ABSTRACT
Objective To study the effect of the preset temperature,heating time and the spacing of radio frequency electrodes.Methods Fresh egg white was used to study the effects of heater spacing,temperature and heating time.Two electrodes were fixed to keep the needles perpendicular to the center of egg white confined on a square plate.Temperatures from 50 to 90℃ were tested with heating times of 60 and 120 seconds and electrode spac ings of 2.0,1.0,0.5 and 0.25 centimetres.The real-time temperature and the time to the appearance of a spindleshaped bridge between the electrodes was observed.The egg white's impedance and resistance,the lowest temperature of denaturation,and the mass (or volume) denatured at different time points were also observed.Results With an electrode spacing of 2 cm and the thermostat set at 63℃,the true electrode temperatures were 63.7 and 52.6℃,with the secondary electrode the cooler.Significant differences between the secondary electrode temperature and the preset temperature as well as the temperature between the primary and the secondary electrodes were observed.It was also found that different electrode spacing caused significant differences between the preset temperature and the primary as well as the secondary electrode temperature.Denaturation began at 56℃ with a spacing of 0.25 cm.At spacings of 0.25 and 0.50 cm,a spindle-shaped connection between the two electrodes was observed at temperatures above 70℃,but higher temperature was required at 1.00 and 2.00 cm.When the spacing was 0.25 cm and the preset temperature was 75℃,the denatured volume after 60 s of heating was 90.21+0.64 mm3.Heating for 120 s denatured 95.08+ 0.53 mm3 and two 60.s heatings 92.88+0.74 mm3,all significant differences.There were no significant differences in the resistance of the egg white before and after a single heating for 60 s,but after a single heating lasting 120 s it had increased significantly from 128.41+8.04 to 121.29±8.04 Ω.Conclusion Bipolar radio frequency heating can denature egg white.Higher temperature,longer heating and smaller electrode spacing heat more effectively.
ABSTRACT
Objective To explore if continuous administration of adenosine by peripheral pathway can attenuate myocardial hypertrophy and pulmonary arterial hypertension(PAH)caused by chronic hypoxia and analyze the dose-effect relationships between them.Methods Forty-eight Sprague-Dawley(SD)rats were randomly divided into 8 groups:the hypoxia group(n=6),the hypoxia ade-nosine-treated groups [n=18,adenosine was administrated with different doses 50,100,150 ?g/(kg?min),the hypoxia adenosine-treated group A,B,C],the control group(n=6),the control adenosine-treated control groups [n=18,adenosine was administrated with different doses 50,100,150 ?g/(kg?min),the control adenosine-treated control group A,B,C].On the 21st day of the experiment,the Medlab-U/4CS was used to determined the right ventricular systolic pressure(RVSP)and the mean pulmonary arterial pressure(mPAP)of each rat.The ratio of the weight of right ventricle/left ventricle and septum[RV/(LV+S)] and the ratio of the weight of right ventricle/body weight(RV/BW)were also calculated.The morphological changes in myocardium cells and pulmonary vascular structure were observed.SAS 8.0 software was used to analyze the data.Results Twenty-one days after hypoxia,RVSP,mPAP,RV/(LV+S),RV/BW in hypoxia groups were higher significantly than those in control group and hypoxia adenosine-treated groups(Pa