Highly Efficient Overall Water Splitting Through Optimization of Preparation and Operation Conditions of Layered Perovskite Photocatalysts

The layered perovskite materials were found to give the high photocatalytic activity in water splitting reaction under UV irradiation, where the electronic structure of perovskite slab constructing the layered structure (the total cation valency) was the most crucial factor to the high photocatalytic activity. Both the excessive cation valency and the layered structure were required for active photocatalysts, while the slab thickness of layered perovskites had an insignificant effect on water-splitting activity. In order to identify key variables that affected photocatalytic activity and to optimize the performance of (110) layered perovskite, La₂Ti₂O₇ was modified by various methods. The optimum amount of loaded nickel had a great effect and the amount depended on the surface area of the perovskite phase. When an alkaline-earth element such as Ba, Sr, and Ca was doped on La₂Ti₂O₇, the photocatalytic activity was enhanced markedly. Introduction of an alkaline hydroxide into the reaction system as an external additive enhanced the activity further showing extremely high quantum yields close to 50%.     

城市异形排涝通道消能防冲新技术

该文针对感潮河段魁岐排涝二站?型复杂流道的不利冲刷问题,通过建立整体水工模型,研究城市异形排涝通道消能防冲新技术,提出导流坎、消力坎和消力墩联合消能防冲技术,探索其在宽幅水位变化、多工程交替运行及通航情况下的适应能力,并给出水力设计方法。研究表明,联合消能工对复杂工况适应良好,能有效解决异形排涝通道的消能防冲问题。     

向家坝水电站不同埋设方式蜗壳结构有限元分析

针对向家坝地面电站,采用三维有限元法分析比较蜗壳不同埋设方式下的流道及其外围混凝土结构的静力特性,为蜗壳埋设方式的选择提供依据。研究表明:直埋方案所需配筋最多,不经济,且可能产生贯穿性裂缝;垫层方案应力普遍较小,垫层沿水流向敷设至蜗壳45°断面的组合方案仅局部区域有较大拉应力。推荐采用垫层埋设方式或垫层敷设至蜗壳45°断面的组合埋设方式,但同时应采取有效工程措施避免局部产生贯穿性裂缝。     

钢丝帘线刚度的探讨

探讨结构不同破断力相同(近)、结构和单丝直径相同而单丝强度等级不同、结构相同单丝直径不同以及同一结构有无外缠丝等因素对钢丝帘线刚度的影响。通过数据对比表明,同一结构钢丝帘线单丝直径不同及有无外缠丝对钢丝帘线刚度影响最大,为保证轮胎的生产和质量,必须有效控制外缠结构钢丝帘线的刚度。     

Permeability characteristics of carbonated concrete considering capillary pore structure

During carbonation process, the calcium phases present in cement are attacked by CO₂ and converted into CaCO₃ and the permeability of concrete is changing due to the change in porosity. The rate of carbonation depends upon porosity and moisture content of the concrete. Especially in underground reinforced concrete structures, the interior portion of concrete surface may be exposed to carbonation and the exterior portion of concrete surface exposed to wet soil or underground water. As carbonation proceeds from outer surface into internal portion of concrete, microstructure is also changed continuously from outer surface into internal portion of concrete. Even the deteriorations in the structures due to the carbonation have been reported more, research on permeability characteristics of concrete considering carbonation and micro-structural information is very scarce.In this study, the permeability coefficient in carbonated concrete is derived by applying a capillary pore structure formation model in carbonated cement mortar and assuming that aggregates do not affect carbonation process in early-aged concrete as a function of porosity. The permeability obtained from the micro-level modeling for carbonated concrete is verified with the results of accelerated carbonation test and water penetration test in cement mortar.     

不同炭化压力下沥青炭结构特性的研究

将高温煤沥青和浸渍剂沥青在不同压力下炭化，在2500℃下对所得沥青炭进行石墨化处理；测试了所得沥青炭的体积密度、开孔率；利用扫描电子显微镜（SEM）观察了所得沥青炭的显微结构；利用XRD检测了不同炭化压力所得沥青炭石墨化处理后的石墨化度。结果表明：随着炭化压力的增大．沥青炭的体积密度增大而开孔率减小；随着炭化压力的增大沥青炭显微结构有从流线型向镶嵌型和域型转变的趋势：流线型结构沥青炭石墨化度较高；沥青中QI组分也会影响沥青炭的显微结构。     

光纤系统应用于FRP混凝土结构的实验研究

本文引入基于马赫-曾德(Mech-Zehnder)干涉原理的光纤传感检测系统,成功地进行了FRP混凝土结构的应变和振动检测.本文为光纤传感器应用于复合材料,并向工程结构的力学性能测试提供了新的技术装置,也为智能结构的研究奠定了技术基础.     

Surface properties of surfactants derived from natural products. Part 1: Syntheses and structure/property relationships—Solubility and emulsification

Several novel and some previously known, mostly sugar-based, surfactants have been synthesized and some of their surface properties have been characterized and compared with those of commercial nonylphenol ethoxylates. The surfactant solubility in water, ethanol, and dodecane was studied. The properties of these compounds as emulsification agents in systems composed of the surfactant with water/isopropyl myristate, water/rapeseed oil, and water/dodecane are presented. The aqueous solubility of the surfactants follows the general trend expected from their hydrophilic-lipophilic balance according to Griffin (HLBG), but it is also clear that the nature of the headgroup and the structure of the nonpolar part affect the solubility in a manner not aptured in the standard HLBG concept. An ester or amine group as the connecting unit between the hydrophile and the hydrophobe produces a more water-soluble surfactant than the corresponding amide derivative. Some effective emulsifiers were found. For instance, the surfactants with a dehydroabietic nonpolar group appear to be promosing emulsifiers. Most sugar-based surfactants were able to form macroemulsions of up to around 2 wt/vol% of oil. The stability of many of these amulsions was very high, extending for months.     

Effect of Vortex Restructuring on Heat Transfer in an “Inverted” Flame

The papers deals with formation of vortex structures during combustion of a fuel gas–air mixture injected vertically down through a hole in a flat plate. It has been established that the shape, position, and number of vortex cells are determined by the flow rate and composition of the fuel mixture. It is shown that as the flow rate increases from the minimum critical value for which a vortex structure arises, the number of vortex cells decreases from five or six to one. A further increase in the gas flow rate leads to transition to turbulence of the combustion product flow. The presence of a vortex structure increases the critical Reynolds number at which the flow becomes turbulent. Reverse transition to the structure with an increased number of vortex cells occurs with a delay in the gas flow rate (gas discharge hysteresis). Variation in flow rate is accompanied by bifurcation of the number of vortex cells.     

Composites based on eucalyptus tar pitch/castor oil polyurethane and short sisal fibers

Polymeric materials are being developed with renewable resources to promote industrial progress with environmentally friendly technologies. For this reason, polyurethane samples were prepared with 4,4′‐diphenylmethane diisocyanate (NCO/OH = 1), eucalyptus tar pitch (biopitch), castor oil as a polyol, and dibutyltin dilaurate as a catalyst. These materials were reinforced with different contents of short sisal fibers (0, 2.5, 5.0, 7.5, and 10.0%) and were prepared by resin‐transfer molding. The composites were characterized by IR absorption spectroscopy, thermal analysis (thermogravimetry and differential scanning calorimetry), impact resistance, scanning electron microscopy, and water absorption resistance. These materials showed hydrophobic characteristics, despite the addition of sisal fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3797–3802, 2003