Quantum Aspects of Resolving Discrete Charges in ‘Atomistic’ Device Simulations

In ‘atomistic’ device simulation the resolving of discrete charges onto a fine grained simulation mesh can lead to problems. The sharply resolved coulomb potential can cause simulation artefacts to appear in classical simulation environments using Boltzmann or Fermi-Dirac statistics. Various methods have been proposed in an effort to reduce or eliminate artefacts such as the trapping of mobile carriers in sharply resolved Coulomb wells, however they have met with limited success. In this paper we show an alternative approach for handling discrete charges in drift diffusion ‘atomistic’ simulations by properly introducing the related quantum mechanical effects using the Density Gradient formalism. This produces the desired effect of eliminating the trapping of mobile charge in heavily doped regions of the device.     

Development of the all‐vanadium redox flow battery for energy storage: a review of technological,financial and policy aspects

The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ $0.10 kW^?1 h^?1. There is also a low‐level utility scale acceptance of energy storage solutions and a general lack of battery‐specific policy‐led incentives, even though the environmental impact of RFBs coupled to renewable energy sources is favourable, especially in comparison to natural gas‐ and diesel‐fuelled spinning reserves. Together with the technological and policy aspects associated with flow batteries, recent attempts to model redox flow batteries are considered. The issues that have been addressed using modelling together with the current and future requirements of modelling are outlined. Copyright © 2011 John Wiley & Sons, Ltd.     

Planar Chiral Phosphines Derived from [2.2]Paracyclophane

[2.2]Paracyclophane offers an exciting framework for the synthesis of planar chiral phosphines. Its rigid structure and unusual electronic properties have led to the development of a range of mono- and di-phosphines including the commercially available ligand, PhanePhos. This review discusses the synthesis and use of [2.2]paracyclophane-based phosphines and aims to give an insight into their success and failures. It is hoped that this review will encourage the design of new planar chiral phosphines for use in transition metal-mediated catalysis and organocatalysis.     

The use and nature of present-focused interventions in cognitive and behavioral therapies for depression.

To improve cognitive and behavioral therapies (CBT) for depression, several approaches recommend an increased focus on the occurrence of problems as they occur in the therapeutic relationship or in relation to the live therapy process, referred to as present-focused. A lingering question has been the degree to which CBT therapists already engage in present-focused work. This study utilized sessions from recent trials of CBT for depression and, in Phase I, raters identified present-focused interventions on a turn-by-turn basis. Phase II raters used a qualitative analysis to determine categories of present-focused interventions. Results indicated that therapists rarely focused on the therapeutic relationship; when they did, it was often transient and lacking in the elaborations suggested by newer approaches. Therapists more often performed therapy process and emotion focused interventions, but these also tended to lack elaboration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Smart carboxymethylchitosan hydrogels that have thermo‐ and pH‐responsive properties

Thermo‐responsive poly(N‐isopropylacrylamide) (poly(NIPAAm)) and pH‐responsive poly(N,N′‐diethylaminoethyl methacrylate) (poly(DEAEMA)) polymers were grafted to carboxymethylchitosan (CMC) via radical polymerization to form highly water swellable hydrogels with dual responsive properties. Ratios of CMC, NIPAAm to DEAEMA used in the reactions were finely adjusted such that the thermo and pH responsiveness of the hydrogels was retained. Scanning electron microscopy (SEM) indicated the formation of an internal porous structure for the swollen CMC hydrogels upon incorporation of poly(NIPAAm) and poly(DEAEMA). Effect of temperature and pH changes on water swelling properties of the hydrogels was investigated. It was found that the water swelling of the hydrogels was enhanced when the solution pH was under basic conditions (pH 11) or the temperature was below its lower critical solution temperature (LCST). These responsive properties can be used to regulate releasing rate of an entrapped drug from the hydrogels, a model drug, indomethacin was used to demonstrate the release. These smart and nontoxic CMC‐based hydrogels show great potential for use in controlled drug release applications with controllable on‐off switch properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41505.     

基于发电机对暂态势能集的电力系统暂态稳定快速评估

基于传统暂态能量函数方法,以简单3机3节点系统推导出一种基于发电机对暂态势能的系统暂态势能函数表达式。该暂态势能计算函数不需要全系统的网络拓扑参数或故障位置信息,仅需实时采集系统中少量的发电机机端电气状态量,计算方法简单有效。基于该发电机对暂态势能定义了受扰严重机组判别指标集,利用该指标的聚集特性在故障清除后极短时间内辨识系统的主导失稳模式,根据临界机组分群结果采用EEAC法快速计算当前故障模式下的系统暂态稳定裕度。IEEE 3机9节点、新英格兰10机39节点系统、某省级实际电网算例结果验证了该方法的正确性和有效性。     

Influence of Yb:Hf Ratio on Ytterbium Hafnate/Molten Silicate (CMAS) Reactivity

This study investigated the influence of YbO_1.5 concentration on the reactivity between YbO_1.5–HfO₂ thermal barrier coating (TBC) materials and silicate melts [calcium–magnesium aluminosilicate (CMAS), specifically 33CaO–9MgO–13AlO_1.5–45SiO₂, all in mol%]. Three thermal barrier oxides (TBO) with YbO_1.5 concentration between 30 and 80 mol% were tested at 1300°C and 1500°C. Porous pellets were used to study reaction layer growth and the behavior within infiltrated porosity. Complementary experiments examined the phase equilibria in melts containing varying quantities of the candidate TBOs. The effectiveness of reactive crystallization to limit interaction depth increased with the YbO_1.5 concentration in the TBO. The results indicate that the TBO must contain sufficient YbO_1.5 to satisfy the equilibrium between the melt and HfO₂‐based fluorite phase before YbO_1.5‐bearing silicates can precipitate. Increasing the YbO_1.5 availability leads to the crystallization of apatite, garnet, silicocarnotite, and/or cuspidine (alumino)silicates. Apatite was observed at 1300°C and 1500°C, garnet and silicocarnotite only appeared at 1300°C, and cuspidine was only evident at 1500°C. The implications for the design of CMAS‐resistant coatings are discussed in the context of the experimental results.     

PBDEs in the atmosphere of three locations in western Europe

Atmospheric concentrations of PBDEs (108 samples in total) were measured at 2 rural/semirural sites in England and 1 remote site on the west coast of Ireland in the years 2001 and 2000, respectively. Detailed analysis of the factors affecting concentrations is performed. The United Kingdom (UK) has been a major producer and user of PBDEs. Concentrations of sigmaPBDEs at Mace Head (MH), Ireland ranged between 0.22 and 5.0 pg m(-3) with a mean of 2.6 pg m(-3) and were controlled primarily by advection. sigmaPBDEs concentrations at Hazelrigg (HR), northwest England, ranged between 2.8 and 37 pg m(-3) with a mean of 12 pg m(-3) and at Chilton (CH), southwest England between 3.4 and 33 pg m(-3) with a mean of 11 pg m(-3). The average mixture of PBDEs in air was similar to that of commercial penta-BDE products. Movement of air over local/regional sources influenced concentrations of PBDEs at all sites, particularly at MH. At the two English sites during the summer, concentrations of PBDEs were strongly influenced bytemperature, indicating that air-surface exchange processes play an important role. Advection became more influential during winter, particularly at CH, where a different congener profile was observed in some samples as ambient air temperatures decreased and PBDE concentrations increased. It is hypothesized that this was due to increased emissions from diffuse combustion sources.     

Edge of Empire: Transnationalism and identity in Wellington,New Zealand,ca . 1860- ca . 1920

Aspects of transnationalism and identity in the period from the 1860s to the mid 1920s, which set in motion a form of globalization related to empire, are focused upon. The notion of 'regimes of representation' is adapted as a broad conceptual framework for exploring the role of colonial directories in establishing the identity of metropolitan commercial culture in Wellington, New Zealand. This outpost of empire is examined through a detailed analysis of the images presented in a series of directories by Kelly's and Wise. These reveal how British commerce established a strong and lasting identity in the colony through a variety of 'acts of representation'. It is concluded that colonial directories are a worthwhile but neglected source for exploring the geographies of empire.