Poly[4(5)-vinylimidazole]/polyvinylidene fluoride composites as proton exchange membranes

In the present research, the morphology and thermal chemical characteristics of composite films comprised of poly(vinylidene fluoride) (PVF2) and poly[4(5)-vinylimidazole/vinylimidazolium trifluoromethylsulfonylimide] (PVIm/VIm+TFSI-]) were studied. In these composites, conditions such as choice of solvent and drying and annealing conditions can affect the crystal habit, crystallite size and degree of crystallinity of PVF2 as well as the distribution of the minor component, poly[4(5)-VIm/VIm+TFSI-]. Such composites may have potential in fuel cells as high-temperature proton exchange membranes. When cast from either dimethylformamide (DMF) or dimethylacetamide (DMAC) at ambient temperature and dried at temperatures below 100°C, PVF2 homopolymer films and PVF2//PVIm/VIm+TFSI- composite films were obtained in which the crystallites of PVF2 were beta-phase. The films initially obtained were white, opaque films with limited strength and mechanical integrity. After heating to 200°C, both the PVF2 films and the PVF2//PVIm/VIm+TFSI- films became stronger and more transparent. X-ray diffraction showed that prior to heating the PVF2 homopolymer film was beta-phase and after heating to 200°C PVF2 was alpha-phase. This was also the case with the PVF2//PVIm/VIm+TFSI- composites. In other words, the crystalline polymorph of PVF2 in the non-heated composite films was identical to that of non-heated homopolymer PVF2, and the PVF2 polymorph in the heated composite films was identical to that of heated homopolymer PVF2 films. DSC analysis showed that the melting point of crystals in heated PVF2 was lower than that in the non-heated PVF2. This difference in Tm (melting temperature) is attributed to the fact that PVF2 beta-phase crystals have a higher melting temperature than that of the alpha-phase crystals. PVF2 composites cast from DMAC have a higher onset Tc (onset crystallization temperature) than do PVF2 composites cast from DMF. The crystallinity of PVF2 in the heated homopolymer films was lower than that in the non-heated films. The percent crystallinity in the composites was variable and depended, to some degree on the level of TFSI. In the composites cast from DMAC, the crystallinity is maximal at 15 mol% TFSI and decreases somewhat as the TFSI level is increased to 50 mol%. The crystallinity of PVF2 in the composites cast from DMF is minimal at 15 mol % TFSI and increases in concert with the TFSI level. The intimacy of the phases in the composites was assessed by evaluating the amount of PVIm/VIm+TFSI- that could be extracted with ethanol/water. It was found that, after heating, the amount of imidazole polymer that could be extracted dropped from about 81% to less that 16% of the imidazole polymer originally in the mixture. This observation coupled with the substantial transparency of the heated composites, is indicative of a nanoscopic composite in which the PVIm/VIm+TFSI- phase is intimately mixed with the amorphous phase of the majority PVF2 component

Error analysis of energy-conservative BDF2-FE scheme for the 2D Navier-Stokes equations with variable density

In this paper, we present an error estimate of a second-order linearized finite element (FE) method for the 2D Navier-Stokes equations with variable density. In order to get error estimates, we first introduce an equivalent form of the original system. Later, we propose a general BDF2-FE method for solving this equivalent form, where the Taylor-Hood FE space is used for discretizing the Navier-Stokes equations and conforming FE space is used for discretizing density equation. We show that our scheme ensures discrete energy dissipation. Under the assumption of sufficient smoothness of strong solutions, an error estimate is presented for our numerical scheme for variable density incompressible flow in two dimensions. Finally, some numerical examples are provided to confirm our theoretical results.Comment: 22 pages, 1 figure

Creative Housing Design: Promoting sustainable living in cohousing community in the UK

A cohousing community is created and managed by its residents. It is a new collaborative housing concept designed to foster meaningful relationships, closer social bonding and energy efficiency concepts. This paper aims to discuss the key principles, priorities and challenges of cohousing design process through interviews with four cohousing project architects and four members of the design group. Semi-structured interviews were carried out i) to understand residents’ thinking and behaviour change through living in the cohousing community, and ii) to establish the environmental and social sustainability in a cohousing setting. The study found that the development procedure of cohousing highly differs from the mainstream housing design. The quality of the design can potentially influence the residents’ daily life. The findings will benefit a range of groups. It will be an important reference for cohousing design standards. Also, it could potentially become the legitimate toolkit for cohousing groups.eISSN: 2398-4287 © 2018. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.DOI: https://doi.org/10.21834/e-bpj.v3i8.135

Uncertainty Modulates the Effect of Transcranial Stimulation Over the Right Dorsolateral Prefrontal Cortex on Decision-Making Under Threat

Threat is a strategy that can be used to impact decision-making processes in bargaining. Abundant evidence suggests that credible threat and incredible threat both influence the obeisance of others. However, it is not clear whether the decision-making processes under credible threat and incredible threat during bargaining involve differential neurocognitive mechanisms. Here, we employed cathodal transcranial direct current stimulation (tDCS) to deactivate the right dorsolateral prefrontal cortex (rDLPFC) to address this question while subjects allocated and reported the subjective probability of future rejection under incredible threat and credible threat. We found that application of cathodal tDCS over the rDLPFC decreased the proposer’s subjective inference of probability of rejection and the offer to the responder under incredible threat. Conversely, the same stimulation did not lead to a significant difference compared to the sham group in subjective probability and offer under credible threat. These results suggested that decision-making processes under the two types of threat during bargaining were associated with different neurocognitive substrates, because the punishment for non-compliance was uncertain under incredible threat, whereas it was certain under credible threat. We decreased activity in the rDLPFC, which is involved in decision-making processes related to bargaining under incredible threats, and observed significantly impacted behavior. The differential neurocognitive bases of subjective probability of rejection under incredible threat and credible threat resulted in different tDCS effects

Emotional Regulation, Level of Depression, Anxiety and Stress among Alcohol Abusers and Non-Abusers

The study was to examine the levels of depression anxiety and stress, as well as emotion regulation strategies among alcohol abusers and non-abusers. One hundred and fifty alcohol abusers who were admitted in department of psychiatry ward in hospital and one hundred and fifty normal people who were in general population were enrolled in the study. Depression, anxiety and stress scale (DASS-42) and emotional regulation questionnaires were used to assesses the depression, anxiety and stress reaction and emotional regulation of alcohol abusers and non-abusers. Alcohol abusers had higher level of depression, anxiety and stress reaction, as well as lower level of cognitive reappraisal and higher level of suppression compared with normal people. Cognitive reappraisal and suppression had significantly negative correlation with depression, anxiety and stress reaction in healthy people while they had no significantly correlation with depression, anxiety and stress reaction in abuser group. Further, both cognitive reappraisal and suppression significantly predicated depression, anxiety and stress reaction in healthy people while they did not predicate depression, anxiety and stress in alcohol abusers. Alcohol abusers had obvious depression, anxiety and stress reaction, as well as inappropriate copying strategies. Both cognitive reappraisal and suppression could predicate negative emotion and stress reaction in normal population but the emotional regulation failed to predicate negative emotion and stress reaction in alcohol abusers

Emotional Regulation, Level of Depression, Anxiety and Stress among Alcohol Abusers and Non-Abusers

The study was to examine the levels of depression anxiety and stress, as well as emotion regulation strategies among alcohol abusers and non-abusers. One hundred and fifty alcohol abusers who were admitted in department of psychiatry ward in hospital and one hundred and fifty normal people who were in general population were enrolled in the study. Depression, anxiety and stress scale (DASS-42) and emotional regulation questionnaires were used to assesses the depression, anxiety and stress reaction and emotional regulation of alcohol abusers and non-abusers. Alcohol abusers had higher level of depression, anxiety and stress reaction, as well as lower level of cognitive reappraisal and higher level of suppression compared with normal people. Cognitive reappraisal and suppression had significantly negative correlation with depression, anxiety and stress reaction in healthy people while they had no significantly correlation with depression, anxiety and stress reaction in abuser group. Further, both cognitive reappraisal and suppression significantly predicated depression, anxiety and stress reaction in healthy people while they did not predicate depression, anxiety and stress in alcohol abusers. Alcohol abusers had obvious depression, anxiety and stress reaction, as well as inappropriate copying strategies. Both cognitive reappraisal and suppression could predicate negative emotion and stress reaction in normal population but the emotional regulation failed to predicate negative emotion and stress reaction in alcohol abusers

Molecular oxygen-assisted in defect-rich ZnO for catalytic depolymerization of polyethylene terephthalate

Polyethylene terephthalate (PET) is the most produced polyester plastic; its waste has a disruptive impact on the environment and ecosystem. Here, we report a catalytic depolymerization of PET into bis(2-hydroxyethyl) terephthalate (BHET) using molecule oxygen (O2)−assisted in defect-rich ZnO. At air, the PET conversion rate, the BHET yield, and the space-time yield are 3.5, 10.6, and 10.6 times higher than those in nitrogen, respectively. Combining structural characterization with the results of DFT calculations, we conclude that the (100) facet of defect-rich ZnO nanosheets conducive to the formation of reactive oxygen species (∗O2−) and Zn defect, promotes the PET breakage of the ester bond and thus complete the depolymerization processed. This approach demonstrates a sustainable route for PET depolymerization by molecule-assisted defect engineering.publishedVersio