Layer thickness dependent plastic deformation mechanism in Ti/TiCu dual-phase nano-laminates

Crystalline/amorphous nanolaminate is an effective strategy to improve the mechanical properties of metallic materials,but the underlying deformation mechanism is still under the way of exploring.Here,the mechanical properties and plastic deformation mechanism of Ti/TiCu dual-phase nanolaminates(DPNLs)with different layer thicknesses are investigated using molecular dynamics simulations.The results indicate that the influence of the layer thickness on the plastic deformation mechanism in crystalline layer is negligible,while it affects the plastic deformation mechanism of amorphous layers distinctly.The crystallization of amorphous TiCu is exhibited in amorphous parts of the Ti/TiCu DPNLs,which is inversely proportional to the layer thickness.It is observed that the crystallization of the amorphous TiCu is a process driven by stress and heat.Young's moduli for the Ti/TiCu DPNLs are higher than those of composite material due to the amorphous/crystalline interfaces.Furthermore,the main plastic deformation mechanism in crystalline part:grain reorientation,transformation from hexagonal-close-packed-Ti to face-centered cubic-Ti and body-centered cubic-Ti,has also been displayed in the present work.The results may provide a guideline for design of high-performance Ti and its alloy.

Molecular dynamics study on mechanical behaviors of Ti/Ni nanolaminate with a pre-existing void

Metallic nanolaminated materials possess excellent mechanical properties due to their unique modulation structures and interfacial properties.However,how microdefects affect their mechanical properties is still uncertain.To evaluate the influences of void location(in the crystalline layer and the Ti/Ni interface),void diameter(d)and thickness of the intermediate layer(h)on overall tensile behaviors,various types of defective Ti/Ni nanolaminates with pre-existing void are established by the molecular dynamics method in this work.The results indicate that the strength and plastic deformation mechanisms are strongly dependent on those determinants.Yield stresses of Ti/Ni nanolaminates decrease distinctly with increasing void diameter,while peak stresses with a void in the crystalline layer decrease with increasing d/h.Different void locations lead eventually to disparate initial plastic deformation carriers around the void,and various evolutions in the microstructure of the defective Ti/Ni nanolaminates.The Ti/Ni interface plays a significant role in the tensile process.The semi-coherent interface impedes new grains and lattice dislocations from passing across the interface,while the incoherent interface facilitates dislocations generating and sliding along the interface,and absorbs the dislocations moving to the interface.The results also indicate that the strain rate significantly affects the evolution of the microstructure and the tensile properties of defective Ti/Ni nanolaminates.

Exosome miRNAs profiling in serum and prognostic evaluation in patients with multiple myeloma

MicroRNAs(MiRNAs)carried by exosomes play pivotal roles in the crosstalk between cell components in the tumor microenvironment.Our study aimed at identifying the expression profile of exosomal miRNAs(exo-miRNAs)in the serum of multiple myeloma(MM)patients and investigating the regulation networks and their potential functions by integrated bioinformatics analysis.Exosomes in serum from 19 newly diagnosed MM patients and 9 healthy donors were isolated and the miRNA profile was investigated by small RNA sequencing.Differential expression of exo-miRNAs was calculated and target genes of miRNAs were predicted.CytoHubba was applied to identify the hub miRNAs and core target genes.The LASSO Cox regression model was used to develop the prognostic model,and the ESTIMATE immune score was calculated to investigate the correlation between the model and immune status in MM patients.The top six hub differentially expressed serum exo-miRNAs were identified.513 target genes of the six hub exo-miRNAs were confirmed to be differentially expressed in MM cells in the Zhan Myeloma microarray dataset.Functional enrichment analysis indicated that these target genes were mainly involved in mRNA splicing,cellular response to stress,and deubiquitination.13 core exo-miRNA target genes were applied to create a novel prognostic signature to provide risk stratification for MM patients,which is associated with the immune microenvironment of MM patients.Our study comprehensively investigated the exo-miRNA profiles in MM patients.A novel prognostic signature was constructed to facilitate the risk stratification of MM patients with distinct outcomes.