Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic de...Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic design of“Trunk-Branch-Leaf”strategy is proposed to prepare the ultrathin edge-riched Zn-ene“leaves”with a thickness of~2.5 nm,adjacent Zn-ene cross-linked with each other,which are supported by copper nanoneedle“branches”on copper mesh“trunks,”named as Zn-ene/Cu-CM.The resulting superstructure enables the formation of an interconnected network and multiple channels,which can be used as an electrocatalytic CO_(2) reduction reaction(CO_(2)RR)electrode to allow a fast charge and mass transfer as well as a large electrolyte reservoir.By virtue of the distinctive structure,the obtained Zn-ene/Cu-CM electrode exhibits excellent selectivity and activity toward CO production with a maximum Faradaic efficiency of 91.3%and incredible partial current density up to 40 mA cm^(−2),outperforming most of the state-of-the-art Zn-based electrodes for CO_(2) reduction.The phenolphthalein color probe combined with in situ attenuated total reflection-infrared spectroscopy uncovered the formation of the localized pseudo-alkaline microenvironment at the interface of the Zn-ene/Cu-CM electrode.Theoretical calculations confirmed that the localized pH as the origin is responsible for the adsorption of CO_(2) at the interface and the generation of *COOH and *CO intermediates.This study offers valuable insights into developing efficient electrodes through synergistic regulation of reaction microenvironments and active sites,thereby facilitating the electrolysis of practical CO_(2) conversion.展开更多
Assume that 0<p<∞ and that B is a connected nonempty open set in R^(n),and that A^(p)(B)is the vector space of all holomorphic functions F in the tubular domains R^(n)+iB such that for any compact set K⊂B,‖ y...Assume that 0<p<∞ and that B is a connected nonempty open set in R^(n),and that A^(p)(B)is the vector space of all holomorphic functions F in the tubular domains R^(n)+iB such that for any compact set K⊂B,‖ y →‖x →F(x+iy)‖Lp(R^(n))‖ L(K)<∞,so A^(p)(B)is a Frechet space with the Heine-Borel property,its topology is induced by a complete invariant metric,is not locally bounded,and hence is not normal.Furthermore,if 1≤p≤2,then the element F of A^(p)(B)can be written as a Laplace transform of some function f∈L(R^(n)).展开更多
Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of...Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.展开更多
This study investigated the important factors that affect the operating parameters of thermally regenerative ammoniabased batteries(TRABs),including the metal electrode type,membrane type,electrode surface area,electr...This study investigated the important factors that affect the operating parameters of thermally regenerative ammoniabased batteries(TRABs),including the metal electrode type,membrane type,electrode surface area,electrode distance,electrolyte concentration,and ammonia concentration.The experimental results showed that the maximum power density of TRABs with a Cu electrode was 40.0 W·m^(2),which was considerably higher than that with Ni(0.34 W·m^(2))and Co(0.14 W·m^(2))electrodes.TRABs with an anion exchange membrane had a 28.6%higher maximum power density than those with a cation exchange membrane.An increased electrode surface resulted in an increased maximum power but a decreased maximum power density.Within a certain range,TRAB performance was enhanced with decreased electrode distance and increased electrolyte concentration.An increased ammonia concentration resulted in enhanced ammonia transfer and improved the TRAB performance.展开更多
A filtered ghost imaging(GI)protocol is proposed that enables the Rayleigh diffraction limit to be exceeded in an intensity correlation system;a super-resolution reconstructed image is achieved by low-pass filtering o...A filtered ghost imaging(GI)protocol is proposed that enables the Rayleigh diffraction limit to be exceeded in an intensity correlation system;a super-resolution reconstructed image is achieved by low-pass filtering of the measured intensities.In a lensless GI experiment performed with spatial bandpass filtering,the spatial resolution can exceed the Rayleigh diffraction bound by more than a factor of 10.The resolution depends on the bandwidth of the filter,and the relationship between the two is investigated and discussed.In combination with compressed sensing programming,not only high resolution can be maintained but also image quality can be improved,while a much lower sampling number is sufficient.展开更多
Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insuffic...Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).展开更多
We propose PortraitACG,a novel framework for user-guided portrait image editing that leverages an asymmetric conditional generative adversarial network(GAN),which supports the fine-grained editing of geometries,colors...We propose PortraitACG,a novel framework for user-guided portrait image editing that leverages an asymmetric conditional generative adversarial network(GAN),which supports the fine-grained editing of geometries,colors,lights,and shadows using a single neural network model.Existing conditional GAN-based approaches usually feed the same conditional information into generators and discriminators,which is sub-optimal because these two modules are designed for different purposes.To facilitate flexible user-guided editing,we propose a novel asymmetric conditional GAN,where the generators take the transformed conditional inputs,such as edge maps,color palettes,sliders,and masks,that can be directly edited by the user,and the discriminators take the conditional inputs in a way that can guide controllable image generation more effectively.This allows image editing operations to be performed in a simpler and more intuitive manner.For example,the user can directly use a color palette to specify the desired colors of hair,skin,eyes,lips,and background and use a slider to blend colors.Moreover,users can edit the lights and shadows by modifying their corresponding masks.展开更多
Electrochemical CO_(2) reduction(CO_(2)RR)to value-added fuels and chemicals offers a promising route toward carbon neutrality.However,developing efficient and selective catalysts for the generation of multi-carbon(C^...Electrochemical CO_(2) reduction(CO_(2)RR)to value-added fuels and chemicals offers a promising route toward carbon neutrality.However,developing efficient and selective catalysts for the generation of multi-carbon(C^(2+))products remains a significant challenge.In this work,we propose a combined density functional theory(DFT)and machine learning(ML)approach to systematically screen CuSb-based catalysts with varying surface Sb atomic fractions and non-metal dopants(O,N,S,Se,and P)on the Cu_(2)Sb(100)surface for CO_(2)RR.Approximately 200 representative adsorption configurations were randomly selected for DFT calculations,which were then used to train a predictive ML model.This model enables high-accuracy predictions of the adsorption energies of key intermediates(*CO and*H)for the remaining uncalculated configurations.By integrating the K-means clustering analysis and the optimal adsorption energy selection criteria based on the Sabatier principle,the candidate configuration with the best potential for C^(2+)product formation was identified:O-doped CuSb with a surface Sb atomic fraction of 3/12.Mechanistic studies further reveal that O doping significantly strengthens *CO adsorption while suppressing *H adsorption by modulating the electronic structure,thereby lowering the CO_(2)RR energy barrier and improving the thermodynamic selectivity toward C^(2+)products.This work not only elucidates the synergistic effect of surface Sb atomic fraction and non-metal dopants on CO_(2)RR activity,but also establishes a scalable ML prediction and screening framework,providing theoretical support and methodological pathways for the design of high-performance CuSb-based catalysts.展开更多
Developing advanced electrocatalysts to convert CO_(2) into liquid fuels such as C_(2)H_(5)OH is critical for utilizing intermittent renewable energy.The formation of C_(2)H_(5)OH,however,is generally less favored com...Developing advanced electrocatalysts to convert CO_(2) into liquid fuels such as C_(2)H_(5)OH is critical for utilizing intermittent renewable energy.The formation of C_(2)H_(5)OH,however,is generally less favored compared with the other hydrocarbon products from Cu-based electrocatalysts.In this work,an alkanethiolmodified Cu_(2)O nanowire array(OTT-Cu_(2)O) was constructed with asymmetric Cu sites consisting of paired Cu-O and Cu-S motifs to overcome previous limitations of C_(2)H_(5)OH electrosynthesis via CO_(2)RR pathway.This catalyst achieves a high Faradaic efficiency of 45 % for CO_(2)-to-C_(2)H_(5)OH conversion at 300 m A/cm^(2),representing a more than two-fold enhancement over the Cu_(2)O electrode.Mechanistic investigations reveal that the Cu-S site exhibits distinct C-binding capability that stabilizes key intermediates(^(*)OCH_(2) and ^(*)CO),in contrast to the O-affinitive Cu-O site.The asymmetric S-Cu-O configuration promotes thermodynamically favorable asymmetric C-C coupling between ^(*)CO and ^(*)OCH_(2),forming the critical CO-OCH_(2) intermediate and facilitating C_(2)H_(5)OH production,as opposed to symmetric O-Cu-O sites that mainly generate HCOOH.This work offers an effective strategy for designing multi-active-site catalysts toward highly selective CO_(2) reduction to C_(2)H_(5)OH and provides fundamental insight into the reaction mechanism.展开更多
Background： Accumulating studies on computational fluid dynamics （CFD） support the involvement of hemodynamic factors in artery stenosis. Based on a patient-specific CFD model, the present study aimed to investigat...Background： Accumulating studies on computational fluid dynamics （CFD） support the involvement of hemodynamic factors in artery stenosis. Based on a patient-specific CFD model, the present study aimed to investigate the hemodynamic characteristics of transplant renal artery stenosis （TRAS） and its alteration after stent treatment. Methods： Computed tomography angiography （CTA） data of kidney transplant recipients in a single transplant center from April 2013 to November 2014 were reviewed. The three-dimensional geometry of transplant renal artery （TRA） was reconstructed from the qualified CTA images and categorized into three groups： the normal, stenotic, and stented groups. Hemodynamic parameters including pressure distribution, velocity, wall shear stress （WSS）, and mass flow rate （MFR） were extracted. The data of hemodynamic parameters were expressed as median （interquartile range）, and Mann-Whitney U-test was used for analysis. Results： Totally, 6 normal, 12 stenotic, and 6 stented TRAs were included in the analysis. TRAS presented nonuniform pressure distribution, adverse pressure gradient across stenosis throat, flow vortex, and a separation zone at downstream stenosis. Stenotic arteries had higher maximal velocity and maximal WSS （2.94 [2.14, 3.30] vs. 1.06 /0.89, 1.15] m/s, 256.5 [149.8, 349.4] vs. 41.7 [37.8, 45.3] Pa at end diastole, P - 0.001 ; 3.25 [2.67, 3.56] vs. 1.65 [ 1.18, 1.72] m/s, 281.3 [ 184.3,364.7] vs. 65.8 [61.2, 71.9] Pa at peak systole, P - 0.001 ） and lower minimal WSS and MFRs （0.07 [0.03, 0.13] vs. 0.52 [0.45, 0.67] Pa, 1.5 [1.0, 3.0] vs. 11.0 [8.0, 11.3] g/s at end diastole, P = 0.001 ; 0.08 [0.03, 0.19] vs. 0.70 [0.60, 0.81] Pa, 2.0 [1.3, 3.3] vs. 16.5 [13.0, 20.3] g/s at peak systole, P 0.001） as compared to normal arteries. Stent implantation ameliorated all the alterations of the above hemodynamic factors except low WSS. Conclusions： Hemodynamic factors were significantly changed in severe TRAS. Stent implantation can restore or ameliorate deleterious change of hemodynamic factors except low WSS at stent regions.展开更多
A piezoelectric driving method for rover vehicles is proposed in this paper. Employing this method, a tracked vehicle driven by friction forces from a frame mounted with piezoelectric elements was developed. The vehic...A piezoelectric driving method for rover vehicles is proposed in this paper. Employing this method, a tracked vehicle driven by friction forces from a frame mounted with piezoelectric elements was developed. The vehicle is designed with no driver sprocket, no idler-wheel and no supporting bogie wheels, and the vehicle thus requires no lubrication and has potential application in planetary exploration. The frame consists of a pair of piezoelectric transducers. Each transducer comprises four annular parts jointed by beams adhered with piezoelectric ceramics. The tracks are set to the outer surface of the annular parts by means of track tension. Traveling rotating waves are generated by piezoelectric transducers in the annular parts, which generate microscopic elliptical motions at the interface of the tracks. The microscopic elliptical motions from the piezoelectric transducers drive the track vehicle to move. Finite elements analysis was carried out to verify the operation principle using commercial software ANSYS. Piezoelectric transducers were fabricated, assembled and tested to validate the concepts of the proposed rover vehicle and confirm the simulation results. A prototype vehicle with mass of 0.57 kg moves at a speed of 4.3 mm/s at a driving voltage of 250 V and operating frequency of 65.53 kHz.展开更多
基金supports of the National Natural Science Foundation of China(NSFC)(52021004,52394202)key project of the Joint Fund for Innovation and Development of Chongqing Natural Science Foundation(CSTB2022NSCQ-LZX0013)+1 种基金the National Natural Science Foundation of China(NSFC)(52301232,and 52476056)the Natural Science Foundation of Chongqing Province(2024NSCQ-MSX1109).
文摘Controllable synthesis of ultrathin metallene nanosheets and rational design of their spatial arrangement in favor of electrochemical catalysis are critical for their renewable energy applications.Here,a biomimetic design of“Trunk-Branch-Leaf”strategy is proposed to prepare the ultrathin edge-riched Zn-ene“leaves”with a thickness of~2.5 nm,adjacent Zn-ene cross-linked with each other,which are supported by copper nanoneedle“branches”on copper mesh“trunks,”named as Zn-ene/Cu-CM.The resulting superstructure enables the formation of an interconnected network and multiple channels,which can be used as an electrocatalytic CO_(2) reduction reaction(CO_(2)RR)electrode to allow a fast charge and mass transfer as well as a large electrolyte reservoir.By virtue of the distinctive structure,the obtained Zn-ene/Cu-CM electrode exhibits excellent selectivity and activity toward CO production with a maximum Faradaic efficiency of 91.3%and incredible partial current density up to 40 mA cm^(−2),outperforming most of the state-of-the-art Zn-based electrodes for CO_(2) reduction.The phenolphthalein color probe combined with in situ attenuated total reflection-infrared spectroscopy uncovered the formation of the localized pseudo-alkaline microenvironment at the interface of the Zn-ene/Cu-CM electrode.Theoretical calculations confirmed that the localized pH as the origin is responsible for the adsorption of CO_(2) at the interface and the generation of *COOH and *CO intermediates.This study offers valuable insights into developing efficient electrodes through synergistic regulation of reaction microenvironments and active sites,thereby facilitating the electrolysis of practical CO_(2) conversion.
基金This work was partially supported by NSFC(11971045,12071035 and 11971063).
文摘Assume that 0<p<∞ and that B is a connected nonempty open set in R^(n),and that A^(p)(B)is the vector space of all holomorphic functions F in the tubular domains R^(n)+iB such that for any compact set K⊂B,‖ y →‖x →F(x+iy)‖Lp(R^(n))‖ L(K)<∞,so A^(p)(B)is a Frechet space with the Heine-Borel property,its topology is induced by a complete invariant metric,is not locally bounded,and hence is not normal.Furthermore,if 1≤p≤2,then the element F of A^(p)(B)can be written as a Laplace transform of some function f∈L(R^(n)).
基金supported by Innovative Research Group Project of National Natural Science Foundation of China (No. 52021004)National Natural Science Foundation of China (No. 51976018)+1 种基金Scientific Research Foundation for Returned Overseas Chinese Scholars of Chongqing, China (No. cx2021088)Research Funds of Key Laboratory of Low-grade Energy Utilization Technologies and Systems (No. LLEUTS-2018005)。
文摘Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.
基金the National Natural Science Foundation of China(No.51976018)the National Natural Science Foundation for Young Scientists of China(No.51606022)+3 种基金Natural Science Foundation of Chongqing,China(No.cstc2017jcyjAX0203)Scientific Research Foundation for Returned Overseas Chinese Scholars of Chongqing,China(No.cx2017020)the Fundamental Research Funds for the Central Universities(No.106112016CDJXY145504)Research Funds of Key Laboratory of Low-grade Energy Utilization Technologies and Systems(No.LLEUTS-2018005).
文摘This study investigated the important factors that affect the operating parameters of thermally regenerative ammoniabased batteries(TRABs),including the metal electrode type,membrane type,electrode surface area,electrode distance,electrolyte concentration,and ammonia concentration.The experimental results showed that the maximum power density of TRABs with a Cu electrode was 40.0 W·m^(2),which was considerably higher than that with Ni(0.34 W·m^(2))and Co(0.14 W·m^(2))electrodes.TRABs with an anion exchange membrane had a 28.6%higher maximum power density than those with a cation exchange membrane.An increased electrode surface resulted in an increased maximum power but a decreased maximum power density.Within a certain range,TRAB performance was enhanced with decreased electrode distance and increased electrolyte concentration.An increased ammonia concentration resulted in enhanced ammonia transfer and improved the TRAB performance.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFB0504302 and 2017YFB0503301)Defense Industrial Technology Development Program(Grant No.D040301-1)。
文摘A filtered ghost imaging(GI)protocol is proposed that enables the Rayleigh diffraction limit to be exceeded in an intensity correlation system;a super-resolution reconstructed image is achieved by low-pass filtering of the measured intensities.In a lensless GI experiment performed with spatial bandpass filtering,the spatial resolution can exceed the Rayleigh diffraction bound by more than a factor of 10.The resolution depends on the bandwidth of the filter,and the relationship between the two is investigated and discussed.In combination with compressed sensing programming,not only high resolution can be maintained but also image quality can be improved,while a much lower sampling number is sufficient.
基金support of the National Natural Science Foundation of China(Nos.52170082,51938007,21906076,and 52300081)the Natural Science Foundation of Jiangxi Province(No.20212ACB203008)。
文摘Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).
基金partly supported by the Alibaba NTU Singapore Joint Research Institute,Nanyang Technological University.
文摘We propose PortraitACG,a novel framework for user-guided portrait image editing that leverages an asymmetric conditional generative adversarial network(GAN),which supports the fine-grained editing of geometries,colors,lights,and shadows using a single neural network model.Existing conditional GAN-based approaches usually feed the same conditional information into generators and discriminators,which is sub-optimal because these two modules are designed for different purposes.To facilitate flexible user-guided editing,we propose a novel asymmetric conditional GAN,where the generators take the transformed conditional inputs,such as edge maps,color palettes,sliders,and masks,that can be directly edited by the user,and the discriminators take the conditional inputs in a way that can guide controllable image generation more effectively.This allows image editing operations to be performed in a simpler and more intuitive manner.For example,the user can directly use a color palette to specify the desired colors of hair,skin,eyes,lips,and background and use a slider to blend colors.Moreover,users can edit the lights and shadows by modifying their corresponding masks.
基金supported by the National Natural Science Foundation of China(No.No.52394202,No.52476056)State Key Laboratory of Engines,Tianjin University(K2025-10)+2 种基金the Natural Science Foundation of Chongqing(CSTB2024NSCQ-MSX0915)the China Postdoctoral Science Foundation(No.BX20240449)the Innovative Research Group Project of the National Natural Science Foundation of China(No.52021004).
文摘Electrochemical CO_(2) reduction(CO_(2)RR)to value-added fuels and chemicals offers a promising route toward carbon neutrality.However,developing efficient and selective catalysts for the generation of multi-carbon(C^(2+))products remains a significant challenge.In this work,we propose a combined density functional theory(DFT)and machine learning(ML)approach to systematically screen CuSb-based catalysts with varying surface Sb atomic fractions and non-metal dopants(O,N,S,Se,and P)on the Cu_(2)Sb(100)surface for CO_(2)RR.Approximately 200 representative adsorption configurations were randomly selected for DFT calculations,which were then used to train a predictive ML model.This model enables high-accuracy predictions of the adsorption energies of key intermediates(*CO and*H)for the remaining uncalculated configurations.By integrating the K-means clustering analysis and the optimal adsorption energy selection criteria based on the Sabatier principle,the candidate configuration with the best potential for C^(2+)product formation was identified:O-doped CuSb with a surface Sb atomic fraction of 3/12.Mechanistic studies further reveal that O doping significantly strengthens *CO adsorption while suppressing *H adsorption by modulating the electronic structure,thereby lowering the CO_(2)RR energy barrier and improving the thermodynamic selectivity toward C^(2+)products.This work not only elucidates the synergistic effect of surface Sb atomic fraction and non-metal dopants on CO_(2)RR activity,but also establishes a scalable ML prediction and screening framework,providing theoretical support and methodological pathways for the design of high-performance CuSb-based catalysts.
基金financial supports of the National Natural Science Foundation of China (NSFC,Nos.52394202,52476056,and 52301232)the Natural Science Foundation of Chongqing Province (No.2024NSCQ-MSX1109)。
文摘Developing advanced electrocatalysts to convert CO_(2) into liquid fuels such as C_(2)H_(5)OH is critical for utilizing intermittent renewable energy.The formation of C_(2)H_(5)OH,however,is generally less favored compared with the other hydrocarbon products from Cu-based electrocatalysts.In this work,an alkanethiolmodified Cu_(2)O nanowire array(OTT-Cu_(2)O) was constructed with asymmetric Cu sites consisting of paired Cu-O and Cu-S motifs to overcome previous limitations of C_(2)H_(5)OH electrosynthesis via CO_(2)RR pathway.This catalyst achieves a high Faradaic efficiency of 45 % for CO_(2)-to-C_(2)H_(5)OH conversion at 300 m A/cm^(2),representing a more than two-fold enhancement over the Cu_(2)O electrode.Mechanistic investigations reveal that the Cu-S site exhibits distinct C-binding capability that stabilizes key intermediates(^(*)OCH_(2) and ^(*)CO),in contrast to the O-affinitive Cu-O site.The asymmetric S-Cu-O configuration promotes thermodynamically favorable asymmetric C-C coupling between ^(*)CO and ^(*)OCH_(2),forming the critical CO-OCH_(2) intermediate and facilitating C_(2)H_(5)OH production,as opposed to symmetric O-Cu-O sites that mainly generate HCOOH.This work offers an effective strategy for designing multi-active-site catalysts toward highly selective CO_(2) reduction to C_(2)H_(5)OH and provides fundamental insight into the reaction mechanism.
文摘Background： Accumulating studies on computational fluid dynamics （CFD） support the involvement of hemodynamic factors in artery stenosis. Based on a patient-specific CFD model, the present study aimed to investigate the hemodynamic characteristics of transplant renal artery stenosis （TRAS） and its alteration after stent treatment. Methods： Computed tomography angiography （CTA） data of kidney transplant recipients in a single transplant center from April 2013 to November 2014 were reviewed. The three-dimensional geometry of transplant renal artery （TRA） was reconstructed from the qualified CTA images and categorized into three groups： the normal, stenotic, and stented groups. Hemodynamic parameters including pressure distribution, velocity, wall shear stress （WSS）, and mass flow rate （MFR） were extracted. The data of hemodynamic parameters were expressed as median （interquartile range）, and Mann-Whitney U-test was used for analysis. Results： Totally, 6 normal, 12 stenotic, and 6 stented TRAs were included in the analysis. TRAS presented nonuniform pressure distribution, adverse pressure gradient across stenosis throat, flow vortex, and a separation zone at downstream stenosis. Stenotic arteries had higher maximal velocity and maximal WSS （2.94 [2.14, 3.30] vs. 1.06 /0.89, 1.15] m/s, 256.5 [149.8, 349.4] vs. 41.7 [37.8, 45.3] Pa at end diastole, P - 0.001 ; 3.25 [2.67, 3.56] vs. 1.65 [ 1.18, 1.72] m/s, 281.3 [ 184.3,364.7] vs. 65.8 [61.2, 71.9] Pa at peak systole, P - 0.001 ） and lower minimal WSS and MFRs （0.07 [0.03, 0.13] vs. 0.52 [0.45, 0.67] Pa, 1.5 [1.0, 3.0] vs. 11.0 [8.0, 11.3] g/s at end diastole, P = 0.001 ; 0.08 [0.03, 0.19] vs. 0.70 [0.60, 0.81] Pa, 2.0 [1.3, 3.3] vs. 16.5 [13.0, 20.3] g/s at peak systole, P 0.001） as compared to normal arteries. Stent implantation ameliorated all the alterations of the above hemodynamic factors except low WSS. Conclusions： Hemodynamic factors were significantly changed in severe TRAS. Stent implantation can restore or ameliorate deleterious change of hemodynamic factors except low WSS at stent regions.
基金supported by the National Natural Science Foundation of China (5117702, 91023020)NFSC Guangdong Joint Fund (U0934004)Program for New Century Excellent Talents in University (NCET-10-0070)
文摘A piezoelectric driving method for rover vehicles is proposed in this paper. Employing this method, a tracked vehicle driven by friction forces from a frame mounted with piezoelectric elements was developed. The vehicle is designed with no driver sprocket, no idler-wheel and no supporting bogie wheels, and the vehicle thus requires no lubrication and has potential application in planetary exploration. The frame consists of a pair of piezoelectric transducers. Each transducer comprises four annular parts jointed by beams adhered with piezoelectric ceramics. The tracks are set to the outer surface of the annular parts by means of track tension. Traveling rotating waves are generated by piezoelectric transducers in the annular parts, which generate microscopic elliptical motions at the interface of the tracks. The microscopic elliptical motions from the piezoelectric transducers drive the track vehicle to move. Finite elements analysis was carried out to verify the operation principle using commercial software ANSYS. Piezoelectric transducers were fabricated, assembled and tested to validate the concepts of the proposed rover vehicle and confirm the simulation results. A prototype vehicle with mass of 0.57 kg moves at a speed of 4.3 mm/s at a driving voltage of 250 V and operating frequency of 65.53 kHz.
