Blakemerrill5993

Volatile constituents isolated from the stems (S) and leaves (L) of Pimenta dioica (PD) and Pimenta racemosa (PR) during the four seasons were analyzed using GLC/FID (Gas liquid chromatography - flame ionization detector) and GLC/MS (Gas liquid chromatography - mass spectrometry). Eighty-nine compounds were identified in all samples, in which oxygenated monoterpene represented by eugenol was the major constituent in PDS-S3 (autumn) (88.71%) and PDS-S2 (summer) (88.41%). Discrimination between P. dioica and P. racemosa leaves and stems in different seasons was achieved by applying chemometrics analysis comprising Principal Component Analysis (PCA) and Hierarchal Cluster Analysis (HCA). For P. dioica, they were partially segregated where leaves collected from spring and autumn were superimposed, and similarly for P. dioica stems collected in summer and autumn. For P. racemosa leaves, the PCA score plot showed that all seasons were completely segregated from each other, with the winter and autumn samples being ioupled with chemometrics provide a strong tool for the discrimination of samples, while Pimenta could afford a natural drug that could alleviate cancer.The dynamics of single hydrogen bubbles electrogenerated in acidic electrolytes at a Pt microelectrode under potentiostatic conditions is investigated in microgravity during parabolic flights. Three bubble evolution scenarios have been identified depending on the electric potential applied and the acid concentration. The dominant scenario, characterized by lateral detachment of the grown bubble, is studied in detail. For that purpose, the evolution of the bubble radius, electric current and bubble trajectories, as well as the bubble lifetime are comprehensively addressed for different potentials and electrolyte concentrations. We focus particularly on analyzing bubble-bubble coalescence events which are responsible for reversals of the direction of bubble motion. Finally, as parabolic flights also permit hypergravity conditions, a detailed comparison of the characteristic bubble phenomena at various levels of gravity is drawn.Four isostructural dinuclear M2L2 mesocates of the general formula [M2(NCS)4(L)2]·4.5MeOH (1M; M = Mn, Fe, Co, Zn) were constructed by using the coordination-driven self-assembly of the [M(NCS)2] precursor and the flexible bis-bidentate pyridylimine Schiff base ligand L (L = 4,4'-(1,4-phenylenebis(oxy))bis(N-(pyridin-2-ylmethylene)aniline). The centrosymmetric M2L2 mesocate forms through the side-by-side coordination of two L ligands to a pair of M(ii) ions. The mesocates exhibit a reversible temperature induced desolvation-solvation behavior without losing their structural integrity. The activated 1Co, as the representative M2L2 mesocate, shows an exceptionally high MeOH vapour uptake capacity of 481.9 cm3 g-1 (68.8 wt%) at STP with good recyclability. Notably, it also exhibits CO2 adsorption with an uptake capacity of 20.2 cm3 g-1 (3.6 wt%) at room temperature and 1 bar.Metal-organic frameworks (MOFs) are recognized as a class of promising crystalline materials. However, their subsequent processing and shaping still remain a challenge, and one emerging strategy is to hybridize MOFs with flexible polymers. Herein, by utilizing a simple and cost-effective post-synthetic polymerization method, under mild conditions, MOF particles with olefin bonds are covalently linked to polymer chains. Moreover, photoactive europium ions are also introduced into this system during the polymerization process. Importantly, the resulting MOF-based membrane (MOF1-Eu3+@PEMA) is uniform, showing great structural and fluorescence stability against strict conditions (aqueous solutions with pH 0.98-13.11). Besides, given its good luminescence properties, the membrane is employed for the identification of common volatile organic compounds and a selective response to toluene was achieved. Selleck Benzylpenicillin potassium This work accelerates the practical applications of MOF-based membranes and enriches the methods for MOF modification.Covering up to May 2020Oxidosqualene cyclases (OSCs) catalyze one of the most complex polycyclization reactions in nature, using the linear 2,3-oxidosqualene to generate an array of triterpene skeletons in plants. Despite the structural diversity of the products, the protein sequences of plant OSCs are highly conserved, where a few key amino acids could govern the product selectivity. Due to the absence of crystal structures, site-directed mutagenesis and substrate structural modification become key approaches to understand the cyclization mechanism. In this review, 98 mutation sites in 25 plant OSCs have been summarized, and the conserved key residues have been identified by sequence alignment. Structure-function relationships are further discussed. Meanwhile, the substrate selectivity has been summarized to probe the active site cavity of plant OSCs. A total of 77 references are included.The local activation overpotential describes the electrostatic potential shift away from equilibrium at an electrode/electrolyte interface. This electrostatic potential is not entirely satisfactory for describing the reaction kinetics of a mixed ionic-electronic conducting (MIEC) solid-oxide cell (SOC) electrode where charge transfer occurs at the electrode-gas interface. Using the theory of the electrostatic potential at the MIEC-gas interface as an electrochemical driving force, charge transfer at the ceria-gas interface has been modelled based on the intrinsic dipole potential of the adsorbate. This model gives a physically meaningful reason for the enhancement in electrochemical activity of a MIEC electrode as the steam and hydrogen pressure is increased in both fuel cell and electrolysis modes. This model was validated against operando XPS data from previous literature to accurately predict the outer work function shift of thin film Sm0.2Ce0.8O1.9 in a H2/H2O atmosphere as a function of overpotential.Nanoporous graphene is considered the next-generation material for reverse osmosis water desalination providing both high water permeability and almost complete salt rejection. The main problem with graphene is the difficulty of synthesizing membranes with a consistent subnanometer pore size distribution. A recently proposed solution involves processing as-grown graphene oxide (GO) monolayers via a mild temperature annealing pre-treatment causing GO functional groups to cluster into small oxidized islands. A following harsh thermal reduction process creates pores only in the small oxidized regions. However, a suitable relationship between the area of the GO islands and the pore dimension is still missing. Here, we study in detail the effects of such a thermal reduction process on the graphene oxide sheet by means of molecular dynamics simulations, particularly highlighting and analysing the process parameters affecting the final pore area. Besides proving that epoxides represent the most suitable functional group to induce carbon removal and, thus, pore generation in reduced GO, we find a twofold way to achieve control over the pore size tuning the dimension and shape of the initial clustered GO areas or changing the harsh reduction process temperature.