An ionic liquid‐based polymer with π‐stacked structure as all‐solid‐state electrolyte for efficient dye‐sensitized solar cells

An ionic liquid based polymer, poly(1‐ethyl‐3‐(acryloyloxy)hexylimidazolium iodide) (PEAI), was synthesized and employed as electrolyte to fabricate all‐solid‐state dye‐sensitized solar cells. The photophysical properties of PEAI were studied by UV–vis absorption spectroscopy and photoluminescence spectroscopy. PEAI exhibited significant hypochromism and red shift in UV–vis absorption spectra and large Stokes shifts in photoluminescence spectra, indicating the formation of a novel π‐stacked structure in which the imidazolium rings in the side chain were stacked. Without iodine in its preparation, DSC with PEAI electrolyte achieved a conversion efficiency of 5.29% under AM 1.5 simulated solar light irradiation (100 mW cm^?2). The side‐chain imidazolium π‐π stacking in PEAI played a key role in the holes transport from the photoanode to the counter electrode. Both the open‐circuit voltage and short‐circuit current density showed decreases with the increase in the content of iodine in PEAI electrolyte. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of MDI–BDO hard segment on pyridine-containing shape memory polyurethanes

Shape memory polymers are attractive for both science and industrial application. In this article, a series of pyridine-containing supramolecular shape memory polyurethanes (Py-SMPUs) with various diphenylmethane diisocyanate–butanediol (MDI–BDO) contents are synthesized from the 1,6-hexamethylene diisocyanate (HDI), N,N-bis(2-hydroxylethyl) isonicotinamide (BINA), BDO, and MDI. Then, they are investigated systematically using FT-IR, DSC, DMA, WAXD, and shape memory testing. The results show that the addition of MDI–BDO segment improves the strength of hydrogen bonding of Py-SMPUs. It promotes the formation of hard domains, but not influences the phase-separation structure, the intensity, and distribution of physical netpoints. In addition, the MDI–BDO segment improves the rubber modulus and drops the energy loss of Py-SMPUs. However, it does not influence the shape memory behaviors which are mainly influenced by the BINA content. If the BINA content is beyond 30 wt%, good shape memory effect can be achieved in the BINA–HDI–BDO–MDI system; and high shape recovery force can be obtained by increasing the MDI–BDO segment.     

The Impact of Infostation Density on Vehicular Data Dissemination

Vehicle-to-Vehicle and Vehicle-to-Roadside communications are going to become an indispensable part of the modern day automotive experience. For people on the move, vehicular networks can provide critical network connectivity and access to real-time information. Infostations play a vital role in these networks by acting as gateways to the Internet and by extending network connectivity. In this context, an important question is “What is the minimum number of infostations that need to be deployed in an area in order to support vehicular applications?” Optimizing infostation density is vital to understanding and reducing the cost of deployment and management. In this paper, we examine the required infostation density in a highway scenario using different data dissemination models. We start from a simple analysis that captures the required density under idealized assumptions. These models are validated by an event-driven simulator. We then run detailed QualNet simulations on both controlled and realistic vehicular traces to observe the information density trends in practical environments, and consequently propose techniques to improve dissemination performance and reduce the required infostation density.     

Novel high performance functionalized ladderlike polyphenylsilsesquioxane/bismaleimide hybrids with very good flame retardancy,thermal, and dimensional stability

Novel high performance hybrids (N-PPSQ/BDM/DBA) with very good flame retardancy, thermal, and dimensional stability as well as low dielectric constant and loss were developed, which consist of 4,4′-bismaleimidodiphenyl methane/2,2′-diallyl bisphenol A (BDM/DBA) resin and a novel functionalized ladderlike polyphenylsilsesquioxane (N-PPSQ). N-PPSQ was synthesized through the hydrolysis and condensation between phenyltrimethoxysilane and γ-aminopropyl triethoxysilane, and its structure was characterized by X-ray diffraction, nuclear magnetic resonance, gel permeation chromatography, and Fourier transform infrared. Compared with BDM/DBA resin, N-PPSQ/BDM/DBA hybrids show significantly improved integrated performances including remarkably reduced dielectric constant and loss, significantly improved flame retardancy, thermal, and dimensional stability, showing great potential for applications having harsh requirements in integrated performances. For example, in the case of the hybrid with 15 wt% N-PPSQ, its coefficient of thermal expansion in glassy and rubbery state are only about 49 and 42% of that of BDM/DBA resin, respectively; its limiting oxygen index increases from about 26.1–42.1%; while its dielectric loss is only about 87% of that of BDM/DBA resin at 1 kHz. These attractive improved properties are attributed to the variety in the cross-linked structure induced by the presence of N-PPSQ.     

工科高职院校学生普通话水平调查及提升对策探究

口语能力作为高职学生必备的职业能力之一往往被学校和学生个人所忽视。调查数据显示理工类高职院校学生的普通话水平整体偏低,普通话教学现状不容乐观。针对造成这种现状的原因提出三点解决建议。     

低温冷风磨削加工参数优化试验

绿色加工是国际国内金属加工行业的趋势,采用自行设计的低温冷风装置进行绿色磨削试验研究,测试低温冷风温度(范围:- 40至- 80℃)、压力、磨削进给量、砂轮粒度等因素对试件表面加工质量的影响,发现存在磨削最佳参数组合,且低温冷风下的磨削质量可以达到传统磨削的精磨标准.     

Effects of scale composition on oxidation kinetics of Fe-based superalloy

By oxidation weight gain method, four groups of Fe-based superalloys with different content of chromium, aluminium and silicon were tested at 1 200 °C for 500 hours. According to the oxidation weight gains, the oxidation kinetic curves were plotted, and the equations were regressed by least square method and non-linear curve fitting. The effects of different scale compositions on the morphology and oxidation kinetic law were studied further by analysis of X-ray diffraction (XRD) and scanning electron microscope (SEM). It is found that the compounded scale is composed of Cr₂O₃, Al₂O₃, SiO₂ and FeCr₂O₄, with compact structure and fine grains, possessing complete oxidation resistance at 1 200 °C, and the oxidation kinetic curve follows the power function of y=ax ^b (a>0, 0<b<1). When the compounded scale lacks Al₂O₃ or SiO₂, it becomes weak in oxidation resistance, but the oxidation kinetic curve still follows the power function with bigger parameter b. When Cr₂O₃ is absent, the kinetic curve shows two parts: the slow adding of oxidation weight gains at the beginning and the ascending line in the end. Such scale loses oxidation resistance completely.     

裂缝压力灌胶法在玉峰塔修缮工程中的应用

本文介绍了电动注胶机串联自动注胶器对玉峰塔石材裂缝压力灌胶施工工法.实践证明,该法施工速度快、裂缝修补效果良好.     

无限深透水地基上土石坝防渗墙位置对坝基渗流的影响

在无限深透水地基上修建土石坝,坝基防渗体常采用倒悬挂式防渗墙.垂直防渗墙的位置直接影响防渗墙深度和防渗效果,但以往的公式和经验不能明确其对坝基渗流量和渗透坡降的影响.为此,采用保角变换的方法,推导出无限深透水地基上土石坝坝基渗流量和下游出逸坡降公式,分析垂直防渗墙位置变化与坝基渗流的关系.以供设计人员参考.