废弃PCB边角料的热解实验研究

废弃PCB边角料中含有大量金属及卤化阻燃剂等,它的回收一直是当今世界的重点研究课题。本文通过分析多种PCB边角料的金属成分以及热解实验研究,为PCB边角料的金属成分回收及资源再生提供了较为重要的参考数据。通过热解气体分析结果表明,热解技术运用于PCB边角料中能提高金属的回收率、减少环境污染。     

PCB甩线、铜皮分层缺陷的成因分析

PCB在生产过程中可能会产生各种缺陷,而甩线、铜皮分层是典型的PCB缺陷,通过对各种表象的PCB甩线、铜皮分层缺陷样品的分析研究,结合SEM、切片图片和EDS图表,阐述了PCB甩线、铜皮分层的主要成因。缺陷成因分析将有利于追溯缺陷形成的生产工序环节,理顺各级相关供应商责任,为供给双方更好的合作提供信赖的基础。     

基于protel互补对称性PCB新设计方法的探索

基于protel电子CAD软件,针对传统PCB设计方法不能满足PCB的专业性要求等问题,介绍了一种新的"互补对称性PCB"设计流程及实现过程,并以音响电源的"互补对称性PCB"为例,详细介绍了全新的"互补对称性PCB"的设计方法、原理以及设计技巧.     

多线程技术在基于HALCON的AOI中的应用

电子封装不断朝微型化方向发展,传统的印刷电路板(PCB)焊点检测方法已越来越难以满足生产的要求.基于机器视觉的自动光学检测(AOI)系统可对PCB焊点进行统一、可靠的快速检查,其检测速度是一个非常关键的问题.比较了单线程和多线程技术在AOI中程序运行的时间,实验表明,多线程技术的运用能使印刷电路板(PCB)的检测速度得到提高.     

浅谈PCB化学镀铜工艺环境问题及治理

随着PCB电镀行业的快速发展,电镀产生的环境问题越来越受到重点关注,PCB化学镀铜废水和污泥中含有重金属离子铜污染物,对人体和环境具有很大的危害,通过现有技术的组合搭配实现铜资源的回收,不仅可以降低环境的污染,而且还可以为企业增加效益。本文针对PCB化学镀铜工艺中的污染物分析,提出了污染物治理的建议,以供参考。     

可安全处理PCB的高温焚烧炉

众所周知，聚氯联（二）苯又称PCB且持有毒性。为了能安全处理PCB，日本协荣工业公司推出了1800C高温焚烧炉，有效地防止了有毒物质的环境污染。协荣工业公司，通过采用向炉内喷射雾状燃料，并以150m／种的高速将高温空气吹火炉内的方法处理PCB。另外，又使用了新开发的燃烧温度达2300C且燃料火焰离喷口距离为30cm的喷嘴，从而可对实际焚烧温度只有1800C的PCB进行安全处理。至于处理后的温度从1800C降至1400C以下所产生的极毒物质，高温焚烧炉设有防护装置，不必耽心泄漏扩散。可安全处理PCB的高温焚烧炉@吴伯清…     

废弃PCB的回收处理技术

废弃印刷电路板(PCB)是一种重要的有色金属二次再生资源.本文就废弃印刷电路板的元素组成和目前国内外应用较广的三种PCB回收处理技术,即湿法处理技术、火法处理技术和物理机械处理技术进行了阐述;并比较了三种技术的优缺点.     

P507萃取废弃线路板微生物浸出液中镍的研究

废弃线路板(PCB)浸出液经萃取提铜除铁后利用P507富集分离浸出液中的Ni 2+,考察萃取剂浓度、皂化率、相比(O/A)、萃取时间、浸出液pH对Ni 2+萃取率的影响。结果表明,在皂化率为30%、相比1∶1、P507浓度20%、萃取搅拌时间3min、浸出液pH 2.07的条件下,PCB微生物浸出液中Ni 2+的萃取率可达99.4%以上。     

基于萃取的印制板碱性蚀刻废液中铜的回收

PCB电路板生产过程中产生大量的碱性蚀刻废液,给当前环境带来了极大的危害问题,结合当前主流的回收技术,提出一种基于萃取法的PCB板铜离子回收方法。针对废液大部分为铜氨溶液出发,结合萃取法的原理,选择β-二酮类作为萃取剂,对铜氨废液中的铜进行萃取,进而得到在不同温度、浓度和pH值下萃取影响;同时加入H_2SO_4对回收后的溶液进行反萃取,并探讨在不同H_2SO_4浓度条件下对萃取的影响。试验结果表明,在pH=9.5,温度25℃,相比为1∶1的情况下,铜萃取浓度达到最大;同时当反萃相H_2SO_4溶液当中的氢离子浓度为4 mol/L时,其效果最佳,并达到对PCB板废液回收的目的。     

氯盐体系印刷电路板电镀锡试验研究

研究了用氯盐体系在印刷电路板(PCB板)上电镀锡，考察了相关因素对电镀锡的影响，确定了最佳工艺条件。结果表明：在温度35℃、Sn²⁺质量浓度40 g/L、电流密度2 A/dm²、盐酸浓度3 mol/L、镀锡时间6 min最佳条件下制得的锡镀层表面光亮平整且无裂缝裂纹；镀液中添加1 g/L的抗坏血酸可有效提高镀液稳定性；镀层和基体之间结合力良好，符合PCB制作过程中的要求。     

Modification by polychlorinated biphenyls (PCBs) of cadmium induced lesions in the planarian model, Dugesia dorotocephala

The appearance of abnormal growths on the planarian, Dugesia dorotocephala, in response to cadmium with and without pre-exposure to L-buthionine-R, S-sulfoximine (BSO) and concurrent exposure to the polychlorinated biphenyls (PCBs) Aroclor 1254, PCB 28, PCB 110 or PCB 126 is described. Pigmented rose thorn (PRT) lesions were non-invasive and appeared in response to PCBs. Post-head (PH) lesions developed in up to 100% of the animals within 6-20 days post-dosing, progressed rather rapidly and were highly invasive. Round tail tip (RTT) lesions appeared in lower frequencies within 10-30 days, but progressed extremely rapidly resulting in tail loss within 48 h. We have referred to these types of lesions as "tumors", but they are not necessarily characteristic of vertebrate neoplasms. PCBs interacted with cadmium in a complex way, in some cases increasing total lesions and decreasing time-to-lesion and in other cases having the opposite effects. A three-factor (PCB, PCB dose, Cd dose) nested analysis of variance model was used to determine lesion rates in order to compare PCB potencies as potentiators or antagonists. The Aroclor mixture was always the least potent co-toxicant but appeared to be the most potent antagonist; the coplanar PCB 126 was the most potent co-toxicant. The complex response surfaces and the lack of stoichiometry in dose-response relationships indicate that multiple mechanisms are responsible for PH and RTT lesions in planarians. These results emphasize the complexity of PCB toxicities and suggest further studies to validate the planarian model as a screen for combinations or environmental mixtures which may have altered biological potency in other species.     

Evaluation of Low-Temperature Test Methods for Elastomeric Bridge Bearings

Elastomeric bearings have had an exemplary performance record over the past 40 years. Recently, increased testing requirements have been imposed that now make the testing of elastomeric bearings one of the major costs in constructing the supports. Currently, four low-temperature tests are required for elastomeric bearings. It is not clear whether all these tests are necessary or in fact even related to the actual performance of an elastomeric bridge bearing since some of these tests have been developed for other materials. Research was undertaken to evaluate the various tests and to determine whether they are important or even related to the performance of the bridge bearing. Tests were conducted on full-size natural rubber and neoprene bearings at low temperature subjected to compressive and shear forces, and factors such as testing speed and thermal conditioning were evaluated. As a result of the research, some test methods and performance requirements were found to have little impact on the bearing behavior, and others were overly conservative.     

Argon laser punctal therapy versus thermal cautery for the treatment of aqueous deficiency dry eye syndrome

1. Pregnant Wistar rats were treated orally with a single dose of 100 microg 3,3',4,4'-tetrachlorobiphenyl (PCB 77)/kg b.w. or 10 microg 3,3',4,4',5 pentachlorobiphenyl (PCB 126)/kg b.w. on day 15 of pregnancy. The control rats received peanut oil at the same day. Developmental landmarks were assessed in all offspring rats and reproductive effects of PCB 77 and PCB 126 on male offspring were studied on postnatal day 65 (at puberty) and on postnatal day 140 (at adulthood). 2. The ano-genital distance as well as the ratio ano-genital distance to body length was reduced in male pups of the PCB 126 group and the age at vaginal opening was significantly delayed in the female pups. 3. Testis, brain weights and daily sperm production were permanently increased and seminal vesicle weights were decreased in male offspring of the PCB 77 group. In male rats of PCB 126 group, the brain weights were permanently increased and ventral prostate weights permanently reduced. In both PCB groups, however, serum testosterone concentration was reduced only at adulthood. Additionally, the male rats of the PCB 126 group showed alterations in sexual behavior. In these rats the number of mounts with intromissions was significantly increased. 4. The results of this study show that PCB 126 elicits some TCDD-like reproductive effects after in utero exposure, while the reproductive effects of in utero exposure to PCB 77 on male offspring may be attributed to the neonatal hypothyroidism induced by the substance during early fetal development. Further studies using multiple doses and providing thyroid hormone data will be necessary to support this hypothesis.     

Serum concentration of calcium, 1,25 vitamin D and parathyroid hormone are not correlated with coronary calcifications. An electron beam computed tomography study

As a consequence of contamination by effluents from local electronics manufacturing facilities, the New Bedford Harbor and estuary in southeastern Massachusetts is among the sites in the United States that are considered the most highly contaminated by polychlorinated biphenyls (PCBs). Since 1993, measures of intrauterine PCB exposure have been obtained for a sample of New Bedford area infants. Among 122 mother-infant pairs, we identified four milk samples with total PCB levels that were significantly higher than the rest, with estimated total PCBs ranging from 1,100 to 2,400 ng/g milk fat compared with an overall mean of 320 ng/g milk fat for the 122 women. The congener profile and history of one case was consistent with past occupational PCB exposures. Otherwise, the source of PCB exposures in these cases was difficult to specify. Environmental exposures including those from fish consumption were likely, whereas residence adjacent to a PCB-contaminated site was considered an unlikely exposure source. In all four cases, the infants were full-term, healthy newborns. Because the developing nervous system is believed to be particularly susceptible to PCBs (for example, prenatal PCB exposures have been associated with prematurity, decrements in birth weight and gestation time, and behavioral and developmental deficits in later infancy and childhood, including decrements in IQ), it is critical to ascertain if breast-feeding is a health risk for the women's infants. Despite the potential for large postnatal PCB exposures via breast milk, there is limited evidence of significant developmental toxicity associated with the transmission of moderate PCB concentrations through breast milk. Breast-feeding is associated with substantial health benefits including better cognitive skills among breast-fed compared with formula-fed infants. We conclude, based on evidence from other studies, that the benefits of breast-feeding probably outweigh any risk from PCB exposures via breast milk among the four New Bedford infants. In this case report, PCB analysis of breast milk and infant cord serum was a research tool. PCB analysis of milk is rarely done clinically, in part because it is difficult to use the results of such analyses to predict health risks. Substantial effort is needed to achieve a better understanding of the clinical and public health significance of PCB exposures, particularly among potentially susceptible groups such as infants and children. Such efforts are critical to improving the clinical and public health management of widespread and ongoing population exposures to PCBs.     

Constructability Test for Cold In-Place Asphalt Recycling

Unstable subgrades are a major constructability problem for cold in-place asphalt recycling. The recycling operation is often performed by a train of equipment that mills, screens, crushes, and mixes the recycled material. This train is supported by the remaining pavement after the top has been milled off for recycling. Because the remaining pavement may be as little as 1 or 2 in. thick, good subgrade stability is required to support the train. A test is developed to assess subgrade stability using a dynamic cone penetrometer. The testing instrument is inexpensive and portable, and the initial testing program can be carried out for a typical project in 1 or 2 days. Guidelines are developed using data from a project that developed varying levels of subgrade instability during construction. The guidelines were corroborated by testing on other projects. The test may be used on projects having glacial till derived soil subgrades and in which equipment is supported by 1 or 2 in. of remaining pavement plus a soil-aggregate base. Additional research is recommended to develop test guidelines for different types of soils and different base support conditions.     

电子浆料材料的研究进展及其在印刷电路板方面的应用

介绍了电子行业广泛应用的电子浆料,着重讨论了电子浆料材料的组成、制备方法及以后的发展趋势。阐述了印刷电路板(PCB)技术和可喷印的电子浆料材料,并探讨了电子浆料材料在喷印技术方面的应用,以及电子浆料材料对于印刷电路板的重要性和未来可能的发展趋势。     

Cytochromes P450, P420 & mixed-function oxidases as biomarkers of polychlorinated biphenyl (PCB) exposure in harbour seals (Phoca vitulina)

Hepatic microsomal cytochrome P450, EROD and ECOD activity were investigated as biomarkers of PCB exposure in harbour seals (Phoca vitulina). Due to the difficulty of obtaining undegraded seal liver samples, standard spectrophotometric methodology was adapted to investigate P420 (degraded P450) as a PCB biomarker with partially degraded samples. Total PCB burdens in both blubber and liver had positive correlations with P450, P420 and MFO activity levels. The use of P420 biomarkers in this study supports the inclusion of samples from by-caught marine mammals for future biomonitoring studies. P450 isozymes CYP1A (P4501A) and CYP2B (P4502B) in conjunction with MFO activity were investigated as "specific" biomarkers of PCB exposure. They were found to reliably reflect levels of [MC] and [PB]-type PCB exposure in harbour seal liver.     

印刷电路板边角料中金属含量的分析

废弃印刷电路板中含多种有价金属,对这些金属进行回收利用成了当前的一个研究热点。由于印刷电路板中含大量的有机物及取样均匀性等问题的制约,无法用仪器直接对其进行分析。本实验通过一个简单的低温焙烧,排除有机物对后续分析的干扰,然后对分析结果进行简单的数学处理,可以得到废旧印刷电路板中金属的含量,为工业回收电路板中的金属提供准确的数据。     

Effect of Oil on Polychlorinated Biphenyl Phase Partitioning during Land Biotreatment of Impacted Sediment

This study evaluated the partitioning of polychlorinated biphenyls (PCBs) during long-term, passive, land biotreatment of PCB-impacted industrial lagoon sediments. Over six years under field conditions, two land treatment units (LTUs) experienced 40% total PCB reductions from initial concentrations of 8–10?mg/kg. A third LTU with 113?mg/kg initial total PCBs showed little reduction over five years. In each unit throughout the study, oil concentrations declined at a rate greater than that for PCBs. Measured aqueous equilibrium concentrations for the PCB-impacted sediments were typically an order of magnitude or more smaller than values estimated using correlations based on total organic matter partitioning. Measured aqueous PCB concentrations agreed with predictions based on equilibration with a PCB-containing oil phase, best modeled by Raoult’s law. It was postulated that, as a consequence of PCB oil-phase partitioning, biotreatment would lead to higher PCB concentrations in the oily matter and thus increased PCB partitioning to the aqueous phase if the degradation of oily matter proceeded faster compared to PCBs. Such was the case in this study, wherein low-level aqueous phase PCB concentrations of tetrachloro PCBs increased several fold over the years as oily matter was degraded. The contribution of oil to PCB partitioning needs to be incorporated in the assessment of risk and treatability goals for land biotreatment of contaminated sediments from industrial sites.     

Ethoxyresorufin-O-deethylase (EROD) inducing potencies of planar chlorinated aromatic hydrocarbons in primary cultures of hepatocytes from different developmental stages of the chicken

In vitro induction of ethoxyresorufin O-deethylase (EROD) activity in cell cultures is an extensively validated tool for measuring overall potencies of mixtures of halogenated aromatic hydrocarbons (HAHs) in samples from the abiotic or biotic environment. For risk assessment with special attention to effects in wild birds, an assay was developed that makes use of chicken embryo hepatocytes. However, it was questioned whether compound-specific responses are consistent at the various developmental stages. The results of our present study show that there are considerable differences between early and late embryonal and post-hatching stages. The induction of EROD was measured in primary chicken hepatocyte cultures. The cells were isolated at day 14 and day 19 of embryonal development and at day 1 post hatching. Hepatocytes were exposed in vitro to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 3,3',4,4',5-pentachlorobiphenyl (PCB 126, IUPAC nomenclature) and 2,3',4,4',5-pentachlorobiphenyl (PCB 118). The respective compounds were chosen as representatives for dioxins, furans, non-ortho PCBs, and mono-ortho PCBs. These groups of chemicals have been identified as environmental contaminants with major dioxin-like effects that are mediated by a common receptor, the arylhydrocarbon (Ah) receptor. At all developmental stages, TCDF was more potent than TCDD. Relative potencies (RP = EC50TCDD/EC50HAH) decreased in the order TCDF < TCDD < PCB 126 < PCB 118. Depending on the developmental stage, TCDF was 1.2 to 3.4 times more potent than TCDD. PCB 126 was equipotent or less potent by a factor of 3 than TCDD. PCB 118 was 100 to 300 times less potent than TCDD. Both the mean effective concentration (EC50) and the maximum EROD activity (Ymax) of all compounds were lower in hepatocyte cultures from 14-day-old embryos than those from 19-day-old embryos or 1-day-old hatchlings. RPs were comparable in 19-day-old embryos and in hatchlings, but significantly different in 14-day-old embryos.