Mechanism of joint formation and characteristics of interface in ultrasonic welding: Literature review

The study of ultrasonic welding has been going on for more than 50 years. The mechanism of joint formation and characterization of the interface in ultrasonically made joints between metal sheets and wires have been the most thought-provoking area for the researchers. The study of post-welding microstructure, the formation of any intermetallic compound at the interface and their effect on the joint strength, the presence of heat affected zone in the ultrasonically joined sheets has been explored but still, arguably the least understood. Interface characteristics are different in similar and dissimilar combinations of metals. This work presents a comprehensive review of literature regarding the studies on the microstructural analysis at the interface of the joints made by Ultrasonic Welding on different combinations of metal sheets. Additionally, this paper provides an analysis of the observations made by different scientists that promote the future scope of research in this area. The study has been confined to Ultrasonic metal welding only

SARS-CoV-2 B.1.617.2 Delta variant replication and immune evasion

Abstract: The B.1.617.2 (Delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in the state of Maharashtra in late 2020 and spread throughout India, outcompeting pre-existing lineages including B.1.617.1 (Kappa) and B.1.1.7 (Alpha)1. In vitro, B.1.617.2 is sixfold less sensitive to serum neutralizing antibodies from recovered individuals, and eightfold less sensitive to vaccine-elicited antibodies, compared with wild-type Wuhan-1 bearing D614G. Serum neutralizing titres against B.1.617.2 were lower in ChAdOx1 vaccinees than in BNT162b2 vaccinees. B.1.617.2 spike pseudotyped viruses exhibited compromised sensitivity to monoclonal antibodies to the receptor-binding domain and the amino-terminal domain. B.1.617.2 demonstrated higher replication efficiency than B.1.1.7 in both airway organoid and human airway epithelial systems, associated with B.1.617.2 spike being in a predominantly cleaved state compared with B.1.1.7 spike. The B.1.617.2 spike protein was able to mediate highly efficient syncytium formation that was less sensitive to inhibition by neutralizing antibody, compared with that of wild-type spike. We also observed that B.1.617.2 had higher replication and spike-mediated entry than B.1.617.1, potentially explaining the B.1.617.2 dominance. In an analysis of more than 130 SARS-CoV-2-infected health care workers across three centres in India during a period of mixed lineage circulation, we observed reduced ChAdOx1 vaccine effectiveness against B.1.617.2 relative to non-B.1.617.2, with the caveat of possible residual confounding. Compromised vaccine efficacy against the highly fit and immune-evasive B.1.617.2 Delta variant warrants continued infection control measures in the post-vaccination era

Optimizacija parametrov procesa za povečanje natezne trdnosti ogljikovega jekla, torno varjenega z gnetenjem

The present study focuses on improving the ultimate tensile strength of friction stir welded carbon steel (AISI 1018). The effect of the process parameters (welding speed, tool RPM, and shoulder diameter) on the response parameters (ultimate tensile strength, percentage elongation and percentage reduction in area) were studied. Response surface methodology was used to develop the mathematical model for response parameters, and the adequacy of the model was checked using analysis of variance (ANOVA). The welding speed and tool RPM were found to affect the ultimate tensile strength significantly. The percentage elongation was affected only by welding speed. The percentage reduction in the area was affected by welding speed and shoulder diameter. The microstructure and microhardness of the weld have been studied and reported in the study

sj-docx-1-pie-10.1177_09544089221130615 - Supplemental material for Fatigue behaviour and impact strength assessment of friction stir-welded carbon steel joints

Supplemental material, sj-docx-1-pie-10.1177_09544089221130615 for Fatigue behaviour and impact strength assessment of friction stir-welded carbon steel joints by Anmol Bhatia and Reeta Wattal in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p

sj-docx-2-pie-10.1177_09544089221130615 - Supplemental material for Fatigue behaviour and impact strength assessment of friction stir-welded carbon steel joints

Supplemental material, sj-docx-2-pie-10.1177_09544089221130615 for Fatigue behaviour and impact strength assessment of friction stir-welded carbon steel joints by Anmol Bhatia and Reeta Wattal in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p

Transmission of B.1.617.2 Delta variant between vaccinated healthcare workers

AbstractBreakthrough infections with SARS-CoV-2 Delta variant have been reported in doubly-vaccinated recipients and as re-infections. Studies of viral spread within hospital settings have highlighted the potential for transmission between doubly-vaccinated patients and health care workers and have highlighted the benefits of high-grade respiratory protection for health care workers. However the extent to which vaccination is preventative of viral spread in health care settings is less well studied. Here, we analysed data from 118 vaccinated health care workers (HCW) across two hospitals in India, constructing two probable transmission networks involving six HCWs in Hospital A and eight HCWs in Hospital B from epidemiological and virus genome sequence data, using a suite of computational approaches. A maximum likelihood reconstruction of transmission involving known cases of infection suggests a high probability that doubly vaccinated HCWs transmitted SARS-CoV-2 between each other and highlights potential cases of virus transmission between individuals who had received two doses of vaccine. Our findings show firstly that vaccination may reduce rates of transmission, supporting the need for ongoing infection control measures even in highly vaccinated populations, and secondly we have described a novel approach to identifying transmissions that is scalable and rapid, without the need for an infection control infrastructure.</jats:p