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Myasthenia gravis (MG) is an autoimmune disease mediated by anti-acetylcholine receptor (AChR) antibodies and dependent on CD4 positive T lymphocytes (CD4+T) cells. MicroRNA (miRNA) is an endogenous small single-stranded non-coding RNA that involved in post-transcriptional regulation and plays an important role in differentiation and function of CD4+T cells. Increasing evidences have shown that changes of miRNAs happened in MG patients, which may participate in the occurrence and development of MG by regulating CD4+T cells, and miRNA may be a potential therapeutic target for MG. In this paper, relationship between miRNA and MG was reviewed in order to provide new ideas for further research on the pathogenesis and clinical diagnosis and treatment of MG. [ABSTRACT FROM AUTHOR]

[Objectives] The petaling of a ductile metal plate penetrated by a sharp-nosed missiles is a common damage mode. In order to analyze its formation process, numerical simulation is carried out. [Methods] First, a simulation model of striking the metal plate by sharp-nosed missile is established on the basis of experiments involving missiles perforating targets, and the material constants are acquired from material mechanical characteristic experiments. The petaling procedure is then studied, as well as the stress states of typical elements in the petaling cracking area. The influence on the simulation results is subsequently contrasted by different failure criteria. [Results] The results show that the petaling process is complex and can be mainly divided into four distinct stages:butterfly heaving, hole enlargement, petal appearance and expansion, and entire movement of damaged region. The stress states of the cracking area are complicated and the petaling shape cannot be sufficiently predicted by the constant strain criterion; this requires the introduction of the JC failure model which considers the influence of stress triaxiality. [Conclusions] The results of this paper can provide references for the modification of typical petaling cracking theory and evaluation.

The direct functionalization of inert C(sp3)‐H bonds to form carbon‐carbon and carbon‐heteroatom bonds offers vast potential for chemical synthesis and therefore receives increasing attention. At present, most successes come from strategies using metal catalysts/reagents or photo/electrochemical processes. The use of organocatalysis for this purpose remains scarce, especially when dealing with challenging C−H bonds such as those from simple alkanes. Here we disclose the first organocatalytic direct functionalization/acylation of inert C(sp3)‐H bonds of completely unfunctionalized alkanes. Our approach involves N‐heterocyclic carbene catalyst‐mediated carbonyl radical intermediate generation and coupling with simple alkanes (through the corresponding alkyl radical intermediates generated via a hydrogen atom transfer process). Unreactive C−H bonds are widely present in fossil fuel feedstocks, commercially important organic polymers, and complex molecules such as natural products. Our present study shall inspire a new avenue for quick functionalization of these molecules under the light‐ and metal‐free catalytic conditions. [ABSTRACT FROM AUTHOR]

The development of catalytic synthetic approaches towards molecular complexity from simple materials continues to be an ultimate goal in synthetic chemistry. Over the past decades, N‐heterocyclic carbene (NHC) organocatalysis has been extensively investigated to provide opportunities for a vast number of novel chemical transformations. Various activation modes and reactive intermediates enabled by NHC small‐molecule catalysts, such as Breslow intermediates, (homo)enolates, acyl azoliums and their derived unsaturated azoliums exhibit great potential in the construction of complicated skeletons. This personal account will summarize our group's recent work in the exploration of new activation modes of NHC catalysis towards molecular complexity with a focus on the development and applications of NHC to achieve diversity and enantioselectivity in the preparation of functional molecules. [ABSTRACT FROM AUTHOR]

The development of catalyst‐controlled methods for direct functionalization of two distinct C−H bonds represents an appealing approach for C−C formations in synthetic chemistry. Herein, we describe an organocatalytic approach for straightforward acylation of C(sp3)−H bonds employing readily available aldehyde as "acyl source" involving dehydrogenative coupling of aldehydes with ether, amine, or benzylic C(sp3)−H bonds. The developed method affords a broad range of ketones under mild conditions. Mechanistically, simple ortho‐cyanoiodobenzene is essential in the oxidative radical N‐heterocyclic carbene catalysis to give a ketyl radical and C(sp3) radical through a rarely explored intermolecular hydrogen atom transfer pathway, rendering the acylative C−C formations in high efficiency under a metal‐ and light‐free catalytic conditions. Moreover, the prepared products show promising anti‐bacterial activities that shall encourage further investigations on novel agrochemical development. [ABSTRACT FROM AUTHOR]