多波段激光防护塑料的研制

本文以PMMA为基质制备了多波段激光防护塑料样品,对其性能进行了测试,该样品对YAG激光有很好的防护作用,达到实用要求。     

传统的超越与反思：可持续发展普世伦理的构建

本文认为可持续发展本涉及的是普世伦理问题,可持续发展目标的实现有赖于普适伦理规范的建立。在此基础上,本文初步分析了普世伦理的前提和原则,较详细地探讨了人与自然的伦理关系。     

不唱"绿色高调"的自然之友--"自然之友"会长梁从诫接受本刊独家专访

在我国环境保护的宣传教育中,政府机构无庸置疑起到了十分重要的作用,但非政府组织的力量也同样不可轻视。特别是近些年来环保非政府组织越来越多,其作用也越来越大,我刊经常能收到像“自然之友”、“地球村”等一些环保非政府组织的活动邀请或简讯,其形式多样,也很实际。那么非政府机构作用到底如何?又是如何运作?它们在社会中遇到了哪些问题?就此笔者采访了“自然之友”会长梁从诫先生。在此,我想特别提到的是,在长达近3个小时的采访中,我们的谈话时常被梁先生剧烈的咳嗽声打断,有时不得不依靠药物来控制,并且采访是在炎热的夏季,作为记者,我也深深被梁先生这种高度的敬业精神所感动,相信在下面的对话中,读者也能感受到梁先生的极大工作热情和献身精神。     

磷肥工业含氟废液钾盐转化法生产氢氟酸的研究

用氨中磷肥工业产生的氟硅酸溶液得到氟化铵溶液,再将氟化铵溶液与氟化钾在一定的条件下反应得到氟化氢钾并挥发出氨,氟化氢钾的分解温度为400℃,将其加热分解得氟化氢气体和氟化钾,氟化氢气体可以产氢氟酸,氟化钾和氨循环使用,同时副产二氧化硅,钾盐及产物闭路循环,整个处理过程无废物排放,处理成本低。     

变频规则波输入下直斜群桩动力响应对比试验研究

通过对2×2直斜群桩结构进行振动台模型相似比设计,围绕不同频率正弦波输入下的非液化砂土与饱和砂土中群桩-承台-上部结构体系开展横向动力响应特性试验研究。结果表明:①在输入相同频率正弦波情况下,无论是直桩群还是斜桩群,其位于饱和砂土中的动力响应放大倍数均大于相应非液化砂土工况下的放大系数,且直群桩的横向动力响应比斜群桩动力响应更显著;②随着输入波频率的增加,各试验工况的承台结构动力反应系数均有所增长,直桩群和斜桩群在饱和砂土工况中的加速度和位移的放大倍数增长较非液化砂土工况明显,直群桩比斜群桩增长显著。     

碳化硅陶瓷膜管对PM_(2.5)捕集性能的实验研究

PM2.5因其粒径小、吸附能力强、输送距离远、环境危害大,同时捕集困难而成为世界各国共同关注的大气环境问题。以涂氧化铝膜的碳化硅陶瓷膜管(孔隙率28.16%,平均孔径20μm,过滤面积0.28 m2)为过滤元件,搭建了PM2.5捕集的实验装置,对膜管的过滤时间、通量与阻力降的关系以及捕集效率与时间的关系和膜污染控制方面进行了研究。结果表明:随过滤时间增加,通量逐渐减小,阻力降逐渐增大,捕集效率逐渐增大,对PM2.5捕集效率高达99.9%;对膜污染控制参数优化后反吹压强选定为0.8 MPa,反吹间隔时间为10 min,反吹时间为14 s。     

Modeled historical land use and land cover for the conterminous United States

The landscape of the conterminous United States has changed dramatically over the last 200 years, with agricultural land use, urban expansion, forestry, and other anthropogenic activities altering land cover across vast swaths of the country. While land use and land cover (LULC) models have been developed to model potential future LULC change, few efforts have focused on recreating historical landscapes. Researchers at the US Geological Survey have used a wide range of historical data sources and a spatially explicit modeling framework to model spatially explicit historical LULC change in the conterminous United States from 1992 back to 1938. Annual LULC maps were produced at 250-m resolution, with 14 LULC classes. Assessment of model results showed good agreement with trends and spatial patterns in historical data sources such as the Census of Agriculture and historical housing density data, although comparison with historical data is complicated by definitional and methodological differences. The completion of this dataset allows researchers to assess historical LULC impacts on a range of ecological processes.     

Historical processes constrain patterns in global diatom diversity

There is a long-standing belief that microbial organisms have unlimited dispersal capabilities, are therefore ubiquitous, and show weak or absent latitudinal diversity gradients. In contrast, using a global freshwater diatom data set, we show that latitudinal gradients in local and regional genus richness are present and highly asymmetric between both hemispheres. Patterns in regional richness are explained by the degree of isolation of lake districts, while the number of locally coexisting diatom genera is highly constrained by the size of the regional diatom pool, habitat availability, and the connectivity between habitats within lake districts. At regional to global scales, historical factors explain significantly more of the observed geographic patterns in genus richness than do contemporary environmental conditions. Together, these results stress the importance of dispersal and migration in structuring diatom communities at regional to global scales. Our results are consistent with predictions from the theory of island biogeography and metacommunity concepts and likely underlie the strong provinciality and endemism observed in the relatively isolated diatom floras in the Southern Hemisphere.     

柴油机排放颗粒物净化技术研究进展

柴油机被认为是城市大气微粒的主要污染源。柴油机颗粒物组成复杂并且颗粒粒径甚小,大都属于亚微米级粒子和纳米级粒子。因而柴油机颗粒物对人类健康和大气环境的影响受到世人的广泛关注。本文主要对柴油机排放颗粒物的生成机理、化学组成及危害、物理性质、检测方法和净化技术等方面进行综述与探讨。     

Groundwater flow, multicomponent transport and biogeochemistry: development and application of a coupled process model

A research tool for modeling the reactive flow and transport of groundwater contaminants in multiple dimensions is presented. Arbitrarily complex coupled kinetic–equilibrium heterogeneous reaction networks, automatic code generation, transfer-function based solutions, parameter estimation, high-resolution methods for advection, and robust solvers for the mixed kinetic–equilibrium chemistry are some of the features of reactive flow and transport (RAFT) that make it a versatile research tool in the modeling of a wide variety of laboratory and field experiments. The treatment of reactions is quite general so that RAFT can be used to model biological, adsorption/desorption, complexation, and mineral dissolution/precipitation reactions among others. The integrated framework involving automated code generation and parameter estimation allows for the development, characterization, and evaluation of mechanistic process models. The model is described and used to solve a problem in competitive adsorption that illustrates some of these features. The model is also used to study the development of an in situ Fe(II)-zone by encouraging the growth of an iron-reducing bacterium with lactate as the electron donor. Such redox barriers are effective in sequestering groundwater contaminants such as chromate and TCE.