WO3/g-C3N4异质结光催化剂的制备和光催化活性探究

采用水热合成和煅烧法制备高催化活性的WO₃/g-C₃N₄材料,并用于酸性橙G废水的降解.同时,采用X射线衍射、漫反射光谱、傅立叶变换红外光谱、扫描电镜和氮吸附-脱附测试、X光子能谱和光致发光光谱方法对复合材料进行了表征.降解实验表明,复合材料的光催化性能比单一WO₃和g-C₃N₄高,且Z型光催化剂WO₃/g-C₃N₄在WO₃与g-C₃N₄质量比为3∶10时具有最高的光催化活性,在105 min内对20 mg·L^-1酸性橙G的光降解效率达98%,反应速率是单一g-C₃N₄的5倍.采用自由基捕获剂分别对体系中的·OH、·O₂^-和h⁺进行捕获实验,结果表明,·OH、·O₂^-和h⁺共同参与了光催化降解反应,其中,h⁺是Z型WO₃/g-C₃N₄光催化的主要活性物质.复合催化剂具有良好的重复利用性,在3次循环试验后光降解效率仍达90%.     

5G对中国碳排放峰值的影响研究

基于目前5G技术的发展情况,利用holt指数平滑法和动态分析法预测了未来20年5G基站产生的直接碳排放量.根据预测模型,5G基站建设会在2038年左右达到饱和状态,数量约为1434万个.考虑到5G技术的发展推动其他产业发展可能导致的碳排放量变化,利用投入产出法和灰度时间预测法等方法评估了5G技术引起的各行业间接碳排放量.结果显示,5G基站处于低负载（30%负载）情况下,能在2038年碳排放达峰时年产生142.61Mt的直接碳排放;而如果满负荷运行,则能在2038年碳排放达峰时产生196.26Mt的直接碳排放,基于中国两种不同碳排放达峰情景,综合分析了5G技术导致的直接和间接碳排放对中国碳排放达峰时间和碳排放峰值的影响,最后对预测结果进行了稳健性检验.研究发现,实际GDP情况情景下5G技术对于社会各行业的碳排放影响在2030年达到峰值,约为255.96Mt.并且,2030年前5G技术发展对社会总体碳排放增量以间接碳排放为主,2030年后对社会碳排放增量以直接碳排放为主;综合考虑下5G技术的发展会导致中国碳排放达峰时间推后至少2年,相应的碳排放峰值至少提高了383.96Mt.若中国政府要削减5G导致的额外碳排放,完成二氧化碳总量控制,需要降低基站能耗水平,控制基站数量,避免重复建设导致5G基站低负荷运行.     

An empirical approach to determine specific weights of driving factors for the price of commodities—A contribution to the measurement of the economic scarcity of minerals and metals

In recent years, commodity markets show a large amount of volatility and substantial price jumps, indicating an increasing economic scarcity in many cases. As this scarcity makes commodity procurement a critical issue for national economies, industry sectors and manufacturing companies, a number of criticality indices have been presented and utilized in science as well as in practice. These indices are mostly based on an aggregation of different key figures, both qualitative and quantitative. However, the weighting of the different factors is in most cases arbitrary or based on rough estimates.     

植物载体固定化无花果曲霉对直接冻黄G的脱色研究

利用植物载体丝瓜瓤对无花果曲霉进行固定，并对直接冻黄G进行脱色研究。同时考察了不同因素如菌龄、温度、pH、转速对直接冻黄G的脱色影响。试验结果表明：三龄菌丝脱色效果最佳，该菌在30℃、pH6．0．90r／min的振荡条件下，经12h它对直接冻黄G的脱色达到最佳效果。固定化细胞经8次脱色后，脱色率仍达94％以上。因此用丝瓜瓤固定无花果曲霉对处理染料污染废水具有较好的应用前景。     

多级环境地理信息系统的建立

地理信息系统(GIS)是当前研究的热点,它在各类管理与决策中已被广泛采用,我国十个省市的环保局系统已建立了环境信息中心来开展这项工作。本文提出了建立既独立又能相互连接的三级环境信息系统,以适应不同层次的需要,并对各级系统的特点及其接口、汉化技术、环境数据库等进行了讨论。     

HNO_3改性活性炭对染料橙黄G的吸附研究

利用HNO_3改性后的活性炭为吸附材料,对染料橙黄G废水进行吸附处理。研究了活性炭投加量、反应时间和盐浓度对活性炭吸附橙黄G的影响,并研究了该吸附过程的吸附等温线和吸附动力学。结果显示:0~10 min是染料的快速吸附阶段,当活性炭投加量达到2.5 g/L时,40 min时橙黄G的去除率达到95.5%;高浓度盐类存在对吸附影响不明显。吸附过程符合Langmuir吸附等温方程,吸附数据可用伪二级吸附动力学方程拟合。     

Spatial distribution of hexazinone and metabolites in a luvisolic soil

Abstract

The spatial distribution of hexazinone and two primary metabolites were measured in forest soil for two years following the aerial application of a granular formulation, PRONONE 10G, in northern Alberta. Residues were quantified using solid‐phase extraction and capillary gas chromatography. Initial deposition rates of two hexazinone treatments averaged 2.3 ± 0.5 and 4.1 ± 0.8 kg/ha for each triplicated plots. One year after application, residues of hexazinone averaged 0.25 ± 0.09 and 0.40 ± 0.02 kg/ha in 2.3 and 4.1 kg/ha treatment, respectively, in the 0–10 cm surface soil; and were distributed vertically in soil depths of 0–10, 10–20, and 20–30 cm at ratios of 10:11:2 and 10:5:2, respectively, in 2.3 and 4.1 kg/ha treatment. Metabolites A and B amounted to 15 and 30% of hexazinone, respectively. Two years after application, the vertical movement of hexazinone in soil was quantifiable to the 40‐cm depth in both 2.3‐ and 4.1‐kg/ha treatment plots. Trace amounts of hexazinone were detected at 130 cm only in the 2.3‐kg/ha plot, which is likely due to the more freely downward movement of hexazinone to deeper horizons along decayed root channels.     

Effects of DDT and piperonyl butoxide on the metabolic alterations in pigeon (columba livia)

Abstract

Effect of acute doses of technical grade of dichloro diphenyl trichloro ethane (DDT) and piperonyl butoxide (PB) on hepatic micro‐somal cytochrome P₄₅₀ (Cyt. P450) and cytosolic glutathione‐S‐transferase (GST) activity in pigeon were studied after 24 hours of treatment. A completely reverse trend of changes in Cyt. P450 and GST activity were found as increase in Cyt. ?450 paralleled with decrease in GST activity following exposure to DDT. However, intensity of changes in Cyt. P450 was greater than that of GST. A dose dependent decrease in Cyt. ?450 and GST activity was observed after PB treatment. The study may, therefore, throw some light on metabolic alterations in wild birds resulting from environmental pollution by DDT and allied chemicals.     

Is gold a hedge or safe haven against oil price movements?

This paper assesses the role of gold as a hedge or safe haven against oil price movements. We use an approach based on copulas to analyse the dependence structure between these two markets. Empirical evidence for weekly data from January 2000 to September 2011 revealed the following: (a) there is positive and significant average dependence between gold and oil, which would indicate that gold cannot hedge against oil price movements; and (b) there is tail independence between the two markets, indicating that gold can act as an effective safe haven against extreme oil price movements. These results are useful for both portfolio risk managers and designers of policies aimed at using gold to preserve or stabilise oil exporter purchasing power.     

顾及空间自相关性的高分遥感影像中建设用地的变化检测

在中国城市化的进程中,建设用地常常连片分布,其开发在空间上具有明显的聚集性,表现出较强的空间自相关性,这在高空间分辨率的遥感图像中更加明显。基于2016年、2017年两期南京市域内的北京2号3.2 m多光谱遥感图像,对比分析了引入变化向量的空间自相关指数作为图像特征后建设用地遥感变化检测的性能。首先提取遥感图像光谱变化向量的局部G指数、Moran's I和Geary's C三个典型空间自相关指数,然后确定适用于变化检测的最优空间间隔（Lag）范围和最优自相关指数。结果表明：（1）光谱变化向量在空间上具有显著的正相关性。（2）全局Moran's I和半方差函数相结合可以确定最优的Lag范围。（3）在光谱变化向量的基础上加入局部G指数和局部Moran's I能够提高检测精度,F1分数表明前者优于后者。（4）在光谱变化向量的基础上加入最优Lag范围内的局部G指数作为附加图像特征,F1分数比只使用光谱变化向量提高了20%以上。融合空间自相关信息,特别是多尺度局部G指数作为遥感图像特征可有效地提高连片区域建设用地的变化检测精度。