Aim:This study aims to establish an artificial intelligence model,ThyroidNet,to diagnose thyroid nodules using deep learning techniques accurately.Methods:A novel method,ThyroidNet,is introduced and evaluated based on...Aim:This study aims to establish an artificial intelligence model,ThyroidNet,to diagnose thyroid nodules using deep learning techniques accurately.Methods:A novel method,ThyroidNet,is introduced and evaluated based on deep learning for the localization and classification of thyroid nodules.First,we propose the multitask TransUnet,which combines the TransUnet encoder and decoder with multitask learning.Second,we propose the DualLoss function,tailored to the thyroid nodule localization and classification tasks.It balances the learning of the localization and classification tasks to help improve the model’s generalization ability.Third,we introduce strategies for augmenting the data.Finally,we submit a novel deep learning model,ThyroidNet,to accurately detect thyroid nodules.Results:ThyroidNet was evaluated on private datasets and was comparable to other existing methods,including U-Net and TransUnet.Experimental results show that ThyroidNet outperformed these methods in localizing and classifying thyroid nodules.It achieved improved accuracy of 3.9%and 1.5%,respectively.Conclusion:ThyroidNet significantly improves the clinical diagnosis of thyroid nodules and supports medical image analysis tasks.Future research directions include optimization of the model structure,expansion of the dataset size,reduction of computational complexity and memory requirements,and exploration of additional applications of ThyroidNet in medical image analysis.展开更多
In Unsupervised Domain Adaptation(UDA)for person re-identification(re-ID),the primary challenge is reducing the distribution discrepancy between the source and target domains.This can be achieved by implicitly or expl...In Unsupervised Domain Adaptation(UDA)for person re-identification(re-ID),the primary challenge is reducing the distribution discrepancy between the source and target domains.This can be achieved by implicitly or explicitly constructing an appropriate intermediate domain to enhance recognition capability on the target domain.Implicit construction is difficult due to the absence of intermediate state supervision,making smooth knowledge transfer from the source to the target domain a challenge.To explicitly construct the most suitable intermediate domain for the model to gradually adapt to the feature distribution changes from the source to the target domain,we propose the Minimal Transfer Cost Framework(MTCF).MTCF considers all scenarios of the intermediate domain during the transfer process,ensuring smoother and more efficient domain alignment.Our framework mainly includes threemodules:Intermediate Domain Generator(IDG),Cross-domain Feature Constraint Module(CFCM),and Residual Channel Space Module(RCSM).First,the IDG Module is introduced to generate all possible intermediate domains,ensuring a smooth transition of knowledge fromthe source to the target domain.To reduce the cross-domain feature distribution discrepancy,we propose the CFCM Module,which quantifies the difficulty of knowledge transfer and ensures the diversity of intermediate domain features and their semantic relevance,achieving alignment between the source and target domains by incorporating mutual information and maximum mean discrepancy.We also design the RCSM,which utilizes attention mechanism to enhance the model’s focus on personnel features in low-resolution images,improving the accuracy and efficiency of person re-ID.Our proposed method outperforms existing technologies in all common UDA re-ID tasks and improves the Mean Average Precision(mAP)by 2.3%in the Market to Duke task compared to the state-of-the-art(SOTA)methods.展开更多
We report the magnetotransport and thermal properties of RuAs_(2) single crystal.RuAs_(2) exhibits semiconductor behavior and localization effect.The crossover from normal state to diffusive transport in the weak loca...We report the magnetotransport and thermal properties of RuAs_(2) single crystal.RuAs_(2) exhibits semiconductor behavior and localization effect.The crossover from normal state to diffusive transport in the weak localization(WL)state and then to variable range hopping(VRH)transport in the strong localization state has been observed.The transitions can be reflected in the measurement of resistivity and Seebeck coefficient.Negative magnetoresistance(NMR)emerges with the appearance of localization effect and is gradually suppressed in high magnetic field.The temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to VRH.The measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization effect.Our findings show that RuAs_(2) is a suitable platform to study the localized state.展开更多
Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and me...Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.展开更多
Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the...Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.展开更多
Transition metal sulfides(TMSs) are promising candidates for replacing graphite anode in LIBs. However,the low conductivity and structural collapse caused by the large volume change during lithium insertion and extrac...Transition metal sulfides(TMSs) are promising candidates for replacing graphite anode in LIBs. However,the low conductivity and structural collapse caused by the large volume change during lithium insertion and extraction greatly limit its application. Herein, we report a unique design of a two-dimensional(2 D) sandwich structure of N-doped carbon@Co9 S8@graphene(N–C@Co9 S8@G) with multilayer structure. Electrochemical tests reveal that the N–C@Co9 S8@G nanosheets possess a high reversible capacity(1009 mAhg^(-1) at 0.1 Ag^(-1)), and excellent rate capability(422mAhg^(-1) at 10 Ag^(-1)) and long cycle life(853 m Ahg^(-1) at 1Ag^(-1) for 500 cycles). Experimental studies reveal that capacitive storage contributes to the high reversible capacity. The lithium storage kinetics are studied by Galvanostatic intermittent titration technique(GITT) and electrochemical impedance spectroscopy(EIS). Meanwhile, the potential of N–C@Co9 S8@G anode in a full cell using Li Co O2 as the cathode is also demonstrated, exhibiting a high reversible capacity of 300mAhg^(-1) cycles at 0.1Ag^(-1). The strategy proposed in this work paves the way to engineering high performance anodes in LIBs.展开更多
Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. T...Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.展开更多
The influences of rolling reduction and aluminum sheet initial thickness(AIT)on the thickness fluctuation of aluminum layer(TFA)of embedded aluminum?steel composite sheet produced by cold roll bonding were investigate...The influences of rolling reduction and aluminum sheet initial thickness(AIT)on the thickness fluctuation of aluminum layer(TFA)of embedded aluminum?steel composite sheet produced by cold roll bonding were investigated,the formation mechanism of TFA was analyzed and method to improve the thickness uniformity of the aluminum layer was proposed.The results showed that when the reduction increased,TFA increased gradually.When the reduction was lower than40%,AIT had negligible effect on the TFA,while TFA increased with the decrease of AIT when the reduction was higher than40%.The non-uniformities of the steel surface deformation and the interfacial bonding extent caused by the work-hardened steel surface layer,were the main reasons for the formation of TFA.Adopting an appropriate surface treatment can help to decrease the hardening extent of the steel surface for improving the deformation uniformity during cold roll bonding process,which effectively improved the aluminum thickness uniformity of the embedded aluminum/steel composite sheets.展开更多
By coupling the phase field model with the continuity equation of incompressible fluid, Navier–Stokes equation,electric field equation, and other governing equations, a multi-field coupling model for multi-bubble coa...By coupling the phase field model with the continuity equation of incompressible fluid, Navier–Stokes equation,electric field equation, and other governing equations, a multi-field coupling model for multi-bubble coalescence in a viscous fluids is established. The phase field method is used to capture the two-phase interface. The motion and coalescence of a pair of coaxial bubbles under an external uniform electric field and the effects of different electric field strengths on the interaction and coalescence of rising bubbles are studied. The results show that the uniform electric field accelerates the collision and coalescence process of double bubbles in the fluid, and increases the rising velocity of the coalesced bubble.The electric field with an intensity of E = 2 kV/mm is reduced about 2 times compared with that without electric field in coalescence time. When the electric field strength is strong(E ≥ 1 kV/mm), the coalesced bubble will rupture before it rises to the top of the calculation area, and the time of the bubble rupturing also decreases with the increase of the electric field strength. The phase field method is compared with the simulation results of Lattice Boltzmann Method(LBM), and the shape of bubble obtained by the two methods is in good agreement, which verifies the correctness of the calculation model.展开更多
Rare earth elements(REEs) can record geologic and geochemical processes. We studied two granitic regolith profiles from different climatic zones in eastern Tibetan Plateau and found that(1)∑ RREEs ranged from119.65 t...Rare earth elements(REEs) can record geologic and geochemical processes. We studied two granitic regolith profiles from different climatic zones in eastern Tibetan Plateau and found that(1)∑ RREEs ranged from119.65 to 275.33 mg/kg in profile ND and5.11–474.55 mg/kg in profile GTC, with average values of205.79 and 161 mg/kg, respectively. ∑RREEs was higher in accumulation horizon and semi-regolith;(2) Influenced by climate, the fractionation of light and heavy REEs(LREEs and HREEs) varied during weathering. The ratio of LREEs/HREEs in pedosphere was higher than semi-regolith in tropical profile;(3) A negative Eu anomaly in both profiles was the result of bedrock weathering. A positive Ce anomaly was observed in all layers of profile ND, and only in the upper 100 cm of profile GTC. This indicates that redox conditions along the regolith profile varied considerably with climate.(4) Normalized by chondrite,LREEs accumulated much more than HREEs; REE distribution curves were right-leaning with a V-type Eu anomaly in both profiles.展开更多
Effects of soft-magnetic MnZn ferrite （Mn0.5Zn0.5Fe2O4, MZF） and hard-magnetic Ba ferrite （BaO.6Fe2O3, BaM） on the structure and magnetic transport properties of [La2/3Srl/3MnO3] （LSMO）/（x） [ferrites] （ferrit...Effects of soft-magnetic MnZn ferrite （Mn0.5Zn0.5Fe2O4, MZF） and hard-magnetic Ba ferrite （BaO.6Fe2O3, BaM） on the structure and magnetic transport properties of [La2/3Srl/3MnO3] （LSMO）/（x） [ferrites] （ferrites=MZF, BaM） composites have been investigated. It was found that the inclusion of MZF phase reduces magnetization and ferromagnetic-paramagnetic transition temperature （To） of the composites. With increasing the content of the dopants, the high-temperature magnetoresistance （MR） decreases, whereas low-temperature MR increases and reaches 42% at 150 K and x=0.1. However, for the LSMO/BaM composites, magnetization and ferromagneticparamagnetic transition temperature （To） decrease firstly as x〈5%, and then increase as x〉5%. The resistivity of the composites increases by five orders of magnitude at x=1% and is out of measured range at x=5%. High magnetic field has little effect on the resistivity and magnetoresistance originate from the pinning effect of BaM for the composites with x〉5%, which may grains.展开更多
We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band...We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips’ ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials.展开更多
BACKGROUND Acute gastrointestinal bleeding(GIB)is a life-threatening medical emergency with high morbidity and mortality.Transcatheter embolization with endovascular coils under digital subtraction angiography guidanc...BACKGROUND Acute gastrointestinal bleeding(GIB)is a life-threatening medical emergency with high morbidity and mortality.Transcatheter embolization with endovascular coils under digital subtraction angiography guidance is a common and effective method for the treatment of GIB with high technical success rates.Duodenal ulcers caused by coils wiggled from the branch of the gastroduodenal artery,which is a rare complication,have not previously been reported in a patient with right intrathoracic stomach.CASE SUMMARY A 62-year-old man had undergone thoracoscopy-assisted radical resection of esophageal cancer and gastroesophageal anastomosis 3 years ago,resulting in right intrathoracic stomach.He was admitted to the hospital 15 mo ago for dizziness and suffered acute GIB during his stay.Interventional surgery was urgently performed to embolize the branch of the gastroduodenal artery with endovascular coils.After 15 mo,the patient was re-admitted with a chief complaint of melena for 2 d,esophagogastroduodenoscopy and abdominal computed tomography revealed that some endovascular coils had migrated into the duodenal bulb,leading to a deep ulcer.Bleeding was controlled after conservative treatment.Seven months later,duodenal balloon dilatation was performed to relieve the stenosis after the removal of a few coils,and the patient was safely discharged with only one coil retained in the duodenum due to difficulties in complete removal and risk of bleeding.Mild melena recurred once during the long-term follow-up.CONCLUSION Although rare,coil wiggle after interventional therapy requires careful attention,effective precautionary measures,and more secure alternative treatment methods.展开更多
基金supported by MRC,UK (MC_PC_17171)Royal Society,UK (RP202G0230)+8 种基金BHF,UK (AA/18/3/34220)Hope Foundation for Cancer Research,UK (RM60G0680)GCRF,UK (P202PF11)Sino-UK Industrial Fund,UK (RP202G0289)LIAS,UK (P202ED10,P202RE969)Data Science Enhancement Fund,UK (P202RE237)Fight for Sight,UK (24NN201)Sino-UK Education Fund,UK (OP202006)BBSRC,UK (RM32G0178B8).
文摘Aim:This study aims to establish an artificial intelligence model,ThyroidNet,to diagnose thyroid nodules using deep learning techniques accurately.Methods:A novel method,ThyroidNet,is introduced and evaluated based on deep learning for the localization and classification of thyroid nodules.First,we propose the multitask TransUnet,which combines the TransUnet encoder and decoder with multitask learning.Second,we propose the DualLoss function,tailored to the thyroid nodule localization and classification tasks.It balances the learning of the localization and classification tasks to help improve the model’s generalization ability.Third,we introduce strategies for augmenting the data.Finally,we submit a novel deep learning model,ThyroidNet,to accurately detect thyroid nodules.Results:ThyroidNet was evaluated on private datasets and was comparable to other existing methods,including U-Net and TransUnet.Experimental results show that ThyroidNet outperformed these methods in localizing and classifying thyroid nodules.It achieved improved accuracy of 3.9%and 1.5%,respectively.Conclusion:ThyroidNet significantly improves the clinical diagnosis of thyroid nodules and supports medical image analysis tasks.Future research directions include optimization of the model structure,expansion of the dataset size,reduction of computational complexity and memory requirements,and exploration of additional applications of ThyroidNet in medical image analysis.
文摘In Unsupervised Domain Adaptation(UDA)for person re-identification(re-ID),the primary challenge is reducing the distribution discrepancy between the source and target domains.This can be achieved by implicitly or explicitly constructing an appropriate intermediate domain to enhance recognition capability on the target domain.Implicit construction is difficult due to the absence of intermediate state supervision,making smooth knowledge transfer from the source to the target domain a challenge.To explicitly construct the most suitable intermediate domain for the model to gradually adapt to the feature distribution changes from the source to the target domain,we propose the Minimal Transfer Cost Framework(MTCF).MTCF considers all scenarios of the intermediate domain during the transfer process,ensuring smoother and more efficient domain alignment.Our framework mainly includes threemodules:Intermediate Domain Generator(IDG),Cross-domain Feature Constraint Module(CFCM),and Residual Channel Space Module(RCSM).First,the IDG Module is introduced to generate all possible intermediate domains,ensuring a smooth transition of knowledge fromthe source to the target domain.To reduce the cross-domain feature distribution discrepancy,we propose the CFCM Module,which quantifies the difficulty of knowledge transfer and ensures the diversity of intermediate domain features and their semantic relevance,achieving alignment between the source and target domains by incorporating mutual information and maximum mean discrepancy.We also design the RCSM,which utilizes attention mechanism to enhance the model’s focus on personnel features in low-resolution images,improving the accuracy and efficiency of person re-ID.Our proposed method outperforms existing technologies in all common UDA re-ID tasks and improves the Mean Average Precision(mAP)by 2.3%in the Market to Duke task compared to the state-of-the-art(SOTA)methods.
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2023YFA1406500 and 2019YFA0308602)the National Natural Science Foundation of China (Grant Nos.12104011,12274388,12074425,52102333,12104010,12204004,and 11874422)the Natural Science Foundation of Anhui Province (Grant Nos.2108085QA22 and 2108085MA16)。
文摘We report the magnetotransport and thermal properties of RuAs_(2) single crystal.RuAs_(2) exhibits semiconductor behavior and localization effect.The crossover from normal state to diffusive transport in the weak localization(WL)state and then to variable range hopping(VRH)transport in the strong localization state has been observed.The transitions can be reflected in the measurement of resistivity and Seebeck coefficient.Negative magnetoresistance(NMR)emerges with the appearance of localization effect and is gradually suppressed in high magnetic field.The temperature dependent phase coherence length extracted from the fittings of NMR also indicates the transition from WL to VRH.The measurement of Hall effect reveals an anomaly of temperature dependent carrier concentration caused by localization effect.Our findings show that RuAs_(2) is a suitable platform to study the localized state.
基金supported by the Joint Research Program of Hunan Provincial Natural Science Foundation(Xiangtan)of China(2016JJ5030)Hunan 2011 Collaborative Innovation Center of Chemical Engineering&Technology with Environmental Benignity and Effective Resource Utilization and General project of Hunan Provincial Education Department(17C1526)+1 种基金PhD Startup Foundation of Xiangtan University(17QDZ05)Xiangtan University undergraduate innovative experiment program(2017XJ067)~~
文摘Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFA0901500)National Nature Science Foundation of China(Grant No.21606127,Grant No.21706126)Jiangsu synergetic innovation center for advanced bio-manufacture(Grant No.XTB1802,Grant No.XTE1844).
文摘Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.
基金financially supported by the National Natural Science Foundation of China (No. 51972182 and 61971252)the Shandong Provincial Science Foundation (ZR2019BF008 and ZR2017JL021)+1 种基金the Youth Innovation Team Project of Shandong Provincial Education Department (2020KJN015)the “Distinguished Taishan Scholar” project。
文摘Transition metal sulfides(TMSs) are promising candidates for replacing graphite anode in LIBs. However,the low conductivity and structural collapse caused by the large volume change during lithium insertion and extraction greatly limit its application. Herein, we report a unique design of a two-dimensional(2 D) sandwich structure of N-doped carbon@Co9 S8@graphene(N–C@Co9 S8@G) with multilayer structure. Electrochemical tests reveal that the N–C@Co9 S8@G nanosheets possess a high reversible capacity(1009 mAhg^(-1) at 0.1 Ag^(-1)), and excellent rate capability(422mAhg^(-1) at 10 Ag^(-1)) and long cycle life(853 m Ahg^(-1) at 1Ag^(-1) for 500 cycles). Experimental studies reveal that capacitive storage contributes to the high reversible capacity. The lithium storage kinetics are studied by Galvanostatic intermittent titration technique(GITT) and electrochemical impedance spectroscopy(EIS). Meanwhile, the potential of N–C@Co9 S8@G anode in a full cell using Li Co O2 as the cathode is also demonstrated, exhibiting a high reversible capacity of 300mAhg^(-1) cycles at 0.1Ag^(-1). The strategy proposed in this work paves the way to engineering high performance anodes in LIBs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51661020,11504149,and 11364024)the Postdoctoral Science Foundation of China(Grant No.2014M560371)the Funds for Distinguished Young Scientists of Lanzhou University of Technology,China(Grant No.J201304)
文摘Based on the Cahn-Hilliard phase field model, a three-dimensional multiple-field coupling model for simulating the motion characteristics of a rising bubble in a liquid is established in a gas-liquid two-phase flow. The gas-liquid interface motion is simulated by using a phase-field method, and the effect of the electric field intensity on bubble dynamics is studied without electric field, or with vertical electric field or horizontal electric field. Through the coupling effect of electric field and flow field, the deformation of a single rising bubble and the formation of wake vortices under the action of gravity and electric field force are studied in detail. The correctness of the results is verified by mass conservation, and the influences of different electric field directions and different voltages on the movement of bubbles in liquid are considered. The results show that the ratio of the length to axis is proportional to the strength of the electric field when the air bubble is stretched into an ellipsoid along the electric field line under the action of electrostatic gravity and surface tension. In addition, the bubble rising speed is affected by the electric field, the vertical electric field accelerates the bubble rise, and the horizontal direction slows it down.
基金Project(2013AA031301)supported by National High-tech Research and Development Program of ChinaProject(51104016)supported by National Natural Science Foundation of ChinaProject(BM2014006)supported by Jiangsu Key Laboratory for Clad Materials,China
文摘The influences of rolling reduction and aluminum sheet initial thickness(AIT)on the thickness fluctuation of aluminum layer(TFA)of embedded aluminum?steel composite sheet produced by cold roll bonding were investigated,the formation mechanism of TFA was analyzed and method to improve the thickness uniformity of the aluminum layer was proposed.The results showed that when the reduction increased,TFA increased gradually.When the reduction was lower than40%,AIT had negligible effect on the TFA,while TFA increased with the decrease of AIT when the reduction was higher than40%.The non-uniformities of the steel surface deformation and the interfacial bonding extent caused by the work-hardened steel surface layer,were the main reasons for the formation of TFA.Adopting an appropriate surface treatment can help to decrease the hardening extent of the steel surface for improving the deformation uniformity during cold roll bonding process,which effectively improved the aluminum thickness uniformity of the embedded aluminum/steel composite sheets.
基金supported by the National Natural Science Foundation of China(Grant Nos.51661020,11504149,and 11364024)the Postdoctoral Science Foundation of China(Grant No.2014M560371)the Funds for Distinguished Young Scientists of Lanzhou University of Technology,China(Grant No.J201304)
文摘By coupling the phase field model with the continuity equation of incompressible fluid, Navier–Stokes equation,electric field equation, and other governing equations, a multi-field coupling model for multi-bubble coalescence in a viscous fluids is established. The phase field method is used to capture the two-phase interface. The motion and coalescence of a pair of coaxial bubbles under an external uniform electric field and the effects of different electric field strengths on the interaction and coalescence of rising bubbles are studied. The results show that the uniform electric field accelerates the collision and coalescence process of double bubbles in the fluid, and increases the rising velocity of the coalesced bubble.The electric field with an intensity of E = 2 kV/mm is reduced about 2 times compared with that without electric field in coalescence time. When the electric field strength is strong(E ≥ 1 kV/mm), the coalesced bubble will rupture before it rises to the top of the calculation area, and the time of the bubble rupturing also decreases with the increase of the electric field strength. The phase field method is compared with the simulation results of Lattice Boltzmann Method(LBM), and the shape of bubble obtained by the two methods is in good agreement, which verifies the correctness of the calculation model.
基金funded by National Natural Science Foundation of China(41210004,41603018,41673124 and2013CB956401)ministry of water resources of People’s Republic of China(201401050)
文摘Rare earth elements(REEs) can record geologic and geochemical processes. We studied two granitic regolith profiles from different climatic zones in eastern Tibetan Plateau and found that(1)∑ RREEs ranged from119.65 to 275.33 mg/kg in profile ND and5.11–474.55 mg/kg in profile GTC, with average values of205.79 and 161 mg/kg, respectively. ∑RREEs was higher in accumulation horizon and semi-regolith;(2) Influenced by climate, the fractionation of light and heavy REEs(LREEs and HREEs) varied during weathering. The ratio of LREEs/HREEs in pedosphere was higher than semi-regolith in tropical profile;(3) A negative Eu anomaly in both profiles was the result of bedrock weathering. A positive Ce anomaly was observed in all layers of profile ND, and only in the upper 100 cm of profile GTC. This indicates that redox conditions along the regolith profile varied considerably with climate.(4) Normalized by chondrite,LREEs accumulated much more than HREEs; REE distribution curves were right-leaning with a V-type Eu anomaly in both profiles.
文摘Effects of soft-magnetic MnZn ferrite （Mn0.5Zn0.5Fe2O4, MZF） and hard-magnetic Ba ferrite （BaO.6Fe2O3, BaM） on the structure and magnetic transport properties of [La2/3Srl/3MnO3] （LSMO）/（x） [ferrites] （ferrites=MZF, BaM） composites have been investigated. It was found that the inclusion of MZF phase reduces magnetization and ferromagnetic-paramagnetic transition temperature （To） of the composites. With increasing the content of the dopants, the high-temperature magnetoresistance （MR） decreases, whereas low-temperature MR increases and reaches 42% at 150 K and x=0.1. However, for the LSMO/BaM composites, magnetization and ferromagneticparamagnetic transition temperature （To） decrease firstly as x〈5%, and then increase as x〉5%. The resistivity of the composites increases by five orders of magnitude at x=1% and is out of measured range at x=5%. High magnetic field has little effect on the resistivity and magnetoresistance originate from the pinning effect of BaM for the composites with x〉5%, which may grains.
基金Project supported by the National Key R&D Program of China(Grant Nos.2017YFA0302904,2017YFA0303201,2018YFA0305602,and 2016YFA0300604)the National Natural Science Foundation of China(Grants Nos.12074002,11574372,11674331,11804379,and 11874417)+4 种基金the National Basic Research Program of China(Grant No.2015CB921303)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grants Nos.XDB07020300,XDB07020100,and XDB33030100)the Collaborative Innovation Program of Hefei Science Center,the Chinese Academy of Sciences(Grant No.2020HSCCIP002)CASHIPS Director’s Fund,China(Grant No.BJPY2019B03)the Recruitment Program for Leading Talent Team of Anhui Province,China(2019-16)。
文摘We report the tip-induced superconductivity on the topological semimetal NbSb_(2), similar to the observation on TaAs_(2) and NbAs_(2). Belonging to the same family of MPn_(2), all these materials possess similar band structures, indicating that the tip-induced superconductivity may be closely related to their topological nature and share a common mechanism. Further analysis suggests that a bulk band should play the dominant role in such local superconductivity most likely through interface coupling. In addition, the compatibility between the induced superconductivity and tips’ ferromagnetism gives an evidence for its unconventional nature. These results provide further clues to elucidate the mechanism of the tip-induced superconductivity observed in topological materials.
文摘BACKGROUND Acute gastrointestinal bleeding(GIB)is a life-threatening medical emergency with high morbidity and mortality.Transcatheter embolization with endovascular coils under digital subtraction angiography guidance is a common and effective method for the treatment of GIB with high technical success rates.Duodenal ulcers caused by coils wiggled from the branch of the gastroduodenal artery,which is a rare complication,have not previously been reported in a patient with right intrathoracic stomach.CASE SUMMARY A 62-year-old man had undergone thoracoscopy-assisted radical resection of esophageal cancer and gastroesophageal anastomosis 3 years ago,resulting in right intrathoracic stomach.He was admitted to the hospital 15 mo ago for dizziness and suffered acute GIB during his stay.Interventional surgery was urgently performed to embolize the branch of the gastroduodenal artery with endovascular coils.After 15 mo,the patient was re-admitted with a chief complaint of melena for 2 d,esophagogastroduodenoscopy and abdominal computed tomography revealed that some endovascular coils had migrated into the duodenal bulb,leading to a deep ulcer.Bleeding was controlled after conservative treatment.Seven months later,duodenal balloon dilatation was performed to relieve the stenosis after the removal of a few coils,and the patient was safely discharged with only one coil retained in the duodenum due to difficulties in complete removal and risk of bleeding.Mild melena recurred once during the long-term follow-up.CONCLUSION Although rare,coil wiggle after interventional therapy requires careful attention,effective precautionary measures,and more secure alternative treatment methods.
