The effects of trace addition of Al on the microstructure and mechanical properties of the as-extruded Mg-6Zn-0.5Er alloy were investigated in the present investigation.The results showed that the trace addition of Al...The effects of trace addition of Al on the microstructure and mechanical properties of the as-extruded Mg-6Zn-0.5Er alloy were investigated in the present investigation.The results showed that the trace addition of Al affected the mechanical properties significantly.The elongation of the extruded alloy was improved markedly from 17 to 25%with the trace addition of Al.It is suggested that the improvement of ductility was mainly attributed to the modification of basal texture of the as-extruded alloy,resulting from the complete dynamic recrystallization due to the trace addition of Al.In addition,the existence of the complete dynamic recrystallization led to an obvious increase in the number fraction of high angle grain boundaries,the average misorientation angle and Schmid factors for the(0001)1120 slip,which also have contributed to the improvement of ductility.展开更多
The continuous use of chemical dyes in various industries,and their discharge into industrial effluents,results in severe problems to human life and water pollution.Laccases have the ability to decolorize dyes and tox...The continuous use of chemical dyes in various industries,and their discharge into industrial effluents,results in severe problems to human life and water pollution.Laccases have the ability to decolorize dyes and toxic chemicals in industrial effluents as green biocatalysts.Their possible industrial applications have been limited by poor reusability,low stability,and loss of free laccase action.In this research,lac-case was immobilized on zeolitic imidazolate framework coated multi-walled carbon nanotubes(Laccase@ZIF-8@MWCNTs)via metal affinity adsorption to develop an easy separable and stable enzyme.The optimum reaction conditions for immobilized laccase are at a pH of 3.0 and a temperature of 60℃.The immobilized laccase was enhanced in storage and thermal stability.The results indicated that Laccase@ZIF-8@MWCNTs still maintained 68%of its original activity after 10 times of repeated use.Most importantly,the biocatalytic system was applied for decolorization of different dyes(20 mg·L^(-1))without a mediator,and up to 97.4%for Eriochrome black T and 95.6%Acid red 88 was achieved in 25 min.Biocatalysts with these properties may be used in a variety of environmental and industrial applications.展开更多
Unspecific peroxygenases exhibit high activity for the selective oxyfunctionalization of inert C(sp3)–H bonds using only H_(2)O_(2) as a clean oxidant,while also exhibiting sensitivity to H_(2)O_(2) concentration.CdS...Unspecific peroxygenases exhibit high activity for the selective oxyfunctionalization of inert C(sp3)–H bonds using only H_(2)O_(2) as a clean oxidant,while also exhibiting sensitivity to H_(2)O_(2) concentration.CdS-based semiconductors are promising for the photosynthesis of H_(2)O_(2) owing to their adequately negative potential for oxygen reduction reaction via a proton-coupled electron transfer process,however,they suffer from fast H_(2)O_(2) decomposition on the surface of pristine CdS.Therefore,[Cp*Rh(bpy)H_(2)O]2+,a highly selective proton-coupled electron transfer catalyst,was anchored onto a supramolecular polymer-grafted CdS nanoflower to construct an efficient integrated photocatalyst for generating H_(2)O_(2),mitigating the surface issue of pristine CdS,increasing light absorption,accelerating photonic carrier separation,and enhancing oxygen reduction reaction selectivity to H_(2)O_(2).This photocatalyst promoted the light driven H_(2)O_(2) generation rate up to 1345μmol·L^(-1)·g^(-1)·h^(-1),which was 2.4 times that of pristine CdS.The constructed heterojunction photocatalyst could supply H_(2)O_(2) in situ for nonspecific peroxygenases to catalyze the C–H oxyfunctionalization of ethylbenzene,achieving a yield of 81%and an ee value of 99%under optimum conditions.A wide range of substrates were converted to the corresponding chiral alcohols using this photo-enzyme catalytic system,achieving the corresponding chiral alcohols in good yield(51%–88%)and excellent enantioselectivity(90%–99%ee).展开更多
The first research and experimental results obtained in China of high-accuracy radiometric calibration based on cryogenic radiometer are reported. Uncertainties of cryogenic radiometer and trap detectors at 7 waveleng...The first research and experimental results obtained in China of high-accuracy radiometric calibration based on cryogenic radiometer are reported. Uncertainties of cryogenic radiometer and trap detectors at 7 wavelengths in the visible spectrum (488-786 nm) were less than 0.023% and 0.035% respectively, which proved the reasonability and possibility of establishing and transferring high-accuracy radiometric standards based on detectors.展开更多
The worldwide application of organophosphorus pesticides(OPs)has promoted agricultural development,but their gradual accumulation in soil and water can seriously affect the central nervous system of humans and other m...The worldwide application of organophosphorus pesticides(OPs)has promoted agricultural development,but their gradual accumulation in soil and water can seriously affect the central nervous system of humans and other mammals.Organophosphorus hydrolase(OPH)is an effective enzyme that can catalyze the degradation of the residual OPs.However,the degradation products such as p-nitrophenol(p-NP)is still toxic.Thus,it is of great significance to develop a multi-functional support that can be simultaneously used for the immobilization of OPH and the further degradation of p-NP.Herein,a visible light assisted enzyme-photocatalytic integrated catalyst was constructed by immobilizing OPH on hollow structured Au-TiO_(2)(named OPH@H-Au-TiO_(2))for the degradation of OPs.The obtained OPH@H-Au-TiO_(2)can degrade methyl parathion to p-NP by OPH and then degrade p-NP to hydroquinone with low toxicity by using H-Au-TiO_(2)under visible light.OPH molecules were immobilized on HAu-TiO_(2)through adsorption method to prepare OPH@H-Au-TiO_(2).After 2.5 h of reaction,methyl parathion is completely degraded,and about 82.64%of the generated p-NP is further degraded into hydroquinone.After reused for 4 times,the OPH@H-Au-TiO_(2)retains more than 80%of the initial degradation activity.This research presents a new insight in designing and constructing multi-functional biocatalyst,which greatly expands the application scenarios and industrial value of enzyme catalysis.展开更多
Formations of clots were found inside the hydrodynamic bearings of the left ventricular assisted devices (LVADs) and caused tremendous risks to the long-term use of these devices. For the hydrodynamic bearings used in...Formations of clots were found inside the hydrodynamic bearings of the left ventricular assisted devices (LVADs) and caused tremendous risks to the long-term use of these devices. For the hydrodynamic bearings used in the LVAD, not only the lubrication status but also the motion of the blood cells in the bearing will take great effect on the performance of the device. Based on the analysis of the hydrodynamic pressures distribution and the flowing trajectory of red blood cells in the lubrication film, the bearing is designed in a region where enough hydrodynamic pressure is generated to float the rotor to reduce the wear, and the entrainment of red blood cells in the gap of the bearing can be prevented to avoid the formation of clots.展开更多
The hollow spherical covalent organic frameworks(COFs)have a wide application prospect thanks to their special structures.However,the controllable synthesis of uniform and stable hollow COFs is still a challenge.We he...The hollow spherical covalent organic frameworks(COFs)have a wide application prospect thanks to their special structures.However,the controllable synthesis of uniform and stable hollow COFs is still a challenge.We herein propose a self-templated method for the preparation of hollow COFs through the Ostwald ripening mechanism under ambient conditions,which avoids most disadvantages of the commonly used hard-templating and soft-templating methods.A detailed time-dependent study reveals that the COFs are transformed from initial spheres to hollow spheres because of the inside-out Ostwald ripening process.The obtained hollow spherical COFs have high crystallinity,specific surface area(2,036 m^(2)·g^(−1)),stability,and single-batch yield.Thanks to unique hollow structure,clear through holes,and hydrophobic pore environment of the hollow spherical COFs,the obtained immobilized lipase(BCL@H-COF-OMe)exhibits higher thermostability,polar organic solvent tolerance,and reusability.The BCL@H-COF-OMe also shows higher catalytic performance than the lipase immobilized on non-hollow COF and free lipase in the kinetic resolution of secondary alcohols.This study provides a simple approach for the preparation of hollow spherical COFs,and will promote the valuable research of COFs in the field of biocatalysis.展开更多
In situ encapsulation is an effective way to synthesize enzyme@metal–organic framework biocatalysts;however,it is limited by the conditions of metal–organic framework synthesis and its acid-base stability.Herein,a b...In situ encapsulation is an effective way to synthesize enzyme@metal–organic framework biocatalysts;however,it is limited by the conditions of metal–organic framework synthesis and its acid-base stability.Herein,a biocatalytic platform with improved acid-base stability was constructed via a one-pot method using bismuth-ellagic acid as the carrier.Bismuth-ellagic acid is a green phenol-based metal–organic framework whose organic precursor is extracted from natural plants.After encapsulation,the stability,especially the acid-base stability,of amyloglucosidases@bismuth-ellagic acid was enhanced,which remained stable over a wide pH range(2–12)and achieved multiple recycling.By selecting a suitable buffer,bismuth-ellagic acid can encapsulate different types of enzymes and enable interactions between the encapsulated enzymes and cofactors,as well as between multiple enzymes.The green precursor,simple and convenient preparation process provided a versatile strategy for enzymes encapsulation.展开更多
基金the Beijing Natural Science Foundation(2142005)the Natural Science Foundation of China(51401005)RiXin Talents Plan of Beijing University of Technology(2014-RX-L07).
文摘The effects of trace addition of Al on the microstructure and mechanical properties of the as-extruded Mg-6Zn-0.5Er alloy were investigated in the present investigation.The results showed that the trace addition of Al affected the mechanical properties significantly.The elongation of the extruded alloy was improved markedly from 17 to 25%with the trace addition of Al.It is suggested that the improvement of ductility was mainly attributed to the modification of basal texture of the as-extruded alloy,resulting from the complete dynamic recrystallization due to the trace addition of Al.In addition,the existence of the complete dynamic recrystallization led to an obvious increase in the number fraction of high angle grain boundaries,the average misorientation angle and Schmid factors for the(0001)1120 slip,which also have contributed to the improvement of ductility.
基金supported by the National Natural Science Foundation of China(Nos.21576068,21276060,21276062,and 21306039)the Natural Science Foundation of Tianjin City(16JCY-BJC19800)+3 种基金the Natural Science Foundation of Hebei Province(B2015202082,B2016202027,and B2020202036)the Science and Technology Program Project of Tianjin(20YDTPJC00260)the Program for Top 100 Innovative Talents in Colleges and Universities of Hebei Province(SLRC2017029)Hebei High level personnel of support program(A2016002027).
文摘The continuous use of chemical dyes in various industries,and their discharge into industrial effluents,results in severe problems to human life and water pollution.Laccases have the ability to decolorize dyes and toxic chemicals in industrial effluents as green biocatalysts.Their possible industrial applications have been limited by poor reusability,low stability,and loss of free laccase action.In this research,lac-case was immobilized on zeolitic imidazolate framework coated multi-walled carbon nanotubes(Laccase@ZIF-8@MWCNTs)via metal affinity adsorption to develop an easy separable and stable enzyme.The optimum reaction conditions for immobilized laccase are at a pH of 3.0 and a temperature of 60℃.The immobilized laccase was enhanced in storage and thermal stability.The results indicated that Laccase@ZIF-8@MWCNTs still maintained 68%of its original activity after 10 times of repeated use.Most importantly,the biocatalytic system was applied for decolorization of different dyes(20 mg·L^(-1))without a mediator,and up to 97.4%for Eriochrome black T and 95.6%Acid red 88 was achieved in 25 min.Biocatalysts with these properties may be used in a variety of environmental and industrial applications.
基金supported by the National Natural Science Foundation of China(Grant No.22378096)the Natural Science Foundation of Hebei Province(Grant No.B2023202014)+1 种基金the Science Technology Research Project of Higher Education of Hebei Province(Grant Nos.QN2021045,and QN2023207)the Tianjin Science and Technology Project(Grant No.22KPHDRC00260).
文摘Unspecific peroxygenases exhibit high activity for the selective oxyfunctionalization of inert C(sp3)–H bonds using only H_(2)O_(2) as a clean oxidant,while also exhibiting sensitivity to H_(2)O_(2) concentration.CdS-based semiconductors are promising for the photosynthesis of H_(2)O_(2) owing to their adequately negative potential for oxygen reduction reaction via a proton-coupled electron transfer process,however,they suffer from fast H_(2)O_(2) decomposition on the surface of pristine CdS.Therefore,[Cp*Rh(bpy)H_(2)O]2+,a highly selective proton-coupled electron transfer catalyst,was anchored onto a supramolecular polymer-grafted CdS nanoflower to construct an efficient integrated photocatalyst for generating H_(2)O_(2),mitigating the surface issue of pristine CdS,increasing light absorption,accelerating photonic carrier separation,and enhancing oxygen reduction reaction selectivity to H_(2)O_(2).This photocatalyst promoted the light driven H_(2)O_(2) generation rate up to 1345μmol·L^(-1)·g^(-1)·h^(-1),which was 2.4 times that of pristine CdS.The constructed heterojunction photocatalyst could supply H_(2)O_(2) in situ for nonspecific peroxygenases to catalyze the C–H oxyfunctionalization of ethylbenzene,achieving a yield of 81%and an ee value of 99%under optimum conditions.A wide range of substrates were converted to the corresponding chiral alcohols using this photo-enzyme catalytic system,achieving the corresponding chiral alcohols in good yield(51%–88%)and excellent enantioselectivity(90%–99%ee).
文摘The first research and experimental results obtained in China of high-accuracy radiometric calibration based on cryogenic radiometer are reported. Uncertainties of cryogenic radiometer and trap detectors at 7 wavelengths in the visible spectrum (488-786 nm) were less than 0.023% and 0.035% respectively, which proved the reasonability and possibility of establishing and transferring high-accuracy radiometric standards based on detectors.
基金supported by the National Natural Science Foundation of China(Nos.21901058,21908040,and 21878068)Tianjin Enterprise Science and Technology Commissioner,China(21YDTPJC00810)+2 种基金Science Technology Research Project of Higher Education of Hebei Province,China(QN2021045)Hebei Province Postgraduate Innovation Funding Project,China(CXZZSS2021027)National College Student’s Science and Technology Innovation Project,China(202010080038)。
文摘The worldwide application of organophosphorus pesticides(OPs)has promoted agricultural development,but their gradual accumulation in soil and water can seriously affect the central nervous system of humans and other mammals.Organophosphorus hydrolase(OPH)is an effective enzyme that can catalyze the degradation of the residual OPs.However,the degradation products such as p-nitrophenol(p-NP)is still toxic.Thus,it is of great significance to develop a multi-functional support that can be simultaneously used for the immobilization of OPH and the further degradation of p-NP.Herein,a visible light assisted enzyme-photocatalytic integrated catalyst was constructed by immobilizing OPH on hollow structured Au-TiO_(2)(named OPH@H-Au-TiO_(2))for the degradation of OPs.The obtained OPH@H-Au-TiO_(2)can degrade methyl parathion to p-NP by OPH and then degrade p-NP to hydroquinone with low toxicity by using H-Au-TiO_(2)under visible light.OPH molecules were immobilized on HAu-TiO_(2)through adsorption method to prepare OPH@H-Au-TiO_(2).After 2.5 h of reaction,methyl parathion is completely degraded,and about 82.64%of the generated p-NP is further degraded into hydroquinone.After reused for 4 times,the OPH@H-Au-TiO_(2)retains more than 80%of the initial degradation activity.This research presents a new insight in designing and constructing multi-functional biocatalyst,which greatly expands the application scenarios and industrial value of enzyme catalysis.
基金This work is supported by the National Key R&D Program of China(2017YFCO111105)the funding of State Key Laboratory of Tribology,China(SKLT2018B03).
文摘Formations of clots were found inside the hydrodynamic bearings of the left ventricular assisted devices (LVADs) and caused tremendous risks to the long-term use of these devices. For the hydrodynamic bearings used in the LVAD, not only the lubrication status but also the motion of the blood cells in the bearing will take great effect on the performance of the device. Based on the analysis of the hydrodynamic pressures distribution and the flowing trajectory of red blood cells in the lubrication film, the bearing is designed in a region where enough hydrodynamic pressure is generated to float the rotor to reduce the wear, and the entrainment of red blood cells in the gap of the bearing can be prevented to avoid the formation of clots.
基金This work was supported by the National Natural Science Foundation of China(Nos.22078081,21908040,21901058,and 22178083)the Natural Science Foundation of Hebei Province(Nos.B2020202021 and B2019202216)+2 种基金Key Research and Development Program of Hebei Province(No.20372802D)Open Project Funding of the State Key Laboratory of Biocatalysis and Enzyme Engineering(No.SKLBEE2020011)the Natural Science Foundation of Tianjin(No.20JCYBJC00530).
文摘The hollow spherical covalent organic frameworks(COFs)have a wide application prospect thanks to their special structures.However,the controllable synthesis of uniform and stable hollow COFs is still a challenge.We herein propose a self-templated method for the preparation of hollow COFs through the Ostwald ripening mechanism under ambient conditions,which avoids most disadvantages of the commonly used hard-templating and soft-templating methods.A detailed time-dependent study reveals that the COFs are transformed from initial spheres to hollow spheres because of the inside-out Ostwald ripening process.The obtained hollow spherical COFs have high crystallinity,specific surface area(2,036 m^(2)·g^(−1)),stability,and single-batch yield.Thanks to unique hollow structure,clear through holes,and hydrophobic pore environment of the hollow spherical COFs,the obtained immobilized lipase(BCL@H-COF-OMe)exhibits higher thermostability,polar organic solvent tolerance,and reusability.The BCL@H-COF-OMe also shows higher catalytic performance than the lipase immobilized on non-hollow COF and free lipase in the kinetic resolution of secondary alcohols.This study provides a simple approach for the preparation of hollow spherical COFs,and will promote the valuable research of COFs in the field of biocatalysis.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.22178083,22078081 and 21878068)the Natural Science Foundation of Tianjin China(Grant No.20JCYBJC00530)+3 种基金the Hebei Key Research and Development Project(Grant No.20372802D)Open Funding Project of the State Key Laboratory of Biocatalysis and Enzyme Engineering(Grant No.SKLBEE2020011)Science Technology Research Project of Higher Education of Hebei Province(Grant No.QN2021045)Tianjin Enterprise Science and Technology Commissioner Project(Grant No.21YDTPJC00810).
文摘In situ encapsulation is an effective way to synthesize enzyme@metal–organic framework biocatalysts;however,it is limited by the conditions of metal–organic framework synthesis and its acid-base stability.Herein,a biocatalytic platform with improved acid-base stability was constructed via a one-pot method using bismuth-ellagic acid as the carrier.Bismuth-ellagic acid is a green phenol-based metal–organic framework whose organic precursor is extracted from natural plants.After encapsulation,the stability,especially the acid-base stability,of amyloglucosidases@bismuth-ellagic acid was enhanced,which remained stable over a wide pH range(2–12)and achieved multiple recycling.By selecting a suitable buffer,bismuth-ellagic acid can encapsulate different types of enzymes and enable interactions between the encapsulated enzymes and cofactors,as well as between multiple enzymes.The green precursor,simple and convenient preparation process provided a versatile strategy for enzymes encapsulation.
