The complexation reaction between borate ions and phenol-formaldehyde resol resin in aqueous solution was studied by pH measurement, small model molecules and infrared spectroscopy. The results show that the complexat...The complexation reaction between borate ions and phenol-formaldehyde resol resin in aqueous solution was studied by pH measurement, small model molecules and infrared spectroscopy. The results show that the complexation can proceed completely and rapidly at room temperature. Borate ion attacks phenol hydroxyl groups and adjacent position hydroxymethyl groups on the phenol ring of the resin, and forms the coordinate bond between boron atom in borate ion and oxygen atom in the hydroxyl groups. The complexation is a quantitative reaction. The complex is a six member ring containing two oxygens and one boron. The complexation can release hydrogen ions resulting in the decreasing pH in the resin solution.展开更多
The title complex Co（DMSO）2（H2O）2（SCN）2 has been prepared and structurally characterized. It crystallizes in monoclinic, space group P21/n with a= 5.1981（9）, b = 11.944（2）, c = 12.646（2） A,β = 98.686（2）...The title complex Co（DMSO）2（H2O）2（SCN）2 has been prepared and structurally characterized. It crystallizes in monoclinic, space group P21/n with a= 5.1981（9）, b = 11.944（2）, c = 12.646（2） A,β = 98.686（2）°, V = 776.2（2） A^3, C6H16CoN2O4S4, Mr = 367.38, Z = 2, De = 1.572 g/cm^3, F（000） = 378 and μ（MoKa） = 1.646 mm^-1. The structure was refined to R= 0.0232 and wR = 0.0645 for 1241 observed reflections with I 〉 2σ（I）. In the title complex, each Co（II） atom is octahedrally coordinated by four O atoms from two DMSO ligands and two water molecules as well as two N atoms from SCN^- ions. The title molecules are connected to each other through intermolecular hydrogen bonds to form a 1-D structure extended by eight-membered Co2O4H2 rings.展开更多
New electron donors with hydroxyl groups were synthesized and characterized spectroscopically. Their redox potentials were determined with cyclic voltammetry, and the comparison with BEDT-TTF [Bis(ethylenedithio)tetra...New electron donors with hydroxyl groups were synthesized and characterized spectroscopically. Their redox potentials were determined with cyclic voltammetry, and the comparison with BEDT-TTF [Bis(ethylenedithio)tetrathiafulvalene] in this aspect was made. These results indicated that the new electron donors had similar electron-donating capabilities as BEDT-TTF.展开更多
NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemosele...NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.展开更多
BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting ...BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited. AIM To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress. METHODS C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2- deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation. RESULTS When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation. CONCLUSION The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.展开更多
Oxygen and nitrogen-functionalized carbon nanotubes （OCNTs and NCNTs） were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Tempe...Oxygen and nitrogen-functionalized carbon nanotubes （OCNTs and NCNTs） were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Temperature-programmed desorption, N2 physisorption, Raman spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were employed to characterize the surface properties of OCNTs and NCNTs, aiming at a detailed analysis of the type and amount of oxygen- and nitrogen-containing groups as well as surface defects. The gas-phase treatments applied for oxygen and nitrogen functionalization at elevated temperatures up to 600 ℃ led to the increase of surface defects, but did not cause structural damages in the bulk. NCNTs showed a clearly higher activity than the pristine CNTs and OCNTs in the hydrogenation of 1,5-cyclooctadiene, and also the selectivity to cyclooctene was higher. The favorable catalytic properties are ascribed to the nitrogen-containing surface functional groups as well as surface defects related to nitrogen species. In contrast, oxygen-containing surface groups and the surface defects caused by oxygen species did not show clear contribution to the hydrogenation catalysis.展开更多
Hydrogen peroxide(H2O2)is one of the 100 most important chemicals involved in multiple chemical processes including paper and textile manufacturing,waste degradation,and pharmaceutical production[1].Compared with the ...Hydrogen peroxide(H2O2)is one of the 100 most important chemicals involved in multiple chemical processes including paper and textile manufacturing,waste degradation,and pharmaceutical production[1].Compared with the current industrial process to produce H2O2 following the anthraquinone oxidation/reduction method,electrochemical reduction of oxygen to H2O2 through a two-electron pathway constitutes an environmental friendly alternative route[2-4].Unfortunately,the electrogeneration of H2O2 from two-electron reduction of oxygen feedstock is kinetically sluggish and therefore requires electrocatalysts with high reactivity,high selectivity,and good stability[5,6].展开更多
文摘The complexation reaction between borate ions and phenol-formaldehyde resol resin in aqueous solution was studied by pH measurement, small model molecules and infrared spectroscopy. The results show that the complexation can proceed completely and rapidly at room temperature. Borate ion attacks phenol hydroxyl groups and adjacent position hydroxymethyl groups on the phenol ring of the resin, and forms the coordinate bond between boron atom in borate ion and oxygen atom in the hydroxyl groups. The complexation is a quantitative reaction. The complex is a six member ring containing two oxygens and one boron. The complexation can release hydrogen ions resulting in the decreasing pH in the resin solution.
基金This work was supported by the National Natural Science Foundation of China (No. 50572040)
文摘The title complex Co（DMSO）2（H2O）2（SCN）2 has been prepared and structurally characterized. It crystallizes in monoclinic, space group P21/n with a= 5.1981（9）, b = 11.944（2）, c = 12.646（2） A,β = 98.686（2）°, V = 776.2（2） A^3, C6H16CoN2O4S4, Mr = 367.38, Z = 2, De = 1.572 g/cm^3, F（000） = 378 and μ（MoKa） = 1.646 mm^-1. The structure was refined to R= 0.0232 and wR = 0.0645 for 1241 observed reflections with I 〉 2σ（I）. In the title complex, each Co（II） atom is octahedrally coordinated by four O atoms from two DMSO ligands and two water molecules as well as two N atoms from SCN^- ions. The title molecules are connected to each other through intermolecular hydrogen bonds to form a 1-D structure extended by eight-membered Co2O4H2 rings.
基金the Chinese Academy of Sciences(KJ951-A1-501-03)
文摘New electron donors with hydroxyl groups were synthesized and characterized spectroscopically. Their redox potentials were determined with cyclic voltammetry, and the comparison with BEDT-TTF [Bis(ethylenedithio)tetrathiafulvalene] in this aspect was made. These results indicated that the new electron donors had similar electron-donating capabilities as BEDT-TTF.
文摘NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.
基金Supported by the National Natural Science Foundation of China,No.81503367 and No.81703832
文摘BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited. AIM To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress. METHODS C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2- deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation. RESULTS When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation. CONCLUSION The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.
基金supported by the German Federal Ministry of Education and Research (BMBF) for the CarboKat Project (03X0204D) within the scope of the Inno.CNT Alliance
文摘Oxygen and nitrogen-functionalized carbon nanotubes （OCNTs and NCNTs） were applied as metal-free catalysts in selective olefin hydro- genation. A series of NCNTs was synthesized by NH3 post-treatment of OCNTs. Temperature-programmed desorption, N2 physisorption, Raman spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were employed to characterize the surface properties of OCNTs and NCNTs, aiming at a detailed analysis of the type and amount of oxygen- and nitrogen-containing groups as well as surface defects. The gas-phase treatments applied for oxygen and nitrogen functionalization at elevated temperatures up to 600 ℃ led to the increase of surface defects, but did not cause structural damages in the bulk. NCNTs showed a clearly higher activity than the pristine CNTs and OCNTs in the hydrogenation of 1,5-cyclooctadiene, and also the selectivity to cyclooctene was higher. The favorable catalytic properties are ascribed to the nitrogen-containing surface functional groups as well as surface defects related to nitrogen species. In contrast, oxygen-containing surface groups and the surface defects caused by oxygen species did not show clear contribution to the hydrogenation catalysis.
基金supported by the National Key Research and Development Program (2016YFA0202500 and 2016YFA0200101)the National Natural Science Foundation of China (21676160)Tsinghua University Initiative Scientific Research Program
文摘Hydrogen peroxide(H2O2)is one of the 100 most important chemicals involved in multiple chemical processes including paper and textile manufacturing,waste degradation,and pharmaceutical production[1].Compared with the current industrial process to produce H2O2 following the anthraquinone oxidation/reduction method,electrochemical reduction of oxygen to H2O2 through a two-electron pathway constitutes an environmental friendly alternative route[2-4].Unfortunately,the electrogeneration of H2O2 from two-electron reduction of oxygen feedstock is kinetically sluggish and therefore requires electrocatalysts with high reactivity,high selectivity,and good stability[5,6].
