Objective:To design the liquid level detection system by ultrasonic method to meet the requirements of automatic enzyme immunoassay workstations and have a precise detection of liquid level. Methods:Because the existing sample needle should move down, liquid surface and the poor conductivity of liquid were invalid. So a method of ultrasonic liquid level detection system was designed. The control signal was launched by a microprocessor to control ultrasonic signal generator chip and the ultrasonic signal reflected when the liquid level in a test tube or microplate. Results: By receiving the reflection echo signal sent to the microprocessor for signal processing, the liquid level was detected. Conclusion: The ultrasonic method applied to the liquid level detection system to overcome the above shortcomings, improve pipetting accuracy and avoid cross pollution, so as to meet the requirement of the automatic enzyme immunoassay workstation test.

BACKGROUND: Proximal femoral nail is the first choice for treating intertrochanteric fractures. The studies concerning proximal femoral nail for senile intertrochanteric fractures mainly focus on proximal femoral nail antirotation/proximal femoral nail antirotation II, Gamma 3 and intertrochanteric antegrade nail. OBJECTIVE: To investigate the clinical efficacy of proximal femoral nail antirotation II versus intertrochanteric antegrade nail in the treatment of intertrochanteric fracture in the elderly. METHODS: Forty-two cases of senile intertrochanteric fractures at Department of Orthopedics, First People’s Hospital of Xuancheng City from January 2016 to December 2018 were included, involving 15 males and 27 females, aged 65-90 years. Among which, 22 patients received internal fixation using proximal femoral nail antirotation II and 20 patients using intertrochanteric antegrade nail. The operation time, intraoperative blood loss, fracture healing time, postoperative complications and the hip function scores at last follow-up were compared. The study was approved by the Ethics Committee of First People’s Hospital of Xuancheng City, approval No. (2015)(17). RESULTS AND CONCLUSION: (1) The operation time in the proximal femoral nail antirotation group was shorter than that in the intertrochanteric antegrade nail group [(69.4±11.5), (90.0±9.7) minutes, P < 0.05]. The intraoperative blood loss in the proximal femoral nail antirotation group was less than that in the intertrochanteric antegrade nail group [(70.6±10.0), (86.5±11.1) mL, P < 0.05]. (2) There was no significant difference in the fracture healing time between two groups [(4.3±0.5), (4.1±0.4) months, P > 0.05]. (3) In the proximal femoral nail antirotation group, three cases suffered from pain at the affected limb, and one case of coxa vara deformity. One case in the intertrochanteric antegrade nail group appeared with pain at the affected limb. The postoperative incidence of complications between two groups showed no significant difference (18.2%, 5.0%, P > 0.05). (4) No significant difference was found in the Harris scores at the last follow-up between two groups (90.3±2.8, 91.5±2.4, P > 0.05). (5) There were no fracture adverse reactions related to internal fixation materials in the two groups. (6) In summary, proximal femoral nail antirotation II and intertrochanteric antegrade nail internal fixation are effective methods for intertrochanteric fractures in the elderly. However, proximal femoral nail antirotation II has short operation time and few intraoperative blood losses.