A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential...A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential and convert the voltage for outPut; specific program runs in the PC to regulate and control the system. The effect of the proportion factor Kp on the control variation is researched through certain experiment. Two experiments, the control of electrolysis in constant poteniial and the determination of polarization curves, are designed to test and evaluate the effectiveness of the device. The experimemel results show that the variation between the actualanode potential and the target potential could be controlled to below 1 mV if Kp is set to an appropriate value.展开更多
Background Magnetic resonance imaging （MRI） is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceram...Background Magnetic resonance imaging （MRI） is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceramic crowns in MRI, in order to analyze their influences on diagnostic interpretation of MRI. Methods Galvano-ceramic and metal-ceramic crowns （Bio98, Wiron99, SP-78, BioKC97） were fabricated with the same model. All materials were imaged by means of 1.5T MRI apparatus with three different sequences, T1-weighted spin-echo （T1-weighted SE）, T2-weighted spin-echo （T2-weighted SE） and Gradient echo （GE）. Mean and standard deviation of distilled water signal intensity （St） around the sample in the region of interest （500 mm^2） enclosing the whole artifacts were determined, and compared for evaluation of the homogeneity of signal intensity. Images around the sample were acquired and evaluated. Results There were statistically significant differences in the values of signal intensity between acrylic resin control and BioKC97, Wiron99 in the three sequences （P〈0.001）. The mean values of signal intensity for Bio98, SP-78 were significantly different from that of acrylic resin control （RE） in GE sequence （P〈0.001）. No difference was showed between acrylic resin control and galvano-ceramic crown （P 〉0.05）. Images showed that the greatest artifact was a 25 mm ring with distortion in Wiron99 in GE sequence. Conclusions This in vitro study suggested that galvano-ceramic crown had no influence on the MRI, while metal-ceramic crowns caused moderate artifacts in the MRI. Therefore, galvano-ceramic restoration is a valuable alternative in dentistry.展开更多
The purpose of this study is to discuss the microstructure and properties variation of the weld metal in the dissimilar stainless steels during the argon tungsten-arc welding process.Because of the existence of differ...The purpose of this study is to discuss the microstructure and properties variation of the weld metal in the dissimilar stainless steels during the argon tungsten-arc welding process.Because of the existence of different materials and chemistry variation within welds,properties,such as tensile and fracture properties and so on,are expected to show spatial variation.In the study,microstructures were observed by optical and electron microscopy.Good appearance and uniform structure and typical dendrite structure were observed in welding joint.The micro-hardness tester and electronic universal stretcher were used to measure the mechanical properties of the weldments and base metals.The heat affected zone（HAZ） near 1Cr13 hardness is up to peak value of 1150 HV,the strength of weldments is nearly same as austenite stainless steel.In addition,through seawater immersion test,polarization curves and AC impedance spectroscopy of the weldments and base metals are obtained.It was found that corrosion resistance at welding joint lies between 1C13 and 1Cr18Ni9Ti.展开更多
文摘A set of device is designed based on PC to realize the functions of traditional potentiostats in the phase ana1ysis of galvanochemistry. In the device, A/D and D/A conversion is used to measure the electrode potential and convert the voltage for outPut; specific program runs in the PC to regulate and control the system. The effect of the proportion factor Kp on the control variation is researched through certain experiment. Two experiments, the control of electrolysis in constant poteniial and the determination of polarization curves, are designed to test and evaluate the effectiveness of the device. The experimemel results show that the variation between the actualanode potential and the target potential could be controlled to below 1 mV if Kp is set to an appropriate value.
文摘Background Magnetic resonance imaging （MRI） is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceramic crowns in MRI, in order to analyze their influences on diagnostic interpretation of MRI. Methods Galvano-ceramic and metal-ceramic crowns （Bio98, Wiron99, SP-78, BioKC97） were fabricated with the same model. All materials were imaged by means of 1.5T MRI apparatus with three different sequences, T1-weighted spin-echo （T1-weighted SE）, T2-weighted spin-echo （T2-weighted SE） and Gradient echo （GE）. Mean and standard deviation of distilled water signal intensity （St） around the sample in the region of interest （500 mm^2） enclosing the whole artifacts were determined, and compared for evaluation of the homogeneity of signal intensity. Images around the sample were acquired and evaluated. Results There were statistically significant differences in the values of signal intensity between acrylic resin control and BioKC97, Wiron99 in the three sequences （P〈0.001）. The mean values of signal intensity for Bio98, SP-78 were significantly different from that of acrylic resin control （RE） in GE sequence （P〈0.001）. No difference was showed between acrylic resin control and galvano-ceramic crown （P 〉0.05）. Images showed that the greatest artifact was a 25 mm ring with distortion in Wiron99 in GE sequence. Conclusions This in vitro study suggested that galvano-ceramic crown had no influence on the MRI, while metal-ceramic crowns caused moderate artifacts in the MRI. Therefore, galvano-ceramic restoration is a valuable alternative in dentistry.
文摘The purpose of this study is to discuss the microstructure and properties variation of the weld metal in the dissimilar stainless steels during the argon tungsten-arc welding process.Because of the existence of different materials and chemistry variation within welds,properties,such as tensile and fracture properties and so on,are expected to show spatial variation.In the study,microstructures were observed by optical and electron microscopy.Good appearance and uniform structure and typical dendrite structure were observed in welding joint.The micro-hardness tester and electronic universal stretcher were used to measure the mechanical properties of the weldments and base metals.The heat affected zone（HAZ） near 1Cr13 hardness is up to peak value of 1150 HV,the strength of weldments is nearly same as austenite stainless steel.In addition,through seawater immersion test,polarization curves and AC impedance spectroscopy of the weldments and base metals are obtained.It was found that corrosion resistance at welding joint lies between 1C13 and 1Cr18Ni9Ti.
