Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity ag...Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.展开更多
The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and...The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and Cu_(2)O/Ni O/NF electrodes via in situ pulsed laser irradiation in liquids(PLIL)for the bifunctional electrocatalysis of oxygen evolution reaction(OER)and furfural oxidation reaction(FOR),respectively.Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu_(2)O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR.CoO/NiO/NF electrocatalyst provides a consistently low overpotential of~359 m V(OER)at 10 m A/cm^(2),achieving the maximum FA yield(~16.37 m M)with 61.5%selectivity,79.5%carbon balance,and a remarkable Faradaic efficiency of~90.1%during 2 h of FOR at 1.43 V(vs.reversible hydrogen electrode).Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates(NiOOH and CoOOH)as surface-active centers during electrochemical oxidation.The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products.This method holds promise for large-scale applications,enabling simultaneous production of renewable building materials and fuel.展开更多
O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expre...O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expression and methylation levels in the early embryo and in different embryonic stages, as well as the relationship between MGMT and neural tube defects. Spina bifida aperta was induced in rats by a single intragastric administration of all-trans retinoic acid on embryonic day(E) 10, whereas normal control rats received the same amount of olive oil on the same embryonic day. DNA damage was assessed by detecting γ-H2 A.X in spina bifida aperta rats. Real time-polymerase chain reaction was used to examine mRNA expression of MGMT in normal control and spina bifida aperta rats. In normal controls, the MGMT mRNA expression decreased with increasing embryonic days, and was remarkably reduced from E11 to E14, reaching a minimum at E18. In the spina bifida aperta model, γ-H2 A.X protein expression was increased, and mRNA expression of MGMT was markedly decreased on E14, E16, and E18. Bisulfite sequencing polymerase chain reaction for MGMT promoter methylation demonstrated that almost all CpG sites in the MGMT promoter remained unmethylated in both spina bifida aperta rats and normal controls, and there was no significant difference in methylation level between the two groups on either E14 or E18. Our results show that DNA damage occurs in spina bifida aperta rats. The mRNA expression of MGMT is downregulated, and this downregulation is independent of promoter DNA methylation.展开更多
Dopamine (DA) exposure at a dose of 100 pmol/L for 24 hours causes oxidative stress in SH-SY5Y cells with induction of neuronal differentiation by retinoic acid (RA,10 pmol/L,72 hours) followed by phorbol ester 12...Dopamine (DA) exposure at a dose of 100 pmol/L for 24 hours causes oxidative stress in SH-SY5Y cells with induction of neuronal differentiation by retinoic acid (RA,10 pmol/L,72 hours) followed by phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA,80 nmol/L,72 hours). However,it remains unclear whether the alteration of phenotype observed in response to oxidative stress is associated with protein regulation in this cellular model for Parkinson's disease. The present study detected protein regulation affected by oxidative stress at a proteomic level:selection of differentially altered proteins using two dimensional difference in-gel electrophoresis and identification of these proteins using matrix assisted laser desorption/ionization time-of-flight mass spectrometry. The results demonstrated significant alterations in expression of six proteins in SH-SY5Y cells following the differentiation and fourteen proteins in the differentiated cells following the exposure,exemplified by an increase of tubulin alpha1 in the former but a decrease of tubulin alpha-ubiquitous chain in the latter. These results suggest that two potentially specific but relevant patterns of proteomic change may be produced in SH-SY5Y cells with the induction of differentiation by RA followed by TPA,and in the differentiated cells after DA exposure.展开更多
The 1,10 phenan throline aromatic carboxylic acid(benzoic acid and o phthalic acid) binary and ternary complexes of europium were synthesized.The fluorescence and FT IR spectroscopy,elemental analysis,UV spectroscopic...The 1,10 phenan throline aromatic carboxylic acid(benzoic acid and o phthalic acid) binary and ternary complexes of europium were synthesized.The fluorescence and FT IR spectroscopy,elemental analysis,UV spectroscopic studies on these complexes were also performed.These complexes can emit strong red fluorescence of Eu? excited by UV light.At the same excited wavelength,the fluorescence spectra of the complexes were also studied.The results indicated that the fluorescence intensities of ternary complexes are stronger than that of binary complexes.The reason is that phenanthroline has higher electron density and higher orbit scope in the conjugated system and consequently an easier energy transfer to the europium ion,which makes the fluorescence intensity of ternary complexes be stronger than that of binary complexes.展开更多
Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a ...Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).展开更多
Glyoxylic acid (5 mol%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH- benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted alde...Glyoxylic acid (5 mol%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH- benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields (85-95%) using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster (20--40 rain) reactions and excellent yields of products.展开更多
For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different proces...For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different processing time. Breaking force and water contact angle were tested. Surface changes before and after surface modifications were tested with scanning electron microscopy(SEM). Furthermore,differential scanning calorimeter(DSC) and Fourier transform infrared spectrometry(FTIR) were used to analyze the changes of molecular structure and functional group. Experimental results showed that 6 min was the most suitable time for improving hydrophilicity of PGA filament and preserving its mechanical properties.展开更多
Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strengt...Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strength as the same time. PGA fibers are dipped in H_2O_2 solution a certain time for modification. Scanning electron microscopy( SEM) was used to observe the surface morphology of PGA fibers before and after modification. The varying of PGA macromolecule was examined with Fourier transform infrared spectroscopy( FTIR) analyses. X-ray diffraction( XRD) and differential scanning calorimetry( DSC) analysis showed that crystallinity slightly decreases. Mechanical performance test showed tensile force of modified PGA fiber was increased. The water contact angle test indicated the improving of hydrophilic. A cell proliferation assay showed that fibroblast cells attach and proliferate well on the fibers, which meant the modified fibers possess good cytocompatibility. These results suggest that H_2O_2 surface modification is easy to operate and a advantageous modification method for PGA fibers.展开更多
pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horiz...pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horizon samples from 126 and 98 soil profiles (0 - 120 cm in depth) surveyed from 2014 to 2015 in Guangxi and Yunnan were used to establish the optimal correlation model between pHKCl and pHH2O. The results showed that: 1) pHKCl is lower than pHH2O, pHKCl?was 0.07 - 1.99 units with a mean of 0.99 units lower than for Guangxi, while 0.03 - 1.90 units with a mean of 0.89 lower than pHH2O?for Yunan. 2) There is significant positive correlation between pHKCl?and pHH2O, the optimal correlation models between pHKCl?(y) and pHH2O?(x) for Guangxi and Yunnan are y = 0.1963x2 −1.0512x + 4.338, R2 = 0.836, p 0.1859x, R2 = 0.769, p pHKCl?with exchangeable H+ and Al3+ (R2 = 0.487, 0.716, p pHKCl?is dominated by exchangeable Al3+, followed by exchangeable H+, and their contribution to pHKCl?were 71.1% and 28.7%, respectively.展开更多
The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH an...The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH and interferents on the response current of biosensors based on POAP.展开更多
Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyr...Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.展开更多
olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB...olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB)_2 with a high yieldwas synthesized very conveniently compared witb the solution phase method. Thekinetic behavior was studied by means of the isothermal electrical conductivity mea-surement. The reactivity was found to decrease in the order : Cu(OAc)_2· H_2O>Cu(OAc)_2>Cu (HCOO)_2 ·4H_2O>Cu (HCOO)_2, which was attributable to the crystalstructures of the copper salts.展开更多
Nitrous acid, HNO2, is an important precursor of OH radicals in the troposphere. Measurements of HNO2 and NO2, using differential optical absorption spectroscopy (DOAS), were performed in Shanghai, China for a perio...Nitrous acid, HNO2, is an important precursor of OH radicals in the troposphere. Measurements of HNO2 and NO2, using differential optical absorption spectroscopy (DOAS), were performed in Shanghai, China for a period from October 22, 2004 to January 4, 2005. The mean (and median) hourly concentrations of HNO2 and NO2 during this period were 1.1 (0.7) ppb and 24 (21.4) ppb respectively. A correlation between HNO2/NO2 and PM10 mass concentrations was obtained. This correlation suggests that significant heterogeneous chemical production of HNO2 may occur through NO2 reactions on aerosol surfaces. This hypothesis was further supported by detailed analysis of selected pollution episodes in this study. At the same time, the water dependence of HNO2 formation was studied by analysis of relative humidity (RH). It showed that the maximum HNO2/NO2 ratio was increased along with RH below 70% and inhibited at RH〉70%.展开更多
The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, ...The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the GGA/PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Two possible reaction pathways were investigated in this study. The result indicates that the reaction Re→TS1→IM1→TSA2→IMA2→TSA3→IMA3→TSA4→IMA4→TSA5→P2 is the main pathway, the activation energy of which is the lowest. Re→TS1→IM1 is the rate-limiting step, with the activation energy being 221.54 kJ·mol;and the reaction heat being 10.06 kJ·mol;. The dominant product predicted theoretically is in agreement with the experiment results.展开更多
The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and produc...The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G(d, p) level. Vibration analysis was carried out to confirm its identity as transitions' structure, and the intrinsic reaction coordinate method(IRC) was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.展开更多
Salicylic acid (SA) was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H...Salicylic acid (SA) was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2+ (0, 0.05, 0.15, 0.25 mmol/L) for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA (treated with 0.1 mmol/L SA for 48 h before Pb stress) partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase (SOD), repressing the activity of catalase (CAT) and ascorbate peroxidase (APX) depending on the concentrations of Pb^2+ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity.展开更多
基金supported by National Natural Science Foundation of China(31972021)R&D Projects in Key Areas of Guangdong Province(2019B020212003)+4 种基金the Science and Technology Program of Guangzhou,China(202206010177)Guangdong key research and development program(2021B0202060001)Foshan and agricultural academy cooperation projectGuangdong Modern Agriculture project(2022KJ117)Aquatic Products Center Project of GAAS。
文摘Escherichia coli O157:H7 is one of the major foodborne pathogenic bacterial that cause infectious diseases in humans.The previous found that a combination of kojic acid and tea polyphenols exhibited better activity against E.coli O157:H7 than using either alone.This study aimed to explore responses underlying the antibacterial mechanisms of kojic acid and tea polyphenols from the gene level.The functional enrichment analysis by comparing kojic acid and tea polyphenols individually or synergistically against E.coli O157:H7 found that acid resistance systems in kojic acid were activated,and the cell membrane and genomic DNA were destructed in the cells,resulting in“oxygen starvation”.The oxidative stress response triggered by tea polyphenols inhibited both sulfur uptake and the synthesis of ATP,which affected the bacteria's life metabolic process.Interestingly,we found that kojic acid combined with tea polyphenols hindered the uptake of iron that played an essential role in the synthesis of DNA,respiration,tricarboxylic acid cycle.The results suggested that the iron uptake pathways may represent a novel approach for kojic acid and tea polyphenols synergistically against E.coli O157:H7 and provided a theoretical basis for bacterial pathogen control in the food industry.
基金supported by the Korea Basic Science Institute(National research Facilities and Equipment Center)grant funded by the Ministry of Education(2019R1A6C1010042,2021R1A6C103A427)the financial support from the National Research Foundation of Korea(NRF)(2022R1A2C2010686,2022R1A4A3033528,2021R1I1A1A01060380,2021R1C1C2010726,2019H1D3A1A01071209)。
文摘The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and Cu_(2)O/Ni O/NF electrodes via in situ pulsed laser irradiation in liquids(PLIL)for the bifunctional electrocatalysis of oxygen evolution reaction(OER)and furfural oxidation reaction(FOR),respectively.Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu_(2)O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR.CoO/NiO/NF electrocatalyst provides a consistently low overpotential of~359 m V(OER)at 10 m A/cm^(2),achieving the maximum FA yield(~16.37 m M)with 61.5%selectivity,79.5%carbon balance,and a remarkable Faradaic efficiency of~90.1%during 2 h of FOR at 1.43 V(vs.reversible hydrogen electrode).Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates(NiOOH and CoOOH)as surface-active centers during electrochemical oxidation.The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products.This method holds promise for large-scale applications,enabling simultaneous production of renewable building materials and fuel.
基金supported by the National Natural Science Foundation of China,No.81671469,81171072(to ZWY)the National Basic Research Program of China(973 Program),No.2013CB945402(to ZWY)the Program for Liaoning Innovative Research Team in University of China,No.LT2013016(to ZWY)
文摘O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expression and methylation levels in the early embryo and in different embryonic stages, as well as the relationship between MGMT and neural tube defects. Spina bifida aperta was induced in rats by a single intragastric administration of all-trans retinoic acid on embryonic day(E) 10, whereas normal control rats received the same amount of olive oil on the same embryonic day. DNA damage was assessed by detecting γ-H2 A.X in spina bifida aperta rats. Real time-polymerase chain reaction was used to examine mRNA expression of MGMT in normal control and spina bifida aperta rats. In normal controls, the MGMT mRNA expression decreased with increasing embryonic days, and was remarkably reduced from E11 to E14, reaching a minimum at E18. In the spina bifida aperta model, γ-H2 A.X protein expression was increased, and mRNA expression of MGMT was markedly decreased on E14, E16, and E18. Bisulfite sequencing polymerase chain reaction for MGMT promoter methylation demonstrated that almost all CpG sites in the MGMT promoter remained unmethylated in both spina bifida aperta rats and normal controls, and there was no significant difference in methylation level between the two groups on either E14 or E18. Our results show that DNA damage occurs in spina bifida aperta rats. The mRNA expression of MGMT is downregulated, and this downregulation is independent of promoter DNA methylation.
基金the Science and Technology Development Program of Jilin Province, No. 200505200the Distinguished Professor Foundation of Jilin University, No. 450011011204
文摘Dopamine (DA) exposure at a dose of 100 pmol/L for 24 hours causes oxidative stress in SH-SY5Y cells with induction of neuronal differentiation by retinoic acid (RA,10 pmol/L,72 hours) followed by phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA,80 nmol/L,72 hours). However,it remains unclear whether the alteration of phenotype observed in response to oxidative stress is associated with protein regulation in this cellular model for Parkinson's disease. The present study detected protein regulation affected by oxidative stress at a proteomic level:selection of differentially altered proteins using two dimensional difference in-gel electrophoresis and identification of these proteins using matrix assisted laser desorption/ionization time-of-flight mass spectrometry. The results demonstrated significant alterations in expression of six proteins in SH-SY5Y cells following the differentiation and fourteen proteins in the differentiated cells following the exposure,exemplified by an increase of tubulin alpha1 in the former but a decrease of tubulin alpha-ubiquitous chain in the latter. These results suggest that two potentially specific but relevant patterns of proteomic change may be produced in SH-SY5Y cells with the induction of differentiation by RA followed by TPA,and in the differentiated cells after DA exposure.
文摘The 1,10 phenan throline aromatic carboxylic acid(benzoic acid and o phthalic acid) binary and ternary complexes of europium were synthesized.The fluorescence and FT IR spectroscopy,elemental analysis,UV spectroscopic studies on these complexes were also performed.These complexes can emit strong red fluorescence of Eu? excited by UV light.At the same excited wavelength,the fluorescence spectra of the complexes were also studied.The results indicated that the fluorescence intensities of ternary complexes are stronger than that of binary complexes.The reason is that phenanthroline has higher electron density and higher orbit scope in the conjugated system and consequently an easier energy transfer to the europium ion,which makes the fluorescence intensity of ternary complexes be stronger than that of binary complexes.
基金Supported by the National Natural Science Foundation of China(21476065)the China National Tobacco Corporation
文摘Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).
基金Head,Department of Chemistry,Vinayakrao Patil Mahavidyala Vaijapur 423701(M.S.),India,for partial support of this work.
文摘Glyoxylic acid (5 mol%) performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH- benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields (85-95%) using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster (20--40 rain) reactions and excellent yields of products.
基金Shanghai Municipality Science and Technology Commission,China(No.12DZ1940300)
文摘For improving its hydrophilicity and biocompatibility,and preserving filament mechanical properties at the same time,polyglycolic acid( PGA) filament was modified by potassium dichromate solution with different processing time. Breaking force and water contact angle were tested. Surface changes before and after surface modifications were tested with scanning electron microscopy(SEM). Furthermore,differential scanning calorimeter(DSC) and Fourier transform infrared spectrometry(FTIR) were used to analyze the changes of molecular structure and functional group. Experimental results showed that 6 min was the most suitable time for improving hydrophilicity of PGA filament and preserving its mechanical properties.
基金Shanghai Science and Technical Committee,China(No.10411953300)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,China(No.LZ0902)Minhang District Industry-Study-Research Cooperation,China(No.2012MH202)
文摘Hydrogen peroxide( H_2O_2) is applied for surface modification of polyglycolic acid( PGA) fibers in order to enhance the hydrophilicity and cytocompatibility of PGA fibers effectively,and maintain the breaking strength as the same time. PGA fibers are dipped in H_2O_2 solution a certain time for modification. Scanning electron microscopy( SEM) was used to observe the surface morphology of PGA fibers before and after modification. The varying of PGA macromolecule was examined with Fourier transform infrared spectroscopy( FTIR) analyses. X-ray diffraction( XRD) and differential scanning calorimetry( DSC) analysis showed that crystallinity slightly decreases. Mechanical performance test showed tensile force of modified PGA fiber was increased. The water contact angle test indicated the improving of hydrophilic. A cell proliferation assay showed that fibroblast cells attach and proliferate well on the fibers, which meant the modified fibers possess good cytocompatibility. These results suggest that H_2O_2 surface modification is easy to operate and a advantageous modification method for PGA fibers.
文摘pHKCl and pHH2O are two basic necessary indexes to reflect the acidity of asoil. Predicting pHKCl?directly from pHH2O?could save the cost of laboratory work. In this study, the values of pHKCl and of 442 and 310 horizon samples from 126 and 98 soil profiles (0 - 120 cm in depth) surveyed from 2014 to 2015 in Guangxi and Yunnan were used to establish the optimal correlation model between pHKCl and pHH2O. The results showed that: 1) pHKCl is lower than pHH2O, pHKCl?was 0.07 - 1.99 units with a mean of 0.99 units lower than for Guangxi, while 0.03 - 1.90 units with a mean of 0.89 lower than pHH2O?for Yunan. 2) There is significant positive correlation between pHKCl?and pHH2O, the optimal correlation models between pHKCl?(y) and pHH2O?(x) for Guangxi and Yunnan are y = 0.1963x2 −1.0512x + 4.338, R2 = 0.836, p 0.1859x, R2 = 0.769, p pHKCl?with exchangeable H+ and Al3+ (R2 = 0.487, 0.716, p pHKCl?is dominated by exchangeable Al3+, followed by exchangeable H+, and their contribution to pHKCl?were 71.1% and 28.7%, respectively.
文摘The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH and interferents on the response current of biosensors based on POAP.
文摘Conductive polyacrylonitrile fibers were prepared by electroless copper plating under weak alkaline conditions,with L-ascorbic acid as reducing agent.The influences of CuSO_(4)·5H_(2)O,L-ascorbic acid,2,2′-bipyridine and K_(4)Fe(CN)_(6) concentration on the conductivity and mass gain percentage of the fibers were studied.The morphological structure of the fibers was characterized by scanning electron microscopy(SEM),and the mechanical properties of the fibers were analyzed through the mechanical property test.The results showed that the optimal reaction conditions were as follows:26 g/L CuSO_(4)·5H_(2)O,26 g/L L-ascorbic acid,12 mg/L 2,2′-bipyridine,7 mg/L K 4Fe(CN)6,and 38℃.The volume resistivity of the conductive PAN fibers prepared by the process was only 3.84×10^(-3)Ω·cm.
文摘olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB)_2 with a high yieldwas synthesized very conveniently compared witb the solution phase method. Thekinetic behavior was studied by means of the isothermal electrical conductivity mea-surement. The reactivity was found to decrease in the order : Cu(OAc)_2· H_2O>Cu(OAc)_2>Cu (HCOO)_2 ·4H_2O>Cu (HCOO)_2, which was attributable to the crystalstructures of the copper salts.
基金The National Natural Science Foundation of China (No. 20277006) and the Fudan University Foundation for Young Scientists (No.EXH 6286301)
文摘Nitrous acid, HNO2, is an important precursor of OH radicals in the troposphere. Measurements of HNO2 and NO2, using differential optical absorption spectroscopy (DOAS), were performed in Shanghai, China for a period from October 22, 2004 to January 4, 2005. The mean (and median) hourly concentrations of HNO2 and NO2 during this period were 1.1 (0.7) ppb and 24 (21.4) ppb respectively. A correlation between HNO2/NO2 and PM10 mass concentrations was obtained. This correlation suggests that significant heterogeneous chemical production of HNO2 may occur through NO2 reactions on aerosol surfaces. This hypothesis was further supported by detailed analysis of selected pollution episodes in this study. At the same time, the water dependence of HNO2 formation was studied by analysis of relative humidity (RH). It showed that the maximum HNO2/NO2 ratio was increased along with RH below 70% and inhibited at RH〉70%.
基金Supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ1601215)the Ministry of Education "Chunhui Plan"(Z2016177)
文摘The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the GGA/PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Two possible reaction pathways were investigated in this study. The result indicates that the reaction Re→TS1→IM1→TSA2→IMA2→TSA3→IMA3→TSA4→IMA4→TSA5→P2 is the main pathway, the activation energy of which is the lowest. Re→TS1→IM1 is the rate-limiting step, with the activation energy being 221.54 kJ·mol;and the reaction heat being 10.06 kJ·mol;. The dominant product predicted theoretically is in agreement with the experiment results.
基金Supported by the National Natural Science Foundation of China(No.20672104)
文摘The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G(d, p) level. Vibration analysis was carried out to confirm its identity as transitions' structure, and the intrinsic reaction coordinate method(IRC) was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other.
基金Project supported by the National Key Basic Research and Development Program (No. 2002CB410804) the National Natural Science Foundation of China (No. 30671255).
文摘Salicylic acid (SA) was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2+ (0, 0.05, 0.15, 0.25 mmol/L) for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA (treated with 0.1 mmol/L SA for 48 h before Pb stress) partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase (SOD), repressing the activity of catalase (CAT) and ascorbate peroxidase (APX) depending on the concentrations of Pb^2+ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity.