快速溶解法在测定硅铁及其合金元素中的应用

建立快速溶解硅铁及其合金的试验方法,并利用电感耦合等离子体发射光谱仪分析检测硅铁及其合金中微量元素及痕量元素,证明了快速溶解法的可行性.结果显示,方法的精密度及检测仪器重复性测量不确定度的结果均符合国家标准规定的允许偏差范围,说明快速溶解法具有一定推广价值和应用前景.     

Erythemal Ultraviolet Exposure of Cyclists in Valencia,Spain

UV exposure is considered to be one of the most important risk factors in skin cancers, mainly in outdoor occupational or recreational activities. Outdoor athletes such as cyclists receive regular and significant solar UV erythemal radiation (UVER). The aim of this work was to quantify UVER exposure of amateur cyclists over the course of several days in their training schedules. To quantify UVER exposure of this group, dosimeters (Viospor) were attached at the top of the helmet in the course of their training. The study took place in Valencia, Spain, in June to July 2008 and February to March 2009, and involved a group of five cyclists over a period of 4 days for each period. The mean 2-day personal UV exposure was 32.24 ± 4.14 SED (standard erythema dose) in summer and 11.30 ± 5.36 SED in the winter period. One SED is defined as an effective radiant exposure of 100 J m⁻² when weighted with the International Commission on Illumination (CIE) erythemal response function. The mean exposure ratio (ER) of cyclists was 0.37 ± 0.04 in summer and 0.40 ± 0.11 in winter. The cyclists received the highest UVER exposure in the summer period, but in both training periods UVER exposure was in excess of occupational and recreational guidelines, indicating that protective measures are very necessary.     

塔克拉玛干沙漠黑碳气溶胶的特性及来源

长期监测并采集塔克拉玛干沙漠腹地的大气颗粒物及黑碳气溶胶样品.在塔克拉玛干沙漠腹地,沙尘气溶胶中的黑碳在PM10中的年平均含量高达1.14%,这说明在人迹罕至的塔克拉玛干沙漠地区,其上空的沙尘气溶胶也已经受到人为活动的影响.黑碳气溶胶具有明显的季节变化和日变化,冬季最高,平均达2261.7ngm-3,依次为冬季春季秋季夏季.黑碳气溶胶日变化特征与城市地区恰好相反,夜间高于白天,午夜0:00～2:00出现峰值,而在上午8:00～11:00出现低值.非沙尘暴期间黑碳对PM10的贡献是沙尘暴时期的11倍.塔里木盆地周边绿洲带人为活动,尤其是新疆南北部地区跨越春秋冬三季的居民采暖所产生的黑碳经由局地、区域或长途传输是塔克拉玛干沙漠腹地黑碳气溶胶的主要来源,也是沙漠黑碳气溶胶具有明显的季节特征和日变化的主要原因.随着沙尘气溶胶的长途传输,沙漠每年大约输出6.3×104吨黑碳气溶胶,这势必会对全球的气候与环境变化产生一定影响.     

离子交换法提取青霉素G的探索

研究了5种性能不同的树脂对青霉素G提取的影响,确定了非极性大孔吸附树脂为适合青霉素G吸附的树脂。同时采用正交实验设计研究了上柱青霉素G浓度,吸附流量,洗脱剂种类等因素的影响作用,从而确定了提取青霉素G的最佳条件:柱尺寸20×1cm,上柱青霉素G浓度90mg/ml5ml/min,洗脱剂1mol/L KCl。     

RADIOCHEMICAL INVESTIGATION OF MASS DISTRIBUTIONS IN 12C-INDUCED FISSION OF 209Bi AND 238U

The yields of 15 and 17 fission, products have been obtained by radiochemical determinations in ¹²C-induced fission of ²⁰⁹Bi and ²³⁸U respectively. From these data, the mass distributions of fission fragments are calculated based on three different hypotheses for the charge distribution. The results seem to indicate that the hypothesis of equal charge displacement gives the best fit to the Gaussian distribution for the masses of the fission fragments. By comparison with the mass distributions for ²⁰⁹Bi (¹²C, f), ²³⁸U(¹²C, f) and ¹⁹⁷Au(¹²C, f) in our early measurement, we find that for fission parameter Z²/A>37, the width of the mass distributions increases with Z²/A rapidly.     

Slow transition of energy transport in high-temperature plasmas

A new slow transition process for energy transport in magnetically confined plasmas is reported. The slow transition is characterized by the change between two metastable transport conditions characterized by a weak and a strong electron temperature (Te) dependence of normalized heat flux. These two branches are found to merge at the critical gradient. In metastable transport, the derivative of normalized heat flux to the Te gradient, [EQUATION: SEE TEXT], is positive, while it becomes negative during the transition phase. The time for the transition increases as the normalized Te gradient is increased and exceeds the transport time scale characterized by the global energy confinement time.     

Hydrothermal Synthesis and Characterization of [V_(16)O_(38)(Cl)][Cu(enMe)_2]_(3.5)·2H_2O Containing {V_(16)O_(38)} Cluster

IntroductionBasedonarelativelylargenumberofdifferenttypesofbuildingblockswhichcorrespondtopolyhe dron {VOx} (x =4 ,5 ,6 ) ,polyoxovanadatesshowanextraordinaryvarietyofstructures ,suchascage ,basket ,belt ,ballandbarrelstructures[1— 5] .Further more,these polyoxovanadatesexhibita pronouncedtendencytoformcage likestructureswhichmayen capsulateneutralmoleculesaswellasionicguests ,afeaturesharedbysomeisopolyanionssuchas [V18O4 2·(H2 O) ]12 - [6 ] ,[H4 V18O4 2 (X) ]9- (X =Cl- ,Br- ,I- ) [2 ,…     

Hydrothermal Synthesis and Structural Characterization of the Cage-based Arsenic-Vanadium Microporous Material: [As_2V~(IV)_8V~V_2O_(26)]·8H_2O

Interest in polyoxometalates is expanding rapidly due to the enormous variety of structure topologies leading to interesting and unexpected properties in such diverse field as catalysis, materials science and medicine1-4. Frameworks constructed from square pyramidal, octahedral, tetrahedral units are well documented in the solid-state phases of the V/O/P system5. For the heteropolyanions class of clusters, the V/O/As system has been extensively studied, but the linking of arsenic-vanadium …     

Occupational UV Exposure of Environmental Agents in Valencia,Spain

Excessive exposure to ultraviolet radiation (UVR) is considered the most important environmental risk factor in the development of melanoma and skin cancer. Outdoor workers are among those with the highest risk from exposure to solar UVR, as their daily activities constantly expose them to this radiation source. A study was carried out in Valencia, Spain, in summer 2012 and involved a group of 11 workers for a period of six 2‐day recordings. Sensitive spore‐film filter‐type personal dosimeters (VioSpor) were used to measure erythemal UVR received by environmental agents in the course of their daily work. Median 2‐day UV exposure was 6.2 standard erythema dose (SED), with 1 SED defined as effective 100 J m^?2 when weighted with the Commission Internationale de L′Eclairage's (CIE) erythemal response function. These workers were found to receive a median of 8.3% total daily ambient ultraviolet erythemal radiation. Comparison with the occupational UV exposure limit showed that the subjects had received an erythemal UV dose in excess of occupational guidelines, indicating that protective measures against this risk are highly advisable.