A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnet...A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnetic resonance （^1H NMR）. The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides＇ intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly （4, 4′-diphenylsulfone dimeramide） （PSD） and poly（4, 4′-di pb enyl dimeramide） （PPDI） are comparable to those of PA 1212.展开更多
Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenu...Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. The results showed that incorporation of Nylon 66 into hydrogenated dimer acid-based Nylon had no significant effect on the glass transition or melting temperatures. However, the crystallization temperature, crystallinity degree and the maximum rate of decomposition temperature from derivative thermogravimetry measurements vary. Mechanical testing data revealed that with increasing Nylon 66 concentrations, the tensile strength of copolymers increased, while the elongation at break point and notched izod impact strength decreased. The physical and mechanical properties of HN-40, HN-50 and HN-60 are similar to those of the current PAl 1, PAl212, and PAlll 1 Nylon products.展开更多
The in vitro inhibitory effect of trihydroxybenzoic acid dimer(TAD) extracted from Trapabispinosd roxb on HeLa cell growth was investigated via the MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diophenyl-tetrazolium bromide] r...The in vitro inhibitory effect of trihydroxybenzoic acid dimer(TAD) extracted from Trapabispinosd roxb on HeLa cell growth was investigated via the MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diophenyl-tetrazolium bromide] reduction method. The morphological changes of HeLa cells were observed by means of an optical microscope and a transmission electron microscope(TEM); the cell circles and apoptosis were detected by a flow cytometer. It was found that TAD can significantly inhibit the growth of Hela cells and can induce the apoptosis of HeLa cells. It was also found that the inhibition to the growth of Hela cells and the induction to the apoptosis of HeLa cells have a dosage-dependent feature. The inhibiting rates of TAD with mass concentrations of 25.000, 12.500 and 6.250 mg/L to the HeLa cell growth were 52.04%, 34.44% and 23.72% after 30 h, respectively, while those with TAD mass concentrations of 100.000, 50.000, 25.000, 12.500, 6.250 and 3.125 mg/L showed positive correlation with a correlation coefficient value of r=0.9859(P<0.01) and a IC_ 50 value of 10.90 mg/L. Observed by means of TEM, the HeLa cells exposed to 25.000, 12.500 and 6.250 mg/L TAD showed apoptosis to various extents, shrinkage of the cell nuclei, condensation and margination of chromatin, and cavitation of mitochondrion. An apoptosis peak was detected via a flow cytometer. It can be drawn from the results that TAD extracted from Trapabispinosd roxb has an evident inhibitory effect on the proliferation of and an inductive effect on the apoptosis of HeLa cells, but has no obvious arrest action towards the cell circles of HeLa cells.展开更多
Salvianolic acid G,a caffeic acid dimer with a novel tetracyclic skeleton was isolated from the roots of Salvia miltiorrhiza.Its structure was elucidated by chemical and spectral analysis,especially by 2D NMR analysis.
AIM: To evaluate the protective effects of lipoic acid-niacin(N2 L) dimers against blue light(BL)-induced oxidative damage to human retinal pigment epithelium(hRPE) cells in vitro.METHODS: h RPE cells were divided int...AIM: To evaluate the protective effects of lipoic acid-niacin(N2 L) dimers against blue light(BL)-induced oxidative damage to human retinal pigment epithelium(hRPE) cells in vitro.METHODS: h RPE cells were divided into a control group(CG), a BL group, an N2 L plus BL irradiation group, an α-lipoic acid(ALA) plus BL group, an ALA-only group, and an N2 L-only group. hRPE cellular viability was detected by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium(MTT) bromide assays, and apoptosis was evaluated by annexin-V-PE/7-AAD staining followed by flow cytometry. Ultrastructural changes in subcellular organelles were observed by transmission electron microscopy. Reactive oxygen species formation was assayed by flow cytometry. The expression levels of the apoptosis-related proteins BCL-2 associated X protein(BAX), B-cell leukmia/lymphoma 2(BCL-2), and caspase-3 were quantified by Western blot analysis.RESULTS: BL exposure with a light density of 4±0.5 mW/cm2 exceeding 6 h caused hRPE toxicity, whereas treatment with a high dose of N2 L(100 mol/L) or ALA(150 mol/L) maintained cell viability at control levels. BL exposure caused vacuole-like degeneration, mitochondrial swelling, and reduced microvillus formation;however, a high dose of N2 L or ALA maintained the ultrastructure of hRPE cells and their organelles. High doses of N2 L and ALA also protected hRPE cells from BL-induced apoptosis, which was confirmed by Western blot analysis: BCL-2 expression significantly increased, while BAX and caspase-3 expression slightly decreased compared to the CG.CONCLUSION: High-dose N2 L treatment(>100 mol/L) can reduce oxidative damage in degenerating hRPE cells exposed to BL with an efficacy similar to ALA.展开更多
In order to improve the toughness of the cured aromatic tetrafunctional epoxy resins,a dimer carboxylic acid named dimer fatty acid(DFA)was used to modify an aromatic tetrafunctional epoxy,N,N,N',N'-tetraglyci...In order to improve the toughness of the cured aromatic tetrafunctional epoxy resins,a dimer carboxylic acid named dimer fatty acid(DFA)was used to modify an aromatic tetrafunctional epoxy,N,N,N',N'-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane(TGBAPP).The curing behaviors of DFATGBAPP/MNA(methyl nadic anhydride)systems were studied by differential scanning calorimetry(DSC)method.And the thermal properties of the cured epoxy resin were investigated with the thermo-gravimetric analysis(TGA)and dynamic mechanical analysis(DMA).Besides,the toughness was characterized with the impact strength tested by charpy impact testing.The results indicated that the modification would improve the curing reactions,and the curing temperatures were decreased with the increasing content of DFA.The thermal properties were not influenced obviously,and the toughness could be improved when the epoxy resin was modified with DFA.展开更多
文摘A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum （FT-IR） and nuclear magnetic resonance （^1H NMR）. The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides＇ intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly （4, 4′-diphenylsulfone dimeramide） （PSD） and poly（4, 4′-di pb enyl dimeramide） （PPDI） are comparable to those of PA 1212.
基金the 863 program(No. 2011AA02A204) for financial support
文摘Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. The results showed that incorporation of Nylon 66 into hydrogenated dimer acid-based Nylon had no significant effect on the glass transition or melting temperatures. However, the crystallization temperature, crystallinity degree and the maximum rate of decomposition temperature from derivative thermogravimetry measurements vary. Mechanical testing data revealed that with increasing Nylon 66 concentrations, the tensile strength of copolymers increased, while the elongation at break point and notched izod impact strength decreased. The physical and mechanical properties of HN-40, HN-50 and HN-60 are similar to those of the current PAl 1, PAl212, and PAlll 1 Nylon products.
文摘The in vitro inhibitory effect of trihydroxybenzoic acid dimer(TAD) extracted from Trapabispinosd roxb on HeLa cell growth was investigated via the MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diophenyl-tetrazolium bromide] reduction method. The morphological changes of HeLa cells were observed by means of an optical microscope and a transmission electron microscope(TEM); the cell circles and apoptosis were detected by a flow cytometer. It was found that TAD can significantly inhibit the growth of Hela cells and can induce the apoptosis of HeLa cells. It was also found that the inhibition to the growth of Hela cells and the induction to the apoptosis of HeLa cells have a dosage-dependent feature. The inhibiting rates of TAD with mass concentrations of 25.000, 12.500 and 6.250 mg/L to the HeLa cell growth were 52.04%, 34.44% and 23.72% after 30 h, respectively, while those with TAD mass concentrations of 100.000, 50.000, 25.000, 12.500, 6.250 and 3.125 mg/L showed positive correlation with a correlation coefficient value of r=0.9859(P<0.01) and a IC_ 50 value of 10.90 mg/L. Observed by means of TEM, the HeLa cells exposed to 25.000, 12.500 and 6.250 mg/L TAD showed apoptosis to various extents, shrinkage of the cell nuclei, condensation and margination of chromatin, and cavitation of mitochondrion. An apoptosis peak was detected via a flow cytometer. It can be drawn from the results that TAD extracted from Trapabispinosd roxb has an evident inhibitory effect on the proliferation of and an inductive effect on the apoptosis of HeLa cells, but has no obvious arrest action towards the cell circles of HeLa cells.
文摘Salvianolic acid G,a caffeic acid dimer with a novel tetracyclic skeleton was isolated from the roots of Salvia miltiorrhiza.Its structure was elucidated by chemical and spectral analysis,especially by 2D NMR analysis.
基金Supported by the Guangzhou Science and Technology Foundation of Guangdong Province (No.2014J4100035 No.2014KP000071)
文摘AIM: To evaluate the protective effects of lipoic acid-niacin(N2 L) dimers against blue light(BL)-induced oxidative damage to human retinal pigment epithelium(hRPE) cells in vitro.METHODS: h RPE cells were divided into a control group(CG), a BL group, an N2 L plus BL irradiation group, an α-lipoic acid(ALA) plus BL group, an ALA-only group, and an N2 L-only group. hRPE cellular viability was detected by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium(MTT) bromide assays, and apoptosis was evaluated by annexin-V-PE/7-AAD staining followed by flow cytometry. Ultrastructural changes in subcellular organelles were observed by transmission electron microscopy. Reactive oxygen species formation was assayed by flow cytometry. The expression levels of the apoptosis-related proteins BCL-2 associated X protein(BAX), B-cell leukmia/lymphoma 2(BCL-2), and caspase-3 were quantified by Western blot analysis.RESULTS: BL exposure with a light density of 4±0.5 mW/cm2 exceeding 6 h caused hRPE toxicity, whereas treatment with a high dose of N2 L(100 mol/L) or ALA(150 mol/L) maintained cell viability at control levels. BL exposure caused vacuole-like degeneration, mitochondrial swelling, and reduced microvillus formation;however, a high dose of N2 L or ALA maintained the ultrastructure of hRPE cells and their organelles. High doses of N2 L and ALA also protected hRPE cells from BL-induced apoptosis, which was confirmed by Western blot analysis: BCL-2 expression significantly increased, while BAX and caspase-3 expression slightly decreased compared to the CG.CONCLUSION: High-dose N2 L treatment(>100 mol/L) can reduce oxidative damage in degenerating hRPE cells exposed to BL with an efficacy similar to ALA.
基金Shanghai Leading Academic Discipline Project,China(No.s30107)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,Chinathe Project of Shanghai Science and Technology Committee,China(No.12520500300)
文摘In order to improve the toughness of the cured aromatic tetrafunctional epoxy resins,a dimer carboxylic acid named dimer fatty acid(DFA)was used to modify an aromatic tetrafunctional epoxy,N,N,N',N'-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane(TGBAPP).The curing behaviors of DFATGBAPP/MNA(methyl nadic anhydride)systems were studied by differential scanning calorimetry(DSC)method.And the thermal properties of the cured epoxy resin were investigated with the thermo-gravimetric analysis(TGA)and dynamic mechanical analysis(DMA).Besides,the toughness was characterized with the impact strength tested by charpy impact testing.The results indicated that the modification would improve the curing reactions,and the curing temperatures were decreased with the increasing content of DFA.The thermal properties were not influenced obviously,and the toughness could be improved when the epoxy resin was modified with DFA.
