Trace elements in particles of motor vehicle exhaust in Shanghai

A nuclear microprobe with high spatial resolution and high analytical sensitivity was applied to analyze trace elements,especially lead,in vehicle exhaust of Shanghai city.The result shows that the chemical composition and its corresponding x-ray relative intensity are different among different vehicle exhausts.There are many kinds of metal elements in particles of vehicle exhaust.most are harmful to people,such as Ti,Cr,Mn,Pb,etc.We found that the lead concentration was 6820μg/g and the bromine concentration was 5300μg/g in the exhaust from Santana using leaded gasoline(SULG).which is higher than any other kinds of vehicle exhausts.We have also detected the minimum lead in the particles of unleaded gasoline and its content varies from one to another.Its mean concentration was 450μg/g and the highest reached 6210μg/g.The unleaded gasoline‘s Pb existed in the whole particle while the leaded gasoline‘s enriched in the surface of the particle and was more harmful to the human beings.     

基于环形对称Gabor变换和PCA加权的人脸识别算法

环形对称Gabor变换不但具有Gabor小波的一般特性,而且具有信息冗余度小、严格的旋转不变性等优点.文中提出一种基于环形对称Gabor变换和PCA加权特征的人脸识别算法.首先将人脸图像变换到环形对称Gabor变换域,然后在变换域采用PCA加权方法提取分类特征.在3个人脸库上进行实验,与传统人脸识别算法的对比实验说明该算法的可行性和对光照、姿态变化具有更好的鲁棒性.     

Chemical compositions and some physical properties of the water and alkali-extracted mucilage from the young fronds of Asplenium australasicum (J. Sm.) Hook

Effect of extraction conditions, including solvent types (water and sodium bicarbonate) and extraction temperatures (25, 50, 70 and 90 °C), on the physicochemical properties of the water and alkali-extracted mucilage from the young fronds of Asplenium australasicum (J. Sm.) Hook was evaluated. It was found that sodium bicarbonate extract generally showed higher yield than water extract, and its yield increased with increasing extraction temperature. Composition analysis revealed that A. australasicum mucilage was composed of mainly carbohydrates in conjunction with some glycoproteins. The weight average molecular size of the carbohydrate fraction of crude mucilage obtained from alkali and water extractions were about 6.30 × 10⁷ and 2.63 × 10⁷, respectively. Sugar composition analysis revealed that A. australasicum young fronds mucilage contained significant amount of uronic acid (14.3-56.6% based on total sugars). For the water extracted mucilage, GlcA is predominant. However, for the sodium bicarbonate extracted mucilage, GalA is predominant. Furthermore, Rha can only be detected in sodium bicarbonate extract. Other major neutral sugars include Gal, Man, Xyl and Fuc. The intrinsic viscosity of the water and alkali-extracted mucilage in deionized water were around 21.12 and 5.92 dL/g, respectively. This information would be useful when considering A. australasicum young fronds mucilage as a new Agro-ingredient.     

Phenolic tyrosinase inhibitors from the stems of Cudrania cochinchinensis

The phytochemcal profiles of Cudrania cochinchinensis leaf, twig, stem and root were compared by HPLC analysis. It was found that C. cochinchinensis stem extract contained some unknown natural products with potential tyrosinase inhibitory activities. Therefore, the chemical constitutes in extract (95% ethanol) of C. cochinchinensis stem were further investigated in this study. A new racemic mixture, (±)2,3-cis-dihydromorin, and fifteen known phenolic compounds, dihydrokaempferol 7-O-β-d-qlucopyranoside, skimmin, quercetin-7-O-β-d-glucoside, 2,3-dihydroquercetin 7-O-β-d-glucoside, kaempferol-7-O-β-glucopyranoside, quercetin-3,7-di-O-β-d-glucoside, morin-7-O-β-d-glucoside, 1,3,5,8-tetrahydroxyxanthen-9-one, 2,3-trans-dihydromorin, aromadendrin, oxyresveratrol, genistin, protocatechuic acid, kaempferol 3,7-di-O-β-glucopyranoside, and naringenin were isolated. Spectral techniques (MS, (1)H NMR and (13)C NMR) were utilized for their structural identification and their inhibitory activities on mushroom tyrosinase were also evaluated. The results showed that tyrosinase inhibitory activities of (±)2,3-cis-dihydromorin (IC(50) = 31.1 μM), 2,3-trans-dihydromorin (IC(50) = 21.1 μM), and oxyresveratrol (IC(50) = 2.33 μM), were more potent than that of kojic acid (IC(50) = 50.8 μM), a well-known tyrosinase inhibitor, indicating that Cudrania cochinchinensis stem will be a great potential agent for the development of effective natural tyrosinase inhibitors.     

Lattice Parameter and Stoichiometry of TiCx Produced in the Ti–C and Ni–Ti–C Systems by Self-Propagating High-Temperature Synthesis

The lattice parameter and stoichiometry of TiC _x produced in the Ti–C and Ni–Ti–C systems with a range of C/Ti ratios were investigated, respectively. Compared with the Ti–C system, the addition of Ni can not only increase the lattice parameters and stoichiometry of TiC _x by forming Ni–Ti compounds (for C/Ti ≤0.8) but also decrease them (for C/Ti >0.8) due to the hindering of atom diffusion caused by the dilution of Ni and the decreasing combustion temperature. For all complete reaction in the Ti–C and Ni–Ti–C systems, the combustion temperature plays a crucial role in the determination of the lattice parameters and stoichiometry of TiC _x .     

Balancing the strength and ductility of Mg-6Zn-0.2Ca alloy via sub-rapid solidification combined with hard-plate rolling

In this study,we successfully prepared a Mg-6Zn-0.2Ca alloy by utilizing sub-rapid solidification (SRS)combined with hard-plate rolling (HPR),whose elongation-to-failure increases from ～17 ％ to ～23 ％without sacrificing tensile strength (～290 MPa) compared with its counterpart processed via conven-tional solidification (CS) followed by HPR.Notably,both samples feature a similar refined grain structure with an average grain size of ～2.1 and ～2.5 μm,respectively.However,the high cooling rate of ～ 150 K/s introduced by SRS modified both the size and morphology of Ca2Mg6Zn3 eutectic phase in comparison to those coarse ones under CS condition.By subsequent HPR,the Ca2Mg6Zn3 phase was further refined and dispersed uniformly by severe fragmentation.Specially,the achieved supersaturation containing exces-sive Ca solute atoms due to high cooling rate was maintained in the SRS-HPR condition.The mechanisms that govern the high ductility of the SRS-HPR sample could be ascribed to following reasons.First,refined Ca2Mg6Zn3 eutectic phase could effectively alleviate or avoid the crack initiation.Furthermore,excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability during tension.The findings proposed a short-processed strategy towards superior performance of Mg-6Zn-0.2Ca alloy for industrial applications.     

复杂异构计算系统HPL优化研究

当今世界的主流超级计算机越来越多地使用带有加速器的异构系统.随着加速器的浮点性能不断提高,超级计算机内计算节点的CPU、内存、总线、网络以及系统架构都要与之相适应.HPL（High Performance Linpack）是高性能计算机评测的传统基准测试程序,复杂异构系统给HPL评测带来很多机遇与挑战.针对带有GPU的异构超级计算机系统,提出一套新的CPU与加速器计算任务分配方式,提出平衡点理论指导HPL性能优化.为了优化HPL程序,提出了使用CPU与加速器协同工作的look-ahead算法和行交换连续流水算法,实现了加速器、CPU、网络等部件的高度并行.此外,为带有加速器的系统设计了新的panel分解和行交换的实现方法,提高加速器的利用率.在每个节点带有4个GPU的系统上,单节点HPL效率达到79.51%,14884节点效率达到62.22%.     

三磷酸肌醇清除自由基的作用

采用电子自旋共振波谱仪检测了三磷酸肌醇（IP3）清除羟基自由基（·OH）和超氧阴离子自由基（O）的作用。结果表明：利用Fenton反应体系,酵母和植酸酶制备的IP3对基自由基（·OH）的清除率各达75．34％和73．29％,样品浓度分别为6mg／ml和9mg／ml;利用次黄嘌呤-黄嘌呤氧化酶体系,酵母和植酸酶制备的IP3对超氧阴离子自由基（O）的清除率达72．76％和53．84％,样品浓度分别为18mg／ml和9mg／ml。同时认为IP3之所以对多种疾病具有预防、减轻和治疗效果,主要是因为IP3具有比较强大的清除自由基的功能。     

8种食用植物油碳原子当量42和44甘油 三酸酯含量的测定

目的 了解碳原子当量在食用植物油掺伪中的应用价值。方法 采用气相色谱法和高效液相色谱法分别对8种常见食用植物油的碳原子当量42(ECN42)和44(ECN44)甘油三酸酯含量进行了计算和比较。结果 花生油与菜籽油各指标较接近, 大豆油、玉米油和葵花籽油各指标较接近, 而高品质的橄榄油与山茶油各指标较接近。但橄榄油和山茶油的ECN42和ECN44值远低于高亚油酸的大豆油、玉米油等种籽油类, 且差异具有显著性(P<0.05); 而山茶油与橄榄油之间, 只有实际和理论甘油三酸酯含量最大差值(ΔECN42、ΔECN44)有显著性差异(P<0.001)。结论 本文首次对国内市场中常见食用植物油的ECN42和ECN44甘油三酸酯含量进行检测和总结, 此结果为进一步开展食用植物油掺伪鉴别研究奠定了基础。     

Source apportionment of single aerosol particles in the atmosphere of Shanghai city

A nuclear microprobe with high spatial resolution and high analytical sensitivity was applied to analyze atmospheric aerosol at five monitoring sites in Shanghai city.Meantime,a new pattern recognition technique,which used the micro-PIXE spectrum of a single aerosol particle as its fingerprint.was developed to identify the origin of the particle.The results showed that the major contributors to the atmosphere pollution were soil dust(31.6%) ,building dust(30.8%),and the next were vehicle exhaust(13.7%),metallurgic industry excrements(5.6%).oil combustion(5%) and coal combustion(2.3%).Besides these ,about 10% of the particles could not be identified.Based on the cluster analysis of these particles.they could be divided into eight groups.By inference,they might belong to some sub-pollution sources from soil dust,building dust and metallurgic industry excrements.Moreover,some new pollution sources from tyres and chemical plants were also revealed.