Adsorption of phenanthrene on natural snow

The snowpack is a reservoir for semivolatile organic compounds (SVOCs) and, in particular, for persistent organic pollutants (POPs), which are sequestered in winter and released to the atmosphere or hydrosphere in the spring. Modeling these processes usually assumes that SVOCs are incorporated into the snowpack by adsorption to snow surfaces, but this has never been proven because the specific surface area (SSA) of snow has never been measured together with snow composition. Here we expose natural snow to phenanthrene vapors (one of the more volatile POPs) and measure for the first time both the SSA and the chemical composition of the snow. The results are consistent with an adsorption equilibrium. The measured Henry's law constant is H(Phen)(T) = 2.88 x 10(22) exp(-10660/7) Pa m2 mol(-1), with Tin Kelvin. The adsorption enthalpy is delta H(ads) = -89 +/- 18 kJ mol(-1). We also perform molecular dynamics calculations of phenanthrene adsorption to ice and obtain AHads = -85 +/- 8 kJ mol(-1), close to the experimental value. Results are applied to the adsorption of phenanthrene to the Arctic and subarctic snowpacks. The subarctic snowpack, with a low snow area index (SAI = 1000), is a negligible reservoir of phenanthrene, butthe colder Arctic snowpack, with SAI = 2500, sequesters most of the phenanthrene present in the (snow + boundary layer) system.     

SYBR<Superscript>®</Superscript>Green qPCR methods for detection of endogenous reference genes in commodity crops: a step ahead in combinatory screening of genetically modified crops in food and feed products

Identification of crops present in food and/or feed matrices represents an important step in the screening strategies targeting genetically modified organisms (GMO). Soybean, maize, oilseed rape, rice, cotton, sugar beet and potato are to date the most important sources of genetically modified materials imported in the European Union (EU). In order to allow detection of their presence in an integrated screening approach, a set of SYBR^®Green real-time polymerase chain reaction (qPCR) methods has been developed which can be used under the same assay conditions and at similar efficiency for each of the abovementioned crops. Each qPCR method is shown to meet the performance criteria (i.e. specificity, limit of detection and PCR efficiency) set by the European Network of GMO Laboratories (ENGL). When combined with the equivalent qPCR methods targeting GMO elements, these crop-specific SYBR^®Green qPCR methods can aid the development of an efficient tool for determining GMO presence in food and/or feed products.     

Efficient DG‐like formulation equipped with curved boundary edges for solving elasto‐acoustic scattering problems

A Discontinuous Galerkin (DG)‐based approach is proposed for computing the scattered field from an elastic bounded object immersed in an infinite homogeneous fluid medium. The proposed method possesses two distinctive features. First, it employs higher‐order polynomial‐shape functions needed to address the high‐frequency propagation regime. Second, it is equipped with curved boundary edges to provide an accurate representation of the fluid–structure interface. The most salient benefits resulting from the latter feature, as demonstrated by the numerical investigation, are the following: (i) an improvement by—at least—two orders of magnitude on the relative error and (ii) the disappearance of spurious resonance frequencies in the surrounding fluid medium. In addition, the reported numerical results reveal that when using cubic polynomials with less than three elements per wavelength, the proposed DG method computes the scattered field with a relative error below 1% for an elastic scatterer of about 30 wavelengths. This observation highlights the potential of the proposed solution methodology for efficiently solving mid‐frequency to high‐frequency elasto‐acoustic scattering problems. Copyright © 2014 John Wiley & Sons, Ltd.     

Removal of pesticide mixtures in a stormwater wetland collecting runoff from a vineyard catchment

Wetlands can collect contaminated runoff from agricultural catchments and retain dissolved and particle-laden pesticides. However, knowledge about the capacity and functioning of wetland systems with respect to the removal of pesticides is very limited. Here we show that stormwater wetlands can efficiently remove pesticides in runoff from vineyard catchments during the period of pesticide application, although flow and hydrochemical conditions of the wetland largely vary over time. During the entire agricultural season, the inflowing load of nine fungicides, six herbicides, one insecticide and four degradation products was 8.039 g whereas the outflowing load was 2.181 g. Removal rates of dissolved loads by the wetland ranged from 39% (simazine) to 100% (cymoxanil, gluphosinate, kresoxim methyl and terbuthylazine). Dimethomorph, diuron, glyphosate, metalaxyl and tetraconazole were more efficiently removed in spring than in summer. More than 88% of the input mass of suspended solids was retained, underscoring the capability of the wetland to trap pesticide-laden particles via sedimentation. Only the insecticide flufenoxuron was frequently detected in the wetland sediments. Our results demonstrate that stormwater wetlands can efficiently remove pesticide mixtures in agricultural runoff during critical periods of pesticide application, although fluctuations in the runoff regime and hydrochemical characteristics can affect the removal rates of individual pesticides.     

Kidney-Specific CAP1/Prss8-Deficient Mice Maintain ENaC-Mediated Sodium Balance through an Aldosterone Independent Pathway

The serine protease prostasin (CAP1/Prss8, channel-activating protease-1) is a confirmed in vitro and in vivo activator of the epithelial sodium channel ENaC. To test whether proteolytic activity or CAP1/Prss8 abundance itself are required for ENaC activation in the kidney, we studied animals either hetero- or homozygous mutant at serine 238 (S238A; Prss8^cat/+ and Prss8^cat/cat), and renal tubule-specific CAP1/Prss8 knockout (Prss8^PaxLC1) mice. When exposed to varying Na⁺-containing diets, no changes in Na⁺ and K⁺ handling and only minor changes in the expression of Na⁺ and K⁺ transporting protein were found in both models. Similarly, the α- or γENaC subunit cleavage pattern did not differ from control mice. On standard and low Na⁺ diet, Prss8^cat/+ and Prss8^cat/cat mice exhibited standard plasma aldosterone levels and unchanged amiloride-sensitive rectal potential difference indicating adapted ENaC activity. Upon Na⁺ deprivation, mice lacking the renal CAP1/Prss8 expression (Prss8^PaxLC1) exhibit significantly decreased plasma aldosterone and lower K⁺ levels but compensate by showing significantly higher plasma renin activity. Our data clearly demonstrated that the catalytic activity of CAP1/Prss8 is dispensable for proteolytic ENaC activation. CAP1/Prss8-deficiency uncoupled ENaC activation from its aldosterone dependence, but Na⁺ homeostasis is maintained through alternative pathways.     

Do individual constraints induce flexibility of visual field dependence following a virtual immersion? Effects of perceptive style and cybersickness

Virtual Reality - Accurately perceiving the gravitational direction is key to successful interaction in our terrestrial environment. In this context field dependence (FD), the importance given to...     

Fatigue delamination,initiation, and growth,under mode I and II of fracture in a carbon‐fiber epoxy composite

In this article, interlaminar crack initiation and propagation under mode I and II dynamic loading of an epoxy matrix reinforced with unidirectional carbon fibers were evaluated. Delamination in mode I was carried out employing the DCB test (Double Cantilever Beam). In mode II, the ENF test (End Notched Flexure) was used. The fracture toughness in mode I was obtained using the methods of the ASTM D5528 Standard, whereas in mode II, the methods were applied in accordance with the ESIS (European Structural Integrity Society) Protocol. Employing this experimental program, the fatigue curves (ΔG,N) and growth rate curves (ΔG, da/dN) in both fracture modes were determined for an asymmetry ratio R = 0.2. The influence of the manufacturing process of the material on its behavior with respect to crack growth onset may be deduced from the experimental results, mainly the presence of resin bags. Moreover, as the crack growth rate decreases for large crack lengths, crack growth may even cease if the critical fracture energy does not increase above the values obtained in the static characterization of the material. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Crowdsourcing innovation challenges: How participants react when their ideas are rejected

Although crowdsourcing challenges as tools for generating high levels of innovation have received much attention, little research has investigated the impact on participants when their submissions are rejected. This research is aimed at gaining a better understanding of the consequences of rejection for participants' relationships with the brand engaged in the crowdsourcing activity. To investigate these issues, two quantitative studies were carried out with participants whose challenge proposals had not been selected. The results highlight positive effects on participant–brand relationships, especially on brand attachment, proselytism, brand commitment and brand loyalty. A confirmatory, interview-based qualitative study then identifies managerial perspectives and marketing strategies for brands and crowdsourcing platforms following the announcement of challenge results. This paper contributes to both the co-creation and crowdsourcing literature by extending academic knowledge and provides opportunities for further research.