Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as...Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation.Here,we review the CO_(2)reduction with active materials prepared by exsolution.The fundamental of exsolution was summarized in terms of mechanism and models,materials,and driven forces.The advances in the exsolved materials used in hightemperature CO_(2)electrolysis were catalogued into tailored interfaces,synergistic effects on alloy particles,phase transition,reversibility and electrochemical switching.展开更多
Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neu...Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neurological diseases.Herein,we applied Raman spectroscopy to study the Ni(II)ion effect on kinetics of amyloid fibrillation of hen egg white lysozyme(HEWL)in thermal and acidic conditions.Using the well-known Raman indicators for protein tertiary and secondary structures,we monitored and analyzed the concentration effect of Ni(II)ions on the unfolding of tertiary structures and the transformation of sec-ondary structures.The experimental evidence validates the accelerator role of the metal ion in the kinetics.Notably,the additional analysis of the amide I band profile,combined with thioflavin-T fluorescence assays,clearly indicates the inhibitory effect of Ni(II)ions on the formation of amyloid fibrils with organizedβ-sheets structures.Instead,a more significant promotion influence is affirmed on the assembly into other aggregates with disordered struc-tures.The present results provide rich information about the specific metal-mediated protein fibrillation.展开更多
NiO_(x)-based inverted perovskite solar cells(PSCs)havepresented great potential toward low-cost,highly efficient and stablenext-generation photovoltaics.However,the presence of energy-levelmismatch and contact-interf...NiO_(x)-based inverted perovskite solar cells(PSCs)havepresented great potential toward low-cost,highly efficient and stablenext-generation photovoltaics.However,the presence of energy-levelmismatch and contact-interface defects between hole-selective contacts(HSCs)and perovskite-active layer(PAL)still limits device efficiencyimprovement.Here,we report a graded configuration based on bothinterface-cascaded structures and p-type molecule-doped compositeswith two-/three-dimensional formamidinium-based triple-halideperovskites.We find that the interface defects-induced non-radiativerecombination presented at HSCs/PAL interfaces is remarkably suppressedbecause of efficient hole extraction and transport.Moreover,astrong chemical interaction,halogen bonding and coordination bondingare found in the molecule-doped perovskite composites,whichsignificantly suppress the formation of halide vacancy and parasitic metallic lead.As a result,NiO_(x)-based inverted PSCs present a power-conversion-efficiency over 23%with a high fill factor of 0.84 and open-circuit voltage of 1.162 V,which are comparable to the best reported around 1.56-electron volt bandgap perovskites.Furthermore,devices with encapsulation present high operational stability over 1,200 h during T_(90) lifetime measurement(the time as a function of PCE decreases to 90%of its initial value)under 1-sun illumination in ambient-air conditions.展开更多
The large inertia of a traditional power system slows down system's frequency response but also allows decent time for controlling the system.Since an autonomous renewable microgrid usually has much smaller inerti...The large inertia of a traditional power system slows down system's frequency response but also allows decent time for controlling the system.Since an autonomous renewable microgrid usually has much smaller inertia,the control system must be very fast and accurate to fight against the small inertia and uncertainties.To reduce the demanding requirements on control,this paper proposes to increase the inertia of photovoltaic(PV) system through inertia emulation.The inertia emulation is realized by controlling the charging/discharging of the direct current(DC)-link capacitor over a certain range and adjusting the PV generation when it is feasible and/or necessary.By well designing the inertia,the DC-link capacitor parameters and the control range,the negative impact of inertia emulation on energy efficiency can be reduced.The proposed algorithm can be integrated with distributed generation setting algorithms to improve dynamic performance and lower implementation requirements.Simulation studies demonstrate the effectiveness of the proposed solution.展开更多
Ultrasonic welding is an effective ways to achieve a non-reactive/immiscible heterogeneous metal connection, such as the connection of magnesium alloy and titanium alloy. But the thermal mechanism of magnesium alloy/t...Ultrasonic welding is an effective ways to achieve a non-reactive/immiscible heterogeneous metal connection, such as the connection of magnesium alloy and titanium alloy. But the thermal mechanism of magnesium alloy/titanium alloy ultrasonic welding has not been defined clearly. In this paper, the experimental and the finite element analysis were adopted to study the thermal mechanism during welding. Through the test, the temperature variation law during the welding process is obtained, and the accuracy of the finite element model is verified. The microscopic analysis indicates that at the welding time of 0.5 s, the magnesium alloy in the center of the solder joint is partially melted and generates the liquid phase. Through the finite element analysis, the friction coefficient of the magnesium–titanium ultrasonic welding interface can be considered as an average constant value of 0.28. The maximum temperature at the interface can exceed 600 ℃ to reach the melting point temperature of the magnesium alloy. The plastic deformation begins after 0.35 s and occurs at the magnesium side at the center of the interface.展开更多
L-Amino acid deaminase(LAAD) is a key enzyme in the deamination of L-valine(L-val) to produce α-ketoisovalerate(KIV). However, the product inhibition of LAAD is a major hindrance to industrial KIV production.In the p...L-Amino acid deaminase(LAAD) is a key enzyme in the deamination of L-valine(L-val) to produce α-ketoisovalerate(KIV). However, the product inhibition of LAAD is a major hindrance to industrial KIV production.In the present study, a combination strategy of modification of flexible loop regions around the product binding site and the avoidance of dramatic change of main-chain dynamics was reported to reduce the product inhibition.The four mutant PM-LAAD^(M4)(PM-LAAD^(S98A/T105A/S106A/L341A)) achieved a 6.2-fold higher catalytic efficiency and an almost 6.7-fold reduction in product inhibition than the wild-type enzyme. Docking experiments suggested that weakened interactions between the product and enzyme, and the flexibility of the "lid" structure relieved LAAD product inhibition. Finally, the whole-cell biocatalyst PM-LAAD^(M4) has been applied to KIV production,the titer and conversion rate of KIV from L-val were 98.5 g·L^-1 and 99.2% at a 3-L scale, respectively. These results demonstrate that the newly engineered catalyst can significantly reduce the product inhibition, that making KIV a prospective product by bioconversion method, and also provide the understanding of the mechanism of the relieved product inhibition of PM-LAAD.展开更多
Coking coal dust is extremely hydrophobic;therefore,combination with droplets in the air is difficult and dust suppression is challenging.Here,a dust suppressant spray for coking coal dust was studied in order to impr...Coking coal dust is extremely hydrophobic;therefore,combination with droplets in the air is difficult and dust suppression is challenging.Here,a dust suppressant spray for coking coal dust was studied in order to improve of the combination of droplets and coking coal dust.Based on monomer optimization and compounding analysis,two surfactant monomers,fatty alcohol ether sodium sulfate(AES)and sodium dodecyl benzene sulfonate(SDBS)were selected as the surfactant components of the dust suppressant.The surfactant monomers were combined with four inorganic salts and the reverse osmosis moisture absorption of each solution was determined.By combining the reverse osmosis moisture absorption values with the water retention experimental results,CaCl_(2)was identified as the optimal inorganic salt additive for the dust suppressant.Finally,the optimal concentration of each component was obtained using orthogonal experimental design i.e.,AES(0.03%),SDBS(0.05%),and CaCl_(2)(0.4%).The dust suppressant solution formulated using this method had a high moisture absorption capacity and excellent performance.展开更多
For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of S...For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.展开更多
We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separati...We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separation between the DQD is smaller than the Fermi wavelength in the 2DEGs, the asymmetry in the dots' energy levels leads to pronounced quantum interference effects characterized by the Dicke line-shape of the conductance, which are sensitive to the properties of the 2DEGs. The magnitude of the thermopower, which denotes the generated voltage in response to an infinitesimal temperature difference between the two 2DEGs under vanishing charge current, will be obviously enhanced by the Dicke effect. The application of the in-plane magnetic field results in the polarization of the spin-up and spin-down conductances and thermopowers, and enables an efficient spin-filter device in addition to a tunable pure spin thermopower in the absence of its charge counterpart.展开更多
The fascinating Dirac cone in honeycomb graphene,which underlies many unique electronic properties,has inspired the vast endeavors on pursuing new two-dimensional(2D)Dirac materials.Based on the density functional the...The fascinating Dirac cone in honeycomb graphene,which underlies many unique electronic properties,has inspired the vast endeavors on pursuing new two-dimensional(2D)Dirac materials.Based on the density functional theory method,a 2D material Zn3Si2 of honeycomb transition-metal silicide with intrinsic Dirac cones has been predicted.The Zn3Si2 monolayer is dynamically and thermodynamically stable under ambient conditions.Importantly,the Zn3Si2 monolayer is a room-temperature 2D Dirac material with a spin-orbit coupling energy gap of 1.2 meV,which has an intrinsic Dirac cone arising from the special hexagonal lattice structure.Hole doping leads to the spin polarization of the electron,which results in a Dirac half-metal feature with single-spin Dirac fermion.This novel stable 2D transition-metal-silicon-framework material holds promises for electronic device applications in spintronics.展开更多
The present study evaluated risk factors related to persistent atrial fibrillation(AF)at discharge(AF-d)and recurrent atrial fibrillation(rAF)and all-cause death after the maze IV procedure.Two hundred nineteen patien...The present study evaluated risk factors related to persistent atrial fibrillation(AF)at discharge(AF-d)and recurrent atrial fibrillation(rAF)and all-cause death after the maze IV procedure.Two hundred nineteen patients(63 female,aged 52.5±8.8 years)with valve disease and persistent AF undergoing valve surgery and the maze IV procedure in our center between 2015 and 2016 were included.Baseline demographic and clinical data were obtained by review of medical records.The median follow-up period was 27 months(interquartile range 21-34 months)in our patient cohort.The primary end point was all-cause death.The secondary end point was AF-d or rAF.rAF is defined as AF recurrence at 3 months or later after the procedure.Twenty-eight patients(12.8%)died during follow-up.Multiple logistic regression analysis showed that thrombocytopenia,elevated serum total bilirubin level,a larger right atrium,AF-d,and rAF were independent determinants for all-cause death after the maze IV procedure after adjustment for age,sex,and clinical covariates,including New York Heart Association class III/IV disease,hypertension,and aortic regurgitation,while valvular disease duration and left atrial diameter greater than 80.5 mm were independent determinants for AF-d,and thrombocytopenia,elevated serum total bilirubin level,higher mean pulmonary artery pressure,and AF-d were independent predictors for rAF.In conclusion,thrombocytopenia,elevated serum total bilirubin level,an enlarged right atrium,AF-d,and rAF are independent predictors of all-cause death in patients undergoing the maze IV procedure.展开更多
Photoacoustic imaging(PAI)breaks through the optical di®usion limit by making use of the PA e®ect.By converting incident photons into ultrasonic waves,PAI combines high contrast of optical imaging and high s...Photoacoustic imaging(PAI)breaks through the optical di®usion limit by making use of the PA e®ect.By converting incident photons into ultrasonic waves,PAI combines high contrast of optical imaging and high spatial resolution in depth tissue of ultrasound imaging in a single imaging modality.This imaging modality has now shown potential for molecular imaging,which enables visualization of biological processes with systemically introduced functional nanoparticles.In the current review,the potentials of di®erent optical nanoprobes as PAI contrast agents were elucidated and discussed.展开更多
The use of abundant and cheap one carbon(C1)feedstocks to produce value-added chemicals is an important approach for achieving carbon neutrality and tackling environmental problems.The conversion of C1 feedstocks to h...The use of abundant and cheap one carbon(C1)feedstocks to produce value-added chemicals is an important approach for achieving carbon neutrality and tackling environmental problems.The conversion of C1 feedstocks to high-value chemicals is dependent on efficient C1 assimilation pathways and microbial chassis adapted for efficient incorporation.Here,we opted to summarize the natural and synthetic C1 assimilation pathways and their key factors for metabolizing C1 feedstock.Accordingly,we discussed the metabolic engineering strategies for enabling the microbial utilization of C1 feedstocks for the bioproduction of value-added chemicals.In addition,we highlighted future perspectives of C1-based biomanufacturing for achieving a low-carbon footprint for the biosynthesis of chemicals.展开更多
Microbial biorefineries to produce chemicals from renewable feedstock provides attractive advantages,including mild reaction conditions and sustainable manufacturing.However,low-efficiency biorefineries always result ...Microbial biorefineries to produce chemicals from renewable feedstock provides attractive advantages,including mild reaction conditions and sustainable manufacturing.However,low-efficiency biorefineries always result in an uncompetitive biological process compared to the current petrochemical process.Thus,improving microbial capacity to maximize product yield,productivity,and titer has been recognized as a central goal for bioengineers and biochemists.The knowledge of cellular biochemistry has enabled the regulation of microbial physiology to couple with chemical production.The rapid development in metabolic engineering provides diverse strategies to enhance the efficiency of chemical biosynthesis pathways.New synthetic biology tools as well as novel regulatory targets also offer the opportunity to improve biorefinery environmental adaptivity.In this review,the recent advances in building efficient biorefineries were showcased.In addition,the challenges and future perspectives of microbial host engineering for increased microbial capacity of a biorefinery were discussed.展开更多
The increasing shortage of fossil resources and environmental pollution has renewed interest in the synthesis of value-added biochemicals from methanol.However,most of native or synthetic methylotrophs are unable to a...The increasing shortage of fossil resources and environmental pollution has renewed interest in the synthesis of value-added biochemicals from methanol.However,most of native or synthetic methylotrophs are unable to assimilate methanol at a sufficient rate to produce biochemicals.Thus,the performance of methylotrophs still needs to be optimized to meet the demands of industrial applications.In this review,we provide an in-depth discussion on the properties of natural and synthetic methylotrophs,and summarize the natural and synthetic methanol assimilation pathways.Further,we discuss metabolic engineering strategies for enabling microbial utilization of methanol for the bioproduction of value-added chemicals.Finally,we highlight the potential of microbial engineering for methanol assimilation and offer guidance for achieving a low-carbon footprint for the biosynthesis of chemicals.展开更多
基金This work is supported by the National Key Research and Development Program of China(No.2021YFA0718900)the National Natural Science Foundation of China(No.NSCF52102137)+1 种基金We also appreciate the support from Tsinghua University Initiative Scientific Research Program and Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2022006EPSRC)the Institute for Guo Qiang,Tsinghua University(2020GQG1003).
文摘Electrochemical reduction of CO_(2)into valuable fuels and chemicals has become a contemporary research area,where the heterogeneous catalyst plays a critical role.Metal nanoparticles supported on oxides performing as active sites of electrochemical reactions have been the focus of intensive investigation.Here,we review the CO_(2)reduction with active materials prepared by exsolution.The fundamental of exsolution was summarized in terms of mechanism and models,materials,and driven forces.The advances in the exsolved materials used in hightemperature CO_(2)electrolysis were catalogued into tailored interfaces,synergistic effects on alloy particles,phase transition,reversibility and electrochemical switching.
基金supported by the National Natural Science Foundation of China(No.22073088,No.22027801 and No.21873089).
文摘Nickel,an important transi-tion metal element,is one of the trace elements for hu-man body and has a crucial impact on life and health.Some evidences show the excess exposure to metal ions might be associated with neurological diseases.Herein,we applied Raman spectroscopy to study the Ni(II)ion effect on kinetics of amyloid fibrillation of hen egg white lysozyme(HEWL)in thermal and acidic conditions.Using the well-known Raman indicators for protein tertiary and secondary structures,we monitored and analyzed the concentration effect of Ni(II)ions on the unfolding of tertiary structures and the transformation of sec-ondary structures.The experimental evidence validates the accelerator role of the metal ion in the kinetics.Notably,the additional analysis of the amide I band profile,combined with thioflavin-T fluorescence assays,clearly indicates the inhibitory effect of Ni(II)ions on the formation of amyloid fibrils with organizedβ-sheets structures.Instead,a more significant promotion influence is affirmed on the assembly into other aggregates with disordered struc-tures.The present results provide rich information about the specific metal-mediated protein fibrillation.
基金supported by National Natural Science Foundation of China (62204099)Guangdong Basic and Applied Basic Research Foundation (2020A1515110462)+1 种基金Fundamental Research Funds for the Central Universities (21620347)the Special Funds for College Students’ Innovative Entrepreneurial Training Plan Program
文摘NiO_(x)-based inverted perovskite solar cells(PSCs)havepresented great potential toward low-cost,highly efficient and stablenext-generation photovoltaics.However,the presence of energy-levelmismatch and contact-interface defects between hole-selective contacts(HSCs)and perovskite-active layer(PAL)still limits device efficiencyimprovement.Here,we report a graded configuration based on bothinterface-cascaded structures and p-type molecule-doped compositeswith two-/three-dimensional formamidinium-based triple-halideperovskites.We find that the interface defects-induced non-radiativerecombination presented at HSCs/PAL interfaces is remarkably suppressedbecause of efficient hole extraction and transport.Moreover,astrong chemical interaction,halogen bonding and coordination bondingare found in the molecule-doped perovskite composites,whichsignificantly suppress the formation of halide vacancy and parasitic metallic lead.As a result,NiO_(x)-based inverted PSCs present a power-conversion-efficiency over 23%with a high fill factor of 0.84 and open-circuit voltage of 1.162 V,which are comparable to the best reported around 1.56-electron volt bandgap perovskites.Furthermore,devices with encapsulation present high operational stability over 1,200 h during T_(90) lifetime measurement(the time as a function of PCE decreases to 90%of its initial value)under 1-sun illumination in ambient-air conditions.
文摘The large inertia of a traditional power system slows down system's frequency response but also allows decent time for controlling the system.Since an autonomous renewable microgrid usually has much smaller inertia,the control system must be very fast and accurate to fight against the small inertia and uncertainties.To reduce the demanding requirements on control,this paper proposes to increase the inertia of photovoltaic(PV) system through inertia emulation.The inertia emulation is realized by controlling the charging/discharging of the direct current(DC)-link capacitor over a certain range and adjusting the PV generation when it is feasible and/or necessary.By well designing the inertia,the DC-link capacitor parameters and the control range,the negative impact of inertia emulation on energy efficiency can be reduced.The proposed algorithm can be integrated with distributed generation setting algorithms to improve dynamic performance and lower implementation requirements.Simulation studies demonstrate the effectiveness of the proposed solution.
基金Supported by National Natural Science Foundation of China(Grant Nos.U1764251,51775160)Fundamental Research Funds for the Central Universities of China(Grant No.DUT19LAB24)
文摘Ultrasonic welding is an effective ways to achieve a non-reactive/immiscible heterogeneous metal connection, such as the connection of magnesium alloy and titanium alloy. But the thermal mechanism of magnesium alloy/titanium alloy ultrasonic welding has not been defined clearly. In this paper, the experimental and the finite element analysis were adopted to study the thermal mechanism during welding. Through the test, the temperature variation law during the welding process is obtained, and the accuracy of the finite element model is verified. The microscopic analysis indicates that at the welding time of 0.5 s, the magnesium alloy in the center of the solder joint is partially melted and generates the liquid phase. Through the finite element analysis, the friction coefficient of the magnesium–titanium ultrasonic welding interface can be considered as an average constant value of 0.28. The maximum temperature at the interface can exceed 600 ℃ to reach the melting point temperature of the magnesium alloy. The plastic deformation begins after 0.35 s and occurs at the magnesium side at the center of the interface.
基金financially supported by the national first-class discipline program of Light Industry Technology and Engineering(LITE201820)the Key Technologies Research and Development Program of Jiangsu Province(BE2018623)。
文摘L-Amino acid deaminase(LAAD) is a key enzyme in the deamination of L-valine(L-val) to produce α-ketoisovalerate(KIV). However, the product inhibition of LAAD is a major hindrance to industrial KIV production.In the present study, a combination strategy of modification of flexible loop regions around the product binding site and the avoidance of dramatic change of main-chain dynamics was reported to reduce the product inhibition.The four mutant PM-LAAD^(M4)(PM-LAAD^(S98A/T105A/S106A/L341A)) achieved a 6.2-fold higher catalytic efficiency and an almost 6.7-fold reduction in product inhibition than the wild-type enzyme. Docking experiments suggested that weakened interactions between the product and enzyme, and the flexibility of the "lid" structure relieved LAAD product inhibition. Finally, the whole-cell biocatalyst PM-LAAD^(M4) has been applied to KIV production,the titer and conversion rate of KIV from L-val were 98.5 g·L^-1 and 99.2% at a 3-L scale, respectively. These results demonstrate that the newly engineered catalyst can significantly reduce the product inhibition, that making KIV a prospective product by bioconversion method, and also provide the understanding of the mechanism of the relieved product inhibition of PM-LAAD.
基金The project was supported by the National Natural Science Foundation of China(No.51574123)the Scientific Research Project of Hunan Province Office of Education(No.18A185),which is gratefully acknowledged.
文摘Coking coal dust is extremely hydrophobic;therefore,combination with droplets in the air is difficult and dust suppression is challenging.Here,a dust suppressant spray for coking coal dust was studied in order to improve of the combination of droplets and coking coal dust.Based on monomer optimization and compounding analysis,two surfactant monomers,fatty alcohol ether sodium sulfate(AES)and sodium dodecyl benzene sulfonate(SDBS)were selected as the surfactant components of the dust suppressant.The surfactant monomers were combined with four inorganic salts and the reverse osmosis moisture absorption of each solution was determined.By combining the reverse osmosis moisture absorption values with the water retention experimental results,CaCl_(2)was identified as the optimal inorganic salt additive for the dust suppressant.Finally,the optimal concentration of each component was obtained using orthogonal experimental design i.e.,AES(0.03%),SDBS(0.05%),and CaCl_(2)(0.4%).The dust suppressant solution formulated using this method had a high moisture absorption capacity and excellent performance.
基金financially supported by the Fundamental Research Funds for the Central Universities (JUSRP21915)National Natural Science Foundation of China (22008089, 21878126)+2 种基金Provincial Natural Science Foundation of Jiangsu Province(BK20200622)the key technologies Research&Development Program of Jiangsu Province (BE2018623)the National First-Class Discipline Program of Light Industry Technology and Engineering(LITE2018-20)
文摘For the efficient conversion of L-tyrosine(L-Tyr)to tyrosol,which is an aromatic compound widely used in the pharmaceutical and chemical industries,a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli.Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(CtPDC)as the rate-limiting enzymatic step.In situ product removal(ISPR)strategy with XAD4 resins was explored to avoid product inhibition and further improve tyrosol yield.As a result,the titer and conversion rate of tyrosol obtained were 35.7 g·L^(-1) and 93.6%,respectively,in a 3-L bioreactor.Results presented here provide a potential enzymatic process for industrial production of tyrosol from cheap amino acids.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61274101,51362031,and 11675023)the Innovation Development Fund of China Academy of Engineering Physics(CAEP)(Grant No.ZYCX1921-02)+2 种基金the Presidential Foundation of CAEP(Grant No.YZ2015014)the Initial Project of University of Electronic Science and Technology of China,Zhongshan Institute(Grant No.415YKQ02)Science and Technology Bureau of Zhongshan,China(Grant Nos.417S26 and 180809162197886)
文摘We study the spin-dependent thermopower in a double-quantum-dot(DQD) embedded between the left and right two-dimensional electron gases(2DEGs) in doped quantum wells under an in-plane magnetic field. When the separation between the DQD is smaller than the Fermi wavelength in the 2DEGs, the asymmetry in the dots' energy levels leads to pronounced quantum interference effects characterized by the Dicke line-shape of the conductance, which are sensitive to the properties of the 2DEGs. The magnitude of the thermopower, which denotes the generated voltage in response to an infinitesimal temperature difference between the two 2DEGs under vanishing charge current, will be obviously enhanced by the Dicke effect. The application of the in-plane magnetic field results in the polarization of the spin-up and spin-down conductances and thermopowers, and enables an efficient spin-filter device in addition to a tunable pure spin thermopower in the absence of its charge counterpart.
基金the National Natural Science Foundation of China(Grant Nos.11674136 and 11564022)Yunnan Province for Recruiting High-Caliber Technological Talents,China(Grant No.1097816002)+3 种基金Reserve Talents for Yunnan Young and Middle-aged Academic and Technical Leaders,China(Grant No.2017HB010)the Academic Qinglan Project of KUST(Grant No.1407840010)the Analysis and Testing Fund of KUST(Grant No.2017M20162230010)the High-level Talents of KUST(Grant No.1411909425)。
文摘The fascinating Dirac cone in honeycomb graphene,which underlies many unique electronic properties,has inspired the vast endeavors on pursuing new two-dimensional(2D)Dirac materials.Based on the density functional theory method,a 2D material Zn3Si2 of honeycomb transition-metal silicide with intrinsic Dirac cones has been predicted.The Zn3Si2 monolayer is dynamically and thermodynamically stable under ambient conditions.Importantly,the Zn3Si2 monolayer is a room-temperature 2D Dirac material with a spin-orbit coupling energy gap of 1.2 meV,which has an intrinsic Dirac cone arising from the special hexagonal lattice structure.Hole doping leads to the spin polarization of the electron,which results in a Dirac half-metal feature with single-spin Dirac fermion.This novel stable 2D transition-metal-silicon-framework material holds promises for electronic device applications in spintronics.
基金supported by grants from the National Natural Science Foundation of China(nos.81670269,81500355,and 81500226)the Natural Science Foundation of Hunan Province(no.2019JJ40438).
文摘The present study evaluated risk factors related to persistent atrial fibrillation(AF)at discharge(AF-d)and recurrent atrial fibrillation(rAF)and all-cause death after the maze IV procedure.Two hundred nineteen patients(63 female,aged 52.5±8.8 years)with valve disease and persistent AF undergoing valve surgery and the maze IV procedure in our center between 2015 and 2016 were included.Baseline demographic and clinical data were obtained by review of medical records.The median follow-up period was 27 months(interquartile range 21-34 months)in our patient cohort.The primary end point was all-cause death.The secondary end point was AF-d or rAF.rAF is defined as AF recurrence at 3 months or later after the procedure.Twenty-eight patients(12.8%)died during follow-up.Multiple logistic regression analysis showed that thrombocytopenia,elevated serum total bilirubin level,a larger right atrium,AF-d,and rAF were independent determinants for all-cause death after the maze IV procedure after adjustment for age,sex,and clinical covariates,including New York Heart Association class III/IV disease,hypertension,and aortic regurgitation,while valvular disease duration and left atrial diameter greater than 80.5 mm were independent determinants for AF-d,and thrombocytopenia,elevated serum total bilirubin level,higher mean pulmonary artery pressure,and AF-d were independent predictors for rAF.In conclusion,thrombocytopenia,elevated serum total bilirubin level,an enlarged right atrium,AF-d,and rAF are independent predictors of all-cause death in patients undergoing the maze IV procedure.
基金the National Natural Science Foundation of China(11604105,61627827,81630046,61331001,91539127,61361160414)The National High Technology Research and Development Program of China(2015AA020901)The Science and Technology Planning Project of Guangdong Province,China(2015B020233016 and 2014B020215003).
文摘Photoacoustic imaging(PAI)breaks through the optical di®usion limit by making use of the PA e®ect.By converting incident photons into ultrasonic waves,PAI combines high contrast of optical imaging and high spatial resolution in depth tissue of ultrasound imaging in a single imaging modality.This imaging modality has now shown potential for molecular imaging,which enables visualization of biological processes with systemically introduced functional nanoparticles.In the current review,the potentials of di®erent optical nanoprobes as PAI contrast agents were elucidated and discussed.
基金supported by the Provincial Outstanding Youth Foundation of Jiangsu Province(BK20211529)the National Science Fund for Excellent Young Scholars(22122806)the Fundamental Research Funds for the Central Universities(JUSRP22031).
文摘The use of abundant and cheap one carbon(C1)feedstocks to produce value-added chemicals is an important approach for achieving carbon neutrality and tackling environmental problems.The conversion of C1 feedstocks to high-value chemicals is dependent on efficient C1 assimilation pathways and microbial chassis adapted for efficient incorporation.Here,we opted to summarize the natural and synthetic C1 assimilation pathways and their key factors for metabolizing C1 feedstock.Accordingly,we discussed the metabolic engineering strategies for enabling the microbial utilization of C1 feedstocks for the bioproduction of value-added chemicals.In addition,we highlighted future perspectives of C1-based biomanufacturing for achieving a low-carbon footprint for the biosynthesis of chemicals.
基金supported by the National Key R and D Program of China(2020YFA0908300)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(32021005)+1 种基金the Key Program of the National Natural Science Foundation of China(22038005)the National Natural Science Foundation of China(32070124,22008087).
文摘Microbial biorefineries to produce chemicals from renewable feedstock provides attractive advantages,including mild reaction conditions and sustainable manufacturing.However,low-efficiency biorefineries always result in an uncompetitive biological process compared to the current petrochemical process.Thus,improving microbial capacity to maximize product yield,productivity,and titer has been recognized as a central goal for bioengineers and biochemists.The knowledge of cellular biochemistry has enabled the regulation of microbial physiology to couple with chemical production.The rapid development in metabolic engineering provides diverse strategies to enhance the efficiency of chemical biosynthesis pathways.New synthetic biology tools as well as novel regulatory targets also offer the opportunity to improve biorefinery environmental adaptivity.In this review,the recent advances in building efficient biorefineries were showcased.In addition,the challenges and future perspectives of microbial host engineering for increased microbial capacity of a biorefinery were discussed.
基金supported by the National Natural Science Founda-tion of China(22122806 and 22038005)the Major Project of Natu-ral Science Foundation of Jiangsu Province(BK20212013)+1 种基金the Provin-cial Outstanding Youth Foundation of Jiangsu Province(BK20211529)the Fundamental Research Funds for the Central Universities(JUSRP22031).
文摘The increasing shortage of fossil resources and environmental pollution has renewed interest in the synthesis of value-added biochemicals from methanol.However,most of native or synthetic methylotrophs are unable to assimilate methanol at a sufficient rate to produce biochemicals.Thus,the performance of methylotrophs still needs to be optimized to meet the demands of industrial applications.In this review,we provide an in-depth discussion on the properties of natural and synthetic methylotrophs,and summarize the natural and synthetic methanol assimilation pathways.Further,we discuss metabolic engineering strategies for enabling microbial utilization of methanol for the bioproduction of value-added chemicals.Finally,we highlight the potential of microbial engineering for methanol assimilation and offer guidance for achieving a low-carbon footprint for the biosynthesis of chemicals.