巨尾桉单宁的纯化工艺及其抗氧化抑菌性能

利用NKA-9大孔树脂纯化了巨尾桉树皮和树叶中的单宁,并采用二苯基苦基肼自由基(DPPH·)和羟基自由基(·OH)的清除作用评价了其抗氧化性,采用滤纸片扩散法测定了其对5种常见食源性致病菌的抑菌作用。结果表明,在上样质量浓度0.8 g/L、上样量10 mL、体积分数80%乙醇解吸液用量为3倍柱体积(BV)的动态纯化条件下,树皮单宁纯化物中单宁的质量分数为47.82%;在上样质量浓度0.5g/L、上样量10mL、体积分数80%解吸液用量3BV的动态纯化条件下,树叶单宁纯化物中单宁的质量分数为37.00%。树皮和树叶中单宁纯化物对DPPH·的半抑制浓度(IC50)分别为0.0121和0.0168g/L;当单宁质量浓度为0.6 g/L时,对·OH的清除作用相当于V_C的2.55和2.19倍。树皮和树叶中单宁纯化物对大肠杆菌、金黄色葡萄球菌、痢疾杆菌、沙门氏菌、蜡状芽孢杆菌的抑制作用均强于粗提物,且对痢疾杆菌的抑菌圈直径分别达13.25、12.50 mm。     

Solvothermal Synthesis of Ternary Sulfides of Sb2 − x Bi x S3 (x = 0.4, 1) with 3D Flower-Like Architectures

Flower-like nanostructures of Sb_{2 − x}Bi_xS₃(x = 0.4, 1.0) were successfully prepared using both antimony diethyldithiocarbamate [Sb(DDTC)₃] and bismuth diethyldithiocarbamate [Bi(DDTC)₃] as precursors under solvothermal conditions at 180 °C. The prepared Sb_{2 − x}Bi_xS₃ with flower-like 3D architectures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The flower-like architectures, with an average diameter of ~4 μm, were composed of single-crystalline nanorods with orthorhombic structures. The optical absorption properties of the Sb_{2 − x}Bi_xS₃ nanostructures were investigated by UV–Visible spectroscopy, and the results indicate that the Sb_{2 − x}Bi_xS₃ compounds are semiconducting with direct band gaps of 1.32 and 1.30 eV for x = 0.4 and 1.0, respectively. On the basis of the experimental results, a possible growth mechanism for the flower-like Sb_{2 − x}Bi_xS₃ nanostructures is suggested.     

New scheelite-type Cd1−3x⌷xGd2x(MoO4)1−3x(WO4)3x ceramics – their structure,thermal and magnetic properties

Polycrystalline samples of scheelite-type Cd_1−3x⌷_xGd_2x(MoO₄)_1−3x(WO₄)_3x solid solution with limited homogeneity (0<x≤0.25) and cationic vacancies (denoted as ⌷) have successfully prepared by a high-temperature annealing of CdMoO₄/Gd₂(WO₄)₃ mixtures composed of 50.00 mol% and less of gadolinium tungstate. Initial reactants and obtained ceramic materials were characterized by XRD, simultaneous DTA–TG, and SEM techniques. A phase diagram of the pseudobinary CdMoO₄–Gd₂(WO₄)₃ system was constructed. The eutectic point corresponds to 1404±5 K and ~70.00 mol% of gadolinium tungstate in an initial CdMoO₄/Gd₂(WO₄)₃ mixture. With decreasing of Gd³⁺ content in a CdMoO₄ framework, the melting point of Cd_1−3x⌷_xGd_2x(MoO₄)_1−3x(WO₄)_3x increases from 1406 (x=0.25) to 1419 K (x=0.0833), and next decreases to 1408 K (x=0). EPR method was used to identify paramagnetic Gd³⁺ centers in Cd_1−3x⌷_xGd_2x(MoO₄)_1−3x(WO₄)_3x for different values of x parameter as well as to select biphasic samples containing both Cd_0.25⌷_0.25Gd_0.50(MoO₄)_0.25(WO₄)_0.75 and Gd₂(WO₄)₃.     

二元低压汽液平衡p、y、χ关系及其在加压中的近似应用

把汽液平衡的真实状态看成是3个虚拟状态的组合,结合Gibbs-Dubem方程,推得了等温低压汽液平衡时p-y-x之间的一个近似关系式,并把它推广应用到加压及含超临界组分体系的汽液平衡计算.     

二元低压汽液平衡p、y、χ关系及其在加压中的近似应用

把汽液平衡的真实状态看成是3个虚拟状态的组合,结合Gibbs-Dubem方程,推得了等温低压汽液平衡时p-y-x之间的一个近似关系式,并把它推广应用到加压及含超临界组分体系的汽液平衡计算.     

Techniques and mechanisms in electrochemistry. by P. A. Christensen & A. Hamnett,Chapman and Hall,Oxford, 1994, x + 379 pp., price £24.95. ISBN 0 7514 0129 3

A low-rank coal is examined for swelling in benzene–pyridine and toluene–pyridine mixtures. In each case, swelling is shown to mainly due to the pyridine, the action of which is specific and not amenable to interpretation by the solubility parameter approach to understanding coal swelling.     

Colloidal Synthesis of ZnS,CdS and Zn x Cd1−x S Nanoparticles from Zinc and Cadmium Thiobiuret Complexes

ZnS, CdS and Zn _x Cd_1?x S nanoparticles were synthesised from the thermolysis of 1,1,5,5-tetra-iso-propyl-4-thiobiuret complexes of Zn and/or Cd in oleylamine. The influence of the different reaction parameters (precursor concentration, growth temperature, reaction time and injection solvent/capping agent combination) on the size, morphology and optical properties of the produced nanoparticles were studied. ZnS nanoparticles with size smaller than 4.3 nm had the cubic phase whereas the particles with size larger than 4.3 nm had a hexagonal crystal structure as suggested by the selected area electron diffraction. Transmission electron microscopy showed the formation of spherical ZnS nanoparticles in addition to few ZnS nanorods only at growth temperature of 280 °C. Powder X-Ray diffraction (p-XRD) showed that the obtained CdS nanoparticles were cubic under all reaction conditions except when dodecanethiol was used as an injection solvent which produced hexagonal CdS. The change in the crystal structure of the CdS nanoparticles was accompanied with a change in morphology from spherical to triangular. Cubic Zn _x Cd_1?x S nanoparticles were obtained under all reaction conditions. Lattice spacing of the Zn _x Cd_1?x S nanoparticles showed a very good agreement with Vegard’s law. The optical properties of the Zn _x Cd_1?x S nanoparticles were highly dependent on the ZnS to CdS precursor ratio and the solvents/capping agent combinations. This in detail study on the relationship of solvent systems (capping agents), thermolysis temperatures, time of reactions and precursors will help in understanding to control the morphology, size of the crystallites and phase of the materials.