Adversarial attacks have been posing significant security concerns to intelligent systems,such as speaker recognition systems(SRSs).Most attacks assume the neural networks in the systems are known beforehand,while bla...Adversarial attacks have been posing significant security concerns to intelligent systems,such as speaker recognition systems(SRSs).Most attacks assume the neural networks in the systems are known beforehand,while black-box attacks are proposed without such information to meet practical situations.Existing black-box attacks improve trans-ferability by integrating multiple models or training on multiple datasets,but these methods are costly.Motivated by the optimisation strategy with spatial information on the perturbed paths and samples,we propose a Dual Spatial Momentum Iterative Fast Gradient Sign Method(DS-MI-FGSM)to improve the transferability of black-box at-tacks against SRSs.Specifically,DS-MI-FGSM only needs a single data and one model as the input;by extending to the data and model neighbouring spaces,it generates adver-sarial examples against the integrating models.To reduce the risk of overfitting,DS-MI-FGSM also introduces gradient masking to improve transferability.The authors conduct extensive experiments regarding the speaker recognition task,and the results demonstrate the effectiveness of their method,which can achieve up to 92%attack success rate on the victim model in black-box scenarios with only one known model.展开更多
Background: To investigate the effect of intra-abdominal volume increment(IAVI) on intra-abdominal hypertension(IAH) in the kidneys.Methods: Eight minipigs were successfully established as IAH models and were randomly...Background: To investigate the effect of intra-abdominal volume increment(IAVI) on intra-abdominal hypertension(IAH) in the kidneys.Methods: Eight minipigs were successfully established as IAH models and were randomly divided into two groups: the IAVI group and the sham-operated group. The intravesical pressure, inferior vena cava pressure and urine volume were measured before shock, 2 h after IAH, and 22 h after surgery, respectively. The following indices were measured: serum creatinine, urea nitrogen, renal cortical thickness, ratio of abdominal anteroposterior diameter/transverse diameter, renal thickness, diameter of the renal sinus and the wet/dry ratio of renal tissues.Results: The intravesical pressure(IVP) of the 8 minipig IAH models was calculated to be 21.16±4.63 mmHg. There was a significant increase in the abdominal anteroposterior diameter/transverse diameter ratio. The minipigs in the IAVI group survived during the observational period, whereas 2 minipigs died at 18 h and 20 h in the sham-operated group. Twenty-two hours after surgery, the animals in the IAVI group displayed increased urinary volume(UV) and decreased Cr and Ur and remarkable decreases of VP and IVCP. After IAH, the renal cortical thickness and the renal thickness increased significantly. The renal wet/dry ratio in the sham-operated group was higher than that in the IAVI group.Conclusion: IAVI helps to control renal dysfunction after IAH, which may be related to lowering the intra-abdominal pressure, thus alleviating renal edema and blood stasis.展开更多
“Industry 4.0” has become the future direction of manufacturing industry. To prepare for this upgrade, it is important to study the automation of semiconductor failure analysis. In this paper, the sample polishing a...“Industry 4.0” has become the future direction of manufacturing industry. To prepare for this upgrade, it is important to study the automation of semiconductor failure analysis. In this paper, the sample polishing activity was studied for upgrading to a smart polishing process. Two major issues were identified in implementing the smart polishing process: the optimization of current polishing recipes and the capability of making decisions based on live feedback. With the help of Solver add-in, the current polishing recipes were optimized. To make decisions based on live images captured during polishing, strategies were explored based on finger polishing process study. Our investigation showed that a grey scale line profile analysis on images can be used to build the vision capability of our smart polishing system, on which a decision- making capability can be developed.展开更多
As the need for energy storage devices escalates,aqueous zincion batteries(ZIBs)have risen as a promising alternative to the widely used Li-ion batteries,offering intrinsic safety,environmental compatibility,and cost ...As the need for energy storage devices escalates,aqueous zincion batteries(ZIBs)have risen as a promising alternative to the widely used Li-ion batteries,offering intrinsic safety,environmental compatibility,and cost advantages,positioning them as attractive energy storage systems for the future[1,2].However,challenges such as dendrite growth on Zn anodes,stemming from uneven electric fields on the surface and active water side reactions,compromise cycling stability and lifespan,posing significant hurdles for the practical application of ZIBs[3,4].To mitigate these issues,strategies like electrolyte optimization,artificial solid electrolyte interphase(SEI)layers,and current collector modifications have been proposed[5,6].Nevertheless,most long-cycle experiments are conducted at low current densities and deposition capacities,with high current density and capacity operations typically lasting less than 1000 h[7].展开更多
Some Chinese herbs have been used to prevent and treat diseases,and are also used as common food ingredients.These Chinese herbs are potential resource for research and development of new drugs.Leek roots is a typical...Some Chinese herbs have been used to prevent and treat diseases,and are also used as common food ingredients.These Chinese herbs are potential resource for research and development of new drugs.Leek roots is a typical medicine of food and medicine continuum.It has a long history of medicinal applications and edible food in China.In this paper,the origin,biological active components,pharmacological action and clinical application of leek roots were introduced.We hope that this review will contribute to the development of leek roots for pharmaceutical research and clinical applications,as well as related health products.展开更多
Cam-lobe radial-piston hydraulic motors are widely used in large machinery due to their excellent capability to withstand high loading at low speed.However,the line contact between the roller and cam ring generates el...Cam-lobe radial-piston hydraulic motors are widely used in large machinery due to their excellent capability to withstand high loading at low speed.However,the line contact between the roller and cam ring generates elastic deformation of the cam ring under high loading,leading to obvious speed and torque pulsations and even the detrimental crawl problem of hydraulic motors.To address this issue,we propose a deformation pre-compensated optimization design approach to compensate for the cam ring deformation in advance,thereby eliminating the influence of cam ring deformation on the hydraulic motor’s pulsation.In this approach,the design process is divided into two steps:first,the overall profile of the cam ring is optimized based on the calculated elastic deformation;second,the local profile of cam ring is further optimized until the hydraulic motor’s pulsations no longer reduce.Finally,a case study is carried out to verify the effectiveness of this approach.The result indicates the pulsation rate of a deformation pre-compensated cam ring is 40%lower than that of an uncompensated one.This study offers an easy and feasible way to design an optimized cam ring profile for low pulsation hydraulic motors.展开更多
The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction(OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeO_(x) ultra-small nanoclusters s...The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction(OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeO_(x) ultra-small nanoclusters supported on boron-doped carbon nonotubes catalyst, which achieves a 10 mA/cm^(2) anodic current density at a low overpotential of 213 mV and the Tafel slope of 52 mV/dec in 1.0 mol/L KOH, superior to the pristine NiFeO_(x)-CNTs and other state-of-the-art OER catalysts in alkaline media. A combination study(XPS, sXAS and XAFS) verifies that the local atomic structure of Ni and Fe atoms in the nanoclusters are similar to NiO and Fe_(2)O_(3), respectively, and the B atoms which are doped into the crystal lattice of CNTs leads to the optimization of Ni 3d egorbitals. Furthermore, in-situ X-ray absorption spectroscopies reveal that the high valence state of Ni atoms are served as the real active sites. This work highlights that the precise control of highly exposed multicomponent nanocluster catalysts paves a new way for designing highly efficient catalysts at the atomic scale.展开更多
The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donat...The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.展开更多
Trauma is a life-threatening "modern disease". The outcomes could only be optimized by cost-efficient and prompt trauma care, which embarks on the improvement of essential capacities and conceptual revolution in add...Trauma is a life-threatening "modern disease". The outcomes could only be optimized by cost-efficient and prompt trauma care, which embarks on the improvement of essential capacities and conceptual revolution in addition to the disruptive innovation of the trauma care system. According to experiences from the developed countries, systematic trauma care training is the cornerstone of the generalization and the improvement on the trauma care, such as the Advance Trauma Life Support (ATLS). Currently, the pre-hospital emergency medical services (EMS) has been one of the essential elements of infrastructure of health services in China, which is also fundamental to the trauma care system. Hereby, the China Trauma Care Training (CTCT) with independent intellectual property rights has been initiated and launched by the Chinese Trauma Surgeon Association to extend the up-to-date concepts and techniques in the field of trauma care as well to reinforce the generally well-accepted standardized protocols in the practices. This article reviews the current status of the trauma care system as well as the trauma care training.展开更多
Flexible piezoresistive pressure sensor with high sensitivity over a broad linearity range have been attracting tremendous attention for its applications in health monitoring,artificial intelligence,and human-machine ...Flexible piezoresistive pressure sensor with high sensitivity over a broad linearity range have been attracting tremendous attention for its applications in health monitoring,artificial intelligence,and human-machine interfaces.Herein,we report a hierarchical insitu filling porous piezoresistive sensor(HPPS)by direct ink writing(DIW)printing and curing of carbon nanofibers(CNFs)/polydimethylsiloxane(PDMS)emulsion.Hierarchical geometry significantly increases the contact area,distributes stress to multilayered lattice and internal porous structure,resulting in a broad sensing range.Moreover,unlike conventional hollow porous structure,the CNFs networks in-situ filling porous structure generates more contact sites and conductive pathways during compression,thereby achieving high sensitivity and linearity over entire sensing range.Therefore,the optimized HPPS achieves high sensitivity(4.7 kPa^(−1))and linearity(coefficient of determination,R^(2)=0.998)over a broad range(0.03-1000 kPa),together with remarkable response time and repeatability.Furthermore,the applications in diverse pressure scenarios and healthcare monitoring are demonstrated.展开更多
Herein,we report a three-dimensional porous TiO_(2)/Fe_(2)TiO_(5)/Fe_(2)O_(3)(TFF)inverse opal through in situ thermal solid reactions for photoelectrochemical water splitting.The Fe_(2)TiO_(5) interfacial layer withi...Herein,we report a three-dimensional porous TiO_(2)/Fe_(2)TiO_(5)/Fe_(2)O_(3)(TFF)inverse opal through in situ thermal solid reactions for photoelectrochemical water splitting.The Fe_(2)TiO_(5) interfacial layer within TFF acting as a bridge to tightly connect to TiO_(2) and Fe_(2)O_(3) reduces the interfacial charge transfer resistance,and suppresses the bulk carrier recombination.The optimized TFF displays a remarkable photocurrent density of 0.54mAcm^(-2) at 1.23V vs.reversible hydrogen electrode(RHE),which is 25 times higher than that of TiO_(2)/Fe_(2)O_(3)(TF)inverse opal(0.02mAcm^(-2) at 1.23V vs.RHE).The charge transfer rate in TFF inverse opal is 2-8 times higher than that of TF in the potential range of 0.7-1.5V vs.RHE.The effects of the Fe_(2)TiO_(5) interfacial layer are further revealed by X-ray absorption spectroscopy and intensity-modulated photocurrent spectroscopy.This work offers an interfacial engineering protocol to improve charge separation and transfer for efficient solar water splitting.展开更多
Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved ...Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved on a MoS_(2) Moirésuperlattice grown on the reduced graphene oxide(RGO)substrate by a hydrothermal approach.The as-synthesized bilayer MoS_(2) superlattice structure with rotating angle(ϕ=13°±1°)of two hexagonal MoS_(2) lattices,possesses outstanding ferromagnetic property and an ultra-high Curie temperature of 990 K.The X-ray absorption near-edge structure and ultraviolet photoelectron spectroscopies combined with density functional theory calculation indicate that the covalent interactions between MoS_(2) Moirésuperlattice and RGO substrate lead to the formation of interfacial Mo-S-C bonds and complete spin polarization of Mo 4d electrons near the Fermi level.This design could be generalized and may open up a possibility for tailoring the magnetism of other 2D materials.展开更多
Hybrid molecule/cluster statistical thermodynamics (HMCST) method is an efficient tool to simulate nano-scale systems under quasi-static loading at finite temperature. In this paper, a self-adaptive algorithm is dev...Hybrid molecule/cluster statistical thermodynamics (HMCST) method is an efficient tool to simulate nano-scale systems under quasi-static loading at finite temperature. In this paper, a self-adaptive algorithm is developed for this method. Explicit refinement criterion based on the gradient of slip shear deformation and a switching criterion based on generalized Einstein approximation is proposed respectively. Results show that this self-adaptive method can accurately find clusters to be refined or transferred to molecules, and efficiently refine or trans- fer the clusters. Furthermore, compared with fully atomistic simulation, the high computational efficiency of the self-adaptive method appears very attractive.展开更多
Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen conce...Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen concentration,which causes difficulties in operation and maintenance.In this study,the temperature and oxygen concentration distribution of DSWI were characterized using different air flow rates and bottom ash volumes.The results showed that the adjustment of air flow has no significant influence on the heating process of the DSWI,while the retention of bottom ash did affect the temperature and oxygen concentration fields in the furnace.When the air flow rate was increased without the retention of bottom ash,99%of the furnace volume temperature was observed between 780℃ and 800℃.However,once the bottom ash was retained,the whole furnace temperature was steadily maintained between 800℃ and 850℃.When the air flow rate was increased without bottom ash,the highest furnace volume percentage of oxygen concentrations higher than 3%maxed out at 11%volume,while it could reach 100%when bottom ash remained.The distribution of the temperature and oxygen concentration in the DSWI characterized by this research provides strong support for the operation and management of such systems.展开更多
The controlled generation of reactive oxygen species(ROS)to selectively epoxidize styrene is a grand challenge.Herein,cyano-group-modified carbon nitrides(CNCY_(x) and CN-T_(y))are prepared,and the catalysts show bett...The controlled generation of reactive oxygen species(ROS)to selectively epoxidize styrene is a grand challenge.Herein,cyano-group-modified carbon nitrides(CNCY_(x) and CN-T_(y))are prepared,and the catalysts show better performance in regulating ROS and producing styrene oxide than the cyano-free sample.The in situ diffuse reflectance infrared and density functional theory calculation results reveal that the cyano group acts as the adsorption and activation site of oxygen.X-ray photoelectron spectroscopy and NMR spectrum results confirm that the cyano group bonds with the intact heptazine ring.This unique structure could inhibit H_(2)O_(2) and,OH formation,resulting in high selectivity of styrene oxide.Furthermore,high catalytic activity is still achieved when the system scales up to 2.7 L with 100 g styrene under solar light irradiation.The strategy of cyano group modification gives a new insight into regulating spatial configuration for tuning the utilization of oxygen-active species and shows potential applications in industry.展开更多
Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnet...Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.展开更多
Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel clo...Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel cloth(SC) modified with carbon nanoparticles of Chinese ink(Cl) using polypyrrole(PPy)as a building block(PPy/Cl/SC).After modification,PPy/Cl/SC showed a 30% shorten in start-up time(36.4 ± 3.3 h vs.52.3± 1.8 h),33% increase in the maximum current(12.4 ± 1.4 mA vs.9.3± 0.95 mA),and2.3 times higher in the maximum power density of MFC(61.9 mW/m^(2) vs.27.3 mW/m^(2)),compared to Ppy/SC.Experimental results revealed that carbon nanoparticles were able to cover SC uniformly,owing to excellent dispersibility of carbon nanoparticles in Cl.The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm^(2).This enhanced electron transfer between the electrode and bacteria.Further,embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents,which were bene ficial to bacteria adhesion on electrodes.Taking adva ntage of high mechanical strength and good conductivity,a large-size PPy/Cl/SC was successfully prepared(50×60 cm^(2))demonstrating a promising potential in practical applications.This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.展开更多
基金The Major Key Project of PCL,Grant/Award Number:PCL2022A03National Natural Science Foundation of China,Grant/Award Numbers:61976064,62372137Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LZ22F020007。
文摘Adversarial attacks have been posing significant security concerns to intelligent systems,such as speaker recognition systems(SRSs).Most attacks assume the neural networks in the systems are known beforehand,while black-box attacks are proposed without such information to meet practical situations.Existing black-box attacks improve trans-ferability by integrating multiple models or training on multiple datasets,but these methods are costly.Motivated by the optimisation strategy with spatial information on the perturbed paths and samples,we propose a Dual Spatial Momentum Iterative Fast Gradient Sign Method(DS-MI-FGSM)to improve the transferability of black-box at-tacks against SRSs.Specifically,DS-MI-FGSM only needs a single data and one model as the input;by extending to the data and model neighbouring spaces,it generates adver-sarial examples against the integrating models.To reduce the risk of overfitting,DS-MI-FGSM also introduces gradient masking to improve transferability.The authors conduct extensive experiments regarding the speaker recognition task,and the results demonstrate the effectiveness of their method,which can achieve up to 92%attack success rate on the victim model in black-box scenarios with only one known model.
基金support,in part,from the "Twelfth FiveYear Plan" Scientific and Technological Supporting Program of China (2012BAI11B00)Chongqing integrated demonstration project "Trauma Emergency Treatment and Rehabilitation Technology Platform"(cstc2013jcsfC10001)
文摘Background: To investigate the effect of intra-abdominal volume increment(IAVI) on intra-abdominal hypertension(IAH) in the kidneys.Methods: Eight minipigs were successfully established as IAH models and were randomly divided into two groups: the IAVI group and the sham-operated group. The intravesical pressure, inferior vena cava pressure and urine volume were measured before shock, 2 h after IAH, and 22 h after surgery, respectively. The following indices were measured: serum creatinine, urea nitrogen, renal cortical thickness, ratio of abdominal anteroposterior diameter/transverse diameter, renal thickness, diameter of the renal sinus and the wet/dry ratio of renal tissues.Results: The intravesical pressure(IVP) of the 8 minipig IAH models was calculated to be 21.16±4.63 mmHg. There was a significant increase in the abdominal anteroposterior diameter/transverse diameter ratio. The minipigs in the IAVI group survived during the observational period, whereas 2 minipigs died at 18 h and 20 h in the sham-operated group. Twenty-two hours after surgery, the animals in the IAVI group displayed increased urinary volume(UV) and decreased Cr and Ur and remarkable decreases of VP and IVCP. After IAH, the renal cortical thickness and the renal thickness increased significantly. The renal wet/dry ratio in the sham-operated group was higher than that in the IAVI group.Conclusion: IAVI helps to control renal dysfunction after IAH, which may be related to lowering the intra-abdominal pressure, thus alleviating renal edema and blood stasis.
文摘“Industry 4.0” has become the future direction of manufacturing industry. To prepare for this upgrade, it is important to study the automation of semiconductor failure analysis. In this paper, the sample polishing activity was studied for upgrading to a smart polishing process. Two major issues were identified in implementing the smart polishing process: the optimization of current polishing recipes and the capability of making decisions based on live feedback. With the help of Solver add-in, the current polishing recipes were optimized. To make decisions based on live images captured during polishing, strategies were explored based on finger polishing process study. Our investigation showed that a grey scale line profile analysis on images can be used to build the vision capability of our smart polishing system, on which a decision- making capability can be developed.
基金supported by the National Natural Science Foundation of China(22279075)Shandong Provincial Natural Science Foundation(ZR2020YQ09).
文摘As the need for energy storage devices escalates,aqueous zincion batteries(ZIBs)have risen as a promising alternative to the widely used Li-ion batteries,offering intrinsic safety,environmental compatibility,and cost advantages,positioning them as attractive energy storage systems for the future[1,2].However,challenges such as dendrite growth on Zn anodes,stemming from uneven electric fields on the surface and active water side reactions,compromise cycling stability and lifespan,posing significant hurdles for the practical application of ZIBs[3,4].To mitigate these issues,strategies like electrolyte optimization,artificial solid electrolyte interphase(SEI)layers,and current collector modifications have been proposed[5,6].Nevertheless,most long-cycle experiments are conducted at low current densities and deposition capacities,with high current density and capacity operations typically lasting less than 1000 h[7].
基金supported by grants from Key project of Natural Science Foundation of Gansu Province(No.22JR5RA407)Lanzhou Science and Technology Planning Project(No.2020-XG-33)。
文摘Some Chinese herbs have been used to prevent and treat diseases,and are also used as common food ingredients.These Chinese herbs are potential resource for research and development of new drugs.Leek roots is a typical medicine of food and medicine continuum.It has a long history of medicinal applications and edible food in China.In this paper,the origin,biological active components,pharmacological action and clinical application of leek roots were introduced.We hope that this review will contribute to the development of leek roots for pharmaceutical research and clinical applications,as well as related health products.
基金supported by the National Key R&D Program of China(No.2021YFB3400501)the National Science Foundation of China(Nos.52105070 and U21B2074)。
文摘Cam-lobe radial-piston hydraulic motors are widely used in large machinery due to their excellent capability to withstand high loading at low speed.However,the line contact between the roller and cam ring generates elastic deformation of the cam ring under high loading,leading to obvious speed and torque pulsations and even the detrimental crawl problem of hydraulic motors.To address this issue,we propose a deformation pre-compensated optimization design approach to compensate for the cam ring deformation in advance,thereby eliminating the influence of cam ring deformation on the hydraulic motor’s pulsation.In this approach,the design process is divided into two steps:first,the overall profile of the cam ring is optimized based on the calculated elastic deformation;second,the local profile of cam ring is further optimized until the hydraulic motor’s pulsations no longer reduce.Finally,a case study is carried out to verify the effectiveness of this approach.The result indicates the pulsation rate of a deformation pre-compensated cam ring is 40%lower than that of an uncompensated one.This study offers an easy and feasible way to design an optimized cam ring profile for low pulsation hydraulic motors.
基金financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243 and 12005227)excellence program of Hefei science center CAS,(Nos.2019HSC-UE002,2020HSC-UE002,2020HSCCIP013)+1 种基金the National Key Research and Development Program of China(No.2021YFA1600800)the financial support by Postdoctoral Science Foundation of China(Nos.2019M662202,2020M682041,2020TQ0316)。
文摘The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction(OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeO_(x) ultra-small nanoclusters supported on boron-doped carbon nonotubes catalyst, which achieves a 10 mA/cm^(2) anodic current density at a low overpotential of 213 mV and the Tafel slope of 52 mV/dec in 1.0 mol/L KOH, superior to the pristine NiFeO_(x)-CNTs and other state-of-the-art OER catalysts in alkaline media. A combination study(XPS, sXAS and XAFS) verifies that the local atomic structure of Ni and Fe atoms in the nanoclusters are similar to NiO and Fe_(2)O_(3), respectively, and the B atoms which are doped into the crystal lattice of CNTs leads to the optimization of Ni 3d egorbitals. Furthermore, in-situ X-ray absorption spectroscopies reveal that the high valence state of Ni atoms are served as the real active sites. This work highlights that the precise control of highly exposed multicomponent nanocluster catalysts paves a new way for designing highly efficient catalysts at the atomic scale.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,and 12005227)the Users with Excellence Program of Hefei Science Center CAS(Nos.2021HSC-UE002,2020HSCUE002,and 2019HSC-UE002)+5 种基金the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP013)the Postdoctoral Science Foundation of China(Nos.2019M662202,2020M682041,and 2020TQ0316)the Fundamental Research Funds for the Central Universities(No.WK2310000103)The support from the Ministry of Science and Technology of China(No.2017YFA0204904)is gratefully acknowledgedThe numerical calculations in this paper have been done on the supercomputing system in the Supercomputing Center of University of Science and Technology of ChinaThis work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.
文摘Trauma is a life-threatening "modern disease". The outcomes could only be optimized by cost-efficient and prompt trauma care, which embarks on the improvement of essential capacities and conceptual revolution in addition to the disruptive innovation of the trauma care system. According to experiences from the developed countries, systematic trauma care training is the cornerstone of the generalization and the improvement on the trauma care, such as the Advance Trauma Life Support (ATLS). Currently, the pre-hospital emergency medical services (EMS) has been one of the essential elements of infrastructure of health services in China, which is also fundamental to the trauma care system. Hereby, the China Trauma Care Training (CTCT) with independent intellectual property rights has been initiated and launched by the Chinese Trauma Surgeon Association to extend the up-to-date concepts and techniques in the field of trauma care as well to reinforce the generally well-accepted standardized protocols in the practices. This article reviews the current status of the trauma care system as well as the trauma care training.
基金supported by Ningbo Municipal 3315 Talent Scheme by Ningbo Science and Technology Bureau,the Zhejiang Provincial Natural Science Foundation of China (Grant LR19F010001).
文摘Flexible piezoresistive pressure sensor with high sensitivity over a broad linearity range have been attracting tremendous attention for its applications in health monitoring,artificial intelligence,and human-machine interfaces.Herein,we report a hierarchical insitu filling porous piezoresistive sensor(HPPS)by direct ink writing(DIW)printing and curing of carbon nanofibers(CNFs)/polydimethylsiloxane(PDMS)emulsion.Hierarchical geometry significantly increases the contact area,distributes stress to multilayered lattice and internal porous structure,resulting in a broad sensing range.Moreover,unlike conventional hollow porous structure,the CNFs networks in-situ filling porous structure generates more contact sites and conductive pathways during compression,thereby achieving high sensitivity and linearity over entire sensing range.Therefore,the optimized HPPS achieves high sensitivity(4.7 kPa^(−1))and linearity(coefficient of determination,R^(2)=0.998)over a broad range(0.03-1000 kPa),together with remarkable response time and repeatability.Furthermore,the applications in diverse pressure scenarios and healthcare monitoring are demonstrated.
基金supported by the National Natural Science Foundation of China(21771001 and 51872002)Anhui Provincial Natural Science Foundation(1708085ME120)+2 种基金the Program of Anhui Scientific and Technical Leaders Reserve Candidates(2018RH168)the Scholar Program for the Outstanding Innovative Talent of College Discipline(Specialty)the doctoral start-up fund and open fund for Discipline Construction,Institute of Physical Science and Information Technology,Anhui University.
文摘Herein,we report a three-dimensional porous TiO_(2)/Fe_(2)TiO_(5)/Fe_(2)O_(3)(TFF)inverse opal through in situ thermal solid reactions for photoelectrochemical water splitting.The Fe_(2)TiO_(5) interfacial layer within TFF acting as a bridge to tightly connect to TiO_(2) and Fe_(2)O_(3) reduces the interfacial charge transfer resistance,and suppresses the bulk carrier recombination.The optimized TFF displays a remarkable photocurrent density of 0.54mAcm^(-2) at 1.23V vs.reversible hydrogen electrode(RHE),which is 25 times higher than that of TiO_(2)/Fe_(2)O_(3)(TF)inverse opal(0.02mAcm^(-2) at 1.23V vs.RHE).The charge transfer rate in TFF inverse opal is 2-8 times higher than that of TF in the potential range of 0.7-1.5V vs.RHE.The effects of the Fe_(2)TiO_(5) interfacial layer are further revealed by X-ray absorption spectroscopy and intensity-modulated photocurrent spectroscopy.This work offers an interfacial engineering protocol to improve charge separation and transfer for efficient solar water splitting.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,and 12005227)Users with Excellence Program of Hefei Science Center CAS(Nos.2019HSC-UE002,2020HSC-UE002,and 2020HSC-CIP013)+1 种基金Postdoctoral Science Foundation of China(Nos.2020TQ0316,2020M682041,and 2019M662202)The authors would like to thank BSRF,SSRF and NSRL for the synchrotron beamtime.This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved on a MoS_(2) Moirésuperlattice grown on the reduced graphene oxide(RGO)substrate by a hydrothermal approach.The as-synthesized bilayer MoS_(2) superlattice structure with rotating angle(ϕ=13°±1°)of two hexagonal MoS_(2) lattices,possesses outstanding ferromagnetic property and an ultra-high Curie temperature of 990 K.The X-ray absorption near-edge structure and ultraviolet photoelectron spectroscopies combined with density functional theory calculation indicate that the covalent interactions between MoS_(2) Moirésuperlattice and RGO substrate lead to the formation of interfacial Mo-S-C bonds and complete spin polarization of Mo 4d electrons near the Fermi level.This design could be generalized and may open up a possibility for tailoring the magnetism of other 2D materials.
基金supported by the National Natural Science Foundation of China (Nos.10932011,10772181,10732090,10772012 and 11021262)the National Basic Research Program of China (No.2007CB814803)
文摘Hybrid molecule/cluster statistical thermodynamics (HMCST) method is an efficient tool to simulate nano-scale systems under quasi-static loading at finite temperature. In this paper, a self-adaptive algorithm is developed for this method. Explicit refinement criterion based on the gradient of slip shear deformation and a switching criterion based on generalized Einstein approximation is proposed respectively. Results show that this self-adaptive method can accurately find clusters to be refined or transferred to molecules, and efficiently refine or trans- fer the clusters. Furthermore, compared with fully atomistic simulation, the high computational efficiency of the self-adaptive method appears very attractive.
基金The authors would like to acknowledge the support from National Key R&D Program of China,Key Technologies Research and Development Program(2018YFD1100600).
文摘Decentralized solid-waste incinerators(DSWIs)have certain advantages for waste disposal from villages and towns.However,the incineration condition is always affected by the distribution of temperature and oxygen concentration,which causes difficulties in operation and maintenance.In this study,the temperature and oxygen concentration distribution of DSWI were characterized using different air flow rates and bottom ash volumes.The results showed that the adjustment of air flow has no significant influence on the heating process of the DSWI,while the retention of bottom ash did affect the temperature and oxygen concentration fields in the furnace.When the air flow rate was increased without the retention of bottom ash,99%of the furnace volume temperature was observed between 780℃ and 800℃.However,once the bottom ash was retained,the whole furnace temperature was steadily maintained between 800℃ and 850℃.When the air flow rate was increased without bottom ash,the highest furnace volume percentage of oxygen concentrations higher than 3%maxed out at 11%volume,while it could reach 100%when bottom ash remained.The distribution of the temperature and oxygen concentration in the DSWI characterized by this research provides strong support for the operation and management of such systems.
基金This work was supported by the National Natural Science Foundation of China(21773284)the Key Laboratory of Interface Science and Engineering in Advanced Materials,the Ministry of Education(KLISEAM201903)the Hundred Talents Program of the Chinese Academy of Sciences and Shanxi Province.
文摘The controlled generation of reactive oxygen species(ROS)to selectively epoxidize styrene is a grand challenge.Herein,cyano-group-modified carbon nitrides(CNCY_(x) and CN-T_(y))are prepared,and the catalysts show better performance in regulating ROS and producing styrene oxide than the cyano-free sample.The in situ diffuse reflectance infrared and density functional theory calculation results reveal that the cyano group acts as the adsorption and activation site of oxygen.X-ray photoelectron spectroscopy and NMR spectrum results confirm that the cyano group bonds with the intact heptazine ring.This unique structure could inhibit H_(2)O_(2) and,OH formation,resulting in high selectivity of styrene oxide.Furthermore,high catalytic activity is still achieved when the system scales up to 2.7 L with 100 g styrene under solar light irradiation.The strategy of cyano group modification gives a new insight into regulating spatial configuration for tuning the utilization of oxygen-active species and shows potential applications in industry.
基金supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,12005227,51790491,U2032150 and U1732148)the Users with Excellence Program of Hefei Science Center CAS(Nos.2019HSC-UE002,2020HSC-UE002,2020HSC-CIP013 and 2021HSC-UE002)+1 种基金the Postdoctoral Science Foundation of China(Nos.2020M682041,2020TQ0316 and 2019M662202)the National Key Research and Development Program of China(No.2019YFA0307900)。
文摘Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.
基金supported by the Zhejiang Provincial Key Research and Development Program (No.2019C03102)the China Major Science and Technology Program for Water Pollution Control and Treatment (No.2017ZX07101003)+1 种基金the National Natural Science Foundation of China (Nos.21961160742,22075245)the Ministry Department of Zhejiang Province (No.Y201534982)。
文摘Microbial fuel cells(MFCs) have various potential applications.However,anode is a main bottleneck that limits electricity production performance of MFCs.Herein,we developed a novel anode based on a stainless steel cloth(SC) modified with carbon nanoparticles of Chinese ink(Cl) using polypyrrole(PPy)as a building block(PPy/Cl/SC).After modification,PPy/Cl/SC showed a 30% shorten in start-up time(36.4 ± 3.3 h vs.52.3± 1.8 h),33% increase in the maximum current(12.4 ± 1.4 mA vs.9.3± 0.95 mA),and2.3 times higher in the maximum power density of MFC(61.9 mW/m^(2) vs.27.3 mW/m^(2)),compared to Ppy/SC.Experimental results revealed that carbon nanoparticles were able to cover SC uniformly,owing to excellent dispersibility of carbon nanoparticles in Cl.The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm^(2).This enhanced electron transfer between the electrode and bacteria.Further,embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents,which were bene ficial to bacteria adhesion on electrodes.Taking adva ntage of high mechanical strength and good conductivity,a large-size PPy/Cl/SC was successfully prepared(50×60 cm^(2))demonstrating a promising potential in practical applications.This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.