Coating independent cytotoxicity of citrate- and PEG-coated silver nanoparticles on a human hepatoma cell line

The antibacterial potential of silver nanoparticles(AgNPs) resulted in their increasing incorporation into consumer,industrial and biomedical products.Therefore,human and environmental exposure to AgNPs(either as an engineered product or a contaminant)supports the emergent research on the features conferring them different toxicity profiles.In this study,30 ran AgNPs coated with citrate or poly(ethylene glycol)(PEG) were used to assess the influence of coating on the effects produced on a human hepatoma cell line(HepG2),namely in terms of viability,apoptosis,apoptotic related genes,cell cycle and cyclins gene expression.Both types of coated AgNPs decreased cell proliferation and viability with a similar toxicity profile.At the concentrations used(11 and 5 μg/mL corresponding to IC50 and-IC10 levels,respectively) the amount of cells undergoing apoptosis was not significant and the apoptotic related genes BCL2(anti-apoptotic gene)and BAX(pro-apoptotic gene) were both downregulated.Moreover,both AgNPs affected HepG2 cell cycle progression at the higher concentration(11 μg/mL) by increasing the percentage of cells in S(synthesis phase) and G2(Gap 2 phase) phases.Considering the cell-cycle related genes,the expression of cyclin B1 and cyclin E1 genes were decreased.Thus,this work has shown that citrate- and PEG-coated AgNPs impact on HepG2 apoptotic gene expression,cell cycle dynamics and cyclin regulation in a similar way.More research is needed to determine the properties that confer AgNPs at lower toxicity,since their use has proved helpful in several industrial and biomedical contexts.     

基于复合语言表达的装备维修合同商评价与选择

目的科学选择最优装备维修合同商。方法提出装备维修合同商的综合评价指标,建立一种同时使用比较语言和单一语言表达的装备维修合同商选择评价模型。利用层次分析法确定指标权重,采用复合语言对备选合同商的各项指标进行评价,将复合语言转换为犹豫模糊语言术语集(HFLTS),通过有序加权平均(OWA)算子计算HFLTS的模糊包络,最后应用逼近理想点(TOPSIS)法进行了合同商的评价和选择。结果通过实例验证了该选择方法的实用性和有效性。结论为军方合理选择最优装备维修合同商提供了重要模型借鉴。     

Surface-enhanced Raman scattering of the adsorption of pesticide endosulfan on gold nanoparticles

The absorption of pesticide endosulfan on the surface of gold nanoparticles results from the formation of micrometric structures (1–10 μm) with irregular shape because of the aggregation of individual particles. Such aggregation of gold nanoparticles after absorption of pesticide shows a surface-enhanced Raman scattering (SERS) spectrum, whose intensity depends on the concentration of endosulfan. In addition, the discoloration of the colloidal solution and a diminishing of the intensity of the surface plasmon resonance absorption from individual particles were observed by UV-visible spectroscopy. At the same time, a second band between 638 and 700 nm confirms the formation of aggregates of gold nanoparticles as the concentration of endosulfan increases. Finally, we used the SERS intensity of the S?O stretching vibration at 1239 cm^?1 from the SO₃ group as a measure of concentration of pesticide endosulfan. This method could be used to estimate the level of pollution in water by endosulfan in a simple and practical form.     

Synthesis and adsorption studies of NiO nanoparticles in the presence of H2acacen ligand,for removing Rhodamine B in wastewater treatment

Cost efficient NiO nanoparticles were synthesized by hydrothermal production of nano-scale Ni(OH)₂, using Ni(NO₃)₂·6H₂O and NaOH as precursors, in the presence of H₂acacen ligand, followed by calcinations of the produced Ni(OH)₂. Prepared samples were then characterized using X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectra, Brunauer–Emmet–Teller (BET) and transmission electron microscopy (TEM). BET analysis revealed high surface area for pure nano sized NiO, averaging 176.56 m²/g and confirming its application as an efficient adsorbent. Experimental studies for Rhodamine B (RB) removal from aqueous solutions in batch systems revealed that the adsorption equilibrium was best represented by Langmuir isotherm, with the maximum monolayer capacity of 111 mg/g for RB. The kinetic data was well described by a pseudo-second-order kinetic model, having intraparticle diffusion model as a rate limiting step.     

显色法测定环境样品中的纳米二氧化钛

水环境中纳米二氧化钛分析方法的建立是研究其环境行为的基础.以钛离子与H2O2的显色反应为基础,建立了用分光光度计测定含纳米二氧化钛水样、鱼样的方法.该方法简便可行,不需要复杂仪器设备,测定结果与ICP-AES测定方法相比无显著差异.     

Effect of Nanoscale SiO<Subscript>2</Subscript> and TiO<Subscript>2</Subscript> as the Fillers on the Mechanical Properties and Aging Behavior of Linear Low-Density Polyethylene/Low-Density Polyethylene Blends

Linear low-density polyethylene (LLDPE) was blended with low-density polyethylene (LDPE) at a fixed ratio (80 wt LLDPE and 20 wt %LDPE) and filled with nanoparticles of SiO₂ and TiO₂ at a ratio up to wt 5%, so as to develop the polymeric composites suitable to preparing the agricultural micro-irrigation pipes having good environmental adaptability. These compounds were blended using calcium stearate, polyethylene wax, and titanate coupling agent as the auxiliary dispersants, and ethylene-vinyl acetate copolymer (EVA) as the toughness improver. The LLDPE/LDPE composites filled with the nanoparticles were extruded and injected to prepare the composites specimens for the performance evaluations and micro-irrigation pipe field test. The mechanical properties, thermostability, and processibility of the injected composites were investigated. The effect of heating in an oven and irradiating by ultraviolet on the mechanical properties of the composites was explored. The environmental adaptability of the micro-irrigation pipes made of the filled LLDPE/LDPE composites was evaluated making use of long-term outdoor field test in northwest China where the arid and harsh natural conditions are of great concerns. It was found that the LLDPE/LDPE blend with the LLDPE mass fraction fixed as 80% showed balanced mechanical and thermal properties and flexibility, and was suitable to be used as the basic resin matrix. The incorporation of nano-TiO₂ contributed to effectively improving the resistance to heating and ultraviolet irradiation of the composites. The composite made from 91% basic resin matrix, 6% EVA, and 3% mixed nano-SiO₂ and TiO₂, showed balanced comprehensive properties. The micro-irrigation pipes made of this filled LLDPE/LDPE composite had good environmental adaptability and service behavior in a three-year field test and were suitable to be used in arid area.     

Assessing the effects of surface-bound humic acid on the phototoxicity of anatase and rutile TiO2 nanoparticles in vitro

In this study,the cytotoxicity of two different crystal phases of TiO₂ nanoparticles,with surface modification by humic acid（HA）,to Escherichia coli,was assessed.The physicochemical properties of TiO₂ nanoparticles were thoroughly characterized.Three different initial concentrations,namely 50,100,and 200 ppm,of HA were used for synthesis of HA coated TiO₂ nanoparticles（denoted as A/RHA50,A/RHA100,and A/RHA200,respectively）.Results indicate that rutile（LC50（concentration that causes 50%mortality compared the control group）=6.5）was more toxic than anatase（LC₅0=278.8）under simulated sunlight（SSL）irradiation,possibly due to an extremely narrow band gap.It is noted that HA coating increased the toxicity of anatase,but decreased that of rutile.Additionally,AHA50 and RHA50had the biggest differences compared to uncoated anatase and rutile with LC₅0of 201.9 and21.6,respectively.We then investigated the formation of reactive oxygen species（ROS）by TiO₂ nanoparticles in terms of hydroxyl radicals（OH）and superoxide anions（O₂^-）.Data suggested that O₂^- was the main ROS that accounted for the higher toxicity of rutile upon SSL irradiation.We also observed that HA coating decreased the generation of OH and O₂^- on rutile,but increased O₂^- formation on anatase.Results from TEM analysis also indicated that HA coated rutile tended to be attached to the surface of E.coli more than anatase.     

中孔分子筛AI-MCM-41催化裂解聚烯烃反应研究

采用水热合成法制备了不同硅铝比的中孔分子筛AI-MCM-41，将其应用于高密度聚乙烯（HDPE）和聚丙烯（PP）的催化裂解反应。通过改变硅铝比、反应温度和催化剂用量，对Al-MCM-41催化HDPE和PP裂解反应的规律进行了探讨，研究表明，HDPE裂解反应受硅铝比的影响较大；而对于PP裂解反应，硅铝比在一定范围内对催化剂活性的影响不明显。另外，与热裂解和HZSM-5小孔分子筛的催化裂解结果进行了比较，结果证明A1-MCM-41具有较高的催化活性和较高的液体产物收率，尤其适合于空间位阻较大的PP的催化裂解反应。     

Synthesis of nanoiron by microemulsion with Span/Tween as mixed surfactants for reduction of nitrate in water

Denitrification of nitrate in groundwater using iron nanoparticles has received increasing interest in recent years. In order to fabricate iron nanoparticles with homogeneously spherical shape and narrow size distribution, a simple and “green” method was developed to synthesize iron nanoparticles. The conventional microemulsion methods were modified by applying Span 80 and Tween 60 as mixed surfactants. The maximum content of water in the Water-in-oil (W/O) microemulsion and its appropriate forming conditions were found, and then the microemulsion system consisting of saturated Fe²⁺ solution was used to synthesize α-Fe ultrafine particles by redox reaction. The nanoparticles were characterized by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the average diameter of the particle is about 80–90 nm. The chemical activity of the obtained iron nanoparticles was studied by the denitrification experiment of nitrate. The results show that under the experimental conditions, iron removed most of the 80 mg/L nitrate within 30 min. The mass balance of nitrate reduction with nanoscale Fe indicates that endproducts are mainly ammonia. Two possible reaction pathways for nitrate reduction by nanoscale iron particles have been proposed in this work. __________ Translated from Chemical Journal of Chinese Universities, 2006, 27(4): 672–675 [译自: 高等学校化学学报]     

Immobilized reactor for rapid destruction of recalcitrant organics and inorganics in tannery wastewater

The wastewater discharged from tanneries lack biodegradability due to the presence of recalcitrant compounds at significant concentration. The focal theme of the present investigation was to use chemo-autotrophic activated carbon oxidation(CAACO) reactor, an immobilized cell reactor using chemoautotrophs for the treatment of tannery wastewater. The treatment scheme comprised of anaerobic treatment, sand filtration, and CAACO reactor, which remove COD, BOD, TOC, VFA and sulphides respectively by 86%, 95%, 81%,71% and 100%. Rice bran mesoporous activated carbon prepared indigenously and was used for immobilization of chemoautotrophs. The degradation of xenobiotic compounds by CAACO was confirmed through HPLC and FT-IR techniques.