Formation of one-dimensional composites of poly(<Emphasis Type="Italic">m</Emphasis>-phenylenediamine)s based on <Emphasis Type="Italic">Streptomyces</Emphasis> for adsorption of hexavalent chromium

Here, a novel one-dimensional composite of poly(m-phenylenediamine)s coating on filamentous Streptomyces was successfully constructed via a controllable polymerization reaction. The synthesized composites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Their adsorption isotherm and kinetics for aqueous hexavalent chromium were also systematically examined. The results of scanning electron microscopy analysis indicated that the obtained composites based on Streptomyces were showed a uniform and stable one-dimensional morphology with distinct core–shell configuration. Moreover, the Langmuir isotherm model (R ² > 0.96) and pseudo-second-order equation (R ² = 0.9996) described well the equilibrium adsorption behavior and kinetics of hexavalent chromium adsorption by the composites. In addition, bath adsorption experiments demonstrated the highest adsorption capacity of hexavalent chromium by the composites reached 320.03 mg g^?1 in an acid solution, which was 5.6 times as that of the pure Streptomyces filaments. The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses suggested that the adsorption of hexavalent chromium by the composites possibly involved the protonation, redox, and chelation reactions. Therefore, a promising application of these composites in treating acid hexavalent chromium-contaminated wastewater is expectable.     

中国城市单位制研究进展

单位制是计划经济时期中国实现现代化而在城市构建的基本工具,其研究是理解历史、解读转型的重要视角,其积极因素将构成规划城市未来的重要理念.单位制研究已有30年的历史,涉及社会学、地理学、规划学等多个学科.总体而言,单位制度研究比较成熟,单位空间和社会研究在研究成果方面相对不足.单位制度起源研究有路径依赖、资源约束等视角,但确切性还不充分.单位制度形成与发展的阶段划分还未形成统一的看法.转型以来,不同类型的单位之间分化明显,不同类型的单位均有研究,但整体的判断还不明确.空间研究中,物质空间研究成果较多,但解释不足,行为空间和社会空间相对缺乏.从单位制社区向城市社区的转型得以广泛关注,但转型的路径、阶段、机理及其影响、优化策略等还有待深入探讨.     

罗氏沼虾体长和体重的一些遗传参数分析

报告了罗氏沼虾［Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉｉ（ＤｅＭａｎ）］体长和体重的一些遗传参数：在体长为１１．０４０±０．１２２（ｃｍ）、体重为４２．２５８±１．７４０（ｇ）时，雄体大于雌体。此时，体长与体重有显著的直线相关（ｒ＝０．９１２，Ｐ＜０．０１）。体重对体长的回归直线为Ｗ＝１３．０５６Ｌ—１０２．０１９，其中雌性为Ｗ＝８．３１５Ｌ—５５．３１１．雄性为Ｗ＝１６．１７ｌＬ—１３４．４０６。罗氏沼虾体长的同类相关系数为０．０４７５，体重的同类相关系数为０．０４７７１６。     

IBM-PC/XT—电视及大屏幕显示转换系统

本文介绍了使用SONY72时大屏幕投影电视和PAL-D彩色电视机作为IBM-PC/XT微机彩色显示终端转换系统功能,硬件结构及工作原理。对关键技术问题—彩色电视信号编码给出了具体电路和波形。     

大连市内部地域结构转型与郊区化

在回顾大连城市内涪地域结构形成发展的基础上,分析了８０年代以来大连城市土地利用结构的总体变化趋势,并尝试提出了大连市内部地域结构模式图。８０年代期间,大连市内部地域结构已开始由单中心集聚型向多中心集聚与扩散并存型转型,而这种转型是大连市效区化现象在城市地域上的空间反映。     

工程VSP模拟和应用问题的研究

本文对在工程地质勘查中常遇到的一些地质模型进行了ＶＳＰ正演模拟,根据正演模拟结果,讨论了在工程ＶＳＰ勘查中应注意的问题,并对工程ＶＳＰ的应用问题进行了讨论。     

Simulated biogeochemical responses to iron enrichments in three high nutrient, low chlorophyll (HNLC) regions

To fill temporal gaps in iron-enrichment experimental data and gain further understanding of marine ecosystem responses to iron enrichments, we apply a fifteen-compartment ecosystem model to three iron-enrichment sites, namely SEEDS (the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study; 48.5°N, 165°E) in the western North Pacific, SOIREE (the Southern Ocean Iron RElease Experiment; 61°S, 140°E) in the Southern Ocean, and IronExII (the second mesoscale iron enrichment experiment; 3.5°S, 104°W) in the Equatorial Pacific. The ecological effects of iron in the model are represented by changing two photosynthetic parameters during the iron-enrichment period. The model results successfully reproduce the observed biogeochemical responses inside and outside the iron patch at each site, such as rapid increases in plankton biomass and biological productivity, and decreases in surface nutrients and pCO₂, inside the patch. However, the modeled timing and magnitude of changes differ among the sites because of differences in both physical environments and plankton species. After the iron enrichment, the diatom productivity is strongly controlled by light at SOIREE and by silicate at IronExII and SEEDS. Light limitation due to self-shading by the phytoplankton is significant during the bloom at all sites. Sensitivity analysis of the model results to duration of the iron enrichment reveals that long-term multiple infusions over more than a week would not be effective at SEEDS because of strong silicate limitation on diatom growth. Sensitivity of the model to water temperature shows that export production is higher at lower temperatures, because of slower recycling of particulate organic carbon. Therefore, the e-ratio (the ratio of export production to primary production) is inversely correlated with temperature, and the relationship can be described with a linear function. Through this study, we conclude that ecosystem modeling is a powerful tool to help design future iron-enrichment experiments and observational plans.     

双齿围沙蚕Perinereis aibuhitensis繁殖的生态

本文研究了栖息于厦门杏林海区的双齿围沙蚕的繁殖习性等。结果表明,其繁殖期出现在每年2～5月,3月末至4月初为繁殖高峰期;雌雄性比为1∶1.7;卵径为186～214μm;胚胎发育经担轮幼虫、膜内疣足幼虫、疣足幼虫和刚节幼虫而达稚虫。幼虫和幼体的体节(X_1)与体长(Y_1)的回归方程为Y_1=139.77X_1-24.62;幼虫的生长特性为Y_2=323.40X_2~(0.35);幼虫和幼体的实验表明,亚心形扁藻是较好的饵料;疣足幼虫对海水的适宜比重为1.010～1.025;幼虫的生长速度随着投饵密度的增加而加快;在幼虫培养期间应铺以泥沙底质为佳。     

Neighborhood-scale urban form,travel behavior,and CO2 emissions in Beijing: implications for low-carbon urban planning

With an increasing awareness of global climate change, the effect of urban spatial organization, at both city and neighborhood scales, on urban CO₂ emission reduction has attracted much scholarly and practical attention. Using Beijing as a case study, this article examines the extent to which neighborhood-scale urban form may contribute to reduction of travel-related CO₂ emissions in the context of rapid urbanization and spatial transformation. We derive complete travel-activity records of 1,048 residents from an activity diary survey conducted in 2007. Analysis using structural equation models finds that residents living in a neighborhood with higher land use mix, public transit accessibility, and more pedestrian-friendly street design tend to travel in a “low-carbon” manner and emit less CO₂ in daily travel, even controlling for residential and travel preferences. This article offers empirical evidence that sheds light on debates about policy measures to facilitate China’s transition toward sustainable and low-carbon urban development.