The GaCl-Catalyzed Knoevenagel Condensation To Achieve Acceptor-Donor-Acceptor Small-Molecule Acceptors: A DFT Mechanistic Study.

Herein, the reaction mechanism for the GaCl-catalyzed Knoevenagel condensation of 2-formylindacenodithieno[3,2-]thiophene (ITIC-CHO) and active methylene compound 1,1-dicyanomethylene-3-indanone (IC) to synthesize ITIC in the presence of acetic anhydride was investigated using the density functional theory (DFT) method. The calculated results indicate that this reaction follows a bimolecular GaCl catalytic mechanism. The free energy span for the monomolecular GaCl catalytic mechanism is the highest (31.

The rational design of high-performance graphene-based single-atom electrocatalysts for the ORR using machine learning.

In this work, high-performance two-dimensional (2D) graphene-based single-atom electrocatalysts (ZZ/ZA-MNC) for the oxygen reduction reaction (ORR) were screened out using machine learning (ML). A model was built for the fast prediction of electrocatalysts and two descriptors valence electron correction (VEc) and degree of construction differences (DC) were proposed to improve the accuracy of the model prediction. Two evaluation criteria, high-performance catalyst retention rate and high-performance catalyst occupancy rate , were proposed to evaluate the accuracy of ML models in high-performance catalyst screening.

Improved Elastic Image Pair Method for Finding Transition States.

The elastic image pair (EIP) method is a robust method for finding approximate transition states between two local minima. However, the original implementation of the method had some limitations. In this work, we present an improved EIP method, in which the moving procedure of the image pair and the convergence strategy are modified.

Hydride Relay Exchange Mechanism for the Heterocyclic C-H Arylation of Benzofuran and Benzothiophene Catalyzed by Pd Complexes.

The mechanism and regioselectivity of the heterocyclic C-H arylation of benzofuran and benzothiophene catalyzed by Pd(OAc) complexes were investigated using the density functional theory (DFT) method. The Pd(0)L(PhI) complex (L = HOAc) is proposed to be the catalytic species. Compared to the traditional Heck-type mechanism, concerted metalation-deprotonation (CMD) mechanism, and electrophilic aromatic substitution (SAr) mechanism for the C-H arylation, a new hydride relay exchange mechanism was proposed for the benzoheterocyclic C-H arylation catalyzed by Pd complexes, which consists of two redox processes between Pd(II) and Pd(0) species to complete the regioselective C-H activation.

Elastic Image Pair Method for Finding Transition States on Potential Energy Surfaces Using Only First Derivatives.

Herein, an elastic image pair (EIP) method is proposed to search transition states between two potential-energy minima using only first derivatives. In this method, two images are generated, and the spring forces are added to the images to control the distance between the two images. Transition states are reached when the force and the distance of the image pair are both converged.

The Role of AQ in the Regioselectivity of Strong Alkyl C-O Bond Activation Catalyzed by Pd(OAc): A Density Functional Theory Mechanistic Study.

A density functional theory method was employed to investigate the mechanism of C-O bond activation of butanoic acid substrates bearing the 8-aminoquinoline (AQ) group catalyzed by Pd(OAc). The whole reaction consists of five fundamental steps: the chelation of substrate , the C-H activation step, the C-N coupling step, the protodepalladation step, and the release of the final product. The calculated results indicated that the protodepalladation step is the rate-determining step with a free energy barrier of 24.

Functional expression of TRPA1 channel, TRPV1 channel and TMEM100 in human odontoblasts.

TRPA1 and TRPV1 channels respond to external stimulation as pain mediators and form a complex with a transmembrane protein TMEM100 in some tissues. However, their expression and interaction in dental pulp is unclear. To investigate the functional co-expression of TRPA1 channel, TRPV1 channel and TMEM100 in human odontoblasts (HODs), immunohistochemistry, immunofluorescence staining and Western blot were used to study their co-localization and expression in both native HODs and cultured HOD-like cells.

Tumor Necrosis Factor-α Regulates the TRPA1 Expression in Human Odontoblast-Like Cells.

Purpose: Transient receptor potential cation channel, subfamily A, member 1 (TRPA1) is a promiscuous chemical nociceptor involved in the perception of cold hypersensitivity, mechanical hyperalgesia and inflammatory pain in human odontoblasts (HODs). Here, we aimed to study the underlying mechanism in which inflammatory cytokine tumor necrosis factor (TNF)-α regulated the expression of TRPA1 channel at both cellular and subcellular levels.

Materials And Methods: Immunohistochemistry was used to confirm the expression of TRPA1 channel in HODs.

Asymmetric Induction with a Chiral Amine Catalyzed by a Ru-PNP Pincer Complex: Insight from Theoretical Investigation.

In this paper, the mechanism of asymmetric amination of a racemic alcohol with Ellman's sulfinamide and the origin of diastereoselectivity catalyzed by a Ru-PNP pincer complex were studied using density functional theory (DFT). The mechanism involves dehydrogenation of the racemic alcohol, C-N coupling, and hydrogen transfer from the catalyst to the in situ formed imine. The calculated results indicate that both the alcohol dehydrogenation and imine hydrogenation are stepwise.

Effects of at-home bleaching and resin infiltration treatments on the aesthetic and psychological status of patients with dental fluorosis: A prospective study.

Objective: This study aims to evaluate the effect of the combination approach of at-home bleaching (HB) and resin infiltration (RI) techniques on different severity degrees of dental fluorosis (DF) and further analyze the psychological changes caused by HB and RI in patients.

Method: Twenty-two patients (4 males, 18 females, 27.8 ± 1.

High activity expression of D-amino acid oxidase in Escherichia coli by the protein expression rate optimization.

Two categories of expression systems with different promoters and substitutive ribosome binding site region (RBS) were constructed in order to improve the soluble expression of d-amino acid oxidase (DAAO) basing on the hypothesis that the optimal promoter and suitable RBS would provide the recombinant expression system with better matched expression rate, which served as key factor to the heterogenous synthesis of soluble protein. The results showed that with rational promoter recombination and delicate RBS substitution, significant increase of DAAO activity (20-fold) was obtained for strain JM105/pGEMKT-Tac-R-DAAO over the previously constructed strain BL21(DE3)/pET-DAAO. Furthermore, similar optimization strategy proved feasible in the active expression of other enzymes such as glutaryl-7-aminocephalosporanic acid acylase (GCA) and N-Carbamyl-D-amino acid amidohydrolase (D-Case).

High soluble expression of D-amino acid oxidase in Escherichia coli regulated by a native promoter.

To express high-active soluble D-amino acid oxidase (DAAO), a constitutive plasmid that is regulated by a native hydantoinase promoter (P(Hase)), was constructed. A D-amino acid oxidase gene (dao) was ligated with the P(Hase) and cloned into pGEMKT to constitutively express protein of DAAO without the use of any inducer such as isopropyl beta-D-1-thiogalactopyranoside which is poisonous to the cells and environment. The ribosome binding site region, host strain, and fermentation conditions were optimized to increase the expression level.