Sintered metals serving as thermal interface materials(TIMs)with superior thermal conductivities show the most promise in meeting the heat dissipation requirements of next-generation wide bandgap applications.Neverthe...Sintered metals serving as thermal interface materials(TIMs)with superior thermal conductivities show the most promise in meeting the heat dissipation requirements of next-generation wide bandgap applications.Nevertheless,their thermal stabilities during high-temperature service provide significant challenges.Herein,a facile approach was developed for one-step synthesis of single-phase Ag-Cu supersaturated solid-solution nanoparticle(Ag-Cu SS-NP)pastes with adjustable Cu contents(up to 37.7 at.%),and they exhibited ultrahigh resistance to oxidation and excellent sinterability.A paste composed of Ag-Cu SS-NPs was sintered in air at 250℃ for 20 min,and this resulted in a dense supersaturated structure with an impressive thermal conductivity of 157.8 W/(m K)and a room-temperature shear strength of 133.4 MPa.Microstructural analyses demonstrated that Cu had precipitated from the Ag lattice to form Cu nanoprecipitates,which refined the grain sizes and induced high-density dislocations during sintering.For the pinning effect of dislocations and grain boundaries by the Cu nanoprecipitates and coherent twins,the high-temperature(400℃)shear strength of sintered Ag-Cu SS-NP joints was significantly improved by 67%(58.6 MPa),meanwhile the shear strength after long-term aging at 200 and 300℃for 960 h were increased by 123%(140.3 MPa)and 80%(82.4 MPa)compared to those of sintered Ag NP joints,respectively.The remarkable thermal stability is far superior to traditional TIMs,so the Ag-Cu SS-NP paste exhibits excellent potential as a TIM for high-temperature power device applications.展开更多
The Finite Element Method of Lines （FEMOL） is a semi-analytic approach and takes a position between FEM and analytic methods. First, FEMOL in Fracture Mechanics is presented in detail. Then, the method is applied to...The Finite Element Method of Lines （FEMOL） is a semi-analytic approach and takes a position between FEM and analytic methods. First, FEMOL in Fracture Mechanics is presented in detail. Then, the method is applied to a set of examples such as edge-crack plate, the central-crack plate, the plate with cracks emanating from a hole under tensile or under combination loads of tensile and bending. Their dimensionless stress distribution, the stress intensify factor （SIF） and crack opening displacement （COD） are obtained, and comparison with known solutions by other methods are reported. It is found that a good accuracy is achieved by FEMOL. The method is successfully modified to remarkably increase the accuracy and reduce convergence difficulties. So it is a very useful and new tool in studying fracture mechanics problems.展开更多
Using recycled aggregate(RA)and slag instead of natural aggregate(NA)and cement can reduce greenhouse gas emissions(GHGE)and achieve effective waste recovery.In recent years,RA has been widely used to replace NA in co...Using recycled aggregate(RA)and slag instead of natural aggregate(NA)and cement can reduce greenhouse gas emissions(GHGE)and achieve effective waste recovery.In recent years,RA has been widely used to replace NA in concrete.Every year,several researchers conduct investigations on the mechanical performance and durability of recycled aggregate concrete(RAC).Due to the loose and porous material properties of RA,the mechanical properties and durability of RAC,such as strength,carbonation resistance,permeability resistance and chloride ion penetration resistance,are greatly reduced compared with natural aggregate concrete.In contrast,concrete containing slag instead of NA and cement generally improved the strength of concrete and reduced the internal porosity of materials.Herein,we discuss the effects of RA and slag on the workability,compressive strength,splitting tensile strength,ultrasonic pulse velocity(UPV)value,and elastic modulus of concrete.The relationships between the compressive strength and the splitting tensile strength,UPV value,and elastic modulus are discussed,and the optimal substitution method is proposed.In addition,various equations for calculating the compressive strength of concrete based on performance factors related to the compressive strength are summarized.展开更多
Objective:To establish a reliable and sensitive method for evaluating quality of Yiqi Jiangzhi Granules(YQJZG).Methods:Ultra performance liquid chromatography electrospray ionization tandem mass spectrometry(UPLC-ESI-...Objective:To establish a reliable and sensitive method for evaluating quality of Yiqi Jiangzhi Granules(YQJZG).Methods:Ultra performance liquid chromatography electrospray ionization tandem mass spectrometry(UPLC-ESI-MS/MS)was employed for simultaneous determination of eight marker components.Separation was performed on an AQUITY UPLC;HSS T3 column,the mobile phase consisted of acetonitrile as the organic phase and 0.1%(volume percentage)formic acid as the aqueous.Eight marker components,ginsenoside Rg1(GRg1),ginsenoside Re(GRe),ginsenoside Rb1(Gb1),typhaneoside(TEO),isorhamnetin-3-O-neohespeidoside(IN),hesperidin(HPD),aurantio-obtusin-6-O-β-D-glucoside(AG)and curcumin(CCM),were detected by multiple reaction monitoring(MRM)mode.The Chinese Pharmacopoeia(2020 edition)was regarded as the guidance document for this method validation.Results:The method showed good linearity(R^(2)≥0.9990).The relative standard deviation(RSD)values for the instrument precision,intermediate precision and repeatability were less than 2.91%,2.88%,and 3.54%,respectively.The average recovery varied from 91.08%to 103.89%,with RSD below 3.81%.Sample solutions were found to be stable within 24 h at 4℃(RSD<2.85%).Eight marker components were successfully determined from three batches of YQJZG.Conclusion:The proposed UPLC-ESI-MS/MS method was found to be simple,fast and sensitive,and can be used for the routine quality assessment of YQJZG.Simultaneously,this method may provide a new and powerful tool of quality control for other traditional Chinese medicine analogous formulae.展开更多
Inkjet-printed electronics have become a popular research topic in recent years.For common drop-on-demand(DOD)inkjet printing technology,uneven edges are a universal problem.Many factors,such as the properties of the ...Inkjet-printed electronics have become a popular research topic in recent years.For common drop-on-demand(DOD)inkjet printing technology,uneven edges are a universal problem.Many factors,such as the properties of the ink and printing parameters,influence this problem,and numerical methods are better than experimental methods for studying these influences.In this paper,a model based on the Volume of Fluid(VOF)method and user-defined files(UDFs)in Ansys F is established to simulate the formation process of deposited ink droplets.The model and UDFs include the friction effect,and the morphology of a single droplet,two fused droplets,and multiple droplets is simulated to study the influence of different factors;some results can serve as guidelines for improving pattern quality.Finally,the effect of selective treatment is also studied to understand its advantages for inkjet printing.展开更多
Background:Depression is a common clinical phenomenon in the patients with heart failure(HF).In traditional Chinese medicine(TCM),diseases in the brain and heart are thought to be correlated and interact.Naoxintong ca...Background:Depression is a common clinical phenomenon in the patients with heart failure(HF).In traditional Chinese medicine(TCM),diseases in the brain and heart are thought to be correlated and interact.Naoxintong capsules(NXT)has been used for treating cardio-cerebrovascular diseases,while its therapeutic effect on depression after HF remains unclear.Objective:The aim of the study is to evaluate the intervention effect of NXT on depression after HF.Methods:Sprague-Dawley rats were assigned into the following 5 groups:sham,model,NXT(250,1000 mg/kg),and valsartan(8mg/kg).Coronary artery occlusion was performed to induce HF and subsequent depression in rats.The cardiac function was evaluated by echocardiography,hematoxylin-eosin staining,and Masson trichrome staining.The sucrose preference test and Morris water maze test were carried out to assess the depressive behaviors in rats.The ultrastructure of hippocampal CA1 neurons was observed and the levels of corticotropin-releasing hormone in the hypothalamus,brain-derived neurotrophic factor in the cortex,and adrenocorticotropic hormone(ACTH)in the plasma were determined by enzyme-linked immunosorbent assay.The levels of dopamine,5-hydroxytryptamine,norepinephrine,andγ-aminobutyric acid in the hippocampus were measured by UPLC-QQQ-MS.Results:NXT reduced myocardial injury and pathological changes in the cardiac tissue and increased the left ventricular ejection fraction,left ventricular fractional shortening,and cardiac output.NXT increased the sugar preference rate and number of crossings and shortened the escape latency.Furthermore,the NXT treatment restored the levels of corticotropin-releasing hormone,adrenocorticotropic hormone,brain-derived neurotrophic factor,dopamine,andγ-aminobutyric acid to the baseline values.Conclusions:NXT not only demonstrates cardioprotective effect but also attenuates depression in the rats after HF.It may exert the antidepressant effect by inhibiting the hyperactivity of the hypothalamic-pituitary-adrenal axis and recovering the levels of neurotrophic factors and neurotransmitters.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52075125 and 52105331)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010591)the Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20210324124203009,JSGG20201102154600003,GXWD20231130103814001,and GXWD20220721182229001).
文摘Sintered metals serving as thermal interface materials(TIMs)with superior thermal conductivities show the most promise in meeting the heat dissipation requirements of next-generation wide bandgap applications.Nevertheless,their thermal stabilities during high-temperature service provide significant challenges.Herein,a facile approach was developed for one-step synthesis of single-phase Ag-Cu supersaturated solid-solution nanoparticle(Ag-Cu SS-NP)pastes with adjustable Cu contents(up to 37.7 at.%),and they exhibited ultrahigh resistance to oxidation and excellent sinterability.A paste composed of Ag-Cu SS-NPs was sintered in air at 250℃ for 20 min,and this resulted in a dense supersaturated structure with an impressive thermal conductivity of 157.8 W/(m K)and a room-temperature shear strength of 133.4 MPa.Microstructural analyses demonstrated that Cu had precipitated from the Ag lattice to form Cu nanoprecipitates,which refined the grain sizes and induced high-density dislocations during sintering.For the pinning effect of dislocations and grain boundaries by the Cu nanoprecipitates and coherent twins,the high-temperature(400℃)shear strength of sintered Ag-Cu SS-NP joints was significantly improved by 67%(58.6 MPa),meanwhile the shear strength after long-term aging at 200 and 300℃for 960 h were increased by 123%(140.3 MPa)and 80%(82.4 MPa)compared to those of sintered Ag NP joints,respectively.The remarkable thermal stability is far superior to traditional TIMs,so the Ag-Cu SS-NP paste exhibits excellent potential as a TIM for high-temperature power device applications.
文摘The Finite Element Method of Lines （FEMOL） is a semi-analytic approach and takes a position between FEM and analytic methods. First, FEMOL in Fracture Mechanics is presented in detail. Then, the method is applied to a set of examples such as edge-crack plate, the central-crack plate, the plate with cracks emanating from a hole under tensile or under combination loads of tensile and bending. Their dimensionless stress distribution, the stress intensify factor （SIF） and crack opening displacement （COD） are obtained, and comparison with known solutions by other methods are reported. It is found that a good accuracy is achieved by FEMOL. The method is successfully modified to remarkably increase the accuracy and reduce convergence difficulties. So it is a very useful and new tool in studying fracture mechanics problems.
基金support received from National Natural Science Foundation of China(Grant No.U2040224)Natural Science Foundation of Henan(Grant No.212300410018)Program for Innovative Research Team(in Science and Technology)in University of Henan Province of China(Grant No.20IRTSTHN009).
文摘Using recycled aggregate(RA)and slag instead of natural aggregate(NA)and cement can reduce greenhouse gas emissions(GHGE)and achieve effective waste recovery.In recent years,RA has been widely used to replace NA in concrete.Every year,several researchers conduct investigations on the mechanical performance and durability of recycled aggregate concrete(RAC).Due to the loose and porous material properties of RA,the mechanical properties and durability of RAC,such as strength,carbonation resistance,permeability resistance and chloride ion penetration resistance,are greatly reduced compared with natural aggregate concrete.In contrast,concrete containing slag instead of NA and cement generally improved the strength of concrete and reduced the internal porosity of materials.Herein,we discuss the effects of RA and slag on the workability,compressive strength,splitting tensile strength,ultrasonic pulse velocity(UPV)value,and elastic modulus of concrete.The relationships between the compressive strength and the splitting tensile strength,UPV value,and elastic modulus are discussed,and the optimal substitution method is proposed.In addition,various equations for calculating the compressive strength of concrete based on performance factors related to the compressive strength are summarized.
基金supported by the Natural Science Foundation of Beijing Municipality(No.7192117)。
文摘Objective:To establish a reliable and sensitive method for evaluating quality of Yiqi Jiangzhi Granules(YQJZG).Methods:Ultra performance liquid chromatography electrospray ionization tandem mass spectrometry(UPLC-ESI-MS/MS)was employed for simultaneous determination of eight marker components.Separation was performed on an AQUITY UPLC;HSS T3 column,the mobile phase consisted of acetonitrile as the organic phase and 0.1%(volume percentage)formic acid as the aqueous.Eight marker components,ginsenoside Rg1(GRg1),ginsenoside Re(GRe),ginsenoside Rb1(Gb1),typhaneoside(TEO),isorhamnetin-3-O-neohespeidoside(IN),hesperidin(HPD),aurantio-obtusin-6-O-β-D-glucoside(AG)and curcumin(CCM),were detected by multiple reaction monitoring(MRM)mode.The Chinese Pharmacopoeia(2020 edition)was regarded as the guidance document for this method validation.Results:The method showed good linearity(R^(2)≥0.9990).The relative standard deviation(RSD)values for the instrument precision,intermediate precision and repeatability were less than 2.91%,2.88%,and 3.54%,respectively.The average recovery varied from 91.08%to 103.89%,with RSD below 3.81%.Sample solutions were found to be stable within 24 h at 4℃(RSD<2.85%).Eight marker components were successfully determined from three batches of YQJZG.Conclusion:The proposed UPLC-ESI-MS/MS method was found to be simple,fast and sensitive,and can be used for the routine quality assessment of YQJZG.Simultaneously,this method may provide a new and powerful tool of quality control for other traditional Chinese medicine analogous formulae.
基金supported by the National Natural Science Foundation of China (No.52075125).
文摘Inkjet-printed electronics have become a popular research topic in recent years.For common drop-on-demand(DOD)inkjet printing technology,uneven edges are a universal problem.Many factors,such as the properties of the ink and printing parameters,influence this problem,and numerical methods are better than experimental methods for studying these influences.In this paper,a model based on the Volume of Fluid(VOF)method and user-defined files(UDFs)in Ansys F is established to simulate the formation process of deposited ink droplets.The model and UDFs include the friction effect,and the morphology of a single droplet,two fused droplets,and multiple droplets is simulated to study the influence of different factors;some results can serve as guidelines for improving pattern quality.Finally,the effect of selective treatment is also studied to understand its advantages for inkjet printing.
基金supported by Scientific and Technological Innovation Project of China Academy of Chinese Medical Sciences(No.CI2021B017-07,CI2021A05208,CI2021A04202)National Natural Science Foundation of China(No.81973711).
文摘Background:Depression is a common clinical phenomenon in the patients with heart failure(HF).In traditional Chinese medicine(TCM),diseases in the brain and heart are thought to be correlated and interact.Naoxintong capsules(NXT)has been used for treating cardio-cerebrovascular diseases,while its therapeutic effect on depression after HF remains unclear.Objective:The aim of the study is to evaluate the intervention effect of NXT on depression after HF.Methods:Sprague-Dawley rats were assigned into the following 5 groups:sham,model,NXT(250,1000 mg/kg),and valsartan(8mg/kg).Coronary artery occlusion was performed to induce HF and subsequent depression in rats.The cardiac function was evaluated by echocardiography,hematoxylin-eosin staining,and Masson trichrome staining.The sucrose preference test and Morris water maze test were carried out to assess the depressive behaviors in rats.The ultrastructure of hippocampal CA1 neurons was observed and the levels of corticotropin-releasing hormone in the hypothalamus,brain-derived neurotrophic factor in the cortex,and adrenocorticotropic hormone(ACTH)in the plasma were determined by enzyme-linked immunosorbent assay.The levels of dopamine,5-hydroxytryptamine,norepinephrine,andγ-aminobutyric acid in the hippocampus were measured by UPLC-QQQ-MS.Results:NXT reduced myocardial injury and pathological changes in the cardiac tissue and increased the left ventricular ejection fraction,left ventricular fractional shortening,and cardiac output.NXT increased the sugar preference rate and number of crossings and shortened the escape latency.Furthermore,the NXT treatment restored the levels of corticotropin-releasing hormone,adrenocorticotropic hormone,brain-derived neurotrophic factor,dopamine,andγ-aminobutyric acid to the baseline values.Conclusions:NXT not only demonstrates cardioprotective effect but also attenuates depression in the rats after HF.It may exert the antidepressant effect by inhibiting the hyperactivity of the hypothalamic-pituitary-adrenal axis and recovering the levels of neurotrophic factors and neurotransmitters.
