纳米氧化镍颗粒对长牡蛎(Crassostreagigas)抗氧化防御体系的影响

纳米氧化镍(nNiO)作为一种广泛使用的纳米颗粒,其水生毒理效应研究还很有限。为探索n Ni O对海洋贝类的毒性机制,本研究将长牡蛎(Crassostrea gigas)置于不同浓度(0、1、10、100 mg·L~(-1))的n Ni O中暴露96 h,分别测定鳃和消化腺组织的丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,并通过实时荧光定量PCR技术测定了鳃和消化腺中应激蛋白HSP70和AOX基因的表达变化。结果显示:在100 mg·L~(-1)n Ni O处理下,2种组织中MDA含量均显著性升高(P0.01),显示纳米颗粒造成了长牡蛎的脂质过氧化,并可能引起相应的氧化损伤。同时,n Ni O暴露也诱导了长牡蛎抗氧化酶(SOD、CAT和POD)活性的改变。其中,SOD和CAT活性在10 mg·L~(-1)浓度处理组达到最高,而POD活性在1 mg·L~(-1)浓度组即达最高值。在高浓度n Ni O(100 mg·L~(-1))胁迫下,3种抗氧化酶的活性均比低浓度(1和10 mg·L~(-1))处理组降低,表明抗氧化酶的保护作用在较低浓度暴露下更有效;而热激蛋白(hsp70)和交替氧化酶(aox)基因却分别在长牡蛎消化腺和鳃组织中上调表达(P0.01),并表现出一定的组织差异。说明高浓度纳米颗粒暴露中主要是应激蛋白发挥了作用。本文结果为纳米氧化镍对海洋双壳贝类的毒性机制研究及生态风险评估提供了基础数据。     

Potential CO2 intrusion in near-surface environments: a review of current research approaches to geochemical processes

Environmental Geochemistry and Health - Carbon dioxide (CO2) capture and storage (CCS) plays a crucial role in reducing carbon emissions to the atmosphere. However, gas leakage from deep storage...     

Seasonal variation in the occurrence of ischemic stroke: A meta-analysis

Stroke was demonstrated to correlate with seasonal variation. However, the relevant studies were incongruous. To better understand the rules of seasonal impact on ischemic stroke (IS) patients, we performed this meta-analysis. We systematically searched relevant observational studies in Pubmed, Web of science and Embase from January 1, 1980, to November 1, 2017, in English. Patients included in this study were adults who suffered from IS. Stata version 12.0 software was used to pool useful data and calculate incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). We also performed heterogeneity and sensitivity analyses and evaluated publication bias. Thirty-three observational studies involving 234,196 participants were incorporated into the meta-analysis. Summer and December were regarded as reference, respectively. The IRRs were calculated showing: IRR_Winter 1.05 (95% CI 1.04–1.07), IRR_Autumn 1.03 (95% CI 1.02–1.04), IRR_Spring 1.02 (95% CI 1.01–1.03). No obvious difference existed among 12 months. Stratified analyses on Köppen classification were also conducted. Between-study heterogeneity was discovered; however, predefined stratified analyses and meta-regression could not reduce this heterogeneity. Our meta-analysis has revealed very little seasonal variation in the overall study. Both cold and hot months may be high risky for IS after stratified by Köppen Climate Classification. Thus, a rationale to environmental setting of risky patient management could be provided. More studies with specific assessments are warranted for further comprehensive investigation.

     

钢板组合PEC柱-削弱截面钢梁组合框架抗震试验研究

为深入研究PEC柱-钢梁组合框架结构体系的抗震性能,设计了1榀两层单跨钢板组合截面PEC柱-削弱截面钢梁组合框架1∶2缩尺试件,并对其进行了低周往复荷载抗震试验。根据实测数据整理,得到了试验滞回特征曲线,并结合试验过程现象记录,分析了试件滞回特性、抗侧刚度退化规律、节点连接性能、耗能与延性和试件破坏模式等力学性能。研究结果表明:试件结构具有较高的承载力和较大的抗侧刚度;采取梁端截面削弱方式可实现梁端塑性铰位置远离节点区,且端板对穿螺栓连接能有效将梁端受拉翼缘拉力转化为对应边对节点区的压力,使得节点区形成了混凝土斜压带传力模式,提高了节点区抗震性能;试件滞回曲线较为饱满,在梁翼缘与端板连接焊缝存在施工缺陷情况下,其整体侧移、延性系数和等效黏滞阻尼比分别达到3.50%(推)/4.50%(拉)、2.92(推)/3.21(拉)和0.306,且承载力仍未下降至其极限承载力的85%,即试件结构具有良好的变形、抗震延性与耗能能力;该试件在循环往复荷载下呈现的破坏模式为梁削弱截面部位和PEC柱脚相继形成塑性铰的塑性机构。     

浅埋衬砌隧道-邻近建筑地震动力相互作用IBEM模拟

采用高精度间接边界元方法(IBEM)考察地震波入射下隧道-邻近建筑物二维地震动力相互作用的规律。结果表明:建筑物与邻近隧道存在着明显的相互作用,整体动力反应规律取决于隧道,建筑物之间的空间位置关系、隧道埋深、入射波的频率和角度等因素。隧道位于建筑物正下方时,刚性衬砌隧道(相对围岩)对上部结构主要表现为隔震效应;隧道位于建筑物两侧时,隧道对建筑顶部位移有明显放大效应,最大可放大约40%。同时隧道应力也明显增大,最大可放大约43%。因此实际中需根据隧道-建筑物的空间位置关系,适当调整衬砌隧道与沿线建筑物的抗震设防水平。     

Decontamination of Cr(VI) facilitated formation of persistent free radicals on rice husk derived biochar

PFRs were produced on biochar during Cr(VI) decontamination. PFRs formation on biochar was owing to the oxidization of phenolic-OH by Cr(VI). Appearance of excessive oxidant led to the consumption of PFRs on biochar. Biochar charred at high temperature possessed great performance to Cr(VI) removal. This study investigated the facilitation of Cr(VI) decontamination to the formation of persistent free radicals (PFRs) on rice husk derived biochar. It was found that Cr(VI) remediation by biochar facilitated the production of PFRs, which increased with the concentration of treated Cr(VI). However, excessive Cr(VI) would induce their decay. Biochar with high pyrolysis temperature possessed great performance to Cr(VI) removal, which was mainly originated from its reduction by biochar from Inductively Coupled Plasma Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy. And the corresponding generation of PFRs on biochar was primarily ascribed to the oxidization of phenolic hydroxyl groups by Cr(VI) from Fourier Transform Infrared Spectroscopy analysis, which was further verified by the H₂O₂ treatment experiments. The findings of this study will help to illustrate the transformation of reactive functional groups on biochar and provide a new insight into the role of biochar in environmental remediation.     

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of E. coli

UV can induce damages on mRNA consistently among different genes. SOS response was more active after UV treatment. Programmed cell death was not found to be more active after UV treatment. The efficacy of ultraviolet (UV) disinfection has been analyzed and validated by numerous studies using culture-based methods, yet the discovery of the viable but nonculturable state necessitates the investigation of UV disinfection based on viability parameters. Paired regulators of the SOS response system, recA-lexA, and the programmed cell death system, mazEF, in Escherichia coli were chosen as the target genes, and the effect of UV irradiation on the mRNAs of the four genes was studied. This research showed that, after UV irradiation, the responses of the mRNAs were highly consistent, with reduction percentages of approximately 60% at 20 mJ/cm², 70% at 40 mJ/cm², and 90% at 80 mJ/cm², and these reductions were believed to be the result of direct UV damage to nucleic acids. After 24 h of dark incubation, recA and lexA were both upregulated but to a lesser extent for repressor lexA; and mazE and mazF were both downregulated. This result implies that UV irradiation induces the dark repair system more actively, and the cells will proceed to death at a rate similar to that associated with natural decay.     

Do trace metal(loid)s in road soils pose health risks to tourists? A case of a highly-visited national park in China

Nowadays, more people tend to spend their recreational time in large national parks, and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health. To investigate the pollution levels, potential sources and health risks of trace metal(loid)s in road soils, a total of eight trace metal(loid)s (including As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China. The results showed that the concentrations of As, Cd, Pb, Zn and Hg appeared different degrees of pollution compared with their corresponding background values. According to the pollution indices, Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk. Combining principal component analysis and positive matrix factorization model, the results showed that traffic, industrial, agricultural and natural sources were the potential origins of trace metal(loid)s in this area, with contribution rates of 39.93%, 25.92%, 10.53% and 23.62%, respectively. Non-carcinogenic risks were all negligible, while the carcinogenic risk of As was higher than the limit (1 $\times$ 10⁻⁶). Moreover, children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation. The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults, while traffic and industrial sources have a significant impact on health risks. This study will give more insights to control the environmental risks of trace metal(loid)s in national parks.     

Contamination characteristics of trace metals in dust from different levels of roads of a heavily air-polluted city in north China

Concentrations of eight trace metals (TMs) in road dust (RD) (particles?<?25 μm) from urban areas of Xinxiang, China, were determined by inductively coupled plasma mass spectrometry. The geometric mean concentrations of Zn, Mn, Pb, As, Cu, Cr, Ni and Cd were 489, 350, 114, 101, 60.0, 39.7, 31.6, and 5.1 mg kg^?1, respectively. When compared with TM levels in background soil, the samples generally display elevated TM concentrations, except for Cr and Mn, and for Cd the enrichment value was 69.6. Spatial variations indicated TMs in RD from park path would have similar sources with main roads, collector streets and bypasses. Average daily exposure doses of the studied TMs were about three orders of magnitude higher for hand-to-mouth ingestion than dermal contact, and the exposure doses for children were 9.33 times higher than that for adults. The decreasing trend of calculated hazard indexes (HI) for the eight elements was As?>?Pb?>?Cr?>?Mn?>?Cd?>?Zn?>?Ni?>?Cu for both children and adults.     

Effects of intercropping with floricultural accumulator plants on cadmium accumulation in grapevine

Environmental Science and Pollution Research - Grapevine (Vitis vinifera L.) intercropping with floricultural cadmium (Cd) accumulator plants (Helianthus annuus L., Cosmos sulphureus Cav., Cosmos...