Similar and dissimilar combinations of a 1000 MPa galvanised dual phase (DP) steel and a 980 MPa transformation induced plasticity (TRIP) steel were resistance spot welded under different welding and heat treatment parameters. The microstructure and mechanical properties of spot welds were evaluated using metallographic technique, microhardness and tensile shear tests. The results showed that the tendency to fail in the pullout mode increased in the order of DP/ DP, TRIP/TRIP and DP/TRIP welds, which was caused by the different hardness distribution, carbon equivalent and susceptibility to shrinkage void formation of spot welds for different combinations. In the study of the effects of heat treatments on the DP/TRIP welds, the pre-heating procedure improved the splash of welding to some extent. When the cooling time was larger than or equal to 1000 ms, the post-heating procedure improved the mechanical properties of spot welds owing to the temper of spot weld microstructure.

No abstract

The SARS-CoV-2 virus is still spreading worldwide, and there is an urgent need to effectively prevent and control this pandemic. This study evaluated the potential efficacy of Egg Yolk Antibodies (IgY) as a neutralizing agent against the SARS-CoV-2. We investigated the neutralizing effect of anti-spike-S1 IgYs on the SARS-CoV-2 pseudovirus, as well as its inhibitory effect on the binding of the coronavirus spike protein mutants to human ACE2. Our results show that the anti-Spike-S1 IgYs showed significant neutralizing potency against SARS-CoV-2 pseudovirus, various spike protein mutants, and even SARS-CoV in vitro. It might be a feasible tool for the prevention and control of ongoing COVID-19.

Similar and dissimilar combinations of a 1000 MPa galvanised dual phase (DP) steel and a 980 MPa twining-induced plasticity (TWIP) steel were resistance spot welded under different welding parameters. The microstructure, expulsion situation, nugget size and mechanical properties of spot welds were evaluated systematically. The results showed that the differences of microstructure and chemical compositions caused that the weld nugget hardness increases in the order of TWIP/TWIP, DP/TWIP and DP/DP. The lower melting point and heat conductivity of the TWIP steel and the lower electric resistance of the zinc coat on the DP steel caused that the expulsion occurring current increased in the order of TWIP/TWIP, DP/TWIP and DP/DP and under the same welding condition the nugget diameter increased in the order of DP/DP, DP/ TWIP and TWIP/TWIP. Furthermore, the tensile shear failure mode and location depends on the nugget size, microstructure and hardness distribution of spot weld.