Novel transcatheter aortic heart valves exhibiting excellent hemodynamic performance and low-fouling property

Transcatheter aortic heart valves (TAHVs) have been widely used for aortic valve replacements, with less trauma and lower clinical risk compared with traditional surgical heart valve replacements. In the present study, composites of poly(ethylene glycol) diacrylate (PEGDA) hydrogels and anisotropic high-shrinkage polyethylene terephthalate/polyamide6 (PET-PA6) fabric (PEGDA/PET-PA6) were fabricated as artificial heart valve leaflets. Dynamic mechanical analyses (DMA) indicated that PEGDA/PET-PA6 composites possessed anisotropic mechanical properties (i.e., storage moduli ～23.30 ± 1.36 MPa parallel to the aligned fabric fibers and ～9.68 ± 0.90 MPa perpendicular to the aligned fibers at 1 Hz) that were comparable to aortic valve leaflets. The PEGDA/PET-PA6 composites with smooth surfaces were highly hydrophilic (contact angle ～41.6° ± 3.8°) and had low-fouling properties without platelet adhesion, suggesting a low risk of thrombogenicity when they interacted with blood. Furthermore, transcatheter aortic heart valves were fabricated using nitinol self-expanding frames and PEGDA/PET-PA6 composites as artificial leaflets, which presented excellent hemodynamic performance with a large orifice area (1.75 cm²) and low regurgitation (3.41%), thus meeting the requirements of ISO 5840-3 standard. Therefore, PEGDA/PET-PA6 composites had suitable mechanical properties, good biocompatibility, and low-fouling properties, indicating that they might be used for TAHVs in the future.     

Non-Contact Physiological Measurement System for Wearing Masks During the Epidemic

Physiological signals indicate a person’s physical and mental state at any given time. Accordingly, many studies extract physiological signals from the human body with non-contact methods, and most of them require facial feature points. However, under COVID-19, wearing a mask has become a must in many places, so how non-contact physiological information measurements can still be performed correctly even when a mask covers the facial information has become a focus of research. In this study, RGB and thermal infrared cameras were used to execute non-contact physiological information measurement systems for heart rate, blood pressure, respiratory rate, and forehead temperature for people wearing masks due to the pandemic. Using the green (G) minus red (R) signal in the RGB image, the region of interest (ROI) is established in the forehead and nose bridge regions. The photoplethysmography (PPG) waveforms of the two regions are obtained after the acquired PPG signal is subjected to the optical flow method, baseline drift calibration, normalization, and bandpass filtering. The relevant parameters in Deep Neural Networks (DNN) for the regression model can correctly predict the heartbeat and blood pressure. In addition, the temperature change in the ROI of the mask after thermal image processing and filtering can be used to correctly determine the number of breaths. Meanwhile, the thermal image can be used to read the temperature average of the ROI of the forehead, and the forehead temperature can be obtained smoothly. The experimental results show that the above-mentioned physiological signals of a subject can be obtained in 6-s images with the error for both heart rate and blood pressure within 2%~3% and the error of forehead temperature within ±0.5°C.     

Contribution of various substrates to total citric acid cycle flux and ]anaplerosis as determined by13C isotopomer analysis and O2 consumption in the heart

A simple relationship between parameters derived from a¹³C NMR isotopomer analysis and O₂ consumption is presented that allows measurement of the absolute rate of acetyl-CoA oxidation and anaplerotic flux in tissues oxidizing a mixture of four substrates. The method was first applied in a study of the effects of work state and -adrenergic stimulation on net acetate oxidation and anaplerosis in the isolated working rat heart. The results demonstrate that the anticipated ratio of 2 between O₂ consumption and TCA cycle flux for hearts oxidizing only acetate holds at low workload when anaplerosis is low, but deviates toward a factor of 3 under high workload conditions when anaplerosis is increased. This analysis was also extended to hearts that oxidize a more physiological mixture of substrates including long-chain fatty acids, acetoacetate, lactate, pyruvate, and glucose. We show that the contribution each substrate makes to total TCA cycle flux can be determined by combined¹³C NMR and O₂ consumption measurements. The present study also demonstrates that stimulation of anaplerosis (by addition of propionate) can significantly alter the relative contribution each substrate makes to total TCA cycle flux. We conclude that if¹³C labeling patterns are selected appropriately, a comprehensive picture of flux through all major metabolic pathways feeding the cycle can be determined in a single experiment even when complex physiological mixtures of substrates are provided.     

3σ规则和μ律阈值法在心音信号去噪中的应用

讨论小波包阈值法去噪的机理,提出基于小波包变换的3σ规则和μ律阈值法在心音信号预处理中的方法,该方法保留小波包变换去噪的优势,能够有效地突出心音的特征部分,在心杂音信号去噪中有较好的效果。实验结果表明,该方法在去除干扰和心杂音上有着一定的优势,在心音信号检测中有重要的应用价值。     

3σ规则和µ律阈值法在心音信号去噪中的应用

讨论小波包阈值法去噪的机理,提出基于小波包变换的3σ规则和µ律阈值法在心音信号预处理中的方法,该方法保留小波包变换去噪的优势,能够有效地突出心音的特征部分,在心杂音信号去噪中有较好的效果。实验结果表明,该方法在去除干扰和心杂音上有着一定的优势,在心音信号检测中有重要的应用价值。     

Interactive Fibre Structure Visualization of the Heart

The heart consists of densely packed muscle fibres. The orientation of these fibres can be acquired by using Diffusion Tensor Imaging (DTI) ex vivo. A good way to visualize the fibre structure in a cross section of the heart is by showing short line segments originating from the cross section and aligned with the local direction of the fibres. If the line segments are placed dense enough, one can see how the fibre orientations change. However, generation of the line segments takes time and thus the user has to wait for new geometry to be generated when the plane defining the cross section is changed. We present a new direct rendering method for the visualization of the 3D vector field in a 2D user‐definable cross section of a heart. On the intersection of the plane with the vector field, the full 3D vectors are rendered as 3D line segments with a local ray casting approach. No preprocessing of the data is needed and no geometry is generated. This technique allows a fast inspection of the data to identify interesting areas where further analysis is necessary (e.g. quantification or generation of streamlines). We also show how the technique is generalized to other glyph shapes than line segments by implementing ellipsoids.     

驾驶员疲劳状态生理信号的DFA

通过去趋势波动分析(DFA)研究驾驶员疲劳状态的心率变异性信号和脑电信号特征.22名被试在驾驶模拟器上进行模拟驾驶作业,采集驾驶过程中的心率变异性和脑电信号并进行离线分析.Wil-coxon符号秩检验用于分析清醒和疲劳两种状态间DFA标度指数的差异,受试者工作曲线(ROC)分析用于确定DFA区分疲劳驾驶和清醒驾驶的能力.结果表明:疲劳状态时,心率变异性和脑电信号的标度指数显著增加(Wilcoxon符号秩检验,p＜0.01);心率变异性和脑电信号标度指数的ROC下面积最大分别为0.75和0.78.DFA的标度指数具有应用于驾驶疲劳监测系统的前景.     

基于 LabVIEW2011 对心音信号 CWT 滤波的实现

目的：为除去杂波,同时克服sn叮对分辨率的限制,提高心音分析的准确性和实时性。方法：引入CWT滤波的理论,基于该理论构造算法,利用LabVIEW2011编程在应用上进行实现。结果：利用CWT滤波的方法成功对杂波滤除。结论：采用上述方法能够实现对于心音信号优化处理。     

有限元在心脏瓣膜支架设计中的应用

通过SolidWorks建立某心脏瓣膜支架的三维模型,用Abaqus对瓣膜支架压握入鞘过程与疲劳情况进行分析,得到支架的应变分布和疲劳性能.结果可以判断支架设计的优劣,为支架优化设计提供参考.     

一种新型的科学健身训练仪的设计

随着科技技术的发展,人们的体力劳动越来越多的被现代化技术装置所取代,造成劳动者得了很多现代文明病。人们意识到健身运动的重要性。但不是任何形式、任何强度的运动都能达到健身的目的。针对这一问题设计了一种科学健身训练仪,通过监测人的心率和血氧饱和度,通过心率和血氧同运动强度的关系指导人们进行最佳健身训练,对过度运动预警,同时还具备了对运动效果评估的功能。系统电路具有小型化,模块化,低功耗的特点,较适合家庭健身训练时使用。