Natural organic matter (NOM) induces oxidative stress in freshwater amphipods Gammarus lacustris Sars and Gammarus tigrinus (Sexton)

Humic substances comprise the majority of natural organic matter (NOM) on Earth, including dissolved organic matter in freshwater systems. Recent studies show that these substances directly interact with aquatic organisms as chemical stressors. The aim of the present study was to investigate the mode of action of dissolved NOM on the freshwater amphipods Gammarus lacustris Sars and Gammarus tigrinus (Sexton), and in particular, to determine if NOM induces or promotes internal oxidative stress. NOM was isolated by reverse osmosis from a brown-water lake in Brandenburg State, Germany. Oxidative stress markers, such as lipid peroxidation, cell internal hydrogen peroxide concentration, as well as peroxidase, catalase and glutathione S-transferase activities, were quantified. Exposure of both amphipod species to NOM caused a significant increase in lipid peroxidation, hydrogen peroxide concentration, catalase, peroxidase and glutathione S-transferase activities. Both species showed a two-stage antioxidant response: the first stage allowed the organisms to effectively eliminate ROS and to protect cells from damage, whereas the second stage leads to H2O2 accumulation in combination with destruction of lipid structures in the cells and, finally, functional damage or even death of the organism.     

Creativity as flexible cognitive control.

Creative individuals have been described in terms suggestive of greater automatic processing (e.g., defocused attention, looser associations) and greater controlled processing (e.g., greater abilities to focus while working on a creative task). Both views cannot be correct from a static ability-related perspective. On the other hand, both views could be correct if creative individuals are better able to modulate the functioning of their cognitive control system in a context-sensitive manner. The present study (N = 50) assessed individual differences in creativity in terms of original responses on the Torrance Test of Creative Thinking (Torrance, 1974) and also in terms of creative behavior on the Creative Achievement Questionnaire (Carson, Peterson, & Higgins, 2005). The same participants performed a color–word Stroop task. Creative individuals were neither more nor less capable of overriding cognitive conflicts on incongruent (relative to congruent) Stroop trials. On the other hand, creative individuals displayed more flexible cognitive control, as defined by greater cognitive control modulation from trial to trial. Implications for theories of creativity and its underlying processing basis are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining the process by which marital adjustment affects maternal warmth: The role of coparenting support as a mediator.

This study assessed the longitudinal process by which marital adjustment affects change in maternal warmth over time. Change in coparenting support was examined as the potential mechanism by which the marriage affects parenting. Self-report data were gathered from 148 married mothers of first-born 4th graders at 3 time points, over the transition to early adolescence. Path analyses supported the proposed hypothesis, indicating that marital adjustment leads to increased coparenting support, which then leads to increased maternal warmth. Two alternative models of the time-ordered direction of effects among the study variables were ruled out. This study has important implications for the development of parenting interventions targeting the promotion of maternal warmth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxidation of Fine Tantalum Particles: Metastable Intermediates and Multistep Kinetics

Oxidation of Metals - The metastable tantalum suboxides have been found to be a cause of complicated oxidation behaviour of fine tantalum particles when heated in air at moderate temperatures. Fine...     

Controlled copolymerization of acrylonitrile with methyl acrylate and dimethyl itaconate via ARGET ATRP mechanism

The peculiarities of controlled copolymerization of acrylonitrile with methyl acrylate and dimethyl itaconate in the presence of copper-based catalytic system were investigated. It was shown that the polymerization proceeds in a controlled mode in accordance with ARGET ATRP mechanism. The increase of molecular weights in a strict agreement with theoretically predicted values is observed. The formation of copolymers was confirmed by NMR and MALDI TOF MS analysis. The introduction of mentioned monomers to acrylonitrile results in slight decrease of the polymerization rate. The performed calorimetric investigations showed the smoothing of exothermic effect of the oxidative stabilization of formed copolymers.     

Heterostructures based on Pd–Au nanoparticles and cobalt phthalocyanine for hydrogen chemiresistive sensors

In this work, the effect of Pd, Au and PdAu nanoparticles on sensor response of cobalt phthalocyanine films to hydrogen was studied. For this purpose, novel heterostructures based on cobalt phthalocyanine and PdAu nanoalloys were obtained by a combination of vacuum thermal evaporation and pulsed metalorganic chemical vapor deposition (MOCVD) and investigated as active layers for hydrogen detection. The structural features and phase composition of the prepared heterostructures were studied by the techniques of X-ray diffraction, transmission electron microscopy and electron diffraction. The concentration of metal nanoparticles in the samples was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The chemiresistive sensor response of CoPc/M (M = Pd, Au, Pd_0.2Au_0.8 and Pd_0.8Au_0.2) to hydrogen (100–400 ppm, room temperature) was compared with that of bare CoPc films. It was shown that the sensor response of the investigated heterostructures to hydrogen (300 ppm) increased in the order CoPc (0.2%) < CoPc/Pd_0.2Au_0.8 (1.9%) ~ CoPc/Au (2.2%) < CoPc/Pd (2.7%) < CoPc/Pd_0.8Au_0.2 (5.6%).     

Improvement of enzyme electrocatalysis using substrate containing electroactive polymers. Towards limiting efficiencies of bioelectrocatalysis

Direct electrocatalysis by the enzymes in the absence of any freely diffusing mediators requires proper orientation of the protein macromolecule on the electrode surface. We report a conception on how to improve efficiency of bioelectrocatalysis using electroactive polymers containing analogues of the enzyme substrates (usually acting as artificial donors-acceptors). Indeed, substrate analogues having affinity to terminal redox groups of the enzymes can anchor them in an optimal orientation upon immobilization. The improvement of bioelectrocatalysis using such electroactive polymers is reported for different enzymes: hydrogenases and cellobiose dehydrogenase. Highly efficient electrocatalysis by hydrogenases was determined by thermodynamics of the catalyzed reaction confirming the direct bioelectrocatalysis. For hydrogenases immobilized over viologen substituted conducting polymers the limiting performance characteristics in bioelectrocatalysis have been achieved.     

2′‐Bispyrene‐Modified 2′‐O‐Methyl RNA Probes as Useful Tools for the Detection of RNA: Synthesis,Fluorescent Properties,and Duplex Stability

The synthesis and properties two series of new 2′‐O‐methyl RNA probes, each containing a single insertion of a 2′‐bispyrenylmethylphosphorodiamidate derivative of a nucleotide (U, C, A, and G), are described. As demonstrated by UV melting studies, the probes form stable complexes with model RNAs and DNAs. Significant increases (up to 21‐fold) in pyrene excimer fluorescence intensity were observed upon binding of most of the probes with complementary RNAs, but not with DNAs. The fluorescence spectra are independent of the nature of the modified nucleotides. The nucleotides on the 5′‐side of the modified nucleotide have no effect on the fluorescence spectra, whereas the natures of the two nucleotides on the 3′‐side are important: CC, CG, and UC dinucleotide units on the 3′‐side of the modified nucleotide provide the maximum increases in excimer fluorescence intensity. This study suggests that these 2′‐bispyrene‐labeled 2′‐O‐methyl RNA probes might be useful tools for detection of RNAs.