4,888 research outputs found

    Bimetallic Cooperativity in Proton Reduction with an Amido‐Bridged Cobalt Catalyst

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    The bimetallic catalyst [CoII2(L1)(bpy)2]ClO4 (1), in which L1 is an [NN′2O2] fused ligand, efficiently reduced H+ to H2 in CH3CN in the presence of 100 equiv of HOAc with a turnover number of 18 and a Faradaic efficiency of 94 % after 3 h of bulk electrolysis at −1.6 V (vs. Ag/AgCl). This observation allowed the proposal that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co−Namido−Co environment offered by L1. Experimental results revealed that the parent [CoIICoII] complex undergoes two successive metal‐based 1 e− reductions to generate the catalytically active species [CoICoI], and DFT calculations suggested that addition of a proton to one CoI triggers a cooperative 1 e− transfer by each of these CoI centers. This 2 e− transfer is an alternative route to generate a more reactive [CoII(CoII−H−)] hydride, thus avoiding the CoIII−H− required in monometallic species. This [CoII(CoII−H−)] species then accepts another H+ to release H2

    Religiousness and Perceived God Perfectionism Among Elite Athletes

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    Little research has been conducted examining the link between athletes’ religious beliefs and practices and coping with the pressures related to elite competition. The purpose of the study was to investigate athletes’ global self-worth and perfectionistic concerns as key variables that link religiousness and perceived God perfectionism to dealing with performance failure and appraisals of upcoming competition. Self-report data was collected from a sample of 99 elite athletes (Mdn age = 22, 48% female, 89% believed in God) that were currently competing at a NCAA D1, professional or Olympic level. We used structural equation modeling to test direct and indirect pathways of two separate theoretical models and bootstrapping for determining the significance of indirect effects. Self-worth and perfectionistic concerns were important in understanding the link between religious variables and outcomes in both models. Specifically, high levels of athlete religiousness were related to high levels of self-worth, which in turn was related to low levels of shame when recalling a disappointing performance. In contrast, perceived God perfectionism discrepancy (i.e. gap in perceived standards from God and the athletes’ performance) was related to shame via a positive relation to perfectionistic concern. Religiousness was also directly related to feelings of comfort from God, whereas perceived God perfectionism was directly related to athletes’ anger towards God after experiencing disappointment. For the second model, religiousness was linked to high levels of challenge appraisals and low levels of stress and threat appraisals of competition through high levels of global self-worth. On the other hand, perceived God perfectionism discrepancy was related to all three appraisals of competition through high perfectionistic concern and low self-worth. Overall, our findings suggest that religiousness can serve as an important resource for athletes or contribute to psychological difficulties. Implications of our findings for practitioners are discussed

    A New Class of Photoresponsive Surfactants

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    Recently, surface tension has been shown to be important in emerging high technologies, such as in pumping and control of flow in microfluidic devices, in microchemical analysis of complex fluids, and in rapid DNA screening, etc. Advances in these new technologies will depend strongly on the availability of flexible methods for controlling surface tension. Photo-control using a photoresponsive surfactant is a potentially attractive route to accomplishing many of the tasks required in these processes. Photoresponsive surfactants typically incorporate an azobenzene group as the functional unit which experiences reversible trans-to-cis photoisomerization under different irradiation conditions. The photoisomerization usually causes a change in surface tension. Obviously, a large change in surface tension under different illumination conditions will be highly desirable in practical applications. However, the largest change in surface tension as reported in the literature is only 3 mN/m which is too small to generate any significant effect. In this presentation, we report a new class of photoresponsive surfactants which exhibit excellent performance in surface tension control. Under different illumination conditions, the change in surface tension can be as large as 11.0 mN/m. Experimental results are presented for two new photoresponsive surfactants. A discussion of experimental results follows.Singapore-MIT Alliance (SMA

    Perfectionism as a Predictor of Anxiety in Foreign Language Classrooms among Russian College Students

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    This study examined perfectionism as a multidimensional personality factor which influences foreign language learning and classroom anxiety. Hierarchical regression analyses confirmed that the two dimensions of perfectionism, adaptive and maladaptive, relate to Foreign Language Classroom Anxiety (FLCA) differently. After controlling for the effects of general anxiety, perceptions of academic performance, and self-reported English fluency, perfectionistic discrepancy (maladaptive aspect) was a significant predictor of FLCA; perfectionistic standards (adaptive aspect) was not. Measures indicated that this multidimensional nature of perfectionism affects Russian students in the context of foreign language classroom anxiety. Implications regarding the prevention and intervention of maladaptive perfectionism among students are discussed, as well as directions for future studies. These findings are important for teachers, students, and experts who may interact with FLCA and perfectionism as well as those who may personally experience it. The possible strategies to reduce anxiety could include discussing unrealistic beliefs and expectations with reference to foreign language learning, accepting mistakes as an integral part of foreign language learning as well as coaching

    Testing multiple levels of influence in the intergenerational transmission of alcohol disorders from a developmental perspective: The example of alcohol use promoting peers and μ-opioid receptor M1 variation

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    This study examined the interplay between the influence of peers who promote alcohol use and μ-opioid receptor M1 (OPRM1) genetic variation in the intergenerational transmission of alcohol use disorder (AUD) symptoms while separating the “traitlike” components of AUD symptoms from their age-specific manifestations at three ages from emerging adulthood (17–23 years) to adulthood (29–40 years). The results for males were consistent with genetically influenced peer selection mechanisms as mediators of parent alcoholism effects. Male children of alcoholics were less likely to be carriers of the G allele in single nucleotide polymorphism A118G (rs1799971), and those who were homozygous for the A allele were more likely to affiliate with alcohol use promoting peers who increased the risk for AUD symptoms at all ages. There was evidence for women of an interaction between OPRM1 variation and peer affiliations but only at the earliest age band. Peer influences had stronger effects among women who were G-carriers. These results illustrate the complex ways in which the interplay between influences at multiple levels of analysis can underlie the intergenerational transmission of alcohol disorders as well as the importance of considering age and gender differences in these pathways

    Origin of electrochemical activity in nano-Li2MnO3; Stabilization via a 'point defect scaffold'

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    Molecular dynamics (MD) simulations of the charging of Li2MnO3 reveal that the reason nanocrystalline-Li2MnO3 is electrochemically active, in contrast to the parent bulk-Li2MnO3, is because in the nanomaterial the tunnels, in which the Li ions reside, are held apart by Mn ions, which act as a pseudo 'point defect scaffold'. The Li ions are then able to diffuse, via a vacancy driven mechanism, throughout the nanomaterial in all spatial dimensions while the 'Mn defect scaffold' maintains the structural integrity of the layered structure during charging. Our findings reveal that oxides, which comprise cation disorder, can be potential candidates for electrodes in rechargeable Li-ion batteries. Moreover, we propose that the concept of a 'point defect scaffold' might manifest as a more general phenomenon, which can be exploited to engineer, for example, two or three-dimensional strain within a host material and can be fine-tuned to optimize properties, such as ionic conductivity
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