The use of piezoelectric material sensors in smart composite structures is investigated. An experimental structure bonded with lead zirconate titanate piezoelectric ceramic(PZT) sensors is developed. These bonded sens...The use of piezoelectric material sensors in smart composite structures is investigated. An experimental structure bonded with lead zirconate titanate piezoelectric ceramic(PZT) sensors is developed. These bonded sensors are employed to monitor load variations and transient impacts in the structure. Incorporated with pattern recognition approach, PZT sensors have succeeded in detecting the onset and location of damages.展开更多
[ Objective] The aim of this study was to introduce Phosphoenolpyruvate Carboxylase (PEPCase) gene into common wheat Linyou 145. [ Method] With the material of common wheat Linyou 145, Phosphoenolpyruvate Carboxyla...[ Objective] The aim of this study was to introduce Phosphoenolpyruvate Carboxylase (PEPCase) gene into common wheat Linyou 145. [ Method] With the material of common wheat Linyou 145, Phosphoenolpyruvate Carboxylase (PEPCase) gene was introduced into wheat embryo callus by the agrobacterium-mediated transformation system, and then analyzed through successive selection with selective medium con- taing gygrornycin to detect the gene at the molecular level. [Result] The hyg-resistant plants were obtained, and GUS histochemical staining showed the leaf of resistant plants was stained dark blue. The target bands appeared in PCR analysis. [ Conclusion] Phosphoenolpyruvate Car- boxylase (PEPCase) gene has been primarily introduced into the recipient material.展开更多
Repairing effect of fly ash (FA) on damage of recycled coarse aggregate was evaluated by characteristics of pores and cracks in the vicinity of interracial transition zone (ITZ). The interracial structure between ...Repairing effect of fly ash (FA) on damage of recycled coarse aggregate was evaluated by characteristics of pores and cracks in the vicinity of interracial transition zone (ITZ). The interracial structure between the virgin aggregate and the attached old mortar was investigated and compared with ITZ of recycled aggregate concrete in the presence of FA or ultra-fine FA(UFA) by means of scanning electron microscope (SEM). Diameter and plumpness frequency distribution of pores as well as width of the old ITZ, length of contacting points and cracks density were analyzed. The SEM results reveal that the diameter of pores is decreases significantly but pores plumpness increases. A decreased ITZ width and cracks density as well as an increased bonding zone length can also been observed, which indicates that FA or UFA repairs damage of recycled coarse aggregate due to its granular effect.展开更多
A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated conditio...A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius(radius≤200 μm)spherical indenter,respectively.And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle.Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness.The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials,while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials.Moreover,the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness,respectively.The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4,respectively.展开更多
Based on the parallel bar system, combining with the synergetic method, the catastrophe theory and the acoustic emission test, a new motivated statistical damage model for quasi-brittle solid was developed. Taking con...Based on the parallel bar system, combining with the synergetic method, the catastrophe theory and the acoustic emission test, a new motivated statistical damage model for quasi-brittle solid was developed. Taking concrete for instances, the rationality and the flexibility of this model and its parameters-determining method were identified by the comparative analyses between theoretical and experimental curves. The results show that the model can simulate the whole damage and fracture process in the fracture process zone of material when the materials arc exposed to quasi-static uniaxial tensile traction. The influence of the mesoscopic damage mechanism on the macroscopic mechanical properties of quasi-brittle materials is summarized into two aspects, rupture damage and yield damage. The whole damage course is divided into the statistical even damage phase and the local breach phase, corresponding to the two stages described by the catastrophe theory. The two characteristic states, the peak nominal stress state and the critical state are distinguished, and the critical state plays a key role during the whole damage evolution course.展开更多
The deformation, of embankment has serious influences on neighboring structure and infrastructure. A trial embankment is reanalyzed by elastoplastic damage model coupling Blot' s consolidation theory. With the increa...The deformation, of embankment has serious influences on neighboring structure and infrastructure. A trial embankment is reanalyzed by elastoplastic damage model coupling Blot' s consolidation theory. With the increase in time of loading, the damage accumulation becomes larger. Under the centre and toe of embankment, damage becomes serious. Under the centre of embankment, vertical damage values are bigger than horizontal ones. Under the toe of embankment, horizontal damage values are bigger than vertical ones.展开更多
Purpose:The aim of this study was to investigate the effects of flui replacement by water or sports drinks on serum heat shock protein 70(HSP70) levels and DNA damage during exercise at a high ambient temperature.M...Purpose:The aim of this study was to investigate the effects of flui replacement by water or sports drinks on serum heat shock protein 70(HSP70) levels and DNA damage during exercise at a high ambient temperature.Methods:Ten male college athletes with an athletic career ranging from 6 to 11 years were recruited from Yonsei University.The subjects ran on a treadmill at 75% of heart rate reserve during 4 different trials:thermoneutral temperature at 18℃(T),high ambient temperature at 32℃ without flui replacement(H),high ambient temperature at 32℃ with water replacement(HW),and high ambient temperature at 32℃ with sports drink replacement(HS).During each condition,blood samples were collected at the pre-exercise baseline(PEB),immediately after exercise(IAE),and60 min post-exercise.Results:Skin temperature significant y increased during exercise and was significant y higher in H compared to T and HS at IAE.Meanwhile,serum HSP70 was significant y increased in all conditions at IAE compared to PEB and was higher in H compared to T at the former time point.Significant y increased lymphocyte DNA damage(DNA in the tail,tail length,tail moment) was observed in all trials at IAE compared to PEB,and attenuated DNA damage(tail moment) was observed in HS compared to H at IAE.Conclusion:Acute exercise elevates serum HSP70 and induces lymphocyte DNA damage.Fluid replacement by sports drink during exercise at high ambient temperature can attenuate HSP response and DNA damage by preventing dehydration and reducing thermal stress.展开更多
Based on the first order shear deformation theory(FSDT), the nonlinear dynamic equations involving transverse shear deformation and initial geometric imperfections were obtained by Hamilton's philosophy. Geometric...Based on the first order shear deformation theory(FSDT), the nonlinear dynamic equations involving transverse shear deformation and initial geometric imperfections were obtained by Hamilton's philosophy. Geometric deformation of the composite cylindrical shell was treated as the initial geometric imperfection in the dynamic equations, which were solved by the semi-analytical method in this paper. Stiffness reduction was employed for the damaged sub-layer, and the equivalent stiffness matrix was obtained for the delaminated area. By circumferential Fourier series expansions for shell displacements and loads and by using Galerkin technique, the nonlinear partial differential equations were transformed to ordinary differential equations which were finally solved by the finite difference method. The buckling was judged from shell responses by B-R criteria, and critical loads were then determined. The effect of the initial geometric deformation on the dynamic response and buckling of composite cylindrical shell was also discussed, as well as the effects of concomitant delamination and sub-layer matrix damages.展开更多
Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements o...Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements obtained during three point bending tests on Nestos marble under laboratory conditions.Acoustic emission activity was monitored using piezoelectric acoustic emission sensors,and the potential for accurate prediction of rock damage based on acoustic emission data was investigated. Damage localization was determined based on acoustic emissions generated from the critically stressed region as scattered events at stresses below and close to the strength of the material.展开更多
This article presents an experimental study on the flexural performance of reinforced concrete(RC)beams with fiber reinforced cementitious composites(FRCC)and hybrid fiber reinforced cementitious composites(HFRCC)in t...This article presents an experimental study on the flexural performance of reinforced concrete(RC)beams with fiber reinforced cementitious composites(FRCC)and hybrid fiber reinforced cementitious composites(HFRCC)in the hinge portion.Beam specimens with moderate confinement were used in the study and tested under monotonic loading.Seven diverse types of FRCC including hybrid composites using fibers in different profiles and in different volumes are employed in this study.Companion specimens such as cylindrical specimens and prism specimens are also used to study the physical properties of composites employed.The moment?curvature,stiffness behavior,ductility,crack pattern and modified flexural damage ratio are the main factors considered in this study to observe the efficacy of the employed hybrid composites.The experimental outputs demonstrate the improved post yield behavior with less rate of stiffness degradation and better damage tolerance capacity than conventional technique.展开更多
This study was conducted to evaluate the effect of different distillation methods of Mentha cordifolia Opiz. essential oil on antibacterial activity. The essential oils were isolated by water and steam, hydro, ethanol...This study was conducted to evaluate the effect of different distillation methods of Mentha cordifolia Opiz. essential oil on antibacterial activity. The essential oils were isolated by water and steam, hydro, ethanol, and 3methanol: lethanol distillations. Moreover, we also compared the efficacy of these various distillations with commercial peppermint oil. Essential oils were tested in vitro against three pathogen bacteria species by sensitivity test include disc diffusion assay (DD), minimal inhibition concentration (MIC) and maximal bactericidal concentration (MBC). Escherichia coli, Staphylococcus aureus and Salmonella typhimurium were used in this investigation. The results showed that the water and steam distillation and 3methanol: lethanol under tested by DD assay was found to be effective against all the pathogenic bacteria, in which the zone of inhibition exhibited E. coil S. aureus and S. typhimurium were 9.67 ± 0.35, 11.67 ± 0.66, 18.0± 1.15 and 9.00 ± 0.05, 8.3 ± 0.35, 19.0 ± 0.00 ram, respectively. While the hydro and ethanol distillations did action to against only E. coli which the inhibition zones were 8.67 ± 0.66 and 8.67 ± 0.35 mm, respectively. However, the commercial oil was more effective against tested pathogenic bacteria than all M. cordifolia essential oil. In case of MIC and MBC assays, the results showed that all essential oil distillation methods posed antibacterial potential in which the water and steam distillation showed the lowest MIC and MBC values against E. coli, S. aureus and S. typhimurium. It is suggested that among all M. cordifolia essential oil extractions, water and steam distillation was found to be highly bactericidal as it has shown in lowest MIC and MBC values and high in growth inhibition zone diameter.展开更多
In this paper, a theoretical and numerical study on the impact of a rubber solid on the free surface of a granular plate is presented, showing a simulation of an aircraft wheel on impact with a flexible landing surfac...In this paper, a theoretical and numerical study on the impact of a rubber solid on the free surface of a granular plate is presented, showing a simulation of an aircraft wheel on impact with a flexible landing surface. This physical action, when we use a theological approach, becomes a fundamental parameter to investigate wear and tear, and consequently strength to micro and macro pavements failure. The study has developed initially from a microscopic point of view and subsequently on macroscale. The effects are strictly linked with material degradation associated with damage evolution. The problem is developed by energetic approach on an elastic-plastic element using the functional energy containing two contributions, bulk and surface. The model simulates the behaviour of flexible runway pavements during the landing phase.展开更多
文摘The use of piezoelectric material sensors in smart composite structures is investigated. An experimental structure bonded with lead zirconate titanate piezoelectric ceramic(PZT) sensors is developed. These bonded sensors are employed to monitor load variations and transient impacts in the structure. Incorporated with pattern recognition approach, PZT sensors have succeeded in detecting the onset and location of damages.
文摘[ Objective] The aim of this study was to introduce Phosphoenolpyruvate Carboxylase (PEPCase) gene into common wheat Linyou 145. [ Method] With the material of common wheat Linyou 145, Phosphoenolpyruvate Carboxylase (PEPCase) gene was introduced into wheat embryo callus by the agrobacterium-mediated transformation system, and then analyzed through successive selection with selective medium con- taing gygrornycin to detect the gene at the molecular level. [Result] The hyg-resistant plants were obtained, and GUS histochemical staining showed the leaf of resistant plants was stained dark blue. The target bands appeared in PCR analysis. [ Conclusion] Phosphoenolpyruvate Car- boxylase (PEPCase) gene has been primarily introduced into the recipient material.
基金The Scientific Research Fund of Hunan Provincial Education Department(No.06C113)
文摘Repairing effect of fly ash (FA) on damage of recycled coarse aggregate was evaluated by characteristics of pores and cracks in the vicinity of interracial transition zone (ITZ). The interracial structure between the virgin aggregate and the attached old mortar was investigated and compared with ITZ of recycled aggregate concrete in the presence of FA or ultra-fine FA(UFA) by means of scanning electron microscope (SEM). Diameter and plumpness frequency distribution of pores as well as width of the old ITZ, length of contacting points and cracks density were analyzed. The SEM results reveal that the diameter of pores is decreases significantly but pores plumpness increases. A decreased ITZ width and cracks density as well as an increased bonding zone length can also been observed, which indicates that FA or UFA repairs damage of recycled coarse aggregate due to its granular effect.
基金Project(50375156) supported by the National Natural Science Foundation of China
文摘A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius(radius≤200 μm)spherical indenter,respectively.And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle.Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness.The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials,while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials.Moreover,the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness,respectively.The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4,respectively.
基金Projects(90510018, 50679006) supported by the National Natural Science Foundation of ChinaProject(NCET-05-0413) support by the Program for New Century Excellent Talents in University
文摘Based on the parallel bar system, combining with the synergetic method, the catastrophe theory and the acoustic emission test, a new motivated statistical damage model for quasi-brittle solid was developed. Taking concrete for instances, the rationality and the flexibility of this model and its parameters-determining method were identified by the comparative analyses between theoretical and experimental curves. The results show that the model can simulate the whole damage and fracture process in the fracture process zone of material when the materials arc exposed to quasi-static uniaxial tensile traction. The influence of the mesoscopic damage mechanism on the macroscopic mechanical properties of quasi-brittle materials is summarized into two aspects, rupture damage and yield damage. The whole damage course is divided into the statistical even damage phase and the local breach phase, corresponding to the two stages described by the catastrophe theory. The two characteristic states, the peak nominal stress state and the critical state are distinguished, and the critical state plays a key role during the whole damage evolution course.
文摘The deformation, of embankment has serious influences on neighboring structure and infrastructure. A trial embankment is reanalyzed by elastoplastic damage model coupling Blot' s consolidation theory. With the increase in time of loading, the damage accumulation becomes larger. Under the centre and toe of embankment, damage becomes serious. Under the centre of embankment, vertical damage values are bigger than horizontal ones. Under the toe of embankment, horizontal damage values are bigger than vertical ones.
基金supported by the Dong-A University research fund
文摘Purpose:The aim of this study was to investigate the effects of flui replacement by water or sports drinks on serum heat shock protein 70(HSP70) levels and DNA damage during exercise at a high ambient temperature.Methods:Ten male college athletes with an athletic career ranging from 6 to 11 years were recruited from Yonsei University.The subjects ran on a treadmill at 75% of heart rate reserve during 4 different trials:thermoneutral temperature at 18℃(T),high ambient temperature at 32℃ without flui replacement(H),high ambient temperature at 32℃ with water replacement(HW),and high ambient temperature at 32℃ with sports drink replacement(HS).During each condition,blood samples were collected at the pre-exercise baseline(PEB),immediately after exercise(IAE),and60 min post-exercise.Results:Skin temperature significant y increased during exercise and was significant y higher in H compared to T and HS at IAE.Meanwhile,serum HSP70 was significant y increased in all conditions at IAE compared to PEB and was higher in H compared to T at the former time point.Significant y increased lymphocyte DNA damage(DNA in the tail,tail length,tail moment) was observed in all trials at IAE compared to PEB,and attenuated DNA damage(tail moment) was observed in HS compared to H at IAE.Conclusion:Acute exercise elevates serum HSP70 and induces lymphocyte DNA damage.Fluid replacement by sports drink during exercise at high ambient temperature can attenuate HSP response and DNA damage by preventing dehydration and reducing thermal stress.
基金The National Natural Science Foundation of China (No.10202013)
文摘Based on the first order shear deformation theory(FSDT), the nonlinear dynamic equations involving transverse shear deformation and initial geometric imperfections were obtained by Hamilton's philosophy. Geometric deformation of the composite cylindrical shell was treated as the initial geometric imperfection in the dynamic equations, which were solved by the semi-analytical method in this paper. Stiffness reduction was employed for the damaged sub-layer, and the equivalent stiffness matrix was obtained for the delaminated area. By circumferential Fourier series expansions for shell displacements and loads and by using Galerkin technique, the nonlinear partial differential equations were transformed to ordinary differential equations which were finally solved by the finite difference method. The buckling was judged from shell responses by B-R criteria, and critical loads were then determined. The effect of the initial geometric deformation on the dynamic response and buckling of composite cylindrical shell was also discussed, as well as the effects of concomitant delamination and sub-layer matrix damages.
基金supported by the THALES Program of the Ministry of Education of Greecethe European Union in the framework of the project ‘‘Integrated understanding of Seismicity,using innovative methodologies of Fracture Mechanics along with Earthquake and Non-Extensive Statistical Physics-Application to the geodynamic system of the Hellenic Arc-SEISMO FEAR HELLARC"
文摘Development of failure in brittle materials is associated with microcracks,which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission measurements obtained during three point bending tests on Nestos marble under laboratory conditions.Acoustic emission activity was monitored using piezoelectric acoustic emission sensors,and the potential for accurate prediction of rock damage based on acoustic emission data was investigated. Damage localization was determined based on acoustic emissions generated from the critically stressed region as scattered events at stresses below and close to the strength of the material.
基金support of Reliance Industries and Bakaert Industries, India for providing fiber for the experimental work
文摘This article presents an experimental study on the flexural performance of reinforced concrete(RC)beams with fiber reinforced cementitious composites(FRCC)and hybrid fiber reinforced cementitious composites(HFRCC)in the hinge portion.Beam specimens with moderate confinement were used in the study and tested under monotonic loading.Seven diverse types of FRCC including hybrid composites using fibers in different profiles and in different volumes are employed in this study.Companion specimens such as cylindrical specimens and prism specimens are also used to study the physical properties of composites employed.The moment?curvature,stiffness behavior,ductility,crack pattern and modified flexural damage ratio are the main factors considered in this study to observe the efficacy of the employed hybrid composites.The experimental outputs demonstrate the improved post yield behavior with less rate of stiffness degradation and better damage tolerance capacity than conventional technique.
文摘This study was conducted to evaluate the effect of different distillation methods of Mentha cordifolia Opiz. essential oil on antibacterial activity. The essential oils were isolated by water and steam, hydro, ethanol, and 3methanol: lethanol distillations. Moreover, we also compared the efficacy of these various distillations with commercial peppermint oil. Essential oils were tested in vitro against three pathogen bacteria species by sensitivity test include disc diffusion assay (DD), minimal inhibition concentration (MIC) and maximal bactericidal concentration (MBC). Escherichia coli, Staphylococcus aureus and Salmonella typhimurium were used in this investigation. The results showed that the water and steam distillation and 3methanol: lethanol under tested by DD assay was found to be effective against all the pathogenic bacteria, in which the zone of inhibition exhibited E. coil S. aureus and S. typhimurium were 9.67 ± 0.35, 11.67 ± 0.66, 18.0± 1.15 and 9.00 ± 0.05, 8.3 ± 0.35, 19.0 ± 0.00 ram, respectively. While the hydro and ethanol distillations did action to against only E. coli which the inhibition zones were 8.67 ± 0.66 and 8.67 ± 0.35 mm, respectively. However, the commercial oil was more effective against tested pathogenic bacteria than all M. cordifolia essential oil. In case of MIC and MBC assays, the results showed that all essential oil distillation methods posed antibacterial potential in which the water and steam distillation showed the lowest MIC and MBC values against E. coli, S. aureus and S. typhimurium. It is suggested that among all M. cordifolia essential oil extractions, water and steam distillation was found to be highly bactericidal as it has shown in lowest MIC and MBC values and high in growth inhibition zone diameter.
文摘In this paper, a theoretical and numerical study on the impact of a rubber solid on the free surface of a granular plate is presented, showing a simulation of an aircraft wheel on impact with a flexible landing surface. This physical action, when we use a theological approach, becomes a fundamental parameter to investigate wear and tear, and consequently strength to micro and macro pavements failure. The study has developed initially from a microscopic point of view and subsequently on macroscale. The effects are strictly linked with material degradation associated with damage evolution. The problem is developed by energetic approach on an elastic-plastic element using the functional energy containing two contributions, bulk and surface. The model simulates the behaviour of flexible runway pavements during the landing phase.