考虑偏应力比影响的主应力轴旋转下重塑黄土变形研究

采用浙江大学空心圆柱扭剪仪对重塑黄土试样进行了3种复杂应力路径下的试验,研究了主应力轴旋转条件下偏应力比η对重塑黄土变形特性的影响。试验结果表明,不同偏应力比下重塑黄土的强度差异较大,η=0.133时归一化强度最小,而η=0.433时强度最大,偏应力比η从0.133到0.5时归一化强度呈现增大—减小—增大—减小的规律。主应力轴旋转对重塑黄土的各应变增量均有影响,并且对中间主应变增量的影响最大,其中大主应变和小主应变在ε-q平面内对称开展,且总体表现出Δεz0,Δεθ0的趋势,中间主应变整体呈现Δεr0的发展趋势,当应力主轴旋转目标角度α45°时,中间主应变呈现出不同的开展形式,重塑黄土在应力主轴旋转下向异性较为显著。     

滤纸法测定膨胀土总吸力试验及基质吸力预测研究

采用滤纸法测定膨胀土体吸力时,滤纸与土体表面距离不同所测得的滤纸含水率也不一样,获得的总吸力亦不相同。为此采用滤纸法开展了不同距离下的膨胀土总吸力测定试验,获得了不同距离条件下滤纸含水率的变化规律。干密度较小时,滤纸含水率随距离的增大呈现"减小-增大-减小"的规律;干密度较大时,滤纸含水率随距离的增大逐渐减小,最终趋于稳定。距离为3cm时所测得的吸力离散程度较小,可作为测定土体总吸力的标准距离。根据总吸力-距离关系式,通过引入伪基质吸力的概念,计算得到伪基质吸力,并与相应的真基质吸力进行比较。结果表明:不同干密度及含水率下的膨胀土真基质吸力与伪基质吸力之间存在良好的线性关系。此法可为测定现场土体基质吸力提供新的思路。     

Preparation and assay of C-glucosyltransferase from roots of Pueraria lobata

C-glucosyltransferase (EC 2.4.1.X) is one of the key enzymes for the biosynthesis of puerarin. This paper describes the methodology in purification and assay of the enzyme for the first time in Puerarin lobata (Wild.) Ohwi. C-glucosyltransferase from roots of P. lobata was extracted and partially purified by (NH4)2SO4 saturation. The effects of pH, temperature, and substrate concentration on the activity of the enzyme were investigated. The properties of the puerarin produced by C-glucosyltransferase were studied by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The peak activity of C-glucosyltransferase was detected in fraction of by 80% saturation of (NH4)2SO4 and the optimal conditions for enzymatic reaction were 35.5 micromol l(-1) of isoliquiritigenin and 560 micromol l(-1) of UDP-G at pH 8.1, 28 degrees C for 1 h. Mn2+ at 1 mmol l(-1) and Al3+ at 1 mmol l(-1) increased the enzyme activity, while Mg2+ inhibited its activity. The enzyme activity in Nicotiana tabacum and P. lobata were detected under the above assay conditions. Higher activity was found in roots than in leaves and stems of P. lobata, while no enzyme activity was detected in leaves of N. tabacum. It was the first time that activity of C-glucosyltransferase, which transforms isoliquiritigenin to puerarin, was detected in P. lobata.     

聚硅酸铝铁-壳聚糖复合絮凝剂的制备与应用

采用聚硅酸铝铁与壳聚糖复合,制备低成本、高絮凝性能的新型无机-有机复合絮凝剂。结果表明:最佳复合条件为pH值1.4～2.0、原料配比(质量比)1:1、最佳温度70～80℃、反应时间16h。并将该絮凝剂用于造纸废水的处理实验,在投加量每500mL为5mL时,其对废水浊度、色度和COD的去除率分别为94.5%,61.5%和78.7%。     

Biosorption of Cr(III) from aqueous solution by freeze-dried activated sludge: Equilibrium,kinetic and thermodynamic studies

Batch biosorption experiments were conducted to remove Cr(III) from aqueous solutions using activated sludge from a sewage treatment plant. An investigation was conducted on the effects of the initial pH, contact time, temperature, and initial Cr(III) concentration in the biosorption process. The results revealed that the activated sludge exhibited the highest Cr(III) uptake capacity (120 mg·g⁻¹) at 45°C, initial pH of 4, and initial Cr(III) concentration of 100 mg·L⁻¹. The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir model. The calculated thermodynamic parameters, ΔG^o (−0.8– −4.58 kJ·mol⁻¹), ΔH^o (15.6–44.4 kJ·mol⁻¹), and ΔS^o (0.06–0.15 kJ·mol⁻¹·K⁻¹) clearly indicated that the biosorption process was feasible, spontaneous, endothermic, and physical. The pseudo first-order and second-order kinetic models were adopted to describe the experimental data, which revealed that the Cr(III) biosorption process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr(III) concentration. The analysis of the values of biosorption activation energy (E_a = −7 kJ·mol⁻¹) and the intra-particle diffusion model demonstrated that Cr(III) biosorption was film-diffusion-controlled.     

Development of pretreatment protocol for DNA extraction from biofilm attached to biologic activated carbon (BAC) granules

The biologic activated carbon (BAC) process is widely used in drinking water treatments. A comprehensive molecular analysis of the microbial community structure provides very helpful data to improve the reactor performance. However, the bottleneck of deoxyribonucleic acid (DNA) extraction from BAC attached biofilm has to be solved since the conventional procedure was unsuccessful due to firm biomass attachment and adsorption capacity of the BAC granules. In this study, five pretreatments were compared, and adding skim milk followed by ultrasonic vibration was proven to be the optimal choice. This protocol was further tested using the vertical BAC samples from the full-scale biofilter of Pinghu Water Plant. The results showed the DNA yielded a range of 40 μg·g^-1 BAC (dry weight) to over 100 μg·g^-1 BAC (dry weight), which were consistent with the biomass distribution. All results suggested that the final protocol could produce qualified genomic DNA as a template from the BAC filter for downstream molecular biology researches.     

Removal of high concentrations of polycyclic aromatic hydrocarbons from contaminated soil by biodiesel

Solubilizing experiments were carried out to evaluate the ability of biodiesel to remove polycyclic aromatic hydrocarbons (PAHs) from highly contaminated manufactured gas plant (MGP) and PAHs spiked soils with hydroxypropyl-β-cyclodextrin (HPCD) and tween 80 as comparisons. Biodiesel displayed the highest solubilities of phenanthrene (420.7 mg·L^-1), pyrene (541.0 mg·L^-1), and benzo(a)pyrene (436.3 mg·L^-1). These corresponded to several fold increases relative to 10% HPCD and tween 80. Biodiesel showed a good efficiency for PAH removal from the spiked and MGP soils for both low molecular weight and high molecular weight PAHs at high concentrations. Biodiesel was the best agent for PAH removal from the spiked soils as compared with HPCD and tween 80; as over 77.9% of individual PAH were removed by biodiesel. Tween 80 also showed comparable capability with biodiesel for PAH solubilization at a concentration of 10% for the spiked soils. Biodiesel solubilized a wider range of PAHs as compared to HPCD and tween 80 for the MPG soils. At PAH concentrations of 229.6 and 996.9 mg·kg^-1, biodiesel showed obvious advantage over the 10% HPCD and tween 80, because it removed higher than 80% of total PAH. In this study, a significant difference between PAH removals from the spiked and field MGP soils was observed; PAH removals from the MGP soil by HPCD and tween 80 were much lower than those from the spiked soil. These results demonstrate that the potential for utilizing biodiesel for remediation of highly PAH-contaminated soil has been established.     

基于地理探测器的区域植被覆盖度的定量影响——以京津风沙源区为例

植被覆盖度（FVC）是衡量生态环境优秀的重要指标.本文基于MODIS NDVI数据,运用像元二分法模型,估算了2000~2018年京津风沙源区FVC,分析了其时空变化特征.在此基础上,基于地理探测器模型,定量分析了自然因素和人类活动因素等12个因子对京津风沙源区FVC空间分布的影响.结果表明,近20a来京津风沙源区FVC整体上呈增加趋势,增加率为8.2%.空间上,研究区73.7%的区域FVC在增加,其中显著增加的区域主要集中在晋北山地丘陵亚区、燕山丘陵山地水源保护亚区、大兴安岭南部亚区和科尔沁沙地亚区的南部.2000~2018年,降水是影响京津风沙源区FVC空间分布的主要自然因子,解释力为63.3%;年末大牲畜头数是影响FVC空间分布的主要人为因子,解释力为34.8%.自然因素和人类活动之间的双因子交互作用以双协同作用和非线性协同作用为主,表明相对于单因子,自然因素和人类活动间的交互作用对FVC的解释力更强.其中,降水与其他11个因子的交互作用对研究区FVC起主导作用,解释力超过60%.     

生态产品价值实现的“一村万树”绿色期权模式

随着经济的不断发展，越来越多的国家和地区开始重视绿色高质量发展，对生态产品的研究也在不断加强。各种政策工具相继出现，致力于将自然给予的生态产品资本化，并赋能经济发展。其中，衢州市柯城区的“一村万树”项目就是一种具有创新性的生态产品价值实现模式。本文对衢州市柯城区“一村万树”项目及其绿色期权模式进行研究，结合部门统计数据和空间信息数据，对“一村万树”项目实施区2018年的生态效益进行核算，并选取柯城区2010—2018年相关社会经济统计数据进行相关性分析，探析项目的社会经济效益，最后在量化分析的基础上结合公共池塘资源治理的八条设计原则，定性分析了“一村万树”绿色期权的合理性。结果显示：“一村万树”实施区2018年的生态效益为124.63亿元，约为研究区国内生产总值估算值的1.68倍，说明该项目具有巨大的生态效益；同时，相关分析结果表明该项目实施对当地第三产业的发展有较大的促进作用。柯城区“一村万树”项目以及绿色期权模式给当地带来了巨大的生态和社会经济效益，为我国的乡村绿化建设和生态产品价值实现提供了一种新范式。     

软质防弹材料的发展

近年来,软质防弹材料发展非常迅猛,本文系统地分析了软质防弹材料的防弹机理及其影响因素,提出了防弹装备设计的关注点。