Capillary injection device for in situ pre-concentration of trace elements in graphite furnace-atomic absorption spectrometry

A device for in situ pre-concentration of trace elements in graphite furnace-atomic absorption spectrometry (GF-AAS), which is based on the direct introduction of the sample solution into the furnace by a fused silica capillary, is described. Experimental conditions have been optimized for the determination of several elements at the sub pg/g level with a CV always better than 15%. A deposition yield of approximately 95% was estimated by depositing a solution containing NaCl 0.002 M. A very simple and effective device for handling a sample under contamination-free conditions is also described which allowed a CV less than 10% to be obtained for replicate determinations of Cd in blank samples at 0.4 pg/g. The overall analytical system was validated by recovery studies carried out on standard solutions and spiked snow samples. Measurements were performed at 1, 5 and 50 pg/g, and the error was always lower than 20, 10 and 5%, respectively. The evaluation of the experimental detection limits which ranged in the interval 0.1–4 pg/g is finally discussed.     

不同电子传输层的蓝光有机电致发光器件的性能研究

自从Tang等^[1]首次报道多层有机电致发光器件（OLED）以来,其在亮度和效率上有了质的飞跃,表明器件的结构对提高发光亮度和发光效率起着至关重要的作用,单层器件虽然具有制作简单的优点,但却存在明显缺点：（1）复合发光区靠近金属电极,该处缺陷很多,非辐射复合几率大,导致器件效率降低;（2）由于两种载流子注入不平衡,载流子的复合几率较低,因而影响器件的发光效率,要使发光层中具有高的载流子辐射复合效率,两种载流子的注入及传输能力应相当,否则传输快的一方就会直接穿过发光层到达对电极被猝灭,平衡电子和空穴的注入与传输可通过在电极和发光层之间加入载流子输运层或限制层制作多层器件的途径来实现,基于上述考虑,我们以PPCP为发光层（PPCP是一种荧光效率较高的蓝光材料^[2-4],对其进行深入研究尚未见有文献报道＿,设计了4种不同电子传输层（ETL)的三层 结构的OLED,为研究电子传输层对器件性能的影响,我们还制备了不含电子传输层的双层器件,结果表明,通过选择合适的ETL,OLED的发光亮度及发光效率会有很大程度的改善。     

标准负阶跃力的实现及其测量研究

本文介绍了新研制成功的用于对大力值（最大1200KN）、宽频带（最高分析频率50kHz)的力传感器动态特性校准的标准负阶跃力装置,该装置是基于帕斯卡原理和冲击卸荷方法来实现的,文中详细介绍了力传感器输出电压和用激光测速仪测量负阶跃力跃变过程的高速数据同步采集技术。     

准球面冲击波高压回收装置的研究

研究了以硝基甲烷液体炸药作为冲击波发生源的准球面汇聚冲击波超高压回收装置。在该装置上 ,利用冲击波由金属球体表面向中心汇聚形成的高压 ,对样品进行了冲击处理 ;分析了回收的金属球体内、外破坏情况及金相组织变化。结果表明 :该装置产生的球面冲击波对称性较好 ,样品回收可靠性较高 ;金属球体中心附近压力超过 2 0 7GPa ;对进行超高压冲击条件下的材料回收实验有较高的实用价值。     

卷积Turbo码编码器及CPLD实现

详细探讨了卷积Turbo码编码器实现过程中的关键问题,结合CCSDS及IMT－2000国际通信标准给出了具体解决方案,使用Maxplus2开发工具在CPLD上实现整个卷积Turbo码编码器并给出了系统分析,实验结果表明了该编码器的正确性和合理性。     

An Accurate Characterization of CRT Monitor (II) Proposal for an Extension to CIE Method and Its Verification

According to the ICC specification that is widely used for storing colorimetric characteristics of imaging devices for the current color management systems (CMSs), CRT monitor characteristics can be described by the tone reproduction curves (TRCs) of the red, green and blue channels and a transformation matrix from linearized RGB values to tristimulus values. This idea is based on CIE Technical Report 122#x2013;1996: #x201C;The Relationship between Digital and Colorimetric Data for Computer-Controlled CRT Displays,#x201D; which resulted from the research by Berns et al. This method produces very accurate results under normal conditions. However, users often change the settings of contrast or brightness knobs to a different position from the factory default adjustments. For some of these cases, the characterization method described in the CIE 122 does not produce accurate results. In this paper, we propose an extension to the CIE method for such cases. We investigated the effect of user controls on CRT monitor characteristics at various settings, and verified that our method produced accurate results under any conditions.     

A Novel Greenish Blue‐emitting Amorphous Molecular Material: 2,5‐Bis {4‐[2‐naphthyl (phenyl) amino ] phenyl} thiophene

A novel greenish blue‐emitting amorphous molecular material, 2,5‐bis{4‐[2‐naphthyl(phenyl)amino]phenyl thiophene (BN‐pA‐1T), was designed and synthesized. Its molecular properties, glass‐forming property, and application to an organic EL device were investigated.     

Zig-Zag Type Molecular Design Strategy of N-Type Hosts for Sky-Blue Thermally-Activated Delayed Fluorescence Organic Light-Emitting Diodes

N-type hosts for long lifetime in sky-blue thermally-activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) were investigated by synthesizing four hosts with zig-zag-type backbone structure for high triplet energy. The four hosts had two CN units at different positions of the zig-zag-type backbone structure and two dibenzofuran units through either the 2 or 4-position of dibenzofuran. The position of the CN unit was controlled at the meta and para-positions in the zig-zag-type backbone to study the relationship between material parameters and lifetime of the TADF OLEDs. It was revealed that the meta-orientation of the CN units in the backbone was advantageous to extend device lifetime of the sky-blue TADF OLEDs.     

Dilution Device for Coupling Monitors to Source Emissions

Abstract

The coupling of continuous gaseous source monitors to stacks or ducts usually requires some degree of sample conditioning. A novel device has been designed and constructed to eliminate the problems of moisture condensation and particulate entrainment in sampling systems by diluting the stack gas in-situ and measuring the resulting sample stream with ambient air sensors. Dilution ratios of from 500:1 through 2400:1 have been studied and the feasibility of a prototype design has been demonstrated in the field.