Ceramic magnetic ferrite nanoribbons: Eco-friendly synthesis and their antifungal and parasiticidal activity

Ceramic nanostructures with their unique morphologies have attractive properties and various biomedical and medical applications. The production of nanoparticles (NPs) with a special morphology has been strongly influenced by lab-scale synthesis conditions and the type of reducing agents. Generally, the production of NPs with unique shapes and sizes can be adjusted by changing and optimizing the reaction mixture conditions and parameters. The formation of ceramic nanostructures during synthesis process contained the nucleation, seeding, and growth steps. By altering the kinetics and thermodynamics of synthesis process (at each stage), the shape of the produced nanostructures can be controlled. In this study, nickel ferrite ceramic nanoribbons were produced through a green and environmentally-friendly method based on the bioethical principles of preventing environmental damage, without using any other chemical composition, and only by applying plant extracts as reducing and stabilizing agents. The prepared ceramic nanoribbons were evaluated by XRD, SEM, FTIR, VSM, and HR-TEM. The results confirmed that the calcination could significantly affect the size and shape of the resulting ceramic nanostructures. The calcination could lead to the deformation of thin and hair-like ceramic nanoribbons into spherical NPs (～20 nm). Additionally, the antiparasitic properties of these nanoribbons were evaluated using MTT method, and the antifungal effects were analyzed against Aspergillus ustus. The obtained results illustrated that these nanostructures had significant toxicity against Leishmania tropica and A. ustus.     

温度/pH双响应硝化菌凝胶球的制备及特性研究

采用包埋法制备了粒径均匀的海藻酸钙(CA)硝化菌小球，并用不同浓度的NaCl溶液处理CA硝化菌小球来改善其扩散传质性能，以N-异丙基丙烯酰胺(NIPAAm)、丙烯酸(AA)为单体材料，形成温度/pH响应层，制得一种新型温度/pH双响应硝化菌凝胶小球。以NH4+?N为指示物考察不同制备条件下硝化菌凝胶小球的氨氮去除性能及对温度、pH的敏感特性，并将其应用于实际废水的脱氮处理。结果表明，经浓度为0.3%的NaCl溶液改性后的CA硝化菌小球的扩散传质性能最佳；15 mL温度响应溶液中NIPAAm为200 mg、MBA为4 mg，10 mL pH响应溶液中AA为200 mg、MBA为4 mg时双响应硝化菌小球的氨氮去除性能最好；当温度低至4℃时，氨氮去除率可达29.45%，当pH为9时，氨氮去除率仍可达35.48%。双响应硝化菌凝胶小球具有良好的温度、pH敏感特性，对实际废水中氨氮的去除也具有良好效果，有利于提高低温及碱性条件下硝化菌的硝化效果。     

Preparation of carbon fiber/Mg-doped nano-hydroxyapatite composites under low temperature by pressureless sintering

In order to protect carbon fibers (CF) from oxidation damage during sintering process, rod-like Mg-doped nano-hydroxyapatite (Mg-nHA) with an increased thermal decomposition temperature and reduced sintering temperature was synthesized by hydrothermal method. The synthesized bone-like Mg-nHA with similar composition and morphology to bone apatite was used as the matrix to prepare CF reinforced Mg-nHA composites (CF/Mg-nHA) at a low temperature of 700 °C by pressureless sintering. The increase of temperature slightly influenced the growth of Mg-nHA prepared by hydrothermal method from 160 °C to 200 °C. The Mg-nHA were short and rod-like in structure with a length of approximate 100 nm. When doping 1% magnesium, the decomposition temperature of Mg-nHA increased by 100 °C compared with that of nHA. This can protect CF from oxidation damage which is often encountered when sintering CF reinforced hydroxyapatite composites at high temperature and enhance reinforcing effects of CF. The bending strength of CF/Mg-nHA with 1 wt% CF was 8.51 MPa, which increased by 19.5% compared with Mg-nHA. Alternatively, the rod-like Mg-nHA was prepared on the surface of CF by electrochemical deposition and Mg-nHA coated CF was used to reinforce Mg-nHA, the coefficient of thermal expansion mismatch between CF and HA matrix could be mitigated. The compressive strength of Mg-nHA coated CF reinforced Mg-nHA (CF/Mg-nHA/Mg-nHA) composites with 0.5% CF sintered at 800 °C were 41.3 ± 1.56 MPa, which was attributed to the improved strengthening effect of CF and the good interface between CF and Mg-nHA matrix.     

Compatibilization and properties of ethylene vinyl acetate copolymer (EVA) and thermoplastic polyurethane (TPU) blend based foam

Ethylene vinyl acetate copolymer/thermoplastic polyurethane (EVA/TPU) blending foams are rarely reported so far because of their poor compatibility, and addition of a compatibilizer to the blend system was our major interest, which can improve interfacial adhesion between the two phases. In this paper, TPU-grafted EVA (EVA-g-TPU), as a compatibilizer, was simply prepared using maleic anhydride-grafted EVA (EVA-g-MAH) and 4,4′ diamino diphenyl methane in the mixing process of TPU and EVA matrix. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to investigate the structures of EVA-g-TPU and the interfacial reaction in the mixing process, and the effect of EVA-g-TPU on compatibilization between the two phases of EVA/TPU blends was investigated using scanning electron microscopy. Finally, EVA/EVA-g-TPU/TPU foams based on the good compatibility of the resin blends were prepared, and the physical properties directly related to the compatibility were investigated as a function of the theoretical quantity (molar mass) of EVA-g-TPU (n _EVA-g-TPU) in the foams. Moreover, the tensile strength, elongation at break, tear strength and compression set were improved by 19.0, 9.3, 43.6 and 7.5 %, respectively. Overall, EVA/EVA-g-TPU/TPU foams with excellent mechanical properties were obtained without sacrificing other important physical properties (lower density etc.) through popular and friendly means in this research.     

Ag/Bi2WO6 plasmonic composites with enhanced visible photocatalytic activity

Three-dimensional flower-like Bi₂WO₆ microspheres with the diameter of about 4 μm were prepared by a facile hydrothermal method using bismuth nitrate pentahydrate and sodium tungstate dihydrate as raw materials. A novel Ag-modified Bi₂WO₆ was synthesized through a simple and practical photoreduction process. The UV–vis diffuse reflectance spectra indicate that the Ag/Bi₂WO₆ samples have a significantly enhanced optical absorption in the visible light region than that of pure Bi₂WO₆ microspheres due to the surface plasmon resonance (SPR) of Ag nanoparticles on the surface of pure Bi₂WO₆. The photocatalytic activities of the as-prepared samples were evaluated by the decolorization of rhodamine B under simulated sun-light irradiation. The results reveal that the photocatalytic activities of the Ag/Bi₂WO₆ samples increase first and then decrease with increasing amount of loading Ag and the 1.0 wt% Ag-loaded Bi₂WO₆ sample exhibits the best photocatalytic activity compared with the other samples. The enhanced photocatalytic activity could be attributed to the synergistic effect of the strong SPR and the effective separation of photogenerated electrons and holes caused by Ag nanoparticles.     

石墨烯材料的吸附性能研究进展

石墨烯材料的吸附性能引起了国内外科学工作者的极大关注,主要介绍了近些年石墨烯和氧化石墨烯对水中金属离子、有机染料、无机非金属离子的吸附性能及研究进展。     

正交实验法优选黄连中盐酸小檗碱醇提工艺的研究

用乙醇提取黄连中盐酸小檗碱,采用正交实验法优化工艺条件.结果表明,优选的醇提工艺条件为：50％乙醇提取3次,每次提取时间1.5h,3次加醇量分别8,6,6倍.该醇提工艺重现性和稳定性良好.     

Synthesis of chemically controllable and electrically tunable graphene films by simultaneously fluorinating and reducing graphene oxide

Fluorine and oxygen co-doped graphene with controllable element coverage was effectively synthesized through simultaneously fluorinating and reducing graphene oxide by pyrolysis of fluorinated graphite. Morphology investigation indicates that the doped graphene is of few-layered thickness, and the prepared films exhibit layered structure through cross-section. Chemical composition analysis confirms that fluorine has been grafted onto graphene scaffold through CF covalent bond, and the doping level can be readily manipulated just by adjusting the reaction temperature. The structural changes of graphene induced by the controllable doping thus facilitate the tunable electrical property, which can be tuned over several orders of magnitude. These results indicate our method is not only potentially useful to tailor the chemical surface and electronic structure of graphene, but also can find applications in novel electronic devices based on graphene co-doped with different dopants.     

特低渗透油藏启动压力对油田开发的影响

特低渗透油藏由于孔喉结构的特殊性而导致流体在微小孔喉中呈现微尺度流动效应,即非达西渗流。利用岩心实验及数学模拟方法详细研究了特低渗透油藏启动压力梯度及其对油田开发的影响。研究结果表明:启动压力梯度与渗透率之间呈幂函数关系;启动压力梯度对水平井产量影响小于直井;在相同的含水饱和度下,具启动压力的油藏含水率上升较快且容易发生指进。非达西渗流将增大特低渗透油藏注水开发的难度。     

超低渗透油藏体积压裂技术研究与试验

随着低渗、超低渗油藏的开发,由于受到储层条件、注采井网、压裂工艺等多重限制,单一增加缝长来提高超低渗油藏产量效果不明显,常规压裂工艺改造难以实现该类油藏的有效开发。混合水体积压裂技术通过"大液量、高排量、低砂比"增加缝内净压力,有效扩大储层改造体积,从而提高措施增油能力,为有效提高单井产量提供了新思路、新方法。