Nanosilver in consumer products and human health: more information required!

Commenting on "120 Years of Nanosilver History: Implications for Policy Makers" (Environ. Sci. Technol.2011, 45, 1177-1183). The title of the article seduces readers to the impression that we can look back at more than a century of safe use of nanosilver. In this context, colloidal silver and nanosilver have been sometimes used as synonyms. Historically, the term "colloidal silver" refers to dispersed silver particles encompassing a size range of 10-1000 nm. Following scientific definitions, "colloid" stands for freely dispersed particles in a fluid (heterogenic) phase irrespective of its size distribution, while the term "nanosilver" is used for categorization by size. Of course, just the labeling as such neither necessarily implies new hazard properties nor any specific risks; however, uncertainties and data gaps at many levels call for careful consideration and usually should take effect as alert signal for regulatory toxicologists all over the world. Within the frame of this short commentary, we would like to focus on some unclarified issues related to consumer products.     

Nachweis von Diethylenglycol in Wein Detection of Diethylenglycol in Wine

European Food Research and Technology - Der Nachweis von Diethylenglycol durch Dünnschichtchromatograpllie nach Anreicherung mittels Extrelut-Fertigsäule wird beschrieben. Die...     

Decision‐making in a model‐based design process

Decisions early in the design process have a big impact on the life cycle performance of a building. The outcome of a construction project can be improved if different design options can rapidly be analysed to assist the client and design team in making informed decisions in the design process. A model‐based design approach can facilitate the decision‐making process if the design alternatives' performances can be evaluated and compared. A decision‐making framework using a performance‐based design process in the early design phase is proposed. It is developed to support decision‐makers to take informed decisions regarding the life cycle performance of a building. A scenario is developed in order to demonstrate the proposed framework of evaluating the different design alternatives' energy performance. The framework is applicable to decision‐making in a structured design process, where design alternatives consisting of both objective and subjective evaluation criteria can be evaluated.     

Oxidation/reduction Reactions of molybdate ions in sodium sulfate at 1200 K

Cyclic voltammetric studies have been used to elucidate the electrochemical and coupled chemical reactions of solute molybdate ions on sodium sulfate at 1200 K in different melt basicities fixed by SO₂-O₂ atmospheres. The reaction mechanism was determined by use of the Nicholson and Shain diagnostic criteria in combination with the phase stability diagram. Within the regime of sodium sulfate stability, three reduction reactions occur. In a highly acidic melt, the reduction of molybdate ions (Mo in + 6 oxidation state) to Mo as + 4 is coupled to an irreversible chemical reaction whereby molybdenum dioxide precipitates. Molybdenum in oxidation state + 4 is reduced to Mo-(+2)-species which are immediately reoxidized to Mo-(+4)-species by an oxidizing agent in the melt, a so-called catalytic reaction. The reduction of Mo-(+2)-species to molybdenum follows in a very narrow potential range close to the previous reaction and has the same catalytic reaction mechanism. The reduction reactions are reversible. The reverse oxidation of molybdenum to the molybdate ion proceeds in three electron transfer steps.     

Occurrence and fate of emerging wastewater contaminants in Western Balkan Region

This paper reports on a comprehensive reconnaissance of over seventy individual wastewater contaminants in the region of Western Balkan (WB; Bosnia and Herzegovina, Croatia and Serbia), including some prominent classes of emerging contaminants such as pharmaceuticals and personal care products, surfactants and their degradation products, plasticizers, pesticides, insect repellents, and flame retardants. All determinations were carried out using a multiresidue analytical approach, based on the application of gas chromatographic and liquid chromatographic techniques coupled to mass spectrometric detection. The results confirmed a widespread occurrence of the emerging contaminants in municipal wastewaters of the region. The most prominent contaminant classes, determined in municipal wastewaters, were those derived from aromatic surfactants, including linear alkylbenzene sulphonates (LAS) and alkylphenol polyethoxylates (APEO), with the concentrations in raw wastewater reaching into the mg/l range. All other contaminants were present in much lower concentrations, rarely exceeding few microg/l. The most abundant individual compounds belonged to several classes of pharmaceuticals (antimicrobials, analgesics and antiinflammatories, beta-blockers and lipid regulators) and personal care products (fragrances). Due to the rather poor wastewater management practices in WB countries, with less than 5% of all wastewaters being biologically treated, most of the contaminants present in wastewaters reach ambient waters and may represent a significant environmental concern.     

Microstructural evolution of a Ni-based superalloy (617B) at 700 °C studied by electron microscopy and atom probe tomography

We report on the microstructural evolution of a polycrystalline Ni-based superalloy (Alloy 617B) for power plant applications at a service temperature of 700 °C. The formation of secondary M₂₃C₆-carbides close to grain boundaries (GBs) and around primary Ti(C,N) particles is observed upon annealing at 700 °C, where γ′ is found to nucleate heterogeneously at M₂₃C₆ carbides. Using atom probe tomography, elemental partitioning to the phases and composition profiles across phase and grain boundaries are determined. Enrichments of B at γ/M₂₃C₆ and γ′/M₂₃C₆ interfaces as well as at grain boundaries are detected, while no B enrichment is found at γ/γ′ interfaces. It is suggested that segregation of B in conjunction with γ′ formation stabilizes a network of secondary M₂₃C₆ precipitates near GBs and thus increases the creep rupture life of Alloy 617B. Calculations of the equilibrium phase compositions by Thermo-Calc confirm the chemical compositions measured by atom probe tomography.