高温石墨炉法测定痕量金属的条件选择

高温石墨炉法测定痕量金属对工作条件的要求非常严格,影响分析准确度和精密度的原因较多。从干燥温度和时间,灰化温度和时间,原子化温度和时间,高温除残温度和时间的选择,自动进样器的调整,试样处理等几个方面,合理、正确地选择工作条件能够得到最佳吸收灵敏度和测量精密度。     

石油烃中微量含氧化合物的检测

根据Deans Switch中心切割原理,建立了一种采用微板流路控制的毛细管气相色谱切割反吹技术分析石油烃中微量含氧化合物的方法。以非极性DB-1石英毛细管色谱柱(简称DB-1柱)为预分析柱、强极性CP-Lowox石英毛细管色谱柱(简称CP-Lowox柱)为分析柱,通过设置电磁阀的切换时间可将DB-1柱中需检测的含氧化合物组分切割至CP-Lowox柱进一步分离,Deans Switch切割时带入的烃在CP-Lowox柱上与含氧化合物的分离效果良好,不干扰石油烃中含氧化合物的检测。采用外标法定量,通过标准试样线性效果验证,各含氧化合物的标准工作曲线的相关系数均达到0.99以上,相对标准偏差为0.73%~1.05%,回收率为89.68%~101.40%,具有良好的精密度和准确度。通过对实际试样进行测定,定量结果准确。     

裂解气相色谱-质谱法鉴别双组分丙烯酸汽车清漆

为了提高微量物证鉴定中对双组分丙烯酸汽车清漆的鉴别能力，采用裂解气相色谱-质谱法(Py-GC/MS)检测该类清漆，并考察该方法在鉴定实践中的适用性。该方法的重现性好，丙烯酸聚氨酯清漆3个裂解单体的相对峰面积的日内RSD不大于5.3%，日间RSD不大于10.6%。应用该方法对6种丙烯酸氨基树脂汽车清漆样品及一例微量物证案件送检样品进行检测，结果表明，裂解气相色谱-质谱法对双组分丙烯酸汽车清漆的鉴别能力优于红外光谱法。在微量物证鉴定实践中，需要根据检材量酌情使用此方法，并注意“先无损后有损”的检验顺序。     

一种基于通讯痕迹的社会网络团伙分析模型

研究在已知目标团伙中某节点以及目标团伙特征的前提下,基于通讯痕迹特征寻找社会网络团伙。研究过程中引入了社会圈、节点中心度和事件集合关联矩阵等概念,重点将聚类分析方法与社会团伙发现相结合,以期得到一种基于通讯痕迹的社会网络团伙分析模型。     

Consuming,sharing, and creating content: How young students use new social media in and outside school

This survey study investigated 186 secondary 2–5 school students from two schools to understand how and why they used new social media both in and outside of school to consume, share, and create content. It found that whereas students tend to consume and share more social media content outside of school they create more in school. Perceived importance of sharing content with peers or others is the most significant predictor having positive impact on all social media activities, both in and outside school. However, the negative impact of self-regulation ability on outside school social media activities implies the conscientiousness of their social media engagement, which calls for a further investigation on the quality of the social media content.     

Geochemical characteristics of major and trace elements in Sahinali Coals,Aydin, Turkey

In this study, geochemical behavior of elements is investigated in 25 coal samples collected at 10 locations of ?ahinli coaliferous units at southeast of Ayd?n, Turkey. In all the samples, X-ray powder diffraction and inductively coupled plasma mass spectrometry analyses were performed and element and mineral compositions were determined. Total organic carbon (TOC) values of coals are between 14.6 and 37.7 wt% with average of 28.5 wt%. Samples are composed of quartz, calcite, feldspar, dolomite, mica, gypsum, and salt minerals which are accompanied by illite-, kaolinite-, and smectite-type clay minerals. Comparison of average element contents of world coals and studied samples yields that K > Fe > As > U > Cs > Y > Er > Al > Th > Rb > Yb > W > Tb > Dy > Lu > Ce > Sm > La > Ho > Si > Nd > Gd > Tm > Eu > Nb > Pr > Pb > Sn > Ni > Cu > Ga > Ta > Sb > Zr > Cd > V > Zn > Co > Mo > P > Hf > Ba are found to be enriched, while Mn > Be > Ca > Sr > Bi > Mg are found to be depleted. Statistically elements are correlated with TOC.     

Adsorption Equilibrium Parameters of Trace Impurities

Abstract

Atmospheric air contains various trace impurities which include oxides of nitrogen, carbon, sulphur, and light hydrocarbons. Prior to cryogenic distillation of air to produce oxygen, nitrogen, and argon, these trace impurities have to be removed since many of these compounds constitute a safety hazard in the plant. In this study, adsorption has been considered for their removal and adsorption behavior of ethylene, acetylene, nitrous oxide, acetonitrile, methyl tert-butyl ether, methyl sulfoxide, dimethyl sulfoxide, and methanol have been studied in the Henry's Law low concentration region with several different adsorbents. Adsorption equilibrium parameters have been determined with samples of Alcan pure alumina, Alcan alumina/13X composites Actiguard 600/650PC, CABSORB Chabazite, Ceca13X, and Clinoptilolite by using the concentration pulse chromatographic technique. Heat of adsorption values and van't Hoff plots have been presented.     

Determination of toxic and essential elements in sunflower honey from Thrace Region,Turkey

The aim of this study was to determine the levels of copper (Cu), manganese (Mn), zinc (Zn), iron (Fe), cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni) and selenium (Se) in sunflower honeys obtained from Thrace Region of Turkey. Trace and toxic element determination was performed by atomic absorption spectrometry after microwave digestion. The accuracy of the method was checked by the standard reference material, NIST‐SRM 1515 Apple leaves. The maximum contents of trace and toxic elements in honey samples from Kesan (polluted area) were found as 0.46, 0.82, 1.98, 14.0, 9.86 μg kg^?1, 0.48 mg kg^?1, 137, 115 and 290 μg kg^?1 for Cu, Mn, Zn, Fe, Cd, Pb, Cr, Ni and Se, respectively.     

“物理光学”研究型教学模式探索与实践

针对专业课的特点和教学要求,本文研究探索如何将研究型教学理念贯穿于"物理光学"教学过程中,通过对研究型教学内涵的分析,介绍了教学改革的具体措施与实施过程。实践表明,研究型教学理念的应用有助于调动学生的积极性,培养学生的创新能力和团队意识,取得很好的教学效果。