Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

Highly dispersed gold nanoparticles were supported on coal-based activated carbon (AC) by a sol immobilization method and were used to investigate their catalytic activity for low-level ozone decomposition at ambient temperature. Nitrogen adsorption-desorption, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts before and after ozone decomposition. The results showed that the supported gold nanoparticles prepared with microwave heating were much smaller and more uniformly dispersed on the activated carbon than those prepared with traditional conduction heating, exhibiting higher catalytic activity for ozone decomposition. The pH values of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition, and the best pH value was 8. In the case of space velocity of 120000 h⁻¹, inlet ozone concentration of 50 mg/m³, and relative humidity of 45%, the Au/AC catalyst maintained the ozone removal ratio at 90.7% after 2500 min. After being used for ozone decomposition, the surface carbon of the catalyst was partly oxidized and the oxygen content increased accordingly, while its specific surface area and pore volume only decreased a little. Ozone was mainly catalytically decomposed by the gold nanoparticles supported on the activated carbon.     

化学物质的Ah受体效应重组基因酵母检测法的优化

接有芳香烃受体(AhR)基因和芳香烃受体核转位子蛋白(ARNT)基因的酵母Saccharomyces cerevisiae菌株是测定化学物质的Ah受体效应的方法之一.本实验通过优化各个实验条件,发现用0.2%葡萄糖作前培养液培养菌24 h,用2%半乳糖作化学物质暴露时的培养液,暴露在玻璃管时,暴露时间从原来的18 h缩短到8 h.并用已经优化的方法测定了六氯苯和五氯苯的Ah受体效应,得出六氯苯和五氯苯相对于TCDD的毒性等当量值(TEF)分别为0.018629和0.000294.     

Morphology of metal nanoparticles photodeposited on TiO2/silical gel and photothermal activity for destruction of ethylene

The morphology of supported metal nanoparticles on TiO2/silical gel （TSO） and photothermal synergism were investigated for destruction of ethylene. During photocatalytic deposition of metal nanopartilces, the effects of pH and light intensity on the morphology of coated platinum, palladium, gold on TiO2/silical gel were studied. Moreover, these catalysts were characterized by TEM, UV-Vis DRS. The pH of preparing solution have strong influence on dispersion, size and sites of Pt, Pd and Au on TSO, which were controlled by the electrostatic binding of HPtCl5^- AuCl4^- and TiOH2^＋, Pd^2＋ and TiO^- respectively. Platinum, gold and palladium nanoparticles were uniformly highly dispersed on the titanol sites not silanol of TiO2/silical gel under pH=2, pH =9.9 respectively. For the photodegradation of ethylene, they show higher photothermal efficiency than those prepared with other pH conditions under UV illumination in a non-circulating photoreactor. The optimum weight loadings of Pt, Au, and Pd were 0.25 wt%, 0.5 wt%, 1 wt%, respectively. The synergistic effect enhanced ethylene removal and CO2 production. Thcse results verify that the best photothermal synergistic effect depends on the dispersion, size of noble metal nano-particles. FTIR analyses of the used Pt-, Pd-TSO catalysts indicated that no significant by-products were accumulated on the surface of the catalysts, leading to them longer lifetime.     

Intracellular biosynthesis of Au and Ag nanoparticles using ethanolic extract of Brassica oleracea L. and studies on their physicochemical and biological properties

In this present study, we reported broccoli (Brassica oleracea L.) as a potential candidate for the synthesis of gold and silver nanoparticles (NPs) in green chemistry method. The synthesized metal nanoparticles are evaluated their antimicrobial efficacy against different human pathogenic organisms. The physico-chemical properties of gold nanoparticles were analyzed using different analytical techniques such as a UV–Vis spectrophotometer, Field Emission Scanning Electron Microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and a Fourier Transform Infrared spectrophotometer. In addition, gold and silver NP antimicrobial efficacy was checked by disc diffusion assay. UV–Vis color intensity of the nanoparticles was shown at 540 and 450 nm for gold and silver nanoparticles respectively. Higher magnification of the Field Emission Scanning Electron Microscopy image shows the variable morphology of the gold nanoparticles such as spherical, rod and triangular shapes and silver nanoparticles were seen in spherical shapes. The average spherical size of the particles was observed in 24–38 nm for gold and 30–45 nm for silver NPs. X-ray diffraction pattern confirmed the presence of gold nanoparticles and silver nanoparticles which were crystalline in nature. Additionally, the functional metabolites were identified by the Fourier Transform Infrared spectroscopy. IR spectra revealed phenols, alcohols, aldehydes (sugar moieties), vitamins and proteins are present in the broccoli extract which are accountable to synthesize the nanoparticles. The synthesized gold and silver NPs inhibited the growth of the tested bacterial and fungal pathogens at the concentration of 50 μg/mL respectively. In addition, broccoli mediated gold and silver nanoparticles have shown potent antimicrobial activity against human pathogens.     

固定化酵母重复发酵性能调控

以2.5%海藻酸钠(w/v)、2%氯化钙(w/v)、2%菌体添加量(w/v,细胞干重)包埋固定酿酒酵母,通过增殖活化和批次短周期发酵对固定化粒子的发酵性能进行调控,减缓循环发酵中固定化粒子发酵性能的退化,同时利用扫描电镜(SEM)对固定化粒子的结构和酵母细胞分布情况进行表征.结果表明:调控后,固定化粒子在葡萄糖浓度为80g/L,pH 4.0,35℃的条件下发酵,发酵性能得到明显改善.调控前,连续3批次发酵,平均乙醇生产强度为0.33g/(L·h);调控后,批次发酵周期由72h缩短为24h,连续5批次发酵,平均乙醇生产强度提高至1.22g/(L·h).     

Molecular toxicity and defense mechanisms induced by silver nanoparticles in Drosophila melanogaster

The widely use of silver nanoparticles (AgNPs) as antimicrobial agents gives rise to potential environmental risks. AgNPs exposure have been reported to cause toxicity in animals. Nevertheless, the known mechanisms of AgNPs toxicity are still limited. In this study, we systematically investigated the toxicity of AgNPs exposure using Drosophila melanogaster. We show here that AgNPs significantly decreased Drosophila fecundity, the third-instar larvae weight and rates of pupation and eclosion in a dose-dependent manner. AgNPs reduced fat body cell viability in MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. AgNPs caused DNA damage in hemocytes and S2 cells. Interestingly, the mRNA levels of the entire metallothionein gene family were increased under AgNPs exposure as determined by RNA-seq analysis and validated by qRT-PCR, indicating that Drosophila responded to the metal toxicity of AgNPs by producing metallothioneins for detoxification. These findings provide a better understanding of the mechanisms of AgNPs toxicity and may provide clues to effect on other organisms, including humans.     

南京平山头铁锰帽型银(金)矿床地质特征

平山头铁锰帽型银(金)矿床位于南京栖霞山铅锌多金属矿的氧化带内，矿床特征可与长江中下游“五通组之上层状硫化物矿床的氧化铁帽”相对比。银、金矿体赋存于纵向断裂F2破碎带内，削面上可分为氧化带、混合带和原生带。银主要以硫酸盐矿物及类质同象形式存在，少量呈独立矿物辉银矿和自然银；金以显微一超显微吸附状微粒自然金存在。银与Mn、Ba、S相关．金除与As、Si有一定相关性外，一般与其它元素的相关性差。银、金表生成矿作用过程即是原生硫化物中的银、金经氧化、迁移、重新沉淀聚集的过程，银的沉淀是在SO4^2-、Fe^3 等氧化剂和H2S、Cl^-、Fe^2 、Mn^2 等还原剂作用下完成的；金主要以AuCl^2-、Au(SO4)2^3-等络合物形式迁移，并在Fe^2 、H2S等还原剂作用下沉淀。     

Au负载OMS-2催化剂的制备及其低温催化氧化性能

通过前掺杂法(QI),浸渍法(IM)和沉积-沉淀法(DP)3种方法制备了Au负载氧化锰八面体分子筛(OMS-2)Au/OMS-2催化剂,研究了制备方法和制备条件对其催化氧化CO活性的影响.采用X射线衍射(XRD)和BET比表面积测定等技术对所制样品进行表征.结果表明,沉积-沉淀法制备的Au/OMS-2-DP催化剂活性明显高于前掺杂法和浸渍法制备的催化剂,这与Au/OMS-2-DP催化剂比表面积较大和负载Au颗粒较小有关.制备条件(沉淀剂种类、制备溶液pH、Au负载量和催化剂焙烧温度)明显影响Au/OMS-2-DP催化剂的催化活性.对于各种不同的沉淀剂,以KOH为沉淀剂制备的催化剂活性最高,这可能与其无钝化作用,而且形成的Au颗粒较小有关;制备溶液的为最佳,当pH值过高或过低容易导致Au颗粒的聚集和Au沉淀量较少;XRD结果表明,当Au负载量为5wt%催化剂和催化剂焙烧为300℃时,所制备的催化剂颗粒最小,所得的催化剂活性最高.最佳条件制备的Au/OMS-2-DP催化剂活性较好,CO完全转化(100%)的温度为67℃.     

纳米金/碳纳米管修饰石墨电极测定邻苯二酚

采用自沉积方法将HAuCl4直接还原成纳米金颗粒并修饰在碳纳米管表面,所制备的纳米金(Au-CNTs/C)修饰电极对邻苯二酚(CAT)具有高的电催化氧化作用.采用循环伏安法考察CAT在Au-CNTs/C电极上的电化学行为,发现CAT在该修饰电极上发生可逆的氧化还原反应,在0.25V有明显的氧化峰.在磷酸盐缓冲溶液PBS(pH7.4)中,CAT的响应电流与浓度在5.0×10-7~5.0×10-3mol/L范围内呈线性关系,相关系数为0.9992,检出限为3.3×10-7mol/L.     

蚀变岩型金矿床地球化学新模型

以山东招远河东金矿为例，系统采集地表＋54m至－80m七个不同标高中段的地球化学样品，详细研究了包括碱性元素在内的20余种常、微量元素在蚀变岩中的分布特征，重新建立了典型蚀变岩型金矿床找矿评价的元素组合模式、物化探异常模式和地球化学分带模型，指出了深部找矿方向和探采工作应注意的问题。     

金/钴氢氧化物膜修饰玻碳电极同时测定邻苯二酚和对苯二酚

文章将纳米金与钴氢氧化物膜的催化作用有效结合,制备了GNPs/CoOOH复合修饰电极,该修饰电极在碱性条件下对邻苯二酚和对苯二酚具有较强的电催化活性。考察了支持电解质酸度及纳米金沉积时间对邻苯二酚和对苯二酚电化学响应的影响,选取0.1 mol/L PBS(pH 10.0)作为支持电解质,纳米金的最佳沉积时间为4 min。在优化的实验条件下,利用差示脉冲伏安法(DPV)对邻苯二酚和对苯二酚进行选择性检测:当两者浓度同时改变时,对苯二酚和邻苯二酚的氧化峰电流与其浓度分别在7~100μmol/L和6~100μmol/L范围内呈良好的线性关系,对应的检出限分别为0.9、0.8μmol/L(S/N=3)。该复合修饰电极具有较好的重现性、稳定性及较强的抗干扰能力。     

Effects of silica nanoparticles on growth and photosynthetic pigment contents of Scenedesmus obliquus

To assess the aquatic ecosystem safety for silica (SiO2) nanoparticles (NPs), the growth inhibition and photosynthetic pigment contents of Scenedesmus obliquus in logarithm growth phase exposed to SiO2 NPs and SiO2 bulk particles (BPs) suspensions were measured. SiO2 NPs with 10-20 nm diameters were found to be toxic. The 20% effective concentration (EC20) values for 72 and 96 hr were 388.1 and 216.5 mg/L, respectively. The contents of chlorophyll decreased significantly under moderate and high concentratio...     

Modulation of the DNA repair system and ATR-p53 mediated apoptosis is relevant for tributyltininduced genotoxic effects in human hepatoma G2 cells

The toxic effects of tributyltin (TBT) have been extensively documented in several types of cells, but the molecular mechanisms related to the genotoxic effects of TBT have still not been fully elucidated. Our study showed that exposure of human hepatoma G2 cells to 1-4 μmol/L TBT for 3 hr caused severe DNA damage in a concentration-dependent manner. Moreover, the expression levels of key DNA damage sensor genes such as the replication factor C, proliferating cell nuclear antigen and poly (ADP-ribose) polymerase-1 were inhabited in a concentration-dependent manner. We further demonstrated that TBT induced cell apoptosis via the p53-mediated pathway, which was most likely activated by the ataxia telangiectasia mutated and rad-3 related (ATR) protein kinase. The results also showed that cytochrome c, caspase-3, caspase-8, caspase-9, and the B-cell lymphoma 2 were involved in this process. Taken together, we demonstrated for the first time that the inhibition of the DNA repair system might be more responsible for TBT-induced genotoxic effects in cells. Then the generated DNA damage induced by TBT initiated ATR-p53-mediated apoptosis.     

Application of nanoparticle tracking analysis for characterising the fate of engineered nanoparticles in sediment-water systems

Novel applications of nanotechnology may lead to the release of engineered nanoparticles (ENPs), which result in concerns over their potential environmental hazardous impact. It is essential for the research workers to be able to quantitatively characterise ENPs in the environment and subsequently to assist the risk assessment of the ENPs. This study hence explored the application of nanoparticle tracking system (NTA) to quantitatively describe the behaviour of the ENPs in natural sediment-water systems. The NTA allows the measurement of both particle number concentration (PNC) and particle size distribution (PSD) of the ENPs. The developed NTA method was applied to a range of gold and magnetite ENPs with a selection of surface properties. The results showed that the positively-charged ENPs interacted more strongly with the sediment than neutral and negatively-charged ENPs. It was also found that the citrate coated Au ENPs had a higher distribution percentage (53%) than 11-mercaptoundecanoic acid coated Au ENPs (20%) and citrate coated magnetite ENPs (21%). The principles of the electrostatic interactions between hard (and soft) acids and bases (HSAB) are used to explain such behaviours; the hard base coating (i.e. citrate ions) will interact more strongly with hard acid (i.e. magnetite) than soft acid (i.e. gold). The results indicate that NTA is a complementary method to existing approaches to characterise the fate and behaviour of ENPs in natural sediment.     

Arsenate and phosphate interaction in Saccharomyces cerevisiae

In the present study, arsenate（As（V）） and phosphate（P（V）） interactions were investigated in growth, uptake and RNA content in yeast（Saccharomyces cerevisiae）. Yeast grew slowly with As（V） concentrations increasing in the medium. However, the maximal population density was almost the same among different As（V） treatments. It was in the late log phase that yeast growth was aug- mented by low As（V）, which was maybe due to the fact that methionine metabolism was stressed by vitamin B6 deprivation, so As（V） treatments did not affect maximal population density. However, with P （V） concentrations increasing, the maximal population density increased. Therefore, the maximal population density was determined by P （V） concentrations in the medium but not by As （V） concentrations in the medium. Ycflp（a tonoplast transpor） transports As（GS）3 into the vacuole, but arsenic（As） remaining in the thalli was 1.27% with As（V） exposure for 60 h, from which it can be speculated that the percentage of As transported into vacuole should be lower than 1.27%. However, the percentage of As pumped out of cell was 71.49% with As （V） exposure for 68 h. Although two pathways （extrusion and sequestration） were involved in As detoxification in yeast, the extrusion pathway played a major role in As detoxification. RNA content was the highest in the early-log phase and was reduced by As（V）.     

新疆阿克提什坎金矿床微量元素特征

阿克提什坎金矿床位于北阿尔泰诺尔特地区南缘东段 ,赋存于下石炭统红山嘴组地层中。系统地研究了该金矿床微量元素的组成特征 ,并应用等位线方法讨论了热液蚀变作用过程中微量元素的行为 ,并对微量元素在热液蚀变过程中迁移的质量进行了计算 ,研究表明在热液蚀变作用过程中 ,微量元素尤其是Au、As等元素活动强烈 ,有较大的带入和带出 ,微量元素尤其是成矿元素表现出随蚀变程度加深变化量加大的特点     

培养条件下酵母菌吸附铀的研究

研究在培养条件下对活酵母菌吸附铀的能力作了初步研究。利用偶氮胂Ⅲ作为显色剂采用分光光度法测定铀浓度的变化,结合标准曲线计算生长曲线,对酵母生长的抑制及吸附率。结果表明:酵母菌生长曲线基本符合S型生长曲线模型;低铀浓度、短培养时间时铀对酵母菌生长起促进作用,当铀浓度达到0.6mg/mL时才明显表现为抑制作用;铀浓度对吸附率的影响曲线符合典型的吸附等温线模型,随着铀浓度增大,吸附量总趋势增大;在培养条件下酵母菌对铀的处理以6～10h为佳;在低铀浓度下,铀的吸附可由Langmuir和Freundlich吸附模型模拟。     

扬子地块西北缘、西南缘超大型卡林型金矿床的找矿方向

根据扬子地块西北缘、西南缘卡林型金矿床的地质、地球化学特征 ,可以将它们划分为三种矿床地球化学类型 :Au -As-(Sb)型、Au -Hg -(Tl或U)型和Au -Sb -黄铁矿型金矿床。Au -As-(Sb)型金矿床可以成为超大型金矿床。Au -As-(Sb)型金矿床的含矿建造富含有机质、沉积成因的黄铁矿和Au、As、Sb、Fe、S等。它们属于还原环境形成的黑色沉积岩系。其构造背景是被动大陆边缘的裂谷带和裂陷沉降盆地。Au -As-(Sb)型金矿床含矿建造的干酪根是Ⅱ型干酪根 ,其原始有机母质是还原环境中形成的海相菌藻类生物演化成的腐泥型有机质。大型或超大型金矿的干酪根的元素组成显示 ,含矿流体的脱碳作用和内生氧化作用在成矿过程中具重要意义。     

制备方法条件对Au/CeO2催化CO低温氧化性能研究

用共沉淀法和沉积沉淀法制备了负载型Au/CeO2催化剂,考察了不同制备方法和条件对Au/CeO2催化剂活性的影响。结果表明,制备方法和条件对Au/CeO2催化剂的活性有较大的影响,其中以Na2CO3为沉淀剂的共沉淀法制备的Au/CeO2催化剂活性最佳。最佳制备条件:343K洗涤、473K焙烧、空气预处理。金和部分氧化态的金是活性中心,而且氧化态的金催化活性更好。活性位在金与氧化物载体界面,金粒径越小,金与氧化物载体的接触面越大,活性位越多,催化活性越大。     

„Artifizielle“ Chromosomen

The structural elements required for chromosome replication, segregation, and stability are replication origins, centromeres, and telomeres. DNA sequences capable of organizing these three elements have been isolated from yeast chromosomal DNA by means of recombinant DNA techniques and yeast cell transformation. It is now possible to combine these sequences into "artificial" chromosomes for yeast cells to obtain more insight into chromosome structure and function. Evidence is presented that the construction of artificial chromosomes functional in higher eukaryotes will be possible in the near future.