Continuous Control of Charge Transport in Bi‐Deficient BiFeO3 Films Through Local Ferroelectric Switching

It is demonstrated that electric transport in Bi‐deficient Bi_1‐δFeO₃ ferroelectric thin films, which act as a p‐type semiconductor, can be continuously and reversibly controlled by manipulating ferroelectric domains. Ferroelectric domain configuration is modified by applying a weak voltage stress to Pt/Bi_1‐δFeO₃/SrRuO₃ thin‐film capacitors. This results in diode behavior in macroscopic charge‐transport properties as well as shrinkage of polarization‐voltage hysteresis loops. The forward current density depends on the voltage stress time controlling the domain configuration in the Bi_1‐δFeO₃ film. Piezoresponse force microscopy shows that the density of head‐to‐head/tail‐to‐tail unpenetrating local domains created by the voltage stress is directly related to the continuous modification of the charge transport and the diode effect. The control of charge transport is discussed in conjunction with polarization‐dependent interfacial barriers and charge trapping at the non‐neutral domain walls of unpenetrating tail‐to‐tail domains. Because domain walls in Bi_1‐δFeO₃ act as local conducting paths for charge transport, the domain‐wall‐mediated charge transport can be extended to ferroelectric resistive nonvolatile memories and nanochannel field‐effect transistors with high performances conceptually.     

Time-Dependent Reliability Analysis of Oil Derrick Structures in Mechanism Failure Mode

International Journal of Steel Structures - Most research studies on the reliability of oil derrick structures have focused on static reliability analysis. Strength degradation with time of oil...     

Effects of ε-Polylysine on Physicochemical Characteristics of Chilled Pork

The aim of this paper was to research effects of ε-polylysine (ε-PL) on physicochemical characteristics of chilled pork during storage. Chilled pork was treated with different concentrations of ε-PL. Sensory properties, total bacterial counts (TBC), pH, total volatile base nitrogen (TVB-N), metmyoglobin (MetMb) content, and α-thiobarbituric acid (TBA) of treated and control samples were analyzed periodically during refrigerated storage. Compared to control, significant reductions (p?<?0.05) for TBC, pH, TVB-N, and MetMb content of chilled pork treated with ε-PL during storage were found in this study. However, there were significant increments in sensory scores, and TBA almost did not change. TVB-N, pH, and log₁₀CFU/g showed a positive linear relationship among them. These results indicated that 1.25 % ε-PL could effectively inhibit the growth and reproduction of bacteria and enhance preservative effects of chilled pork. Thus, ε-PL has good potential to be a preservative and extends shelf life of chilled pork.     

国内包装工程研究生教育区域布局及专业研究方向探析

包装工程作为一门新兴学科,面临着众多机遇与挑战。在新的时代背景下,产业与市场对包装专业人才有了更高的要求,包装工程研究生教育也因此迅速发展起来。本研究以国内开展包装工程专业的高校为研究对象,从研究生教育的现状、开设研究生教育院校的地域分布、归属情况、研究方向等方面进行了较为详细地统计及分析,对包装工程专业学生的升学选择与就业导向有重要的引导作用,可为包装工程研究生教育的规划与发展提供一定参考。     

Glucosinolates in isaño (Tropaeolum tuberosum) tubers: qualitative and quantitative content and changes after maturity

Six varieties of isaño (Tropaeolum tuberosum), an Andean edible tuber, were analysed. The aim was to characterise qualitatively and quantitatively their content of glucosinolates and to determine concentration changes of these compounds upon delayed harvest. Additionally, exploratory assays were carried out on the effect of postharvest cold storage of the tubers as well as of a drying process imposed on blanched tuber slices. Only one glucosinolate (p‐methoxybenzyl glucosinolate) was found in the six domestic varieties analysed. Its concentration varied between 36.5 and 90.0 µmol g^?1 dry matter. This range is relatively high when compared with other edible glucosinolate‐containing vegetables. ‘Dark’ coloured tuber varieties showed higher levels than ‘light’ coloured tuber varieties at normal harvest time. Of the two varieties on which the effect of delayed harvest was studied, one showed increasing and then decreasing changes until 44 days after maturity, while the other did not show any significant change with time. Postharvest cold stored samples showed similar changes to tubers kept in soil, and glucosinolate levels in dried blanched tubers did not differ significantly from those in fresh samples. Taken together, the data indicate that the glucosinolate content of isaño is highly dependent on both the variety and the time of harvest. These parameters should be taken into account when considering isaño as a promising food source with medicinal properties for humans and animals, but also with possible adverse biological effects, all related to the presence of glucosinolates. Copyright © 2004 Society of Chemical Industry     

棉织物悬垂系数与悬垂外观形貌外张及均匀程度的关系

文章对棉织物悬垂系数F、波峰半径离散系数CVRc、波谷半径离散系数CVRt、波峰分布角离散系数CVα等指标进行了测试,采用数据拟合的方法得到了关系方程。     

Dynamic manipulation of nanomechanical resonators in the high-amplitude regime and non-volatile mechanical memory operation

The ability to control mechanical motion with optical forces has made it possible to cool mechanical resonators to their quantum ground states. The same techniques can also be used to amplify rather than reduce the mechanical motion of such systems. Here, we study nanomechanical resonators that are slightly buckled and therefore have two stable configurations, denoted 'buckled up' and 'buckled down', when they are at rest. The motion of these resonators can be described by a double-well potential with a large central energy barrier between the two stable configurations. We demonstrate the high-amplitude operation of a buckled resonator coupled to an optical cavity by using a highly efficient process to generate enough phonons in the resonator to overcome the energy barrier in the double-well potential. This allows us to observe the first evidence for nanomechanical slow-down and a zero-frequency singularity predicted by theorists. We also demonstrate a non-volatile mechanical memory element in which bits are written and reset by using optomechanical backaction to direct the relaxation of a resonator in the high-amplitude regime to a specific stable configuration.     

Psychological perspectives on the changing nature of retirement.

The concept and the process of retirement are rapidly evolving. As a result, psychologists are in a unique position to understand and explain the dynamics behind the changing face of retirement. We begin this article with a brief overview of the history of retirement and then note the various definitions used when studying retirement. We then propose that taking a temporal view of studying retirement would be most advantageous for psychologists. Psychological conceptualizations of retirement are then discussed, and we link these conceptualizations to studying the changing nature of retirement. Finally, we conclude with some suggestions for future research in the area of retirement that would be particularly relevant for psychologists to consider. (PsycINFO Database Record (c) 2011 APA, all rights reserved)