Carbon fiber microelectrodes (CFEs) are useful when combined with electrochemical techniques for measuring changes in neurotransmitter concentrations. We addressed conflicting details regarding the use of CFEs. Experi...Carbon fiber microelectrodes (CFEs) are useful when combined with electrochemical techniques for measuring changes in neurotransmitter concentrations. We addressed conflicting details regarding the use of CFEs. Experimental groups consisted of CFEs at different ages (1 week, 1 month, or 2 months), cleaned in solvents (isopropanol or xylene), and exposed to in vitro use (flow cell calibrations) or in vivo use (in brain tissue). In order to determine if any of these factors affect CFE sensitivity, the present study utilized fixed potential amperometry and a flow injection system to calibrate CFEs for the measurement of dopamine. The sensitivity index (nA/μM per 100 μm of exposed carbon fiber) was not affected by the age of CFEs or pre-cleaning with xylene or isopropanol. CFE sensitivity of the in vitro exposure group also did not differ from untreated CFEs, indicating the calibration process did not alter sensitivity. However, in vivo use in brain tissue did reduce sensitivity. This effect was negated and sensitivity restored by cleaning CFEs in isopropanol or xylene following in vivo brain recordings. Given that variations in CFE sensitivity can skew results, our findings can help standardize CFE use and explain discrepancies between researchers.展开更多
The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded wi...The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.展开更多
In this paper, by using high-speed camera, CCD camera, signal and graph acquisition system, and other experimental instruments, investigation on liquid-gas two-phase flow in diesel fuel injection system and their effe...In this paper, by using high-speed camera, CCD camera, signal and graph acquisition system, and other experimental instruments, investigation on liquid-gas two-phase flow in diesel fuel injection system and their effect on engine performances were made. Emerging and bursting of cavitation in the cavity above pump delivery valve, in injection pipe, and in fuel trough of injector of the fuel injection system were observed and mechanism of cavitation were discussed. Effects of liquid-gas two-phase flow on propagation velocity of pressure wave of the system and on irregular injection were analyzed. Two types of cavitation, long Living time cavitation and short living time cavitation, in the cavity above pump delivery valve of diesel fuel injection system were observed.展开更多
文摘Carbon fiber microelectrodes (CFEs) are useful when combined with electrochemical techniques for measuring changes in neurotransmitter concentrations. We addressed conflicting details regarding the use of CFEs. Experimental groups consisted of CFEs at different ages (1 week, 1 month, or 2 months), cleaned in solvents (isopropanol or xylene), and exposed to in vitro use (flow cell calibrations) or in vivo use (in brain tissue). In order to determine if any of these factors affect CFE sensitivity, the present study utilized fixed potential amperometry and a flow injection system to calibrate CFEs for the measurement of dopamine. The sensitivity index (nA/μM per 100 μm of exposed carbon fiber) was not affected by the age of CFEs or pre-cleaning with xylene or isopropanol. CFE sensitivity of the in vitro exposure group also did not differ from untreated CFEs, indicating the calibration process did not alter sensitivity. However, in vivo use in brain tissue did reduce sensitivity. This effect was negated and sensitivity restored by cleaning CFEs in isopropanol or xylene following in vivo brain recordings. Given that variations in CFE sensitivity can skew results, our findings can help standardize CFE use and explain discrepancies between researchers.
基金the CDCHTA of the University of Los Andes for providing financial support through several approved projectsthe National Fund for Science, Technology and Innovation (FONACIT) of Venezuelan Ministry of Science and Technology for providing financial support, SPE 112–370 and Project G-2005000641
文摘The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.
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文摘In this paper, by using high-speed camera, CCD camera, signal and graph acquisition system, and other experimental instruments, investigation on liquid-gas two-phase flow in diesel fuel injection system and their effect on engine performances were made. Emerging and bursting of cavitation in the cavity above pump delivery valve, in injection pipe, and in fuel trough of injector of the fuel injection system were observed and mechanism of cavitation were discussed. Effects of liquid-gas two-phase flow on propagation velocity of pressure wave of the system and on irregular injection were analyzed. Two types of cavitation, long Living time cavitation and short living time cavitation, in the cavity above pump delivery valve of diesel fuel injection system were observed.
