人体肠道耐药基因组的研究进展

人类肠道菌群是耐药基因(antibiotic resistance genes,ARGs)的"储存库",且与人体健康密切相关。目前,抗生素的滥用严重,进一步加剧了耐药基因的传播和扩散。细菌耐药问题严重影响人体健康、食品安全和生态安全,携带耐药基因的致病菌对临床治疗造成巨大威胁。本文结合国内外研究进展,在总结人体肠道耐药基因组研究方法的基础上,探讨了肠道耐药基因的组成、来源、传播和进化,并对未来研究进行了展望,旨在促进公众对肠道耐药基因的认知,并为抗生素的合理使用提供理论支持。     

Performance of bitumen coating sheet using biomass pyrolysis oil

ABSTRACT

The “green” production of bitumen has raised increasing interest in recent years to reduce the environmental, energy-related and petro-based concerns. Bio-oil, prepared by biomass pyrolysis, can be used as a substitute for petro-based bitumen in bitumen or bitumen-based coatings, for its similar properties of good adhesion and anti-corrosion characteristics as bitumen. Although biomass is a renewable and widespread chemical resource, its high-valued utilization is still difficult. Several studies have qualitatively demonstrated the use of bio-bitumen in practical applications. The present study investigates that adding some bio-oil to traditional bitumen to form a bio-bitumen could help improve the properties of traditional bitumen. Bio-bitumen was prepared from biomass pyrolysis oil and applied to self-adhesive and doped hot-melt sheets. Results of physical properties demonstrate that bio-bitumen is a potential substitute in bitumen coating sheet.

Implications: This paper is intended to verify the effect of pyrolyzed bio-oil from wheat straw on the performance of bitumen, as well as the feasibility of application in the coating sheet. Up to now, the research on bio-bitumen is mainly in pavement bitumen. In the present research, bio-bitumen was applied to the coating sheet in different proportions. Interestingly, the prepared coating sheet exhibited higher adhesion. Other performances, such as temperature stability, mechanical strength and temperature flexibility of coating sheet showed improvement in the presence of bio-oil, which indicated the suitability of bio-oil in coating sheet bitumen.     

微库仑法测定新疆棉浆粕企业废水中可吸附有机卤素AOX

建立微库仑滴定法测定水质中可吸附有机卤素AOX的方法,考察3种活性炭柱对于空白的影响。实验结果表明,AOX的检出限为2.19μg/L,相对标准偏差为2.80%,纯水中高、中、低加标回收率在92.5%~107%,新疆棉浆粕企业废水中加标回收率为96.0%~101%。实验室空白也只有新购开封的耶拿原装活性炭小柱能满足标准要求的空白值(<30μg/L)。     

Reduced cadmium accumulation in tobacco by sodium chloride priming

Environmental Science and Pollution Research - Cadmium (Cd) pollution threatens agricultural security worldwide. This study tested the efficacy of priming chemicals to decrease Cd uptake by tobacco...     

苏南地区连续霾及重度霾的边界层气候特征

利用无锡国家基本观测站1981~2011年地面观测资料及南京、上海和杭州3个探空站的温度廓线资料,对苏南地区连续霾和重度霾的地面形势和边界层气候特征进行了分析。结果表明：苏南地区霾日地面形势主要为均压区型、高压底部或入海高压后部型、冷锋前部型、低压倒槽型和鞍型场;根据地面形势场的变化,连续9 d以上霾分4种类型,这4种类型具有不同的边界层结构变化：Ⅰ型苏南地区受两次大陆高压系统的南压（冷空气的过境）,随后分别处于均压区中,该类型逆温层底较低,中层出现逆湿区;Ⅱ型苏南地区受大陆高压底部影响,随着冷空气的南下消退,大陆高压东移入海,苏南处于均压区中,该类型主要以等温层的形势出现,高湿区主要在底层;Ⅲ型随着长江中上游低压倒槽的发展,大陆高压入海后,苏南地区处于低压倒槽顶部,随着冷空气的南下,苏南地区先后受到均压区、高压底部影响,该类型总体逆温强度较弱,逆温层厚度较薄,低层高湿区贯穿于整个连续霾日过程;Ⅳ型主要受西太平洋暖高压、东北冷涡以及西伯利亚冷空气的共同作用,苏南地区随后处于冷锋前部,待冷空气过境后苏南又位于均压区中,该类型逆温强度较强,逆温层顶有逆湿区,逆温层高度越低,地面能见度越低,逆温层强度越强,地面能见度越低;重度霾出现的地面形势主要为均压区、冷锋前部和低压倒槽,重度霾大部分过程逆温层底在近地面,由于本地污染源的排放和外地污染源的侵入,加上逆温或等温层的存在,不利于污染物的扩散,以及底层大湿区,颗粒物的吸湿增长膨大,从而降低地面能见度,形成重度霾     

Air Quality Impact of the Coal-Fired Power Plants in the Northern Passageway of the China West-East Power Transmission Project

Abstract

This paper analyzes the air quality impacts of coal-fired power plants in the northern passageway of the West-East Power Transmission Project in China. A three-layer Lagrangian model called ATMOS, was used to simulate the spatial distribution of incremental sulfur dioxide (SO₂) and coarse particulate matter (PM₁₀) concentrations under different emission control scenarios. In the year 2005, the emissions from planned power plants mainly affected the air quality of Shanxi, Shaanxi, the common boundary of Inner Mongolia and Shanxi, and the area around the boundary between Inner Mongolia and Ningxia. In these areas, the annually averaged incremental SO₂ and PM₁₀ concentrations exceed 2 and 2.5 µg/m3, respectively. The maximum increases of the annually averaged SO₂ and PM₁₀ concentrations are 8.3 and 7.2 µg/m³, respectively, which occur around Hancheng city, near the boundary of the Shaanxi and Shanxi provinces. After integrated control measures are considered, the maximum increases of annually averaged SO₂ and PM₁₀ concentrations fall to 4.9 and 4 µg/m³, respectively. In the year 2010, the areas affected by planned power plants are mainly North Shaanxi, North Ningxia, and Northwest Shanxi. The maximum increases of the annually averaged SO₂ and PM₁₀ concentrations are, respectively, 6.3 and 5.6 µg/m³, occurring in Northwest Shanxi, which decline to 4.4 and 4.1 µg/m³ after the control measures are implemented. The results showed that the proposed power plants mainly affect the air quality of the region where the power plants are built, with little impact on East China where the electricity will be used. The influences of planned power plants on air quality will be decreased greatly by implementing integrated control measures.     

改性硅藻土复合混凝剂处理深度采油废水

某油田深度采油废水中含有大量残油,粘度大、乳化程度高、油水分离困难,本实验采用改性硅藻土吸附和无机混凝剂混凝相结合以处理深度采油废水.结果表明,对于含油浓度为250～ 350 mg/L的石油废水,用强化吸附方法,吸附剂投加量为1.5 g/L,优化实验条件下除油率可达到75％;采用强化混凝的方法,PAC在投药量为200 mg/L的情况下除油率可达到87％;采用强化吸附-混凝联合处理的优化方法,投加0.7 g/L吸附剂+PAC 200 mg/L,除油率＞95％,明显高于吸附和混凝单独处理效果,大大改善了出水水质.     

三维电极法处理钻井废水影响因素分析

采取电化学法处理某钻井废水,考察了三维电极系统处理钻井废水时,废水浓度、电流密度、处理时间、电解质浓度和pH值对废水COD降解率的影响,实验结果表明,三维电极法处理钻井废水效果显著;增大电流密度、提高电解质浓度和延长处理时间能使COD去除率提高;最佳pH值为9。正交实验得到最优水平组合为A2B3C2D3E4,在此条件下COD去除率为86.56%。     

增蓝剂停留时间及对水质和浮游植物影响分析

水体遮光剂能干扰水下光照,抑制藻类生长。为了探讨水体遮光剂-增蓝剂在自然水体的作用情况,对围隔内增蓝剂的停留时间及水质、浮游藻类和沉水植物的变化特征进行分析。结果表明,当围隔水体中增蓝剂浓度为1 mg/L时,5周内其降解超过50%,9周后降解超过95%。与对照组相比,增蓝剂对围隔内总氮、总磷浓度无明显影响,易氧化成分的存在导致CODMn浓度升高至8.60 mg/L,但CODMn浓度随增蓝剂的降解逐步降至7.81 mg/L。在增蓝剂作用下水下光照度衰减明显,水深0.2 m处仅占水表面光强的21.16%,光衰减系数(k)为0.7 m-1。增蓝剂对藻类生长抑制作用明显,抑制率高达56.24%,但对金鱼藻生长无显著影响。     

Meta-analysis of the Chinese studies of the association between ambient ozone and mortality

To investigate short-term effects of ambient ozone exposure on mortality in Chinese cities, we conducted a meta-analysis of 10 effect estimates of 5 short-term studies, which reported associations between ambient ozone and mortality in Chinese mainland cities. And we estimated pooled effects by non-accidental mortality, cardiovascular mortality, and respiratory mortality. Combined estimates and their 95%CI were tested by RevMan 5, and Funnel plots were used for the bias analysis. For a 10 μg m⁻³ increase of maximum 8-h average concentration of ozone, the percent change for non-accidental mortality, cardiovascular mortality, and respiratory mortality were 0.42 (95%CI, 0.32–0.52%), 0.44% (95%CI, 0.17–0.70%) and 0.50% (95%CI, 0.22–0.77%), respectively. Compared with pooled estimates from other meta-analyses on ambient ozone-associated mortality, our pooled estimate for non-accidental mortality was slightly higher than previous ones and pooled estimate for cardiovascular mortality was consistent with others. However, we observed significantly positive association between ambient ozone and respiratory mortality, which were generally nonsignificant in earlier studies. By combining estimates from published evidence, a small but substantial association between ambient ozone level and mortality was observed in Mainland China.