Charge accumulation and charge injection have been studied via the pulsed electroacoustic method on model cables prepared with different insulation and semicon materials,during application of high voltage direct curre...Charge accumulation and charge injection have been studied via the pulsed electroacoustic method on model cables prepared with different insulation and semicon materials,during application of high voltage direct current stress of up to electric field strength with 60 kV/mm and various temperatures or thermal gradient conditions.Insulation material technology concepts include crosslinked polyethylene with carbon black or crosslinked polyethylene with a coagent,and the comparative analysis under a variety of conditions provides insight into the benefits and potential limitations of each technology.Semiconductive shields utilized in the study include various carbon black loadings in polar copolymers with ethylene or blends of polar and non-polar polymers.Results with various semiconductive shields indicate that the properties of the semicon dominate the charge injection process regardless of insulation type.A comparison is made with other published work on charge injection and a discussion of charge injection as it relates to electrical stress and temperature is provided.展开更多
In this study,the interaction between primary amine and diketones was investigated.Three diketones with a general structure of—(CH2C(O)CH2C(O))-X-R(X is C,O or N and R is H and/or alkyl groups)were selected to react ...In this study,the interaction between primary amine and diketones was investigated.Three diketones with a general structure of—(CH2C(O)CH2C(O))-X-R(X is C,O or N and R is H and/or alkyl groups)were selected to react with primary amine in aqueous solutions.The reaction was in-situ monitored by Raman technique and the reaction products were identified by FTIR,NMR and LC-MS.It is found that the reaction products strongly depend on the structures of diketones.When X is nitrogen,the expected Schiff base or its analog can be obtained.However,Schiff base or its analog is not detected if X is C or O,instead,ion pairs or hydrolysis products are formed accordingly,suggesting critical impacts of acidity of CH2 inβ-diketone on the product formation.This study also shows that in-situ Raman is a powerful technique for reaction monitoring and structure characterization,which is useful for mechanism understanding.展开更多
Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose o...Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives.The research is approached from three focus areas that supplement and guide each other:characterization tests,sand-pack floods,and computational simulation.A number of key mechanisms for enhancing oil recovery were identified,high-temperature additive characterization tests were developed,and promising alkalis were tested in porous media.Simulation was employed to history-match sandpack flood production data,in order to demonstrate the effect of an additive on the oil–water relative permeability.Based on these results,it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil–water interfacial tension(IFT)by increasing the pH of the system.These organic bases favorably modify the interfacial energies between the immiscible oil–water phases and enable them to flow easily through the porous media during production.Sand-pack flood tests have successfully demonstrated a 10%–15%improvement in bitumen recovery,over baseline,in the presence of IFT-reducing additives.Simulation results further showed that an IFT reduction had a positive impact on SAGD performance.This work demonstrates the potential of organic bases to improve not only SAGD,but other steam injection processes.Furthermore,a number of experimental methods were developed,tried,and tested during the course of this work.展开更多
Isolated case reports have circumstantially linked the use of the herbicide 2.4-dichlorophen-oxyacetic acid (2,4-D) to polyneuropathy. However, a critical review of the literature reveals numerous reasons for doubting...Isolated case reports have circumstantially linked the use of the herbicide 2.4-dichlorophen-oxyacetic acid (2,4-D) to polyneuropathy. However, a critical review of the literature reveals numerous reasons for doubting a relationship of 2.4-D to polyneuropathy: (1) too few cases given the wide use of the chemical: (2) no valid toxicologic or epidemiologic evidence; (3) the diversity of antecedent illness; (4) an unlikely time sequence of antecedent illness to exposure (pharmacokinetics); (5) the lack of polyneuropathy in medical patients given repetitive doses of 2.4-D; (6) the lack of polyneuropathy in heavily exposed military personnel involved in operation Ranch Hand; (7) the biological properties of 2.4-D which minimize penetration of 2.4-D into the nervous system under normal exposure conditions; and (8) the lack of polyneuropathy in a variety of experimental animal species given 2,4-D by several routes of exposure and at dose levels and durations of exposure many times greater than human applicator exposure. Thus, the weight of evidence indicates that 2.4-D is an unlikely cause of polyneuropathy. 1990 Academic Press. Inc.展开更多
A facile approach has been adopted for coating cross-linked polystyrene(PS) shells on the surface of Fe304 magnetic clusters using reflux-precipitation polymerization(RPP).Treating the PS shell with chlorosulfonic aci...A facile approach has been adopted for coating cross-linked polystyrene(PS) shells on the surface of Fe304 magnetic clusters using reflux-precipitation polymerization(RPP).Treating the PS shell with chlorosulfonic acid yields magnetic composite particles with acid functionality.By adjusting the amount and proportion of monomers(styrene and divinylbenzene),the obtained magnetic composite particle solid acid(MPM-5 S) exhibits a saturation magnetization value of 18 emu/g,a specific surface area of 243 m^2/g and an acid density of 2.113 mmol/g.The MPM-5 S magnetic solid acid catalyst was evaluated for esterification of oleic acid with methanol to prepare biodiesel.Under mild conditions,the conversion of oleic acid reached 91%,which was much higher than the catalytic activity of Amberlyst-15 and close to the catalytic activity of concentrated H2 SO4.The solid acid catalyst can be recovered by magnetic separation and reused three times maintaining over 95% of its initial catalytic activity.Additionally,the solid acid can be used to catalyze the dehydration of fructose to 5-hydroxymethylfurfural.展开更多
There is no doubt about the potential technological significance of nanofluids. The promising application areas have been identified as effective heat transfer fluids, contrast agents in magnetic resonance imaging, ma...There is no doubt about the potential technological significance of nanofluids. The promising application areas have been identified as effective heat transfer fluids, contrast agents in magnetic resonance imaging, magnetohyperthermia treatment, precursors to high performance nanocomposites and ordered nanostructures. However, commercial applications are rare, in part due to the limited understanding of the nanofluid fundamentals such as colloid stability, phase diagrams and rheology. This paper intends to provide a brief overview of the scientific disciplines that are important to nanofluids, and the interconnection among different disciplines in order to gain a perspective on the future development of this intriguing area.展开更多
The fluidized-bed polymerization process has been in use for decades. From the manufacturer＇s perspective it is desirable to improve technology without major modification of the reactor system. Therefore, in order to...The fluidized-bed polymerization process has been in use for decades. From the manufacturer＇s perspective it is desirable to improve technology without major modification of the reactor system. Therefore, in order to meet the demand for new products or more efficient reactor operation, manufacturers prefer to improve the catalyst system in the most cost effective manner. Using polypropylene production as an example, some recent advances in fluidized-bed polymerization technology are presented.展开更多
文摘Charge accumulation and charge injection have been studied via the pulsed electroacoustic method on model cables prepared with different insulation and semicon materials,during application of high voltage direct current stress of up to electric field strength with 60 kV/mm and various temperatures or thermal gradient conditions.Insulation material technology concepts include crosslinked polyethylene with carbon black or crosslinked polyethylene with a coagent,and the comparative analysis under a variety of conditions provides insight into the benefits and potential limitations of each technology.Semiconductive shields utilized in the study include various carbon black loadings in polar copolymers with ethylene or blends of polar and non-polar polymers.Results with various semiconductive shields indicate that the properties of the semicon dominate the charge injection process regardless of insulation type.A comparison is made with other published work on charge injection and a discussion of charge injection as it relates to electrical stress and temperature is provided.
文摘In this study,the interaction between primary amine and diketones was investigated.Three diketones with a general structure of—(CH2C(O)CH2C(O))-X-R(X is C,O or N and R is H and/or alkyl groups)were selected to react with primary amine in aqueous solutions.The reaction was in-situ monitored by Raman technique and the reaction products were identified by FTIR,NMR and LC-MS.It is found that the reaction products strongly depend on the structures of diketones.When X is nitrogen,the expected Schiff base or its analog can be obtained.However,Schiff base or its analog is not detected if X is C or O,instead,ion pairs or hydrolysis products are formed accordingly,suggesting critical impacts of acidity of CH2 inβ-diketone on the product formation.This study also shows that in-situ Raman is a powerful technique for reaction monitoring and structure characterization,which is useful for mechanism understanding.
基金support of this research from The Dow Chemical Company
文摘Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives.The research is approached from three focus areas that supplement and guide each other:characterization tests,sand-pack floods,and computational simulation.A number of key mechanisms for enhancing oil recovery were identified,high-temperature additive characterization tests were developed,and promising alkalis were tested in porous media.Simulation was employed to history-match sandpack flood production data,in order to demonstrate the effect of an additive on the oil–water relative permeability.Based on these results,it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil–water interfacial tension(IFT)by increasing the pH of the system.These organic bases favorably modify the interfacial energies between the immiscible oil–water phases and enable them to flow easily through the porous media during production.Sand-pack flood tests have successfully demonstrated a 10%–15%improvement in bitumen recovery,over baseline,in the presence of IFT-reducing additives.Simulation results further showed that an IFT reduction had a positive impact on SAGD performance.This work demonstrates the potential of organic bases to improve not only SAGD,but other steam injection processes.Furthermore,a number of experimental methods were developed,tried,and tested during the course of this work.
文摘Isolated case reports have circumstantially linked the use of the herbicide 2.4-dichlorophen-oxyacetic acid (2,4-D) to polyneuropathy. However, a critical review of the literature reveals numerous reasons for doubting a relationship of 2.4-D to polyneuropathy: (1) too few cases given the wide use of the chemical: (2) no valid toxicologic or epidemiologic evidence; (3) the diversity of antecedent illness; (4) an unlikely time sequence of antecedent illness to exposure (pharmacokinetics); (5) the lack of polyneuropathy in medical patients given repetitive doses of 2.4-D; (6) the lack of polyneuropathy in heavily exposed military personnel involved in operation Ranch Hand; (7) the biological properties of 2.4-D which minimize penetration of 2.4-D into the nervous system under normal exposure conditions; and (8) the lack of polyneuropathy in a variety of experimental animal species given 2,4-D by several routes of exposure and at dose levels and durations of exposure many times greater than human applicator exposure. Thus, the weight of evidence indicates that 2.4-D is an unlikely cause of polyneuropathy. 1990 Academic Press. Inc.
基金financially supported by the National Natural Science Foundation of China(No.21802039)Hunan Provincial Natural Science Foundation of China(No.2019JJ40061)+3 种基金Scientific Research Fund of Hunan Provincial Education Department (No.18A422)the National College Students’ Innovation and Entrepreneurship Training Program Project,Hunan Province College Students’ Research Learning and Innovative Experiment Projectthe Acteristic Application Discipline of Material Science Engineering in Hunan Province(Hunan Provincial Education Department Notice(No.[2018]469)funding from Dow through the University Partnership Initiative
文摘A facile approach has been adopted for coating cross-linked polystyrene(PS) shells on the surface of Fe304 magnetic clusters using reflux-precipitation polymerization(RPP).Treating the PS shell with chlorosulfonic acid yields magnetic composite particles with acid functionality.By adjusting the amount and proportion of monomers(styrene and divinylbenzene),the obtained magnetic composite particle solid acid(MPM-5 S) exhibits a saturation magnetization value of 18 emu/g,a specific surface area of 243 m^2/g and an acid density of 2.113 mmol/g.The MPM-5 S magnetic solid acid catalyst was evaluated for esterification of oleic acid with methanol to prepare biodiesel.Under mild conditions,the conversion of oleic acid reached 91%,which was much higher than the catalytic activity of Amberlyst-15 and close to the catalytic activity of concentrated H2 SO4.The solid acid catalyst can be recovered by magnetic separation and reused three times maintaining over 95% of its initial catalytic activity.Additionally,the solid acid can be used to catalyze the dehydration of fructose to 5-hydroxymethylfurfural.
基金The Dow Chemical Companyfor its support of the writing of this manuscript
文摘There is no doubt about the potential technological significance of nanofluids. The promising application areas have been identified as effective heat transfer fluids, contrast agents in magnetic resonance imaging, magnetohyperthermia treatment, precursors to high performance nanocomposites and ordered nanostructures. However, commercial applications are rare, in part due to the limited understanding of the nanofluid fundamentals such as colloid stability, phase diagrams and rheology. This paper intends to provide a brief overview of the scientific disciplines that are important to nanofluids, and the interconnection among different disciplines in order to gain a perspective on the future development of this intriguing area.
文摘The fluidized-bed polymerization process has been in use for decades. From the manufacturer＇s perspective it is desirable to improve technology without major modification of the reactor system. Therefore, in order to meet the demand for new products or more efficient reactor operation, manufacturers prefer to improve the catalyst system in the most cost effective manner. Using polypropylene production as an example, some recent advances in fluidized-bed polymerization technology are presented.
