Objective To analyze the clinical characteristics of patients with presbycusis by using disyllabic mandarin speech test materials (MSTMs).Methods A total of 59 subjects (23 men and 36 women) with presbycusis,from 61 to 84 years old with the average as 71.3±6.7.They were divided into three groups:the mild group (10 subjects),the moderate group (35 subjects)and the severe group (14 subjects)according to the pure tone average (PTA) thresholds at 0.5,1,2 and 4 kHz from the better ear.In addition,11 subjects of elderly persons with normal hearing were used as the control group.All the subjects enrolled in this study could speak Mandarin well in their daily lives.Nine lists of disyllabic mandarin speech test materials were utilized to test speech recognition threshold (SRT) and P-I function for these groups respectively.Results The PTA(51.65±11.98)and SRT (50.98±16.05)from presbycusis group were much higher than the control group(PTA 19.55± 4.55,SRT 18.79± 7.45),while the average slope of the P-I function 2.63％/dB from the presbycusis group was lower than the control group 4.65％/dB (P＜0.01).The SRT of male patients (56.54±17.23) was higher than the females(47.99± 15.63) (P＜0.05).The PTA and SRT in these three groups divided by degrees of hearing loss were higher than the control group obviously.The PTA and SRT had significantly increased as the degree of hearing loss increased.The differences among these groups were significant (P＜0.01).The average slope of P-I function of these three groups divided by degrees of hearing loss (mild group:2.47％/dB,moderate group:2.76％/dB,severe group:2.42％/dB) was smaller than the slopes in the control group which was 4.65 ％/dB (P＜0.01).The average slope of P-I function among these groups had no significant difference (P＞0.05).Conclusion The SRT of patients with presbycusis increased and the SRT of male was higher than the females.The average slope of P-I function decreased and the curve moved to right side and became a gradual curve.As hearing loss became more severe,the SRT rose more apparently.

Microwave thermal ablation technology is widely used in the treatment of liver tumors because of its minimal invasiveness and small side effects. The precise control of the thermal dose largely determines the therapeutic effect of microwave thermal ablation. However, the current magnetron-based microwave thermal ablation device has the disadvantages of poor power output stability and high operating voltage. In view of the above problems, this paper selected the microwave solid-state source as the core device of microwave output, and designed a dual-frequency microwave thermal ablation system based on 2 450 MHz and 433 MHz. The system used the power detection circuit to perform PID feedback control on the actual output power of the system. The experimental results show that the maximum output power of the system is less than 1 W. The PID algorithm further enhances the accuracy and stability of the system output power while improving the system security. The dual-frequency microwave thermal ablation system designed in this paper can provide a safe and reliable experimental platform for subsequent research.
Catheter Ablation ; instrumentation ; Humans ; Liver Neoplasms ; therapy ; Microwaves ; Radiofrequency Ablation