A Density Functional Theory and Microkinetic Study of Acetylene Partial Oxidation on the Perfect and Defective Cu2O (111) Surface Models.

The catalytic removal of C2H2 by Cu2O was studied by investigating the adsorption and partial oxidation mechanism of C2H2 on both perfect (stoichiometric) and CuCUS-defective Cu2O (111) surface models using density functional theory calculations. The chemisorption of C2H2 on perfect and defective surface models needs to overcome the energy barrier of 0.70 and 0.81 eV at 0 K. The direct decomposition of C2H2 on both surface models is energy demanding with the energy barrier of 1.92 and 1.62 eV for the perfect and defective surface models, respectively. The H-abstractions of the chemisorbed C2H2 by a series of radicals including H, OH, HO2, CH3, O, and O2 following the Langmuir−Hinshelwood mechanism have been compared. On the perfect Cu2O (111) surface model, the activity order of the adsorbed radicals toward H-abstraction of C2H2 is: OH > O2 > HO2 > O > CH3 > H, while on the defective Cu2O (111) surface model, the activity follows the sequence: O > OH > O2 > HO2 > H > CH3. The CuCUS defect could remarkably facilitate the H-abstraction of C2H2 by O2. The partial oxidation of C2H2 on the Cu2O (111) surface model tends to proceed with the chemisorption process and the following H-abstraction process rather than the direct decomposition process. The reaction of C2H2 H-abstraction by O2 dictates the C2H2 overall reaction rate on the perfect Cu2O (111) surface model and the chemisorption of C2H2 is the rate-determining step on the defective Cu2O (111) surface model. The results of this work could benefit the understanding of the C2H2 reaction on the Cu2O (111) surface and future heterogeneous modeling.

Suppression of hnRNP A1 binding to HK1 RNA leads to glycolytic dysfunction in Alzheimer's disease models.

Objective: To investigate the mechanism of RNA-binding protein hnRNP A1 in mouse hippocampal neurons (HT22) on glycolysis. Methods: RIP and CLIP-qPCR were performed by HT22 in vitro to observe the mechanism of hnRNP A1 regulating the expression of key proteins in glycolysis. The RNA binding domain of hnRNP A1 protein in HT22 was inhibited by VPC-80051, and the effect of hnRNP A1 on glycolysis of HT22 was observed. Lentivirus overexpression of hnRNP A1 was used to observe the effect of overexpression of hnRNP A1 on glycolysis of Aß25-35-injured HT22. The expression of hnRNP A1 in brain tissues of wild-type mice and triple-transgenic (APP/PS1/Tau) AD mice at different ages was studied by Western blot assay. Results: The results of RIP experiment showed that hnRNP A1 and HK1 mRNA were significantly bound. The results of CLIP-qPCR showed that hnRNP A1 directly bound to the 2605-2821 region of HK1 mRNA. hnRNP A1 inhibitor can down-regulate the expression of HK1 mRNA and HK1 protein in HT22 cells. Overexpression of hnRNP A1 can significantly reduce the toxic effect of Aß25-35 on neurons via the hnRNP A1/HK1/ pyruvate pathway. In addition, inhibition of hnRNP A1 binding to amyloid precursor protein (APP) RNA was found to increase Aß expression, while Aß25-35 also down-regulated hnRNP A1 expression by enhancing phosphorylation of p38 MAPK in HT22. They interact to form bidirectional regulation, further down-regulating the expression of hnRNP A1, and ultimately aggravating glycolytic dysfunction. Protein immunoblotting showed that hnRNP A1 decreased with age in mouse brain tissue, and the decrease was greater in AD mice, suggesting that the decrease of hnRNP A1 may be a predisposed factor in the pathogenesis of AD.

Ab Initio Calculation of Surface Thermochemistry for Popular Solid Transition Metal-Based Species.

This work reports the thermochemistry calculations for solid-phase periodic models of ten popular transition metal-based species. These model structures were refined to stable geometry by geometric optimization along with calculating the thermodynamic properties including enthalpy, entropy, heat capacity at constant pressure, and Gibbs free energy by DMol3 package via first-principles ab initio calculations. The temperature-dependent thermochemistry values were converted to a NASA seven-polynomial format. The behavior of different thermodynamic parameters based on temperature was investigated and their comparative analysis was done. A higher number of atoms tends to show higher thermodynamic values. Moreover, these thermodynamic values agree reasonably well with previously reported experimental and computational values. Metal copper shows higher thermodynamic values as compared to its oxide. The thermodynamic properties of lanthanum-based oxides have been newly calculated through the ab initio method. Amorphous structures reveal higher thermodynamic values compared to their crystalline counterparts. A comparison between different transition metal-based species gives a better understanding of the different crystalline structures and their surface sites. These calculated thermodynamic data and polynomials can be used for a variety of thermodynamic calculations and kinetic modeling.

An efficient and innovative catalytic reactor for VOCs emission control.

Efficient mixing and thermal control are important in the flow reactor for obtaining a high product yield and selectivity. Here, we report a heterogeneous chemical kinetic study of propene oxidation within a newly designed catalytic jet-stirred reactor (CJSR). To better understand the interplay between the catalytic performances and properties, the CuO thin films have been characterized and the adsorbed energies of propene on the adsorbed and lattice oxygen were calculated using density functional theory (DFT) method. Structure and morphology analyses revealed a monoclinic structure with nano-crystallite size and porous microstructure, which is responsible for holding an important quantity of adsorbed oxygen. The residence time inside the flow CJSR (1.12-7.84 s) makes it suitable for kinetic study and gives guidance for scale-up. The kinetic study revealed that using CJSR the reaction rate increases with O2 concentration that is commonly not achievable for catalytic flow tube reactor, whereas the reaction rate tends to increase slightly above 30% of O2 due to the catalyst surface saturation. Moreover, DFT calculations demonstrated that adsorbed oxygen is the most involved oxygen, and it has found that the pathway of producing propene oxide makes the reaction of C3H6 over CuO surface more likely to proceed. Accordingly, these findings revealed that CJSR combined with theoretical calculation is suitable for kinetic study, which can pave the way to investigate the kinetic study of other exhaust gases.