氢能——我国未来的清洁能源

首先介绍了氢能的诸多优点,例如资源丰富、来源多样性、可再生性和可储存性等,特别指出氢的可储存性使其具有和电、热不同的能源载体的用途。进而就我国能源资源情况、能源安全、环境要求以及经济可持续发展的角度说明我国发展氢能的必要性。说明发展氢能燃料电池汽车、分散供电、供热都将是我国经济持续发展的新的增长点。当前,各国制定氢能发展规划,加大发展氢能的力度,出现氢能国际化的苗头。对此,作者建议应根据我国国情特点,制定我国的氢能发展计划和目标,同时,积极参与氢能国际化活动,为我国的可持续发展争取条件。     

An economic receding horizon optimization approach for energy management in the chlor-alkali process with hybrid renewable energy generation

This paper presents a methodology for the application of receding horizon optimization techniques to the problem of optimally managing the energy flows in the chlor-alkali process using a hybrid renewable energy system (HRES). The HRES consists of solar and wind energy generation units and fuel cells to supply energy. The HRES is also connected to the grid and allows for buying or selling electricity from and to the grid. Initially, detailed models of each system component are introduced as the basis for the simulation study. Energy management strategies are then developed to realize the objectives of meeting production requirements while minimizing the overall operating and environmental costs. Sensitivity and uncertainty analyses are carried out to elucidate the key parameters that influence the energy management strategies. Finally, production demand response is integrated into the proposed methodology.     

Novel thermosetting resins for SMC applications from linseed oil: Synthesis,characterization, and properties

New thermosetting resins for applications of sheet‐molding compounds (SMCs) were successfully synthesized from linseed oil, which is the most molecularly unsaturated of all plant oils. The carbon–carbon double bonds were opened by epoxidation, followed by acrylation, and then maleinization, which provided more crosslink sites and added acid functionality on the triglyceride molecules to develop thickening. Dynamic mechanical analysis showed that the storage modulus of these new polymers was approximately 2.5 GPa at 30°C, and the glass‐transition temperature was above 100°C. During maturation the resins reached a molding viscosity quickly and stayed stable. Mechanical tests showed a flexural strength of 100 MPa and a flexural modulus of 2.8 GPa. Thermogravimetric analysis showed a single degradation ranging from 300°C–480°C, which was a result of the carbonization of the crosslinked network. These bio‐based resins are promising as replacements of some petroleum‐based resins in the SMC industry. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Chemical modification of hemp,sisal, jute,and kapok fibers by alkalization

Plant fibers are rich in cellulose and they are a cheap, easily renewable source of fibers with the potential for polymer reinforcement. The presence of surface impurities and the large amount of hydroxyl groups make plant fibers less attractive for reinforcement of polymeric materials. Hemp, sisal, jute, and kapok fibers were subjected to alkalization by using sodium hydroxide. The thermal characteristics, crystallinity index, reactivity, and surface morphology of untreated and chemically modified fibers have been studied using differential scanning calorimetry (DSC), X‐ray diffraction (WAXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), respectively. Following alkalization the DSC showed a rapid degradation of the cellulose between 0.8 and 8% NaOH, beyond which degradation was found to be marginal. There was a marginal drop in the crystallinity index of hemp fiber while sisal, jute, and kapok fibers showed a slight increase in crystallinity at caustic soda concentration of 0.8–30%. FTIR showed that kapok fiber was found to be the most reactive followed by jute, sisal, and then hemp fiber. SEM showed a relatively smooth surface for all the untreated fibers; however, after alkalization, all the fibers showed uneven surfaces. These results show that alkalization modifies plant fibers promoting the development of fiber–resin adhesion, which then will result in increased interfacial energy and, hence, improvement in the mechanical and thermal stability of the composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2222–2234, 2002     

Biobased thermosets from the free‐radical copolymerization of conjugated linseed oil

New polymeric thermosets were prepared through the bulk free‐radical copolymerization of 100% conjugated linseed oil, acrylonitrile, and divinylbenzene. Under the appropriate reaction conditions and with the appropriate curing sequence, 61–96 wt % of the oil was incorporated into the crosslinked thermosets. The resulting yellow, transparent thermosets varied from being soft and flexible to being hard and brittle. Dynamic mechanical analysis and thermogravimetric analysis showed that these thermosets had good mechanical properties and thermal stability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 979–985, 2007     

Polyesters from renewable resources: Preparation and characterization

Polyesters were synthesized with monoglycerides prepared from rubber seed oil, a renewable resource. Monoglycerides were obtained by an alcoholysis method from the oil, which was neat or modified by treatments with different amounts of maleic anhydride at 230°C. The polyester resins were subsequently prepared by the condensation polymerization of the monoglycerides with phthalic anhydride. The monoglycerides and resins were characterized by spectroscopic analysis and measurements of the physicochemical properties. The chemical resistance of the polyesters was also studied. The results revealed that the polyesters prepared from the modified monoglycerides possessed better properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3748–3755, 2006     

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     

酵母多基因表达载体在纤维素生物转化中应用

构建含酿酒酵母组成型强启动子PGK、G418抗性基因及rDNA片段的整合型载体pScIKP,利用rDNA多个同源重组位点,将外源基因以多拷贝整合到酵母染色体上,无需诱导即可持续表达;利用载体位于表达盒两端同尾酶,可插入多个基因表达盒,实现多基因稳定共表达.为检验共表达情况,反转录从绿色木霉中获得纤维素酶基因eg3和cbh2, 克隆并转化获得重组酵母菌株S.cerevisiae-ec. 该重组酵母能降解羧甲基纤维素形成水解圈;用羧甲基纤维素还原糖法和滤纸酶活力法测定酶活力,其最适温度和最适pH值与所表达单酶相似,表明共表达未影响两种酶的生物学特性;且双酶具有协同作用,能更有效降解非结晶纤维素.pScIKP载体能成功用于多个外源基因共表达和产物协同作用的研究,为构建能直接降解纤维素的酿酒酵母菌株,实现纤维素可再生能源的生物利用奠定了基础.     

地铁再生制动储能装置参数设计

为了利用地铁列车制动过程产生的再生能量,维持牵引网电压的稳定,设计一种基于列车制动的超级电容型储能装置。根据北京地铁5号线的电动列车实际参数,通过对列车制动动力学和制动特性的对比和分析,更准确地计算出列车制动过程反馈到牵引网的再生能量;分析了储能装置的物理模型,根据限制条件确定了储能装置的主要参数和阵列配置;验证分析表明,该储能装置能满足地铁制动过程中各物理量的要求。     

Biomass/polyhedral oligomeric silsesquioxane nanocomposites: Advances in preparation strategies and performances

Polyhedral oligomeric silsesquioxane (POSS) as an organic–inorganic hybrid at a molecular level, has excellent mechanical properties, thermodynamic properties, dielectric properties and so on. In recent decades, POSS has been extensively used in modification of various polymers to prepare nanocomposites with enhanced comprehensive performances. Biomass materials such as chitosan, cellulose, silk protein, collagen fibers and gelatin have excellent biocompatibility and biodegradability, which have been widely used in the fields such as biomedical, innovative environmental protection and so on. However, deficiencies including insufficient mechanical properties and rapid rate of biodegradation hampered their application. This paper briefly introduced the principal methods to synthesize POSS nanoparticles, and then focused on technologies for preparing biomass-based composites utilizing diverse functional POSSs. Finally, put forward the prospects of POSS modification technology and its future application direction. This article will have a positive guiding role for the further research and development of biomass/POSS nanocomposites.