Liquid Metal Embrittlement Cracking in Uncoated Transformation-Induced Plasticity Steel during Consecutive Resistance Spot Welding

In the automotive production line, a single pair of electrodes is employed to produce hundreds of consecutive welds before undergoing dressing or replacement. In consecutive resistance spot welding (RSW) involving Zn-coated steels, the electrodes undergo metallurgical degradation, characterized by Cu-Zn alloying, which impacts the susceptibility to liquid metal embrittlement (LME) cracking. In the present investigation, the possibility of LME crack formation in uncoated TRIP steel joints during consecutive RSW (involving 400 welds in galvannealed and uncoated TRIP steels) was investigated. The results have shown that different Cu-Zn phases were formed on the electrode surface because of its contamination with Zn from the galvannealed coating. Therefore, during the welding of the uncoated TRIP steel, the heat generated at the electrode/sheet interface would result in the melting of the Cu-Zn phases, thereby exposing the uncoated steel surface to molten Zn and Cu, leading to LME cracking. The cracks exhibited a maximum length of approximately 30 µm at Location A (weld center) and 50 µm at Location B (shoulder of the weld). The occurrence and characteristics of the cracks differed depending on the location as the number of welds increased due to the variation in Zn content. Type A cracks did not form when the number of welds was less than 280. Several cracks with a total length of approximately 30 μm were suddenly formed between 280 and 400 welds. On the other hand, type B cracks began to appear after 40 welds. However, the number and size of these exhibited inconsistency as the number of welds increased. Overall, the results have shown that small LME cracks can form even in uncoated steels during consecutive welding of Zn-coated and uncoated steel joints

Rabies control in Bangladesh and prediction of human rabies cases by 2030: a One Health approach

Background Bangladesh is making progress toward achieving zero dog-mediated rabies deaths by 2030, a global goal set in 2015. Methods Drawing from multiple datasets, including patient immunisation record books and mass dog vaccination (MDV) databases, we conducted a comprehensive analysis between 2011 and 2023 to understand the effectiveness of rabies control programmes and predict human rabies cases in Bangladesh by 2030 using time-series forecasting models. We also compared rabies virus sequences from GenBank in Bangladesh and other South Asian countries. Findings The estimated dog population in Bangladesh was determined to be 1,668,140, with an average dog population density of 12.83 dogs/km2 (95% CI 11.14–14.53) and a human-to-dog ratio of 86.70 (95% CI 76.60–96.80). The MDV campaign has led to the vaccination of an average of 21,295 dogs (95% CI 18,654–23,935) per district annually out of an estimated 26,065 dogs (95% CI 22,898–29,230). A declining trend in predicted and observed human rabies cases has been identified, suggesting that Bangladesh is poised to make substantial progress towards achieving the ‘Zero by 30’ goal, provided the current trajectory continues. The phylogenetic analysis shows that rabies viruses in Bangladesh belong to the Arctic-like-1 group, which differs from those in Bhutan despite sharing a common ancestor. Interpretation Bangladesh's One Health approach demonstrated that an increase in MDV and anti-rabies vaccine (ARV) resulted in a decline in the relative risk of human rabies cases, indicating that eliminating dog-mediated human rabies could be achievable. Funding The study was supported by the Communicable Disease Control (CDC) Division of the Directorate General of Health Services (DGHS) of the People's Republic of Bangladesh

Phenotypic, Genotypic, and Antibiotic Sensitivity Patterns of Strains Isolated from the Cholera Epidemic in Zimbabwe▿

This paper details the phenotypic, genotypic, and antibiotic sensitivity patterns of 88 Vibrio cholerae strains from Zimbabwe. Of the 88 strains, 83 were classified as “altered El Tor” and 5 as “hybrid El Tor” strains. All of the strains were susceptible to tetracycline, doxycycline, ciprofloxacin, and azithromycin by disc diffusion, but susceptibility to tetracycline and azithromycin diminished when observed using the MIC method

Simultaneous Detection of Six Diarrhea-Causing Bacterial Pathogens with an In-House PCR-Luminex Assay

Diarrhea can be caused by a range of pathogens, including several bacteria. Conventional diagnostic methods, such as culture, biochemical tests, and enzyme-linked immunosorbent assay (ELISA), are laborious. We developed a 7-plex PCR-Luminex assay to simultaneously screen for several of the major diarrhea-causing bacteria directly in fecal specimens, including pathogenic Aeromonas, Campylobacter jejuni, Campylobacter coli, Salmonella, Shigella, enteroinvasive Escherichia coli (EIEC), Vibrio, and Yersinia. We included an extrinsic control to verify extraction and amplification. The assay was first validated with reference strains or isolates and exhibited a limit of detection of 103 to 105 CFU/g of stool for each pathogen as well as quantitative detection up to 109 CFU/g. A total of 205 clinical fecal specimens from individuals with diarrhea, previously cultured for enteric pathogens and tested for Campylobacter by ELISA, were evaluated. Using these predicate methods as standards, sensitivities and specificities of the PCR-Luminex assay were 89% and 94% for Aeromonas, 89% and 93% for Campylobacter, 96% and 95% for Salmonella, 94% and 94% for Shigella, 92% and 97% for Vibrio, and 100% and 100% for Yersinia, respectively. All discrepant results were further examined by singleplex real-time PCR assays targeting different gene regions, which revealed 89% (55/62 results) concordance with the PCR-Luminex assay. The fluorescent signals obtained with this approach exhibited a statistically significant correlation with the cycle threshold (CT) values from the cognate real-time PCR assays (P < 0.05). This multiplex PCR-Luminex assay enables sensitive, specific, and quantitative detection of the major bacterial causes of gastroenteritis