An unprecedented Pd‐catalyzed regioselective activation of gem‐difluorinated cyclopropanes induced by CC bond cleavage is reported. It provides a general and efficient access to a variety of ...2‐fluoroallylic amines, ethers, esters, and alkylation products in high Z‐selectivity, which are important skeletons in many biologically active molecules. In addition, the transformation represents the first general application of gem‐difluorinated cyclopropanes as reaction partners in transition‐metal‐catalyzed cross‐coupling reaction.
CC bond cleavage under Pd catalysis induces a regioselective activation of gem‐difluorinated cyclopropanes. The reaction provides access to a variety of 2‐fluoroallylic scaffolds with high Z‐selectivity and represents the first general application of gem‐difluorinated cyclopropanes as reaction partners in transition‐metal‐catalyzed cross‐coupling reactions.
The classroom teaching and quality evaluation of college English teachers is an effective way to evaluate the teaching quality and improve the teaching level of teachers. But there is uncertainty and ...fuzziness in the process of teaching and quality evaluation. Therefore, based on the data mining technology, the analytic hierarchy process is used to construct the evaluation index body. Then the indexes which have important influence on the evaluation result are selected as BP neural network input. Finally, the neural network teaching and quality evaluation model is established, and the improved algorithm is simulated. The validity of this method is verified by experiments, which can improve the accuracy of college English teaching and quality evaluation. With the help of SPSS and Weka data mining tools, this paper uses a variety of data mining means to conduct in-depth mining analysis of various teaching operation status data, explore the complex relationship behind the data and its value significance, then further propose how to effectively use data mining to implement teaching quality monitoring methods and measures, and discuss how to combine the analysis results for optimizing the use of student assessment data, innovating the way of college students The study also discusses how to combine the analysis results to optimize the use of student evaluation data and to innovate the way of guiding the quality assessment of English courses for college students, to provide meaningful references for the implementation of English teaching quality assessment.
Primary familial brain calcification (PFBC) is a genetically heterogeneous disorder characterized by bilateral calcifications in the basal ganglia and other brain regions. The genetic basis of this ...disorder remains unknown in a significant portion of familial cases. Here, we reported a recessive causal gene, MYORG, for PFBC. Compound heterozygous or homozygous mutations of MYORG co-segregated completely with PFBC in six families, with logarithm of odds (LOD) score of 4.91 at the zero recombination fraction. In mice, Myorg mRNA was expressed specifically in S100β-positive astrocytes, and knockout of Myorg induced the formation of brain calcification at 9 months of age. Our findings provide strong evidence that loss-of-function mutations of MYORG cause brain calcification in humans and mice.
•MYORG is a major causal gene for autosomal recessive PFBC•Specific expression of MYORG suggests astrocyte involves in PFBC•Myorg knockout mice develops calcium deposits in the brain
Yao et al. provide evidence that MYORG is a major causal gene for autosomal recessive PFBC by a comprehensive strategy combining whole-exome sequencing analysis, Sanger sequencing, linkage analysis, RNA expression analysis, and a mouse model.
As robots normally perform repetitive work, reinforcement learning (RL) appears to be a promising tool for designing robot control. However, the learning cycle of control strategy tends to be long, ...thereby limiting the applications of RL for a real robotic system. This article proposes model-based actor-critic learning for optimal tracking control of robotic systems to address this limitation. A preconstructed critic is defined in the framework of linear quadratic tracker, and a model-based actor update law is presented on the basis of deterministic policy gradient algorithm to improve learning efficiency. A low gain parameter is introduced in the critic to avoid input saturation. Compared with neural network-based RL, the proposed method including the preconstructed critic and actor, has rapid, steady, and reliable learning process, which is friendly for the physical hardware. The performance and effectiveness of the proposed method are validated using a dual-robot test rig. The experimental results show that the proposed learning algorithm can train multiple robots to learn their optimal tracking control laws within a training time of 200 s.
The Party in the 1990s merger boom into China, the real estate industry in the “merger and acquisition of the road” can be said to be in full swing With the change of social policies, “business ...transformation”, that is, seeking diversified development, has become one of the important motivations for M&A in the context of increasingly difficult and expensive “land acquisition” And Sunac China by virtue of the amazing speed and scale of mergers and acquisitions, in the real estate industry of mergers and acquisitions boom to stand out, people’s attention. Therefore, this paper classifies the series of M&A cases of Sunac China according to the M&A motivation, mainly discusses the two M&A cases based on the “business transformation” M&A motivation, analyzes the M&A performance respectively, summarizes the problems that enterprises tend to ignore when making cross-industry investment, and puts forward the corresponding investment countermeasures, which has certain reference significance for enterprises’ cross-industry investment.
China has a rich and colorful culture, and the cultural appreciation value and research value are very high. It should be our important responsibility and obligation to help and guide more tourists ...to learn, understand, appreciate and appreciate China’s profound cultural accumulation. At present, the rapid development of “Internet” information technology and the gradual popularization of intelligent terminals have provided important opportunities and built an effective platform for the external dissemination of cultural tourist attractions and culture, as well as the development of foreign language identification, interpretation and other services. Shandong is not only our country economic province, and the red tourist attractions, red sites, red resources is very rich, Shandong cultural tourism got rapid development in recent years, under the new situation, how to strengthen the red culture in Shandong province give full play to the advantage, strengthen the effective implementation of cultural drive strategy should be an important research topic.
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This study in the Shandong red culture foreign communication significance and value, on the basis of the red culture resources in Shandong province, analyzes the current Shandong red culture tourism attractions bilingual service present situation and the existing problems, provide improvement and optimization of countermeasures and path, to strengthen the development of Shandong red culture, red culture and promote the direction towards the cultural industry resources and development, really make the red culture effectively into real productivity, into economic benefits, better boost the high quality of economic and social development in Shandong province.
A zinc(ii) coordination polymer {Zn3(mtrb)3(btc)2·3H2O}n (1) was synthesized and characterized (mtrb = 1,3-bis(1,2,4-triazole-4-ylmethyl)benzene, btc = 1,3,5-benzenetricarboxylate). The polymer 1 ...shows an unusual (3,4,4)-coordinated self-catenated 3D network with the point symbol of {63}2{62·82·102}{64·82}2. The polymer 1 is the first luminescent sensor for the detection of 2-amino-4-nitrophenol (ANP). The polymer 1 is also a good luminescence sensor for detection of TNP, 2,4-DNP, 4-NP, ANP and 2-NP in MeOH, particularly for TNP. The order of detection efficiency is TNP > 2,4-DNP > 4-NP > ANP > 2-NP. The polymer 1 also exhibits high sensitivity and selectivity as a luminescence sensor for the detection of Fe3+, Cr2O72- and CrO42- in aqueous solution. Our experiments showed that the presence of interfering ions had no significant effect on the sensing of Fe3+, Cr2O72- or CrO42- ions. The detection limits for TNP, ANP, Fe3+, Cr2O72- and CrO42- are 0.22 μM, 4.12 μM, 1.78 μM, 2.83 μM, and 4.52 μM, respectively. The luminescence sensor is stable and can be recycled for detection at least five times. The possible quenching mechanisms are discussed. The polymer 1 is also an effective photocatalyst for degradation of methylene blue (MB) under visible or UV light irradiation.
Water is essential in the evolution of life and plays an important role in the structure and function of the basic substances of life, such as protein and DNA. However, the specific details of the ...role of water with respect to chitin, the most abundant biomacromolecule on Earth after cellulose, remain unclear. In this study, atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) was used to explore the effects of hydrogen bonds (H-bonds) on the single-molecule mechanics of chitin. Comparative experiments showed that a single chitin chain exhibited the same single-chain natural elasticity as cellulose in nonane, indicating that a single chitin chain can form strong intrachain H-bonds in nonane. Moreover, the single-chain elasticity of chitin obtained in dimethyl sulfoxide (DMSO) was consistent with that of cellulose, and both superposed well with the theoretical model (QM-FJC) to show the single-chain elasticity of the chitin/cellulose backbone, indicating that DMSO can eliminate almost all the intrachain H-bonds of single chitin chains. However, when water was introduced as the surrounding environment, the intrachain H-bonds of chitin were found to be weaker than those of cellulose, which is supported by the AFM mapping results. Single-molecule studies reveal that water is a unique solvent for chitin, and the nanomechanics and hydrophobicity of chitin can be influenced by an external solvent (water in this work) through regulation of the intrachain H-bonds. The present study casts new insight into the role of H-bonds and water in the structures and functions of polysaccharides.
Single-molecule studies reveal that water is a unique solvent for chitin: the nanomechanics and hydrophobicity of chitin can be influenced by external solvent through regulation of the intrachain H-bond.
Five new zero-dimensional hybrid manganese halides based on discrete MnCl
4
2−
tetrahedrons were prepared and used as highly efficient green-light emitters. Through rational management of organic ...cations to tailor the Mn Mn separation distances between neighboring MnCl
4
2−
tetrahedrons, the photoluminescence quantum yield increased significantly from 7.98% to 81.11%.
Five new zero-dimensional hybrid manganese halides based on discrete MnCl
4
2−
tetrahedrons were prepared and used as highly efficient green-light emitters.
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