Daily concentrations of trace metals in aerosols in Beijing, China, determined by using inductively coupled plasma mass spectrometry equipped with laser ablation analysis, and source identification of aerosols

This paper describes the daily concentrations of trace metals and ionic constituents in the aerosol of Beijing, China from March 2001 to August 2003. Daily PM10 concentrations were also measured from September 2001 to August 2003. The daily average PM10 concentration at Beijing, China from September 2001 to August 2003 was 171+/-117 microg m(-3) (n = 673), which is 5-fold higher than at Yokohama, Japan. Trace metal concentrations were analyzed by using inductively coupled plasma mass spectrometry equipped with a laser ablation sample introduction (LA/ICP-MS), which is a rapid and simultaneous method for multi-element analysis. The daily average metal concentrations in TSP in Beijing from March 2001 to August 2003 were: Al: 3.5+/-2.4 (n = 727), Ti: 0.47+/-0.35 (n = 720), V: 0.013+/-0.010 (n = 716), Cr: 0.019+/-0.015 (n = 618), Mn: 0.24+/-0.16 (n = 730), Fe: 5.5+/-3.9 (n = 728), Co: 0.0046+/-0.0055 (n = 629), Ni: 0.022+/-0.024 (n = 680), Cu: 0.11+/-0.11 (n = 660), Zn: 0.77+/-0.60 (n = 726), As: 0.048+/-0.047 (n = 731), Se: 0.010+/-0.010 (n = 550), Cd: 0.0068+/-0.0082 (n = 709), Sb: 0.033+/-0.036 (n = 687), and Pb: 0.43+/-0.50 (n = 728) (unit, microg m(-3)). All the metal concentrations in TSP in Beijing, China were 1.7-21.8 times higher than those in TSP in the center of Tokyo, Japan. Notably, As concentrations in TSP in Beijing were 20-fold higher than those in Tokyo. Source identification of aerosols in Beijing was carried out by using the chemical mass balance (CMB) receptor model, with the daily concentration of metals in the aerosol. The major primary sources of the aerosol of Beijing were considered to be soil dust and coal combustion. Vehicle exhaust contribution tended to increase.     

面向研究型的分析化学课程改革与实践

分析化学课程是化工专业最重要的基础课程之一,如何提高课程的授课效果受到众多教育工作者的重视。在对分析化学课程体系的改革和实践过程中,通过精炼授课内容,增大科研训练比率,可使学生深入浅出地、有重点地、系统地掌握分析化学的精髓。通过教学改革发现,学生利用业余时间和教学实习参加教师科研工作,能够较好的培养学生进行科学研究的能力。改革后有利于培养学生的综合素质和创新意识,并提高教学质量和教学效果。     

Critical assessment 29: TRIP-aided bainitic ferrite steels

Transformation-induced plasticity (TRIP)-aided bainitic ferrite steels developed for automotive applications have attractive mechanical properties such as ductility, formability, toughness, fatigue strength and delayed fracture strength. These mechanical properties are principally associated with a ductile lath-structure matrix and the strain-induced transformation of the metastable-retained austenite films of 3–20 vol.%. In this paper, data on the microstructural and mechanical properties of the low-carbon TRIP-aided bainitic ferrite steels are critically assessed, as well as their deformation mechanism.     

Additive-Free Enzymatic Phosphorylation and Ligation of Artificial Oligonucleotides with C-Nucleosides at the Reaction Points

We report enzymatic phosphorylation and additive-free ligation of DNAs containing unnatural C-nucleotide residues through the action of T4 polynucleotide kinase and T4 DNA ligase. The artificial units are each made up of an alkynyl deoxyribose component and one of the unnatural nucleobases D * , T * , G * , and C * , corresponding—from a viewpoint of hydrogen-bonding patterns—to natural A, T, G, and C, respectively. Phosphorylation progressed quantitatively at the 5′-end in the cases of all of the artificial units in the chimeric DNAs. Ligation also smoothly progressed at the 5′-end in the cases of the D* and G* nucleotide residues, but only negligibly in those of their T* and C* counterparts. Chemical redesign of the last two units successfully improved the ligation efficiency, so that enzymatic ligation worked well for all of the artificial units in every 3′-natural ⋅ 5′-artificial, 3′-artificial ⋅ 5′-natural, and 3′-artificial ⋅ 5′-artificial terminal combination at the nicks.     

Effects of Particle Strength of Feedstock Powders on Properties of Warm-Sprayed WC-Co Coatings

Warm spray (WS) process, which can control the temperature of a combustion gas jet used to propel powder, has been successfully applied to deposit WC-Co coatings. Detrimental reactions resulting from dissolution of WC into Co binder and decarburization were suppressed effectively by keeping the WC-Co particles’ temperature below the m.p. of the binder phase. In this study, three nano-structured WC-12Co powders with different particle strengths were prepared by changing the sintering conditions of spray-dried powder and were deposited by WS. The deposition efficiency and porosity of the coatings decreased with increasing the particle strength. The coating deposited from the powder with very low particle strength showed significant phase changes, while those deposited from the higher particle strengths showed almost no change. Particle Image Velocimetry revealed significant disintegration of the weakest powder, which explains the changes observed. The hardness and wear properties of the former coating, therefore, were inferior to the other two.     

流动城市

这是一个在商业公园、港口和机场之间开发的项目,要求不能违背大加那利群岛的地理特质。我们的目标是提高这些本地条件,注入明确的城市规划和景观规划方案。我们计划建立3个超级区域网络:东西向的地景河床     

Evaluation of cost reduction potential for 1 kW class SOFC stack production: Implications for SOFC technology scenario

Recently, a commercial version of a residential solid oxide fuel cell (SOFC) system with a flat tubular cell has been developed. However, the system cost still remains very high, which is a barrier to its widespread use. In this study, the potential for cost reductions in SOFC stack production was investigated in order to contribute to the viability of the widespread use of such residential SOFC systems in future. A cost analysis of 700 W SOFC stack production based on a process integration modeling was conducted. The present bottom–up approach enabled us to perform a sensitivity analysis with a variety of parameters in terms of cell design, the production process and cell performance. This allowed us to investigate the effects of these factors on the production cost, thereby revealing the quantitative impact of each technological improvement on the cost reduction potential. The present analysis also revealed innovation pathways which could result in technology scenarios where residential SOFC systems could reach a break-even point in comparison with the baseload electricity cost. The analysis of the cost reduction potential presented here provides a useful viewpoint for developing a research strategy for state-of-the-art SOFC technology.     

批判性地域主义视野下的少数民族民居建筑改造——以云南怒江流域干一它村傈僳族民居为例

在全球文化的“趋同”与地域文化符号化、表皮化的大背景下,以批判的地域主义为理论基础,重新审视该理论对我国少数民族直过区传统民居建筑的保护和传承的适应性发展。通过干一它村傈僳族传统民居建筑改造实践,提出回归本土居民的批判性思考,更多地关注民居建筑物理环境的舒适性、空间组织的地域适应性和地方依恋的地域载体,以弥补当下批判的地域主义实践在系统性考虑本土居民的需求上的缺失,探索传统民居建筑改造如何在传承中创新。     

低黏二氰胺类离子液体乙烯汽液相平衡研究

从工业废气中回收分离乙烯（C₂H₄）具有重要意义,选用了三种低黏度二氰胺类离子液体,分别测定了293.15~333.15 K下其密度、黏度等物化性质,研究了其对乙烯（C₂H₄）吸收性能。采用非随机（局部）双液体模型（NRTL）关联了三种二元体系溶解度数据,实验值与计算值的平均相对偏差均小于3%。结果表明,低黏度二氰胺类离子液体对C₂H₄气体吸收性能良好,其中阳离子侧链长度增加和羟基功能团引入可增强对C₂H₄溶解度。同时,离子液体1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）经过3次的吸收解吸循环,仍可以保持较好的C₂H₄吸收性能,表明该离子液体循环稳定性好,而1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）对乙烯吸收量较高,具有作为C₂H₄吸收剂的潜力。