A novel investigation of tin-doped ferrihydrite nanoparticles

Tin-doped ferrihydrite was synthesized and characterized with powder X-ray diffraction and ⁵⁷Fe and ¹¹⁹Sn Mössbauer spectroscopy to obtain diagnostic and structural information. Samples were prepared with doping concentrations (molar percentages) of 0, 10, 25, 40, 50, 60, 75, and 90% tin. As Sn concentration increases, the 110 reflection plane of ferrihydrite shifts to higher d-values, while the 300 plane d-values increase, reach a maximum and then sharply drop. The δ (isomer shift) and Δ (quadrupole splitting) values for ⁵⁷Fe Mössbauer spectra increase, while the Γ (line width) values stay constant. In ¹¹⁹Sn Mössbauer spectra, δ values decrease with increasing tin substitution while Δ and Γ values increase. After 50% Sn has been substituted, the ferrihydrite becomes oversaturated with surface tin and a secondary tin structure is proposed to develop.     

Physical characteristics and properties of waterborne polyurethane materials reinforced with silk fibroin powder

Degummed silk filament was pulverized with a home‐made machine to obtain silk fibroin (SF) powder, and the structure, morphology, and particle size of the SF powder were investigated. The individual spherical particles and aggregates with different morphology of silk fibroin coexisted in water. A waterborne polyurethane (WPU) aqueous dispersion was blended with the SF powder to prepare novel blended materials with improved physical properties. The average particle size and zeta potential of the WPU/SF aqueous dispersions were characterized. The result showed that the WPU/SF dispersion with higher SF content exhibited a less negative zeta potential and a larger average particle size. Furthermore, the effect of SF content on the morphology, miscibility, and mechanical properties of the resulting blended films was studied by scanning electron microscopy, wide‐angle X‐ray diffraction, dynamic mechanical thermal analysis, and tensile testing. The films showed an improved Young's modulus and tensile strength from 0.3 to 33.8 MPa, and 0.6 to 5.2 MPa, respectively, with the increasing of SF up to a content of 26 wt %. The negative charges in the periphery and the small particle size made a good effort on dispersing SF powder into the WPU matrix as small aggregates, and the SF powder led to the efficient strengthening of WPU materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 940–950, 2010     

Ferromagnetism of Mn-doped GaN polycrystalline powders

Ferromagnetic ordering is observed in Mn-doped GaN polycrystalline powders synthesized by a modified solid-state metathesis route. The synthesized powders show hysteresis loops at 150 K. Curie temperature is about 300 K concluded from the difference between the field-cooled and zero-field-cooled magnetizations. The characterizations of the powder samples by powder X-ray diffraction, inductively coupled plasma-atomic emission spectrometry, and temperature dependence of magnetizations suggest that the room-temperature ferromagnetic ordering is the intrinsic property of Mn-doped GaN.     

ZnO粉末激光的研究

从ZnO粉末激光的实验现象出发,将激光泵浦下的ZnO粉末介质相互作用系统作为一个整体,并建立相应的物理模型。运用传输矩阵的方法数值模拟了该激光与ZnO粉末被泵浦的面积、功率和方向之间的关系。模拟结果在定性上与实验吻合。     

纳米累托石-TiO2粉末光催化降解染料废水

用纳米累托石-TiO2粉末作催化剂，在紫外灯光下降解甲基橙溶液．考察了甲基橙溶液的pH值、初始浓度、纳米累托石-TiO2投加量对甲基橙降解率的影响．比较了相同条件下制备的纳米累托石-TiO2和纳米TiO2粉末及P25TiO。粉末的光催化活性．实验结果显示：在紫外灯光照射下，纳米累托石-TiO2，纳米TiO2粉末及P25降解甲基橙30min，降解率分别为：92．9％，50．9％，96．5％．在相同条件下制备的纳米累托石-TiO2粉末比纳米TiO2粉末具有更高的催化活性，接近当今催化活性最高的P25催化剂．     

Synthesis of nanoscale reaction pits network on zerovalent iron powder surface

A neat and efficient method for controllable and reproducible synthesis of coral-shaped matrix containing abundant nanoscale reaction pits on micrometer-size zerovalent iron powder is described with the study of etching capability of dilute hydrochloric, sulfuric, and nitric acids with concentration ranges from 1 N to 6 N. Characterizations of surface morphology show that the specific surface area of this matrix increases up to 170 times that of the untreated iron powder, and that the reduction efficiency of a PCB congener in subcritical water is enhanced fivefold from 18% for the untreated iron to 92% for that with 170 times its surface area. The nanoscale pits may be a basis for enhancement of reaction cross-section via restriction of molecule mobility in the pits.     

Rheological changes in irradiated chicken eggs

Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25°C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications.     

粉体工业静电防护技术研究进展

粉体静电灾害涉及面广、危害大，开发合理的粉体静电防灾技术是国民经济发展过程中需要解决的热点问题之一．近年来，粉体静电测试研究方法、粉体静电起电与放电研究方法、粉体静电危险性评价方法、粉体静电危险性分级理论等研究工作取得了较好的研究成果．根据粉体静电现实危险性量化分析的结果而采取的粉体防静电灾害技术措施，为粉体工业生产提供了一定的安全保障．     

纤维级Mg(OH)_2超细粉的应用

天然水镁石经特殊加工制成纤维级Mg(OH) 2 超细粉 ,采用X射线衍射和扫描电子显微分析技术对其结构进行认定和分析 ,研究了它与LDPE、PVC及橡胶等复合后的阻燃作用和相容性 ,同时对共混材料的其他性能进行了分析     

CuO/Cu2(OH)3Cl的制备及其光催化降解染料光谱性能研究

以CuCl2和NaOH为原料、微波液相加热法制得CuO/Cu2(OH)3Cl粉体作为光催化剂,XRD和FTIR进行了表征.用光度分析法测定了不同光源、溶液的酸度、催化剂的用量、光照时间等条件对染料脱色率的影响.结果表明,用太阳光作为光源照射4h,溶液的酸度为pH8,CuO/Cu3(OH)3 Cl的用量为40 mg/50 mL,氨基黑、靛蓝二磺酸钠等染料脱色率达到90%以上.加入Fe3 ,H2O2等其他物质可提高染料的脱色率.通过红外光谱和紫外光谱分析,表明染料分子在催化剂和光照条件下发生了降解.