Effects of solidification on flow dynamics: A novel comprehension of defects formation in laser penetration welding

The laser penetration welding for medium-thickness plates struggles with unstable molten pool behavior and a limited processing window, often leading to welding defects including spatters, depressions, and especially humps. In this study, forming processes of the defects were observed by using a high-speed camera, and forming mechanism of the defects were then analyzed in detail by simultaneously considering the influences of force and solidification. It was clear that the mass loss caused by spattering during the heating phase contributed to the depression, which was consistent with the existing knowledge. However, the formation mechanism of humps concluded in this study was different to the present understanding. Apart from the influences of force, the effects of solidification on molten pools and humps were analyzed. Under the specific conditions, middle part of molten pool solidified rapidly, causing localized necking, and disrupting the circular flow of the molten metal. As a result, molten metal once flowed downward due to the gravity and temperature can no longer refill to the upper part again, leading to the accumulation of molten metal at lower part and ultimately the formation of humps. These findings offered a fresh perspective on the formation of hump, provided valuable guidance for enhancing the quality and efficiency of thick-plate laser welding

Identification of key genes in sepsis-induced cardiomyopathy based on integrated bioinformatical analysis and experiments in vitro and in vivo

Introduction Sepsis is a life-threatening disease that damages multiple organs and induced by the host’s dysregulated response to infection with high morbidity and mortality. Heart remains one of the most vulnerable targets of sepsis-induced organ damage, and sepsis-induced cardiomyopathy (SIC) is an important factor that exacerbates the death of patients. However, the underlying genetic mechanism of SIC disease needs further research. Methods The transcriptomic dataset, GSE171564, was downloaded from NCBI for further analysis. Gene expression matrices for the sample group were obtained by quartile standardization and log2 logarithm conversion prior to analysis. The time series, protein-protein interaction (PPI) network, and functional enrichment analysis via Gene Ontology and KEGG Pathway Databases were used to identify key gene clusters and their potential interactions. Predicted miRNA-mRNA relationships from multiple databases facilitated the construction of a TF-miRNA-mRNA regulatory network. In vivo experiments, along with qPCR and western blot assays, provided experimental validation. Results The transcriptome data analysis between SIC and healthy samples revealed 221 down-regulated, and 342 up-regulated expressed genes across two distinct clusters. Among these, Tpt1, Mmp9 and Fth1 were of particular significance. Functional analysis revealed their role in several biological processes and pathways, subsequently, in vivo experiments confirmed their overexpression in SIC samples. Notably, we found TPT1 play a pivotal role in the progression of SIC, and silencing TPT1 showed a protective effect against LPS-induced SIC. Conclusion In our study, we demonstrated that Tpt1, Mmp9 and Fth1 have great potential to be biomarker of SIC. These findings will facilitated to understand the occurrence and development mechanism of SIC

AlSi10Mg alloy nanocomposites reinforced with aluminum-coated graphene: Selective laser melting, interfacial microstructure and property analysis

Graphene has been successfully coated with a nano-Al layer through a novel activating treatment (i.e., organic aluminum reduction method). The nano-Al coated graphene was further processed into AlSi10Mg alloy based composites through a selective laser melting (SLM) process. During the nanocoating of Al on graphene, Al atoms deposited on the graphene through organic aluminum reduction gradually, via nucleation and growth process. There were two primary grain growth patterns: two dimensional (2D) layered growth and three dimensional (3D) island growth, until graphene was coated with Al. The Al-coated graphene was added to the AlSi10Mg alloy, refining the cell, increased the tensile strength, hardness and wear resistance of the alloy. Coating Al on the graphene improved the wetting between graphene and Al, and the addition of Al-coated graphene led to a high nucleation rate, which was responsible for refining the cell. This approach facilitated graphene homogeneous distribution in the Al alloy, the interface between graphene and Al was relatively stable, and the grapheme could pin the dislocation and grain boundary. All these attributes enabled superior mechanical properties to be obtained in the final alloy based nanocomposites