Mechanical strength and wear resistance of chromium carbides are relatively low compared to other transition metal (TM) carbides, such as TiC or WC. However, carbides can be tailored by partially substituting their host metal elements with other TMs. In this computational study with first-principles calculations, we investigated the effects of TMs on the stability and properties of metastable CrC carbide having a face-centered cubic structure. It is demonstrated that most TMs in IV and V groups can improve the thermodynamic stability of CrC with negative formation energies, meaning that such TM-substituted CrC can be formed using equilibrium or near-equilibrium synthesis routes. Mechanisms for the improved stability and mechanical properties of CrC by TM substitution were investigated through analyzing corresponding changes in the density of states, charge density distribution, and Bader charge. It is shown that the improved stability and properties of TM-substituted CrC result from changes in the distributions of covalent, ionic, and metallic bonds. TM-substituted CrC carbides with different densities provide more alternatives or options for widened applications of the Cr carbide family.
Deep-brain magnetic stimulation (DMS) is an effective therapy for various neuropsychiatric disorders including major depression disorder. The molecular and cellular mechanisms underlying the impacts of DMS on the brain remain unclear. Studies have reported abnormalities in the white matter of depressive brains, suggesting the involvement of myelin and oligodendrocyte pathologies in the development of major depressive disorder. In this study, we use a cuprizone induced demyelination animal model to generate depressive like behaviours and white matter and oligodendrocyte damages. Meanwhile, we treated the animal with DMS 20 minutes daily during the cuprizone challenge or recovery period. Behavioural tests, including nesting, new objective recognition, working memory and depression-like behaviours were tested periodically. Histological staining and western blotting were used to examine the underlying mechanism of DMS. We found that DMS reverse cuprizone induced behavioural deficits in acute demyelination but not during the recovery period. DMS alleviated demyelination and inflammation induced by cuprizone. During the recovery period, DMS had no impacts on overall neural progenitor cell proliferation, but enhanced the maturation of oligodendrocyte. This data suggest that DMS may be a promising treatment option for improving white matter function in psychiatric disorders and neurological diseases in future.Disclosure of interestThe authors have not supplied their declaration of competing interest.
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