Homocysteine and Lp-PLA2 levels: Diagnostic value in coronary heart disease.

Coronary heart disease (CHD) is the leading cause of mortality worldwide. Identifying effective diagnostic markers and understanding risk factors is crucial for prevention and management. This study aimed to investigate the levels of homocysteine (Hcy) and lipoprotein-associated phospholipase A2 (Lp-PLA2) in human plasma and their roles in the diagnosis and prognosis of CHD. A retrospective study was conducted on 232 patients with CHD, divided into Acute Myocardial Infarction, unstable angina pectoris, and stable angina pectoris groups, and a control group of 75 healthy adults. Blood samples were analyzed for serum Hcy and Lp-PLA2 levels using the cycling enzyme method and ELISA method, respectively. Statistical analyses were performed to evaluate the risk factors, and diagnostic efficacy was assessed using receiver operating characteristic (ROC) curves. No significant differences in age and sex were observed between the study and control groups, whereas marked disparities in risk factors such as obesity, hypertension, diabetes, and hyperlipidemia were noted. Significant differences in serum Hcy and Lp-PLA2 levels were identified among the CHD subgroups. Univariate and multivariate logistic regression analyses revealed that Hcy, Lp-PLA2, hypertension, and hyperlipidemia were significant risk factors for CHD. The combined diagnostic Area Under the Curve (AUC) for Hcy and Lp-PLA2 was found to be higher than that when using them individually. This study identified the elevation of Hcy and Lp-PLA2 levels as independent risk factors for CHD, and their conjoint analysis significantly enhanced clinical diagnostic efficacy. These findings provide valuable insights for CHD diagnosis, treatment, and prevention, highlighting the importance of these markers in CHD management.

A Study on the Model of Detecting the Liquid Level of Sealed Containers Based on Kirchhoff Approximation Theory.

By simulating the sound field of a round piston transducer with the Kirchhoff integral theorem and analyzing the shape of ultrasound beams and propagation characteristics in a metal container wall, this study presents a model for calculating the echo sound pressure by using the Kirchhoff paraxial approximation theory, based on which and according to different ultrasonic impedance between gas and liquid media, a method for detecting the liquid level from outside of sealed containers is proposed. Then, the proposed method is evaluated through two groups of experiments. In the first group, three kinds of liquid media with different ultrasonic impedance are used as detected objects; the echo sound pressure is calculated by using the proposed model under conditions of four sets of different wall thicknesses. The changing characteristics of the echo sound pressure in the entire detection process are analyzed, and the effects of different ultrasonic impedance of liquids on the echo sound pressure are compared. In the second group, taking water as an example, two transducers with different radii are selected to measure the liquid level under four sets of wall thickness. Combining with sound field characteristics, the influence of different size transducers on the pressure calculation and detection resolution are discussed and analyzed. Finally, the experimental results indicate that measurement uncertainly is better than ±5 mm, which meets the industrial inspection requirements.

A Novel Ultrasonic Method for Liquid Level Measurement Based on the Balance of Echo Energy.

This study presents a novel method for determining the liquid level from the outside of a sealed container, which is based on the balance of echo energy received by two receiving sensors. The proposed method uses one transmitting transducer and two receiving sensors that are encapsulated in a coupling plane and arranged by certain rules. The calculation and comparison of echo energy are grounded on the difference ultrasonic impedance between gas and liquid media. First, by analyzing the propagation and attenuation characteristics of ultrasonic waves in a solid, an acoustic model for calculating the echo energy is established and simulated in MATLAB. Second, the proposed method is evaluated through a series of experiments. The difference and ratio of echo energy received by two receiving sensors are calculated and compared under two different coupling conditions. Two kinds of the sensors that are arranged by different rules are selected for measuring the liquid level, and the measurement are analyzed and discussed in detail. Finally, the experimental results indicate that the proposed method can meet the proposed accuracy requirements and can effectively solve the problems caused by some poor coupling conditions.

A Liquid Level Measurement Technique Outside a Sealed Metal Container Based on Ultrasonic Impedance and Echo Energy.

The proposed method for measuring the liquid level focuses on the ultrasonic impedance and echo energy inside a metal wall, to which the sensor is attached directly, not on ultrasonic waves that penetrate the gas-liquid medium of a container. Firstly, by analyzing the sound field distribution characteristics of the sensor in a metal wall, this paper proposes the concept of an "energy circle" and discusses how to calculate echo energy under three different states in detail. Meanwhile, an ultrasonic transmitting and receiving circuit is designed to convert the echo energy inside the energy circle into its equivalent electric power. Secondly, in order to find the two critical states of the energy circle in the process of liquid level detection, a program is designed to help with calculating two critical positions automatically. Finally, the proposed method is evaluated through a series of experiments, and the experimental results indicate that the proposed method is effective and accurate in calibration of the liquid level outside a sealed metal container.