水灰比对高温下混凝土质量损失及抗压强度影响试验研究

为研究水灰比对不同温度作用下混凝土残余抗压强度、质量损失的影响,对不同受火温度和不同水灰比的混凝土标准立方体试件进行高温下及高温后的抗压强度试验和质量损失测试。试验结果表明:随着水灰比的增大,高温下及高温后混凝土抗压强度、混凝土质量损失均呈现出整体下降的趋势。通过试验拟合回归分析,建立了高温下混凝土抗压强度、质量损失与受火温度之间的关系式,可通过质量损失、受火温度来预估高温下混凝土残余抗压强度。     

西安外商直接投资的变化特点与限制因素分析

本文通过对多年有关统计资料的计算和整理,从外商投资的阶段、资金、行业、来源及效益几个方面进行分析,表明９０年代以来,外商看好西安,西安外商直接投资的结构日趋合理。文章对西安外商投资的环境分析得出,经济规模、经济增长速率、经济开放度、基础设施是制约西安外商直接投资的主要限制因素。最后,本文提出了吸引外商直接投资的建议。     

硫酸盐还原作用对废水厌氧处理的影响

采用半连续流运行方式研究了硫酸盐还原作用对废水厌氧处理的影响。试验结果表明:当温度为35℃,pH为7.2～7.4时,进水COD/SO42-≥10,硫酸盐还原作用不致于对产甲烷菌产生严重抑制;进水COD/SO42-≥5,反应器能承受的COD负荷小于2.05kg/ (m3·d),超过这一负荷,反应器会发生严重抑制;进水COD/SO42-≥2,反应器能承受的COD负荷小于1.0kg/(m3·d)。进水COD/SO42-比值越小,反应器能承受的COD负荷越低。反应器污泥浓度高有利于硫酸盐废水的处理。      

Dissolved organic carbon, a critical factor to increase the bioavailability of phosphorus during biochar-amended aerobic composting

Considerable research efforts have been devoted to increase phosphorus（P） availability during aerobic composting.However,there is little discussion weather the dissolved organic carbon（DOC） controls the transformation among P-fractions.Thus,we investigated the changes in DOC compositions and P-fractions during biochar-amended composting（wet weight basis,5% and 10%）.TP content continuously increased since the ’concentration effect’ during aerobic composting.NaHCO₃-Pi,NaOH-Pi and HCl-Pi...     

钙对紫云英铜害的解毒作用

以南方广泛栽种的绿肥紫云英(Astragalus sinicus L.)为研究对象,尝试研究常用化学肥料中钙离子对铜离子毒害的缓解作用,为此,设计水培实验,研究了不同钙浓度(CK、2000、3 000、5 000、7000 μmol·L-1)对紫云英在铜胁迫下(50μmol·L-1)生长发育的影响.考察指标为生物量、根干质量、地上部干质量、株高、根长、结瘤情况、根色、叶色、地上部及根的铜和钙含量、根和叶中MDA含最等.以探讨钙对铜胁迫下紫云英的植株长势、对铜的吸收和转运以及膜脂过氧化作用的影响.结果表明:钙对遭受铜害的紫云英长势有促进作用,主要表现为根色转淡和生物量、株高、根长增加,而且这种作用随着培养时间的延长和钙浓度的提高愈来愈明显.进一步的分析发现,紫云英根中铜浓度和叶片MDA含量均随着钙浓度提高而显著减少,这说明钙对紫云英铜害的缓解主要是因为钙抑制了紫云英根对铜的吸收和减轻了叶片膜脂过氧化作用所致.该研究结果可为农业卜治理土壤铜污染,减轻农作物铜害的影响提供思路和科学依据.     

高大烟囱定向爆破精度影响因素分析

根据影响高大烟囱定向爆破精度的因素,对烟囱爆破切口、振动、风力及烟囱损伤、内衬、烟道口等因素进行分析,提出了一些提高定向精度的方法.     

Effect of linear alkyl benzene sulfonates (LAS) on the fate of phenanthrene in a model ecosystem (water-lava-plant-air)

Advanced closed chamber system was used to study the fate of phenanthrene (3-rings PAHs) in the presence of linear alkylbenzene sulphonates (LAS). The results showed mineralization and metabolism of phenanthrene are fast in the “culture solution-lava-plant-air“ model ecological system. The distribution proportions of applied ^14C-activity in this simulative ecological system were 41%-45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO2. Main parts of the applied ^14C-activity exist in two forms, one is polar metabolites(25%) which mainly distribute in the root(23%),the other is unextractable part (23%) which have been constructed into plant root (8.98%), shoot (0.53%) or bonded to lava(13.2%). The main metabolites of phenanthrene were polar compounels (25% of applied ^14C-activity), and small portion of ^14C-activity was identified as non-polar metabolites(6% of applied ^14C-activity) and apparent phenanthrene(1.91% of applied ^14C-activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of ^14C-activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO2 at the concentration of 200 mg/L.     

不同氧浓度下脱脂餐厨垃圾燃烧特性及动力学研究

利用热重分析法和Coats-Redfern积分法,对不同氧浓度下脱脂餐厨垃圾的燃烧特性进行研究,得到了各试样的着火温度、燃烬温度及综合燃烧特性指数,并通过燃烧动力学分析得到各试样的活化能。实验结果表明,燃烧温度从室温升至1 000℃时,脱脂餐厨垃圾燃烧过程可分为3个失重阶段:水分析出阶段、挥发分析出及燃烧阶段和固定碳燃烧阶段;随着氧浓度的升高,脱脂餐厨垃圾最大失重率以及燃烧特性指数等燃烧特性参数都有显著变化。根据Coats-Redfern积分法计算得低温和高温阶段的活化能分别为83.76~91.2 k J/mol和95.25~141.7 k J/mol。     

Emissions and distribution of methyl bromide in field beds applied at two rates and covered with two types of plastic mulches

A field experiment was conducted to compare two plastic mulches and two application rates on surface emissions and subsurface distribution of methyl bromide (MBr) in field beds in Florida. Within 30 minutes after injection of MBr to 30 cm depth, MBr had diffused upward to soil surface in all beds covered with polyethylene film (PE) or virtually impermeable film (VIF) and applied at a high rate (392 kg/ha) and a low rate (196 kg/ha). Due to the highly permeable nature of PE, within 30 minutes after injection, MBr volatilized from the bed surfaces of the two PE-covered beds into the atmosphere. The amount of volatilization was greater for the high rate-treatment bed. On the other hand, volatilization of MBr from the bed surfaces of the two VIF-covered beds were negligible. Volatilization losses occurred from the edges of all the beds covered with PE or VIF and were greater from the high rate-treatment beds. Initial vertical diffusion of MBr in the subsurface of the beds covered with PE or VIF was mainly upward, as large concentrations of MBr were detected from near bed surfaces to 20 cm depth in these beds 30 minutes after injection and little or no MBr was found at 40 cm depth. The two VIF-covered beds exhibited greater MBr concentrations and longer resident times in the root zone (0.5–40 cm depth) than corresponding PE-covered beds. Concentrations of MBr in the root zone of the high rate-treatment beds were 3.6–6.1 times larger than the low rate-treatment beds during the first days after application. In conclusion, VIF promoted retention of MBr in the root zone and, if volatilization loss from bed edges can be blocked, volatilization loss from VIF-covered beds should be negligible.     

GIS在水稻“寒露风”冷害监测预警中的应用

水稻低温冷害是广西的主要农业气象灾害,低温冷害的实时监测预警对农业趋利避害和减轻灾害损失十分重要。依托GIS技术和统计学方法,利用1∶25万的经度、纬度、海拔高度等广西基础地理信息数据,按照1 km×1 km的较高空间分辨率,对低温冷害的相关气象数据进行细网格空间分析推算,结合广西水稻生长发育状况和"寒露风"低温冷害受害指标,实现对广西水稻冷害发生发展及其强度、范围的实时监测预警,并以2010年10月上中旬冷害过程为例检验了监测效果,与冷害实际情况比较相符。