Decaaquabis(μ3‐4‐hydroxypyridine‐2,6‐dicarboxylato)bis(4‐hydroxypyridine‐2,6‐dicarboxylato)tetramanganese(II) 3.34‐hydrate: a new three‐dimensional open metal–organic framework based on a tetranuclear MnII complex of chelidamic acid and undecameric stitching water clusters

4‐Hydroxypyridine‐2,6‐dicarboxylic acid (chelidamic acid, cdaH₃) reacts with MnCl₂·2H₂O in the presence of 2‐amino‐4‐methylpyrimidine in water to afford the tetranuclear title complex, [Mn₄(C₈H₃NO₅)₄(H₂O)₁₀]·3.34H₂O, built through carboxylate bridging. The tetranuclear complex sits on a centre of inversion at (, , ). In the crystal, discrete undecameric (H₂O)_10.34 water clusters (involving both coordinated and uncoordinated water molecules, with one site of an uncoordinated water molecule not fully occupied) assemble these tetranuclear Mn^II complex units via an intricate array of hydrogen bonding into an overall three‐dimensional network. The degree of structuring of the (H₂O)_10.34 supramolecular association of water molecules observed in the present compound, imposed by its environment and vice versa, will be discussed in comparison to that observed for the (H₂O)₁₄ supramolecular clusters in the case of the dinuclear complex [Mn₂(cdaH)₂(H₂O)₄]·4H₂O [Ghosh et al. (2005). Inorg. Chem. 44 , 3856–3862].     

Isoquinoline-mediated S-vinylation and N-vinylation of benzo[d]oxazole-2-thiol and benzo[d]thiazole-2-thiol

An effective route to 5-vinylated and N-vinylated benzo[d]oxazole-2(3H)-thiones and benzo[d]thiazole-2(3H)-thiones is described via reaction of acetylenic esters and benzo[d]oxazole-2-thiol and benzo[d]thiazole-2-thiol in the presence of 15 mol%of isoquinoline.     

Identification and quantification of protein carbonylation using light and heavy isotope labeled Girard's P reagent

Protein carbonyls are one of the most widely studied markers of oxidative stress. Determining increases in the concentration of protein carbonyls known to be associated with neurodegenerative diseases, heart disease, cancer and ageing. Identification of carbonylation sites in oxidized proteins has been a challenge. Even though recent advances in proteomics has facilitate the identification of carbonylation sites in oxidized proteins, confident identification remains a challenge due to the complicated nature of oxidative damage and the wide range of oxidative modifications. Here, we report the development of a multiplexing strategy that facilitates confident carbonylated peptide identification through a combination of heavy and light isotope coding and a multi-step filtering process. This procedure involves (1) labeling aliquots of oxidized proteins with heavy and light forms of Girard's reagent P (GPR) and combining them in a 1:1 ratio along with (2) LC/MS and MALDI-MS/MS analysis. The filtering process uses LC/MS and MALDI-MS/MS data to rule out false positives by rejecting peptide doublets that do not appear with the correct concentration ratio, retention time, tag number, or resolution. This strategy was used for the identification of heavily oxidized transferrin peptides and resulted in identification 13 distinct peptides. The competency of the method was validated in a complex mixture using oxidized transferrin in a yeast lysate as well as oxidized yeast. Twenty-five percent of the peptides identified in a pure oxidized sample of transferrin were successfully identified from the complex mixture. Analysis of yeast proteome stressed with hydrogen peroxide using this multiplexing strategy resulted in identification of 41 carbonylated peptides from 36 distinct proteins. Differential isotope coding of model peptides at different concentrations followed by mixing at different ratios was used to establish the linear dynamic range for quantification of carbonylated peptides using light and heavy forms of GPR.     

Silicon carbide nanocones: Computational analysis of chemical shieldings for pristine and boron/nitrogen decorated models

Density functional theory (DFT) calculations were performed to investigate the electronic and structural properties of pristine and boron/nitrogen (B/N) decorated models of a representative silicon carbide nanocone (SiCNC). The atoms of apexes and tips were differently decorated by B/N atoms to make all possible decorations of the investigated SiCNC. The evaluated parameters by the optimization processes and nuclear magnetic resonance (NMR) calculations indicated that the overall and atomic scale properties of the investigated SiCNCs are significantly dependent on the ways of decorations of Si/C atoms by B/N atoms. The Si/C atoms close to the decorated regions also exhibited notable changes in comparison to the pristine model.     

Performance and characterization of iron-nickel catalysts for light olefin production

A series of x (Fe, Ni)/Al2O3 catalysts (x = 2--12 wt%) were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins. 6 wt%(Fe, Ni)/Al2O3 catalyst was found to be the optimal catalyst for the production of C2--C4 olefins. The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated. The best operational conditions were molar feed ratio H2/CO = 2/1, T = 260 ℃, gas hourly space velocity (GHSV) = 2600 h-1 and the pressure of 3 bar. Characterizations of both precursors and catalysts were carried out using X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscopy (SEM), N2-adsorption-desorption measurement, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).