机床采购中人机系统安全的层次分析评价

人机系统安全评价是企业机床采购过程中非常重要的一方面.本文对影响机床的人机系统安全的因素进行了分析归类,建立了人机系统安全性评价指标体系,并应用AHP法对人机系统安全性进行了评价.结合企业对各个供应商产品的单个指标的评价得分,得到供应商产品的综合得分,从而辅助企业作出科学合理的采购决策.     

微囊藻毒素在银鲫肠道中的累积及其病理学影响

银鲫(Carassius auratus),杂食性鱼类,是我国淡水主养品种之一。在富营养化湖泊中,它能以有毒微囊藻为主要食物,导致微囊藻毒素(MCs)在其组织中大量累积。为研究MCs在肠道内累积和代谢特征及其对肠道的毒性影响,分别以50和200μg MC-LReq·kg-1剂量的MCs粗提液(主要含MC-RR和MC-LR)对银鲫进行腹腔注射,并在注射后1、3、12、24、48和168 h后取样。MCs的含量用LC-MS和HPLC进行定性和定量测定,结果发现,高低两剂量组银鲫肠中MCs的含量均在注射后1 h达最大值(分别为2.8和181.4 ng·g-1DW),然后随暴露时间的延长迅速下降。相对于毒素的累积,MCs诱导的银鲫肠组织损伤具滞后性,注射后48 h内,高低两剂量组肠道的病理变化呈时间-剂量依赖性的增长,病理特征表现为肠上皮细胞排列紊乱,甚至出现坏死、溶解和脱落,杯状细胞数目显著增多,微绒毛结构破坏并伴随淋巴细胞浸润。实验结果表明,单次染毒后MCs在鲫肠道中迅速累积后降解,并造成时间-剂量依赖性组织损伤,且低剂量组的损伤是可逆的。     

Three-dimensional barricading of a predatory trap reduces predation and enhances prey capture

Animal structures come at material, energetic, time, and expression costs. Some orb-web spiders add three-dimensional barrier structures to their webs, but many do not. Predator protection is considered to be the principal benefit of adding these structures. Accordingly, it remains paradoxical why some orb-web spiders might construct the barriers while others do not. Here, we experimentally determined whether the barrier structure added to the horizontal orb web of the spider Cyrtophora moluccensis deters predators at the cost of reducing the amount of prey captured in the field. We conducted experiments by day and night to assess whether the effects vary with the time of day. We found that the three-dimensional barriers not only offered protection from predatory wasps by day but also enhanced the amount of prey captured by day and night. Moreover, the barrier structure appears particularly useful at catching moths, the largest and most energetically profitable prey that it encounters. We, therefore, concluded that reducing the energetic and time costs associated with producing and depositing extra silk threads is the principal reason why barrier structures are used intermittently among orb-web spiders.     

Study of county-level low-carbon standards in China based on carbon emissions per capita

ABSTRACT

Low-carbon development is an essential measure to combat climate change, and the establishment of low-carbon standards is an important means to achieve low-carbon development. Due to the differences in size and development level among counties of China, the applicability and fairness of county-level low-carbon standards are very important in this country. This study analyzed the trends of county-level carbon emissions in China, defined the peak value of carbon emissions per capita, summarized the characteristics of existing low-carbon standards, and proposed a fair county-level low-carbon standard based on carbon emissions per capita. The results of our analysis suggest that, under the constraints of carbon emissions reduction policies, China’s carbon emissions per capita will tend towards a stable range. Additionally, by referring to predictions results of the peak value of China’s carbon emissions per capita, it was determined that, in low-carbon development targets, China’s county-level carbon emissions per capita should be set within the range of 2–4 tons. Besides setting low-carbon standards, the Chinese government and private enterprises should develop low-carbon technologies as soon as possible and innovate management models to achieve the win–win situation of simultaneous economic growth and carbon emissions reduction.     

镉在北京褐潮土中对玉米幼苗及其根际微生物的毒性效应

通过温室盆栽实验,研究了镉在北京褐潮土中对玉米(品种郑单958)幼苗的毒性效应及其生物富集特性,并通过聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术,探讨了镉对玉米根际微生物群落结构的影响。结果表明,高浓度(>100mg·kg-1)镉对玉米幼苗的生长发育有明显的抑制作用,北京褐潮土中镉引起玉米幼苗株高下降1/2的效应浓度(EC50)为654.6mg·kg-1,引起玉米根部和地上部干质量下降1/2的EC50分别为323.6和110.2mg·kg-1,玉米幼苗地上部生物量(干质量)可作为评价重金属生态毒性的适宜终点。玉米幼苗对镉有一定的吸收累积效应,镉在玉米幼苗各组织中的浓度分布为根>茎>叶,其中根部对镉有一定的富集作用(生物富集系数BAF>1)。镉污染可引起玉米根际微生物群落结构发生改变,高浓度(1000mg·kg-1)镉可导致部分微生物种群数量减少甚至完全消失,表明镉污染可对植物幼苗、植物根际微生物以及植物-微生物之间的相互作用造成重要的干扰和威胁。     

Synergistic degradation of pyrene and volatilization of arsenic by cocultures of bacteria and a fungus

The combination of two bacteria (Bacillus sp. PY1 and Sphingomonas sp. PY2) and a fungus (Fusarium sp. PY3), isolated from contaminated soils near a coking plant, were investigated with respect to their capability to degrade pyrene and volatilize arsenic. The results showed that all strains could use pyrene and arsenic as carbon and energy sources in a basal salts medium (BSM), with the combined potential to degrade pyrene and volatilize arsenic. Bacillus sp. PY1, Sphingomonas sp. PY2 and Fusarium sp. PY3 were isolated from the consortium and were shown to degrade pyrene and volatilize arsenic independently and in combination. Fungal-bacterial coculture has shown that the most effective removal of pyrene was 96.0% and volatilized arsenic was 84.1% after incubation in liquid medium after 9 days culture, while bioremediation ability was 87.2% in contaminated soil with 100 mg·kg^-1 pyrene. The highest level of arsenic volatilization amounted to 13.9% of the initial As concentration in contaminated soil after 63 days. Therefore, a synergistic degradation system is the most effective approach to degrade pyrene and remove arsenic in contaminated soil. These findings highlight the role of these strains in the bioremediation of environments contaminated with pyrene and arsenic.     

地质灾害系统的经济弹性及其结构研究

经济弹性是降低地质灾害系统经济损失的主要方式,如果能够对其进行准确定义和精确测量,其降低灾害损失的有效性将得到进一步增强.为此,在比较区分生态、工程、组织、规划、心理等不同学科领域弹性概念基础上,结合地质灾害系统的基本构成,对其经济弹性进行了操作化定义和数学描述.进而,在描述了地质灾害系统作用过程后,指出地质灾害系统的经济弹性是一个四维结构的概念,这对于准确衡量地质灾害经济弹性,提升其效率与潜力具有重要的作用.     

内蒙古自治区地质灾害与地质环境的关系分析

地质灾害的形成受地质环境条件中多种要素的综合控制,二者之间密切相关.这些要素包括地形地貌、气象特征、植被生态、地层岩性、地质构造、岩土体类型、人类工程活动.根据内蒙古自治区内地质灾害调查工作的研究程度及区内地质灾害的自身特点,以区内已发生灾害的大量统计数据为基础,定性分析了在何种地质环境条件下,才可能发育崩塌、滑坡、泥石流、地面塌陷灾害;定量分析了地形坡度、地形高差、沟谷流域特征、降雨量在某一具体分布范围内,才容易发育某种地质灾害;同时论述了人类工程活动对地质灾害的诱发作用.     

石化污水反渗透浓水“零排放”技术

采用微滤—反渗透(RO)—蒸发—结晶工艺处理某石化企业的RO浓水,实现了RO浓水的“零排放”.试验结果表明:经加碱、微滤后,污水硬度平均减小率为98.8％,排出的滤渣平均质量分数为9.4％,减少了污水中有机物和微生物对后续RO膜的污染;微滤产水无需降低pH,可直接进入RO系统,电导率减小率可达98.0％;蒸发可将总固体质量浓度由13 290 mg/L增至172 155 mg/L,产水电导率为66 μS/cm.     

Effects of wattle extract on Microcystic aeruginosa growth and the simulated mini fresh water ecosystem

In recent years, there has been an apparent increase in the occurrence of harmful algalblooms in fresh waters. The value of applying the novel wattle extract (Acacia mimosa) to inhibitalgal growth was assessed. Our results showed that the growth of Microcystis aeruginosa was successfully repressed by the plant extract and resulted in decreased extracellular microcystin-LR production. In the experiments, it showed a very effective inhibition in the stage of exponential growth (the largest decrease in level is 47.3% of the control) especially in nonsterile conditions, and the extract can reduce 14.5-24.7% cell density of the control in the stationary stage. In outdoor experiments, the extract reduced dissolved oxygen and pH, and selectively cut down cyanobacterial cell density to one-third of the control after 36 d of treatment. Accordingly due to competitive inhibition in interspecies, other nanoalgae and small-sized aquatic animals declined, while macrozooplankton increased. Finally more large algae were eliminated and thereby the water treated was clarified and the recovery of the freshwater ecosystem was promoted. Hence, the present study suggested a new and more effective and very low ecological risk approach to reduce nuisance blooms cyanobacteria in eutrophic water