PC/硅氧烷复合材料的阻燃抑烟机理研究

聚碳酸酯(PC)作为性能优异的工程塑料被广泛用于高铁、飞机等特殊领域,但其燃烧时热释放及产烟量较大,故对其进行抑烟阻燃改性便尤为重要.通过将商用有机硅阻燃剂与抗滴落剂复配制备PC复合材料,证明在添加3 wt％ 的有机硅阻燃剂后即可使PC达到V0级,LOI上升至34.5％,热释放速率峰值下降58.86％,烟及CO2释放速...     

挠力河流域农垦开发中居民地景观生态特征的变化

运用G IS、景观格局分析与聚落分析方法定量分析了挠力河流域在快速农垦开发中居民地分布格局的时空变化,探讨了景观格局形成的机制。景观指数分析表明近50 a来居民地面积和数目激增,居民地斑块面积、聚集度增大,表明人类对挠力河流域景观扰动持续增强。在所有背景地类中,居民地与耕地的邻接比例最高。伴随居民地和耕地迅速扩张,两者邻接比例呈上升趋势,两者相互影响越来越大。不同时期居民地扩张强度高值区分布有所不同,主要分布在早期的耕地新增区,1954—2000年挠力河流域居民地扩张高值区最终主要分布于该流域的西部与中部。虽然居民地数目和面积均激增,各居民地之间的距离亦呈缩短趋势,但居民地最近邻点指数表明,近50 a来挠力河流域居民地分布类型一直为随机分布,农垦经济仍占主导地位,人为规划比城镇发达地区薄弱。     

The Lyon-Turin High-Speed Rail: The Public Debate and Perception of Environmental Risk in Susa Valley,Italy

When the construction of the Lyon-Turin segment of the new European high-speed rail network was first publicly announced at the beginning of the 1990s, it immediately found fierce opposition from the inhabitants of Susa Valley, Italy, one of the areas to be cut across by such infrastructure. At issue were the project’s potential environmental impact and its consequences on public health. This study intends to clarify environmental risk perception and public debate between the national government, local advocacy groups, and the inhabitants of Susa Valley. Two major phases of public reaction were identified: (1) an initial rebellious period of no real dialog among the project’s major stakeholders (exemplified by the popular “No TAV” [No High Speed Train] movement), followed by (2) a yielding period of intense multilateral negotiations centered on the activities of the “Lyon-Turin Environmental Observatory.” The results of a qualitative cross analysis of the residents’ perception of the proposed high-speed rail revealed that public acceptance of risk in Susa Valley was influenced by the characteristics of hazards perceived by the residents and by the communicative approach used by the project’s various stakeholders. It also emerged that early dialog among all the parties involved was critical in forming a personal viewpoint on risk, which, once consolidated, defied new information and perspectives. Likely, a greater and earlier care taken by the other stakeholders to inform and consult the local population about the railway would have greatly eased the public debate.     

岷江干旱河谷甜樱桃发展优势及栽培技术研究

岷江上游干旱河谷特有的生态环境条件适宜发展优质特色水果.甜樱桃作为该区域新兴特色水果之一,近5年来发展面积已超过了400hm2.甜樱桃的引种和规模化栽培表明,岷江上游干旱河谷区发展优质、高产甜樱桃具有独特的优势.总结了岷江干旱河谷栽培甜樱桃的成熟技术和管理措施,探讨了发展甜樱桃的巨大潜力,同时对存在的问题进行了分析,以期为汶川地震灾害农业产业的恢复重建和结构调整提出新的思路.     

Comparison of Two Parametric Methods to Estimate Pesticide Mass Loads in California’s Central Valley1

Saleh, Dina K., David L. Lorenz, and Joseph L. Domagalski, 2010. Comparison of Two Parametric Methods to Estimate Pesticide Mass Loads in California’s Central Valley. Journal of the American Water Resources Association (JAWRA) 00(0):1‐11. DOI: 10.1111/j.1752‐1688.2010.00506.x Abstract: Mass loadings were calculated for four pesticides in two watersheds with different land uses in the Central Valley, California, by using two parametric models: (1) the Seasonal Wave model (SeaWave), in which a pulse signal is used to describe the annual cycle of pesticide occurrence in a stream, and (2) the Sine Wave model, in which first‐order Fourier series sine and cosine terms are used to simulate seasonal mass loading patterns. The models were applied to data collected during water years 1997 through 2005. The pesticides modeled were carbaryl, diazinon, metolachlor, and molinate. Results from the two models show that the ability to capture seasonal variations in pesticide concentrations was affected by pesticide use patterns and the methods by which pesticides are transported to streams. Estimated seasonal loads compared well with results from previous studies for both models. Loads estimated by the two models did not differ significantly from each other, with the exceptions of carbaryl and molinate during the precipitation season, where loads were affected by application patterns and rainfall. However, in watersheds with variable and intermittent pesticide applications, the SeaWave model is more suitable for use on the basis of its robust capability of describing seasonal variation of pesticide concentrations.     

本地源尘污染成因的模式分析

对河门口片区污染源进行调查,采用经验证后表明适合攀枝花地区的山谷模式,对河门口片区的尘污染现状成因进行分析,研究了污染物种类、重点污染源类别、主要污染行业对片区内各控制点的影响,发现由于受山区地形影响,片区内各控制点污染状况受相邻污染源影响较大.     

Biological silicon nanoparticles improve Phaseolus vulgaris L. yield and minimize its contaminant contents on a heavy metals-contaminated saline soil

The synthesis of biological silicon nano-particles (Bio-Si-NPs) is an eco-friendly and low-cost method. There is no study focusing on the effect of Bio-Si-NPs on the plants grown on saline soil contaminated with heavy metals. In this study, an attempt was made to synthesis Bio-Si-NPs using potassium silica florid substrate, and the identified Aspergillus tubingensis AM11 isolate that separated from distribution systems of the potable water. A two-year field trial was conducted to compare the protective effects of Bio-Si-NPs (2.5 and 5.0 mmol/L) and potassium silicate (10 mmol/L) as a foliar spray on the antioxidant defense system, physio-biochemical components, and the contaminants contents of Phaseolus vulgaris L. grown on saline soil contaminated with heavy metals. Our findings showed that all treatments of Bio-Si-NPs and potassium silicate significantly improved plant growth and production, chlorophylls, carotenoids, transpiration rate, net photosynthetic rate, stomatal conductance, membrane stability index, relative water content, free proline, total soluble sugars, N, P, K, Ca²⁺, K⁺/Na⁺, and the activities of peroxidase, catalase, ascorbic peroxidase and superoxide oxide dismutase. Application of Bio-Si-NPs and potassium silicate significantly decreased electrolyte leakage, malondialdehyde, H₂O₂, O₂^??, Na⁺, Pb, Cd, and Ni in leaves and pods of Phaseolus vulgaris L. compared to control. Bio-Si-NPs were more effective compared to potassium silicate. Application of Bio-Si-NPs at the rate of 5 mmol/L was the recommended treatment to enhance the performance and reduce heavy metals content on plants grown on contaminated saline soils.     

How conservation and humanitarian groups respond to production of border security on the Arizona–Sonora border

US policies for securing the border with Mexico are driven by multiple political concerns, including the desire to control illegal trade and immigration in a way that conveys “border security” to a national audience. Highly visible border enforcement near urban centres and via the border fence has pushed migrants into far less visible and remote wilderness areas, driving both ecological degradation and a humanitarian crisis. This study employed ethnographic methods to explore how natural resource agency employees and humanitarian volunteers in Altar Valley Arizona perceived and responded to the production of border security. We found that both groups recognised human rights and environmental concerns, although they assigned different priorities and addressed them through conflicting means. As in other cases where consumers are separated from production practices, there was a general consensus among informants that it was important to raise the consciousness of the national audience about the negative externalities of producing border security.     

Views of Private-Land Stewardship among Latinos on the Texas–Tamaulipas Border

Successful conservation efforts require understanding predictors of private-land stewardship (PLS), its definitions, and what people feel they owe stewardship responsibility to. Various strands of research have touched on the concept, but there is little research focusing on how it is communicated and enacted among the lay public, especially among Latinos. We used a case study in the Lower Rio Grande Valley of Texas to address this gap by identifying and assessing Latino views of PLS. Our results indicate positive relationships between self-identification as a land steward, male gender, and agricultural-land ownership. Respondents associated PLS with property maintenance (60%), natural-resource conservation (14%), and addressing pollution problems (21%). They viewed PLS as a responsibility owed to family rather than to a larger community.     

A Study on Ionizing Emissions from Limestone Samples using CR-39 Solid State Nuclear Track Detector

Limestone is an item most commonly consumed by the people in the Barak Valley area of Assam along with betel leaves. Also limestone chips are extensively used for water treatment in filter beds of these areas. A preliminary investigation on the activity of the samples of limestone, collected from the local market at Silchar, Assam, indicated the presence of beta and gamma-ray activity, prompting further investigations for the presence of alpha particle emitting radionuclides. Also the study of the ionising emissions from these samples using solid state nuclear track detector (SSNTD) has revealed the presence of spontaneous fission fragments along with alpha particles. This paper presents an account of the results obtained from the SSNTD studies of these limestone samples.