下穿隧道对地铁车站结构地震反应的影响研究*

针对下穿隧道对临近地铁车站地震反应的影响问题,本文采用数值模拟方法,基于 ABAQUS 平台建立了隧道下穿大开地铁车站的整体三维非线性数值分析模型,通过改变地震动类型和隧道与车站结构的交叉净距,从结构构件的破坏比和竖向变形等角度,定量分析了不同工况下隧道下穿对车站结构地震反应的影响,并与单体大开车站原型结构的地震反应进行了对比。研究表明：下穿隧道会增大地铁车站结构中柱和侧墙的破坏比(相应的最大增幅：中柱为 35%,侧墙为 26%);同时,底板的竖向变形显著增大,最大增幅达到 100%;随着交叉净距的增大, 中柱和侧墙地震反应减小,而底板竖向沉降有所增大;下穿隧道对车站结构地震反应的影响范围约为隧道直径的 3 倍。研究成果对隧道近距离穿越地铁车站结构的设计与分析具有一定的参考价值。     

“限塑令”政策有效性评估的实例分析

通过对上海市杨浦区3个居民小区"限塑令"实施前后塑料袋消费情况的调研.发现"限塑令"在一定程度上起到了塑料袋减量化的作用,但效果并不明显.其瓶颈在于我国当前对商品流通领域的控制能力非常薄弱,对非正规零售商约束力度不够、监管缺位,导致他们无视"限塑令"的规定,继续提供免费塑料袋,从而严重架空了"限塑令"的减量化效果.文章中提出了通过加强监管和处罚力度、培育社会参与机制,以及加大公众宣传活动等措施,消除"限塑令"的政策死角,以真正实现塑料购物袋消费减量化的目标.     

Repercussions of COVID-19 pandemic on solid waste generation and management strategies

• Implication of COVID-19 on medical waste and MSW generation is studied. • Challenges and effective strategy of solid waste generation is reviewed. • 2.9 million tons of COVID-19 related medical waste has been generated until Sep. 22. • The pandemic has postponed policies related to the reduction of plastic use. • Blockade resulted in a significant drop in waste generation in some regions. It has been over ten months since the beginning of the 2019 coronavirus disease (COVID-2019), and its impact on solid waste management, especially medical waste, is becoming clearer. This study systematically reviews the potential influences of the COVID-19 pandemic on medical waste, personal protection equipment waste and municipal solid waste (MSW), and discusses the corresponding measures and policies of solid waste management in typical countries. The results show that the generation of medical waste from the pandemic increased significantly, with 18%‒425% growth. It is estimated that the daily output of COVID-19 medical waste increased from 200 t/d on Feb. 22 to over 29000 t/d at the end of September 2020 throughout the world. The use of personal protective equipment will continue to grow in the long-term, while the blockade and isolation measures greatly reduced the volume of commercial waste, especially for tourist cities, and part of this waste was transferred to household waste. Residents’ attitudes and behavior toward food waste have changed due to the COVID-19 pandemic. In response to the pandemic, international organizations and several countries have issued new policies and guidelines and adjusted their management strategies for medical waste and MSW treatment. The pandemic has brought specific challenges to the disposal capacity of medical waste worldwide. It has also brought about the stagnation of policies related to the reduction of plastic products and waste recycling. This study will provide some useful information for managers and governmental officials on effective solid waste management during and after the COVID-19 pandemic.     

Droplet digital PCR is a cost-effective method for analyzing long cell-free DNA in maternal plasma: Application in preeclampsia

Objective

Long cell-free DNA (cfDNA) can be found in the plasma of pregnant women and cancer patients. We investigated if droplet digital PCR (ddPCR) can analyze such molecules for diagnostic purposes using preeclampsia as a model.

Method

Plasma samples from ten preeclamptic and sixteen normal pregnancies were analyzed. Two ddPCR assays targeting a single-copy gene, VCP, and one ddPCR assay targeting LINE-1 repetitive regions were used to measure the percentages of long cfDNA >533, 1001, and 170 bp, respectively. The LINE-1 assay was developed as guided by in silico PCR analyses to better differentiate preeclamptic and normal pregnancies.

Results

Preeclamptic patients had a significantly lower median percentage of long cfDNA than healthy pregnant controls, as determined by the LINE-1 170 bp assay (28.9% vs. 35.1%, p < 0.0001) and the VCP 533 bp assay (6.6% vs. 8.7%, p = 0.014). The LINE-1 assay provided a better differentiation than the VCP 533 bp assay (area under ROC curves, 0.94 vs. 0.79).

Conclusion

ddPCR is a cost-effective approach for unlocking diagnostic information carried by long cfDNA in plasma and may have applications for the detection of preeclampsia. Further longitudinal studies with larger cohorts are required to assess the clinical utility of this test.     

餐厨垃圾干式厌氧消化过程流变特性变化及其对反应器流场的影响

餐厨垃圾的有机组成是影响其干式厌氧消化性能的重要因素.以实际餐厨垃圾为研究对象,通过向其中投加馒头改变其有机组成,进而研究不同有机组成下物料厌氧消化过程中的流变特性变化及产甲烷特性.结果表明,不同有机组成物料的甲烷产气量与其粘度具有一定的负相关关系,表明物料流动性的提高有助于其产甲烷效率的提高.而物料流变特性的差异则主...     

生态环境监测机构数据质量技术判断常见方法探讨

环境监测数据是客观评价环境质量状况、反映污染治理成效、实施环境管理与决策的基本依据。为了进一步加强环境监测过程管理,有效提高环境监测数据质量,以列举法对影响生态环境监测机构数据质量的样品采集、运输、交接和实验室分析等监测活动的各环节进行了技术分析,梳理总结了数据质量技术判断的常见方法,旨在为环境管理部门开展监督管理提供经验借鉴。同时,就进一步提高生态环境监测机构的监测数据质量提出了建议。     

水泥窑用低氮燃烧器燃烧特性的试验研究

基于水泥生产线NO_x排放机理及控制方法,设计、研发了一种新型水泥窑用低氮燃烧器,并分析了天然气、煤制气及混合气的燃烧特性及其污染物的排放特性。结果表明:在过量空气系数α为1.2、二次风占比β为0.6时,新型低氮燃烧器燃烧天然气的效果较好,NO_x排放量为53 mg/m³,CO排放量为22 mg/m³;在相同燃烧条件下,煤制气燃烧温度及NO_x排放量比天然气高,CO排放量低于天然气;在过量空气系数α为1.2、二次风占比β为0.8时,NO_x排放量为57 mg/m³,CO排放量为6 mg/m³;天然气和煤制气掺烧时,其燃烧特性介于两者之间,且掺烧煤制气可提高天然气的燃烧速率。     

耐盐鲁氏酵母(Zygsoaccharomyces rouxii)CICC1379吸附水中重金属Cu~(2+)研究

为了研究耐盐鲁氏酵母(Zygosaccharomyces rouxii)CICC1379细胞冻干粉对重金属Cu2+的吸附作用及机理,对影响该酵母脱除水中Cu2+的主要因素(温度、初始pH和吸附时间等)进行了探讨,并对Cu2+的吸附动力学和吸附模型进行了研究.结果表明,温度(25～40℃)对耐盐鲁氏酵母粉吸附Cu2+的影响不大;初始pH(2～7)对Cu2+脱除率影响较大,最适pH值在4～6之间,而pH=2时的吸附效果较差.经耐盐鲁氏酵母处理后,溶液pH发生了变化,基本维持在4.00～6.99之间,且均趋向于相同质量氯化铜溶于水后的自然pH值(5.2).耐盐鲁氏酵母粉在5min内对Cu2+的吸附量可达到其最大吸附量的89.2%,30min可达到吸附平衡,其吸附动力学适合采用准二级动力学方程描述.与Langmuir方程相比,耐盐鲁氏酵母对Cu2+的吸附过程更适合采用Freundlich方程描述.     

内电解-水解酸化-接触氧化-氧化絮凝处理印染废水研究

采用内电解-水解酸化-接触氧化-氧化絮凝处理印染废水,考察了内电解反应中进水pH、反应时间、反应温度、鲍尔环填料中铁粉与焦炭质量比(简称Fe/C)对废水COD和色度去除效果的影响;在实验所得最佳条件下,内电解反应对废水中NH3-N和TP的去除效果;水解酸化-接触氧化对内电解出水的COD和NH3-N的去除效果及反应前后的...