采用液相色谱-三重四极杆串联质谱(liquid chromatography-triple quadrupole tandem mass spectrometry,LC-MS/MS)法,测定尼龙/聚丙烯(polyamide/castpolypropylene,PA/CPP)蒸煮袋中2种初级芳香胺(primary aromatic amines,PAAs)物质2...采用液相色谱-三重四极杆串联质谱(liquid chromatography-triple quadrupole tandem mass spectrometry,LC-MS/MS)法,测定尼龙/聚丙烯(polyamide/castpolypropylene,PA/CPP)蒸煮袋中2种初级芳香胺(primary aromatic amines,PAAs)物质2,4-二氨基甲苯(2,4-diaminotoluene,2,4-TDA)和4,4’-二氨基二苯甲烷(4,4’-diaminodiphenylmethane,4,4’-MDA)向4%乙酸食品模拟液的迁移量,并研究不同热处理及杀菌方式(巴氏杀菌、蒸、煮、高温灭菌、紫外杀菌)对蒸煮袋中这2种物质向4%乙酸食品模拟物中迁移的影响。实验结果表明:LC-MS/MS检测2,4-TDA和4,4’-MDA迁移量的检出限均不大于0.02μg/kg,定量限均不大于0.05μg/kg,满足欧盟标准中对于PAAs限量的检测要求。在此基础上,研究发现除紫外杀菌对2,4-TDA和4,4’-MDA的迁移无显著影响外,巴氏杀菌、蒸、煮、高温灭菌均会促进PA/CPP蒸煮袋中2,4-TDA和4,4’-MDA向4%乙酸溶液的迁移,迁移量随着迁移温度的升高显著增加(P<0.05)。根据迁移结果可知,在对蒸煮袋包装的食品进行杀菌处理时,紫外和巴氏杀菌是相对安全的处理方式;另外,在对蒸煮袋包装的食品进行加热时,相比煮,蒸是更为安全的一种加热方式。而在121℃高温灭菌15 min条件下,2种PA/CPP样品袋中4,4’-MDA的迁移量分别达到2.733μg/kg和3.113μg/kg,均高于欧盟正在修订的对单个PAAs的迁移限量(0.002 mg/kg),具有潜在的食品安全风险。可见,当利用PA/CPP蒸煮袋包装食品时,不同热处理方式对胶黏剂中PAAs的迁移量及食品安全的影响值得重点关注。展开更多
Chitosan derived from crab shells, was used to prepare the graft polymer in aqueous solution with acrylamide （AM） and methacrylatoethyl trimethyl ammonium chloride （DMC） as raw materials and ceric ammonium nitrate...Chitosan derived from crab shells, was used to prepare the graft polymer in aqueous solution with acrylamide （AM） and methacrylatoethyl trimethyl ammonium chloride （DMC） as raw materials and ceric ammonium nitrate （CAN） as initiator. The flocculation ability of the resulting polymer （PCAD） was studied in waste water treatment experiments. Its properties were determined on the basis of the transmittance of waste water after flocculation. The effects of ehitosan and DMC content on PCAD＇s flocculation ability were studied. Floeculation experiments were also undertaken under various pH conditions. According to the experimental data, the flocculation ability could be improved when chitosan content decreased in the raw material, but the monomer conversion would decrease obviously. When the ehitosan＇s content was more than 65%, AM and DMC groups were less on each chitosan molecule. So PCAD＇s flocculation ability was poor. Similarly, high content of DMC would result in low monomer conversion and high flocculation ability. PCAD molecules with more DMC group had more positive charges. It was favorable to flocculation. However, monomer conversion would decrease with the increase of DMC content. The suitable conditions were that chitosan and DMC contents were 65% and 15-20%, respectively. The experiment data showed that PCAD had good flocculation ability under weak acidic condition. Its ability would be weakened by strong acidic or alkaline condition. The flocculation efficiency was the best at pH of 5.5 when PCAD＇s dosage was 8mg-Lk Compared with cationic polymer （the copolymer of AM and DMC, PAD）, PCAD showed better flocculation ability under acid and neutral conditions, but worse ability under alkaline condition.展开更多
Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared...Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl （acryloxyethyl） ammonium bromide （DMB） and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants with the （012） surface of alumina crystal （A1203） have been simulated by molecular dynamics method. All the polymers can bind tightly with A1203 crystal, the interaction between the O of polymers and A1 of the （012） surface of A1203 is significantly strong. The order of binding energy is as follows： P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, implying a better flocculation performance of P（DMB-co-AM） than the others. Analy- sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the A1 atoms of A1203. The poly- mers＇ structures deform when they combine with A1203 crystal, but the deformation en- ergies are low and far less than non-bonding energies. Flocculation experiments in sus- pension medium of l%Kaolin show a transmittancy of 90.8% for 6 mg/L P（DMB-co-AM） and 73.0% for P（AM）. The sequence of flocculation performance of four polymers is P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, which is in excellent agreement with the simulation results of binding energy.展开更多
In the present study, the aptitudes of acrylamide grafted cellulose to remove Cu（Ⅱ） ions from aqueous solutions were investigated. The preparation process was carried out through graft copolymerization of acrylamid...In the present study, the aptitudes of acrylamide grafted cellulose to remove Cu（Ⅱ） ions from aqueous solutions were investigated. The preparation process was carried out through graft copolymerization of acrylamide onto cellulose, using ceric ammonium nitrate as an initiator. Fourier transform Infrared spectroscopy was used to confirm and characterization poly acrylamide-grafted cellulose formation. Batch experiments of Cu（Ⅱ） ions adsorption on the grafted cellulose adsorbent were performed. Effects of initial pH of the solution, contact time and initial Cu（Ⅱ） concentration on the adsorption of Cu（Ⅱ） were studied. The maximum adsorption of Cu（Ⅱ） ion on grafted cellulose is observed 90 mg/g at the initial pH of 6. Equilibrium time was reached within 3h. Kinetic data were analyzed using the pseudo-first-order, pseudo-second-order equations. The data fitted very well to the pseudo-second-order rate expression. The equilibrium data for adsorption isotherms of these metal ions on grafted cellulose were obtained using the Langmuir and Freundlich models and the Langmuir model was obtained to be in better correlation with the experimental data. The results showed that acrylamide-g-cellulose developed in this study could be an economical and effective adsorbent for application in removal of copper ion from water and waste waters.展开更多
The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer so- lution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sand...The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer so- lution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandstone reservoirs in EOR projects. To alleviate the matching problems between the layer permeability and the injected polymer molecular weight, a molecular weight adjusting device with porous medium was designed on the basis of mechanical degradation principle. In terms of four variables （polymer concentration, pore diameter, length of shear component and flow rate ）, the theological behavior of hydrolyzed polyacrylamide （HPAM） solu- tion flowing through the device was investigated in detail. The change of these variables is able to control the shear rate of HPAM solutions through ceramic foam, and achieve the desired degree of shear degradation and the final theological parameters-viscosity loss, viscoelasticity and pressure drop. Therefore, a linear relationship between viscosity loss and shearing rate was established so as to obtain the targeted viscosity easily. Field tests in the Daqing Oil Field showed that the polymer molecular weight could drop 20% to 50%. In a word, the results could guide the industrial application of the novel device and the further study of polymer degradation flowing through the porous medium.展开更多
AIM:To investigate the association between hepatocel-lular carcinoma (HCC) susceptibility and a 12-bp inser-tion/deletion polymorphism (rs6147150) in the 3'UTR of ErbB4.METHODS:Using a case-control design,the rs61...AIM:To investigate the association between hepatocel-lular carcinoma (HCC) susceptibility and a 12-bp inser-tion/deletion polymorphism (rs6147150) in the 3'UTR of ErbB4.METHODS:Using a case-control design,the rs6147150 genotypes in 270 patients with HCC and 270 healthy controls were determined by direct polymerase chain reaction and polyacrylamide gel electrophoresis.Logistic regression was used to analyze the association between the polymorphism and cancer risk.RESULTS:Computational modeling suggested that rs6147150 was located in the seed region of hsa-let-7c,a potential target sequence in ErbB4 3'UTR.Logistic re-gression analysis showed that,compared with individu-als homozygous for wild-type,heterozygotes [adjusted odds ratio (OR)=1.48,95% confidence interval (CI)= 1.03-2.17,P=0.034] and individuals homozygous for 12-bp del/del (OR=2.50,95% CI=1.37-4.56,P=0.001) were at significantly higher risk of HCC.Car-riers of the "del" allele of rs6147150 had a 1.59-fold increased risk for HCC (95% CI=1.22-2.07,P=0.003).CONCLUSION:rs6147150 may be associated with HCC risk,in part through let-7c-mediated regulation,and may be involved in the pathogenesis of HCC in Chi-nese populations.展开更多
Polyacrylamide （PAM） film was electrosynthesized on mild steel by cyclic voltammetry using Ce （IV） salt-oxalic acid as supporting electrolyte. Polymerization was initiated by a free radical that was formed by the ...Polyacrylamide （PAM） film was electrosynthesized on mild steel by cyclic voltammetry using Ce （IV） salt-oxalic acid as supporting electrolyte. Polymerization was initiated by a free radical that was formed by the fast reaction of oxalic acid and Ce （IV）. The electrolysis of the reaction solution resulted in regeneration of Ce （IV）, which could oxidize oxalic acid to produce radicals. The effect of temperature on the yield of electroinitiated polymerization was performed. The potential sweep rates were changed to achieve the polymer film with different thickness. Protective properties of the PAM film for corrosion of mild steel in 1 M NaCI aqueous solution were investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy （EIS）. The structure of PAM film on mild steel was investigated by using physicochemical methods such as elemental analysis of C, H, N, physical chemical methods and FTIR spectrometer. The influence of scan repetition and scan rate on the formation of polymer film was studied at a current density of 1 mA/cm2. The results of these studies reveal that the corrosion resistance of the PAM-coated mild steel was significantly higher and the corrosion rate was considerably lower than that of uncoated steel. The PAM film was formed with lower sweep rate leading to more positive shift of corrosion potential and greater charge transfer resistance, reflecting higher inhibition for corrosion of the mild steel.展开更多
Drilling fluid additives has a major impact on rheology behavior and other performances of the drilling fluid.The key to low temperature drilling fluids is choosing antifreeze and polymer agent which have a strong abi...Drilling fluid additives has a major impact on rheology behavior and other performances of the drilling fluid.The key to low temperature drilling fluids is choosing antifreeze and polymer agent which have a strong ability in resisting low temperature.On the basis of determining glycol as antifreeze agent,the low-temperature-performance and capacities of anti-collapse of regular validity mud agents have been studied,the mechanism of anti-caving of the partially hydrolyzed polyacrylamide(PHPA),polypropylene potassium(KPA) and PAC-141 polymer additives have been also analyzed.A pilot study of compatibility between ethylene glycol and the polymers has educed that the polymers,ethylene glycol and inorganic salt are compatible,and they can significantly reduce the freezing point of drilling fluid.Anti-collapse ability of the drilling mud is the results of synergistic action among the agents.展开更多
Protein-polymer hybrids consisting of protein and natural polymers or synthetic polymers exhibit superior properties to un- modified proteins, generating a high demand for these materials in the fields of medicine, bi...Protein-polymer hybrids consisting of protein and natural polymers or synthetic polymers exhibit superior properties to un- modified proteins, generating a high demand for these materials in the fields of medicine, biotechnology, and nanotechnology. Herein, protein-polysaccharide hybrids were fabricated via the formation of an amide bond between bovine serum albumin （BSA） and chitosan （CS） using N-ethyl-N-（3-dimethylaminopropyl） carbodiimide hydrochloride （EDC） as the couple reagent. FTIR spectrum reveals that the carboxyl group of BSA conjugated with the amino group of chitosan backbone. The molecular weight of BSA-CS hybrids was identified by matrix-associated laser desorption ionization time of flight mass spectra （MALDI-TOF MS） and sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. The maximum number of chitosan chains binding to each BSA molecule was estimated as 6, and the optimal number was estimated as 2. In addition, the secondary structure and surface property of BSA were dependent upon the number of polymer conjugating on protein. The secondary structure of BSA was not significantly changed, if a few chitosans were coupled with BSA. By further increasing the molar ratio of chitosan to BSA, the secondary structure of BSA was markedly damaged. The surface＇s negative charges of modified BSA also decreased. The result of native polyaerylamide gel electrophoresis （native-PAGE） also demonstrated the changes in surface charges and molecular weight of BSA-CS hybrids.展开更多
Thermo-responsive polyrotaxane （PR）-based triblock copolymers were synthesized via the atom transfer radical polymeriza- tion （ATRP） of N-isopropylacrylamide initiated with self-assemblies made from a distal 2-bro...Thermo-responsive polyrotaxane （PR）-based triblock copolymers were synthesized via the atom transfer radical polymeriza- tion （ATRP） of N-isopropylacrylamide initiated with self-assemblies made from a distal 2-bromoisobutyryl end-capped Plu- ronic 17R4 （PPOI4-PEG24-PPOI4） with a varying amount of β-cyclodextrins （β-CDs） in the presence of Cu（I）C1/PMDETA at 25 ~C in aqueous solution. The molecular structure was characterized by means of ~H NMR, FTIR, WXRD, GPC, TGA and DSC analyses. About half of [3-CDs are still entrapped on the Pluronic 17R4 chain while the number of incorporated NIPAAm monomers is nearly a double feed value in the resulting copolymers. The aggregate morphologies in aqueous solution were evidenced by TEM observations. A two-step thermo-responsive transition arising from a combination of a polypseudorotaxane middle block with poly（N-isopropylacrylamide） flanking blocks was also demonstrated by turbidity measurements. Given their thermo-responsive behavior in aqueous solution, these PR-based triblock copolymers show the potential to be used as smart materials for the controlled drug delivery systems, biosensors, and the like.展开更多
文摘采用液相色谱-三重四极杆串联质谱(liquid chromatography-triple quadrupole tandem mass spectrometry,LC-MS/MS)法,测定尼龙/聚丙烯(polyamide/castpolypropylene,PA/CPP)蒸煮袋中2种初级芳香胺(primary aromatic amines,PAAs)物质2,4-二氨基甲苯(2,4-diaminotoluene,2,4-TDA)和4,4’-二氨基二苯甲烷(4,4’-diaminodiphenylmethane,4,4’-MDA)向4%乙酸食品模拟液的迁移量,并研究不同热处理及杀菌方式(巴氏杀菌、蒸、煮、高温灭菌、紫外杀菌)对蒸煮袋中这2种物质向4%乙酸食品模拟物中迁移的影响。实验结果表明:LC-MS/MS检测2,4-TDA和4,4’-MDA迁移量的检出限均不大于0.02μg/kg,定量限均不大于0.05μg/kg,满足欧盟标准中对于PAAs限量的检测要求。在此基础上,研究发现除紫外杀菌对2,4-TDA和4,4’-MDA的迁移无显著影响外,巴氏杀菌、蒸、煮、高温灭菌均会促进PA/CPP蒸煮袋中2,4-TDA和4,4’-MDA向4%乙酸溶液的迁移,迁移量随着迁移温度的升高显著增加(P<0.05)。根据迁移结果可知,在对蒸煮袋包装的食品进行杀菌处理时,紫外和巴氏杀菌是相对安全的处理方式;另外,在对蒸煮袋包装的食品进行加热时,相比煮,蒸是更为安全的一种加热方式。而在121℃高温灭菌15 min条件下,2种PA/CPP样品袋中4,4’-MDA的迁移量分别达到2.733μg/kg和3.113μg/kg,均高于欧盟正在修订的对单个PAAs的迁移限量(0.002 mg/kg),具有潜在的食品安全风险。可见,当利用PA/CPP蒸煮袋包装食品时,不同热处理方式对胶黏剂中PAAs的迁移量及食品安全的影响值得重点关注。
基金supported by Young Scientist Foundation (2008BS09001) from the Department of Science and Technology of Shandong Province
文摘Chitosan derived from crab shells, was used to prepare the graft polymer in aqueous solution with acrylamide （AM） and methacrylatoethyl trimethyl ammonium chloride （DMC） as raw materials and ceric ammonium nitrate （CAN） as initiator. The flocculation ability of the resulting polymer （PCAD） was studied in waste water treatment experiments. Its properties were determined on the basis of the transmittance of waste water after flocculation. The effects of ehitosan and DMC content on PCAD＇s flocculation ability were studied. Floeculation experiments were also undertaken under various pH conditions. According to the experimental data, the flocculation ability could be improved when chitosan content decreased in the raw material, but the monomer conversion would decrease obviously. When the ehitosan＇s content was more than 65%, AM and DMC groups were less on each chitosan molecule. So PCAD＇s flocculation ability was poor. Similarly, high content of DMC would result in low monomer conversion and high flocculation ability. PCAD molecules with more DMC group had more positive charges. It was favorable to flocculation. However, monomer conversion would decrease with the increase of DMC content. The suitable conditions were that chitosan and DMC contents were 65% and 15-20%, respectively. The experiment data showed that PCAD had good flocculation ability under weak acidic condition. Its ability would be weakened by strong acidic or alkaline condition. The flocculation efficiency was the best at pH of 5.5 when PCAD＇s dosage was 8mg-Lk Compared with cationic polymer （the copolymer of AM and DMC, PAD）, PCAD showed better flocculation ability under acid and neutral conditions, but worse ability under alkaline condition.
文摘Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl （acryloxyethyl） ammonium bromide （DMB） and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants with the （012） surface of alumina crystal （A1203） have been simulated by molecular dynamics method. All the polymers can bind tightly with A1203 crystal, the interaction between the O of polymers and A1 of the （012） surface of A1203 is significantly strong. The order of binding energy is as follows： P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, implying a better flocculation performance of P（DMB-co-AM） than the others. Analy- sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the A1 atoms of A1203. The poly- mers＇ structures deform when they combine with A1203 crystal, but the deformation en- ergies are low and far less than non-bonding energies. Flocculation experiments in sus- pension medium of l%Kaolin show a transmittancy of 90.8% for 6 mg/L P（DMB-co-AM） and 73.0% for P（AM）. The sequence of flocculation performance of four polymers is P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, which is in excellent agreement with the simulation results of binding energy.
文摘In the present study, the aptitudes of acrylamide grafted cellulose to remove Cu（Ⅱ） ions from aqueous solutions were investigated. The preparation process was carried out through graft copolymerization of acrylamide onto cellulose, using ceric ammonium nitrate as an initiator. Fourier transform Infrared spectroscopy was used to confirm and characterization poly acrylamide-grafted cellulose formation. Batch experiments of Cu（Ⅱ） ions adsorption on the grafted cellulose adsorbent were performed. Effects of initial pH of the solution, contact time and initial Cu（Ⅱ） concentration on the adsorption of Cu（Ⅱ） were studied. The maximum adsorption of Cu（Ⅱ） ion on grafted cellulose is observed 90 mg/g at the initial pH of 6. Equilibrium time was reached within 3h. Kinetic data were analyzed using the pseudo-first-order, pseudo-second-order equations. The data fitted very well to the pseudo-second-order rate expression. The equilibrium data for adsorption isotherms of these metal ions on grafted cellulose were obtained using the Langmuir and Freundlich models and the Langmuir model was obtained to be in better correlation with the experimental data. The results showed that acrylamide-g-cellulose developed in this study could be an economical and effective adsorbent for application in removal of copper ion from water and waste waters.
基金Supported by the Program for Yangtse River Scholars and Innovative Research Terms in Universities(IRT0936)the National Basic Research Program of China(2009CB219905+2 种基金2009CB219907)the Daqing Oilfield Co.Ltd
文摘The separate-layer injection in different interlayers and the injection of the same-molecular-weight polymer so- lution in a layer are necessary in the polymer flooding process because of heterogeneous multilayer sandstone reservoirs in EOR projects. To alleviate the matching problems between the layer permeability and the injected polymer molecular weight, a molecular weight adjusting device with porous medium was designed on the basis of mechanical degradation principle. In terms of four variables （polymer concentration, pore diameter, length of shear component and flow rate ）, the theological behavior of hydrolyzed polyacrylamide （HPAM） solu- tion flowing through the device was investigated in detail. The change of these variables is able to control the shear rate of HPAM solutions through ceramic foam, and achieve the desired degree of shear degradation and the final theological parameters-viscosity loss, viscoelasticity and pressure drop. Therefore, a linear relationship between viscosity loss and shearing rate was established so as to obtain the targeted viscosity easily. Field tests in the Daqing Oil Field showed that the polymer molecular weight could drop 20% to 50%. In a word, the results could guide the industrial application of the novel device and the further study of polymer degradation flowing through the porous medium.
基金Supported by The Applied Basic Research Programs of Science and Technology Commission Foundation of Suzhou,No.sys201047
文摘AIM:To investigate the association between hepatocel-lular carcinoma (HCC) susceptibility and a 12-bp inser-tion/deletion polymorphism (rs6147150) in the 3'UTR of ErbB4.METHODS:Using a case-control design,the rs6147150 genotypes in 270 patients with HCC and 270 healthy controls were determined by direct polymerase chain reaction and polyacrylamide gel electrophoresis.Logistic regression was used to analyze the association between the polymorphism and cancer risk.RESULTS:Computational modeling suggested that rs6147150 was located in the seed region of hsa-let-7c,a potential target sequence in ErbB4 3'UTR.Logistic re-gression analysis showed that,compared with individu-als homozygous for wild-type,heterozygotes [adjusted odds ratio (OR)=1.48,95% confidence interval (CI)= 1.03-2.17,P=0.034] and individuals homozygous for 12-bp del/del (OR=2.50,95% CI=1.37-4.56,P=0.001) were at significantly higher risk of HCC.Car-riers of the "del" allele of rs6147150 had a 1.59-fold increased risk for HCC (95% CI=1.22-2.07,P=0.003).CONCLUSION:rs6147150 may be associated with HCC risk,in part through let-7c-mediated regulation,and may be involved in the pathogenesis of HCC in Chi-nese populations.
文摘Polyacrylamide （PAM） film was electrosynthesized on mild steel by cyclic voltammetry using Ce （IV） salt-oxalic acid as supporting electrolyte. Polymerization was initiated by a free radical that was formed by the fast reaction of oxalic acid and Ce （IV）. The electrolysis of the reaction solution resulted in regeneration of Ce （IV）, which could oxidize oxalic acid to produce radicals. The effect of temperature on the yield of electroinitiated polymerization was performed. The potential sweep rates were changed to achieve the polymer film with different thickness. Protective properties of the PAM film for corrosion of mild steel in 1 M NaCI aqueous solution were investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy （EIS）. The structure of PAM film on mild steel was investigated by using physicochemical methods such as elemental analysis of C, H, N, physical chemical methods and FTIR spectrometer. The influence of scan repetition and scan rate on the formation of polymer film was studied at a current density of 1 mA/cm2. The results of these studies reveal that the corrosion resistance of the PAM-coated mild steel was significantly higher and the corrosion rate was considerably lower than that of uncoated steel. The PAM film was formed with lower sweep rate leading to more positive shift of corrosion potential and greater charge transfer resistance, reflecting higher inhibition for corrosion of the mild steel.
文摘Drilling fluid additives has a major impact on rheology behavior and other performances of the drilling fluid.The key to low temperature drilling fluids is choosing antifreeze and polymer agent which have a strong ability in resisting low temperature.On the basis of determining glycol as antifreeze agent,the low-temperature-performance and capacities of anti-collapse of regular validity mud agents have been studied,the mechanism of anti-caving of the partially hydrolyzed polyacrylamide(PHPA),polypropylene potassium(KPA) and PAC-141 polymer additives have been also analyzed.A pilot study of compatibility between ethylene glycol and the polymers has educed that the polymers,ethylene glycol and inorganic salt are compatible,and they can significantly reduce the freezing point of drilling fluid.Anti-collapse ability of the drilling mud is the results of synergistic action among the agents.
基金supported by the National Natural Science Foundation of China (21164003,20964002)the Gansu Sci & Techn Support Project(1011GKCA017)+2 种基金the Fundamental Res. Funds Univ. Gansu Province(2010-176)Lanzhou Science Technology Bureau (2009-1-14)NWNU-kjcxgc-03-63
文摘Protein-polymer hybrids consisting of protein and natural polymers or synthetic polymers exhibit superior properties to un- modified proteins, generating a high demand for these materials in the fields of medicine, biotechnology, and nanotechnology. Herein, protein-polysaccharide hybrids were fabricated via the formation of an amide bond between bovine serum albumin （BSA） and chitosan （CS） using N-ethyl-N-（3-dimethylaminopropyl） carbodiimide hydrochloride （EDC） as the couple reagent. FTIR spectrum reveals that the carboxyl group of BSA conjugated with the amino group of chitosan backbone. The molecular weight of BSA-CS hybrids was identified by matrix-associated laser desorption ionization time of flight mass spectra （MALDI-TOF MS） and sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. The maximum number of chitosan chains binding to each BSA molecule was estimated as 6, and the optimal number was estimated as 2. In addition, the secondary structure and surface property of BSA were dependent upon the number of polymer conjugating on protein. The secondary structure of BSA was not significantly changed, if a few chitosans were coupled with BSA. By further increasing the molar ratio of chitosan to BSA, the secondary structure of BSA was markedly damaged. The surface＇s negative charges of modified BSA also decreased. The result of native polyaerylamide gel electrophoresis （native-PAGE） also demonstrated the changes in surface charges and molecular weight of BSA-CS hybrids.
基金supported by the National Natural Science Foundation of China (20974015)the Doctoral Program Foundation of Ministry of Education of China (20091101110029)
文摘Thermo-responsive polyrotaxane （PR）-based triblock copolymers were synthesized via the atom transfer radical polymeriza- tion （ATRP） of N-isopropylacrylamide initiated with self-assemblies made from a distal 2-bromoisobutyryl end-capped Plu- ronic 17R4 （PPOI4-PEG24-PPOI4） with a varying amount of β-cyclodextrins （β-CDs） in the presence of Cu（I）C1/PMDETA at 25 ~C in aqueous solution. The molecular structure was characterized by means of ~H NMR, FTIR, WXRD, GPC, TGA and DSC analyses. About half of [3-CDs are still entrapped on the Pluronic 17R4 chain while the number of incorporated NIPAAm monomers is nearly a double feed value in the resulting copolymers. The aggregate morphologies in aqueous solution were evidenced by TEM observations. A two-step thermo-responsive transition arising from a combination of a polypseudorotaxane middle block with poly（N-isopropylacrylamide） flanking blocks was also demonstrated by turbidity measurements. Given their thermo-responsive behavior in aqueous solution, these PR-based triblock copolymers show the potential to be used as smart materials for the controlled drug delivery systems, biosensors, and the like.
