Optimization of selective acidolysis pretreatment for the valorization of wheat straw by a combined chemical and enzymatic process

The cover image is based on the Original Article Optimization of selective acidolysis pretreatment for the valorization of wheat straw by a combined chemical and enzymatic process by Yong Xu, Jianming Guo, Shizhong Zhang et al., https://doi.org/10.1002/jctb.6251 .

     

火星表面散射光对太阳电池发电影响研究

火星表面存在大气,太阳光经过大气后,部分被大气吸收,部分光到达火星表面,形成直射光,还有一部分光被空气尘埃阻挡发生漫反射,形成散射光,地面反射的光也是散射光光源的一部分。直射光和散射光均会对火星车太阳电池发电产生影响。分析了火星探测漫游者(MER)任务中火星车太阳翼实际发电情况,调研了火星表面直/散光辐照数据,进行了地面直/散光辐照试验,并对上述三类数据进行比对,给出火星表面散射光对太阳电池发电影响的定量结果。     

选择相溶解技术制备微/纳结构的研究进展

选择相溶解技术是一种简单、经济、有效的微/纳结构制备方法,尤其是在超长径比、超深宽比和单晶微/纳结构制备方面具有独特的优势。其原理是提取两相或多相合金中的微/纳结构,尺寸调控主要在预制合金形成的过程中进行。本文在明确区分选择相溶解技术和去合金化的基础上,首次详细综述了选择相溶解技术在纳米颗粒、微/纳丝、微/纳米孔和微/纳通道制备方面的研究进展,并结合本课题组研究工作完善了其工艺流程,拓宽了其应用范围,丰富了微/纳结构种类,为该技术在微/纳结构制备领域的广泛应用奠定了基础。     

High-performance photocatalysts for the selective oxidation of alcohols to carbonyl compounds

With an increase in awareness about the need for green chemistry, there is a shift in focus towards identifying eco-compatible technologies that can improve product yield and eliminate the use or generation of hazardous compounds. An immediate practical example of such an approach is the development of sustainable methods for alcohol oxidation as alternatives to the current processes that are energy intensive and rely on ecotoxic chemicals. In this regard, heterogeneous photocatalysis has been identified as a robust technique to catalyze reactions under benign conditions, which would otherwise require harsh synthesis routes. With the advent of materials sciences and nanotechnology, there has been a tremendous increase in the scope of applicability of photocatalysis in fine chemicals synthesis. Though an attractive choice, much of the fundamental information pertaining to catalyst activity, selectivity and reaction conditions for optimum conversion are still to be investigated for most of these systems. To this end, this review will encompass recent achievements in the selective photocatalytic oxidation of alcohols by harnessing solar radiation as a viable source of energy. The discussion will be arranged based on common types of photocatalysts reported in literature, namely metal oxides (eg, TiO₂ and ZnO, Nb₂O₅), sulphides (eg, CdS, CuS, and Bi₂S₃), and carbonaceous photocatalysts (eg, g-C₃N₄). Several such candidates for photocatalysts will be discussed critically with the aim of providing useful insight into developing selective photocatalysts that can oxidize alcohols via eco-friendly pathways along with high yields.     

Niobium and iron co-doped titania nanobelts for improving charge collection in dye-sensitized TiO2 solar cells

Niobium (Nb) and iron (Fe) co-doped titanium oxide nanobelts were prepared in a one-pot alkaline hydrothermal process followed by calcination treatment, and evaluated in TiO₂ nanoparticle-based composite anodes for dye-sensitized solar cells. Addition of Nb and Fe species caused an increase in donor density and trap-mediated charge transition, as characterized by electrochemical and photoluminescence analyses. Under illumination with simulated solar light, the co-doped single-crystalline nanobelts promoted photocurrent yield and open-circuit voltage, because they facilitate electronic conduction and chemical capacitance in the composite anodes. This improved photovoltaic performance is associated with the enhanced charge collection efficiency, mechanistically attributed to rapid electron transport and prolonged electron lifetime via shallow trapping sites. Results demonstrate that the Nb and Fe co-doped titania nanobelts are effective to provide longer electron diffusion lengths and favor charge accumulation during cell operation.     

Prevailing Research Trends in Carbon Nanohorn and Polymer-based Hybrids

This review outlines research progress on carbon nanohorn (CNH) and polymer/CNH hybrids including structure, properties, application, and future stance. Carbon nanohorn is a type of nanocarbon existing as dahlia-like, bud-like, and seed-like structures. Most widely known form is single-walled carbon nanaohorn with diameter of ～5?nm and tube length ～50?nm. Polymers such as polystyrene, polyaniline, polythiophene, poly(vinylalcohol), poly(methylmethacrylate), poly(ethyleneglycol), polycaprolactone, polyimide, poly(2-aminopyridine), and nylon have been interacted with CNH using various techniques. Structural and physical properties of fine-tuned carbon nanohorn and polymer/CNH hybrids have been used for versatile applications such as dye-sensitized solar cell, supercapacitor, drug delivery, fuel cell, and sensors.     

A comprehensive review of solar thermoelectric cooling systems

The negative environmental impacts of burning fossil fuels have forced the energy research community seriously to consider renewable sources, such as naturally available solar energy. This paper provides an overview of solar thermoelectric (TE) cooling systems. Thus, this review presents the details referring to TE cooling parameters and formulations of the performance indicators and focuses on the development of TE cooling systems in recent decade with particular attention on advances in materials and modeling and design approaches. Additionally, the TE cooling applications have been also reviewed in aspects of electronic cooling, domestic refrigeration, air conditioning, and power generation. Finally, the possibility of solar TE cooling technologies application in “nearly zero” energy buildings is briefly discussed, and some future research directions are included. This research shows that TE cooling systems have advantages over conventional cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no working fluid, being powered by direct current, and easily switching between cooling and heating modes.     

严寒地区单体建筑太阳能-相变墙系统蓄热特性研究

利用太阳能对水加热并通入相变墙进行蓄热，对减少严寒地区单体建筑供热能耗有重要意义。以大庆市某单体建筑为例，结合该地区太阳能分布特点及建筑热负荷大小，对适用于该地区的太阳能-相变墙系统进行集热与储热能力计算，并采用CFD方法研究单一工况下该系统的热工变化规律及不同热水参数、换热管规格对相变墙蓄热特性的影响。结果表明：该相变墙热稳定性良好，但受自然对流影响，底部相变材料熔化较慢；管径DN25、入口流速0.3m/s、供水温度310.15K、回水温度309.15K、管间距107mm可使相变材料在4小时内完成蓄热，平均节能率为31.8%。研究结果可望为降低严寒地区建筑供热能耗提供新思路。     

退火工艺对激光选区熔化成形Ti6Al4V合金组织及室温力学性能的影响

以Ti6Al4V球形粉末为原料,利用激光选区熔化成形方法制备了Ti6Al4V合金试样,采用光学显微镜、扫描电镜及力学性能测试等手段,研究了退火工艺对Ti6Al4V合金室温力学性能及组织的影响规律。结果表明: SLM成形沉积态Ti6Al4V合金室温抗拉强度超过1200 MPa,而平均断后伸长率仅为4.0%;在650 ℃下进行真空退火处理,合金的抗拉强度仍保持在1200 MPa左右,规定塑性延伸强度R_p0.2高于1150 MPa,但试样的断后伸长率<10%;而在750及800 ℃下进行真空退火处理,合金试样的抗拉强度降至1100 MPa左右,规定塑性延伸强度高于1050 MPa,伸长率达到甚至超过10%,材料的综合强韧性得到明显提升。随着真空退火加热温度和保温时间的增加,SLM成形Ti6Al4V合金原始β晶界逐渐变模糊,晶粒趋向于等轴化。与此同时,快速冷却转变的α′针状马氏体未出现明显地粗化。