Azobenzene photomechanics: prospects and potential applications

The change in shape inducible in some photo-reversible molecules using light can effect powerful changes to a variety of properties of a host material. This class of reversible light-switchable molecules includes molecules that photo-dimerize, such as coumarins and anthracenes; those that allow intra-molecular photo-induced bond formation, such as fulgides, spiro-pyrans, and diarylethenes; and those that exhibit photo-isomerization, such as stilbenes, crowded alkenes, and azobenzenes. The most ubiquitous natural molecule for reversible shape change, however, and perhaps the inspiration for all artificial bio-mimics, is the rhodopsin/retinal protein system that enables vision, and this is the quintessential reversible photo-switch for performance and robustness. Here, the small retinal molecule embedded in a cage of rhodopsin helices isomerizes from a cis geometry to a trans geometry around a C=C double bond with the absorption of just a single photon. The modest shape change of just a few angstroms is quickly amplified and sets off a cascade of larger shape and chemical changes, eventually culminating in an electrical signal to the brain of a vision event, the energy of the input photon amplified many thousands of times in the process. Complicated biochemical pathways then revert the trans isomer back to cis, and set the system back up for another cascade upon subsequent absorption. The reversibility is complete, and many subsequent cycles are possible. The reversion mechanism back to the initial cis state is complex and enzymatic, hence direct application of the retinal/rhodopsin photo-switch to engineering systems is difficult. Perhaps the best artificial mimic of this strong photo-switching effect however in terms of reversibility, speed, and simplicity of incorporation, is azobenzene. Trans and cis states can be switched in microseconds with low-power light, reversibility of 10⁵ and 10⁶ cycles is routine before chemical fatigue, and a wide variety of molecular architectures is available to the synthetic materials chemist, permitting facile anchoring and compatibility, as well as chemical and physical amplification of the simple geometric change. This review article focuses on photo-mechanical effect taking place in various material systems incorporating azobenzene. The photo-mechanical effect can be defined as reversible change in shape by absorption of light, which results in a significant macroscopic mechanical deformation, and reversible mechanical actuation, of the host material. Thus, we exclude simple thermal expansion effects, reversible but non-mechanical photo-switching or photo-chemistry, as well as the wide range of optical and electro-optical switching effects for which good reviews exist elsewhere. Azobenzene-based material systems are also of great interest for light energy harvesting applications across much of the solar spectrum, yet this emerging field is still in an early enough stage of research output as to not yet warrant review, but we hope that some of the ideas put forward here toward promising future directions of research, will help guide the field.     

Advances and future prospects in copper electrowinning

In recent years research on the electrowinning of copper has led to a number of significant advances. These developments include improved mass transfer and higher current density operation through air sparging, reduced anode overvoltage in the conventional cell as a result of cobalt(II) addition to the electrolyte or the use of alternative types of anodes, and the production of high quality cathodes in the electrowinning of copper from solvent extraction strip liquor. The fluidized-bed cathode offers the possibility of continuous electrowinning as well as the direct electrowinning of copper from dilute solutions. The problem of high power consumption may find its solution in the adoption of an alternate anode reaction or in the electrowinning of copper (I) electrolytes. Noteworthy is the development of unique electrowinning cells in conjunction with the hydrometallurgical treatment of copper concentrates. These cells utilize cuprous or ferrous anodic oxidation with the resulting cupric or ferric ions being active lixiviants of sulphide copper minerals. The numerous advances combined with the increasing tonnage of copper being produced by the electrowinning route ensure an interesting and promising future for this process.     

微/纳反应器的研究现状及发展前景

微化工系统已经成为解决许多高新技术领域的化工过程问题的关键,而微反应器作为微化工系统的核心已经成为研究的热点之一。本文着重分析了微反应器的概念、分类及其性能优势,总结出近年来国内外微反应器的研究发展情况和存在的问题,并对发展前景进行了展望。     

氯碱化工产业发展的建议及展望

介绍了金泰氯碱化工有限公司面临的问题,提出了企业发展的思路及建议,认为通过加强规模优势、合理布局、经济结构、提高产品技术附加值,延伸产业链、发展低碳经济、循环经济、实现上市融资等措施才能发展成为一流的大型氯碱企业。     

Desalination in Australia operational experience and future prospects

To provide high quality fresh water to meet peak demands at times of drought in large population centres and to satisfy the requirements for water standards in industrial processes are perhaps the prime attractions of sea water desalination plants. Australia, the driest of earth's continents, will probably have a need for such water supply supplementation and industrial process application long before desalting is applied generally to agriculture or rural production. As the cost of fossil fuel gradually increases, it would also seem likely that the thermal energy required for desalting will come from nuclear fuels. In this paper the existing fresh water resources of the Australian continent are briefly surveyed. Present costs associated with supplying fresh water for industrial and domestic consumption to selected communities at representative locations of the Australian continent are assessed. The technology and economics of large scale sea water desalination plants operating on thermal cycles are discussed. In particular, the multi-stage flash evaporator principle is reviewed and its potential discussed. Consideration is given to the advantages and disadvantages of nuclear powered heat sources. Proposals are made for the control and conjunctive use of reservoirs and desalination plants. The optimisation of desalination plant size and its integration with reservoir storage schemes in two potential Australian locations is discussed.     

Recent progress and future prospects of oil-absorbing materials

Oil and organic solvent contamination, derived from oil spills and organic solvent leakage, has been recognized as one of the major environmental issues imposing a serious threat to both human and ecosystem health. Among the various presented technologies applied for oil/water separation, oil absorption process has been explored widely and offers satisfactory results especially with surface modified oil-absorbing material and/or hybrid absorbents. In this review, we summarize the recent research activities involved in the designing strategies of oil-absorbing absorbents and their application in oil absorption. Then, an extensive list of various oil-absorbing materials from literature, including polymer materials, porous inorganic materials and biomass materials, has been compiled and the oil adsorption capacities toward various types of oils and organic solvents as available in the literature are presented along with highlighting and discussing the various factors involved in the designing of oil-absorbing absorbents tested so far for oil/water separation. Finally, some future trends and perspectives in oil-absorbing material are outlined.     

Carbon containing castables: current status and future prospects

Abstract

Measures to overcome the main technical di fficulties hindering the development and application of carbon containing castables are discussed. The aqueous wettability and dispersion properties of graphite can be improved by coating with materials such as carbides (SiC) and oxides (Al₂O₃, TiO₂, SiO₂, MgO, ZrO₂) or by forming micropellets / briquettes. Thick and dense crack free coatings are needed not only to improve the aqueous wettability and dispersion of graphite, but also its oxidation resistance. Small and dense micropellets or briquettes enable a homogeneous distribution of graphite in the matrix to be achieved, along with acceptable mechanical strength and corrosion resistance. Coating techniques have also been used to improve the hydration resistance of aluminium based antioxidants, but detailed studies in this area are still needed. The main binder systems are currently based on superfine silica fume and hydratable alumina as these do not form low melting phases in castables. As well as developing the existing coating and micropellet/briquette fabrication techniques, future work will continue to seek novel methods of incorporating graphite, and will begin to investigate installation methods and drying and heating schedules.     

8月份国内硫磺市场分析及后市展望

1 硫磺市场分析 8月份国内硫磺市场上涨的趋势已经开始放缓,8月下旬硫磺人民币市场价格开始小幅下滑,尤其以青岛、天津为代表的北方市场更为突出.近期人民币市场价格回落的主要原因是进口贸易商利润缩水,在目前硫磺下游市场低靡的情况下,贸易商为了规避风险已经很少追求前期的较高利润,多采取短线操作.     

Nanomedicine: application areas and development prospects

Nanotechnology, along with related concepts such as nanomaterials, nanostructures and nanoparticles, has become a priority area for scientific research and technological development. Nanotechnology, i.e., the creation and utilization of materials and devices at nanometer scale, already has multiple applications in electronics and other fields. However, the greatest expectations are for its application in biotechnology and health, with the direct impact these could have on the quality of health in future societies. The emerging discipline of nanomedicine brings nanotechnology and medicine together in order to develop novel therapies and improve existing treatments. In nanomedicine, atoms and molecules are manipulated to produce nanostructures of the same size as biomolecules for interaction with human cells. This procedure offers a range of new solutions for diagnoses and "smart" treatments by stimulating the body's own repair mechanisms. It will enhance the early diagnosis and treatment of diseases such as cancer, diabetes, Alzheimer's, Parkinson's and cardiovascular diseases. Preventive medicine may then become a reality.     

中国仿瓷餐具业的发展与前景

详细介绍了中国仿瓷餐具业的发展,行业现状,分析了国内外市场环境和产业发展面临的机遇和问题,并对发展前景与趋势作了预测.     

生物医学材料的应用现状及发展前景

由于生物医学材料是无毒副作用、生物相容性良好、耐腐蚀性能优越的医用材料,越来越受到广大科技研究工作者的重视。近20年,国内外特别是一些发达国家对生物材料的研究和开发得到飞速的发展。本文详细阐述了生物医学材料的分类及发展前景。     

老井侧钻技术发展前景分析

老井侧钻是提高单井产量、开发剩余油气藏的有效手段,可以大幅度降低投资成本的同时提高采收率。随着国内外油田对老井侧钻技术的应用日益增多,暴露了一些侧钻的难点,应该根据不同油气田的实际情况筛选合适的老井进行侧钻。     

轮胎行业大数据库发展前景

随着计算机网络的不断发展,人们利用网络进行信息交流的应用范围越来越广泛。信息管理系统中大型数据库管理系统的应用,不仅能够提高信息管理系统的性能,而且对提升信息的利用率也具有重要的作用。在轮胎行业对大数据库的应用,优化了轮胎的生产、运输和销售的各个环节。     

Bioresorbable and degradable behaviors of PGA: Current state and future prospects

Polyglycolic acid (PGA) is a class of semicrystalline, bioresorbable polymers that have been widely used in a number of applications. No other bioresorbable materials can fully replace PGA in tissue engineering. Understanding degradation mechanisms in PGA is important for improving the efficiency and effectiveness in various fields including implantation. This review begins with a discussion on terminology of polymer degradation and hydrolytic degradation mechanism with a delineative model. This review also focus on previous degradation studies taking advantage of its fast-degrading behavior and the mechanism behind hexafluoroisopropanol (HFIP) being the sole solvent for PGA. Finally, the merits of PGA are discussed with many potential future applications along with their associated challenges.     

纤维素乙醇发展的局限及展望

纤维素生物乙醇具有资源可持续性以及环境友好性等优点,已经成为世界各国新能源的重要发展方向。从生产流程、能耗和政策支持3个方面重点阐述了限制其发展的原因,同时对我国纤维素生物乙醇的发展进行展望,为该领域的研究和应用提供参考。