Bimetallic catalyst system for the degradation of PCBs in sediments.

In this paper, we report the successful application of a patent-pending reduced bimetallic nanoparticle catalytic system developed for the remediation of polychlorinated biphenyl (PCB)-contaminated sediment and aquatic media. The formation of bimetallic nanoparticles associated with the granular activated carbon (GAC) were confirmed by high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy showed the presence of the bimetallic matrix in reduced, albeit mixed, states. In the degradation studies, the bimetallic nanoparticles were deposited on a GAC substrate and utilized to treat both a surrogate PCB, 2-Chlorobiphenyl (2-CBP) in water and contaminated bottom-river sediments collected from a site with mixed-congener PCB contamination. The degradation studies on non-degassed water contaminated with 2-CBP at room temperature showed a high yield of 2-CBP degradation to biphenyl and phenol. Results from the bottom-river sediments contaminated with PCBs (tested in laboratory environment at ambient temperature and atmospheric conditions, not degassed) have indicated the bimetallic catalyst has great promise for remedial application in sediment and aquatic media. Results illustrate that this newly-developed and patent-pending catalytic system degrades PCBs through stepwise dichlorination, with expected byproducts such as biphenyl and phenol leading to mineralization of the PCBs.

Comprehensive Compilation of Congener Profiles to Support Health Assessment of Environmental Exposures to Polychlorinated Biphenyl Mixtures.

Exposure to polychlorinated biphenyls (PCBs) remains a potential human health risk due to their persistence in the environment, despite a global ban on their production. Understanding the composition of PCB mixtures is essential for the application of a mixtures-based approach to assessing health risks of PCB exposure. This work represents the most extensive effort to date to compile and make publicly available the PCB congener profiles for mixtures with toxicological data, providing a foundation for understanding toxicological potency of PCB mixtures in the environment. We identified published congener profiles across 29 commercial and simulated environmental PCB mixtures, including various Aroclors, Phenoclors, Clophens, and Kanechlors, among others. A total of 117 references containing 401 distinct complete or partial tabularized profiles were found. Aroclor 1254 had the most published profiles, with 79 unique datasets characterizing multiple mixture lots. In contrast, no congener-specific composition data were identified for Fenclors, Clophen C, or Pyralenes. Eighty-seven of the most complete and clearly reported profiles underwent a detailed extraction of the congener data, PCB mixture source, and analytical methods. Challenges encountered during data extraction included congener coelutions, incomplete methods reporting, and inconsistencies in PCB nomenclature. These factors complicate data visualization, comparisons across datasets, and use of the data in subsequent analyses. Where possible, we have converted profiles to the same units and congener numbering convention to allow for easier comparison. The extracted data are publicly available online as interactive visuals and as a downloadable Microsoft Excel® workbook. This dataset provides researchers with an overview of the current PCB mixture profile landscape that can serve as a tool to support efforts to minimize the health impacts of environmental PCB exposure, including the exploration of links between mixture composition and toxicity and the identification of the most efficient and effective remediation strategies at contaminated sites.

YOLO-BFRV: An Efficient Model for Detecting Printed Circuit Board Defects.

The small area of a printed circuit board (PCB) results in densely distributed defects, leading to a lower detection accuracy, which subsequently impacts the safety and stability of the circuit board. This paper proposes a new YOLO-BFRV network model based on the improved YOLOv8 framework to identify PCB defects more efficiently and accurately. First, a bidirectional feature pyramid network (BIFPN) is introduced to expand the receptive field of each feature level and enrich the semantic information to improve the feature extraction capability. Second, the YOLOv8 backbone network is refined into a lightweight FasterNet network, reducing the computational load while improving the detection accuracy of minor defects. Subsequently, the high-speed re-parameterized detection head (RepHead) reduces inference complexity and boosts the detection speed without compromising accuracy. Finally, the VarifocalLoss is employed to enhance the detection accuracy for densely distributed PCB defects. The experimental results demonstrate that the improved model increases the mAP by 4.12% compared to the benchmark YOLOv8s model, boosts the detection speed by 45.89%, and reduces the GFLOPs by 82.53%, further confirming the superiority of the algorithm presented in this paper.

Impacts on Atlantic Killifish from Neurotoxicants: Genes, Behavior, and Population-Relevant Outcomes.

Molecular, cellular, and organismal alterations are important descriptors of toxic effects, but our ability to extrapolate and predict ecological risks is limited by the availability of studies that link measurable end points to adverse population relevant outcomes such as cohort survival and growth. In this study, we used laboratory gene expression and behavior data from two populations of Atlantic killifish Fundulus heteroclitus [one reference site (SCOKF) and one PCB-contaminated site (NBHKF)] to inform individual-based models simulating cohort growth and survival from embryonic exposures to environmentally relevant concentrations of neurotoxicants. Methylmercury exposed SCOKF exhibited brain gene expression changes in the si:ch211-186j3.6, si:dkey-21c1.4, scamp1, and klhl6 genes, which coincided with changes in feeding and swimming behaviors, but our models simulated no growth or survival effects of exposures. PCB126-exposed SCOKF had lower physical activity levels coinciding with a general upregulation in nucleic and cellular brain gene sets (BGS) and downregulation in signaling, nucleic, and cellular BGS. The NBHKF, known to be tolerant to PCBs, had altered swimming behaviors that coincided with 98% fewer altered BGS. Our models simulated PCB126 decreased growth in SCOKF and survival in SCOKF and NBHKF. Overall, our study provides a unique demonstration linking molecular and behavioral data to develop quantitative, testable predictions of ecological risk.

Significant metabolic alterations in mouse dams exposed to an environmental mixture of polychlorinated biphenyls (PCBs) during gestation and lactation: Insights into PCB and metabolite profiles.

Polychlorinated biphenyls (PCBs) and their metabolites are linked to developmental neurotoxicity, but their levels in the gestational and lactational environment remain unexplored. This study investigated the effects of dietary exposure to the Fox River Mixture (FRM) on serum levels of PCBs and their metabolites in female C57BL/6 J mice. Mice were exposed to 0.1, 1.0, or 6.0 mg/kg body weight/day of FRM beginning two weeks before mating and throughout gestation and lactation. Serum samples collected from the dams at weaning were analyzed using gas chromatograph-tandem mass spectrometry and nontarget liquid chromatography-high resolution mass spectrometry. Results showed complex and dose-dependent differences in PCB and metabolite profiles. Untargeted metabolomics revealed alterations in metabolites involved in glucuronidation. Network analysis suggested disturbances in heme and amino acid metabolism associated with higher chlorinated PCBs. These findings suggested that PCBs and metabolites present in the gestational and lactation environment of mice may contribute to developmental neurotoxicity in rodents.

Dioxins, PFOS, and 20 other Persistent Organic Pollutants in Eggs of Nine Wild Bird Species from the Vaal River, South Africa.

The Vaal River catchment drains the largest and most populated industrial and mining region in Southern Africa. Heron, ibis, cormorant, egrets, and darter eggs, representing three habitats and four feeding guilds, were collected at four locations in 2009/10 to identify hotspots and hazards associated with persistent organic pollutants (POPs). The POPs included 21 organochlorine pesticides, five polybrominated diphenyl ether (PBDE) classes, 18 polychlorinated biphenyls (PCBs including six non-dioxin-like PCBs; NDL-PCB), and 12 dioxin-like PCBs (DL-PCBs), 17 polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDD/Fs), and perfluorooctane sulfonate (PFOS). Aquatic predators had higher PFOS and PCDD/F concentrations, while PCBs dominated in terrestrial eggs. Organochlorine pesticides, PBDEs, and PCBs were strongly associated with eggs from the industrial regions, while PCDD/F concentrations were evenly distributed. PCDD/F and PCB toxic equivalency quotient concentrations were low with no adverse effects expected. PFOS peaked at Bloemhof Dam with a maximum of 2300 ng/g wm in an African Darter egg, indicating an unexpected PFOS hotspot, the source of which is unknown. Despite order of differences in compound class concentrations, there was no association with egg size. To the best of our knowledge, this is the only study that analysed all 2010 POPs in bird eggs on a large geographic scale. This study highlighted the importance of multi-species studies sampling from multiple locations to assess the risk that POPs pose to avian populations as hotspots and species at risk may be missed by studies looking at one or few species.

Polychlorinated Biphenyls (PCBS)-induced oxidative stress and inflammation in human thyrocytes: involvement of AhR and NRF-2/HO-1 pathway.

PURPOSE: In this in vitro study, we investigated the effects of polychlorinated biphenyls (PCBs) on human thyrocytes, with a focus on the involvement of AhR, a key player in xenobiotic response, and the anti-oxidant Nrf-2/HO-1 pathway. METHODS: Primary cultured thyrocytes were exposed to the dioxin-like congeners PCB118 and PCB126 at 2.5 and 5 µM concentrations. mRNA expression was assessed by real-time PCR, and protein expression by Western Blot and ELISA, while protein quantification was assessed by densitometric analysis. RESULTS: In cultured thyrocytes, PCB118 and PCB126 induced a significant (P < 0.01) increase of mRNA and protein levels of the pro-inflammatory cytokines IL-1beta and IL-6, while reducing those of thyroglobulin (TG) and NIS (p < 0.05), indicating down-regulation of these thyroid-specific genes in PCB-induced inflammation. ROS production also increased (p < 0.001). mRNA levels of AhR and the downstream molecules cytochrome P4501A, Nrf-2/HO-1 increased (p < 0.001), as well as related protein levels (p < 0.01), suggesting the activation of AhR and Nrf-2 pathways in response to PCBs exposure. AhR silencing decreased AhR-related gene expression and restored NIS and TG expression, while reducing inflammatory cytokines and oxidative stress markers (p < 0.05). CONCLUSIONS: Dioxin-like PCBs (PCB118 and PCB126) may promote inflammation and oxidative stress in thyrocytes, impairing the expression of genes that are key players of thyroid function. These effects can be partially attributed to the activation of the AhR and Nrf-2 pathways. These data may contribute to explain the mechanisms underlying thyroid toxicity of PCBs, highlighting the potential role of these pollutants as a trigger of autoimmune thyroid inflammation and damage.

PCB plug-in solder joint defect detection method based on coordinated attention-guided information fusion.

Printed Circuit Boards (PCBs) are the foundational component of electronic devices, and the detection of PCB defects is essential for ensuring the quality control of electronic products. Aiming at the problem that the existing PCB plug-in solder defect detection algorithms cannot meet the requirements of high precision, low false alarm rate, and high speed at the same time, this paper proposes a method based on spatial convolution pooling and information fusion. Firstly, on the basis of YOLOv3, an attention-guided pyramid structure is used to fuse context information, and multiple convolutions of different size are used to explore richer high-level semantic information; Secondly, a coordinated attention network structure is introduced to calibrate the fused pyramidal feature information, highlighting the important feature channels, and reducing the adverse impact of redundant parameters generated by feature fusion; Finally, the ASPP (Atrous Spatial Pyramid Pooling) structure is implemented in the original Darknet53 backbone feature extraction network to acquire multi-scale feature information of the detection targets. With these improvements, the average detection accuracy of the enhanced network has been elevated from 94.45 to 96.43%. This experiments shows that the improved network is more suitable for PCB plug-in solder defect detection applications.

Identifying Universal Fish Biomarker Genes in Response to PCB126 Exposure by Comparative Transcriptomic Analyses.

Water pollution remains a major environmental concern, with increased toxic by-products being released into water bodies. Many of these chemical contaminants persist in the environment and bio-accumulate in aquatic organisms. At present, toxicological tests are mostly based on laboratory tests, and effective methods for monitoring wild aquatic environments remain lacking. In the present study, we used a well-characterized toxic chemical, 3,3',4,4',5-polychlorinated biphenyl (PCB126), as an example to try to identify common biomarker genes to be used for predictive toxicity of this toxic substance. First, we used two laboratory fish models, the zebrafish (Danio rerio) and medaka (Oryzias latipes), to expose PCB126 to obtain liver transcriptomic data by RNA-seq. Comparative transcriptomic analyses indicated generally conserved and concerted changes from the two species, thus validating the transcriptomic data for biomarker gene selection. Based on the common up- and downregulated genes in the two species, we selected nine biomarker genes to further test in other fish species. The first validation experiment was carried out using the third fish species, Mozambique tilapia (Oreochromis mossambicus), and essentially, all these biomarker genes were validated for consistent responses with the two laboratory fish models. Finally, to develop universal PCR primers suitable for potentially all teleost fish species, we designed degenerate primers and tested them in the three fish species as well as in another fish species without a genomic sequence available: guppy (Poecilia reticulata). We found all the biomarker genes showed consistent response to PCB126 exposure in at least 50% of the species. Thus, our study provides a promising strategy to identify common biomarker genes to be used for teleost fish analyses. By using degenerate PCR primers and analyzing multiple biomarker genes, it is possible to develop diagnostic PCR arrays to predict water contamination from any wild fish species sampled in different water bodies.

Design and Analysis of Receiver Coils with Multiple In-Series Windings for Inductive Eddy Current Angle Position Sensors Based on Coupling of Coils on Printed Circuit Boards.

We present a method for improving the amplitude and angular error of inductive position sensors, by advancing the design of receiver coil systems with multiple windings on two layers of a printed circuit board. Multiple phase-shifted windings are connected in series, resulting in an increased amplitude of the induced voltage while decreasing the angular error of the sensor. The amplitude increase for a specific number of windings can be predicted in closed form. Windings are placed electrically in series by means of a differential connection structure, without adversely affecting the signal quality while requiring a minimal amount of space in the layout. Further, we introduce a receiver coil centerline function which specifically enables dense, space-constrained designs. It allows for maximization of the number of possible coil windings while minimizing the impact on angular error. This compromise can be fine-tuned freely with a shape parameter. The application to a typical rotary encoder design for motor control applications with five periods is presented as an example and analyzed in detail by 3D finite-element simulation of 18 different variants, varying both the number of windings and the type of centerline functions. The best peak-to-peak angular error achieved in the examples is smaller than 0.1° electrically (0.02° mechanically, periodicity 5) under nominal tolerance conditions, in addition to an amplitude increase of more than 170% compared to a conventional design which exhibits more than twice the angular error. Amplitude gains of more than 270% are achieved at the expense of increased angular error.

Upregulation of fatty acid synthesis genes in the livers of adolescent female rats caused by inhalation exposure to PCB52 (2,2',5,5'-Tetrachlorobiphenyl).

Elevated airborne PCB levels in older schools are concerning due to their health impacts, including cancer, metabolic dysfunction-associated steatotic liver disease (MASLD), cardiovascular issues, neurodevelopmental diseases, and diabetes. During a four-week inhalation exposure to PCB52, an air pollutant commonly found in school environments, adolescent rats exhibited notable presence of PCB52 and its hydroxylated forms in their livers, alongside changes in gene expression. Female rats exhibited more pronounced changes in gene expression compared to males, particularly in fatty acid synthesis genes regulated by the transcription factor SREBP1. In vitro studies with human liver cells showed that the hydroxylated metabolite of PCB52, 4-OH-PCB52, but not the parent compound, upregulated genes involved in fatty acid biosynthesis similar to in vivo exposure. These findings highlight the sex-specific effects of PCB52 exposure on livers, particularly in females, suggesting a potential pathway for increased MASLD susceptibility.

EC-YOLO: Improved YOLOv7 Model for PCB Electronic Component Detection.

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.

Persistent and Bioaccumulative Halogenated Natural Products in Various Tropical Reef Fish Species from the Seychelles, Western Indian Ocean.

Gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) was used to quantify and compare halogenated natural products (HNPs) and selected anthropogenic persistent organic pollutants (POPs) in individual samples of 17 fish species from the Seychelles (Western Indian Ocean). The sum-HNP amounts (9.5-1100 ng/g lipid mass (lm)) were between 1 and 2 orders of magnitude higher than those of the sum of seven abundant polychlorinated biphenyl (PCB) congeners (0.2-15 ng/g lm) and dichlorodiphenyltrichloroethane-related compounds (DDTs) (<1.1-43 ng/g lm). Within the group of HNPs, the two tetrabrominated phenoxyanisoles (aka methoxylated diphenyl ethers, MeO-BDEs), 2'-MeO-BDE 68 ≫ 6-MeO-BDE 47, were predominant in most cases. Pearson correlation analysis showed that MeO-BDE levels were positively correlated with less abundant HNPs (2,2'-diMeO-BB 80, 2',6-diMeO-BDE 68, and Br6-DBP) (p < 0.01). Accordingly, HNPs, rather than PCBs and DDTs, were the predominant polyhalogenated contaminants in the current species.

Astrocyte Mitochondria Are a Sensitive Target of PCB52 and its Human-Relevant Metabolites.

Polychlorinated biphenyls (PCBs) are industrial chemicals that are ubiquitously found in the environment. Exposure to these compounds has been associated with neurotoxic outcomes; however, the underlying mechanisms for such outcomes remain to be fully understood. Recent studies have shown that astrocytes, the most abundant glial cell type in the brain, are susceptible to PCB exposure as well as exposure to human-relevant metabolites of PCBs. Astrocytes are critical for maintaining healthy brain function due to their unique functional attributes and positioning within the neuronal networks in the brain. In this study, we assessed the toxicity of PCB52, one of the most abundantly found PCB congeners in outdoor and indoor air, and two of its human-relevant metabolites, on astrocyte mitochondria. We exposed C6 cells, an astrocyte cell line, to PCB52 or its human-relevant metabolites and found that all the compounds showed increased toxicity in galactose-containing media compared to that in the glucose-containing media, indicating the involvement of mitochondria in observed toxicity. Additionally, we also found increased oxidative stress upon exposure to PCB52 metabolites. All three compounds caused a loss of mitochondrial membrane potential, distinct changes in the mitochondrial structure, and impaired mitochondrial function. The hydroxylated metabolite 4-OH-PCB52 likely functions as an uncoupler of mitochondria. This is the first study to report the adverse effects of exposure to PCB52 and its human-relevant metabolites on the mitochondrial structure and function in astrocytes.

Alternatives to 137Cs for 210Pb dating validation in south America and in the Carribean region: Point and diffuse sources.

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.

Tyrosinase inhibition prevents non-coplanar polychlorinated biphenyls and polybrominated diphenyl ethers-induced hyperactivity in developing zebrafish: Interaction between pigmentation and neurobehavior.

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.

Robotont 3-an accessible 3D-printable ROS-supported open-source mobile robot for education and research.

Educational robots offer a platform for training aspiring engineers and building trust in technology that is envisioned to shape how we work and live. In education, accessibility and modularity are significant in the choice of such a technological platform. In order to foster continuous development of the robots as well as to improve student engagement in the design and fabrication process, safe production methods with low accessibility barriers should be chosen. In this paper, we present Robotont 3, an open-source mobile robot that leverages Fused Deposition Modeling (FDM) 3D-printing for manufacturing the chassis and a single dedicated system board that can be ordered from online printed circuit board (PCB) assembly services. To promote accessibility, the project follows open hardware practices, such as design transparency, permissive licensing, accessibility in manufacturing methods, and comprehensive documentation. Semantic Versioning was incorporated to improve maintainability in development. Compared to the earlier versions, Robotont 3 maintains all the technical capabilities, while featuring an improved hardware setup to enhance the ease of fabrication and assembly, and modularity. The improvements increase the accessibility, scalability and flexibility of the platform in an educational setting.

Implementation of microcontroller board on a sustainable and degradable PLA/flax composite substrate: a case study.

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.

Local and Global Context-Enhanced Lightweight CenterNet for PCB Surface Defect Detection.

Printed circuit board (PCB) surface defect detection is an essential part of the PCB manufacturing process. Currently, advanced CCD or CMOS sensors can capture high-resolution PCB images. However, the existing computer vision approaches for PCB surface defect detection require high computing effort, leading to insufficient efficiency. To this end, this article proposes a local and global context-enhanced lightweight CenterNet (LGCL-CenterNet) to detect PCB surface defects in real time. Specifically, we propose a two-branch lightweight vision transformer module with local and global attention, named LGT, as a complement to extract high-dimension features and leverage context-aware local enhancement after the backbone network. In the local branch, we utilize coordinate attention to aggregate more powerful features of PCB defects with different shapes. In the global branch, Bi-Level Routing Attention with pooling is used to capture long-distance pixel interactions with limited computational cost. Furthermore, a Path Aggregation Network (PANet) feature fusion structure is incorporated to mitigate the loss of shallow features caused by the increase in model depth. Then, we design a lightweight prediction head by using depthwise separable convolutions, which further compresses the computational complexity and parameters while maintaining the detection capability of the model. In the experiment, the LGCL-CenterNet increased the mAP@0.5 by 2% and 1.4%, respectively, in comparison to CenterNet-ResNet18 and YOLOv8s. Meanwhile, our approach requires fewer model parameters (0.542M) than existing techniques. The results show that the proposed method improves both detection accuracy and inference speed and indicate that the LGCL-CenterNet has better real-time performance and robustness.

Real-time H 2 S detection kit for hydrogen fuel cell.

Among hydrogen technologies, a proton exchange membrane fuel cell (PEMFC) is known as an efficient device using hydrogen as the fuel. Although different real-time fault-diagnosis methods are available (i.e., voltage-based or electrochemical-based), the problem with these methods is their dependency on being directly connected to a computer, higher costs, lower security, and the need to perform the tests in a laboratory. The focus and the solution of this study are to propose a novel design of printed circuit board (PCB) that enables the implementation of the required sensors to detect/measure the operational parameters/contamination of PEMFC. The communication of the considered PCB will be with a server without direct contact through the Internet of Things (IoT). A specified computer. exe file has also been developed to directly connect to a personalized network hotspot (to increase security) and enable the wireless communication of the sensor and the computer. The outputs of this study can be considered a novel fault diagnosis kit that measures H 2 S wirelessly using IoT. To verify the result 11 ppm and 12 ppm of H 2 S was injected into the system, the IoT kit's measured data is compared with the experiments. The results comparison validated the suitability of the system.