The behavior of gaseous nitriding on the surface nanocrystallized (SNCed) steel was investigated. The mild steel discs were SNCed on one side by using the method of ultrasonic shot peening. The opposite side of the di...The behavior of gaseous nitriding on the surface nanocrystallized (SNCed) steel was investigated. The mild steel discs were SNCed on one side by using the method of ultrasonic shot peening. The opposite side of the discs maintained the original coarse-grained condition. The gaseous nitriding was subsequently carried out at three different temperatures: 460, 500 and 560℃. The compound layer growth and diffusion behavior were then studied. It was revealed that SNC pretreatment greatly enhances both diffusion coefficient D and surface reaction rate. As a result, nitriding time could be reduced to the half. It was also found that the growth of compound layer with nitriding time conformed with parabolic relationship from the start of nitriding process in the SNCed samples.展开更多
By using the concept of modified structural number(SNC)and deflection measurements,a simplified calculation methodology,that permits the structural condition evaluation of an existing pavement,is being proposed.The va...By using the concept of modified structural number(SNC)and deflection measurements,a simplified calculation methodology,that permits the structural condition evaluation of an existing pavement,is being proposed.The values of SNC and the curvature parameters were first determined through simulations using the ELSYM-5 software.Deflection measurements were carried out in experimental segments of Brazilian highways.The resilient moduli of each layer were determined from backcalculation using the ELMOD program for a three-layer system.Theoretical correlation models between SNC and the basin deformation parameter were determined and later,calibrated with the results of experimental sections.Utilizing the studied models,a good correlation was found between SNC,area parameter and maximum deflection,enabling the determination of SNC through deflection measurements and assisting in the diagnostic of structural condition of asphalt pavements.展开更多
Using a gas-solid two-phase model(a discrete phase model),the authors investigated the flow field inside the multi-channel nozzle for surface nanocrystallization(SNC)induced by the ultrasonic particulate peening(USPP)...Using a gas-solid two-phase model(a discrete phase model),the authors investigated the flow field inside the multi-channel nozzle for surface nanocrystallization(SNC)induced by the ultrasonic particulate peening(USPP).By computation,the velocity fields of both the gas and the solid phases were simulated and the track of the solid phase was analyzed in detail.It can be found that the velocities of the two phases are able to reach an ultrasonic level;meanwhile,the dispersion width of the solid phase at the nozzle exit is less than that of the gas phase.When particle diameters are less than 5 μm,there is a decreasing trend in the dispersion width of the solid phase with an increase in particle diameters.The trend becomes stable as the particle diameters are greater than 5 μm;in the meantime,the distribution of solid particles is near the axis of the jet flow.The optimal standoff distance between the nozzle and the substrate in the process of USPP is about 120 mm.Simulation results can help improve the design of mass-production-oriented multi-channel nozzles for SNC induced by USPP.展开更多
A spontaneous mutation in the Albino Swiss (AS) rat has been shown to be a single point mutation (agu) in the gene coding for the gamma isoform of protein kinase C (PKC-γ). The characteristics of the mutant include m...A spontaneous mutation in the Albino Swiss (AS) rat has been shown to be a single point mutation (agu) in the gene coding for the gamma isoform of protein kinase C (PKC-γ). The characteristics of the mutant include movement disorders, a failure to release dopamine in the striatum and elevations of molecules such as parkin and ubiquitin in the substantia nigra pars compacta (SNC). This present study examined SNC cell bodies and dopaminergic synaptic terminals within the caudate-putamen. Cell volume and nuclear volume were reduced in the AS/AGU mutant compared to the AS control, but the volume fractions of mitochondria and rough endoplasmic reticulum were significantly higher. No Lewy bodies were present in the mutant, although microglia were found adjacent to some SNC cells. Dopaminergic terminals were identified in the caudate-putamen by electron microscopy with low-glutaraldehyde fixation and immunohistochemistry for tyrosine hydroxylase using immuno-gold visualisation. AS/AGU mutant rats had less than half of the synaptic vesicles of AS controls;this was not only true of “readily-releasable” zones adjacent to the synaptic cleft but also “storage pool” zones. The findings support the hypothesis that the initial bar to dopamine availability in the striatum is the reduced release, with nigral cell death being a later phenomenon.展开更多
Cathodic polarization curve and electrochemical impedance spectroscopy in 30% NaOH solution were utilized to investigate the hydrogen evolution （HE） behavior of interstitial free （IF） steel surface nanocrystalliz...Cathodic polarization curve and electrochemical impedance spectroscopy in 30% NaOH solution were utilized to investigate the hydrogen evolution （HE） behavior of interstitial free （IF） steel surface nanocrystallized （SNC） via ultrasonic particulate peening （USPP）. The surface morphology and grain size of the steel were analyzed by scanning electronic microscope （SEM） and X-ray diffraction （XRD）. It was found that the IF steel treated by SNC and SNC ＋ 1% roiling got reductions of 200 mV and 300 mV in HE over-potentials ,respectively. Their real surface areas are enlarged by about 20 times and the hydrogen evolution reaction activation flee energies are about 50% of the original IF steels＇ s activation free energy.展开更多
Summary Salicylic acid （SA） is an essential defence hormone in plants. Upon pathogen infection, induced biosynthesis of SA is mediated by Isochorismate synthase 1 （ICS1）, whose gene transcription is controlled mai...Summary Salicylic acid （SA） is an essential defence hormone in plants. Upon pathogen infection, induced biosynthesis of SA is mediated by Isochorismate synthase 1 （ICS1）, whose gene transcription is controlled mainly through two redundant transcription factors, SAR Deficient 1 （SARD0 and Calmodulin- binding protein 6o-like g （CBP60g）.展开更多
文摘The behavior of gaseous nitriding on the surface nanocrystallized (SNCed) steel was investigated. The mild steel discs were SNCed on one side by using the method of ultrasonic shot peening. The opposite side of the discs maintained the original coarse-grained condition. The gaseous nitriding was subsequently carried out at three different temperatures: 460, 500 and 560℃. The compound layer growth and diffusion behavior were then studied. It was revealed that SNC pretreatment greatly enhances both diffusion coefficient D and surface reaction rate. As a result, nitriding time could be reduced to the half. It was also found that the growth of compound layer with nitriding time conformed with parabolic relationship from the start of nitriding process in the SNCed samples.
文摘By using the concept of modified structural number(SNC)and deflection measurements,a simplified calculation methodology,that permits the structural condition evaluation of an existing pavement,is being proposed.The values of SNC and the curvature parameters were first determined through simulations using the ELSYM-5 software.Deflection measurements were carried out in experimental segments of Brazilian highways.The resilient moduli of each layer were determined from backcalculation using the ELMOD program for a three-layer system.Theoretical correlation models between SNC and the basin deformation parameter were determined and later,calibrated with the results of experimental sections.Utilizing the studied models,a good correlation was found between SNC,area parameter and maximum deflection,enabling the determination of SNC through deflection measurements and assisting in the diagnostic of structural condition of asphalt pavements.
基金supported by the National High-Tech.R&D Program of China(the National 863 plans projects,Grant No.2007AA03Z352)
文摘Using a gas-solid two-phase model(a discrete phase model),the authors investigated the flow field inside the multi-channel nozzle for surface nanocrystallization(SNC)induced by the ultrasonic particulate peening(USPP).By computation,the velocity fields of both the gas and the solid phases were simulated and the track of the solid phase was analyzed in detail.It can be found that the velocities of the two phases are able to reach an ultrasonic level;meanwhile,the dispersion width of the solid phase at the nozzle exit is less than that of the gas phase.When particle diameters are less than 5 μm,there is a decreasing trend in the dispersion width of the solid phase with an increase in particle diameters.The trend becomes stable as the particle diameters are greater than 5 μm;in the meantime,the distribution of solid particles is near the axis of the jet flow.The optimal standoff distance between the nozzle and the substrate in the process of USPP is about 120 mm.Simulation results can help improve the design of mass-production-oriented multi-channel nozzles for SNC induced by USPP.
文摘A spontaneous mutation in the Albino Swiss (AS) rat has been shown to be a single point mutation (agu) in the gene coding for the gamma isoform of protein kinase C (PKC-γ). The characteristics of the mutant include movement disorders, a failure to release dopamine in the striatum and elevations of molecules such as parkin and ubiquitin in the substantia nigra pars compacta (SNC). This present study examined SNC cell bodies and dopaminergic synaptic terminals within the caudate-putamen. Cell volume and nuclear volume were reduced in the AS/AGU mutant compared to the AS control, but the volume fractions of mitochondria and rough endoplasmic reticulum were significantly higher. No Lewy bodies were present in the mutant, although microglia were found adjacent to some SNC cells. Dopaminergic terminals were identified in the caudate-putamen by electron microscopy with low-glutaraldehyde fixation and immunohistochemistry for tyrosine hydroxylase using immuno-gold visualisation. AS/AGU mutant rats had less than half of the synaptic vesicles of AS controls;this was not only true of “readily-releasable” zones adjacent to the synaptic cleft but also “storage pool” zones. The findings support the hypothesis that the initial bar to dopamine availability in the striatum is the reduced release, with nigral cell death being a later phenomenon.
基金supported by the National High-Tech. R & D Program of China,Grant No. 2007AA03Z352
文摘Cathodic polarization curve and electrochemical impedance spectroscopy in 30% NaOH solution were utilized to investigate the hydrogen evolution （HE） behavior of interstitial free （IF） steel surface nanocrystallized （SNC） via ultrasonic particulate peening （USPP）. The surface morphology and grain size of the steel were analyzed by scanning electronic microscope （SEM） and X-ray diffraction （XRD）. It was found that the IF steel treated by SNC and SNC ＋ 1% roiling got reductions of 200 mV and 300 mV in HE over-potentials ,respectively. Their real surface areas are enlarged by about 20 times and the hydrogen evolution reaction activation flee energies are about 50% of the original IF steels＇ s activation free energy.
基金supported by grants from the Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery programthe Dewar Cooper Memorial Fund from the University of British Columbia(UBC)+1 种基金partially supported by a 4YF scholarship from UBCpartially supported by a Chinese Scholarship Council(CSC)fellowship
文摘Summary Salicylic acid （SA） is an essential defence hormone in plants. Upon pathogen infection, induced biosynthesis of SA is mediated by Isochorismate synthase 1 （ICS1）, whose gene transcription is controlled mainly through two redundant transcription factors, SAR Deficient 1 （SARD0 and Calmodulin- binding protein 6o-like g （CBP60g）.
