Impact of prefractionation using Gradiflow on two-dimensional gel electrophoresis and protein identification by matrix assisted laser desorption/ionization-time of flight-mass spectrometry

Prefractionation of protein samples prior to two-dimensional electrophoresis (2-DE) has the potential to increase the dynamic detection range for proteomic analysis. We evaluated a membrane-based electrophoretic separation technique (Gradiflow) for its ability to fractionate an exoproteome sample from the filamentous fungus Trichoderma reesei. The sample was separated on the basis of size and charge. Buffer optimization was found to be necessary for successful size fractionation. Fractionation by charge was used to resolve the sample into four fractions that were subjected to analysis by two-dimensional electrophoresis (2-DE). Enhanced detection of low-abundance proteins with selective removal of high-abundance species was achieved. Fractionated and unfractionated samples were examined for differences in the ability to identify proteins following 2-DE using trypsin in-gel digestion followed by peptide mass fingerprinting using matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Fractionated samples showed marked improvement in protein identification ability and sequence coverage. This study demonstrates the utility of the Gradiflow for fractionation, resulting in an enhancement of resolution and characterization of a moderately complex proteome.     

Intermolecular rhodium-catalyzed [2+2+2] carbocyclization reactions of 1,6-enynes with symmetrical and unsymmetrical alkynes

The crossed intermolecular rhodium-catalyzed [2+2+2] carbocyclization of carbon and heteroatom tethered 1,6-enynes can be accomplished with symmetrical and unsymmetrical alkynes, to afford the corresponding bicyclohexadienes in an efficient and highly selective manner.     

The molecular structure of tetrathiofulvalene-13C (TTF) from proton magnetic resonance studies using nematic solvents

The molecular structure of TTF dissolved in nematic liquid crystalline solvents has been determined from the proton magnetic resonance including couplings due to ¹³C in natural abundance. The molecule is puckered in a boat conformation with the SCHCHS planes making a dihedral angle of 13 ± 2° with the S₂C  CS₂ plane. The other structural parameters obtained are r_CH = 1.085 ± 0.014 Å and the angel CCH = 123.7 ± 1.5°.     

A novel class of amide-derived air-stable P,O-ligands for Suzuki cross-coupling at low catalyst loading

The benzamide-derived P,O-ligands efficiently promoted the Pd-catalyzed Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid at 0.01 mol % of Pd loading at 60-80 °C to form biaryls in excellent yields. A sterically hindered arylboronic acid gave a quantitative yield of the coupling product at 110 °C with 1 mol % Pd.     

生物质裂解产物的制备及HPLC检测其成分的虚拟仿真实验开发

In order to improve university laboratory teaching and practical education under the background of information technology, as well as overcome the difficulty for practical training, develop a virtual simulation experiment platform for rapid pyrolysis of natal materials and high-performance liquid chromatographic (HPLC) detection of its components. The experiment integrates the actual operation process of the plant to produce cleaved products by rapid pyrolysis of biomass with HPLC detection. The virtual experiment is divided into biomass sample pretreatment, rapid biomass pyrolysis, bio-oil extraction, and HPLC determination of complex components, making the biomass cleavage workshop "real" through simulation. This virtual simulation experiment fully integrates the utilization of biomass resources and basic chemistry courses (such as organic chemistry, instrumental analysis, chemical engineering principles, etc.), which are widely involved in agricultural and forestry majors with advantageous characteristics value.     

Trivalent atom contribution on solid-solid transformation of Ga13 polycation intercalated clay into sodalite investigated by X-ray absorption spectroscopy

Solid-solid transformation mechanism of Ga Keggin-type ion intercalated clay into sodalite has been clarified by X-ray diffraction (XRD), FT-IR spectroscopy, and X-rayabsorption spectroscopy (XAS). To follow the structural evolution precisely by XANES and EXAFS, the XAS active element containing polycation [Ga13O4(OH)24(H2O)12]7+ was intercalated into montmorillonite (MMT). FT-IR and XAS spectra confirm that the formation of sodalite framework is initiated by the delocalized rearrangement between silicate networks and collapsed interlayered Ga species, and is followed by the incorporation of Al in the octahedral sheet of clay (MMT). According to the XAS studies, it is found that the formation of Ga(Al)-O-Si species is strongly influenced by the trivalent cations, which are rapidly changed in the environment, followed by reaction with the silicate network of clay during the solid-solid transformation.     

Simultaneous Determination of Oxytetra- cycline, Doxycycline, Tetracycline and Chlortetracycline in Tetracycline Antibiotics by High-Performance Liquid Chromatog- raphy with Fluorescence Detection

A simple, rapid and sensitive high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of oxytetracycline, doxycycline, tetracycline and chlortetracycline was developed, and successfully applied to the analysis of commercial tetracycline antibiotics. The separation was performed on a reverse-phase C₁₈ column with a gradient elution composed of methanol and sodium acetate buffer (containing disodium ethylenediaminetetraacetate and calcium chloride, pH 8.10) as the mobile phase, and fluorescence detection at 532 nm (excitation at 380 nm). The detection limits for oxytetracycline, doxycycline, tetracycline and chlortetracycline were 0.1, 0.5, 0.3 and 0.4 g L^–1, respectively. Data with respect to precision and accuracy were reported and discussed.     

Optimization of zinc phosphate coating on 7075-T6 aluminum alloy

A zinc phosphate coating process on 7075-T6 aluminum alloy has been significantly improved through a combined approach of titanium colloid pretreatment, pH level adjustment, fluoride additive and ZnO/H₃PO₄ ratio adjustment. In particular, optimum phosphate coatings were formed in coating baths with a ZnO/H₃PO₄ ratio of 0.205 and 0.256. Coating morphology studied by SEM reveals that the adjustment in the coating procedure produces an improved crystalline coating layer with high coverage and small grain size. For coatings formed in a bath with a ratio of 0.205, the coverage of the crystalline patches on top of the amorphous coating base is almost complete. The chemical composition of the coating layers has been characterized by XPS and SIMS. The crystalline and amorphous coating phases formed in the bath with a ratio of 0.205 were found to have compositions given schematically as Zn_x(PO₄) and Zn_xAl_y(PO₄), respectively. In contrast, neither coating phase formed in the bath with a ratio of 0.256 shows the presence of Al.     

The ring-closing metathesis of vinyl ethers with Grubbs'' catalyst for the synthesis of dihydropyrans

A series of acyclic vinyl ethers have been prepared and treated with Grubbs' ruthenium catalyst ((Cy₃P)₂RuCl₂=CHPh). Contrary to previous findings, it has been shown that certain vinyl ethers are excellent substrates for the ring closing metathesis with ruthenium based catalysts.