Functional materials may change color by heat and electricity separately or simultaneously in smart windows.These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are ...Functional materials may change color by heat and electricity separately or simultaneously in smart windows.These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of life.Unfortunately,dual-responsive materials have not received ample research attention due to economic and technological challenges.As a consequence,the broader utilization of smart windows faces hindrances.To address this new generational multistimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(NIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(NIPAM)n-based smart material for better utility and activity.These constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(thermochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(electrochromic)states.Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance.Each unique chromic mode operates independently and modulates visible and near-infrared(NIR)light in a distinct manner.Hence,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.展开更多
Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concern...Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concerns impede its practical viability.This work provides a hydrogen-bonded organic framework(HOF)modification strategy to simultaneously improve the electrochemical performance,thermal stability and incombustibility of separator.Melamine cyanurate(MCA),as a low-cost and reliable flame-retardant HOF,was implemented in the separator modification layer,which can prevent the battery short circuit even at a high temperature.In addition,the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte.The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3%after 300 cycles at 1.0 C.Collectively,the usage of MCA in lithium-ion batteries(LIBs)affords a simple,low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.展开更多
1. Foreword Energy storage plays a key role in the transition towards a carbon-neutral economy. By balancing power grids and saving surplus energy, it represents a concrete means of improving energy efficiency and int...1. Foreword Energy storage plays a key role in the transition towards a carbon-neutral economy. By balancing power grids and saving surplus energy, it represents a concrete means of improving energy efficiency and integrating more renewable energy sources into electricity systems. A variety of technologies to store energy are developing at a fast pace and increasingly becomingmoremarketcompetitive,includingtraditional electric energy storage, thermal energy storage, and newly developed hydrogen energy storage, etc. The demand for energy storage system with high power and efficiency boosts the development in the advanced techniques and materials,such as batteries, super-capacitors, molten salts, and catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).展开更多
Up to this date,researchers are still facing difficulties to expand the technology of direct methanol fuel cells(DMFCs) because of the high overpotential required to oxidize the methanol and its relatively poor perfor...Up to this date,researchers are still facing difficulties to expand the technology of direct methanol fuel cells(DMFCs) because of the high overpotential required to oxidize the methanol and its relatively poor performance due to CO poisoning of the leading-high cost anode catalyst.In line with this,we have successfully modified the morphological structure and composition of low cost cobalt based-metal oxides,MCo_2O_4(M = Zn and Ni),with the simple and noble use of polyvinyl pyrrolidone(PVP) as growth modifier and surface stabilizer during the synthesis of nanoparticles in our previous reports,which shown high electrocatalytic activity and strong stability.Due to the good performance of our PVP modified MCo_2O_4 towards pseudocapacitor and oxygen evolution reaction applications,we decided to extend our research study to methanol oxidation reaction.Remarkably,PVP modified Ni Co_2O_4 electrode directly grown on nickel foam substrate via a simple hydrothermal process exhibited better performance compared with PVP modified ZnCo_2O_4 and NiCo_2O_4 without PVP.It had obtained a remarkably low onset potential of 0.285 V and high current density of 280 m A cm^(-2),and shown great stability and high poison tolerance during a continuous CV cycling and Chronoamperometry test,which attained high efficiency of 86.86%and 98.52%,respectively.These positive results of PVP modified Ni Co_2O_4 electrode towards MOR might be attributed to its hierarchical 3 D nanostructures with highly mesoporous surface and large surface area which may have provided numerous electroactive sites,and the exceptional corrosion stability of Ni Co_2O_4 electrode in alkaline solution.展开更多
The present study involves the fabrication of tungsten trioxide(WO3) nanofibers by an electrospinning technique using polyvinyl pyrrolidone(PVP)/citric acid/tungstic acid as precursor solution. It was found that the P...The present study involves the fabrication of tungsten trioxide(WO3) nanofibers by an electrospinning technique using polyvinyl pyrrolidone(PVP)/citric acid/tungstic acid as precursor solution. It was found that the PVP concentration was one of the most crucial processing parameters determining the final properties of WO3 nanofibers. The optimum concentration of PVP was from 75 to 94 g L-1. The average diameter of the nanofibers increases with increasing the PVP concentration, whereas it is decreased after sintering and orthorhombic structure were formed at 500 °C. The photocatalytic properties of the as-synthesized nanofibers were also investigated by degrading methylene blue and twofold efficiency was obtained compared with that of commercial WO3 microparticles.展开更多
The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to prod...The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction(OER). In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction(XRD), X-ray photoelectron spectrum(XPS), field emission scanning electron microscopy(FE-SEM), high-resolution transmission electron microscopy(HR-TEM), and Brunauer–Emmett–Teller instrument(BET). Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.展开更多
Sand production along with the oil/gas detrimentally affects the oil production rate,downhole&subsurface facilities.Mechanical equipment and various chemicals like epoxy resin,furan resin,phenolic resin,etc.are us...Sand production along with the oil/gas detrimentally affects the oil production rate,downhole&subsurface facilities.Mechanical equipment and various chemicals like epoxy resin,furan resin,phenolic resin,etc.are used in the industry to reduce or eliminate this problem.In the present study,a blend of organic and inorganic silicates are used to consolidate loose sand in the presence and absence of crude oil using a core flooding apparatus.The effects of chemical concentration,pH,curing temperature and time,and the presence of residual oil on the consolidation treatment results such as compressive strength and permeability retention,were investigated and optimized.FT-IR and FE-SEM characterization techniques were employed to investigate the interaction between the chemical molecules and the sand grains.The current binding agent exhibited a viscosity of less than 6 cP at room temperature,which facilitates efficient pumping of binding agent into the desired formation through the well bore.The developed mixture demonstrated consolidation properties across all pH conditions.Furthermore,during the experimental investigation,the curing time and temperature was carefully optimized at 12 h and 423.15K,respectively to achieve the highest compressive strength of 2021 psi while achieving the permeability retention of 64%.The current chemical system exhibited improved consolidation capacity and can be effectively utilized for sand consolidation treatment in high-temperature formations.展开更多
A silica supported ionic liquid was synthesized and characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and thermogravimetric analy...A silica supported ionic liquid was synthesized and characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and thermogravimetric analysis. All these techniques, especially SEM results indicated the presence of well-defined spherical particles having diameters larger than the pristine silica particles, confirming the successful immobilization of the ionic liquid. The prepared silica supported ionic liquid was used in the reductive amination of cyclohexanone under different conditions with different azeotropic mixtures of formic acid and triethyl amine as a hydrogen source. The catalyst showed efficient catalytic performance and excellent yields of N-cyclohexyl amine derivatives in the range of 58% to 84% at 30 °C. After completion of the reaction, the catalyst was easily recovered by simple filtration and reused for another five cycles without any significant impact on product yields. The obtained catalytic performance indicates that the present catalyst is green, very active, and reusable for the reductive amination of cyclohexanone.展开更多
This study described a hydrometallurgical method to investigate the separation of rare earth elements(REEs)from rare earth polishing powder wastes(REPPWs)containing large amounts of rare earth oxides with a major ...This study described a hydrometallurgical method to investigate the separation of rare earth elements(REEs)from rare earth polishing powder wastes(REPPWs)containing large amounts of rare earth oxides with a major phase of CeO2 and minor phases of La2O3,Pr2O3,and Nd2O3 using a process devised by the authors.The suggested approach consisted of five processes:the synthesis of NaR E(SO4)2·xH2O from rare earth oxides in Na2SO4-H2SO4-H2 O solutions(Process 1),the conversion of NaR E(SO4)2·xH2O into RE(OH)3 using NaO H(Process 2),and the oxidation of Ce(OH)3 into Ce(OH)4 using air with O2 injection(Process 3),followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H2SO4,respectively.To confirm the high yield of NaR E(SO4)2·xH2O in Process 1,experiments were carried out under various Na2SO4 concentrations(0.4–2.5 mol/L),sulfuric acid concentrations(6–14 mol/L),and reaction temperatures(95–125 oC).In addition,the effect of the pH value on the separation of Ce(OH)4 in HCl-H2 O solutions with Ce(OH)4,La-,Pr-,and Nd(OH)3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.展开更多
A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, var...A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, variations in the texture and Lankford value of a 1070 aluminum sheet rolled by the cone-shaped roll were investigated. Rolling with the cone-shaped roll was found to impose intense shear strain at the edges of the specimen, specifically near the surface. The shear directions in the left and right portions of the specimen were opposite to each other. The surface and middle layer of the specimen rolled by the cone-shaped roll and the reference specimen were characterized by a shear texture and typical recrystallization texture components, respectively. Notably, the specimen rolled by the cone-shaped roll exhibited smaller texture intensity than the reference specimen, especially at the surface, and the shear texture-components were observed at relatively deeper positions. As a result of Lankford value measurements, the specimen rolled with the cone-shape roll exhibited a smaller planar anisotropy than the reference specimen and an average Lankford value close to unity, which are likely due to the texture modifications introduced during rolling with the cone-shaped roll.展开更多
The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen e...The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen electrolytic cell equipped with an electrostatic-induction potential-superposed water electrolytic cell that provides a stoichiometric H2-O2 fuel mixture during operation of the vehicle. This generator functions with zero power input, zero matter input and zero emission due to the so-called "zero power input" electrostatic-to-chemical energy conversion occurring in the electrolytic cell. Here, theoretical simulations were performed to verify the target performance of such generators, assuming a pair of FC (fuel cell) and electrolytic cell stacks, both of which are commercially available.展开更多
Opening up new and unlimited avenues in the biomedical field,tissue engineering and regenerative medicine,the electrospinning process is considered as a versatile and the most preferred technique for the fabrication o...Opening up new and unlimited avenues in the biomedical field,tissue engineering and regenerative medicine,the electrospinning process is considered as a versatile and the most preferred technique for the fabrication of nanofibers.These tailor-designed nanofibers provide a desirable and bio-inspired physiological niche to cells for better attachment and subsequent proliferation.In this review,an attempt is made to explain the importance of various topological and morphological parameters of nanofibrous scaffolds for efficient bio-mimicking.Some novel approaches(e.g.,appropriate functionalization and extracellular matrix derived from decellularization)utilized for better mimicking and exponential growth of regenerating tissues are also discussed.Furthermore,this review highlights the important parameters necessary for the attachment,proliferation and differentiation of the mesenchymal stem cells for tissue regeneration.The importance of growth factors and their role after introducing the electrospinning techniques for efficient delivery and their role in the proliferation of mesenchymal stem cells in the different specific lineage(e.g.,tenogenic,chondrogenic,neurogenic and osteogenic differentiation)are discussed.展开更多
The development of carbon dioxide(CO_2) sorbents that can operate at elevated temperatures is significant for the advancement of pre-combustion capture technologies.Recently, promoter-based systems composed of alkali/...The development of carbon dioxide(CO_2) sorbents that can operate at elevated temperatures is significant for the advancement of pre-combustion capture technologies.Recently, promoter-based systems composed of alkali/alkaline earth metal nitrates and/or carbonates have been considered as next-generation solid sorbents due to their improved CO_2 uptake and kinetics. However, obtaining stable MgO sorbents against temperature swing regeneration still remained challenging. Herein, we report MgO-TiO_2 solid sorbents promoted by eutectic mixture(KNO_3 and LiNO_3) for elevated temperature CO_2 sorption. The developed sorbents show improved CO_2 sorption capacity, which may be attributed to the alternative CO_2 sorption pathway provided by the ionization of highly dispersed MgO in the eutectic mixture. The MgO-TiO_2 framework was also shown to assist in retaining the MgO configuration by constraining its interaction with CO_2. Furthermore, it is demonstrated that constructing composite structures is essential to improve the CO_2 sorption characteristics,mainly recyclability, at elevated temperatures. The developed promoter integrated sorbents showed exceptionally high CO_2 sorption capacity of > 30 wt.% at an elevated temperature(300°C) with pronounced stability under temperature swing operation.展开更多
基金supported by the National Research Foundation (NRF)grants funded by the Ministry of Education (2020R1A6A1A03038817),Republic of Korea。
文摘Functional materials may change color by heat and electricity separately or simultaneously in smart windows.These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of life.Unfortunately,dual-responsive materials have not received ample research attention due to economic and technological challenges.As a consequence,the broader utilization of smart windows faces hindrances.To address this new generational multistimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(NIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(NIPAM)n-based smart material for better utility and activity.These constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(thermochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(electrochromic)states.Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance.Each unique chromic mode operates independently and modulates visible and near-infrared(NIR)light in a distinct manner.Hence,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.
基金supported by the National Key Research and Development Program of China(No.2022YFA1504100)the National Natural Science Foundation of China(Nos.22005215,22279089,and 22178251).
文摘Nickel-rich layered oxide cathode(LiNi_(x)Co_(y)Mn_(1−x−y)O_(2),x>0.5,NCM)shows substantial potential for applications in longer-range electrical vehicles.However,the rapid capacity decay and serious safety concerns impede its practical viability.This work provides a hydrogen-bonded organic framework(HOF)modification strategy to simultaneously improve the electrochemical performance,thermal stability and incombustibility of separator.Melamine cyanurate(MCA),as a low-cost and reliable flame-retardant HOF,was implemented in the separator modification layer,which can prevent the battery short circuit even at a high temperature.In addition,the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte.The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3%after 300 cycles at 1.0 C.Collectively,the usage of MCA in lithium-ion batteries(LIBs)affords a simple,low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.
文摘1. Foreword Energy storage plays a key role in the transition towards a carbon-neutral economy. By balancing power grids and saving surplus energy, it represents a concrete means of improving energy efficiency and integrating more renewable energy sources into electricity systems. A variety of technologies to store energy are developing at a fast pace and increasingly becomingmoremarketcompetitive,includingtraditional electric energy storage, thermal energy storage, and newly developed hydrogen energy storage, etc. The demand for energy storage system with high power and efficiency boosts the development in the advanced techniques and materials,such as batteries, super-capacitors, molten salts, and catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).
基金supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) - Grants funded by the Ministry of Trade,Industry and Energy (MOTIE) (No.20174010201160)the National Research Foundation of Korea (NRF) - Grant funded by the Ministry of Education (No.20090093816),Republic of Korea
文摘Up to this date,researchers are still facing difficulties to expand the technology of direct methanol fuel cells(DMFCs) because of the high overpotential required to oxidize the methanol and its relatively poor performance due to CO poisoning of the leading-high cost anode catalyst.In line with this,we have successfully modified the morphological structure and composition of low cost cobalt based-metal oxides,MCo_2O_4(M = Zn and Ni),with the simple and noble use of polyvinyl pyrrolidone(PVP) as growth modifier and surface stabilizer during the synthesis of nanoparticles in our previous reports,which shown high electrocatalytic activity and strong stability.Due to the good performance of our PVP modified MCo_2O_4 towards pseudocapacitor and oxygen evolution reaction applications,we decided to extend our research study to methanol oxidation reaction.Remarkably,PVP modified Ni Co_2O_4 electrode directly grown on nickel foam substrate via a simple hydrothermal process exhibited better performance compared with PVP modified ZnCo_2O_4 and NiCo_2O_4 without PVP.It had obtained a remarkably low onset potential of 0.285 V and high current density of 280 m A cm^(-2),and shown great stability and high poison tolerance during a continuous CV cycling and Chronoamperometry test,which attained high efficiency of 86.86%and 98.52%,respectively.These positive results of PVP modified Ni Co_2O_4 electrode towards MOR might be attributed to its hierarchical 3 D nanostructures with highly mesoporous surface and large surface area which may have provided numerous electroactive sites,and the exceptional corrosion stability of Ni Co_2O_4 electrode in alkaline solution.
基金supported by the National Research Foundation of Korea(NRF)-Grants funded by the Ministry of ScienceICT and Future Planning(2014R1A2A2A01004352)the Ministry of Education(2009-0093816),Republic of Korea
文摘The present study involves the fabrication of tungsten trioxide(WO3) nanofibers by an electrospinning technique using polyvinyl pyrrolidone(PVP)/citric acid/tungstic acid as precursor solution. It was found that the PVP concentration was one of the most crucial processing parameters determining the final properties of WO3 nanofibers. The optimum concentration of PVP was from 75 to 94 g L-1. The average diameter of the nanofibers increases with increasing the PVP concentration, whereas it is decreased after sintering and orthorhombic structure were formed at 500 °C. The photocatalytic properties of the as-synthesized nanofibers were also investigated by degrading methylene blue and twofold efficiency was obtained compared with that of commercial WO3 microparticles.
基金supported by the National Research Foundation of Korea(NRF)–Grants funded by the Ministry of Science,ICT and Future Planning(2014R1A2A2A01004352),Republic of Korea
文摘The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction(OER). In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction(XRD), X-ray photoelectron spectrum(XPS), field emission scanning electron microscopy(FE-SEM), high-resolution transmission electron microscopy(HR-TEM), and Brunauer–Emmett–Teller instrument(BET). Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.
文摘Sand production along with the oil/gas detrimentally affects the oil production rate,downhole&subsurface facilities.Mechanical equipment and various chemicals like epoxy resin,furan resin,phenolic resin,etc.are used in the industry to reduce or eliminate this problem.In the present study,a blend of organic and inorganic silicates are used to consolidate loose sand in the presence and absence of crude oil using a core flooding apparatus.The effects of chemical concentration,pH,curing temperature and time,and the presence of residual oil on the consolidation treatment results such as compressive strength and permeability retention,were investigated and optimized.FT-IR and FE-SEM characterization techniques were employed to investigate the interaction between the chemical molecules and the sand grains.The current binding agent exhibited a viscosity of less than 6 cP at room temperature,which facilitates efficient pumping of binding agent into the desired formation through the well bore.The developed mixture demonstrated consolidation properties across all pH conditions.Furthermore,during the experimental investigation,the curing time and temperature was carefully optimized at 12 h and 423.15K,respectively to achieve the highest compressive strength of 2021 psi while achieving the permeability retention of 64%.The current chemical system exhibited improved consolidation capacity and can be effectively utilized for sand consolidation treatment in high-temperature formations.
基金supported by the National Research Foundation of Korea(NRF)–Grants funded by the Ministry of Science,ICT and Future Planning(2014R1A2A2A01004352)the Ministry of Education(2009-0093816),Republic of Korea
文摘A silica supported ionic liquid was synthesized and characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, and thermogravimetric analysis. All these techniques, especially SEM results indicated the presence of well-defined spherical particles having diameters larger than the pristine silica particles, confirming the successful immobilization of the ionic liquid. The prepared silica supported ionic liquid was used in the reductive amination of cyclohexanone under different conditions with different azeotropic mixtures of formic acid and triethyl amine as a hydrogen source. The catalyst showed efficient catalytic performance and excellent yields of N-cyclohexyl amine derivatives in the range of 58% to 84% at 30 °C. After completion of the reaction, the catalyst was easily recovered by simple filtration and reused for another five cycles without any significant impact on product yields. The obtained catalytic performance indicates that the present catalyst is green, very active, and reusable for the reductive amination of cyclohexanone.
文摘This study described a hydrometallurgical method to investigate the separation of rare earth elements(REEs)from rare earth polishing powder wastes(REPPWs)containing large amounts of rare earth oxides with a major phase of CeO2 and minor phases of La2O3,Pr2O3,and Nd2O3 using a process devised by the authors.The suggested approach consisted of five processes:the synthesis of NaR E(SO4)2·xH2O from rare earth oxides in Na2SO4-H2SO4-H2 O solutions(Process 1),the conversion of NaR E(SO4)2·xH2O into RE(OH)3 using NaO H(Process 2),and the oxidation of Ce(OH)3 into Ce(OH)4 using air with O2 injection(Process 3),followed by Processes 4 and 5 for separation of REEs by acid leaching using HCl and H2SO4,respectively.To confirm the high yield of NaR E(SO4)2·xH2O in Process 1,experiments were carried out under various Na2SO4 concentrations(0.4–2.5 mol/L),sulfuric acid concentrations(6–14 mol/L),and reaction temperatures(95–125 oC).In addition,the effect of the pH value on the separation of Ce(OH)4 in HCl-H2 O solutions with Ce(OH)4,La-,Pr-,and Nd(OH)3 in Process 4 was also investigated.On the basis of above results,the possibility of effective separation of REEs from REPPWs could be confirmed.
基金Japan Aluminum Association for the financial aid extended to this study
文摘A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, variations in the texture and Lankford value of a 1070 aluminum sheet rolled by the cone-shaped roll were investigated. Rolling with the cone-shaped roll was found to impose intense shear strain at the edges of the specimen, specifically near the surface. The shear directions in the left and right portions of the specimen were opposite to each other. The surface and middle layer of the specimen rolled by the cone-shaped roll and the reference specimen were characterized by a shear texture and typical recrystallization texture components, respectively. Notably, the specimen rolled by the cone-shaped roll exhibited smaller texture intensity than the reference specimen, especially at the surface, and the shear texture-components were observed at relatively deeper positions. As a result of Lankford value measurements, the specimen rolled with the cone-shape roll exhibited a smaller planar anisotropy than the reference specimen and an average Lankford value close to unity, which are likely due to the texture modifications introduced during rolling with the cone-shaped roll.
文摘The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen electrolytic cell equipped with an electrostatic-induction potential-superposed water electrolytic cell that provides a stoichiometric H2-O2 fuel mixture during operation of the vehicle. This generator functions with zero power input, zero matter input and zero emission due to the so-called "zero power input" electrostatic-to-chemical energy conversion occurring in the electrolytic cell. Here, theoretical simulations were performed to verify the target performance of such generators, assuming a pair of FC (fuel cell) and electrolytic cell stacks, both of which are commercially available.
文摘Opening up new and unlimited avenues in the biomedical field,tissue engineering and regenerative medicine,the electrospinning process is considered as a versatile and the most preferred technique for the fabrication of nanofibers.These tailor-designed nanofibers provide a desirable and bio-inspired physiological niche to cells for better attachment and subsequent proliferation.In this review,an attempt is made to explain the importance of various topological and morphological parameters of nanofibrous scaffolds for efficient bio-mimicking.Some novel approaches(e.g.,appropriate functionalization and extracellular matrix derived from decellularization)utilized for better mimicking and exponential growth of regenerating tissues are also discussed.Furthermore,this review highlights the important parameters necessary for the attachment,proliferation and differentiation of the mesenchymal stem cells for tissue regeneration.The importance of growth factors and their role after introducing the electrospinning techniques for efficient delivery and their role in the proliferation of mesenchymal stem cells in the different specific lineage(e.g.,tenogenic,chondrogenic,neurogenic and osteogenic differentiation)are discussed.
基金supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No.NRF 2017R1D1A1B03036324)supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP)the Ministry of Trade,Industry & Energy (MOTIE) of the Republic of Korea (No.20174010201160)
文摘The development of carbon dioxide(CO_2) sorbents that can operate at elevated temperatures is significant for the advancement of pre-combustion capture technologies.Recently, promoter-based systems composed of alkali/alkaline earth metal nitrates and/or carbonates have been considered as next-generation solid sorbents due to their improved CO_2 uptake and kinetics. However, obtaining stable MgO sorbents against temperature swing regeneration still remained challenging. Herein, we report MgO-TiO_2 solid sorbents promoted by eutectic mixture(KNO_3 and LiNO_3) for elevated temperature CO_2 sorption. The developed sorbents show improved CO_2 sorption capacity, which may be attributed to the alternative CO_2 sorption pathway provided by the ionization of highly dispersed MgO in the eutectic mixture. The MgO-TiO_2 framework was also shown to assist in retaining the MgO configuration by constraining its interaction with CO_2. Furthermore, it is demonstrated that constructing composite structures is essential to improve the CO_2 sorption characteristics,mainly recyclability, at elevated temperatures. The developed promoter integrated sorbents showed exceptionally high CO_2 sorption capacity of > 30 wt.% at an elevated temperature(300°C) with pronounced stability under temperature swing operation.