Chemically Ordered Pt–Co–Cu/C as Excellent Electrochemical Catalyst for Oxygen Reduction Reaction

This paper reveals the ordered structure and composition effect to electrochemical catalytic activity towards oxygen reduction reaction (ORR) of ternary metallic Pt–Co–Cu/C catalysts. Bimetallic Pt-Co alloy nanoparticles (NPs) represent an emerging class of electrocatalysts for ORR, but practical applications, e.g. in fuel cells, have been hindered by low catalytic performances owning to crystal phase and atomic composition. Cu is introduced into Pt-Co/C lattices to form PtCoxCu1−x/C (x = 0.25, 0.5 and 0.75) ternary-face-centered tetragonal (fct) ordered ternary metallic NPs. The chemically ordered Pt–Co–Cu/C catalysts exhibit excellent performance of 1.31 A mg−1 Pt in mass activity and 0.59 A cm−2 Pt in specific activity which are significantly higher than Pt-Co/C and commercial Johnson Matthey (JM) Pt/C catalysts, because of the ordered crystal phase and composition control modified the Pt-Pt atoms distance and the surface electronic properties. The presence of Cu improves the surface electronic structure, as well as enhances the stability of catalysts

Theoretical investigation of the thermal performance of a novel solar loop-heat-pipe façade-based heat pump water heating system

The aim of the paper was to present a dedicated theoretical investigation into the thermal performance of a novel solar loop-heat-pipe façade based heat pump water heating system. This involved thermo-fluid analyses, computer numerical model development, the model running up, modelling result analyses and conclusion. An energy balance network was established on each part and the whole range of the system to address the associated energy conversion and transfer processes. On basis of this, a computer numerical model was developed and run up to predict the thermal performance of such a system at different system configurations, layouts and operational conditions. It was suggested that the loop heat pipes could be filled with either water, R134a, R22 or R600a; of which R600a is the favourite working fluid owing to its relatively larger heat transfer capacity and positive pressure in operation. Variations in the system configuration, i.e., glazing covers, heat exchangers, would lead to identifiable differences in the thermal performance of the system, represented by the thermal efficiency and COP. Furthermore, impact of the external operational parameters, i.e., solar radiation and ambient air temperature, to the system's thermal performance was also investigated. The research was based on an innovative loop-heat-pipe façade and came up with useful results reflecting the thermal performance of the combined system between the façade and heat pump. This would help promote development and market penetration of such an innovative solar heating technology, and thus contribute to achieving the global targets in energy saving and carbon emission reduction

Admissibility of Estimated Regression Coefficients Under Generalized Balanced Loss

There are some discussions concerning the admissibility of estimated regression coefficients under the balanced loss function in the general linear model. We study this issue for the generalized linear regression model. First, we propose a generalized weighted balance loss function for the generalized linear model. For the proposed loss function, we study sufficient and necessary conditions for the admissibility of the estimated regression coefficients in two interesting linear estimation classes.Ведуться дєякі дискусії щодо допустимості оцінєних коєфіцієнтів регресії для збалансованої функції втрат у загальній лінійній моделі. В роботі вивчається ця проблема для узагальненої лінійної моделі регресії. Так, запропоновано узагальнену зважену функцію втрати балансу для узагальненої лінійної моделі. Для вказаної функції втрат ми вивчаємо необхідні та достатні умови допустимості оцінених коефіцієнтів регресії для двох цікавих лінійних випадків оцінювання

Diesel exhaust and house dust mite allergen lead to common changes in the airway methylome and hydroxymethylome.

Exposures to diesel exhaust particles (DEP) from traffic and house dust mite (HDM) allergens significantly increase risks of airway diseases, including asthma. This negative impact of DEP and HDM may in part be mediated by epigenetic mechanisms. Beyond functioning as a mechanical barrier, airway epithelial cells provide the first line of immune defense towards DEP and HDM exposures. To understand the epigenetic responses of airway epithelial cells to these exposures, we exposed human bronchial epithelial cells to DEP and HDM and studied genome-wide 5-methyl-cytosine (5mC) and 5-hydroxy-methylcytosine (5hmC) at base resolution. We found that exposures to DEP and HDM result in elevated TET1 and DNMT1 expression, associated with 5mC and 5hmC changes. Interestingly, over 20% of CpG sites are responsive to both exposures and changes in 5mC at these sites negatively correlated with gene expression differences. These 5mC and 5hmC changes are located in genes and pathways related to oxidative stress responses, epithelial function and immune cell responses and are enriched for binding sites of transcription factors (TFs) involved in these pathways. Histone marks associated with promoters, enhancers and actively transcribed gene bodies were associated with exposure-induced DNA methylation changes. Collectively, our data suggest that exposures to DEP and HDM alter 5mC and 5hmC levels at regulatory regions bound by TFs, which coordinate with histone marks to regulate gene networks of oxidative stress responses, epithelial function and immune cell responses. These observations provide novel insights into the epigenetic mechanisms that mediate the epithelial responses to DEP and HDM in airways