Functionalizing and patterning of the silicon surface can be realized simultaneously by the chemomechanical method. The oxide-coated crystalline silicon （100） surface is scratched with a diamond tool in the presence...Functionalizing and patterning of the silicon surface can be realized simultaneously by the chemomechanical method. The oxide-coated crystalline silicon （100） surface is scratched with a diamond tool in the presence of aryldiazonium salt （C6H5N2BF4）. Scratching activates the silicon surface by removing the passivation oxide layer to expose fresh Si atoms. The sur- face morphologies before and after chemomechanical reaction are characterized with atomic force microscopy. Time-of-flight secondary ion mass spectroscopy confirms the presence of C6H5 and provides evidence for the formation of self-assembled monolayer （SAM） on silicon surface via Si-C covalent bonds by scratching the silicon in the presence of C6H5N2BF4. C6H5 groups further bond with surface Si atoms via Si-C covalent bonds as confirmed from infrared spectroscopy results. We propose that chemomechanical reaction, which occurred during scratching the silicon surface, produce C6H5 groups from aryldiazonium salt. The relevant adhesion of SAM is measured. It is found that SAM can reduce the adhesion of silicon. The monolayer can be used as anti-adhesion monolayer for micro/nanoelectromechanical systems components under different environments and operating conditions.展开更多
Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; ...Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; 52, to TD group. For each subject, the systolic pressure （SP）, diastolic pressure （DP） and pulse （ P ） were measured at five time-point： pre-treatment, initiation of carious removal, the end of carious removal, the end of the cavity restoration, and the end of the dental care. They were recorded as To, T1 , T2, T3, and TE, respectively. The difference of SP, DP, and P within each group were analyzed. Results Of all 105 subjects, 14 were administered local anesthesia. Since local anesthesia may be a confounding factor for changes in blood pressure and pulse, only the data of the other 91 subjects that local anesthesia were not administered were analyzed. Regarding the SP, DP, and P for TD, the difference between TO and T1 was significant （ P = 0. 013, 0. 015, 0. 012 respectively）, while not significant between T1 and T2, T2 and T3, T3 and TE（ P 〉0. 05）. Regarding the SP, DP, and P for CMCR, the differences were not significant between every two consecutive time-points （ P 〉 0. 05）. The differences of the SP, DP, and P between CMCR and TD were not significant for time-points T0, T3 and Te （p 〉 0. 05 ）, while significant for T1 and T2 （ P 〈 0. 05 ）. Conclusion In general, CMCR induces less increase of blood pressure and pulse in children compared to traditional drilling （TD）. It may be inferred that CMCR is less distressing than TD.展开更多
The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analy...The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analyze the energetics of the motor, we reconceptualize its chemomechanical cy- cle in terms of separate fuel reaction and work production processes and introduce a thermodynamic constraint to optimize the cycle. The model predicts that the load dependences of the motor＇s veloc- ity, stepping ratio, and dwell time are determined by the mechanical parameters of the motor-track system rather than the fuel reaction rate. This behavior is verified using reported experimental data from wild-type and elongated kinesins. The fuel reaction and work production processes indicate that kinesin is driven by switching between two chemical states, probably following a general pattern for molecular motors. The comparison with experimental data indicates that the fuel reaction processes are close to adiabatic, which is important for efficient operation of the motor. The model also suggests that a soft, short neck linker is important for the motor to maintain its load transport velocity.展开更多
Chemomechanics of materials is an exciting and fast growing field where mechanics meets chemistry. This perspective presents a brief overview of recent advance in the study of materials chemomechanics. We identify cha...Chemomechanics of materials is an exciting and fast growing field where mechanics meets chemistry. This perspective presents a brief overview of recent advance in the study of materials chemomechanics. We identify challenges and opportunities for tackling the long-standing and emerging problems for the field.展开更多
Materials chemomechanics is an exciting and fast growing field where mechanics meets chemistry, and has drawn increasing attention in recent years. It is concerned with the phenomena and mechanisms of coupled chemical...Materials chemomechanics is an exciting and fast growing field where mechanics meets chemistry, and has drawn increasing attention in recent years. It is concerned with the phenomena and mechanisms of coupled chemical and mechanical interactions. Chemomechanical coupling phenomena exist in many research areas, ranging from the development of advanced batteries, biomechanical engineering, hydrogen embrittlement, and high temperature oxidation. In fact, a typical chemomechanical problem usually involves the processes of diffusion, chemical reaction, deformation and stress generation. Such a strong coupling between chemistry and mechanics can give rise to the complex spatial-temporal evolution of composition, microstructure and morphology in materials.展开更多
基金We thank Prof. Yang Gan of Harbin Institute of Technology, and Prof. Fu-long Yuan of Heilongjiang University for the help in the experiments. This work was supported by the Center for Precision Engineering of Harbin Institute of Technology, the Youth the Colleges and Universities in Heilongjiang Province in 2010 （No.1155G54）, the Training Fund Project of Jiamusi University （No.RC2009-037）, and the National Natural Science Foundation of China （No.51105174）.
文摘Functionalizing and patterning of the silicon surface can be realized simultaneously by the chemomechanical method. The oxide-coated crystalline silicon （100） surface is scratched with a diamond tool in the presence of aryldiazonium salt （C6H5N2BF4）. Scratching activates the silicon surface by removing the passivation oxide layer to expose fresh Si atoms. The sur- face morphologies before and after chemomechanical reaction are characterized with atomic force microscopy. Time-of-flight secondary ion mass spectroscopy confirms the presence of C6H5 and provides evidence for the formation of self-assembled monolayer （SAM） on silicon surface via Si-C covalent bonds by scratching the silicon in the presence of C6H5N2BF4. C6H5 groups further bond with surface Si atoms via Si-C covalent bonds as confirmed from infrared spectroscopy results. We propose that chemomechanical reaction, which occurred during scratching the silicon surface, produce C6H5 groups from aryldiazonium salt. The relevant adhesion of SAM is measured. It is found that SAM can reduce the adhesion of silicon. The monolayer can be used as anti-adhesion monolayer for micro/nanoelectromechanical systems components under different environments and operating conditions.
基金Supported by Science and Technology Commission of Shanghai(074119644,09DZ2272100)Shanghai Leading Academic Discipline Project(S30206)
文摘Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; 52, to TD group. For each subject, the systolic pressure （SP）, diastolic pressure （DP） and pulse （ P ） were measured at five time-point： pre-treatment, initiation of carious removal, the end of carious removal, the end of the cavity restoration, and the end of the dental care. They were recorded as To, T1 , T2, T3, and TE, respectively. The difference of SP, DP, and P within each group were analyzed. Results Of all 105 subjects, 14 were administered local anesthesia. Since local anesthesia may be a confounding factor for changes in blood pressure and pulse, only the data of the other 91 subjects that local anesthesia were not administered were analyzed. Regarding the SP, DP, and P for TD, the difference between TO and T1 was significant （ P = 0. 013, 0. 015, 0. 012 respectively）, while not significant between T1 and T2, T2 and T3, T3 and TE（ P 〉0. 05）. Regarding the SP, DP, and P for CMCR, the differences were not significant between every two consecutive time-points （ P 〉 0. 05）. The differences of the SP, DP, and P between CMCR and TD were not significant for time-points T0, T3 and Te （p 〉 0. 05 ）, while significant for T1 and T2 （ P 〈 0. 05 ）. Conclusion In general, CMCR induces less increase of blood pressure and pulse in children compared to traditional drilling （TD）. It may be inferred that CMCR is less distressing than TD.
基金This work was supported by the National Natural Science Foundation of China under Crant No. 11774284 （to H. R. Li） and Grant No. 11534008.
文摘The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate di- rectional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analyze the energetics of the motor, we reconceptualize its chemomechanical cy- cle in terms of separate fuel reaction and work production processes and introduce a thermodynamic constraint to optimize the cycle. The model predicts that the load dependences of the motor＇s veloc- ity, stepping ratio, and dwell time are determined by the mechanical parameters of the motor-track system rather than the fuel reaction rate. This behavior is verified using reported experimental data from wild-type and elongated kinesins. The fuel reaction and work production processes indicate that kinesin is driven by switching between two chemical states, probably following a general pattern for molecular motors. The comparison with experimental data indicates that the fuel reaction processes are close to adiabatic, which is important for efficient operation of the motor. The model also suggests that a soft, short neck linker is important for the motor to maintain its load transport velocity.
文摘Chemomechanics of materials is an exciting and fast growing field where mechanics meets chemistry. This perspective presents a brief overview of recent advance in the study of materials chemomechanics. We identify challenges and opportunities for tackling the long-standing and emerging problems for the field.
文摘Materials chemomechanics is an exciting and fast growing field where mechanics meets chemistry, and has drawn increasing attention in recent years. It is concerned with the phenomena and mechanisms of coupled chemical and mechanical interactions. Chemomechanical coupling phenomena exist in many research areas, ranging from the development of advanced batteries, biomechanical engineering, hydrogen embrittlement, and high temperature oxidation. In fact, a typical chemomechanical problem usually involves the processes of diffusion, chemical reaction, deformation and stress generation. Such a strong coupling between chemistry and mechanics can give rise to the complex spatial-temporal evolution of composition, microstructure and morphology in materials.
