Performance of L-493 Macroprous Resin for Adsorption of Trihalomethanes from Water

Water, Air, & Soil Pollution - Microbial fuel cells (MFCs) have gained increasing attention as an effective pathway for wastewater treatment and electrical energy recovery. In this study, the...     

以树木年轮密度资料重建鄂尔多斯中部地区6至10月降水量的变化

【目的】研究鄂尔多斯中部地区未来气候环境的变化,探讨树木年轮生长与气候环境的响应关系。【方法】对鄂尔多斯中部地区油松(Pinus tabulaeformis)树木年轮样本进行了树轮密度指标的分析,结果表明,研究区树木年轮最大密度指标与树木生长期6-10月降水量有显著的正相关关系,相关系数为0.582(P>0.001)。利用油松树木年轮最大密度指数,对研究区1888年以来6-10月的降水量变化进行了重建,重建序列方差解释量为0.339。【结果】重建结果分析表明,鄂尔多斯中部地区过去115年中有明显的干湿变化特征,降水较多的湿润时段有:1888-1896年、1903-1908年、1934-1953年、1984-1993年;降水较少的干旱时段有:1897-1902年、1920-1933年、1954-1958年、1994-2000年。功率谱分析表明,重建降水量变化序列有2年、7年以及11年左右的周期变化。【结论】该地区降水变化与区域气候变化相一致,降水变化可能受大尺度气候环境变化的控制与影响。     

Evaluation of harvesting time effects on kenaf bast lignin by pyrolysis-gas chromatography

A Chinese kenaf (Hibiscus cannabinus L.), variety Sekko-ichi, was planted in May 1996, and harvested at 76, 116, 152, 185, and 226 days after planting. The hand-separated bast fibers were analyzed for lignin content and in situ lignin composition to clarify their variations with maturity. Bast fibers increased in lignin until 152 days after planting, and did not increase thereafter. Variations in in situ lignin compositions with maturity were monitored using pyrolysis-gas chromatography. The volatile pyrolysis products released at 500 °C for 4 s were identified by gas chromatography-mass spectrometry. Pyrolysis products derived from guaiacyl and syringyl lignin units were revealed. The yield of guaiacyl lignin-derived pyrolysis products decreased with maturity, while the yield of the syringyl analogous increased with maturity. The ratio of yield of syringyl lignin-derived products to that of guaiacyl ones (S/G) increased from 1.86 to 3.16 with maturity, but remained constant at 152 days after planting. High S/G ratio showed that mature bast lignin is of syringyl type. Quantitative pyrolysis results suggested that harvesting of kenaf at age of 5-months growth period provides a raw material with an ease of delignification.     

基于特征选择的黄土湿陷性预测研究

【目的】探讨视电阻率、剪切波速、导热系数及比热容等指标与黄土湿陷性的关系,从中选择可用于进行黄土湿陷性预测的指标,以简化黄土湿陷性的评价方法。【方法】在湿陷性黄土场地采取试样进行视电阻率、导热系数及比热容等试验,同时在相应取土层位进行野外剪切波速测试,运用特征选择技术,通过主成分分析、CART决策树及粒子群优化等算法对测试与试验指标进行分析。【结果】视电阻率、剪切波速在众多的测试试验指标中信息量大、重要性强,与土层埋深结合可作为黄土湿陷性的预测变量。实际工程湿陷量的预测结果表明,预测值的相对误差为-9.7%。【结论】采用视电阻率、剪切波速及土层埋深预测黄土湿陷性是可行的。     

枯草芽孢杆菌与绿萝对富营养化水体的净化

城市景观水体污染和水生态退化已经成为目前重要的环境问题。为了寻找解决景观水体富营养化的有效措施,本研究以西安市某高校校区人工湖富营养化水体为对象,利用枯草芽孢杆菌和绿萝对人工湖水体水质进行生物生态修复治理预处理实验。所有实验及指标测定方法均按照国家相关标准执行。实验结果表明,枯草芽孢杆菌和绿萝对富营养化水体均有明显的净化作用,短时间内枯草芽孢杆菌的净水效果明显优于绿萝,对明远湖总磷的去除率高达85%。将枯草芽孢杆菌和绿萝综合使用,净化修远湖和明远湖富营养化水体的效果更加显著,对水体中TN、TP、Chl-a、NH3-N、CODMn等污染质去除率均达到了80%以上。     

Farmers’ precision pesticide technology adoption and its influencing factors: Evidence from apple production areas in China

The research aimed to understand farmers’ willingness to adopt (WTA) and willingness to pay (WTP) for precision pesticide technologies and analyzed the determinants of farmers’ decision-making. We used a two-stage approach to consider farmers’ WTA and WTP for precision pesticide technologies. A survey of 545 apple farmers was administered in Bohai Bay and the Loess Plateau in China. The data were analyzed using the double-hurdle model. The results indicated that 78.72% of respondents were willing to apply precision pesticide technologies provided by service organizations such as cooperatives and dedicated enterprises, and 69.72% were willing to buy the equipment for using precision pesticide technologies. The results of the determinant analysis indicated that farmers’ perceived perceptions, farm scale, cooperative membership, access to digital information, and availability of financial services had significant and positive impacts on farmers’ WTA precision pesticide technologies. Cooperative membership, technical training, and adherence to environmental regulations increased farmers’ WTP for precision pesticide technologies. Moreover, nonlinear relationships between age, agricultural experience, and farmers’ WTA and WTP for precision pesticide technology services were found.     

Sample preparation and testing methods affect the physical properties and evaluation of plasticized zein

The objective of this research was to generate zein ribbons on an extruder in which physical property analyses can be performed to determine whether physical properties were dependent on the testing direction. The extruded zein ribbon samples had between 10 and 15% triethylene glycol (TEG) and were conditioned at relative humidities between 23 and 70% before testing to determine the impact of sample testing direction on physical properties. Tensile strengths in the machine direction were between 18 and 64% higher than in the transverse direction. Elongations in the machine direction were between 33 and 291% higher than in the transverse direction. The magnitude of the difference between the machine and transverse direction was dependent on relative humidity and formulation. The impact of relative humidity was larger when the samples were tested in the machine direction; for example, tensile strength was reduced by 36% in the transverse direction and by 49% in the machine direction for the 15% TEG formulation when relative humidity was increased from 23 to 70%. With increased amounts of TEG, the magnitude of these differences was increased. The transverse direction tensile strength was reduced by 22% for a 10% TEG formulation, and by 36% for a 15% TEG formulation when relative humidity was increased from 23 to 70%. Polarized IR spectra of zein ribbons displayed differences between the spectra taken in the machine direction versus that taken in the transverse direction. Examination of the ribbons using polarizing light microscopy demonstrated that the ribbon was birefringent (δn = 0.0004). These results demonstrate that molecular orientation occurred during extrusion and that orientation impacts physical properties.     

不同介质中石油污染物吸附过程的动力学及热力学研究

以3个不同地域的土壤为研究对象,采用平衡振荡法,研究了石油污染物在不同土壤中的吸附动力学和热力学特征。试验数据分别采用4种动力学模型进行拟合。结果表明,不同土壤对石油污染物的吸附均表现为快反应和慢反应2个阶段,0～15 min为快反应阶段,吸附量达到饱和吸附量的85%。3种土壤对石油污染物的吸附动力学符合拉格朗日假二级动力学方程。不同温度下3种供试土的吉布斯自由能变均为负值,3种土壤对石油污染物吸附过程的焓变、熵变依次为:ΔH029.11、29.12、52.70 kJ/mol;ΔS0-100.85、-103.09、-182.66 J/(mol.K)。表明,土壤对石油污染物的吸附是自发进行且为放热过程,温度升高吸附量减少,石油被吸附的过程中混乱度降低。     

多效唑对蓝茎冰草种子质量形成的影响

针对蓝茎冰草(Agropyron smithii)种子生产中因倒伏、收获期等原因造成种子质量偏低的问题,在甘肃省酒泉地区,以种植3年的蓝茎冰草为试验材料,通过喷施多效唑处理,研究种子质量的变化。结果表明,三叶期喷施多效唑(PP333)降低了蓝茎冰草种子发育后期含水量的下降速度,种子含水量从45%下降到35%对应的天数由对照的3 d提升到6~9 d,这使得种子成熟趋于一致,有效地减少了落粒损失。当PP333喷施量为2.40 kg·hm-2时,蓝茎冰草在盛花期后第42天适宜收获,此时种子干重和标准发芽率均具有最大值。