Metal hollow sphere electrocatalysts

Metal micro-/nano hollow spheres have been widely applied in numerous fields during the last decade. This review will only focus on the synthetic strategies to synthesize hollow spherical structures in the enhancement of their electrocatalytic activity, especially the metal hollow spherical materials. We present a comprehensive overview of synthetic strategies for metal hollow spherical structures which have been approached specifically in electrochemical reactions. These synthetic methods are mainly categorized as hard templates, soft templates, sacrificial templates and without templates. The review further includes electrocatalytic approaches of hollow spherical metals in different electrochemical processes, especially the methanol electro-oxidation reaction for methanol fuel cell application and hydrogen and oxygen evolution reactions in water electrolyzer, as metal hollow spherical materials are especially applied in these specific reactions.     

Genetic Deficiency and Pharmacological Stabilization of Mast Cells Ameliorate Pressure Overload-Induced Maladaptive Right Ventricular Remodeling in Mice

Although the response of the right ventricle (RV) to the increased afterload is an important determinant of the patient outcome, very little is known about the underlying mechanisms. Mast cells have been implicated in the pathogenesis of left ventricular maladaptive remodeling and failure. However, the role of mast cells in RV remodeling remains unexplored. We subjected mast cell-deficient WBB6F1-KitW/W-v (Kit^W/Kit^W-v) mice and their mast cell-sufficient littermate controls (MC^+/+) to pulmonary artery banding (PAB). PAB led to RV dilatation, extensive myocardial fibrosis, and RV dysfunction in MC^+/+ mice. In PAB Kit^W/Kit^W-v mice, RV remodeling was characterized by minimal RV chamber dilatation and preserved RV function. We further administered to C57Bl/6J mice either placebo or cromolyn treatment starting from day 1 or 7 days after PAB surgery to test whether mast cells stabilizing drugs can prevent or reverse maladaptive RV remodeling. Both preventive and therapeutic cromolyn applications significantly attenuated RV dilatation and improved RV function. Our study establishes a previously undescribed role of mast cells in pressure overload-induced adverse RV remodeling. Mast cells may thus represent an interesting target for the development of a new therapeutic approach directed specifically at the heart.     

Correct Prediction of the Vibration Behavior of a High Power Ultrasonic Transducer by FEM Simulation

This paper presents a study on three types of finite element analyses of high power ultrasonic transducer by using the finite element commercial software called ANSYS. The transducer geometry was treated as a 2D axi- symmetric model, 3D quart and full 3D model. For all of the simulations the modeled transducer was used in modal analysis and harmonic solutions to understand its mechanical behavior and its natural frequency. A comparison was made between each type of modeling and experimental results. This comparison allows the parameters of FEM models to be iteratively adjusted and optimized and also leads to selection of the best modeling type. The achieved FEM results exhibited a remarkably high predictive potential of ANSYS in modeling and simulation and allowed control on the design and on the vibration behavior of the high power ultrasonic transducer.     

活塞气缸拍击特性及其磨损间隙变化关系

以某发动机气缸-活塞组为例,模拟了发动机气缸-活塞组中活塞的二阶拍击运动,根据二阶运动参数的模拟结果预测了气缸-活塞组件表面的磨损状态及磨损间隙。在此基础上,分析了气缸-活塞组间的间隙变化对活塞二阶运动的影响,获得了不同气缸套活塞磨损间隙的变化情况下,活塞在气缸套里做二阶运动时各种动态参数的变化规律。分析结果表明,所提出的方法能够有效预测因内燃机缸套活塞磨损间隙变化所引起活塞拍击特性的变化规律。     

Preparation of platinum-doped hollow spheres and their electrocatalytic activity in water electrolysis

Pure TiO₂ hollow spheres were prepared by using poly(styrene-methacrylic acid) latex particles as template; thereafter, titania hollow spheres were coated by platinum with an appropriate amount of choloroplatinic acid solution to obtain Pt/TiO₂ catalysts. The morphology and structure of nonstructural Pt/TiO₂ hollow spheres were characterized by BET, XRD, TGA, SEM and TEM analysis. In the samples, a remarkably uniform layer of Pt consisting of particles from 5 to 70 nm in size was formed over TiO₂ hollow spheres. We found the electrocatalytic nature of the samples by cyclic voltammetric experiment in acidic solution. The anodic peak current density of 20 wt% Pt-loaded TiO₂ hollow particles was observed 2.5 times higher than that of 5 wt% Pt/TiO₂ in the same experimental condition. Also, the anodic current density of 20 wt% Pt/TiO₂ hollow spheres calcined at various temperatures followed the order: 400 °C≈500 °C>600 °C. The electrocatalytic activity of the Pt-loaded TiO₂ hollow spheres depends on the amount of atomic platinum present in the sample; a higher concentration of platinum results in a larger current density value in anodic sweep, resulting in more oxygen production during electrolysis. Pt/TiO₂ hollow sphere catalysts have also shown long term electrocatalytic stability in acidic media.     

Designing a Collaborative Visual Analytics Tool for Social and Technological Change Prediction

This paper discussed about GreenOracle which an interdisciplinary team designed and developed. GreenOracle is a collaborative visual analytics tool for predicting global climate change's impact on US power grids and its implications for society and national security. These future scenarios provide critical assessments and information to help policymakers and stakeholders formulate a coherent and unified strategy toward shaping a safe and secure society.     

Inter-organisational knowledge transfer in social networks: A definition of intermediate ties

A social network perspective helps identify and analyse informal knowledge transfer among people and organisations with the aim to recommend organisational interventions and improvements, for example in the form of Information and Communication Technology (ICT) support. This paper particularly focuses on a key concept of social network analysis (SNA), the concept of tie strength, in an inter-organisational knowledge transfer context. Tie strength describes the strength of a social relationship. In the past, SNA literature with a knowledge management context has often emphasized the importance of strong and/or weak ties rather than of intermediate (medium strong) ties in a social network. Nevertheless, in this study, intermediate ties are identified as the dominant links among key groups of organisation in a social network. Intermediate ties also help connect otherwise weakly linked organisations. Moreover, a definition of intermediate ties in the context of knowledge management is introduced. With the help of cluster analysis and an investigation into the levels of reciprocity, intermediate ties can be clearly defined in a social network. Due to their importance for knowledge transfer in a social network, intermediate ties should be primarily supported, for example by appropriate ICT.