量子点在食品安全检测中的应用研究

近年来,量子点由于其优异的荧光性能,被广泛地作为生物纳米探针用于食品安全分析领域。为了解量子点及其在食品安全检测中的应用研究现状,综述了量子点的组成结构、光学特性、制备方法,以及量子点在食品安全检测方面应用取得的最新进展,并对其研究方向进行展望,以期促进量子点在食品安全检测中得到进一步的推广和运用。     

Air pollution,food production and food security: A review from the perspective of food system

Air pollution negatively impacts food security. This paper reviews the current literature on the relationship between air pollution and food security from the perspective of food system. It highlights that agricultural emissions which substantially contribute to air pollution could happen at every stage along the food supply chain. Meanwhile, air pollution can not only affect plant growth and animal health but also shift market equilibrium of both agro-inputs and outputs in the food supply chain and thereby affect food security indirectly. Furthermore, this study evaluates the effects of agricultural policy and energy policy on food security and air pollution, respectively, and provides an overview of potential policy instruments to reduce air pollution while ensuring food security. Finally, we identify the remaining research and policy issues for further studies, mainly focusing on the study of household's bounded rational behaviors and the issue of rural aging population.     

Quantum dots for live cells, in vivo imaging, and diagnostics

Research on fluorescent semiconductor nanocrystals (also known as quantum dots or qdots) has evolved over the past two decades from electronic materials science to biological applications. We review current approaches to the synthesis, solubilization, and functionalization of qdots and their applications to cell and animal biology. Recent examples of their experimental use include the observation of diffusion of individual glycine receptors in living neurons and the identification of lymph nodes in live animals by near-infrared emission during surgery. The new generations of qdots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.     

Excitation spectra of circular, few-electron quantum dots

Studies of the ground and excited states in semiconductor quantum dots containing 1 to 12 electrons showed that the quantum numbers of the states in the excitation spectra can be identified and compared with exact calculations. A magnetic field induces transitions between the ground and excited states. These transitions were analyzed in terms of crossings between single-particle states, singlet-triplet transitions, spin polarization, and Hund's rule. These impurity-free quantum dots allow "atomic physics" experiments to be performed in magnetic field regimes not accessible for atoms.     

Food sovereignty, urban food access, and food activism: contemplating the connections through examples from Chicago

The idea of food sovereignty has its roots primarily in the response of small producers in developing countries to decreasing levels of control over land, production practices, and food access. While the concerns of urban Chicagoans struggling with low food access may seem far from these issues, the authors believe that the ideas associated with food sovereignty will lead to the construction of solutions to what is often called the ??food desert?? issue that serve and empower communities in ways that less democratic solutions do not. In Chicago and elsewhere, residents and activists often see and experience racial and economic inequalities through the variety of stores and other food access sites available in their community. The connections between food access, respect, and activism are first considered through a set of statements of Chicagoans living in food access poor areas. We will then discuss these connections through the work and philosophy of activists in Chicago centered in food sovereignty and food justice. Particular focus will be placed on Growing Power, an urban food production, distribution, and learning organization working primarily in Milwaukee and Chicago, and Healthy South Chicago, a community coalition focused on health issues in a working class area of the city.     

Advancing the human right to food in Canada: Social policy and the politics of hunger, welfare, and food security

This article argues that hunger in Canada, while being an outcome of unemployment, low incomes, and inadequate welfare, springs also from the failure to recognize and implement the human right to food. Food security has, however, largely been ignored by progressive social policy analysis. Barriers standing in the way of achieving food security include the increasing commodification of welfare and the corporatization of food, the depoliticization of hunger by governments and the voluntary sector, and, most particularly, the neglect by the federal and provincial governments of their obligations to guarantee the domestic right to food as expressed in international human rights law. The interconnectedness of hunger, welfare, and food security issues in a first world society are explored from the perspective of progressive social policy and food security analysis and the development of alternative strategies. In terms of advancing the human right to food in Canada, particular emphasis is placed on the role of the state and civil society, and the social and economic rights of citizenship built on an inclusive social policy analysis and politics of welfare, food security and human rights.     

Fiber, food, fuel, and fungal symbionts

Virtually all plants of economic importance form mycorrhizae. These absorbing organs of higher plants result from a symbiotic union of beneficial soil fungi and feeder roots. In forestry, the manipulation of fungal symbionts ecologically adapted to the planting site can increase survival and growth of forest trees, particularly on adverse sites. Vesicular-arbuscular mycorrhizae, which occur not only on many trees but also on most cultivated crops, are undoubtedly more important to world food crops. Imperatives for mycorrhizal research in forestry and agriculture are (i) the development of mass inoculum of mycorrhizal fungi, (ii) the interdisciplinary coordination with soil management, plant breeding, cultivation practices, and pest control to ensure maximum survival and development of fungal symbionts in the soil, and (iii) the institution of nursery and field tests to determine the circumstances in which mycorrhizae benefit plant growth in forestry and agri-ecosystems.     

Biodiversity,cultural diversity,and food equity

Biodiversity and genetic resources have become the focal point of major national and international biological and political debates regarding control, ownership, access, and erosion of critical resources. While these issues are key to environmental sustainability and food security, biodiversity and genetic resources must be seen in the broader context of their inextricable relationship to cultural diversity and to humans' view of nature. Nature is assumed to be constituted socially through a wide variety of human processes described collectively as culture. Three significant cultural factors, technology, science, and capitalism, are largely responsible for the secularization and homogenization of food and agriculture and the remaking of nature. These processes and forces may simultaneously and unwittingly create the problems of declines in biodiversity, cultural diversity, and food equity. Indeed, it may well be that the only way to conserve cultural biodiversity in the field is to conserve cultural diversity among peoples. This reunification of biodiversity and cultural diversity and food and agriculture will require new paradigms and institutional mechanisms that allow us to show our care for each other through our reverence for nature.Notes 1. This paper is based, in part, on the Presidential Address of the 1993 annual meeting of the Agriculture, Food, and Human Values Society and on work to appear in a forthcoming bookBiodiversity/Cultural Diversity: The Plant Germplasm Controversy in Cultural Context by L. Busch, W. Lacy, J. Burkhardt, D. Hemken, J. Moraga, J. de Souza Silva, and T. Koponen. Lincoln, NE: University of Nebraska Press. The research has been supported, in part, by grants from the National Science Foundations' Ethics and Values Studies Program and the USDA Cooperative State Research Service.     

Synergies in alternative food network research: embodiment,diverse economies,and more-than-human food geographies

As ecologically and socially oriented food initiatives proliferate, the significance of these initiatives with respect to conventional food systems remains unclear. This paper addresses the transformative potential of alternative food networks (AFNs) by drawing on insights from recent research on food and embodiment, diverse food economies, and more-than-human food geographies. I identify several synergies between these literatures, including an emphasis on the pedagogic capacities of AFNs; the role of the researcher; and the analytical and political value of using assemblage and actor-network thinking to understand the far-reaching forces and power disparities confronting proponents of more ethical and sustainable food futures.     

Values, public policy, and community food security

Values and beliefs regarding communityfood security were investigated among participants in2–3 day participatory planning events related to thelocal food system in six rural counties from oneregion of upstate New York. The results of Qmethodology reveal three distinct viewpoints: a) theSocial Justice viewpoint, which is primarily concernedwith hunger and the potential harm caused by welfarereform; b) the Pragmatist viewpoint, which values thecontributions agriculture makes to local communitiesand is not concerned about environmental or socialexternalities of the dominant food system; and c) theVisionary viewpoint, which also values agriculture inthe community but is very concerned aboutenvironmental and social externalities. After theplanning events, the Pragmatist viewpoint experiencedan 88% increase in members and the other twoviewpoints became less salient. Various categories ofprofessionals (e.g., nutrition, social welfare,agriculture, environmental) tend to express theviewpoints associated with their professions and/orthe client groups they serve. Despite thesedifferences among participants, the planning events inall six counties resulted in a wide range of goals andobjectives centered on a theme of re-localizing avariety of food system activities. These results arediscussed in relation to the desirability ofdeveloping an explicit philosophy of food andagriculture and the ideal processes required to doso.     

老龄化、种植目的与稻农化学农药减量

化学农药减量是促进农业绿色发展和保障农产品质量安全的重要途径。为此,基于湖北省和江西省613户水稻种植户的微观调研数据,实证检验老龄化、种植目的对农户化学农药减量行为的影响,并论证种植目的在老龄化对化学农药减量行为影响上的调节作用。研究发现:老龄化显著阻碍了农户的化学农药减量,但以自给为主要种植目的的稻农更倾向于减少化学农药施用。进一步发现,种植目的能有效缓解老龄化对农户化学农药减量行为的负面影响。据此提出对老龄农户进行教育培训、引导培育年轻化新型农民群体、完善农产品市场监督体系、强化农民食品安全理念的对策建议。     

农用地膜自然老化与人工老化相关性的研究

[目的]研究分析人工加速光老化与自然气候暴露老化试验两者的相关性.[方法]以乌鲁木齐天山区南端农田自然老化试验田和人工加速光老化试验箱作为检测地膜老化试验手段,对A、B、C三种不同配方的农用地膜进行老化前后力学性能分析,并研究了辐照强度、温度、老化时间对农用地膜老化寿命的影响.[结果]自然老化和人工老化试验都表明B膜抗老化性相对其它2个膜样较好.[结论]人工老化与自然老化拉伸强度和断裂伸长率变化规律非常吻合.说明用340 nm荧光紫外灯辐照度控制在0.68 W/m2、黑板温度为60℃、冷凝温度为60℃、光照3 h、冷凝3 h试验条件下,可模拟出人工加速光老化试验的老化速率是自然气候环境下暴露试验的10倍.