Challenges towards large-scale fuel cell production: Results of an expert assessment study

Fuel cell electric vehicles are a promising alternative on the way to emission-free mobility. However, there is still a great deal of uncertainty as to how this change can be implemented technologically. Despite various research and development activities on fuel cells in the past two decades, a real breakthrough of fuel cell technology has not yet been reached. The aim of this paper is therefore to identify barriers to a commercialized production of PEM fuel cell stacks. For this purpose, a comprehensive expert study is performed, consisting of a qualitative, exploratory and a quantitative, hypothesis-confirming step. As a result, technical and non-technical barriers are examined and described in this paper. A cost estimation of today's actual manufacturing cost is presented as identified in the study. Conclusively, future research topics and needs for action are derived.     

食品中全氟化合物分析技术研究进展

全氟化合物(perfluorinated compounds,PFCs)是一类人工合成的脂肪烃类化合物,自上个世纪50年代合成以来,该类化合物以其优良的稳定性及表面活性作为加工助剂被应用于多种民用及工业领域,如纺织品、灭火器和油漆等行业。近些年来越来越多的调查研究发现,在空气、沉积物、饮用水、海水和食品中检测出全氟类化合物。膳食作为人体暴露PFCs的重要途径之一,已受到了各国研究人员的重视。本文综述了食品中PFCs的检测技术的研究进展,讨论了不同食品中PFCs的前处理及检测方法,当前主要采用离子对液液萃取和液固萃取,WAX柱净化提取液,液相色谱-质谱联用技术定量分析食品中的PFCs。由于食品中PFCs处于痕量水平,对该类物质的检测方法中空白本底的控制尤为重要。另外,全氟化合物存在的多种同分异构体之间的差异将是研究人员对其准确监测的困难之一。     

利用糖类成分评价我国油菜原蜜的品质

目的以油菜原蜜为研究对象,通过测定其中果糖、葡萄糖、蔗糖和麦芽糖的含量评价我国大宗原蜜的品质。方法采用高效液相色谱示差折光法测定我国10个省份共36种油菜原蜜样品中果糖、葡萄糖、蔗糖和麦芽糖的含量。结果用液相色谱方法测定蜂蜜中的果糖、葡萄糖、蔗糖和麦芽糖,最低检测限分别为0.079 g/100 g、0.018 g/100 g、0.037 g/100 g及0.094 g/100 g,定量检测限分别为0.263 g/100 g、0.061 g/100 g、0.124 g/100 g及0.314 g/100 g。36种油菜原蜜中果糖、葡萄糖、蔗糖和麦芽糖的含量范围分别为26.00~38.16g/100 g、23.65~39.68 g/100 g、0.14~0.62 g/100 g及1.09~3.10 g/100 g。结论油菜原蜜样品中的蔗糖含量都符合我国蜂蜜国家标准,但其中31.8%的样品中葡萄糖和果糖总量低于国家标准。目前,我国大宗蜂蜜不存在人为掺入蔗糖的问题。     

Development of a cell-based antioxidant activity assay using dietary fatty acid as oxidative stressor

The existing cellular antioxidant activity (CAA) assays always use chemical stressors [e.g. 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH)] to initiate oxidative stress (OS), which is not accordance with the pathology of OS-related diseases. In contrast to previous cell models, an oleic acid (OA)-induced OS model of the HepG2 cells was developed in the current work. The antioxidant activities (AAs) of the 16 flavonoid standards in the CAA_OA assay were significantly different from the results of the CAA_AAPH and peroxyl radical-scavenging assays (PRSA). The AAs of these flavonoids in the PRSA were significantly associated with those of the CAA_AAPH assay (r = 0.848, P < 0.01). On the other hand, isoflavones and epicatechin could significantly attenuate the OS in the CAA_OA assay. However, the three flavonoids had no quantifiable AA in CAA_AAPH and PRSA. The aforementioned results suggest that the CAA_OA assay can probably better reflect the AAs of samples in biological systems.     

两种织纹螺肌肉蛋白的电泳鉴别

利用聚丙烯酰胺凝胶电泳(SDS-PAGE)对有毒的光织纹螺(Nassariusrutilans)和无毒的西格织纹螺(Nassariussiquinjorensis)的肌肉蛋白做鉴别分析。实验采用四种不同抽提液对肌浆蛋白和肌原纤维蛋白进行提取。肌肉蛋白经电泳后以考马氏亮蓝染色并对蛋白图谱作对比分析。根据蛋白条带的数量、迁移率及浓度等特点,比较得出两种织纹螺的差异条带。综合比较得出,前者的肌肉蛋白特异条带为34.9kDa、32.7kDa,后者的特异条带为36.0kDa。结果表明,以SDS-PAGE电泳法可实现对该两种织纹螺的初步鉴别。     

Alternative method for generating hydrogen through high-energy mechanical milling using magnesium and methanol

This paper presents a new way to generate hydrogen through mechanical milling. Hydrogen was generated “in-situ” inside a stainless steel container where methanol and magnesium were utilized. The methanol atoms due to the high-impact process were broken to obtain hydrogen. In this same process, magnesium was selectively reacted with oxygen to form the corresponding oxide and hydrogen remain in gas form. Relatively short milling times were programmed. After the programmed times, hydrogen from the stainless steel container through liquid displacement was measured. Likewise, solids were analyzed before and after hydrogen production using XRD and SEM techniques. The volume of hydrogen was a function of the programmed milling time; the average values between 160 and 310 mL were obtained when the most appropriate amounts of magnesium and methanol were used. Only magnesium oxide was formed as by-product. XRD analyses demonstrated the transformation of magnesium and methanol to generate hydrogen.     

Phosphorus and iron doped nitrogen-containing carbon derived from biomass for oxygen reduction under various pH conditions

Various catalysts were synthesized by incorporating phosphorus and iron into nitrogen-containing carbon derived from shrimp shell with pyrolysis. These catalysts had high specific surface area, uniform atomic doping and various active sites, which resulted in the high kinetics activity towards oxygen reduction reaction (ORR) under various pH conditions. Based on different doping sources to analyse ORR activity, phosphorus-doped catalyst was suitable for alkaline medium and iron doping for acidic medium, while their synergistic effect induced the highest ORR activity in neutral medium. Besides, the stability measurements investigated their abilities for application. Introducing iron into nitrogen-containing carbon could gradually strengthen the long-term stability for different catalysts in various pH conditions. Especially, phosphorus doping promoted the best ORR performance in alkaline condition with an extremely poor stability, which could be overcome by further adding iron. This work provides a strategy for the doped biomass-based carbon to accommodate different fuel cells.     

纳米SiO2／TiO2光催化降解空气中甲醛的研究

采用共沉淀方法制备了Si共掺杂的SiO2／TiO2光催化复合粉末,将其负载于活性炭（ACF）上。在流动化床中,考察了煅烧温度、煅烧时间、Si掺杂量、负载次数、光照条件以及甲醛初始浓度对该复合剂光催化降解甲醛效率的影响。结果发现当Si：Ti：1：4、SiO2／TiO2复合催化剂煅烧时间4h、煅烧温度400℃,ACF上负载1次,18w紫外光照射时,甲醛的降解效果最佳,对初始浓度小于0．4mg／L的甲醛气体,降解率可达90％左右。     

茚三酮法测定蜂蜜及果葡糖浆中的氨基酸含量

蜂蜜是以葡萄糖和果糖为主要成分的天然保健品。果葡糖浆具有和蜂蜜相似的糖类成分,依据糖含量及感官指标很难区别蜂蜜和果葡糖浆。本文根据蜂蜜及果葡糖浆中的氨基酸含量差异,采用茚三酮显色法检测5种蜂蜜、13种果葡糖浆及蜂蜜与果葡糖浆混合物的氨基酸含量,建立快速评价蜂蜜品质的新方法。测定结果表明,茚三酮法测定氨基酸含量具有良好的线性(R2=0.9992),准确性(回收率96.3%～101.1%)和重复性(标准偏差0.8%～5.8%)。5种蜂蜜中氨基酸含量均高于200μg/g,而13种果葡糖浆中氨基酸的含量介于10.1～47.8μg/g之间;蜂蜜和果葡糖浆混合物中氨基酸含量随果葡糖浆掺入量的增加而线性减少,这说明可通过茚三酮法检测蜂蜜中的氨基酸含量,实现蜂蜜品质的快速评价。