Manufacture of strand board made from construction scrap wood

The objective of this research was to evaluate the physical and mechanical properties of strand board made from construction scrap wood. The strand board was manufactured using Sugi (Cryptomeria japonica D. Don) and Douglas-fir (Pseudotsuga japonica) strands selected from construction scrap wood. The strands were oriented, and three-layer (face/core/face) strand board of three types was produced: one in which the strands of the face layer were oriented at a right angle to those of the core layer (R board), another in which the strands of the face layer were oriented parallel to those of the core layer (P board), and a third in which the strands of both layers were oriented at random (Ra board). The physical and mechanical properties of the boards were evaluated based on Japanese Industrial Standard (JIS). The main results obtained are as follows: the bending strength of the strand board with a density larger than 0.55 g/cm³ exceeded the standard value of type 18 particleboard of JIS A 5908. The bending strength of the strand board was affected by board density, strand orientation and resin content, and became larger with increased density as well as resin content. That of the parallel specimen of P board was the largest among the specimen-orientations and types. The internal bond strength of the strand board with a density larger than 0.55 g/cm³ exceeded the standard value of type 18 particleboard and type 24-10 particleboard of JIS A 5908. The internal bond strength was markedly affected by the resin content of the core layer, and became larger with increased density. The thickness swelling of the strand board decreased with increased resin content, and become larger with increased density.     

衍生T形槽干气密封稳态性能研究

目的 设计具备双向旋转特点的动压型干气密封端面结构,并展现良好的开启性能,以T形槽为优化对象,衍生出一种新型槽型结构。方法 借助有限元软件,计算并对比经典T形槽与衍生槽型在流场特性和稳态性能方面的差异,探讨不同参数对2种槽型干气密封稳态性能的影响规律,揭示衍生槽型的密封机理。结果 衍生槽型的开启力高于经典T形槽,泄漏率也会增加。随着工况参数的升高,2种槽型的稳态性能参数近似线性增加,且差异逐渐增大,最小差异达到6.6%。随着槽深的增加,泄漏率方面的差距在逐渐减小,为扩大衍生槽型的控漏效果,槽深应>5μm。开设有引流槽型结构的衍生槽型稳态性能顺序为发散型>直口型>收敛型,但在文中的工况下,数值差别较小,最大仅为1.2%。结论 相比于经典T形槽,衍生槽型具有更强的动压效应,开启性能明显提升。另外,通过开设不同形式的引流槽可以改变气膜的流动特性和干气密封性能。     

Simultaneous carbon and nitrogen removal by anaerobic ammonium oxidation and denitrification under different operating strategies

Environmental Science and Pollution Research - Real domestic wastewater was treated initially in a sequencing batch reactor (SBR), with partial nitrification achieved before the effluent was used...     

Soil-air exchange of organochlorine pesticides in the Southern United States

Soil samples were collected from 30 farms in Alabama, Louisiana and Texas during 1999-2000 to determine residues of organochlorine pesticides (OCPs). One or more of the DDT compounds (p,p'-DDT, o,p'-DDT, p,p'-DDD, p,p'-DDE, o,p'-DDE) was above the quantitation limit (0.1 ng g(-1) dry weight) in every soil, and toxaphene was above the quantitation limit (3 ng g(-1)) in 26 soils. Chlordanes, dieldrin and hexachlorocyclohexane (HCH) isomers occurred less frequently (quantitation limits 0.1 ng g(-1) for dieldrin and 0.05 ng g(-1) for chlordanes and HCHs). OCPs were measured in air at 40 cm above the soil at selected farms to investigate soil-air partitioning. Concentrations of OCPs in air were positively and significantly (P<0.001-0.004) correlated to soil concentrations for toxaphene, p,p'-DDT, o,p'-DDT, p,p'-DDE, dieldrin, and trans-nonachlor. The regression was weaker (P=0.022) for cis-chlordane and not significant for trans-chlordane (P=0.43) nor gamma-HCH (P=0.80). Approach to soil-air equilibrium was assessed by calculating fugacities in the soil and air (f(s) and f(a)) for samples with quantifiable residues in both compartments. The fugacity fraction f(s)=0.5 at equilibrium and is <0.5 or >0.5 for net deposition and net volatilisation, respectively. Fugacity fractions varied greatly for different soil-air pairs, reflecting generally disequilibrium conditions. Mean fugacity fractions indicated near-equilibrium for some OCPs (p,p'-DDE, chlordanes, trans-nonachlor and dieldrin) and net volatilisation for others (p,p'-DDT, o,p'-DDT, toxaphene, gamma-HCH). Chiral analysis showed that enantioselective degradation of (+) or (-) o,p'-DDT in soil was accompanied by enrichment or depletion of the corresponding enantiomers in the overlying air, although there appeared to be some dilution by racemic o,p'-DDT from regional air transport.     

Pd-MWCNTs-泡沫镍电极对2,4-二氯苯酚的电催化加氢脱氯研究

为发展废水中氯代酚的处理技术和保护水环境安全,采用"浸渍-干燥-电沉积"法制备钯-多壁碳纳米管-泡沫镍电极,研究电极对2,4-二氯苯酚（2,4-DCP）的去除能力和动力学特征,并探讨了2,4-DCP的脱氯机理.结果表明,在MWCNTs和Pd负载量分别为0.7 mg·cm^-2和0.01 mmol·cm^-2时制备的电极对2,4-DCP去除效果最好;掺入多壁碳纳米管（MWCNTs）可增大电极的表面积,提高Pd的分散性,增强电极的催化效率.当Na₂SO₄浓度为0.05 mol·L^-1,工作电压为-1 V,反应液初始pH为7时,50 mg·L^-1的2,4-DCP降解90 min的去除率达到99.74%,降解过程符合一级反应动力学模型,速率常数为0.0667 min^-1.采用高效液相色谱法监测2,4-DCP的降解产物,发现苯酚为2,4-DCP还原的最终产物,降解途径包括直接脱去2个氯原子转化为苯酚和分步脱去2个氯原子再转化为苯酚,但以直接脱去2个氯原子为主要途径.活性基淬灭实验证明,电极通过产生的吸附态氢原子（H_ads）对2,4-DCP进行加氢脱氯.     

绿色防控技术对稻农经济收益的影响及其作用机制

中国农业正在向绿色发展转变,绿色防控技术在确保粮食安全和保护生态环境方面发挥着重要作用。文章基于四川省623户水稻种植户的微观调查数据,采用倾向得分匹配法消除了样本选择性偏差,分析了绿色防控技术对农户经济收益的影响及其作用机制,并对研究结果进行了一系列的稳健性检验。研究结果表明:①绿色防控技术的采纳能够显著改善稻农的经济收益。与未采纳绿色防控技术的状态相比,采纳绿色防控技术能够使农户每亩水稻的毛收入增加104.96%,每亩水稻的净利润增加40.45%。②从作用机制上看,采纳绿色防控技术使稻农获得了更高的市场溢价,同时有利于激励稻农扩大水稻种植规模,并增加对农地的投入,包括提高有机肥和种子的投入费用。③尽管采纳绿色防控技术带来了一定的消极影响,即提高了病虫害损失率,导致一定程度的减产,但整体而言,采纳绿色防控技术所带来的价格溢价弥补了因病虫害引致的产量损失,改善了稻农的经济收益。④绿色防控技术对稻农经济收益的影响会由于教育水平的差异以及互联网的应用而存在明显的异质性。最后,研究从加大农村人力资本投入、完善农村互联网设施、强化绿色防控技术政策支持以及加强对农用化学投入品的监管等四个方面提出对策建议。     

LCA of tomato greenhouse production using spatially differentiated life cycle impact assessment indicators: an Albanian case study

The increasing attention to agricultural exports and sustainability issues is driving a surge of interest in the life cycle assessment (LCAs) of greenhouse crop production in Albania. Meanwhile, most of the reported agricultural LCAs tend to be generic without considering regionalized environmental sensitivities. In this study, ReCiPe 2016, covering 18 midpoint indicators and 3 endpoint indicators was used to generate a full-fledged cradle-to-farm gate LCA of greenhouse tomatoes in a typical Albanian farm including spatial differentiation and indicators not covered by contemporary LCAs. The most important midpoint categories per 1 ha identified from foreground–background analysis were global warming (2660.4 kg CO2-eq), stratospheric ozone depletion (0.0308 kg CFC11-eq), particulate matter formation (7.99 kg PM2.5-eq), human health and ecosystem ozone formation (8.47 and 14.95 kg NOx-eq), water consumption (2293.23 m3), and terrestrial acidification (42.28 kg SO2-eq). The application of spatial differentiation resulted in higher impacts with about 21% for particulate matter formation, 12% for human health ozone formation, 134% for ecosystem ozone formation, 19% for terrestrial acidification, and 13% for water consumption. The impacts primarily originated from nitrogen-based fertilizer emissions and diesel fuel with the origin of the impact from nitrous oxide (N2O), ammonia volatilization (NH3), nitrogen oxides (NOx), and non-methane volatile organic compounds (NMVOCs). Water consumption was dominated by irrigation water use. Overall, at the endpoint level, 9% and 24% less cumulative damage to human health and ecosystem quality were calculated with respect to the site-generic analysis primarily from the cause-and-effect chain of water consumption (mainly lower water stress index). This affirms the importance of regional considerations in LCA calculations to reflect the impacts accordingly (i.e., the magnitude of impacts, the most relevant midpoint categories, and their relevance on endpoint level) and increase the possibility of making correct conclusions and sub-optimizations, i.e., increase the discriminating power of LCA.     

Optimal planning of co-firing alternative fuels with coal in a power plant by grey nonlinear mixed integer programming model

Energy supply and use is of fundamental importance to society. Although the interactions between energy and environment were originally local in character, they have now widened to cover regional and global issues, such as acid rain and the greenhouse effect. It is for this reason that there is a need for covering the direct and indirect economic and environmental impacts of energy acquisition, transport, production and use. In this paper, particular attention is directed to ways of resolving conflict between economic and environmental goals by encouraging a power plant to consider co-firing biomass and refuse-derived fuel (RDF) with coal simultaneously. It aims at reducing the emission level of sulfur dioxide (SO(2)) in an uncertain environment, using the power plant in Michigan City, Indiana as an example. To assess the uncertainty by a comparative way both deterministic and grey nonlinear mixed integer programming (MIP) models were developed to minimize the net operating cost with respect to possible fuel combinations. It aims at generating the optimal portfolio of alternative fuels while maintaining the same electricity generation simultaneously. To ease the solution procedure stepwise relaxation algorithm was developed for solving the grey nonlinear MIP model. Breakeven alternative fuel value can be identified in the post-optimization stage for decision-making. Research findings show that the inclusion of RDF does not exhibit comparative advantage in terms of the net cost, albeit relatively lower air pollution impact. Yet it can be sustained by a charge system, subsidy program, or emission credit as the price of coal increases over time.     

An analysis of coastal land conflict in the North of Jakarta coastal area: (A general algebraic modelling system approach)

This research was motivated by a never-ending questions, which arose in coastal land use conflict especially in Indonesian and generally in developing countries. Policy makers and others stakeholders both in central and local governments concerned with resolution conflict occurred in coastal areas. Squatters, who live and built houses in illegal land, were forced to move out to theirs origin home lands. Such conflicts occurred again and again without clear solution among parties involved. Such conflict shows that both squatters and land owners have no benefits in their conflict. Such condition could decrease their economic productivity. As a consequence the economic performance of coastal area become declining. The aim of this research is to analyse coastal land use conflict between squatters and land owners. It includes to formulate conflict resolution based on land optimation. To solve the coastal land conflicts, an economics approach is needed with assumption that conflict is a concept. As a concept, conflict could be measured by using economic variables called benefits and costs to be taken into account. GAMS (General Algebraic Modelling System) is a computer language which permit formulating economic equilibrium models as systems of nonlinear equations. In this research GAMS was used to calculate the value of land rents. The results of GAMS operation produces that the coastal land area should be maintained, expanded and added of Squatters.     

湖南省某典型流域农用地土壤重金属污染及影响因素

农田土壤环境直接关系到农产品质量安全,是维系“菜篮子”工程、保障“吃的放心”的重要基础,近年来受到广泛关注.为探明农田土壤重金属污染分布特征及主要影响因子,以污染问题突出、地势起伏较大、水网密布的我国湖南省某典型流域为研究区,以流域主干河流沿线的农田土壤为研究对象,借助单因子指数、内梅罗指数和潜在生态危害指数,综合评价土壤Cd、Hg、As、Pb、Cr这5种重金属的污染状况;结合多元统计分析与地统计分析的方法,分析土地利用类型、地形因子与重金属含量的关系,并对土壤重金属空间分布和污染来源进行探究.结果表明:①研究区土壤Cd、Hg、As、Pb、Cr的平均含量分别为1.59、0.19、33.01、229.95、72.78 mg/kg.其中,Cd、As、Pb的平均含量均超过研究区土壤背景值.②内梅罗指数分析显示,研究区中77.16%的土壤点位评价结果为重度污染;与GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准（试行）》中农用地土壤污染风险管制值相比,土壤点位中Cd、As、Pb超标现象突出,主要分布于流域上游西部;综合潜在生态危害评价结果表明,3.05%的土壤点位表现为强生态风险及以上.③不同土地利用类型中,土壤重金属含量存在显著差异.旱地、水田、果园土壤中Cd、Hg、As、Pb的含量依次降低.高程与各重金属（除Hg外）含量均呈显著相关（P < 0.05）,坡度、坡向与各重金属含量的相关性均不显著（P < 0.05）.④源解析结果表明,流域农田土壤中Cd、As、Pb受到工业生产活动、交通运输、农业活动的综合影响,Hg、Cr主要来源于成土母质等自然因素.研究显示,研究区土壤中重金属存在一定程度的污染,重金属富集受土地利用类型、高程及人为因素的影响较明显.