高烈度地震区隧道软硬围岩交接段刚柔并济抗减震技术研究*

为提高高烈度地震区隧道抗震性能，以某铁路隧道为研究背景，分析3种抗减震措施下隧道不同监测点隧道拱顶沉降、边墙收敛、衬砌结构PGA及最小安全系数，通过对比分析得到最优抗减震措施。结果表明:相比于工况1，工况2隧道拱顶沉降减小10.54%~81.10%，边墙收敛减小13.92%~78.77%，衬砌结构PGA减小31.42%~72.02%，最小安全系数增加18.04%~66.13%；相比于工况1，工况3结构拱顶沉降减小3.04%~18.02%，边墙收敛减小4.70%~32.00%，PGA增加13.95%~27.48%，最小安全系数增加7.49%~30.99%；工况4即“减震层+SFRC衬砌”刚柔并济法，相比于工况1，隧道拱顶沉降减小18.46%~83.98%，结构边墙收敛减小17.54%~85.47%，PGA减小30.00%~69.98%，最小安全系数增加47.95%~83.56%；4种工况抗减震性能由高到低依次为:工况4＞工况2＞工况3＞工况1。研究结果可为隧道软硬围岩交接段抗震设防提供理论参考。     

Methyl methacrylate (MMA) and alumina recovery from waste artificial marble powder pyrolysis

Journal of Material Cycles and Waste Management - Owing to various advantages of artificial marble compared to natural marble, its application has been rising exponentially, which has resulted in...     

Correction to: Preparation of GO/MIL-101(Fe,cu) composite and its adsorption mechanisms for phosphate in aqueous solution

Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-15526-6     

Study on the Balance of Agricultural Water and Land Resources on Ningxia Plain

The article puts forward the process and means of regional water and land balance research, and then from two scenarios which are the balances under natural regulation and human intervention, calculated and analysed the balance between water and land on Ningxia Plain. For the balance under natural regulation named farmland water balance, using farmland water resource balance equation, the research estimated the monthly farmland＂ water balance of 8 major crops for all of the 12 counties on Ningxia Plain in the period of 1960-2001; for the balance under human intervention, the research estimated land-use water balance equation of the counties in 2000, and calculated the balance between land use and water resources including irrigating water of all the 12 counties on Ningxia Plain. Results showed that ①precipitation can not meet the water demand of the crops for growth and development on Ningxia Plain, and water shortage is the primary character of farmland water balance under natural regulation. ②the diversity of water and land balance of different counties is distinctly influenced by the crop structure, water quantity for irrigation and irrigation level. ③Irrigation water could meet the crop water demand on Ningxia Plain in 2000, but there was not much space to expand irrigating cultivated land.     

水库沉积物贫营养型好氧反硝化菌(Pseudomonas sp.)分离及其对微污染水体脱氮效率分析

为探究深水水库沉积物微生物功能特征及利用价值,于2019年在实验室对小湾水库表层沉积物微生物进行了驯化分离,并分析了其中一株细菌的脱氮效率.结果表明,分离出的细菌XW731经鉴定属于假单胞菌属（Pseudomonas sp.）,是一种贫营养型好氧反硝化菌;在分别以NH₄⁺-N、NO₃^--N和NO₂^--N为唯一氮源时,该菌对NH₄⁺-N、NO₃^--N和NO₂^--N去除率分别为33.6%、68.5%和9.1%;以NH₄⁺-N和NO₃^--N为氮源时,对NH₄⁺-N和NO₃^--N去除率分别为66.4%、89.6%,同步硝化反硝化能力更强.将该菌投加到两种城市微污染水体后测试表明,该菌对城市河道水体的NH₄⁺-N和NO₃^--N去除率分别为38.3%和42.4%,对城市降雨水体的NH₄⁺-N和NO₃^--N去除率分别为22.2%和7.7%.     

金属改性对SAPO-34低温还原NO性能的影响

采用浸渍法制备金属改性SAPO-34分子筛催化剂,分析比较了不同单金属（Cu或Co）及不同比例双金属（Cu：Co=1：1、3：1、5：1,质量比）改性催化剂对NO的催化还原性能,评价了不同催化剂的N₂选择性,并采用扫描电子显微镜（SEM）、比表面积测试、X射线衍射分析（XRD）、NH₃-程序升温脱附（NH₃-TPD）等表征手段对催化剂的物化性能进行了分析.结果表明,单金属Cu改性催化剂具有较宽的温度区间,在250~450℃范围内NO的转化率始终保持在100%;双金属改性使NO转化率保持为100%的最低温度下降了25~50℃,显著拓宽了低温段窗口,其中,Cu₃Co₁/SAPO-34催化剂的低温催化还原性能最好,200℃即可实现100%的NO转化率,175℃下的转化率也高达80%以上.Cu-Co双金属改性SAPO-34分子筛催化剂具有优异的低温催化还原NO性能,具有在机动车尾气、工业废气的低温脱硝治理领域应用的潜力.     

Effect of NOx and SO2 on the photooxidation of methylglyoxal: Implications in secondary aerosol formation

Methylglyoxal(CH_3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3) K,atmospheric pressure,(18±2)% relative humidity,and under different NOx and SO_2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS) and the results showed that the addition of SO_2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO_2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO_2 and MG/OH/NOx/SO_2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS) and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR) analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO_2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.     

汶川地震重灾区泥石流灾损土地利用及生态修复模式——以北川县都坝河小流域为例

汶川地震诱发了大量泥石流灾害,灾损土地利用和生态修复是灾区产业重建面临的重要课题。以北川县都坝河小流域为研究对象,通过调查灾损土地禀赋、灾害特征、土地需求,采取多因素耦合和关键因子限制分析法,探讨灾害胁迫条件下的经济活动与生态修复之间的互馈作用,结果表明：（1）流域新增土地供给源主要为泥石流灾损土地,土地资源化利用受灾害、聚落和产业结构控制;（2）灾损土地根据成因划分为沟口堆积型、沟道冲淤型以及岸坡侵蚀型,三者的肥力、安全性及交通条件等特征具有显著差异;（3）基于“因灾分区、耕地优先、产业共建、美居造景”的原则,建立了灾损土地的利用方式和生态修复模式,并选取杨家沟进行验证,沟域灾损土地利用方式为生态林地、产业林地及优质耕地,分别占比28.5%、56.3%、15.2%,生态修复措施主要为提高土地安全度、提升植被覆盖率和增强水保功能。该研究建立的震区土地利用和生态修复模式可有力协调人地矛盾、发展绿色经济和提升人居环境。