ABSTRACT
Objective To develop a high-performance liquid chromatography-diode array detector (HPLC-DAD) method for determination of cinnamic acid in the decoction of cinnamon, and investigate the effect of different storage temperature and time for the stability of cinnamic acid. Methods An HPLC- DAD method was established. Separation was performed on an Agilent Zorbax C18 column (4.6 mm×250 mm, 5 μm) with 0.1% formic-acetonitrile acid water solution (60:40) as the mobile phase by isocratic elution. The flow rate was 1.0 ml/min, the temperature of column was 25 ℃, the injection volume was 5 μl, the detective UV wave length was 275 nm. The decoction were stored under refrigerated temperature (4 ℃) ambient temperature (25 ℃) and high temperature (40 ℃). The cinnamic acid was detected after 0, 1, 3, 7, 14, 21, 30 d. Results Cinnamic acid was successfully separated by this method, with good linear relationship between 10.21-204.20 μg/ml. The precision, repeatability, stability and recovery were good. Compared with the zero day, the content of cinnamic acid in the decoction of cinnamon decreased significantly (P<0.01) after 21 days and 30 days of ambient temperature storage and after 14 days, 21 days and 30 days of high temperature storage, but no significant change was found in the other groups (P>0.05). Conclusion This HPLC-DAD method had good stability and repeatability. Cinnamic acid was stable in the decoction of cinnamon for 30 days under refrigerated temperature.
ABSTRACT
The ultrasound Doppler fetal heart rate measurement is the gold standard of fetal heart rate counting. However, the existing fetal heart rate extraction algorithms are not designed specifically to suppress the high maternal interference during the second stage of labor, and false detection occurrences are common during labor. With this background, a method combining time-frequency frame template library optimal selecting and non-linear template matching is proposed. The method contributes a template library, and the optimal template can be selected to match the signal frame. After the short-time Fourier transform of the signal, the difference between the signal and the template is optimized by leaky rectified linear unit (LReLU) function frame by frame. The heart rate was calculated from the peak of the matching curve and the heart rate was calculated. By comparing the proposed method with the autocorrelation method, the results show that the detection accuracy of the proposed method is improved by 20% on average, and the non-linear template matching of 23% samples is at least 50% higher than the autocorrelation method. This paper designs the algorithm by analyzing the characteristics of the interference and signal mixing. We hope that this paper will provide a new idea for fetal heart rate extraction which not only focuses on the original signal.
Subject(s)
Female , Humans , Pregnancy , Algorithms , Fetal Monitoring , Fourier Analysis , Heart Rate, Fetal , Signal Processing, Computer-Assisted , Ultrasonography, DopplerABSTRACT
The existing fetal monitor is prone to false detection in the case of high maternal interference in the second stage of labor. With this background, the article designs and implements a combined maternal-fetal fetal heart monitoring system. The system obtains the Doppler signal of the abdominal fetal heart and the blood oxygen signal of the mother's finger, and estimates the maternal interference degree in the fetal heart rate Doppler signal according to the maximum correlation value between the maternal finger blood oxygen signal and the abdominal fetal heart Doppler signal, and switches the fetal heart rate extraction algorithm between the autocorrelation method suitable for lower interference and improved template method suitable for higher interference according to the maternal interference degree. The accuracy of our method is 9.2% which is higher than that of the improved template matching method and 6.1% higher than that of the autocorrelation method.