Traditional radio frequency filters cannot meet the demands of miniaturization, high frequency operation, integration, and broadband capacity in new-generation communication system owing to their larger volumes. A thin film bulk acoustic resonator (FBAR) is therefore suggested as an optimum solution because of its small volume and a good performance. In this study, the COMSOL multiphysics software was used to build 2 D and 3 D finite element models to analyze the harmonic characteristics of the FBAR. Based on the optimized structural parameters, the FBAR was fabricated with series resonant frequency, parallel resonant frequency, and effective coupling coefficient values of 3.705, and 3.82 GHz, and 7.4%, respectively. Compared with the simulated FBAR results, the effective coupling coefficient of the fabricated FBAR declined by only 0.1%, almost achieving the desired performance.
Background
The effect of hepatitis B virus (HBV) replication during pregnancy on the outcomes of singleton pregnancies is not fully understood. In this study, we investigated the association between HBV replication and poor maternal and infant outcomes.
Methods
We retrospectively analyzed the clinical data of 836 pregnant inpatients with hepatitis B surface antigen positivity who delivered at two provincial tertiary grade A hospitals in Fujian Province from June 2016 to October 2020. The patients were divided into the HBV replication (n = 283) and non-HBV replication groups (n = 553). Chi-squared test of adverse maternal and infant outcomes was performed using SPSS 26.0 software, and univariate analysis of variance of basic clinical indexes of pregnant women and newborns was performed. P<0.05 was considered statistically significant.
Results
The incidences of perinatal outcomes of intrahepatic cholestasis of pregnancy, hypertensive syndrome complicating pregnancy, gestational diabetes mellitus, preterm birth, macrosomia, growth restriction, and vaginal infection in the HBV and non-HBV replication groups were not significantly different (P>0.05); however, there were significant differences between the two groups in the rate of cesarean section (53.8% vs. 45.0%; P=0.017) and neonatal jaundice (15.5% vs. 7.2%; P=0.000). After using propensity score analysis and multivariable modeling to adjust for glutamic pyruvic transaminase and glutamic oxaloacetic transaminase levels in the two groups, the replication group was found to have an increased risk for cesarean section (54.3% vs. 33.5%; P=0.000) and vaginal infection (3% vs. 0.4%; P=0.038), and their infants had a higher rate of newborn jaundice (16% vs.1.5%; P=0.000).
Conclusion
The findings provide further understanding of the association between maternal HBV replication status and perinatal outcomes. Pregnant women with viral replication have an increased risk of vaginal infection and cesarean section, and their infants appear to be at a higher risk for neonatal jaundice.
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