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In this paper, we present a novel polylactic-acid/flax-composite substrate and the implementation of a demonstrator: a microcontroller board based on commercial design. The substrate is developed for printed circuit board (PCB) applications. The pre-preg is biodegradable, reinforced, and flame-retarded. The novel material was developed to counter the increasing amount of e-waste and to improve the sustainability of the microelectronics sector. The motivation was to present a working circuit in commercial complexity that can be implemented on a rigid substrate made of natural, bio-based materials with a structure very similar to the widely used Flame Retardant Class 4 (FR4) substrate at an early technological readiness level (2–3). The circuit design is based on the Arduino Nano open-source microcontroller board design so that the demonstration could be programmable and easy to fit into education, IoT applications, and embedded designs. During the work, the design was optimized at the level of layout. The copper-clad pre-preg was then prepared and processed with subtractive printed wiring technology and through hole plating. The traditional surface mounting methodology was applied for assembly. The resulting yield of PCB production was around 50%. Signal analysis was successful with analogue data acquisition (voltage) and low-frequency (4 kHz) tests, indistinguishable from sample FR4 boards. Eventually, the samples were subjected to highly accelerated stress test (HAST). HAST tests revealed limitations compared to traditional FR4 printed circuit materials. After six cycles, the weight loss was around 30% in the case of PLA/Flax, and as three-point bending tests showed, the possible ultimate strength (25 MPa at a flexural state) was reduced by 80%. Finally, the sustainability aspect was assessed, where we found that ∼95 vol% and ∼90 wt% of the traditional substrate can be substituted, significantly easing the load of waste on the environment. [ABSTRACT FROM AUTHOR]

Due to the continuous increase in the globalized outsourcing of printed circuit board (PCB) fabrication, PCB counterfeits have increased by a significant margin, necessitating rapid and advanced hardware assurance techniques. PCB image segmentation is the primary step in PCB assurance. Over the years, few PCB component segmentation methods have been proposed, and none of those has provided a definite performance benchmark. Besides, those methods have not discussed how the performance is correlated with underlying data or annotation quality. This work presents a PCB image segmentation benchmark. In addition, we explore how annotation quality affects component segmentation and present possible future research directions to work with coarse annotations to alleviate the human effort behind full data annotation tasks. We have analyzed the performance of the preferred deep neural network (DNN) architecture and Transformer architecture with the data annotation quality and presented the direction to leverage the outcome with limited quality annotations. Finally, we present the qualitative as well as the quantitative results to demonstrate the performance of our techniques and provide observations and future research directions on the overall task. [ABSTRACT FROM AUTHOR]

The EPFL Spacecraft Team (EST) is working on the Constellation of High-Performance Exospheric Science Satellites (CHESS) mission, which aims to launch a constellation of two CubeSats in 2027. These CubeSats will study the chemical composition of Earth's exosphere using time-of-flight mass spectrometry. To downlink the collected scientific data, the satellites will utilise a custom X-band transceiver, presented in this paper, operating in the amateur frequency range of 10.45 GHz to 10.50 GHz. The proposed transceiver architecture employs Software-Defined Radio (SDR) technology and can be easily adapted for different use cases. This modular approach has the potential to be suitable for future spacecraft missions, such as active debris removal or lifetime extension services, where flexible communication systems are required. • Hybrid SDR architectures enable versatile telecom systems for space missions. • IOD/IOV missions let students follow the entire life cycle of a space project. • Short development/prototyping cycles maximise the lessons learned in student teams. [ABSTRACT FROM AUTHOR]

This study focuses on the effects of reducing the diameter of rivets used in Friction Riveting due to the need for downscaling when joining assemblies on a smaller scale. The Friction Riveting process has shown promising feasibility for a variety of material combinations and applications in the transportation industry. Recent research has explored the potential application of this technique in electronics, specifically for the assembly of printed circuit boards (PCBs), using AA-2024-T351 rivets on thin glass-fiber-reinforced epoxy substrates (FR4). The joint formation of joints produced with PCBs was investigated in terms of process temperature evolution, microstructural changes, and mechanical properties. Joints were obtained at process temperatures ranging from 285 ºC to 368 ºC. The use of 4 mm rivets resulted in extensive delamination, weak joint mechanisms, and cracking, impaired by the different coefficients of thermal expansion of the materials involved. Reducing the rivet diameter to 3 mm significantly improved joint quality. A further reduction to 2.5 mm minimized delamination but led to insufficient anchorage and cracking. Joints produced with a 3 mm rivet diameter achieved the highest ultimate tensile force of 276 N. This study sets the foundation for applying the Friction Riveting process to practical PCB assemblies, demonstrating that optimizing the process parameters to the diameter-to-thickness ratio can balance sufficient rivet anchoring, minimize delamination, and reduce cracking. [ABSTRACT FROM AUTHOR]

BACKGROUND: The rapid development of industrialization in printed circuit board (PCB) warrants more complexity and integrity, which entails an essential procedure of PCB inspection. X-ray computed laminography (CL) enables inspection of arbitrary regions for large-sized flat objects with high resolution. PCB inspection based on CL imaging is worthy of exploration. OBJECTIVE: This work aims to extract PCB circuit layer information based on CL imaging through image segmentation technique. METHODS: In this work, an effective and applicable segmentation model for PCB CL images is established for the first time. The model comprises two components, with one integrating edge diffusion and l0 smoothing to filter CL images with aliasing artifacts, and the other being the fuzzy energy-based active contour model driven by local pre-fitting energy to segment the filtered images. RESULT: The proposed model is able to suppress aliasing artifacts in the PCB CL images and has good performance on images of different circuit layers. CONCLUSIONS: Results of the simulation experiment reveal that the method is capable of accurate segmentation under ideal scanning condition. Testing of different PCBs and comparison of different segmentation methods authenticate the applicability and superiority of the model. [ABSTRACT FROM AUTHOR]

Electronic components are the main components of PCBs (printed circuit boards), so the detection and classification of ECs (electronic components) is an important aspect of recycling used PCBs. However, due to the variety and quantity of ECs, traditional target detection methods for EC classification still have problems such as slow detection speed and low performance, and the accuracy of the detection needs to be improved. To overcome these limitations, this study proposes an enhanced YOLO (you only look once) network (EC-YOLOv7) for detecting EC targets. The network uses ACmix (a mixed model that enjoys the benefits of both self-attention and convolution) as a substitute for the 3 × 3 convolutional modules in the E-ELAN (Extended ELAN) architecture and implements branch links and 1 × 1 convolutional arrays between the ACmix modules to improve the speed of feature retrieval and network inference. Furthermore, the ResNet-ACmix module is engineered to prevent the leakage of function data and to minimise calculation time. Subsequently, the SPPCSPS (spatial pyramid pooling connected spatial pyramid convolution) block has been improved by replacing the serial channels with concurrent channels, which improves the fusion speed of the image features. To effectively capture spatial information and improve detection accuracy, the DyHead (the dynamic head) is utilised to enhance the model's size, mission, and sense of space, which effectively captures spatial information and improves the detection accuracy. A new bounding-box loss regression method, the WIoU-Soft-NMS method, is finally suggested to facilitate prediction regression and improve the localisation accuracy. The experimental results demonstrate that the enhanced YOLOv7 net surpasses the initial YOLOv7 model and other common EC detection methods. The proposed EC-YOLOv7 network reaches a mean accuracy (mAP@0.5) of 94.4% on the PCB dataset and exhibits higher FPS compared to the original YOLOv7 model. In conclusion, it can significantly enhance high-density EC target recognition. [ABSTRACT FROM AUTHOR]

In this paper, a triband bandpass filter has been proposed for millimeter wave and 5G applications. The filter design is progressed using a complementary spiral resonator superimposed on a hexagonal patch measuring about 7 mm × 4.2 mm × 0.8 mm. employing Rogers 5880 as substrate with εr = 2.2. This triband filter is highly selective with sharp rejections emulating bandwidths of about 1.3 GHz, 2.5 GHz, and 1.8 GHz capable of supporting millimeter wave and 5G communications. The qualifying parameters of filter-like insertion loss have been realized between −0.6 dB and −0.16 dB and return loss between −19.12 dB and −28 dB for the corresponding three bands. Moreover, the performance attainment of the filter has been verified from the surface current distribution of the filter. The filter resonates at millimeter wave frequencies of 29.6 GHz, 32.5 GHz, and 35.8 GHz portraying a triband response. The simulated and measured results substantiated very well with each other. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency and accuracy of multitarget detection of soldering defects on surface-mounted components in Printed Circuit Board (PCB) fabrication, we propose a sample generation method using Stable Diffusion Model and ControlNet, as well as a defect detection method based on the Swin Transformer. The method consists of two stages: First, high-definition original images collected in industrial production and the corresponding prompts are input to Stable Diffusion Model and ControlNet for automatic generation of nonindependent samples. Subsequently, we integrate Swin Transformer as the backbone into the Cascade Mask R-CNN to improve the quality of defect features extracted from the samples for accurate detection box localization and segmentation. Instead of segmenting individual components on the PCB, the method inspects all components in the field of view simultaneously over a larger area. The experimental results demonstrate the effectiveness of our method in scaling up nonindependent sample datasets, thereby enabling the generation of high-quality datasets. The method accurately recognizes targets and detects defect types when performing multitarget inspection on printed circuit boards. The analysis against other models shows that our improved defect detection and segmentation method improves the Average Recall (AR) by 2.8% and the mean Average Precision (mAP) by 1.9%. [ABSTRACT FROM AUTHOR]

Aiming at the problems of low accuracy and slow detection rate of existing target detection algorithms for PCB defect detection, and too many parameters of algorithm model leading to the inability to deploy on mobile terminals, a PCB defect detection algorithm based on MSD-YOLOv5 is proposed. Firstly, to ensure both detection accuracy and speed while reducing the model's size,we combine the lightweight MobileNet-v3 network with the CSPDarknet53 network. Further,the attention mechanism is introduced to highlight the important feature channels and weaken the less useful ones, so as to improve the feature extraction ability of the network. Finally, the coupling detection head is replaced with a decoupling detection head, and the defect location information and category information on the PCB are extracted and learned respectively, which solves the problem of highly coupling of different information feature distributions and enhances the generalization ability of the model. We conduct experiments on a publicly available PCB defect dataset from Peking University using this algorithm. The results show that the proposed method reduces the parameters of YOLOv5 model by 46% and improves the detection accuracy by 3.34%. [ABSTRACT FROM AUTHOR]

With the constant advancement of electronic science and technology, accurate failure analysis has become crucial to meeting stringent quality standards in surface mount (SMT) products. Reflow soldering is commonly used in the SMT industry due to its efficiency and low failure rate. However, visual inspection is limited, especially for ball grid array (BGA) joints, requiring X-ray techniques for complete, non-destructive analysis. Although X-ray image analysis algorithms have been employed to improve defect detection, some still need to meet quality requirements, resulting in additional manual inspections. The high dimensionality and variations in X-ray images present additional challenges for detection algorithms. This study proposes a new computer-assisted inspection approach to accurately detect flaws in solder joints of SMD components using an X-ray scanning system. This approach aims to improve image interpretation and reduce workload manual. X-ray technology applied to BGA seeks to improve the accuracy of image analysis, enabling the detection of various faults, such as BGA ball connections, interconnections on printed circuit boards, and filling faults. [ABSTRACT FROM AUTHOR]

Today's unique assembly challenges are comprised of complex printed circuit board (PCB) panelization, involving identical PCBs with a goal of increased production capability, due to a reduced footprint of the production floor. Identical PCBs that are within the same panel, with uniform spacing in an array or carrier, need to be dispensed at the same time. All these high-mix challenges have gone mainstream and affect real productivity and throughput. Existing manual dual-head dispensing systems do not consider the rotational correction for the second head, which leads to yield loss. To eliminate the yield loss on the second head, there is a mini XY drive system incorporated that provides fast and accurate dispensing to double the process capabilities over the same work area. Dynamic dual-head (DDH) dispensing uses a unique mini XY drive system on the left head, mounted on a separate Z-axis, to dynamically control the position of the head for accurately aligning to a second part, while synchronously dispensing both parts. The machine vision system performs the substrate alignment for each identical PCB that is individually placed in a carrier, which provides greater potential for variation in offset and skew. During synchronous dispensing for the second part with the DDH all the kinematic adjustment is performed with calculated values, from the skew angle and scaling factor. This technique guarantees increased productivity whilst maintaining yields through unsurpassed accuracy. DDH also provides the same level of adjustment and rotational correction for all step and repeated PCBs, flex circuits, and panel designs. If a product contains an odd number of units, then either of the heads can be programmed for dispensing while the others cannot. This paper examines proven methods to determine the dot/line positional accuracy along with the mass flow rate for both heads during synchronous dispensing. This paper will also address the challenges faced, and how the rotational correction can achieve up to 23 higher throughput than existing single/dual head dispensing systems. [ABSTRACT FROM AUTHOR]

Multilayer printed circuit boards (PCBs) can be produced not only in the traditional way but also additively. Both traditional and additive manufacturing can lead to invisible defects in the internal structure of the electronic component, eventually leading to the spontaneous failure of the device. No matter what kind of technology is used for the production of PCBs, when they are used in important structures, quality control is important to ensure the reliability of the component. The nondestructive testing (NDT) of the structure of manufactured electronic components can help ensure the quality of devices. Investigations of possible changes in the structure of the product can help identify the causes of defects. Different types of manufacturing technologies can lead to diverse types of possible defects. Therefore, employing several nondestructive inspection techniques could be preferable for the inspection of electronic components. In this article, we present a comparison of various NDT techniques for the evaluation of the quality of PCBs produced using traditional and additive manufacturing technologies. The methodology for investigating the internal structure of PCBs is based on several of the most reliable and widely used technologies, namely, acoustic microscopy, active thermography, and radiography. All of the technologies investigated have their advantages and disadvantages, so if high-reliability products are to be produced, it would be advantageous to carry out tests using multiple technologies in order to detect the various types of defects and determine their parameters. [ABSTRACT FROM AUTHOR]

From 2010 to 2022, the summed concentrations of six indicator polychlorinated biphenyls (∑6PCB) and DDT with metabolites DDE and DDD (∑DDT) in the surface layer of the coastal Black Sea areas of Crimea varied from 0.05 to 34.9 and from 0.01 to 7.44 ng/L, respectively. The maximum concentrations of both groups of compounds were found during spring seasons. With the total variability in the ∑DDT content in water being significant, their average concentration tended to decrease in the study period. For PCBs, this trend was not detected. The ∑DDT concentration in mesozooplankton in the studied water areas in 2016, 2017, and 2019 reached 34.3; ∑6PCB, 475 ng/g dry weight. A positive correlation between the ∑DDT concentration in mesozooplankton and water samples (R 2 = 0.77) and the lack of such correlation for ∑PCB (R 2 = 0.03) was revealed. It was determined that the accumulation of ∑PCB and ∑DDT in mesozooplankton was directly correlated with the total lipid content in organisms. In the surface layer of sediments in open areas of the Black Sea water area of Crimea, the content of PCB congeners 101, 138, 153, and 180 was the same in 2016 and 2019, which indicates stabilization of the technogenic load on the studied water areas. [ABSTRACT FROM AUTHOR]

This review summarises our two decades of polychlorinated biphenyl (PCB) monitoring in different marine organisms along the eastern Adriatic Sea. The aim was to gain an insight into the trends of PCB distribution in order to evaluate the effectiveness of past and current legislation and suggest further action. Here we mainly focus on PCB levels in wild and farmed Mediterranean mussels, wild and farmed bluefin tuna, loggerhead sea turtles, common bottlenose dolphins, and small pelagic fish. The use of artificial intelligence and advanced statistics enabled an insight into the influence of various variables on the uptake of PCBs in the investigated organisms as well as into their mutual dependence. Our findings suggest that PCBs in small pelagic fish and mussels reflect global pollution and that high levels in dolphins and wild tuna tissues raise particular concern, as they confirm their biomagnification up the food chain. Therefore, the ongoing PCB monitoring should focus on predatory species in particular to help us better understand PCB contamination in marine ecosystems in our efforts to protect the environment and human health. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are persistent organic toxicants derived from legacy pollution sources and their formation as inadvertent byproducts of some current manufacturing processes. Metabolism of PCBs is often a critical component in their toxicity, and relevant metabolic pathways usually include their initial oxidation to form hydroxylated polychlorinated biphenyls (OH-PCBs). Subsequent sulfation of OH-PCBs was originally thought to be primarily a means of detoxication; however, there is strong evidence that it may also contribute to toxicities associated with PCBs and OH-PCBs. These contributions include either the direct interaction of PCB sulfates with receptors or their serving as a localized precursor for OH-PCBs. The formation of PCB sulfates is catalyzed by cytosolic sulfotransferases, and, when transported into the serum, these metabolites may be retained, taken up by other tissues, and subjected to hydrolysis catalyzed by intracellular sulfatase(s) to regenerate OH-PCBs. Dynamic cycling between PCB sulfates and OH-PCBs may lead to further metabolic activation of the resulting OH-PCBs. Ultimate toxic endpoints of such processes may include endocrine disruption, neurotoxicities, and many others that are associated with exposures to PCBs and OH-PCBs. This review highlights the current understanding of the complex roles that PCB sulfates can have in the toxicities of PCBs and OH-PCBs and research on the varied mechanisms that control these roles. [ABSTRACT FROM AUTHOR]

AbstractAlthough the sensitivity of receptor models to seeding methods, random noise, and sample size are frequently discussed in environmental forensics, a rigorous evaluation of these factors has been lacking. We generated 435,600 unique datasets with between two and seven sources of PCBs or PFAS that attempt to approximate real-world environmental datasets. Evaluation of these simulated datasets with PVA shows that EXRAWC and NNDSVD seeding methods converge more often and are typically more accurate when sources are similar to each other or are present in small proportions. The results also show that increasing sample sizes up to 25 samples can improve predictive accuracy. [ABSTRACT FROM AUTHOR]

Modern wireless communication systems are of utmost importance to various sectors such as healthcare, education, the household, and the advancement of emerging technologies like the internet of things, autonomous vehicles, and the enhancement of 5G. Further development and improvement of these systems drives the need for small dimension, high integration and density, and cost-effective electronic devices. Achieving optimal performance in wireless electronic devices involves overcoming engineering challenges related to microstrip line signal integrity. This research addresses the impact of surface mount technology (SMT) component pads on signal integrity, proposing a novel high-frequency microstrip line structure for mitigating impedance discontinuities. The study introduces stepped microstrip lines and explores characteristic impedance compensation techniques. A six-layer printed circuit board (PCB) structure is presented, and the effects of compensation on signal integrity are analyzed using time-domain reflectometry and scattering parameter measurements. The results demonstrate the effectiveness of compensation methods in aligning characteristic impedance with desired values, thereby ensuring improved impedance matching and transmission coefficients. The average over-the-length impedance for the proposed structure with compensation applied was measured to be 52.7 Ω, which is only 1.3 Ω (2.5%) more than that of the reference microstrip. Applying reference plane cut-outs leads to a maximum compensated absolute value of more than 30 Ω to reach the target impedance with a 10% tolerance. This research contributes valuable insights for advancing wireless communication systems and maintaining robustness in high-frequency microstrip transmission lines. [ABSTRACT FROM AUTHOR]

The paper presents the possibility of recovering metals from printed circuit boards (PCBs) of spent mobile phones using the hydrometallurgical method. Two-stage leaching of Cu(II), Fe(III), Sn(IV), Zn(II), Ni(II) and Pb(II) with H2SO4 (2 and 5 M) and HNO3 (2 M) with the addition of H2O2 (10 and 30%) and O3 (9 or 15 g/h) was conducted at various process conditions (temperature—313, 333 and 353 K, time—60, 120, 240, 300 min, type and concentration of leaching agent, type and concentration of oxidant, solid–liquid ratio (S/L)), allowing for a high or total metals leaching rate. The use of two leaching stages allows for the preservation of selectivity, separation and recovery of metals: in the first stage of Fe(III), Sn(IV) and in the second stage of the remaining tested metal ions, i.e., Cu(II), Zn(II), Ni(II) and Pb(II). Removing Fe from the tested PCBs' material at the beginning of the process eliminates the need to use magnetic methods, the purpose of which is to separate magnetic metal particles (ferrous) from non-magnetic (non-ferrous) particles; these procedures involve high operating costs. Since the leaching of Cu(II) ions with sulfuric(VI) acid practically does not occur (less than 1%), this allows for almost complete transfer of these ions into the solution in the second stage of leaching. Moreover, to speed up the process and not generate too many waste solutions, oxidants in the form of hydrogen peroxide and ozone were used. The best degree of leaching of all tested metal ions was obtained when 2 M sulfuric(VI) acid at 353 K was used in the 1st research stage, and 2 M nitric(V) acid and 9 g/h O3 at 298 K in the 2nd stage of leaching, which allowed it to be totally leached 100% of Fe(III), Cu(II), Sn(IV), Zn(II), Ni(II) and 90% Pb(II). [ABSTRACT FROM AUTHOR]

Printed Circuit Board (PCB) serves as the fundamental backbone of the modern electronics industry, providing essential support and connectivity for a wide range of electronic components within electronic devices. This research paper provides an overview of PCB defect detection techniques and different categories of defects. Various defects have been identified using current methods; however, certain defects persist undetected. This paper offers insight that can propel researchers towards innovations in this domain, coupled with a thorough exploration of potential enhancements. A total of twelve papers have been taken into account, and this survey examines the papers spanning from the years 2019 to 2023. The goal is to provide a comprehensive review of cutting-edge techniques, the models used, their accuracies, defects detected, and improvements, intending to advance the field of PCB defect detection. It also outlines potential avenues for further research, making it a valuable resource for researchers seeking to enhance this field in the future. The survey encompasses diverse detection techniques, which include algorithms based on the CNN, MobileNet, YOLO, SSD, and FPN models, etc. By comparing their accuracy, researchers can gain valuable insights into the effectiveness of each approach for different types of PCB defects. The paper also addresses the limitations of existing methods, identifying areas for improvement and future scope. In conclusion, this study is a valuable resource for researchers, engineers, and business professionals involved in the fields of electronics manufacturing and quality control. By consolidating a diverse range of techniques and insights, it paves the way for the development of more sophisticated, accurate, and cost-effective PCB defect detection techniques that guarantee the performance and dependability of electrical equipment in all industries. [ABSTRACT FROM AUTHOR]

From 2010 to 2022, the summed concentrations of six indicator polychlorinated biphenyls (∑6PCB) and DDT with metabolites DDE and DDD (∑DDT) in the surface layer of the coastal Black Sea areas of Crimea varied from 0.05 to 34.9 and from 0.01 to 7.44 ng/L, respectively. The maximum concentrations of both groups of compounds were found during spring seasons. With the total variability in the ∑DDT content in water being significant, their average concentration tended to decrease in the study period. For PCBs, this trend was not detected. The ∑DDT concentration in mesozooplankton in the studied water areas in 2016, 2017, and 2019 reached 34.3; ∑6PCB, 475 ng/g dry weight. A positive correlation between the ∑DDT concentration in mesozooplankton and water samples (R 2 = 0.77) and the lack of such correlation for ∑PCB (R 2 = 0.03) was revealed. It was determined that the accumulation of ∑PCB and ∑DDT in mesozooplankton was directly correlated with the total lipid content in organisms. In the surface layer of sediments in open areas of the Black Sea water area of Crimea, the content of PCB congeners 101, 138, 153, and 180 was the same in 2016 and 2019, which indicates stabilization of the technogenic load on the studied water areas. [ABSTRACT FROM AUTHOR]

Automated visual inspection on PCB boards is a critical process in electronic industries. Misalignment component detection is one of the challenging tasks in the PCB inspection process. Defects during the production process might include missing and misaligned components as well as poor solder connections. Inspection of PCB is therefore required to create practically defect-free products. There are various methods have been developed to perform this task in literature. The significance of this research is to propose an efficient with low-cost system is still require in small scale manufacturing to perform the misalignment or missing component detection on PCB boards. However, an efficient, low-cost system is still required in small-scale manufacturing to perform the misalignment or missing component detection on PCB boards. In this study, a real-time visual inspection system is developed for misalignment component detection. The proposed system consists of hardware and software frameworks. The hardware framework involves the setup of devices and modules. The software framework is composed of pre-processing and post-processing. In pre-processing, image enhancement is applied to remove noises from captured images and You Only Look Once (YOLO) object detector for components detection. Subsequently, the detected components are compared to the corresponding defined pattern using a template-matching algorithm. As experimental shown, the proposed system satisfies the requirement of missing component detection on PCB boards. [ABSTRACT FROM AUTHOR]

Persistent organic pollutants (POPs) are well-known contaminants that raise serious concerns, even more than 20 years after they were banned. Their worldwide distribution and persistence necessitate continuous monitoring in all components of the environment. The most challenging issues of POP regulation are associated with international water resources because their solutions require international cooperation in environment protection. This review provides data on various POPs (DDT, HCH, endrin, dieldrin, and PCBs) and their concentrations in aquatic organisms inhabiting the Amur River basin, one of the most poorly explored regions of Northeast Asia. Most studies have been conducted in the Songhua River (China), a tributary of the Amur River, which indicates that large inland bodies of water, especially those of international importance, require more extensive research. [ABSTRACT FROM AUTHOR]

Concrete is a widely used construction material, demanding strict quality control to maintain its integrity. The durability and lifespan of concrete structures rely heavily, amongst other factors, on the characteristics of fresh and early age concrete, which are strongly dependent on the curing process. To ensure long-term durability, it is crucial to assess concrete properties throughout construction and verify compliance with design specifications. Currently, electrical resistivity-based sensors are available and used for quality control and monitoring, however, these sensors tend to be costly or only measure at a single location within the concrete cover. This study introduces a printed circuit board (PCB)-based array of electrodes capable of measuring concrete resistivity profiles across the concrete cover, from its fresh state to early age development. In this work, the feasibility of such resistivity PCB-sensors, novel for concrete, is evaluated under laboratory conditions. The sensors exhibit a promising performance in monitoring the efficiency of concrete curing under various conditions. Additionally, they successfully evaluate the effectiveness of internal curing (in our study, promoted by superabsorbent polymers) during the initial stages of hardening. This sensor array provides a valuable tool for monitoring the curing of concrete at early age, and showcases a preliminary solution that could be further developed to ensure long-term performance of concrete infrastructure. [ABSTRACT FROM AUTHOR]

Digital tomosynthesis (DTS) technology has attracted much attention in the field of nondestructive testing of printed circuit boards (PCB) due to its high resolution and suitability to thin slab objects. However, the traditional DTS iterative algorithm is computationally demanding, and its real-time processing of high-resolution and large volume reconstruction is infeasible. To address this issue, we in this study propose a multiple multi-resolution algorithm, including two multi-resolution strategies: volume domain multi-resolution and projection domain multi-resolution. The first multi-resolution scheme employs a LeNet-based classification network to divide the roughly reconstructed low-resolution volume into two sub-volumes namely, (1) the region of interest (ROI) with welding layers that necessitates high-resolution reconstruction, and (2) the remaining volume with unimportant information which can be reconstructed in low-resolution. When X-rays in adjacent projection angles pass through many identical voxels, information redundancy is prevalent between the adjacent image projections. Therefore, the second multi-resolution scheme divides the projections into non-overlapping subsets, using only one subset for each iteration. The proposed algorithm is evaluated using both the simulated and real image data. The results demonstrate that the proposed algorithm is approximately 6.5 times faster than the full-resolution DTS iterative reconstruction algorithm without compromising image reconstruction quality. [ABSTRACT FROM AUTHOR]

The chemical contamination in fruit and vegetables represents a challenging analytical issue, with tomatoes deserving to be investigated as they are fundamental components of the Mediterranean diet. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs contamination is of serious concern, due to particulate deposition and to uptake from contaminated soils and water. However, time-consuming, non-simultaneous and/or non-eco-friendly extraction procedures are typically used to investigate organic contamination in tomatoes, with nitro-PAHs that have not yet been studied. Based on these premises, this work reports the development of a QuEChERS-based approach, coupled with gas chromatography/mass spectrometry, for the simultaneous determination of 16 PAHs, 14 PCBs and 4 nitro-PAHs in three tomato cultivars. The effect of dichloromethane, cyclohexane and acetone, as well as of four clean-up phases were studied through the advanced combination of full factorial experimental design and multiple response optimization approaches. The final protocol, based on cyclohexane extraction followed by a double purification step with primary secondary amine and octadecyl silica and a sulfuric acid oxidation, led to 60–120% recoveries (RSD% < 15%). Good repeatability (inter-day precision <15%) and negligible matrix effect (<16%) were confirmed and the protocol was applied to the analysis of real tomato samples purchased in a local market. [ABSTRACT FROM AUTHOR]

The presence of persistent organic pollutants (POPs) in human milk is an indicator of the level of these substances in the environment and enables evaluation of the potential exposure of breastfed children. POPs concentrations in a Moroccan human milk pooled sample (59 donors) were determined for the first time by the WHO reference laboratory to provide a baseline and allow monitoring of the future trends for those persistent organohalogen compounds. Eighty-one different POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dioxins and furans (PCDD/Fs) were identified and quantified by using gas chromatography (GC) with an electron capture detector (ECD) and confirmed by gas chromatography-mass spectrometry (GC/LRMS). The obtained results showed that the sum of DDT (sum of o,p'-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, o,p'-DDT, and p,p′-DDT) was 237.9 ng/g, representing 94.0% of all detected OCPs levels, with a dominance of p,p′-DDE, and p,p′-DDT. Cis-heptachlor epoxide, HCB, and HCH were found at much lower levels. PCB indicator level was 60.7 ng/g of lipid, with the dominance of PCB 138, PCB 153, and PCB 180, presenting 98.3% of the total. Among the 25 PBDE congeners quantified, BDE-47, BDE-153, BDE-197, and BDE-207 were the dominant congeners account for 15.4% of the total concentration of PBDE (1.3 pg/g lipid). The lipid-adjusted level of PCDD/Fs and dl-PCBs expressed in Toxic Equivalents (TEQs: 6.65 pg/g) were lower in comparison to those found in the other countries. In summary, detected POPs levels in Moroccan human milk were much lower compared to the other countries, reflecting the effectiveness of the compliance with Stockholm Convention requirements on eliminating or reducing emissions of selected POPs. Continued monitoring is needed for these compounds, for which this is the first data available, provided by the WHO/UNEP survey in Morocco. [ABSTRACT FROM AUTHOR]

In the elections for the National Constituent Assembly, in December 1945, the port activist Juvenal Souto Júnior, candidate for the Communist Party of Brazil, was presented in the communist press as a "legitimate heir to the glorious traditions of struggle of the men and women of his race, the blacks of Bahia, who led or participated in the 1835 and subsequent movements against oppression and for the equal rights of colored workers". Juvenal was the second most voted candidate on the caption communist, surpassed only by Carlos Marighella, the only communist deputy elected by Bahia. In the post-Estado Novo period, many of the workers who stood out in the Bahian trade union movement were black. Some of these black workers saw in the short period of PCB legality (1945-1947) an important window of participation in party and electoral politics. Recent studies have focused on the PCB's relationship with the racial issue and black participation in party and electoral politics. However, these surveys have privileged the perspective of political partie and black activism and conjunctural variables, not devoting the same attention to the experiences and trajectories of workers and black union activists who had an effective role in party militancy and in the electoral dispute in the post-New State. This article departs from the perspective that the relationship of these black workers with party and electoral politics was a two-way street, where the speeches, guidelines and deliberations of the political party and black movements could be appropriated and re-meaning from of their trajectories and personal and social experiences. [ABSTRACT FROM AUTHOR]

As today the 137Cs fallout peak, in sediment cores, corresponds only to 25% of its initial concentration, alternatives to the use of 137Cs as a210Pb sediment dating validation tool are proposed. In highly industrialized bays, such as Guanabara Bay in the Rio de Janeiro metropolitan region, several chemical/compounds from the surrounding industry releases may be applied as validation tools. Chromium and copper profiles in a sediment core adequately fit the expected pattern due to the implementation of a chemical plant in 1958, reaching their maximum discharge in 1982 and subsequently decreasing due to the operation of a new wastewater treatment plant. A diffuse source such, as the PCB-based mixture Askarel, was also applied as an alternative validation tool, and the observed concentration profile reproduced the expected behavior, with increasing concentration after the Second World War and a decrease after the ban of this product in 1981. The observed Aroclor 1254 and 1260 mixture chlorination rates fit the most widely distributed PCB-based products in the country. • Alternatives for 210Pb sediment dating validation are suggested. • Chromium and zinc profile reflected the changes on a chemical industry. • PCB profile was compatible with the historical Askarel application in Brazil. [ABSTRACT FROM AUTHOR]

Electroless nickel (Ni) immersion gold (Au), commonly referred to by the acronym ENIG, is the most common protective coating applied on the exposed copper (Cu) traces of printed circuit boards (PCBs). In this work, we elucidate the local corrosion mechanism of the ENIG-Cu system by applying microscopic, surface analysis and electrochemical techniques with high spatial resolution to provide a comprehensive understanding of the complex local corrosion mechanism of the ENIG-Cu system. The corrosion initiation is highly localised and associated with pores or micro-defects in the Au layer. The corrosion initiates by the dissolution of the underlying Ni layer, being less noble than Au. The dissolution propagates in lateral and perpendicular directions relative to the surface in an elliptical fashion. With time, the direction of corrosion propagation changes to a predominantly lateral attack of the Ni layer. The corrosion process is governed by the cathode/anode ratio of the Au/Ni galvanic couple. [ABSTRACT FROM AUTHOR]

A method for the determination of four classes of potentially toxic substances (PTSs) was developed and applied in marine sediments, including (i) polycyclic aromatic hydrocarbons (PAHs), (ii) polychlorinated biphenyls (PCBs), (iii) polybrominated diphenyl ethers (PBDEs), and (iv) organochlorinated pesticides (OCPs). The method is based on ultrasonic extraction with a mixture of dichloromethane:methanol (9:1 v/v) and gas chromatography coupled with tandem mass spectrometry analysis (GC–MS/MS) in multiple reaction monitoring (MRM) mode. A total of 89 compounds were identified using two precursor-product ion standards for each analyte. The method detection limit (MDL; 0.001–0.055 ng g−1 dw) and method quantification limit (MQL; 0.002–0.184 ng g−1 dw) are below the usual thresholds of pollution adopted by international sediment quality guidelines. The method proved to be selective, sensitive, accurate, and linear, with the advantage of reducing sample handling time and consumable expenses (solvent, adsorbents). The developed method was successfully applied to surface sediments of Sepetiba Bay, Rio de Janeiro State, Brazil. Total concentrations of PAH (29.20–209.5 ng g−1 dw), PCB (0.06–2.16 ng g−1 dw), OCP (0.03–0.33 ng g−1 dw), and PBDE (0.06–0.21 ng g−1 dw) represent a baseline for these compounds and revealed mild to low levels of contamination in comparison to other coastal bays in SE Brazil. By using the proposed method, we expect this preliminary dataset can be expanded and include other similar coastal systems from developing countries marked by scarcity of information about levels, risk assessment, and specific sediment quality guidelines encompassing multiple classes of regulated and emerging organic contaminants. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to determine the spatial and temporal variations of polychlorinated biphenyl (PCB) levels in olive lands (0–5 cm) and to identify dominant PCB homologous groups and cancer risk values. In this context, surface soil samples were taken from seven olive lands in Bursa-Turkey for 9 months. Sampling points were categorized as rural, semi-rural, residential, and industrial areas. Regional-temporal trends of 43 PCB compounds were reported. The total average (∑43) PCB concentrations ranged between 8.3 ± 3.31 ng/g DM and 15.4 ± 3.3 ng/g DM. The lowest ∑43 PCB concentration was measured at the rural area (Mudanya Yörükali-MY) and the highest value was measured at Orhangazi Asilzade (OA), which is an industrial area. The dominant homologous group in all seasons was found to be 5-CBs (31%) followed by 4-CBs (16%) and 6-CBs (15%). Cancer risks were calculated and risk trend was determined as ingestion > dermal > inhalation. The values ranged between 5.26 × 10−6 and 1.28x10−5, 2.62 × 10−5 and 1.08x10−5, 1.68 × 10−1 and 6.9 × 10−12 for dermal, ingestion and inhalation, respectively. Also, the correlation between the levels of certain soil characteristics (dry matter, pH, and temperature) was also investigated. Statistical results showed that for PCB#89/101, PCB#135/144, PCB#126, PCB#156/171/202, PCB#172 PCB#170/190 it was determined that there was a significant relationship. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the level of some organic pollutants in the surface sediments of some dam lakes/ponds supplying drinking water to Tekirdağ, to specifiy possible PAH sources and to perform the ecological risk assessment of sediment quality. Sediment samples were taken from Naipköy Dam, Türkmenli Pond, Yazır Pond and Şarköy Pond in October, 2020. The concentrations of PAHs, PCBs and OCPs in the samples were measured using GC-MS/MS. Total PAH concentrations in the samples ranged from 20.56 ng/g (T5) to 124.4 ng/g (T4). When the samples are examined for individual PAH compounds, Naphthalene, Phenanthrene, Fluoranthene, Pyrene, Benzo(b)fluorantene, Chrysene and Fluorene are the predominant PAH compounds, respectively. Naphthalene is dominant in all other sediment samples, except for the T2 sediment sample, and its concentration has been detected in the range of 6.929 ng/g (T2) to 72.67 ng/g (T4). The total OCP concentrations ranged from 0.710 ng/g (T5) to 7.918 ng/g (T8), while the total PCB concentrations ranged from 0.120 ng/g (T5) to 0.383 (T8) ng/g. In the samples, the most dominant OCP compounds were DDT p, p, DDE p, p and HCH alpha, respectively, while PCB 153, 138 and 180 were the highest detected PCB congeners. Source identification of PAHs was made using the molecular ratios of PAH compounds. Considering all the calculated molecular ratios together, it has been found that the source of PAH compounds in sediment samples is mostly petrogenic. None of the levels of PAHs, PCBs and OCPs in the samples exceeded the ERM values, which is the contaminant level at which toxic effects often occur in aquatic organisms. [ABSTRACT FROM AUTHOR]

The paper proposed an alternative optical metrology to classical methods (strain gauge measurements and numerical simulation) for strain determination on printed circuit board (PCBs) due to thermal loads. The digital image correlation (DIC) technique was employed to record the strain distribution in some particular areas of the PCB. A thermal load was applied using a heating chamber, and the measurements were performed at four different temperature steps (25 °C, 50 °C, 85 °C and 120 °C). An increase in the principal strains with temperature was observed. For validation, the principal strains on the PCB obtained with DIC were compared with the values from gauge strain measurements and numerical simulation. The conclusions highlighted that DIC represents a technique with potential for strain measurement caused by thermal deformation, with the advantages of full field measurement, less preparation of the surface and good accuracy. [ABSTRACT FROM AUTHOR]

Non-coplanar polychlorinated biphenyl (PCB) mixture Aroclor 1254 and polybrominated diphenyl ether (PBDE) BDE-47 are known to impede neurogenesis and neuronal development. We previously reported that exposure to PCB and PBDE leads to increased embryonic movement in zebrafish by decreasing dopamine levels. In this study, we studied the connection between the melanin and dopamine synthesis pathways in this context. Both genetic and chemical inhibition of tyrosinase, the rate-limiting enzyme in melanin synthesis, not only led to reduced pigmentation but also inhibit PCB/PBDE-induced embryonic hyperactivity. Furthermore, PCB and PBDE rarely affected tyrosinase expression in the potential pigment cells, suggesting that these compounds reduce dopamine through enzymatic regulation, including a competitive interaction for the substrate tyrosine. Our results provide new insights into the interactions between melanogenesis and dopaminergic neuronal activity, which may contribute to understanding the mechanisms underlying PCB/PBDE toxicity in developing organisms. • Non-coplanar PCB and PBDE impede neurogenesis and neuronal development. • PCB and PBDE enhance embryonic movement in zebrafish by reducing dopamine levels. • Chemical and genetic inhibition of melanin synthesis reduced the PCB/PBDE-induced embryonic hyperactivity. • Our results revealed a link between melanin and dopamine synthesis at the neurobehavioral level. [ABSTRACT FROM AUTHOR]

Marine ecosystems face a significant ecological challenge due to the introduction and cycling of hazardous substances. The recent stabilization of concentrations of specific hazardous substances, which were previously decreasing, indicates significant ongoing processes within the ecosystem. These processes continue to make these substances available within the food chain, even following the implementation of restrictions and the elimination of known anthropogenic sources. The present study investigated the transfer of mercury, PBDEs, PCBs and their congeners via trophic transfer by combining consumer dietary characteristics and concentrations of these pollutants using European perch (Perca fluviatilis) and its prey as model organisms. The elevated concentrations of mercury and the accelerated trophic magnification in the perch population at one of the sampling sites appear to be linked to the selective consumption of Decapoda. However, the frequency of occurrence of any particular prey item in the perch diet does not account for the declining magnification slopes of PCBs at the site. Furthermore, in the distant sampling sites, PCBs and PBDEs do not exhibit consistent trophic magnification slopes. This suggests the significance of pollution loads in the neighboring water bodies and the migration patterns of the assessed species. • Uptake of hazardous substances can be influenced by the proportion and source of prey specific to the feeding ground. • High concentration levels were detected due to pollution pressures in closely located nursery grounds. • Elevated concentrations observed in predatory fish may not necessarily reflect higher pollution levels within the site. [ABSTRACT FROM AUTHOR]

A novel double-layer multiband, low-profile frequency selective surface (FSS) for IMT-Advanced (4G) mobile communication system is presented in this article. On aspired to a minimum transmission coefficient of -10 dB for surface materials when the frequency bands targeted for blocking are stopped. For this project, we chose the dielectric substrate FR4 (loss-tangent = 0.02; dielectric constant = 4.54) and a thickness of 1 mm. Dodecagonal rings, upright bars, and square frame make up the FSS unit cell. The desired frequency responses of the FSS were intended to avoid being changed according to the angle of incidence of the electromagnetic waves. The FSS design is proposed as a symmetrical structure to make it polarization-independent and is aimed to stop 800, 900, 1800, 2100, and 2600 MHz frequencies to prevent harmful effects to human health and interference effects at these frequencies. With a cell size of 0.17λ, the planned FSS is quite small and, thus, has a low sensitivity at the angle of the incident wave. In addition, FSS geometry was manufactured by a printed circuit board (PCB) and measured in a non-reflective environment after being studied in Ansys high-frequency structure simulator (HFSS) software. By comparing the analysis and measurement results of the design, the success of the FSS to the frequencies to be stopped has been verified. The effect of each patch on different frequencies has been examined by drawing the surface current density graphs of the design. [ABSTRACT FROM AUTHOR]

This paper discusses commonly used reverse engineering methods to illegally recreate printed circuit board (PCB) designs. A solution using transformative electronics is presented to prevent the discussed reverse engineering methods by obfuscating the design. The transformative electronics solution is employed in a specific application that results in a reverse engineered board to be incorrectly recreated, where the signals would be distorted due to added electromagnetic interference (EMI). The non-conductive vias that are part of the obfuscation would allow the inclusion of EMI generators that would not affect the circuit in an original design but would prevent copied designs from working correctly. A machine learning algorithm is being designed to optimize the placement of the EMI sources in an original PCB. [ABSTRACT FROM AUTHOR]

Dioxins compounds are persistent organic contaminants that adversely affect human health and the environmental system. Although the occurrence and toxicity of dioxins congeners are reported worldwide, their status in Iran is very scarce, and no study has been conducted to understand the evidence for occurrence and toxicity of dioxins compounds in Iran yet. Therefore, this systematic review provided a comprehensive report on the levels, occurrence, and health outcome effects of dioxins and dioxin-like Polychlorinated biphenyls (DL-PCBs) in foodstuffs collected from different cities of Iran. We used The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) to design this review, and six databases (Scopus, Scientific Information Database (SID), PubMed, Web of Knowledge, Scopus, and Google Scholar) were searched from inception until January 2022. A total of 9 articles with data on 396 food samples were considered for the final report. The total toxicity equivalency quantity (TEQ) was ranged from 0.06 ± 0.02 to 15.72 ±16.38 and the mean total dioxin congeners levels in most of the samples were below the standard limits and the measured intake levels of dioxin congeners were in the safe level. Although most of the samples did not exceed the maximum allowable thresholds, 44% of studies reported that the concentration of dioxin compounds in most of their samples was above the thresholds defined by world health organization (WHO) (3 pg TEQ/g fat). Therefore, suitable policy actions and more attention are needed to control and reduce the emission of dioxin congeners and their associated risk factors. [ABSTRACT FROM AUTHOR]

The article aims to analyze the debate on domestic work and rights for domestic workers promoted by women linked to the PCB between the 1940s and 1960s. Guided by demands made by working women themselves and by discussions that were being held internationally, the movement mobilized problematizations that went beyond the world of work and the legal sphere insofar as it denatured rooted ideas that domestic work and the management of family daily life were "women's things". In this sense, he thought of alternatives to "free" women from what he called "domestic slavery". [ABSTRACT FROM AUTHOR]

In 1947, in municipal elections, three communist women were elected councillors of the Federal District, Rio de Janeiro. They were Arcelina Mochel, Lia Corrêa Dutra and Odila Schmidt. The purpose of this article is to analyze their profile and political performance during the short period of time in which the Brazilian Communist Party (PCB) was legal (1946-1948). From the perspectives of women's history, gender relations and social history, the aim is to understand how these activists built an agenda of specific demands for women within the political party struggle. Thus highlighting the importance of the discussion about motherhood, domestic work, family care, equal pay, labor laws, among other topics. By analyzing the daily political life of the councillors in the Town Council, the article shows how they created strategies to address these issues inside and outside the Party and parliament, boosting the organization of women in the peripheral regions of the former federal capital. Based on the analysis of the Momento Feminino periodical and the documentation of the political police of Rio de Janeiro, we argue that the relatively democratic environment made possible by the fall of the Estado Novo dictatorship (1937-1945), the end of the Second World War and the 1946 Constituent Assembly, opened paths for the participation of women in politics, especially the female leaders of the PCB. In addition, we show how the communists, although influenced by Stalinist social policy, formulated women's demands in line with the ongoing labor policy in the 1940s. [ABSTRACT FROM AUTHOR]

This text offers a reflection about the treatment that the PCB - the oldest political party in Brazil - the attention given to the race issue in first decades of existence, mainly in the 1920s and 1930s. Using bibliographic sources, official documents and press articles linked to the party we conclude that: if on the one side, the PCB did not ignore the Brazilian racial issue, on the other, it dealt with it laterally in its documents and institutional action, largely due to the assimilation of the thesis that the uniqueness of Brazilian social and historical development would determine a type of sociability in which the modernization of society would make possible the overcome racism, for this very reason, issues related to social classes would overlap the Brazilian racial issue, even when amalgamated. [ABSTRACT FROM AUTHOR]

This research investigates sorption of PCBs to fabrics in a contaminated indoor environment and the effect of laundering on PCB removal from the fabrics. Eight articles of clothing were exposed to the air in a PCB‐contaminated building. The background air concentration was 670 ng/m3 PCBtotal with PCB‐52 being the main congener. Air and fabric samples were collected for analysis before and periodically throughout the experiment. After 25 weeks, the remaining fabrics were washed and cut into three pieces each. One part was dried in the contaminated building, second in a PCB‐free building and third in a mechanical drier. The PCB mass concentration increased during the first 6–10 weeks for all investigated fabrics, after which some fabrics approached equilibrium for more volatile congeners. Mass‐normalized cloth‐air partition coefficients were quantified for 9 congeners; for PCB‐52, these ranged from 106.1 to 107.0 which were consistent with previously reported values. Partition coefficients of PCBs were observed to increase with their respective octanol‐air partition coefficients. Washing and drying clothes resulted in the removal between 22% and 84% of PCBs. There was no difference in removal percentage after air‐drying in clean or contaminated air. Drying in a mechanical drier removed significantly more PCBs than air‐drying. [ABSTRACT FROM AUTHOR]

The continuous drop out of participants in longitudinal studies is a trend that may be observed in nearly all fields of medical research. A reduced participation rate might compromise the power of statistical analysis as well as lead to an attrition bias of the study. The aim of this analysis was to identify influencing factors on participation frequency in the monitoring program Health Effects in High Level Exposure to polychlorinated biphenyls (HELPcB) study, a cohort investigation of occupationally polychlorinated biphenyls (PCB) exposed individuals. The HELPcB study was initiated in 2010 and consisted of 7 study visits. At the last cross-section in 2019, less than one third of the included patients still actively participated. As possible influencing factors on study participation frequency, demographic, social, and medical characteristics of the participants were examined. In addition, a logistic regression model to predict study participation behavior was calculated. An overall higher frequency of participation was observed, if participants joined the program together with relatives or friends and had a higher age. For PCB plasma levels, an exceedance of the biological reference value (BAR) and further factors, such as (1) professional qualification, (2) later inclusion, (3) type of participant and (4) occupational-related disease notification, significant differences in the participation frequency were observed in the univariate analysis. Only age and joined study participation remained significant in the multivariate logistic regression. In conclusion, it was possible to identify several social and occupational-related factors that influence the frequency of participation of study attendees. [ABSTRACT FROM AUTHOR]

Shredded dust originated during mechanical dismantling of waste electrical and electronic equipments (WEEEs) is enriched source of some valuable metals which might be lost as unworthy waste. Composition analysis of shredded dust printed circuit boards (PCBs) revealed the presence of 12.75 mg g−1 copper (Cu) and 10.34 mg g−1 silver (Ag) along with some other metals (Fe, Ni, and Au). Low concentration of precious metal, such as gold (Au i.e., 0.04 mg g−1) classified this shredded dust as low-grade scrap. Despite low concentration of Au this e-waste can be considered as potential "secondary ore" to recover other valuable metals like Ag. To improve the efficiency of Ag bioleaching using Pseudomonas balearica SAE1, pretreatment of e-waste was done using cost-effective ferric chloride (FeCl3) chemical lixiviant. The concentration of FeCl3 lixiviant was optimized to recover Cu metal prior to bioleaching process. Bioleaching of Ag was done under optimized conditions by Pseudomonas balearica SAE1 using 100 mL Luria Broth (LB) medium, 5 g L−1 glycine, pH 9, temperature 30 °C and 150 rpm. 95% Cu was recovered with 1% FeCl3 prior to bioleaching. Ag solubilization was increased for treated e-waste (36%) as compared to untreated e-waste PCBs (25%). Prerecovery of Cu enhanced Ag bioleaching, as available cyanide was utilized by Ag metal. Therefore, this study provides an economical hybrid method to enhance retrieval of precious metal (Ag) by Pseudomonas balearica SAE1 with economic and ecofriendly redox lixiviant even from low-grade e-scrap. [ABSTRACT FROM AUTHOR]

Future cellular communication systems might be based on millimeter wave frequencies. So, there is a need to design and deploy antennas which operate in the millimeter wave spectrum integrated in mobile terminals, portable wireless devices, base stations and access points. Even though a lot of articles exist on the design of such antennas, fabrication and measurement nuances of such antennas are addressed rarely in the open literature. Initially, the fabrication process of printed circuit board (PCB) antennas is discussed in detail with sources of error and possible precautions. A case study of microstrip-based tapered slot antenna operating at 28 GHz is presented. The variations in the antenna characteristics with slight variations due to fabrication errors are presented. A detailed discussion on S-parameters, pattern and gain measurements is also presented along with possible sources of errors associated with them. [ABSTRACT FROM AUTHOR]

Shredded dust originated during mechanical dismantling of waste electrical and electronic equipments (WEEEs) is enriched source of some valuable metals which might be lost as unworthy waste. Composition analysis of shredded dust printed circuit boards (PCBs) revealed the presence of 12.75 mg g−1 copper (Cu) and 10.34 mg g−1 silver (Ag) along with some other metals (Fe, Ni, and Au). Low concentration of precious metal, such as gold (Au i.e., 0.04 mg g−1) classified this shredded dust as low-grade scrap. Despite low concentration of Au this e-waste can be considered as potential "secondary ore" to recover other valuable metals like Ag. To improve the efficiency of Ag bioleaching using Pseudomonas balearica SAE1, pretreatment of e-waste was done using cost-effective ferric chloride (FeCl3) chemical lixiviant. The concentration of FeCl3 lixiviant was optimized to recover Cu metal prior to bioleaching process. Bioleaching of Ag was done under optimized conditions by Pseudomonas balearica SAE1 using 100 mL Luria Broth (LB) medium, 5 g L−1 glycine, pH 9, temperature 30 °C and 150 rpm. 95% Cu was recovered with 1% FeCl3 prior to bioleaching. Ag solubilization was increased for treated e-waste (36%) as compared to untreated e-waste PCBs (25%). Prerecovery of Cu enhanced Ag bioleaching, as available cyanide was utilized by Ag metal. Therefore, this study provides an economical hybrid method to enhance retrieval of precious metal (Ag) by Pseudomonas balearica SAE1 with economic and ecofriendly redox lixiviant even from low-grade e-scrap. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with severe effects on human health and the biosphere. Plant-based remediation offersmany benefits over conventional PCB remediation, but its development has been hampered by our poor understanding of biphenyl metabolism in eukaryotes, among other factors. We report here a major PCB-responsive protein in poplar, a plant model system capable of PCB uptake and translocation. We provide structural and functional evidence that this uncharacterized protein, termed SDR57C, belongs to the heterogeneous short-chain dehydrogenase reductase (SDR) superfamily. Despite sequence divergence, structural modeling hinted at structural and functional similarities between SDR57C and BphB, a central component of the Bph pathway for biphenyl/PCB degradation in aerobic bacteria. By combining gas chromatography/mass spectrometry (GC/MS) profiling with a functional complementation scheme, we found that poplar SDR57C can replace BphB activity in the upper Bph pathway of Pseudomonas furukawaii KF707 and therefore catalyze the oxidation of 2,3-dihydro-2,3-dihydroxybiphenyl (2,3-DHDB) to 2,3-dihydroxybiphenyl (2,3-DHB). Consistent with this biochemical activity, we propose a mechanism of action based on prior quantum studies, general properties of SDR enzymes, and the modeled docking of 2,3-DHDB to the SDR57C-NAD+ complex. The putative detoxifying capacity of SDR57C was substantiated through reverse genetics in Arabidopsis thaliana. Phenotypic characterization of the SDR lines underscored an inducible plant pathway with the potential to catabolize toxic biphenyl derivatives. Partial similarities with aerobic bacterial degradation notwithstanding, real-time messenger RNA quantification indicates the occurrence of plant-specific enzymes and features. Our results may help explain differences in degradative abilities among plant genotypes and also provide elements to improve them. [ABSTRACT FROM AUTHOR]

Greenhouse assessment of the effect of oil on Chromolaena odorata ability to remove PCB from soil treated with transformer oil co-contaminated with Aroclor 1260 was done. Plants were transplanted into one kilogram of soil contained in 1 L pots differently containing 100, 200, and 500 ml of transformer oil (T/O), co-contaminated with 100 ppm of Aroclor. Treatments were done in two microcosms; direct contamination and soil cultured method. Measured plant growth parameters showed that C. odorata growth was affected by the different concentrations of oil. Inhibition of plant growth by oil increased with concentrations. At the end of six weeks, plant growth was affected in T/O amended soil. Plants size was increased by 1.4, 0.46 and −1.0% in direct treatment and 17.01, 6.09 and 1.08% in soil culture at the 100, 200 and 500 ppm respectively. Untreated control showed a 43.07% increase. Slight PCB recovery was observed in root tissues of C. odorata but soil PCB was reduced by 66.6, 53.2, 41.5% and 77.3, 74.7, 58.8% at both treatments in their respective concentrations of oil. However, unplanted control was reduced by 21.4 and 16.7% in the two treatments at 66,000 ppm of oil. This study has shown that with improved agronomic practices, there is a possibility of phytoremediation of soil PCB from PCB contained transformer oil contaminated soil using Chromolaena odorata, hence it should be optimized in the field. [ABSTRACT FROM AUTHOR]