355 nm DPSS UV laser cutting of FR4 and BT/epoxy-based PCB substrates

The 355 nm DPSS UV laser cutting of electronics printed circuit board (PCB) substrates including FR4, and BT/epoxy-based PCB substrates was investigated. The effects of various laser conditions such as scanning speed, assisting gas, repetition rate, and interval between scans on the heat affected zone (HAZ) and charring were studied. The quality and morphology of laser cut PCB substrates were evaluated with optical microscope, and scanning electron microscope (SEM). It was found that multi-pass cutting at high scanning speed can achieve high quality cutting with little charring. It was also found that with O₂ assist gas, a certain amount of interval time between scans and higher repetition rate led to less HAZ and less charring. High quality laser cutting of PCB substrates with no delamination, very little charring and minimum HAZ was demonstrated. The developed process has important potential applications in the electronics industry.     

利用CP-150萃取回收PCB碱性蚀刻废液中的铜

利用CP-150萃取剂萃取碱性蚀刻废液中的铜,并利用硫酸进行反萃取。考察不同因素对萃取和反萃取的影响。萃取实验表明,铜的萃取率随着萃取剂浓度和相比增大而增大,随着料液铜浓度的升高而降低。反萃实验表明,反萃速率随着硫酸反萃液浓度的增大而增大。     

基于Linux的进程调度研究

通过对Linux进程调度函数源码的分析,深入剖析了kernel核进程调度流程、调度时机、进程PCB和进程调度的依据．针对进程调度中出现的优先级反向问题,给出了基本优先级继承协议和优先级上限继承协议两种解决方法。     

功率变流器EMI建模和印刷电路板(PCB)布置的优化设计

提出了无源元件和印刷电路板(PCB)布线寄生参数提取的方法;继而从器件机理出发,提出了PIN二极管和功率MOSFET的EMI高频模型和新的模型参数的提取方法;在此基础上,提出了建立功率变流器精确传导EMI时域模型的方法和步骤;探索了功率变流器PCB板布置的优化设计,可用于指导电力电子产品开发初期的EMC设计。     

Analysis of Affinity Energy Between Biphenyl Dioxygenase and Polychlorinated Biphenyls Using Molecular Docking

Molecular docking was used to calculate the affinity energy between biphenyl dioxygenases(BphA),including 1ULJ,1WQL,2YFJ,2YFL,2GBX,2XSH,2B4P,3GZX,and 3GZY(selected from the Protein Data Bank)and 209 polychlorinated biphenyl(PCB)congeners.The relationships between the calculated affinity energy and the persistent organic pollutant characteristics(migration,octanol-air partition coefficients,lgKOA;persistence,half-life,lgt1/2;toxicity,half-maximal inhibitory concentration,IgIC50;bioaccumulation,bioconcentration factor,lgBCF)of the PCBs were studied to mderstand the BphA mediated degradation of PCBs.The effect of substituent characteristics on the affinity energy was explored through full factorial experimental design.The affinities of nine kinds of BphA proteins on PCBs ranked as follows:2GBX>2YFJ>2YFL>3GZX>2XSH>3GZY>2E4P>1 WQL>1ULJ.The relationships between the calculated affinity energy and the molecular weight,lgKOA,lgBCF,and lgt1/2 of the PCBs were statistically signiflcant(p<0.01),whereas the relationship with the lgIC50 of PCBs was not statistically significant(p>0.05).PCBs were more difficult to degrade following an increase in the free energy of binding.Correlation analysis showed that the average affinity energy values of PCBs gradually increased as the number of chlorine atoms increased,regardless of the substituent position.The substituents at the ortho-positions interacted mainly through a second-order interaction,whereas those at the para-positions did not participate via a second-order interaction.     

基于自组装电化学免疫传感器对污泥中PCB77的检测

构建了一种基于L-半胱氨酸、 壳聚糖、 戊二醛和纳米金层层自组装技术的新型无标记、 高灵敏电流型免疫传感器, 并用于检测3,3',4,4'-四氯联苯(PCB77). 利用示差脉冲法研究了修饰电极表面的电化学特性以及测试溶液的pH值、 孵育时间和温度对免疫传感器性能的影响. 实验结果表明, 该免疫传感器在含不同浓度PCB77的磷酸盐缓冲溶液(PBS, pH=7.4)中于35 ℃下孵育30 min后, 在含有5 mmol/L K₃Fe(CN)₆/K₄Fe(CN)₆(摩尔比1:1)和0.1 mol/L KCl的PBS溶液(pH=6.0)中测定, 响应电流与PCB77浓度在0.1～160 ng/mL范围内呈良好的线性关系, R=0.9964, 检出限为0.01 ng/mL. 该传感器制备简单、 灵敏度高、 稳定性好, 可以重复使用. 将其用于检测实际污泥样品中的PCB77, 回收率为95%～112%.     

微带线电路板端口对入射电磁波的电压响应

 在考虑电磁波与电子设备的耦合时,屏蔽腔中电路板端口对入射电磁波的电压响应是一个重要的参数。分别计算了微带线电路板端口在自由空间和在屏蔽腔内这两种不同情况下的电压响应,以及屏蔽腔内耦合系数的变化。对所得结果进行了比较分析,结果表明,在自由空间时,响应电压频谱为连续的变化,而在屏蔽腔内时,只有在本征模的频率处才会激励起端口电压,频谱分布变为分立的。当屏蔽腔上开有窄缝时,窄缝方向和入射场极化方向对激励起来的端口电压都有影响,而电场极化方向和微带线方向之间的关系,是决定端口激励电压大小的关键因素。     

Improved Procedure for Single DB-XLB Column GC-MS-SIM Quantitation of PCB Congener Distributions and Characterization of Two Different Preparations Sold as “Aroclor 1254”

Complete PCB congener distributions in a panel of Aroclor mixtures were previously obtained by combining data from several HRGC systems. In that study quantitation of minor components may have been unreliable due to single level calibration against high levels of individual congener standards. Two lots of Aroclor 1254 had markedly different congener distributions. In this study, the design and performance of a congener-specific PCB analysis method employing GC-MS-SIM detection of congeners separated on a DB-XLB capillary column are discussed. Quantitation is carried out against a 6-level inclusive standard curve of a mixture of 144 congeners found in Aroclors. A separate procedure to measure trace levels of PCB 126 in Aroclors using the same system, combined with levels initially acquired for other congeners, facilitates estimation of TEQ values (Toxic Equivalencies of the PCB mixtures to 2,3,7,8-TCDD). PCB congener profiles of 15 Aroclor 1254 mixtures are presented. These profiles show that the less common, high TEQ variety of Aroclor 1254 was manufactured by an atypical, two-stage chlorination process that was apparently used during the final 1% of Aroclor 1254 production (ca. 1974–1976).     

改性糊精溶液中四氯联苯光降解途径

对改性环糊精溶液中的2,2’,4,4’-四氯联苯进行了研究,在紫外光（254nm）的照射下。2,2’,4,4’-四氯联苯的光降解产物经检测确定为含氯较少的2,4,4＇-三氯联苯及氯离子．在降解初期,各时段试样的紫外-可见扫描曲线存在明显的蓝移效果。实验结果表明,从邻位氟原子开始的脱氯反应为所试四氟联苯的主要降解途径．     

Gas Chromatographic Enantiomer Separation of Atropisomeric PCBs Using Modified Cyclodextrins as Chiral Phases

Columns containing different types of cyclodextrin derivatives have been evaluated for chiral gas chromatographic separation of atropisomeric PCBs, o,p´‐DDT and o,p´‐DDD. Separation was attempted on columns containing mixed chiral selectors, and the performance of two closely related selectors was also examined. The cyclodextrins were: permethylated‐β‐CD (PM‐β‐CD), heptakis(2,3‐di‐O‐methyl‐6‐O‐tert‐butyldimethylsilyl)‐β‐CD (2,3‐M‐6‐TBDMS‐β‐CD), heptakis(2,3‐di‐O‐methyl‐6‐O‐tert‐hexyldimethylsilyl)‐β‐CD (2,3‐M‐6‐THDMS‐β‐CD), and heptakis(2,3‐di‐O‐ethyl‐6‐O‐tert‐hexyldimethylsilyl)‐β‐cyclodextrin (2,3‐E‐6‐THDMS‐β‐CD). The cyclodextrins were dissolved in OV‐1701 or in a dimethylsiloxane/silarylene copolymer containing 5% phenyl in the backbone. The application of mixed chiral selectors led to improved separations, however; at most eleven PCB congeners were separated on a single column. Chiral resolution of o,p´‐DDD was achieved. The use of a dimethylsiloxane/silarylene copolymer as a matrix for the cyclodextrins is a promising approach. With such a matrix, blocking of the CD cavities by silicone substituent groups can be avoided, and a reasonable CD solubility can be provided. The selectivity of heptakis(2,3‐di‐O‐ethyl‐6‐O‐tert‐hexyldimethylsilyl)‐β‐CD and heptakis(2,3‐di‐O‐methyl‐6‐O‐tert‐hexyldimethylsilyl)‐β‐CD was quite different, the former selector could separate four congeners, while the latter separated ten congeners.