Comparative studies on the binding site of anesthetics to GABA a receptors using in silico docking methods

Although the GABAA receptor(GABAAR)has been proposed as the main action site for sevoflurane,isoflurane,halothane,enflurane,propofol,and benzodiazepines(BZDs),binding of these anesthetics with high-resolution structures of the GABAAR have been rarely examined by comparative docking analyses.Moreover,various combinations of ligands on more GABAARs with various subtypes need to be analyzed to understand the elaborate action mechanism of GABAARs better because some GABAA ligands showed specificity toward the distinct subtypes of the GABAAR.Methods:We performed in silico docking analysis to compare the binding modes of sevoflurane,isoflurane,halothane,enflurane,propofol,and BZDs to the GABAAR based on one of the most recently provided 3D structures.We performed the docking analysis and the affinity-based ranking of the binding sites.Results:Our docking studies revealed that isoflurane,halothane,and enflurane docked in an extracellular domain(ECD)on GABAARs,in contrast to sevoflurane.Conclusion:Our results supported a multi-site mechanism for the allosteric modulation of propofol.Propofol was bound to the pore or favored various subsites in the transmembrane domain(TMD).Our result confirmed that different chemically related BZD ligands interact via distinct binding modes rather than by using a common binding mode,as previously suggested.

Dodecylamine Derivative of Hydroxocobalamin Acts as a Potent Inhibitor of Cobalamin-Dependent Methionine Synthase in Mammalian Cultured COS-7 Cells

We evaluated whether the dodecylamine derivative of hydroxocobalamin acts as a potent inhibitor of cobalamin-dependent enzymes in an African green monkey kidney cell, COS-7. When the dodecylamine derivative (1.0 μmol/L) did not show any cytotoxicity in the cultured cells, the derivative could not affect methylmalonyl-CoA mutase (holo-enzyme) activity, but significantly inhibit methionine synthase (holo-enzyme) activity in the cell homogenates of COS-7 grown in 1.0 μmol/L hydroxocobalamin-supplemented medium. An immunoblot analysis indicated that the dodecylamine derivative could not decrease the protein level of methionine synthase, but significantly inhibit the enzyme activity.

Determination of Vitamin B₁₂in Chinese Black Tea Leaves

We determined vitamin B12 content of Chinese black tea leaves using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.25 - 0.69 μg/100g dry weight) of vitamin B12 were detected in Pu’er, Fu, and Brick tea leaves. However, vitamin B12 content (0.06 - 1.37 μg/100g dry weight) of Ryubao tea leaves significantly varied. To determine whether Chinese black tea leaves contain vitamin B12 or other corrinoid compounds that are inactive in humans, corrinoid compounds were purified from Ryubao tea by an immunoaffinity column chromatography and vitamin B12 was identified by liquid chromatography-electrospray ionization/tandem mass spectrometry. Vitamin B12 content in the tea drink prepared from Ryubao tea leaves was very low (0.8 ng/100mL). Our results indicate that Chinese black tea is usually not a good source of B12, although Ryubao tea leaves with the highest B12 content may be utilized as a source of this vitamin for vegerarians.

Inherent mass transfer engineering of a Co,N co-doped carbon material towards oxygen reduction reaction

Oxygen reduction reaction (ORR) is an important process for the conversion and utilization of a wide range of renewable energy sources, and is critical for the shape of future energy scenario [1–10]. However, ORR is a complex four-electron transfer process and is kinetically sluggish. It is urgent to develop high-efficient electrocatalysts to solve this problem [11–15]. Up to now, precious metal-based catalysts such as Pt-based electrocatalysts have been widely studied and found to be one of the most efficient electrocatalysts for ORR. However, the high price and the small reserves limit their large-scale commercialization [10,16–23]. Therefore, in order to fulfill needs for the practical applications, it is necessary to develop low-cost electrocatalysts, also with high activity and great stability [19,24–28].

The critical role of bulk density of graphene oxide in tuning its defect concentration through microwave-driven annealing

Controlling the concentration of defects in reduced graphene oxide （rGO） to tailor its electrical and physicochemical properties has remained a significant challenge. We report that extent of microwave （MW）-driven annealing of rGO is influenced significantly by its bulk density, which allows us to vary its defect density and crystallite size over wide ranges by controlling this parameter. Extent of anneal- ing was investigated by multiple techniques including Raman and X-ray photoelectron spectroscopies, and electrical conductivity measurements. Improved corrosion resistance of rGOs upon annealing was ex- amined by cyclic voltammetry in H_2SO_4 electrolyte and temperature-programmed oxidation of rGO. Our results indicate that a low bulk density of rGO facilitates defect annealing, yielding high-quality carbon with 99.3 wt% purity, oxidative resistance as high as graphite powder, and an electrical conductivity of 36,000 S m-1 in the compressed powder form. These results demonstrate a prospective synthesis route for tailor-made nanocarbons from rGO through MW-driven annealing.

Occurrence of Biologically Inactive Corrinoid Compounds in Canned Edible Apple Snails (Escargots)

In this study, we characterized and quantified vitamin B12 in canned apple snails, escargots, (boiled plain) using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Vitamin B12 contents of canned escargots (boiled plain) were varied from approximately 0.8 μg/100g weight to approximately 5.5 μg/100g weight (mean values, 2.2 μg/100g weight). We identified vitamin B12 compounds from escargots using liquid chromatography-electrospray ionization/tandem mass spectrometry. We found that escargots contained true vitamin B12 and two inactive corrinoids, which were identified as factor IIIm (or methoxymensimidazolyl cyanocobamide), and factor S (or 2-methylmercaptoadenyl cyanocobamide). These results indicate that canned escargots (boiled plain) are not good sources of vitamin B12 for humans.

Characterization of Corrinoid Compounds in the Edible Cyanobacterium <i>Nostoc flagelliforme</i>the Hair Vegetable

Vitamin B12 contents in the edible cyanobacterium Nostoc flagelliforme, also known as hair vegetable, were assayed using a microbiological method. We detected high vitamin B12 contents in samples of naturally grown cells (109.2 ± 18.5 μg/100g dry weight) and cultured cells (120.2 ± 53.6 μg/100g dry weight). However, commercially available hair vegetable samples, which comprised fake substitutes and Nostoc, had variable contents (4.8 - 101.6 μg/100g dry weight) because concomitant fake items contain very low vitamin B12 contents. To evaluate whether natural and cultured N. flagelliforme samples contained vitamin B12 or pseudovitamin B12, corrinoid compounds were purified and identified as pseudovitamin B12 (approximately 72%) and vitamin B12 (approximately 28%) using silica gel 60 TLC bioautography and LC/MS. The results suggested that N. flagelliforme contains substantial amounts of pseudovitamin B12, which is inactive in humans.

Ni(acac)_(2)Mediated Vinyl Polymerization of Norbornene in the Presence of Bulky Salicylaldiminate Ligands:An Effective Strategy to Access Soluble Polynorbornenes

Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.

Chain-Length-Dependent Hydrogen-Bonded Self-Assembly of Terminally Functionalized Discrete Polyketones

Here,we report the synthesis and the chain-lengthdependent self-assembling behaviors of discrete di-,tetra-,and hexaketones terminally functionalized with hydrogen-bonding carboxyl(C1,C2,and C3)and 3-acylaminopyridine groups(P1,P2,and P3).These polyketones were prepared by the coupling reactions of silylated analogues of 3,3-dimethylpentane-2,4-dione and t-butyl 2,2-dimethyl-3-oxobutanoate and the subsequent hydrolysis or amidation with 3-aminopyridine.Single-crystal Xray diffraction analysis revealed that C1 and C2 form helical assemblies in which the components are connected by the dimerization of terminal carboxyl groups,whereas the longer C3 showed infinite hydrogen-bonded chains mediated by 1,4-dioxane used as a crystallization solvent.Pyridine-terminated P1 exhibited a three-dimensional hydrogen-bonded network owing to multiple NH…N(pyridine)hydrogen bonds in the solid state.P2 generated a double-helix-like fiber structure in the crystalline state.Among the pyridine-terminated polyketones P1−P3,only P2 showed gelation behavior in chloroform(100 mM concentration)at 25℃.The scanning electron microscopy measurement of xerogel P2 revealed the formation of rod-like structures with a thickness of approximately 0.5−3.5μm.These results demonstrate that the precise control of the polyketone chain length can significantly alter hydrogen-bonded self-assembly in the solid state and in solution even with the same terminal structures.

Facile and Scalable Synthesis of a Highly Hydroxylated Water-Soluble Fullerenol as a Single Nanoparticle

水溶性的 polyhydroxylated fullerene，即 fullerenol 与 44 个氢氧根组和 8 个第二等的界限水分子一起， C60 (哦)

One-Pot Room-Temperature Synthesis of Mg Containing MCM-41 Mesoporous Silica for Aldol Reactions

One-pot synthesis of Mg containing MCM-41(Mg-MCM-41) materials was respectively carried out by a room temperature(RT) method and a hydrothermal(HT) method for aldol condensation of 4-nitrobenzaldehyde and acetone and self-condensation of acetone. The RT method can prepare MCM-41 materials containing large amounts of Mg while maintaining the structural characteristics of MCM-41 even at very low Si/Mg ratios(large Mg loadings), but the HT method cannot. The RT method can also give more active catalysts than the HT method, because the catalysts prepared by the RT method are more basic than those prepared by the HT one. The characterization indicates that Mg atoms in the Mg-MCM-41 prepared by the RT method exist as MgO disperses well on the wall surface of pores, while those in Mg-MCM-41 prepared by the HT method are included in the bulk with a smectite-like structure.

Combustion synthesis of YAG:Ce phosphors via the thermite reaction of aluminum

Cerium-doped yttrium aluminum garnet（YAG：Ce） as a yellow phosphor for white light-emitting diodes（LEDs） was synthesized via a facile combustion method using Y2 O3, CeO2, Al2 O3, Al,and NaClO4 as raw materials. The combustion synthesis approach utilizes the strong exothermic oxidation of aluminum to realize a self-sustaining reaction. In this study, we investigated the effects of the ratios of Al2 O3 to AI,fluxes, and coprecipitated materials as raw materials on the luminescence properties of the synthesized YAG：Ce phosphors. When the amount of Al2 O3 x is varied, the combustion reaction proceeds at x ≤ 1.8,with x = 1.725 being the optimum condition for producing a high-performance product. When 5 wt%BaF2 is added, the luminescence intensity is significantly improved owing to a decrease of YAP（YAlO3）formation with improved uniformity. However, the addition of CaF2 and NaF does not improve the luminescence properties. To suppress the segregation of CeO2, we used the coprecipitated material Y2 O3-CeO2 as a raw material. Unlike with separate addition of Y2 O3 and CeO2, Ce ions are uniformly distributed in the coprecipitated material, resulting in improved luminescence properties. The combination of BaF2 and coprecipitated material significantly improves the internal quantum efficiency to83.0%, which is close to that of commercial phosphors.

Highly Efficient and Thermal Robust Cobalt Complexes for 1,3-Butadiene Polymerization

A family of highly bulky bis(salicylaldiminate)Co(Ⅱ)complexes bearing cavity-like conformations are disclosed herein.Due to their unique bulky nature around the cobalt atoms that are reflected from space-filling models and the buried volume percentages,obviously longer bond distances of Co―N and Co―O are revealed from those complexes.Moreover,because of these well-protected active species,the cobalt complexes are able to catalyze 1,3-butadiene polymerization in high yields at extreme low catalyst concentrations,revealing a ultra high catalytic efficiency.At a ratio of 50000,all the complexes can afford polybutadiene with yields higher than 90%.Furthermore,the highly steric bulkiness of the ligand can also significantly enhance the thermostability of the active species.At temperature of 80-120°C,the complexes are able to successfully maintain high activities,giving polymer yields up to 90%.

Two-Dimensional Metal-Organic Frameworks with Unique Oriented Layers for Oxygen Reduction Reaction:Tailoring the Activity through Exposed Crystal Facets

As one of the most important families of porous materials,metal–organic frameworks(MOFs)have well-defined atomic structures.This provides ideal models for investigating and understanding the relationships between structures and catalytic activities at the molecular level.However,the active sites on the edges of two-dimensional(2D)MOFs have rarely been studied,as they are less exposed to the surfaces.Here,for the first time,we synthesized and observed that the 2D layers could align perpendicular to the surface of a 2D zeolitic imidazolate framework L(ZIF-L)with a leaf-like morphology.Owing to this unique orientation,the active sites on the edges of the 2D crystal structure could mostly be exposed to the surfaces.Interestingly,when another layer of ZIF-L-Co was grown heteroepitaxially onto ZIF-L-Zn(ZIF-L-Zn@ZIF-L-Co),the two layers shared a common b axis but rotated by 90°in the ac plane.This demonstrated that we could control exposed facets of the 2D MOFs.The ZIF-L-Co with more exposed edge active sites exhibited high electrocatalytic activity for oxygen reduction reaction.This work provides a new concept of designing unique oriented layers in 2D MOFs to expose more edge-active sites for efficient electrocatalysis.