Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both phot...
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Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both photoplethysmographic (PPG) and radial pulses with gestational age during normal pregnancy. PPG and radial pulses were simultaneously recorded from 130 healthy pregnant women at seven gestational time points. After normalizing the arterial pulse waveforms, the abscissa of notch point, the total pulse area and the reflection index were extracted and compared between different measurement points and between the PPG and radial pulses using post-hoc multiple comparisons with Bonferrioni correction. The results showed that the effect of gestational age on all the three waveform characteristics was significant (all p < 0.001) after adjusting for maternal age, heart rate and blood pressures. All the three waveform characteristics demonstrated similar changing trends with gestational age, and they were all significantly different between the measurements from gestational week 12-15 and the others (all p < 0.05, except for the PPG total pulse area between the first and second measurement points). In conclusion, this study has comprehensively quantified similar changes of both PPG and radial pulse waveform characteristics with gestational age.
A novel storage and extraction method was developed for biofluids. Plasma spiked with four types of minor ginsenosides (Rg(2), Rg(3), Rh-1 and Rh-2) was used as a model biofluid to evaluate this method. The method was...
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A novel storage and extraction method was developed for biofluids. Plasma spiked with four types of minor ginsenosides (Rg(2), Rg(3), Rh-1 and Rh-2) was used as a model biofluid to evaluate this method. The method was based on solid-phase adsorption and ultrasonic-assisted nebulization coupled with solid phase extraction (SPA-UANE-SPE). Diatomaceous earth was used as an adsorbent to store the plasma for long periods of time at room temperature. Ultrasonic-assisted nebulization system-solid phase extraction was used to extract the four minor ginsenosides from the plasma. Some experimental parameters, such as the type and amount of the adsorbent, the ultrasonic-assisted nebulization extraction time, the pH of the extraction solution, the concentration of ZnSO4, the amount of C-18, and the type and volume of the eluent were investigated and optimized. Under the optimized conditions, the recoveries of four minor ginsenosides were in the range of 78.5-91.4%, and the RSDs are in the range of 3.5-4.4%. For the storage stability test, the stability of the method was better than that of 4 degrees C storage and was similar to that of -20 degrees C storage. Compared with other methods, the proposed method had a better extraction performance and was advantageous in terms of ease of operation, stable long term storage, and minimal requirements for storage conditions. Thus, this method may be effective for sample preparation in biofluid analysis.
The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference fram...
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The drag-free satellites are widely used in the field of fundamental science as they enable the high-precision measurement in pure gravity fields. This paper investigates the estimation of local orbital reference frame(LORF) for drag-free satellites. An approach, taking account of the combination of the minimum estimation error and power spectral density(PSD) constraint in frequency domain, is proposed. Firstly, the relationship between eigenvalues of estimator and transfer function is built to analyze the suppression and amplification effect on input signals and obtain the eigenvalue range. Secondly, an optimization model for state estimator design with minimum estimation error in time domain and PSD constraint in frequency domain is established. It is solved by the sequential quadratic programming(SQP) algorithm. Finally, the orbital reference frame estimation of low-earth-orbit satellite is taken as an example, and the estimator of minimum variance with PSD constraint is designed and analyzed using the method proposed in this paper.
Polymethyl methacrylate (PMMA)-augmented cannulated pedicle-screw fixation has been routinely performed for the surgical treatment of lumbar degenerative diseases. Despite its satisfactory clinical outcomes and preval...
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Polymethyl methacrylate (PMMA)-augmented cannulated pedicle-screw fixation has been routinely performed for the surgical treatment of lumbar degenerative diseases. Despite its satisfactory clinical outcomes and prevalence, problems and complications associated with high-strength, stiff, and nondegradable PMMA have largely hindered the long-term efficacy and safety of pedicle-screw fixation in osteoporotic patients. To meet the unmet need for better bone cement for cannulated pedicle-screw fixation, a new injectable and biodegradable nanocomposite that was the first of its kind was designed and developed in the present study. The calcium phosphate-based nanocomposite (CPN) exhibited better anti-pullout ability and similar fluidity and dispersing ability compared to clinically used PMMA, and outperformed conventional calcium phosphate cement (CPC) in all types of mechanical properties, injectability, and biodegradability. In term of axial pullout strength, the CPN-augmented cannulated screw reached the highest force of similar to 120 N, which was higher than that of PMMA (similar to 100 N) and CPC (similar to 95 N). The compressive strength of the CPN (50 MPa) was three times that of CPC, and the injectability of the CPN reached 95%. In vivo tests on rat femur revealed explicit biodegradation of the CPN and subsequent bone ingrowth after 8 weeks. The promising results for the CPN clearly suggest its potential for replacing PMMA in the application of cannulated pedicle-screw fixation and its worth of further study and development for clinical uses.
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