A Three-dimensional Supramolecular Complex {[Co(H2btec)(2,2'-bipy)(H2O)3]·H2O}n Assembled via Hydrogen Bonding and π-π Stacking Interactions

A new cobalt compound, {[Co(H2btec)(2,2'-bipy)(H2O)3]·H2O}n (1, H4btec =1,2,4,5-benzenetetracarboxylic acid, 2,2'-bipy = 2,2'-bipyridine), has been synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR and X-ray powder diffraction. The crystal belongs to the triclinic system, space group P-1, with a = 7.230(3), b = 11.626(5), c =14.001(6) (A), α = 108.12(0)°, β= 95.85(0)°, V= 1095.33(157)(A)3, C20H20CoN2O12, Mr= 539.31,Z=2, Dc = 1.635 g/cm3,μ = 0.855 mm-1, F(000) = 554, R = 0.0427 and wR = 0.1042 for 3883 observed reflections (Ⅰ ＞ 2σ(Ⅰ)). The title compound features a discrete molecular structure, which is connected with each other through extensive O-H…O hydrogen bonds into an intricate 3D supramolecular network. Additionally, two different patterns of π-π stacking interactions further consolidate the framework.     

纺锤形BiVO_4微米管:低温离子熔盐合成及光催化性能

以Bi(NO_3)_3·5H_2O和NH_4VO_3为原料,以氯化胆碱和尿素组成的低温离子熔盐为反应介质,采用离子热合成法成功制备出了具有纺锤状外形的BiVO_4微米管。利用XRD,SEM,UV-Vis DRS,光催化测试等手段考察了BiVO_4颗粒的物相、形貌和光催化性能。结果表明,在离子熔盐环境下可以制备出结晶良好的BiVO_4纺锤形微米管,该BiVO_4微米管长10～15μm,直径为1.5μm左右,管壁厚约为200 nm。同时,研究了pH值对BiVO_4颗粒物相与形貌的影响,发现随着pH值的变化可分别合成出具有柱状、纺锤形微米管、柱状微米管和针柱状单斜相BiVO_4颗粒。光催化测试结果表明,这些单斜白钨矿BiVO_4颗粒在可见光范围都具有一定的光催化活性,其中纺锤状微米管对罗丹明B的降解效果最佳,可见光照射4.5h后罗丹明B的降解率可达到93%。     

KMgF3:Ce3+,Tb3+纳米粒子中Ce3+→Tb3+的发光及能量传递

利用微乳液方法,合成了铈、铽共掺杂的氟镁钾纳米粒子,研究了体系中Ce3+→Tb3+的发光特性以及它们之间的相互作用,结果表明KMgF3:Ce3+Tb3+纳米粒子中存在Ce3+→Tb3+的能量传递过程,即Ce3+可以将吸收的能量直接传递给Tb3+离子,使得Tb3+的绿色发光强度大为增加.     

NiCo_2O_4对H_2O_2在碱性溶液中电化学还原反应的催化行为(英文)

利用溶胶-凝胶法合成纳米NiCo2O4,并利用X射线衍射和透射电镜分析其结构和表面形貌.结果表明NiCo2O4具有尖晶石结构,平均粒径约为15 nm.利用电势线性扫描和恒电势法测定了其对H2O2在碱性溶液中电化学还原反应的催化性能.发现NiCo2O4对H2O2电化学还原具有高的催化活性和稳定性,在H2O2浓度低于0.6 mol.L-1时,其电化学还原反应主要通过直接还原途径进行.以NiCo2O4为阴极催化剂的Al-H2O2半燃料电池在室温下的开路电压达1.6 V;在1.0 mol.L-1 H2O2溶液中,峰值功率密度达209 mW.cm-2,此时电流密度为220mA.cm-2.     

炭载体改性对炭载Pd催化剂电催化性能的影响

研究了硝酸和氨水改性处理对活性炭表面基团、炭载Pd纳米粒子的形态及其对甲酸氧化电催化性能的影响.傅里叶变换红外(FT-IR)光谱、X射线光电子能谱(XPS)及Boehm滴定结果表明,硝酸和氨水处理分别增加了活性炭表面含氧基团和含氮基团的含量.透射电镜(TEM)及电化学测试显示,活性炭经硝酸处理后,表面负载的Pd粒子粒径降低,催化剂对甲酸氧化活性和稳定性提高.进一步用氨水处理后,Pd粒子的粒径没有明显变化,但催化剂中Pd0的含量增加,催化剂性能进一步提高.     

蜂蜜中泰妙菌素残留量的高效液相色谱-串联质谱法测定

建立了固相萃取-高效液相色谱-串联质谱(HPLC-MS/MS)测定蜂蜜中泰妙菌素残留量的分析方法。样品用甲醇-偏磷酸水溶液提取,OasisMCX SPE小柱净化,经C18色谱柱分离,以电喷雾离子源在正离子多反应监测(MRM)模式下进行测定,外标法定量。泰妙菌素的方法检出限为0.04μg/kg,定量下限为0.1μg/kg,在0.5～50μg/L范围内线性关系良好,相关系数r为0.999 8。在0.1～5.0μg/kg加标水平内泰妙菌素的回收率为80%～94%,RSD为4.5%～8.1%。该方法实用、准确、灵敏,适用于蜂蜜中泰妙菌素残留量的测定。     

MBA接枝聚丙烯微孔膜的亲水改性研究

运用表面吸附法使聚丙烯微孔膜表面覆盖上引发剂,然后浸入氮氮亚甲基双丙烯酰胺(MBA)水溶液在一定温度下进行接枝反应。研究了引发剂用量,单体浓度,反应时间与温度对接枝率的影响,并用红外、扫描电镜对聚丙烯膜接枝前后的微孔膜进行了表征。同时对膜的亲水性和水通量进行了测试,发现其亲水性能有了极大的提高,其中接枝改性后接触角与未接枝的相比降低了90°以上,吸水率最多提高了12%,但是水通量有所下降。还对改性微孔膜的抗污染性能进行了探究。     

紫外接枝聚合聚乙二醇甲基丙烯酸甲酯制备抗污染聚砜超滤膜

以二苯甲酮(BP)为紫外引发剂,将聚乙二醇甲基丙烯酸甲酯(PEGMA)接枝在聚砜超滤膜表面以提高膜的抗污染性能.在二苯甲酮存在的条件下,波长较长(λ300nm)的紫外光(UV)辐射下发生提氢反应,可以有效防止聚砜分子主链的剪切,保持改性膜的分离性能.考察了PEGMA浓度、UV辐射时间和BP浓度对改性超滤膜接枝度、亲水性和抗污染性能的影响.用表面全反射红外光谱(ATR/FTIR)表征改性前后膜表面化学组成的变化.表面改性膜的纯水通量略有降低而牛血清白蛋白(BSA)截留率有所提高.随着接枝度的提高,PEGMA接枝改性膜的抗污染性能增加.     

Analysis of a Critical Residue Determining Herbicide Efficiency Sensitivity in Carboxyltransferase Domain of Acetyl-CoA Carboxylase from Poaceae by Homology Modeling and Free Energy Simulation

Carboxyltransferase domain(CT) of acetyl-coenzyme A carboxylase(ACCase, EC 6.4.1.2) from a family of Poaceae is an important target of commercial herbicide APPs for controlling grass weed growth. As the abuse of APPs herbicides, the resistant ACCase due to the mutation of a single residue(Ile→Leu), which is lo-cated in CT active site, is emergent in many populations and species of Poaceae. So it is urgent to understand the re-sistant mecha-nism so as to design new effect herbicides. Herein lies the complex of CT dimmer from Lolium rigi-dum and herbicide haloxyfop successfully constructed for wild type enzyme and Ile/Leu mutant, respectively, pro-viding a basis for explaining the resistance from microscopic structure. Moreover, the binding free energy difference between wild type and mutant enzymes was predicted in good agreement with the known observation, and the various contributions to it were analyzed, by Molecular mechanics-Poisson-Boltzmann surface area(MM-PBSA) method. The results indicate the van der Waals interaction difference between the protein and inhibitor, –22.94 kJ/mol of CT wild type lower than that of mutant, is the major reason for resistance. Structure analysis further suggests that van der Waals interaction difference is originated from the steric hindrance between the side chain of mutated residue Leu and the chiral methyl group of haloxyfop. All these findings enhance the understanding of resistant mechanism of ACCase to herbicide by Ile/Leu mutation and provide an important clue for the rational design of high effective herbicides.     

静电纺丝制备多级结构TiO_2微纳米纤维

通过对共轴电纺内流体溶液浓度和流速的调控得到4种具有不同内部结构的TiO₂微纳米纤维, 即具有“微孔”、“囊泡”、“竹节”和“管”状结构的TiO₂微纳米纤维, 实现了对纤维内部结构的有效控制, 对于新型仿生中空纤维的研究具有重要意义.