一种硫离子响应杀菌材料的制备及应用研究

目的制备硫离子响应杀菌材料,研究它在不同浓度铜离子条件下的封装效果,以及在不同浓度硫离子条件下的释放行为。方法选择埃洛石纳米管为载体并用透射电镜进行表征、采用真空负载的方式,将甲硝唑和苯骈三氮唑(BTA)分步填充到埃洛石纳米管内部,使用紫外分光光度法测试不同浓度铜离子对纳米管中甲硝唑的封堵效果,以及材料在不同浓度硫离子条件下的释放情况。结果实验中通过调整铜离子浓度发现,铜离子浓度越大对甲硝唑的封堵效果越好,当铜离子浓度达到160 mmol/L时,对甲硝唑的封堵效果最好。杀菌材料在外界硫离子达到0.1mmol/L后,甲硝唑的释放浓度迅速提高,进一步提高硫离子浓度,释放情况改变不明显。结论铜离子浓度达到160 mmol/L时,材料的封装效果是最好的。材料能够对硫离子实现响应释放,且对应的临界浓度为0.1 mmol/L。     

The dynamics of artisanal and small-scale mining reform

Artisanal and small‐scale mining are activities that have long been established in many developing countries, employing millions of people globally, either directly or in affiliated industries. Also, such activities are deplored for their adverse environmental impacts and their general avoidance of governments, tax collectors and other regulators. Decades of work have gone into addressing these problems, but with limited overall progress in evidence. Going back to some of the key dynamic relationships involved in artisanal mining and small‐scale mining, the need for policy reform that gives consistent and effective incentives is argued to be the foundation on which other discussions about environmental protection, sustainability and livelihoods can be built.     

福建省林权改革环境影响农户调查研究——以三明市和永安市为例

福建是全国第一个开展林权制度改革的省份。本文通过在福建省三明市和永安市实地调研的基础上,探讨福建省森林资源经营的改变对环境的影响。研究发现,林区的绝大部分林农对林权改革持满意的态度,认为林权改革前后对环境的影响有变化。数据分析显示,林改后,对林业的投入对于森林旅游的影响成正比;家庭年均收入对空气质量的影响成负相关。研究建议,继续加大对林业的投入,科学编制森林经营规划和经营方案,促进生态环境改善和林农的增收。     

Toward sustainable livelihoods after war: Reconstituting rural land tenure systems

Land tenure plays a primary role in sustainable development efforts. However armed conflict and its repercussions reconfigure the network of social relations upon which all land tenure systems depend. In post‐conflict settings new laws have the opportunity to address tenure issues in the context of what people are already doing ‘on the ground’, with a view to moving from the fluidity of post‐conflict situations to a more solidified and peaceful social and legal environment. However there exists a lack of tools to analyze postwar land tenure and the prospects for reconstituting tenure systems to support recovery and development. This paper uses the Sustainable Livelihoods framework to examine postwar land tenure issues in order to draw out latent opportunities within emergent informal smallholder tenure constructs which may have utility in the reconstitution of national tenure systems.     

Understanding the Lessons and Limitations of Conservation and Development

Abstract: The lack of concrete instances in which conservation and development have been successfully merged has strengthened arguments for strict exclusionist conservation policies. Research has focused more on social cooperation and conflict of different management regimes and less on how these factors actually affect the natural environments they seek to conserve. Consequently, it is still unknown which strategies yield better conservation outcomes? We conducted a meta‐analysis of 116 published case studies on common resource management regimes from Africa, south and central America, and southern and Southeast Asia. Using ranked sociodemographic, political, and ecological data, we analyzed the effect of land tenure, population size, social heterogeneity, as well as internally devised resource‐management rules and regulations (institutions) on conservation outcome. Although land tenure, population size, and social heterogeneity did not significantly affect conservation outcome, institutions were positively associated with better conservation outcomes. There was also a significant interaction effect between population size and institutions, which implies complex relationships between population size and conservation outcome. Our results suggest that communities managing a common resource can play a significant role in conservation and that institutions lead to management regimes with lower environmental impacts.     

Delivering on the Promise of Agroforestry

Agroforestry – the traditional practice of growing trees on farms for the benefit of the farm family and for the environment – was brought from the realm of indigenous knowledge into the forefront of agricultural research less than two decades ago. It was promoted widely as a sustainability-enhancing practice that combines the best attributes of forestry and agriculture. Based on principles of natural resource management and process-oriented research, agroforestry is now recognized as an applied science, that is instrumental in assuring food security, reducing poverty and enhancing ecosystem resilience at the scale of thousands of smallholder farmers in the tropics.Trees on farms provide both products and services: they yield food, fuelwood, fodder, timber and medicines, which farm families can use at home or take to market to bring in much-needed cash; they replenish organic matter and nutrient levels in soils and they help control erosion and conserve water. The International Centre for Research in Agroforestry, and its partners, are working to integrate the functions of trees with policy and institutional improvements that aim at facilitating wide-scale adoption by farmers.Two examples described in this paper are replenishing soil fertility in sub-Saharan Africa using short-term improved tree and shrub fallows and the results of agroforestry research to support significant land tenure policy in southeast Asia.Although just one option in sustainable land-use, science-based agroforestry has the potential to produce economically, socially and environmentally sound results for the billions of people who depend on this ancient practice and modern science.     

The incidence of land tenure insecurity in Southern Africa: Policy implications for sustainable development

The study presented in this article used a combination of key informant interviews and a review and synthesis of existing country level literature to identify the major sources of land tenure insecurity in six Southern African countries: Botswana, Lesotho, Malawi, Mozambique, South Africa, and Zambia. Findings reveal that the main causes of land tenure insecurity experienced in Southern Africa include lack of land rights of minority groups, unclear or overlapping land rights, overcrowding, land alienation into leasehold, insecurity of farm workers and farm labour tenants, inappropriate and exploitative administrative practices, land encroachment and illegal settlers and limited women's land rights. The article presents a summary of land tenure security related initiatives that the study countries have or are in the process of adopting. Analysis of these initiatives shows that tenure reforms have focused on changing the law and rules but little has been done to translate new laws into implementable programs; capacity building; prioritization of resources to support tenure reform; provision of complementary policies and incentives; addressing HIV/AIDS‐land tenure related problems; and monitoring and evaluation. The paper contends that these policy issues should be addressed in order to ensure realization of land tenure security for all.     

福建省林权改革环境影响农户调查研究—以三明市和永安市为例

福建是全国第一个开展林权制度改革的省份。本文通过在福建省三明市和永安市实地调研的基础上,探讨福建省森林资源经营的改变对环境的影响。研究发现,林区的绝大部分林农对林权改革持满意的态度,认为林权改革前后对环境的影响有变化。数据分析显示,林改后,对林业的投入对于森林旅游的影响成正比;家庭年均收入对空气质量的影响成负相关。研究建议,继续加大对林业的投入,科学编制森林经营规划和经营方案,促进生态环境改善和林农的增收。     

Determinants of chorus tenure in barking treefrogs (Hyla gratiosa)

In all species of anuran amphibians studied to date, male mating success is positively correlated with male chorus tenure (the number of nights that a male is present in breeding aggregations), yet males spend only a small portion of the total breeding season in choruses. Three hypotheses might explain abbreviated chorus tenure in anuran amphibians: (1) mortality, (2) energy limitations, and (3) movement among choruses. I tested these hypotheses in a study of the barking treefrog (Hyla gratiosa), a species with very abbreviated chorus tenure. Mortality accounted for the short tenures of some males: an estimated 20% of males died while calling in the chorus. Energy limitations were an important determinant of chorus tenure. Males lost weight over successive nights in the chorus, and males with longer chorus tenures were in better condition on their first night in the chorus, lost condition more slowly, and were in poorer condition on their last night in the chorus than were males with shorter chorus tenures. Males that I fed crickets as they left the chorus returned sooner and for more nights than did control (unfed) males. Movement between ponds did not explain abbreviated chorus tenure: less than 16% of the males called at more than one pond, and these males increased their chorus tenures by a median of only 2.5 nights by calling in another chorus. Thus, abbreviated chorus tenure in H. gratiosa appears to be primarily the result of energy limitations, with mortality playing a secondary role.     

林地面积增加提高了农户营林积极性吗?——基于9省1 504个农户数据的倾向值匹配分析

论文利用9省1 504个农户调研数据,实证检验了新一轮集体林改后林地面积增加对农户营林积极性的因果效应。考虑到农户对林地经营面积决策的内生性问题,采用倾向值匹配方法对选择性偏差进行控制。匹配后,处理组和控制组在多个标准上均通过了平衡性检验。结果显示,林地面积增加确实促进了农户营林积极性的提高,但这是一个缓慢的动态调整过程。其中,资本投入强度在2010年以后才逐步表现为显著增加,增长率约为25%~27%,2013年进一步强化为28%~34%。资本投入强度的增加主要是由化肥和农药投入增加引起的,对种苗的投入强度并没有显著改善。这种差异说明,新一轮林改提高了农户的森林经营和管护积极性,但对造林行为的影响有限。同时农户并没有因为林地面积增加而显著提高劳动力的投入强度。这种资本对劳动的替代与农户的非农就业行为密切相关。