Spherical bubble oscillations are widely used to model cavitation phenomena in biomedical and naval hydrodynamic systems.During collapse,a sudden increase in surrounding pressure initiates the collapse of a cavitation...Spherical bubble oscillations are widely used to model cavitation phenomena in biomedical and naval hydrodynamic systems.During collapse,a sudden increase in surrounding pressure initiates the collapse of a cavitation bubble,followed by a rebound driven by the high internal gas pressure.While the ideal gas equation of state(EOS)is commonly used to describe the internal pressure and temperature of the bubble,it is limited in its capacity to capture molecular-level effects under highly compressed conditions.In the present study,we employ non-ideal EOS for the gas(the van der Waals EOS and its volume-limited case)to investigate bubble oscillations with a focus on energy redistribution.Bubble oscillation is modeled in two phases:collapse,described by the Keller−Miksis formulation,and rebound,where peak shock pressure is estimated using similitude-based relations.To assess the role of EOS in energy redistribution,we introduce a framework that quantifies energy components in the bubble−liquid system while conserving total energy,tailored to each EOS.Using this framework,we evaluate energy concentration,acoustic radiation,and shock propagation and statistically analyze their dependence on both the driving pressure and the EOS of gas.We statistically derive scaling relations of key bubble dynamics quantities,energy concentration and radiation,and shock pressure using the driving pressure ratio.This work provides a generalizable framework and set of scaling relations for predicting bubble dynamics and energy transfer,with potential applications in evaluating the impacts of cavitation phenomena in complex practical systems.展开更多
This study explores the influence of Al addition on the microstructure,texture and mechanical deformation behavior of Mg-x Al-1Zn-1Ca(x=1,2 wt.%)alloy(referred as AZX211 and AZX311,respectively).Tensile tests were per...This study explores the influence of Al addition on the microstructure,texture and mechanical deformation behavior of Mg-x Al-1Zn-1Ca(x=1,2 wt.%)alloy(referred as AZX211 and AZX311,respectively).Tensile tests were performed at room(24℃,RT)and cryogenic temperature(-150℃,CT)to probe the dislocation and twinning evolution and its consequent effect on the strength,ductility and hardening characteristics.The results revealed that AZX311 exhibited an outstanding combination of superior strength and excellent ductility at both temperatures.This unique balance of high tensile strength and consistent ductility outperforms previously documented magnesium alloys,positioning AZX311 as an ideal material for applications that demand both robust mechanical properties and reliable ductility,particularly under low-temperature conditions.The exceptional strength at cryogenic temperatures in this alloy is attributed to the synergistic effect of dislocation strengthening and boundary strengthening,where the increased barriers to dislocation movement lead to significant hardening.The presence of nano-stacking faults and greater activation of pyramidal slip,along with their interactions,result in a substantial increase in tensile strength while maintaining ductility at cryogenic temperature making it a suitable fit for cryogenic applications.展开更多
The prevalence of cardiovascular diseases(CVDs)is increasing at a rapid pace in developed countries,and CVDs are the leading cause of morbidity and mortality.Natural products and ethnomedicine have been shown to reduc...The prevalence of cardiovascular diseases(CVDs)is increasing at a rapid pace in developed countries,and CVDs are the leading cause of morbidity and mortality.Natural products and ethnomedicine have been shown to reduce the risk of CVDs.Schizonepeta(S.)tenuifolia is a medicinal plant widely used in China,Korea,and Japan and is known to exhibit anti-inflammatory,antioxidant,and immunomodulatory activities.We hypothesized that given herbal plant exhibit pharmacological activities against CVDs,we specifically explored its effects on platelet function.Platelet aggregation was evaluated using standard light transmission aggregometry.Intracellular calcium mobilization was assessed using Fura-2/AM,and granule secretion(ATP release)was measured in a luminometer.Fibrinogen binding to integrin a_(Ⅱb)β_3,was assessed using flow cytometry.Phosphorylation of mitogen-activated protein kinase(MAPK)signaling molecules and activation of the protein kinase B(Akt)was assessed using Western blot assays.S.tenuifolia,extract potently and significantly inhibited platelet aggregation,calcium mobilization,granule secretion,and fibrinogen binding to integrin a_(Ⅱb)β_3.Moreover,all extracts significantly inhibited MAPK and Akt phosphorylation.S.tenuifolia extract inhibited platelet aggregation and granule secretion,and attenuated collagen mediated GPVI downstream signaling,indicating the potential therapeutic effects of these plant extracts on the cardiovascular system and platelet function.We suggest that S.tenuifolia extract may be a potent candidate to treat platelet-related CVDs and to be used as an antiplatelet and antithrombotic agent.展开更多
Electric heaters based on functional materials and innovative designs have been developed for various applications.In this paper,we propose a soft dielectric heater(SDH)using polyvinyl chloride-gel(PVCgel)as the diele...Electric heaters based on functional materials and innovative designs have been developed for various applications.In this paper,we propose a soft dielectric heater(SDH)using polyvinyl chloride-gel(PVCgel)as the dielectric heater and hydrogel as stretchable electrodes.Under an AC voltage,the leakage current in the PVC-gel leads to continuous injection and discharge of charges,causing the polarized plasticizers and flexible PVC chains to vibrate and collide,thereby generating heat through dielectric heating.Furthermore,the SDH generates a uniform temperature distribution even under strains up to 400%.Besides,high transmittance over 86%across the visible range renders it suitable for wearable or skin-mountable heaters from an esthetic viewpoint.Its capacitor-like structure achieves a scalable design,enabling extension from a singular cell to a row/column addressable and pixelated array of heaters.The 5×5 SDH array can deliver varied thermal information and sensations while maintaining performance even when stretched.展开更多
基金supported by Institute of Information&Communications Technology Planning&Evaluation(IITP)grant funded by the Korea government(MSIT)(No.RS-2022-00155966Artificial Intelligence Convergence Innovation Human Resources Development(EwhaWomans University)).
文摘Spherical bubble oscillations are widely used to model cavitation phenomena in biomedical and naval hydrodynamic systems.During collapse,a sudden increase in surrounding pressure initiates the collapse of a cavitation bubble,followed by a rebound driven by the high internal gas pressure.While the ideal gas equation of state(EOS)is commonly used to describe the internal pressure and temperature of the bubble,it is limited in its capacity to capture molecular-level effects under highly compressed conditions.In the present study,we employ non-ideal EOS for the gas(the van der Waals EOS and its volume-limited case)to investigate bubble oscillations with a focus on energy redistribution.Bubble oscillation is modeled in two phases:collapse,described by the Keller−Miksis formulation,and rebound,where peak shock pressure is estimated using similitude-based relations.To assess the role of EOS in energy redistribution,we introduce a framework that quantifies energy components in the bubble−liquid system while conserving total energy,tailored to each EOS.Using this framework,we evaluate energy concentration,acoustic radiation,and shock propagation and statistically analyze their dependence on both the driving pressure and the EOS of gas.We statistically derive scaling relations of key bubble dynamics quantities,energy concentration and radiation,and shock pressure using the driving pressure ratio.This work provides a generalizable framework and set of scaling relations for predicting bubble dynamics and energy transfer,with potential applications in evaluating the impacts of cavitation phenomena in complex practical systems.
基金National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2020R1C1C1004434)funding grant of Korea Institute of Industrial Technology(KITECH)(No.KITECH UR-24-0008)。
文摘This study explores the influence of Al addition on the microstructure,texture and mechanical deformation behavior of Mg-x Al-1Zn-1Ca(x=1,2 wt.%)alloy(referred as AZX211 and AZX311,respectively).Tensile tests were performed at room(24℃,RT)and cryogenic temperature(-150℃,CT)to probe the dislocation and twinning evolution and its consequent effect on the strength,ductility and hardening characteristics.The results revealed that AZX311 exhibited an outstanding combination of superior strength and excellent ductility at both temperatures.This unique balance of high tensile strength and consistent ductility outperforms previously documented magnesium alloys,positioning AZX311 as an ideal material for applications that demand both robust mechanical properties and reliable ductility,particularly under low-temperature conditions.The exceptional strength at cryogenic temperatures in this alloy is attributed to the synergistic effect of dislocation strengthening and boundary strengthening,where the increased barriers to dislocation movement lead to significant hardening.The presence of nano-stacking faults and greater activation of pyramidal slip,along with their interactions,result in a substantial increase in tensile strength while maintaining ductility at cryogenic temperature making it a suitable fit for cryogenic applications.
基金supported by the National Research Foundation of Koreagrant funded by the Korean Government(MSIP,No.2015R1D1-AIA09057204)
文摘The prevalence of cardiovascular diseases(CVDs)is increasing at a rapid pace in developed countries,and CVDs are the leading cause of morbidity and mortality.Natural products and ethnomedicine have been shown to reduce the risk of CVDs.Schizonepeta(S.)tenuifolia is a medicinal plant widely used in China,Korea,and Japan and is known to exhibit anti-inflammatory,antioxidant,and immunomodulatory activities.We hypothesized that given herbal plant exhibit pharmacological activities against CVDs,we specifically explored its effects on platelet function.Platelet aggregation was evaluated using standard light transmission aggregometry.Intracellular calcium mobilization was assessed using Fura-2/AM,and granule secretion(ATP release)was measured in a luminometer.Fibrinogen binding to integrin a_(Ⅱb)β_3,was assessed using flow cytometry.Phosphorylation of mitogen-activated protein kinase(MAPK)signaling molecules and activation of the protein kinase B(Akt)was assessed using Western blot assays.S.tenuifolia,extract potently and significantly inhibited platelet aggregation,calcium mobilization,granule secretion,and fibrinogen binding to integrin a_(Ⅱb)β_3.Moreover,all extracts significantly inhibited MAPK and Akt phosphorylation.S.tenuifolia extract inhibited platelet aggregation and granule secretion,and attenuated collagen mediated GPVI downstream signaling,indicating the potential therapeutic effects of these plant extracts on the cardiovascular system and platelet function.We suggest that S.tenuifolia extract may be a potent candidate to treat platelet-related CVDs and to be used as an antiplatelet and antithrombotic agent.
基金supported by Samsung Science and Technology Foundation(No.SRFC-IT2102-04).
文摘Electric heaters based on functional materials and innovative designs have been developed for various applications.In this paper,we propose a soft dielectric heater(SDH)using polyvinyl chloride-gel(PVCgel)as the dielectric heater and hydrogel as stretchable electrodes.Under an AC voltage,the leakage current in the PVC-gel leads to continuous injection and discharge of charges,causing the polarized plasticizers and flexible PVC chains to vibrate and collide,thereby generating heat through dielectric heating.Furthermore,the SDH generates a uniform temperature distribution even under strains up to 400%.Besides,high transmittance over 86%across the visible range renders it suitable for wearable or skin-mountable heaters from an esthetic viewpoint.Its capacitor-like structure achieves a scalable design,enabling extension from a singular cell to a row/column addressable and pixelated array of heaters.The 5×5 SDH array can deliver varied thermal information and sensations while maintaining performance even when stretched.
