α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were ...α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.展开更多
Objective:To observe the expression level of TNF-α mRNA in rats with hepatic fibrosis induced by dimethylnitrosamine (DMN) and to explore its relationship with collagen metabolism and its diagnostic value for hepatic...Objective:To observe the expression level of TNF-α mRNA in rats with hepatic fibrosis induced by dimethylnitrosamine (DMN) and to explore its relationship with collagen metabolism and its diagnostic value for hepatic fibrosis.Methods: Twenty-five male Wistar rats were randomly divided into normal control group (n=10) and model group (n=15). Model rats were induced by DMN for 4 weeks and at final stage were executed. TNF-α mRNA were detected by RT-PCR and the inflammatory necrosis and collagen deposition in hepatic tissue were observed by HE stain and Sirius red stain. The liver functions were determined by automatic biochemical analytic device. The serum marks of liver fibrosis, such as HA, LN and Ⅳ-C were measured with ELISA and RIA. Results: In this study, the rat model of liver fibrosis induced by DMN was successfully constructed. RT-PCR reveals that TNF-α mRNA expression in control group is lower than that of model group. The liver functions of model group were impaired compared with those of the control group (P<0.01). Semi-quantitive analysis revealed that TNF-α/β-actin of normal rats was 0.39±0.12, while 0.93±0.05 of model rats. The concentration of HA (434.44±98.81 vs 252.9±26.59 ng/ml, P<0.01), LN (70.67±6.32 vs 37.90±5.97 ng/ml, P<0.01) and Ⅳ-C (79.39±10.52 vs 21.40±4.17 ng/ml, P<0.01) were significantly increased in the model group as well. Changes of the indexes were similar to the pathological damage of the liver. Conclusion: The results suggested that activation of TNF-α in liver tissues may be the common pathogenic mechanism of liver fibrosis. TNF-α may be a useful index for the diagnosis of hepatic fibrosis which worthies further investigation.展开更多
The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nick...The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.展开更多
In this review, a recent development of cationic ?-diimine palladium(II) complexes for ethylene polymerization and copolymerization with polar functionalized comonomers was briefly described. First, the polymerization...In this review, a recent development of cationic ?-diimine palladium(II) complexes for ethylene polymerization and copolymerization with polar functionalized comonomers was briefly described. First, the polymerization mechanism for this type of catalysts was discussed. Next, recent advances in ligand design were provided with special focus on the influence of ligand structures on the catalytic polymerization properties. Last, the ethylene homopolymerization and copolymerization with various polar comonomers, especially acrylate and vinyl ethers were summarized.展开更多
基金supported by the National Natural Science Foundation of China(52203016)the USTC Research Funds of the Double First-Class Initiative(YD9990002018)+3 种基金the Overseas Students Innovation and Entrepreneurship Support Program Project of Anhui Province(2021LCX022)the Key R&D Projects in Anhui Province(2022i01020012)the Natural Science Foundation of Hefei(2022039)the Excellent Research and Innovation Team Project of Anhui Province(2022AH010001).
文摘α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.
文摘Objective:To observe the expression level of TNF-α mRNA in rats with hepatic fibrosis induced by dimethylnitrosamine (DMN) and to explore its relationship with collagen metabolism and its diagnostic value for hepatic fibrosis.Methods: Twenty-five male Wistar rats were randomly divided into normal control group (n=10) and model group (n=15). Model rats were induced by DMN for 4 weeks and at final stage were executed. TNF-α mRNA were detected by RT-PCR and the inflammatory necrosis and collagen deposition in hepatic tissue were observed by HE stain and Sirius red stain. The liver functions were determined by automatic biochemical analytic device. The serum marks of liver fibrosis, such as HA, LN and Ⅳ-C were measured with ELISA and RIA. Results: In this study, the rat model of liver fibrosis induced by DMN was successfully constructed. RT-PCR reveals that TNF-α mRNA expression in control group is lower than that of model group. The liver functions of model group were impaired compared with those of the control group (P<0.01). Semi-quantitive analysis revealed that TNF-α/β-actin of normal rats was 0.39±0.12, while 0.93±0.05 of model rats. The concentration of HA (434.44±98.81 vs 252.9±26.59 ng/ml, P<0.01), LN (70.67±6.32 vs 37.90±5.97 ng/ml, P<0.01) and Ⅳ-C (79.39±10.52 vs 21.40±4.17 ng/ml, P<0.01) were significantly increased in the model group as well. Changes of the indexes were similar to the pathological damage of the liver. Conclusion: The results suggested that activation of TNF-α in liver tissues may be the common pathogenic mechanism of liver fibrosis. TNF-α may be a useful index for the diagnosis of hepatic fibrosis which worthies further investigation.
基金supported by the National Key R&D Program of China(2021YFA1501700)Fundamental Research Funds for the Central Universities(WK9990000142).
文摘The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.
基金supported by the National Natural Science Foundation of China(21374108,21304054)the Promotive Research Fund for the Young and Middle-aged Scientists of Shandong Province(BS2012CL018)+2 种基金the Foundation of Qufu Normal University(XJ201212)the Fundamental Research Funds for the Central Universities(WK3450000001)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(LK1424)
文摘In this review, a recent development of cationic ?-diimine palladium(II) complexes for ethylene polymerization and copolymerization with polar functionalized comonomers was briefly described. First, the polymerization mechanism for this type of catalysts was discussed. Next, recent advances in ligand design were provided with special focus on the influence of ligand structures on the catalytic polymerization properties. Last, the ethylene homopolymerization and copolymerization with various polar comonomers, especially acrylate and vinyl ethers were summarized.
