Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with ...Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.展开更多
Micro/nano hierarchical structures could endow materials with various surface functions.However,the multilayer and multiscale characteristics of micro/nano hierarchical structures bring difficulties for their one step...Micro/nano hierarchical structures could endow materials with various surface functions.However,the multilayer and multiscale characteristics of micro/nano hierarchical structures bring difficulties for their one step and controllable fabrication.Accordingly,based on tip-based fabrication techniques,this study proposed a micro-amplitude vibration-assisted scratching method by introducing a periodic backward displacement into the conventional scratching process,which enabled the synchronous creation of the microscale V-groove and nanoscale ripples,i.e.a typical micro/nano hierarchical structure.The experiments and finite element modeling were employed to explore the formation process and mechanism of the micro/nano hierarchical structures.Being different from conventional cutting,this method was mainly based on the plow mechanism,and it could accurately replicate the shape of the indenter on the material surface.The microscale V-groove was formed due to the scratching action,and the nanoscale ripple was formed due to the extrusion action of the indenter on the microscale V-groove’s surface.Furthermore,the relationships between the processing parameters and the dimensions of the micro/nano hierarchical structures were established through experiments,and optimized processing parameters were determined to achieve regular micro/nano hierarchical structures.By this method,complex patterns constructed by various micro/nano hierarchical structures were fabricated on both flat and curved surfaces,achieving diverse surface structural colors.展开更多
[Objective] North Cordyceps is as valuable as the wild Cordyceps nensis on medicinal value, nutrients, and trace element contents, which attracts lots of researchers to explore the cultivation method. In order to mas...[Objective] North Cordyceps is as valuable as the wild Cordyceps nensis on medicinal value, nutrients, and trace element contents, which attracts lots of researchers to explore the cultivation method. In order to master the best way to increase output, an experiment was conducted [Methods] To conclude the result, 100 boxes were chosen, of which 50 boxes were treated with fungiscratching in the same condition, based on comparisons of color changing and fruit body. [Results] The stroma have consistent length in good order ,but there is 1 box of scratching happened infections after operating. [Conclusion] Scratching can promote mycelium turning color better, shorter the cycle of fruiting, and prevent the phenomenon of ＂aside grass＂; and ＂no grass＂; effectively,al of this can make the North Cordyceps grow more dense and neatly.展开更多
Single crystal silicon carbide(SiC)is widely used for optoelectronics applications.Due to the anisotropic characteristics of single crystal materials,the C face and Si face of single crystal SiC have different physica...Single crystal silicon carbide(SiC)is widely used for optoelectronics applications.Due to the anisotropic characteristics of single crystal materials,the C face and Si face of single crystal SiC have different physical properties,which may fit for particular application purposes.This paper presents an investigation of the material removal and associated subsurface defects in a set of scratching tests on the C face and Si face of 4H-SiC and 6H-SiC materials using molecular dynamics simulations.The investigation reveals that the sample material deformation consists of plastic,amorphous transformations and dislocation slips that may be prone to brittle split.The results showed that the material removal at the C face is more effective with less amorphous deformation than that at the Si face.Such a phenomenon in scratching relates to the dislocations on the basal plane(0001)of the SiC crystal.Subsurface defects were reduced by applying scratching cut depths equal to integer multiples of a half molecular lattice thickness,which formed a foundation for selecting machining control parameters for the best surface quality.展开更多
To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to eval...To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to evaluate the influence of cutting fluid properties on the machinability of glass. The sodium carbonate solution of 10.5% concentration was chosen as cutting fluid. Then the critical depths in scratching experiments with and without cutting fluid were examined. Based on this, turning experiments were carried out, and the surface quality of SF6 was assessed. Compared with the process of dry cutting, the main indexes of surface roughness decrease by over 70% totally. Experimental results indicated that the machinability of glass SF6 can be improved by using the sodium carbonate solution as cutting fluid.展开更多
Pruritus is an individual unpleasant sensation of human sensory nervous system. In the physiological condition it excerts a self-protective mechanism to protect the skin against external harmful agents. Pruritoceptive...Pruritus is an individual unpleasant sensation of human sensory nervous system. In the physiological condition it excerts a self-protective mechanism to protect the skin against external harmful agents. Pruritoceptive itch is also a major symptom of skin disease and a common reason for consulting a dermatologist in clinic. It has been well known that both histamine-dependent and histamine-independent pathways mediate acute and chronic itch sensations. Previous studies have showed common neural pathways partially shared by itch and pain sensation, and significant sex differences in pain sensation. However, sex difference in itch sensation has not been given too much attention as the majority of itch studies were done in male mice or rats till now. In the present study, we compared the scratching behaviors induced by pruritogenic agents in male and female C57BL/6 mice. The results showed that both males and females exhibited scratching behaviors in response to the intradermal injection of histamine-dependent and histamine-independent pruritogenic chemicals. Moreover, the number of scratching behaviors in response to compound 4880 and chloroquine were significantly higher in females. These results suggested that sex differences occured in histamine-dependent compound 4880-induced and histamine-independent chloroquine-induced itch sensations, but not in histamine-independent SLIGRL-NH2-induced itch sensation.展开更多
A challenge in the restoration of historical buildings is strengthened in order to guarantee their durability and the evaluation of the correct identification of materials which need to be the results of consolidation...A challenge in the restoration of historical buildings is strengthened in order to guarantee their durability and the evaluation of the correct identification of materials which need to be the results of consolidation treatments which may be applied during their repair. Methods which make such a complex characterization possible are rare. This paper presents an investigation carried out at the University of Mons （Belgium） in collaboration with the technical support and control unit, restoration directorate, of the Walloon region, aiming to evaluate the effectiveness of consolidants used to strengthen stone masonry. The characterization of the materials is based on a novel semi-destructive scratching method which allows tomographic representation of the strength of the damaged and treated areas. This paper describes the experimental methodology and presents results from laboratory experiments as well as a case study.展开更多
Itch(also called pruritus)is an unpleasant somatosensation that evokes a desire or reflex to scratch in humans and other mammals[1],Itch is now considered to be a unique sensory modality that is encoded by a labeled l...Itch(also called pruritus)is an unpleasant somatosensation that evokes a desire or reflex to scratch in humans and other mammals[1],Itch is now considered to be a unique sensory modality that is encoded by a labeled line that has genetically distinguishable neurons in the peripheral and central nervous systems[1],Acute itch evokes scratching that may help to remove potentially harmful irritants from the skin,which is believed to be evolutionarily important for survival.Pathological chronic itch often occurs in patients with inflammatory skin diseases,systemic diseases,and neurological conditions.Importantly,chronic itch causes uncontrollable itch-scratch cycles that induce skin damage,affect sleep,and seriously reduce the quality of life[2].At present,effective treatment for chronic itch is still lacking,possibly due to limited understanding of the mechanism of itch information-processing in the nervous system.Therefore,elucidation of the molecular,cellular,and circuitry mechanisms of itch will eventually help to develop new effective strategies for the management of chronic itch.展开更多
In recent 2 years, the author used a three-edged needle to scratch the vesicles for treatment of herpes zoster and obtained good therapeutic results as reported in the following. General Data 21 cases were observed in...In recent 2 years, the author used a three-edged needle to scratch the vesicles for treatment of herpes zoster and obtained good therapeutic results as reported in the following. General Data 21 cases were observed in this series, including 12 males and 9 females, with ages ranging from 4 to 72 years. The shortest disease course was 1 day and the longest. 2 weeks. Clinical Manifestations There were 15 cases with groups展开更多
Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical ...Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical polishing(ECMP). These challenges arise primarily from the mechanical fragility of such dielectrics, in which the undesirable scratches are prone to produce. To mitigate this problem, a new model is proposed to predict the initiation of scratching based on the mechanical properties of passive layer and copper substrate. In order to deduce the ratio of the passive layer yield strength to the substrate yield strength and the layer thickness, the limit analysis solution of surface scratch under Berkovich indenter is used to analyze the nano-scratch experimental measurements. The modulus of the passive layer can be calculated by the nano-indentation test combined with the FEM simulation. It is found that the film modulus is about 30% of the substrate modulus. Various regimes of scratching are delineated by FEM modeling and the results are verified by experimental data.展开更多
In this study,a modeling approach based on smooth particle hydrodynamics(SPH)was implemented to simulate the nanoscale scratching process using conical tools with different negative rake angles.The implemented model e...In this study,a modeling approach based on smooth particle hydrodynamics(SPH)was implemented to simulate the nanoscale scratching process using conical tools with different negative rake angles.The implemented model enables the study of the topography of groove profiles,scratching forces,and the residual plastic strain beneath the groove.An elastoplastic material model was employed for the workpiece,and the tool–workpiece interaction was defined by a contact model adopted from the Hertz theory.An in-house Lagrangian SPH code was implemented to perform nano-scratching simulations.The SPH simulation results were compared with nanoscale scratching experimental data available in the literature.The simulation results revealed that the normal force was more dominant compared to the cutting force,in agreement with experimental results reported for a conical tip tool with a 60°negative rake angle.In addition,the simulated groove profile was in good agreement with the groove profile produced in the aforementioned experiment.The numerical simulations also showed that the normal and cutting forces increased with the increase in the scratching depth and rake angle.Although the cutting and ploughing mechanisms were noticed in nano-scratching,the ploughing mechanism was more dominant for increased negative rake angles.It was also observed that residual plastic strain exists below the groove surface,and that the plastically deformed layer thickness beneath a scratched groove is larger for more negative values of the tool rake angle and higher scratching depths.展开更多
基金supported by the National Science Foundation for Distinguished Young Scholars of China(No.52325506)the Fundamental Research Funds for the Central Universities(No.DUT22LAB501)。
文摘Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.
基金supported by the Jilin Province Key Research and Development Plan Project(20240302066GX)the National Natural Science Foundation of China(Grant No.52075221)the Fundamental Research Funds for the Central Universities(2023-JCXK-02)。
文摘Micro/nano hierarchical structures could endow materials with various surface functions.However,the multilayer and multiscale characteristics of micro/nano hierarchical structures bring difficulties for their one step and controllable fabrication.Accordingly,based on tip-based fabrication techniques,this study proposed a micro-amplitude vibration-assisted scratching method by introducing a periodic backward displacement into the conventional scratching process,which enabled the synchronous creation of the microscale V-groove and nanoscale ripples,i.e.a typical micro/nano hierarchical structure.The experiments and finite element modeling were employed to explore the formation process and mechanism of the micro/nano hierarchical structures.Being different from conventional cutting,this method was mainly based on the plow mechanism,and it could accurately replicate the shape of the indenter on the material surface.The microscale V-groove was formed due to the scratching action,and the nanoscale ripple was formed due to the extrusion action of the indenter on the microscale V-groove’s surface.Furthermore,the relationships between the processing parameters and the dimensions of the micro/nano hierarchical structures were established through experiments,and optimized processing parameters were determined to achieve regular micro/nano hierarchical structures.By this method,complex patterns constructed by various micro/nano hierarchical structures were fabricated on both flat and curved surfaces,achieving diverse surface structural colors.
文摘[Objective] North Cordyceps is as valuable as the wild Cordyceps nensis on medicinal value, nutrients, and trace element contents, which attracts lots of researchers to explore the cultivation method. In order to master the best way to increase output, an experiment was conducted [Methods] To conclude the result, 100 boxes were chosen, of which 50 boxes were treated with fungiscratching in the same condition, based on comparisons of color changing and fruit body. [Results] The stroma have consistent length in good order ,but there is 1 box of scratching happened infections after operating. [Conclusion] Scratching can promote mycelium turning color better, shorter the cycle of fruiting, and prevent the phenomenon of ＂aside grass＂; and ＂no grass＂; effectively,al of this can make the North Cordyceps grow more dense and neatly.
基金financial support from National Natural Science Foundation of China(Grant No.51835004 and 51575197)Huaqiao University International Cultivation Program for Outstanding Postgraduates and Subsidized Projec for Postgraduates’Innovative Fund in Scientific Research of Huaqiao University(No.18011080010)。
文摘Single crystal silicon carbide(SiC)is widely used for optoelectronics applications.Due to the anisotropic characteristics of single crystal materials,the C face and Si face of single crystal SiC have different physical properties,which may fit for particular application purposes.This paper presents an investigation of the material removal and associated subsurface defects in a set of scratching tests on the C face and Si face of 4H-SiC and 6H-SiC materials using molecular dynamics simulations.The investigation reveals that the sample material deformation consists of plastic,amorphous transformations and dislocation slips that may be prone to brittle split.The results showed that the material removal at the C face is more effective with less amorphous deformation than that at the Si face.Such a phenomenon in scratching relates to the dislocations on the basal plane(0001)of the SiC crystal.Subsurface defects were reduced by applying scratching cut depths equal to integer multiples of a half molecular lattice thickness,which formed a foundation for selecting machining control parameters for the best surface quality.
基金Supported by National Natural Science Foundation of China (No. 50775057)
文摘To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to evaluate the influence of cutting fluid properties on the machinability of glass. The sodium carbonate solution of 10.5% concentration was chosen as cutting fluid. Then the critical depths in scratching experiments with and without cutting fluid were examined. Based on this, turning experiments were carried out, and the surface quality of SF6 was assessed. Compared with the process of dry cutting, the main indexes of surface roughness decrease by over 70% totally. Experimental results indicated that the machinability of glass SF6 can be improved by using the sodium carbonate solution as cutting fluid.
文摘Pruritus is an individual unpleasant sensation of human sensory nervous system. In the physiological condition it excerts a self-protective mechanism to protect the skin against external harmful agents. Pruritoceptive itch is also a major symptom of skin disease and a common reason for consulting a dermatologist in clinic. It has been well known that both histamine-dependent and histamine-independent pathways mediate acute and chronic itch sensations. Previous studies have showed common neural pathways partially shared by itch and pain sensation, and significant sex differences in pain sensation. However, sex difference in itch sensation has not been given too much attention as the majority of itch studies were done in male mice or rats till now. In the present study, we compared the scratching behaviors induced by pruritogenic agents in male and female C57BL/6 mice. The results showed that both males and females exhibited scratching behaviors in response to the intradermal injection of histamine-dependent and histamine-independent pruritogenic chemicals. Moreover, the number of scratching behaviors in response to compound 4880 and chloroquine were significantly higher in females. These results suggested that sex differences occured in histamine-dependent compound 4880-induced and histamine-independent chloroquine-induced itch sensations, but not in histamine-independent SLIGRL-NH2-induced itch sensation.
文摘A challenge in the restoration of historical buildings is strengthened in order to guarantee their durability and the evaluation of the correct identification of materials which need to be the results of consolidation treatments which may be applied during their repair. Methods which make such a complex characterization possible are rare. This paper presents an investigation carried out at the University of Mons （Belgium） in collaboration with the technical support and control unit, restoration directorate, of the Walloon region, aiming to evaluate the effectiveness of consolidants used to strengthen stone masonry. The characterization of the materials is based on a novel semi-destructive scratching method which allows tomographic representation of the strength of the damaged and treated areas. This paper describes the experimental methodology and presents results from laboratory experiments as well as a case study.
基金TL was supported by grants from the National Natural Science Foundation of China(81870874,31371179,81300968)the Natural Science Foundation of Jiangsu Province,China(BK20170004 and 2015-JY-029).XL was supported by the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(KYCX17_2034).
文摘Itch(also called pruritus)is an unpleasant somatosensation that evokes a desire or reflex to scratch in humans and other mammals[1],Itch is now considered to be a unique sensory modality that is encoded by a labeled line that has genetically distinguishable neurons in the peripheral and central nervous systems[1],Acute itch evokes scratching that may help to remove potentially harmful irritants from the skin,which is believed to be evolutionarily important for survival.Pathological chronic itch often occurs in patients with inflammatory skin diseases,systemic diseases,and neurological conditions.Importantly,chronic itch causes uncontrollable itch-scratch cycles that induce skin damage,affect sleep,and seriously reduce the quality of life[2].At present,effective treatment for chronic itch is still lacking,possibly due to limited understanding of the mechanism of itch information-processing in the nervous system.Therefore,elucidation of the molecular,cellular,and circuitry mechanisms of itch will eventually help to develop new effective strategies for the management of chronic itch.
文摘In recent 2 years, the author used a three-edged needle to scratch the vesicles for treatment of herpes zoster and obtained good therapeutic results as reported in the following. General Data 21 cases were observed in this series, including 12 males and 9 females, with ages ranging from 4 to 72 years. The shortest disease course was 1 day and the longest. 2 weeks. Clinical Manifestations There were 15 cases with groups
基金Project(50975058) supported by the National Natural Science Foundation of China
文摘Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical polishing(ECMP). These challenges arise primarily from the mechanical fragility of such dielectrics, in which the undesirable scratches are prone to produce. To mitigate this problem, a new model is proposed to predict the initiation of scratching based on the mechanical properties of passive layer and copper substrate. In order to deduce the ratio of the passive layer yield strength to the substrate yield strength and the layer thickness, the limit analysis solution of surface scratch under Berkovich indenter is used to analyze the nano-scratch experimental measurements. The modulus of the passive layer can be calculated by the nano-indentation test combined with the FEM simulation. It is found that the film modulus is about 30% of the substrate modulus. Various regimes of scratching are delineated by FEM modeling and the results are verified by experimental data.
基金funded by the Engineering and Physical Sciences Research Council(EPSRC)under the grant EP/T01489X/1.
文摘In this study,a modeling approach based on smooth particle hydrodynamics(SPH)was implemented to simulate the nanoscale scratching process using conical tools with different negative rake angles.The implemented model enables the study of the topography of groove profiles,scratching forces,and the residual plastic strain beneath the groove.An elastoplastic material model was employed for the workpiece,and the tool–workpiece interaction was defined by a contact model adopted from the Hertz theory.An in-house Lagrangian SPH code was implemented to perform nano-scratching simulations.The SPH simulation results were compared with nanoscale scratching experimental data available in the literature.The simulation results revealed that the normal force was more dominant compared to the cutting force,in agreement with experimental results reported for a conical tip tool with a 60°negative rake angle.In addition,the simulated groove profile was in good agreement with the groove profile produced in the aforementioned experiment.The numerical simulations also showed that the normal and cutting forces increased with the increase in the scratching depth and rake angle.Although the cutting and ploughing mechanisms were noticed in nano-scratching,the ploughing mechanism was more dominant for increased negative rake angles.It was also observed that residual plastic strain exists below the groove surface,and that the plastically deformed layer thickness beneath a scratched groove is larger for more negative values of the tool rake angle and higher scratching depths.
