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Objective To compare the disinfection effect of 3% (v/v) hydrogen peroxide and 500 mg/L chlorine-containing disinfectants in the independent waterway of a periodontal ultrasonic scaler to provide a reference for clinical waterway disinfection management in stomatology departments. Methods The 18 ultrasonic scalers were randomly divided into 3 groups of 6 units: the control group, experimental group 1 (3% hydrogen peroxide disinfectant group), and experimental group 2 (500 mg/L chlorine-containing disinfectant group). The replaceable parts of the independent waterway pipes of the 3 groups of ultrasonic scalers were replaced, and the water supply was supplied with sterile distilled water (DW). In the control group, special treatment was not applied to the nonreplaceable pipe part. In experimental group 1, the 3% hydrogen peroxide was used to disinfect nonreplaceable pipelines. In experimental group 2, the nonreplaceable part was disinfected with the 500 mg/L chlorine-containing disinfectant. The water sample was taken from the outlet of the scaler working part in the three groups for monitoring before disinfection, immediately after disinfection and 10 consecutive days after disinfection. Bacteria in the water samples were cultured for the colony counts. Then, the bacterial culture data were compared between groups. The qualified criterion of the water sample was that the number of bacterial colonies was less than or equal to 100 CFU/mL. After disinfection, a bacterial species mass spectrometry identification analysis was carried out when the number of bacterial colonies in each group exceeded the standard for the first time. Biofilms from the inner wall of the tube in the three groups were observed under an electron microscope on the 10th day after disinfection. Results There were no significant differences between the three groups before disinfection (F = 2.549, P = 0.111). The number of bacterial colonies in the spout of 6 scalers in the control group all exceeded the standard, and three kinds of bacteria were cultured: Sphingomonas melonis, Herbaspirillum huttiense, and Ralstonia pickettii. Compared with those in the control group, the number of bacterial colonies in experimental group 1 decreased significantly for 1-2 days after disinfection (P

The measurement of downhole drilling motor rotational speed is crucial for optimizing drilling operations, improving work efficiency, and preventing equipment failures. However, traditional downhole rotational speed sensors suffer from power supply limitations, which can increase drilling costs. To address this issue, this study presents a novel multifunctional rotational speed sensor based on triboelectric nanogenerator (TENG) technology, enabling the self-powered measurement of rotational speed, direction, and angle. Our experimental results demonstrate that the sensor operates stably within a temperature range of 0 to 150 °C and a humidity range of 0 to 90%. It achieves rotational speed measurement with an accuracy of less than 2.5% error within a range of 0 to 1000 rpm, angular measurement with a resolution of 60 degrees and an error of less than 2% within a range of 0 to 360 degrees, and rotational direction measurement. Furthermore, the sensor exhibits self-powered functionality, achieving a maximum power output of 29.1 μW when the external load is 10 MΩ. Compared to conventional rotational speed sensors, this sensor possesses the unique advantage of integrating the measurement of rotational speed, angle, and direction, while simultaneously harnessing downhole working conditions for self-power generation. These characteristics make it highly suitable for practical downhole environments. [ABSTRACT FROM AUTHOR]

The bypass valve of a positive displacement motor is a key component for regulating the bottom hole pressure and ensuring the normal circulation of drilling fluid during the drilling process. Severe erosion damage to the bypass valve significantly affects the service life of the positive displacement motor, yet there is currently a lack of related research. In this research, the flow characteristics of drilling fluid inside the valve core were analyzed through flow field simulation, and the main factors influencing erosion damage to the valve core were investigated. The results indicate that the side holes and flow channel structure of the valve core are the main causes of erosion. Based on this, two optimization schemes are proposed, namely, reducing the number of bypass side holes to 4 and optimizing the flow channel cone angle to 45°. The simulation results show that the erosion rate of the optimized valve core is significantly reduced, and the service life is effectively improved. Finally, a valve core life prediction model is established using a back propagation (BP) neural network to evaluate the optimization effect. The results show that the applicable flow range and maximum service life of the optimized valve core are increased by approximately 60% and 75.4%, respectively, validating the effectiveness of the optimization scheme. [ABSTRACT FROM AUTHOR]