Arsenic in atmospheric deposition at the Czech-Polish border: two sampling campaigns 20 years apart

Arsenic (As) occurs in atmospheric deposition both in soluble and insoluble forms, mainly bound to fine aerosol particles (less than 2.5 microm). Interception deposition (i.e. fog, dew and ice accretion) represents a specific type of atmospheric deposition, which has been much more contaminated with As than bulk deposition. This study compares the As amount and its binding forms in bulk and interception deposition in the winters of 1984-1986 and 2003-2005 in the Orlické hory mountains (Adlergebirge) near the Czech-Polish border; sampled and analysed by the same methodology. The As concentrations in ice accretions decreased 16 times over the twenty year period (from 50 microg L(-1) to 3 microg L(-1)), while the pH values increased by 0.8 units. As concentrations in snow decreased from 15 microg L(-1) in 1984-1986 to <2 microg L(-1) in 2003-2005. This decline mirrored the considerable decrease in industrial emissions in Central Europe. Higher acidity of interception deposition (about 1 pH unit) in comparison with the bulk deposition was observed in both sampling periods. The quantity of bulk deposition (snowfall) also influenced the As concentration in interception deposition. Dry periods resulted in higher As-amounts in interception deposition due to limited washing of atmospheric aerosol particles by wet deposition. The As concentration and stability in atmospheric deposition are important for the study of subsequent As-migration and/or accumulation in soil -- groundwater -- surface water.     

Radiosensitization of Human Leukemic HL-60 Cells by ATR Kinase Inhibitor (VE-821): Phosphoproteomic Analysis

DNA damaging agents such as ionizing radiation or chemotherapy are frequently used in oncology. DNA damage response (DDR)—triggered by radiation-induced double strand breaks—is orchestrated mainly by three Phosphatidylinositol 3-kinase-related kinases (PIKKs): Ataxia teleangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK) and ATM and Rad3-related kinase (ATR). Their activation promotes cell-cycle arrest and facilitates DNA damage repair, resulting in radioresistance. Recently developed specific ATR inhibitor, VE-821 (3-amino-6-(4-(methylsulfonyl)phenyl)-N-phenylpyrazine-2-carboxamide), has been reported to have a significant radio- and chemo-sensitizing effect delimited to cancer cells (largely p53-deficient) without affecting normal cells. In this study, we employed SILAC-based quantitative phosphoproteomics to describe the mechanism of the radiosensitizing effect of VE-821 in human promyelocytic leukemic cells HL-60 (p53-negative). Hydrophilic interaction liquid chromatography (HILIC)-prefractionation with TiO₂-enrichment and nano-liquid chromatography—tandem mass spectrometry (LC-MS/MS) analysis revealed 9834 phosphorylation sites. Proteins with differentially up-/down-regulated phosphorylation were mostly localized in the nucleus and were involved in cellular processes such as DDR, all phases of the cell cycle, and cell division. Moreover, sequence motif analysis revealed significant changes in the activities of kinases involved in these processes. Taken together, our data indicates that ATR kinase has multiple roles in response to DNA damage throughout the cell cycle and that its inhibitor VE-821 is a potent radiosensitizing agent for p53-negative HL-60 cells.     

Neodymium triflate modified nafion composite membrane for reduced alcohol permeability in direct alcohol fuel cell

This paper reports an experimental study on the modification of nafion membrane with neodymium triflate, Nd(SO₃CF₃)₃, a rare earth triflate. The triflate ion resembles nafion in structure and has high lewis acidity, high coordination number, hygroscopic nature and thermal stability. These properties make the neodymium triflate (NdTfO) suitable to improve the performance of NdTfO/nafion membranes in direct alcohol fuel cell by reducing fuel permeability without compromising other properties. The NdTfO/nafion membranes reduced alcohol permeability by nearly 48%. The proton conductivity of 1% NdTfO/nafion was increased by at least 24% as compared to pure cast nafion membrane. The mechanical strength of 1% NdTfO/nafion was higher than that of pure cast nafion. The composite membrane was thermally and chemically stable and has potential for use in direct alcohol fuel cells. A DMFC was developed and its performance was evaluated using the composite membrane, which showed encouraging results.     

Surface Tension of Binary Mixtures Including Polar Components Modeled by the Density Gradient Theory Combined with the PC-SAFT Equation of State

In this study, the Cahn–Hilliard density gradient theory (GT) is used for predicting the surface tension of various binary mixtures at relatively wide temperature ranges and for testing the application of the GT for predictions of homogeneous nucleation. The GT was combined with two physically based equations of state (EoS), namely the perturbed-chain (PC) statistical associating fluid theory (SAFT) and its modification for polar substances the perturbed-chain polar (PCP) SAFT. The GT applied to the planar phase interface was employed to predict the interfacial tension for various quadrupolar (CO₂ and benzene) and dipolar (difluoromethane, i.e., R32; pentafluoroethane, i.e., R125; and 1,1,1,2-tetrafluoroethane, i.e., R134a) substances and for five binary mixtures including polar components (n-decane + CO₂, benzene + CO₂, R32 + R125, R32 + R134a, R134a + R125). The PCP-SAFT EoS combined with the GT provides more accurate results for both the quadrupolar and dipolar substances than the original PC-SAFT EoS. Besides the planar phase interface, the GT was also applied to the spherical phase interface simulating a critical cluster occurring in homogeneous nucleation of droplets. Carbon dioxide was considered, because it has a relatively high quadrupole moment and because of its relevance to natural gas processing. Application of the PCP-SAFT EoS provides a significant improvement compared to the PC-SAFT EoS, and it is clearly superior to the classical cubic Peng–Robinson EoS, which is still used for modeling droplet nucleation.     

Rapid detection of genus Cronobacter in powdered infant formula milk

Rapid and specific detection of Cronobacter spp. in powdered infant formula milk (IFM) is of great importance for health and safety reasons. In the present study, two rapid and specific methods, the immunochromatographic strip (ICT) and the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), were tested for the detection of Cronobacter spp. in IFM. IFM samples spiked by Cronobacter spp. were correctly detected as positive by both methods. These results were verified by the classical cultivation microbiological method (ISO/TS 22964:2006). All three methods were used for the analyses of 13 IMF samples from a local market with identical results. Only one IFM sample was found to be positive. Both tested methods considerably reduced the total detection time, to 24?h (ICT) and 46?h (MALDI-TOF MS), whereas the reference ISO/TS 22964:2006 method needs 140?h.     

New applications of pHluorin—measuring intracellular pH of prototrophic yeasts and determining changes in the buffering capacity of strains with affected potassium homeostasis

pHluorin is a pH‐sensitive variant of green fluorescent protein for measuring intracellular pH (pH_in) in living cells. We constructed a new pHluorin plasmid with the dominant selection marker KanMX. This plasmid allows pH measurements in cells without auxotrophic mutations and/or grown in chemically indefinite media. We observed differing values of pH_in for three prototrophic wild‐types. The new construct was also used to determine the pH_in in strains differing in the activity of the plasma membrane Pma1 H⁺‐ATPase and the influence of glucose on pH_in. We describe in detail pHluorin measurements performed in a microplate reader, which require much less hands‐on time and much lower cell culture volumes compared to standard cuvettes measurements. We also utilized pHluorin in a new method of measuring the buffering capacity of yeast cell cytosol in vivo, shown to be ca. 52 mM /pH for wild‐type yeast and moderately decreased in mutants with affected potassium transport. Copyright © 2010 John Wiley & Sons, Ltd.     

Soybean (Glycine max) Is Able to Absorb,Metabolize and Accumulate Fenbendazole in All Organs Including Beans

Although manure is an important source of minerals and organic compounds it represents a certain risk of spreading the veterinary drugs in the farmland and their permeation to human food. We tested the uptake of the anthelmintic drug fenbendazole (FBZ) by soybean, a common crop plant, from the soil and its biotransformation and accumulation in different soybean organs, including beans. Soybeans were cultivated in vitro or grown in a greenhouse in pots. FBZ was extensively metabolized in roots of in vitro seedlings, where sixteen metabolites were identified, and less in leaves, where only two metabolites were found. The soybeans in greenhouse absorbed FBZ by roots and translocated it to the leaves, pods, and beans. In roots, leaves, and pods two metabolites were identified. In beans, FBZ and one metabolite was found. FBZ exposure did not affect the plant fitness or yield, but reduced activities of some antioxidant enzymes and isoflavonoids content in the beans. In conclusion, manure or biosolids containing FBZ and its metabolites represent a significant risk of these pharmaceuticals entering food consumed by humans or animal feed. In addition, the presence of these drugs in plants can affect plant metabolism, including the production of isoflavonoids.