of another distorted Cu^II pyramid with a bond length of 1.991 Å. The Cu-N_(μ−1,1)-Cu angle is 117.4 (2)°. The copper(II) dimer forms a 1 D zig-zag chain via hydrogen bondings between azide ions, water molecules and the nitrate anion. Compound 2 consists of a double EO azido bridged Ni^II dimer with the Ni-N_(μ−1,1)-Ni bond angle of 102.96 (13)°. The coordination geometry of Ni^II is octahedral. Their magnetic properties have been measured in the range from 300 to 2 K and correlated with the molecular structures. Compound 1 shows weak ferromagnetic interactions within the copper(II) dimer (J = 2.88 cm⁻¹), despite the large EO azide bridge angle (117.4 (2)°). The intramolecular coupling between the Ni^II (S = 1) ions in compound 2 was found to be ferromagnetic (J = 27.87 cm⁻¹).     

A new cyano-bridged one-dimensional GdFe coordination polymer with o-phenanthroline as the blocking ligand: synthesis, structure, and magnetic properties

Synthesis, structural characterization, and magnetic properties of a new cyano-bridged one-dimensional iron (III)-gadolinium (III) compound, trans-[Gd(o-phen)₂(H₂O)₂(μ-CN)₂Fe(CN)₄]_n · 2no-phen (o-phen = 1,10-phenanthroline), have been described. The compound crystallizes in the triclinic space group with the following unit cell parameters: a = 10.538(14) Å, b = 12.004(14) Å, c = 20.61(2) Å, α = 92.41(1)°, β = 92.76(1)°, γ = 112.72(1)°, and Z = 2. In this complex, each gadolinium (III) is coordinated to two nitrile nitrogens of the CN groups coming from two different ferricyanides, the mutually trans cyanides of each of which links another different Gd^III to create -NC-Fe(CN)₄-CN-Gd-NC- type 1-D chain structure. The one-dimensional chains are self-assembled in two-dimensions via weak C-H?N hydrogen bonds. Both the variable-temperature (2-300 K, 0.01 T and 0.8 T) and variable-field (0-50 000 Gauss, 2 K) magnetic measurements reveal the existence of very weak interaction in this molecule. The temperature dependence of the susceptibilities has been analyzed using a model for a chain of alternating classic (7/2) and quantum (1/2) spins.     

Molecular cloning and expression analysis of three genes encoding starch synthase II in rice

Three starch synthase (SS) genes, OsSSII-1, OsSSII-2 and OsSSII-3, were identified in rice (Oryza sativa L.) and localized to chromosomes 10, 2 and 6, respectively. The three OsSSII full-length cDNAs were cloned, and the predicted amino acid sequences were found to share 52–73% similarity with other members of the plant SSII family. The SS activity of each OsSSII was confirmed by expression and enzyme activity assay in Escherichia coli. Expression profile analysis revealed that OsSSII-1 was expressed in endosperms, leaves and roots; OsSSII-2 was mainly expressed in leaves, while OsSSII-3 was mainly expressed in endosperms. Similar to the OsSSI proteins, the OsSSII-2 and OsSSII-3 proteins were found in the soluble as well as the starch-granule-bound fractions in rice. The roles of the OsSSII proteins in starch biosynthesis in rice and the evolutionary relationships of the genes encoding monocotyledonous and dicotyledonous class-II SS enzymes are discussed.Abbreviations CDS Coding domain sequence - EST Expressed sequence tag - GB Granule-bound - Glc Glucose - SS Starch synthase     

Fabrication of gelatin nanofibrous scaffolds using ethanol/phosphate buffer saline as a benign solvent

Electrospinning of natural polymer nanofibers useful for biomedical applications often requires the use of cytotoxic organic solvents. In this study, gelatin nanofibers are electrospun from phosphate buffer saline/ethanol binary mixtures as a benign solvent at ambient temperature. The influences of ionic strength, ethanol concentration, and gelatin concentration on the electrospinnability of gelatin solutions and the fiber microarchitectures are analyzed. The electrospun scaffolds retain their morphologies during vapor‐phase crosslinking with glutaraldehyde in ethanol and the subsequent removal of salts contained in the nanofibers via water rinsing. When fully hydrated, the mechanically preconditioned scaffolds display a Young's modulus of 25.5 ± 5.3 kPa, tensile strength of 55.5 ± 13.9 kPa, deformability of 160 ± 15%, and resilience of 89.9 ± 1.8%. When cultured on the gelatin scaffolds, 3T3 fibroblasts displayed spindle‐like morphology, similar to the cell's normal morphology in a 3D extracellular matrix. © 2012 Wiley Periodicals, Inc. Biopolymers 97:1026–1036, 2012.     

甘草有性生殖特性研究

本文利用扫描电子显微镜对乌拉尔甘草、光果甘草和胀果甘草花粉的超微结构进行观察;利用荧光显微镜确定乌拉尔甘草的授粉方式、花粉生活力和柱头活性以及授粉后受精时间。结果表明花粉超微结构为甘草的鉴别提供了一定的形态学依据;甘草的授粉方式属于闭花受精;花粉生活力在每天12:00时最强,去雄后超过四天的柱头已经不具备接受花粉的能力;对授粉后不同时间的雌蕊进行研究得出授粉后6h花粉管进入胚珠进行受精。本文主要对甘草的有性生殖特性进行了研究,为未来制定正确的选、育种策略提供理论依据。     

耐有机溶剂蛋白酶产生菌Bacillus cereusWQ9—2发酵条件及酶学性质

以蜡状芽孢杆菌Bacillus cereus WQ9—2为产耐有机溶剂蛋白酶的出发菌株,对其产酶条件进行优化并初步研究了其酶学性质。在单因素实验基础上,通过中心复合实验确定了产酶的最佳发酵条件为酵母粉8g/L,葡萄糖17g/L,KH2P040．5g／L,无水MgS040．3g／L,CaCl20．5g／L,NaCl1．0g/L;pH7．5。实验中发现采用低温发酵能大大缩短菌体产酶周期;通过优化发酵时间由最初84h缩短到48h,最高比酶活为3921U／mL。金属离子螯合剂1,10菲罗啉（1,10-phenanthroline）、乙二胺四乙酸（EDTA）对该酶有较强的抑制作用,表明该酶可能为金属蛋白酶;Ca2＋对该酶的活力及热稳定性有显著提高作用。     

大蒜辣素(二烯丙基硫代亚磺酸酯)性质及相关研究进展

大蒜辣素作为大蒜的主要生物活性物质因其不稳定性使用受到很大限制,本文综述了大蒜辣素的理化性质及稳定性和大蒜辣素制备及分析方法等研究的相关进展。     

ce‐Subpathway: Identification of ceRNA‐mediated subpathways via joint power of ceRNAs and pathway topologies

Competing endogenous RNAs (ceRNAs) represent a novel mechanism of gene regulation that may mediate key subpathway regions and contribute to the altered activities of pathways. However, the classical methods used to identify pathways fail to specifically consider ceRNAs within the pathways and key regions impacted by them. We proposed a powerful strategy named ce‐Subpathway for the identification of ceRNA‐mediated functional subpathways. It provided an effective level of pathway analysis via integrating ceRNAs, differentially expressed (DE) genes and their key regions within the given pathways. We respectively analysed one pulmonary arterial hypertension (PAH) and one myocardial infarction (MI) data sets and demonstrated that ce‐Subpathway could identify many subpathways whose corresponding entire pathways were ignored by those non‐ceRNA‐mediated pathway identification methods. And these pathways have been well reported to be associated with PAH/MI‐related cardiovascular diseases. Further evidence showed reliability of ceRNA interactions and robustness/reproducibility of the ce‐Subpathway strategy by several data sets of different cancers, including breast cancer, oesophageal cancer and colon cancer. Survival analysis was finally applied to illustrate the clinical application value of the ceRNA‐mediated functional subpathways using another data sets of pancreatic cancer. Comprehensive analyses have shown the power of a joint ceRNAs/DE genes and subpathway strategy based on their topologies.