Abstract  In this work we investigate the limits of uptake of metallic silver by two common metallophytes, Brassica juncea (BJ) and Medicago sativa (MS) and assess the form and distribution of the metal once sequestered by the plants. BJ accumulated up to 12.4 wt.% silver when exposed to an aqueous substrate containing 1,000 ppm AgNO3 for 72 h, however silver uptake was largely independent of exposure time and substrate silver concentration. MS accumulated up to 13.6 wt.% silver when exposed to an aqueous substrate containing 10,000 ppm AgNO3 for 24 h. In contrast to BJ there was a general trend for MS showing an increase in metal uptake with a corresponding increase in the substrate metal concentration and exposure time. In both cases the silver was stored as discrete nanoparticles, with a mean size of ?50 nm. According to the hyperaccumulation definition of Brooks et al. (Brooks RR, Chambers MF, Nicks LJ, Robinson BH (1998) Phytomining. Trends Plant Sci 3:359?362), this is the first report of the hyperaccumulation of silver in any plant species.

Abstract  Anthropogenic cycling of silver in 1997 is presented using three discrete governmental units: 64 countries encompassing what we believe to be over 90% of global silver flows, 9 world regions, and the entire planet. Using material flow analysis (MFA) techniques, the country level cycles are aggregated to produce the regional cycles, which are used to form a "best estimate" global cycle. Interesting findings include the following: (1) several silvermining countries export ore and concentrate but also import silver-containing semiproducts and products; (2) the level of development for a country, as indicated by the gross domestic product, is a fair indicator of silver use, but several significant outliers exist; (3) the countries with the greatest mine production include Mexico, the United States, Peru, and China, whereas the United States, Japan, India, Germany, and Italy lead in the fabrication and manufacture of products; (4) North America and Europe's use of silver products exceed that of other regions on a per capita basis; (5) global silver discards, including tailings and separation waste, totaled approximately 57% of the silver mined; (6) approximately 57% of the silver entering waste management globally is recycled; and (7) the amount of silver entering landfills globally is comparable to the amount found in tailings. The results of this MFA lay the basis for further analysis, which in turn can offer insight into natural resource policy,the characterization of environmental impact, and better resource management.

Abstract  We disclose novel classes of alloy nanocompositions that have superior decontaminant properties which are derived from their superior immediate and residual biocidal properties. By decontaminant properties it is understood that the preferred compositions are antiseptics, disinfectants, sanitizers, and/or sterilizers. By biocidal properties it is understood that the preferred compositions are excellent antimicrobials, antivirals, antifungals, and sporicidals. The preferred compositions have superior immediate and residual biocidal properties in free or bound form and they are safe to humans and environmental friendly. The nanocomposites described herein are in two element, three element or four element combinations. The preferred compositions have additional properties such as they are magnetic and/or they have distinct natural colors. The compositions are produced in different sizes ranging from 5 nm up to 500 nm, and for some other classes above 500 nm.

Abstract  Conventional and novel syntheses of silver nanoparticles are considered, their advantages and shortcomings are analysed. Attention is focused on the shape-controlled methods of preparation of nanosized particles. The unique optical and antibacterial properties of nanosilver and related applications are discussed.