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Altitude plays a crucial role in shaping the diversity and distribution of species in forest landscapes in mountainous regions. However, existing studies often lack comprehensive analysis of the intricate relationships among environmental factors, disturbances, and species diversity. This study aims to address this gap by thoroughly analyzing major species' diversity, distribution, and regeneration status, along with their influencing factors, across different altitudinal gradients (1850 to 2350 m). Field surveys were conducted to examine the major species in different vegetation layers of the secondary Picea forest in Guandi Mountain. The key findings from the study include the following: (1) the study area recorded a total of nine species of adult trees, belonging to eight genera in five families, fourteen species of shrubs from eight genera in five families, and fifty-two herb species representing forty-eight genera in twenty-six families. Dominant species varied across layers, with Picea asperata Mast. and Larix principis-rupprechtii Mayr. dominating the arborous layer, Lonicera ferdinandii Franch. and Cotoneaster acutifolius Turcz. in the shrub layer, and Poa pratensis L. and Duchesnea indica (Andrews.) Focke in the herb layer. (2) Altitude significantly influenced species diversity, with the most pronounced effects observed in the shrub and herb layers. (3) Tree species regeneration varied with altitude, with Picea asperata exhibiting the highest regeneration performance, particularly in the high-altitude zone (2250–2350 m). Regeneration parameters were significantly correlated with species diversity indices in both tree and shrub layers. (4) Redundancy analysis revealed that, apart from altitude, cutting (p = 0.015) influenced the species diversity of the tree layer, while annual precipitation (p = 0.006) and temperature (p = 0.01) determined the diversity of the shrub layer. Grazing (p = 0.042) was identified as a determining factor for species diversity in the herb layer. Overall, these findings provide valuable insights into the sustainable management of forest ecosystems in the study area and offer practical guidance for forest management in similar mountainous landscapes worldwide. [ABSTRACT FROM AUTHOR]

In this work, solid spherical, solid cubic and hollow cubic MnO2 microparticles were successfully synthesized via a facile precursor conversion method. All the crystal structures were defined as rare ϵ‐phase. The ϵ‐MnO2 was modified onto the glassy carbon electrode (GCE) to fabricate sensor platform for hydrogen peroxide (H2O2) determination. The catalytic activity of the prepared materials was demonstrated to be in the order: hollow cubes > solid cubes > solid spheres ϵ‐MnO2. The higher electrochemical activity is related to the higher conductivity and more exposed highly active crystal planes instead of BET surface area, electrode active area and surface charge. Additionally, the cubic ϵ‐MnO2 possesses greater catalytic rate constant (K), which is approximately an order of magnitude higher than that of spherical morphology, due to the faster electron transfer rates caused by reduced contact resistance. The proposed sensor possesses the excellent sensitivity, selectivity and stability, and is successfully applied to determine H2O2 in real sample. [ABSTRACT FROM AUTHOR]

Abstract: A new convenient method for the synthesis of dimethyl carbonate from dimethoxymethane and O2 in the presence of catalytic amounts of Cu-MCM-48 was described. The XRD results indicate that the structure of Cu-MCM-48 is gradually distorted with the increase in the copper content, whereas the framework structure of Cu-MCM-48 is basically retained until the incorporated copper content reaches to 0.62wt%. The SEM, TEM and N2 adsorption studies show that copper content of 9.51wt% completely changes the morphology and structure of Cu-MCM-48. Effects of the amount of the incorporated copper in catalyst, catalyst amount used and other reaction conditions on the catalytic activity are investigated in details to obtain the optimized reaction conditions. Short reaction time, easy recycling of the catalyst and excellent yields are the main advantages of this process. [Copyright &y& Elsevier]

Investigating the catalytic ability of an individual catalyst particle helps to understand heterogeneity and can provide new insights into the synthesis of high-efficiency catalysts. Solid-state nanopores have become a promising tool for detecting single molecules/particles due to their high temporal and spatial resolution. Here, we report a nanopore-based strategy for the evaluation and comparison of a single MnO 2 catalyst particle with different morphologies by monitoring the generated O 2 bubbles from the catalytic decomposition of H 2 O 2 . The finite element simulation was introduced to account for the flow velocity and bubble-induced current variation in the nanopore. In particular, the differences in catalytic ability of spherical and cubic MnO 2 have been studied by calculating the production rate and volume of O 2 . It demonstrates that the shape of a single MnO 2 catalyst particle has a significant effect on its catalytic activity indeed.

Reversible N ε -lysine (N ε -Lys) acetylation is a dynamic post-translational modification. Genetic incorporation of N ε -acetyllysine (N ε -AcK) into the specific site of a protein is a powerful method for producing recombinant protein with acetylation and studying the functional role of protein acetylation. Because of the universal existence of deacetylase such as CobB in vivo, the acetyl group of N ε -AcK may be removed from recombinant protein. So in the process of incorporating acetyl lysine into protein, nicotinamide (NAM), a lysine deacetylase (KDAC) inhibitor, is needed to inhibit the KDAC activity and protect the acetyl group of N ε -acetyllysine incorporated from removal in vivo. In this study, we knocked out cobB gene from an E. coli strain and used it as host for incorporating of N ε -AcK into recombinant protein by expanding genetic code. Comparing with the addition of KDAC inhibitor, this is a novel method to protect the acetyl group of N ε -acetyllysine from deacetylation by using cobB knockout strain. Thus, this method provides a better way for protecting recombinant acetylated protein from deacetylation. By knocking out cobB gene from the strain of E. coli, we successfully produced homogeneous acetylated protein by expanding genetic code with a high effectiveness. This method will also provide a good reference for genetically introducing other varieties of modified amino acids into protein., (Copyright © 2017 Elsevier Inc. All rights reserved.)