Quo Vadis total reflection X-ray fluorescence?

The multielement trace analytical method ‘total reflection X-ray fluorescence’ (TXRF) has become a successfully established method in the semiconductor industry, particularly, in the ultra trace element analysis of silicon wafer surfaces. TXRF applications can fulfill general industrial requirements on daily routine of monitoring wafer cleanliness up to 300 mm diameter under cleanroom conditions. Nowadays, TXRF and hyphenated TXRF methods such as ‘vapor phase decomposition (VPD)-TXRF’, i.e. TXRF with a preceding surface and acid digestion and preconcentration procedure, are automated routine techniques (‘wafer surface preparation system’, WSPS). A linear range from 10⁸ to 10¹⁴ [atoms/cm²] for some elements is regularly controlled. Instrument uptime is higher than 90%. The method is not tedious and can automatically be operated for 24 h/7 days. Elements such as S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sn, Sb, Ba and Pb are included in the software for standard peak search. The detection limits of recovered elements are between 1×10¹¹ and 1×10⁷ [atoms/cm²] depending upon X-ray excitation energy and the element of interest. For the determination of low Z elements, i.e. Na, Al and Mg, TXRF has also been extended but its implementation for routine analysis needs further research. At present, VPD-TXRF determination of light elements is viable in a range of 10⁹ [atoms/cm²]. Novel detectors such as silicon drift detectors (SDD) with an active area of 5 mm², 10 mm² or 20 mm², respectively, and multi-array detectors forming up to 70 mm² are commercially available. The first SDD with 100 mm² (!) area and integrated backside FET is working under laboratory conditions. Applications of and comparison with ICP-MS, HR-ICP-MS and SR-TXRF, an extension of TXRF capabilities with an extremely powerful energy source, are also reported.     

新世纪的数字网络电视

本文介绍了新世纪有线、无线电视台在制作、传输、管理方面的数字化、网络化、智能化的一些方针、策略，并且对电视台的采、编、录、播一体化的信息综合管理进行了探讨。     

生地当归药队煎剂的表面增强拉曼散射光谱

为揭示单味煎剂与方剂间的关系,分别测试分析了生地当归药队、单味药生地和单味药当归煎剂的表面增强拉曼散射(surface-enhanced Raman scattering, SERS)光谱,并对其进行谱峰归属。本文主要针对存在于三种煎剂中的17个拉曼信号(538,622,732,761,835,876,959,1 145,1 245,1 276,1 326,1 402, 1 456,1 470,1 518,1 546和1 605 cm-1)进行讨论。生地当归药队煎剂SERS光谱在538,732,761,835,876,959,1 145,1 245,1 276,1 326,1 402,1 456,1 470,1 518和1 605 cm-1处,出现15个明显的拉曼信号;生地煎剂SERS光谱在538,761,835,876,959,1 145,1 245,1 276,1 326,1 402,1 470,1 518和1 546 cm-1处,出现13个明显的拉曼信号;当归煎剂SERS光谱在538,622,732,761,835,876,959,1 245,1 326和1 402 cm-1处,出现10个明显的拉曼信号。生地当归药队煎剂SERS光谱保留了和未观察到生地和当归单味煎剂的某些拉曼峰,且产生了生地和当归单味煎剂中所没有的拉曼信号(1 456和1 605 cm-1),即产生新药物成分。生地当归药队煎剂所包含的药物成分并非是生地和当归单味药物煎剂所含药物成分的简单相加。结果表明,SERS光谱可能为方剂研究提供一种高灵敏度、快速准确和操作简单的检测方法。     

Application of generalized diagonal dominance in wireless sensor network optimization problems

The recent application of the diagonal dominance in the development of the optimization algorithms in the wireless sensor networks design, has been done by Yuan and Yu (2006) [14], extended in Yu et al. (2006) [9], and surveyed in Machado and Tekinay [11]. In this paper, we will use the concept of generalized diagonal dominance, to improve the obtained results regarding the power control game, in three directions. We also discuss the applicability of such improvements.     

Low-energy EDX – A novel approach to study stress corrosion cracking in SUS304 stainless steel via scanning electron microscopy

Intergranular stress corrosion cracking (IGSCC) in type SUS304 stainless steels, tested under pressurized water reactor (PWR) primary water conditions, has been characterized with unprecedented spatial resolution using scanning electron microscopy (SEM) and novel low-energy (∼3 kV) energy dispersive X-ray spectroscopy (EDX). An advancement of the large area silicon drift detector (SDD) has enhanced its sensitivity for X-rays in the low-energy part of the atomic spectrum. Therefore, it was possible to operate the SEM at lower accelerating voltages in order to reduce the interaction volume of the beam with the material and achieve higher spatial resolution and better signal-to-noise ratio. In addition to studying the oxide chemistry at the surface of intergranular stress corrosion cracks, the technique has proven capable of resolving Ni enrichment ahead of some crack tips. Active cracks could be distinguished from inactive ones due to the presence of oxides in the open crack and Ni-rich regions ahead of the crack tip. Furthermore, it has been established that SCC features can be better resolved with low-energy (3 kV) than high-energy (12 kV) EDX. The low effort in sample preparation, execution and data analysis makes SEM the ideal tool for initial characterization and selection of the most important SCC features such as dominant cracks and interesting crack tips, later to be studied by transmission electron microscopy (TEM) and atom probe tomography (APT).     

Synthesis,enzymes inhibitory properties and characterization of 2- (bis (4-aminophenyl) methyl) butan-1-ol compound: Quantum simulations,and in-silico molecular docking studies

In this study to be presented, the BAPMB molecule was synthesized and structurally characterized. All calculations were applied using the detailed DFT/B3LYP method with 6-311G (d, p) and SDD depended on the stable phase geometry of the molecule. Also, various HOMO-LUMO energy gaps, inter-orbital intramolecular interactions of the natural bond, and electro-static surface mapping actions were also realized. The molecule was characterized by NMR spectroscopic analysis. Besides, LC/MS data were acquired. In this analysis, fragment ions (m/z 168.9) of BAPMB were obtained as 137.8, 179.9, 198, 201.5, and 228.0 approximately. Also, molecular docking was performed while examining the exact binding site and binding mechanism of the ligand on the protein. In the study, glide scores in binding affinity with BAPMB – AChE, BAPMB – BChE, and BAPMB – GST, respectively; It was found to be −7.228 ​cal/mol, −7.205 ​cal/mol, −6.07 ​cal/mol and BAPMB - AChE was found to be more effective with receptor binding score. BAPMB was analyzed for its inhibition features counter AChE, BChE, and GST enzymes that exhibit effective inhibition. AChE, BChE, GST enzymes were powerfully inhibited by BAPMB. BChE showed excellent activity, particularly in comparison to standard tacrine. Eventually, AIM analysis was performed to search intermolecular interactions in the BAPMB compound.     

MIMO通信系统中QAM信号的快速半盲均衡算法研究

该文针对传输正交幅度调制(QAM)信号的多输入多输出(MIMO)系统的均衡问题,结合方环算法(SCA)的简单性和软决策(SDD)算法的精确性,提出了一种既比较精确又简单的算法(SCA+SDD)。在优化该算法的代价函数过程中,首先用很少的训练序列(等于接收天线数)得到均衡器权向量的一个粗略估计,然后提出利用共轭梯度法进行迭代优化该代价函数的方法,该算法具有近似的二次收敛性,与传统梯度类算法相比较,该方法有非常快的收敛速度和较少的计算量。最后通过误码率(BER)和收敛速度分析该算法的可靠性和有效性,并且通过计算机仿真证明了该算法的良好性能。     

一种改进了碰撞电离的超高速InP基SHBT SDD模型

从物理机制上分析了超高速InP/InGaAs SHBT碰撞电离与温度的关系,通过加入表示温度的参数和简化电场计算,得到一种改进的碰撞电离模型.同时针对自有工艺和器件特性,采用SDD(symbolically defined device)技术建立了一个包括碰撞电离和自热效应的InP/InGaAs SHBT的直流模型.模型内嵌入HP-ADS中仿真并与测试结果进行比较,准确地拟合了InP/InGaAs SHBT的器件特性.     

基于SDD的太阳X射线探测器脉冲成形电路设计

设计应用在风云二号03批空间环境探测器上的太阳X射线探测器在研制过程中需要一套完善的地面测控系统,太阳X射线探测器采用性能优越的SDD(Silicon Drift Detector,硅漂移传感器),主要对地面测控系统的脉冲成形电路进行了详细的电路分析,改进了电路结构,采用高速运算放大器实现了脉冲信号的滤波成形,用较少级数进行滤波即得到准高斯波形。利用Multisim12.0软件对成形电路的不同参数进行仿真测试,实验结果表明,设计电路达到了设计指标要求,具有移植性和通用性,使其能够在后端的脉冲幅度分析电路中被有效利用。     

Evolution of Electron Velocity Distribution during ECRH and Heating Effect Analysis

1 Electron velocity distributions and energy deposition of ECW Two set of soft X-ray spectra detection system consist of high performance sillicon drift detectors （SDD） , high speed A/D transform and processing software, software pulse height analyzer （SPHA）. They are installed at mid plane （ r=0 ） and undermid plane （ r=-16.4 cm ） of HL-2A tokamak respectively to measure the time evolution of soft X-ray spectra. According to spectrum, the thermal electron and superthermal electron temperatures are derived. Because of the ratio of peak counts to background counts is very high （p/b 〉1 400-3000 ） ,