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753 result(s) for "Zhou, Sai"
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A wearable cardiac ultrasound imager
Continuous imaging of cardiac functions is highly desirable for the assessment of long-term cardiovascular health, detection of acute cardiac dysfunction and clinical management of critically ill or surgical patients 1 – 4 . However, conventional non-invasive approaches to image the cardiac function cannot provide continuous measurements owing to device bulkiness 5 – 11 , and existing wearable cardiac devices can only capture signals on the skin 12 – 16 . Here we report a wearable ultrasonic device for continuous, real-time and direct cardiac function assessment. We introduce innovations in device design and material fabrication that improve the mechanical coupling between the device and human skin, allowing the left ventricle to be examined from different views during motion. We also develop a deep learning model that automatically extracts the left ventricular volume from the continuous image recording, yielding waveforms of key cardiac performance indices such as stroke volume, cardiac output and ejection fraction. This technology enables dynamic wearable monitoring of cardiac performance with substantially improved accuracy in various environments. Innovations in device design, material fabrication and deep learning are described, leading to a wearable ultrasound transducer capable of dynamic cardiac imaging in various environments and under different conditions.
A fully integrated wearable ultrasound system to monitor deep tissues in moving subjects
Recent advances in wearable ultrasound technologies have demonstrated the potential for hands-free data acquisition, but technical barriers remain as these probes require wire connections, can lose track of moving targets and create data-interpretation challenges. Here we report a fully integrated autonomous wearable ultrasonic-system-on-patch (USoP). A miniaturized flexible control circuit is designed to interface with an ultrasound transducer array for signal pre-conditioning and wireless data communication. Machine learning is used to track moving tissue targets and assist the data interpretation. We demonstrate that the USoP allows continuous tracking of physiological signals from tissues as deep as 164 mm. On mobile subjects, the USoP can continuously monitor physiological signals, including central blood pressure, heart rate and cardiac output, for as long as 12 h. This result enables continuous autonomous surveillance of deep tissue signals toward the internet-of-medical-things. A wearable ultrasound patch monitors subjects in motion using machine learning and wireless electronics.
A photoacoustic patch for three-dimensional imaging of hemoglobin and core temperature
Electronic patches, based on various mechanisms, allow continuous and noninvasive monitoring of biomolecules on the skin surface. However, to date, such devices are unable to sense biomolecules in deep tissues, which have a stronger and faster correlation with the human physiological status than those on the skin surface. Here, we demonstrate a photoacoustic patch for three-dimensional (3D) mapping of hemoglobin in deep tissues. This photoacoustic patch integrates an array of ultrasonic transducers and vertical-cavity surface-emitting laser (VCSEL) diodes on a common soft substrate. The high-power VCSEL diodes can generate laser pulses that penetrate >2 cm into biological tissues and activate hemoglobin molecules to generate acoustic waves, which can be collected by the transducers for 3D imaging of the hemoglobin with a high spatial resolution. Additionally, the photoacoustic signal amplitude and temperature have a linear relationship, which allows 3D mapping of core temperatures with high accuracy and fast response. With access to biomolecules in deep tissues, this technology adds unprecedented capabilities to wearable electronics and thus holds significant implications for various applications in both basic research and clinical practice. The authors present a wearable photoacoustic patch, which integrates laser diodes and piezoelectric transducers for three-dimensional imaging of hemoglobin and temperature in deep tissues.
Association between smoking and postoperative delirium in surgical patients with pulmonary hypertension: a secondary analysis of a cohort study
Background Previous studies have declared that smoking was a risk factor for postoperative delirium (POD), but others have inconsistent results. Up till now, the association between smoking and POD has not been verified. This study investigates the relationship between smoking and POD in patients with pulmonary hypertension (PHTN) in the United States. Methods Patients with PHTN who underwent non-cardiac, non-obstetric surgery were enrolled in the original research completed by Aalap C. et al. We further excluded the patients undergoing intracranial surgery and the patients with sepsis and perioperative stroke to avoid interference with POD assessment. The generalized linear model and generalized additive model were used to explore the relationship between smoking and POD. The propensity score adjustment was used for sensitivity analyses. Results Five hundred thirty-nine patients were included in this study. The overall incidence of POD was 3.0% (16/539). After adjusting the potential confounders (age, systemic hypertension, coronary artery disease, COPD, length of surgery, intrathoracic surgery, vascular surgery), a positive relationship was found between smoking status and POD (OR = 4.53, 95% CI: 1.22 to 16.86, P  = 0.0243). In addition, the curvilinear relationship between smoking burden (pack-years) and POD is close to a linear relationship. Conclusion Smoking probably shows a positive correlation with POD in patients with PHTN.
Sleeve Gastrectomy Improves Hepatic Glucose Metabolism by Downregulating FBXO2 and Activating the PI3K-AKT Pathway
Type 2 diabetes mellitus (T2DM), a chronic metabolic disease, is a public health concern that seriously endangers human health. Sleeve gastrectomy (SG) can relieve T2DM by improving glucose homeostasis and enhancing insulin sensitivity. However, its specific underlying mechanism remains elusive. SG and sham surgery were performed on mice fed a high-fat diet (HFD) for 16 weeks. Lipid metabolism was evaluated via histology and serum lipid analysis. Glucose metabolism was evaluated using the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). Compared with the sham group, the SG group displayed a reduction in liver lipid accumulation and glucose intolerance, and western blot analysis revealed that the AMPK and PI3K-AKT pathways were activated. Furthermore, transcription and translation levels of FBXO2 were reduced after SG. After liver-specific overexpression of FBXO2, the improvement in glucose metabolism observed following SG was blunted; however, the remission of fatty liver was not influenced by the over expression of FBXO2. Our study explores the mechanism of SG in relieving T2DM, indicating that FBXO2 is a noninvasive therapeutic target that warrants further investigation.
Canagliflozin alleviates high glucose-induced peritoneal fibrosis via HIF-1α inhibition
The cardioprotective effects of sodium-glucose cotransporter type 2 (SGLT2) inhibitors have been demonstrated in many studies. However, their benefits for end-stage kidney disease patients, particularly those on peritoneal dialysis, remain unclear. SGLT2 inhibition has shown peritoneal protective effects in some studies, but the mechanisms are still unknown. Herein, we investigated the peritoneal protective mechanisms of Canagliflozin in vitro by simulating hypoxia with CoCl 2 in human peritoneal mesothelial cells (HPMCs) and rats by intraperitoneal injection of 4.25% peritoneal dialysate simulating chronic high glucose exposure. CoCl 2 hypoxic intervention significantly increased HIF-1α abundance in HPMCs, activated TGF-β/p-Smad3 signaling, and promoted the production of fibrotic proteins (Fibronectin, COL1A2, and α-SMA). Meanwhile, Canagliflozin significantly improved the hypoxia of HPMCs, decreased HIF-1α abundance, inhibited TGF-β/p-Smad3 signaling, and decreased the expression of fibrotic proteins. Five-week intraperitoneal injection of 4.25% peritoneal dialysate remarkably increased peritoneal HIF-1α/TGF-β/p-Smad3 signaling and promoted peritoneal fibrosis and peritoneal thickening. At the same time, Canagliflozin significantly inhibited the HIF-1α/TGF-β/p-Smad3 signaling, prevented peritoneal fibrosis and peritoneal thickening, and improved peritoneal transportation and ultrafiltration. High glucose peritoneal dialysate increased the expression of peritoneal GLUT1, GLUT3 and SGLT2, all of which were inhibited by Canagliflozin. In conclusion, we showed that Canagliflozin could improve peritoneal fibrosis and function by ameliorating peritoneal hypoxia and inhibiting the HIF-1α/TGF-β/p-Smad3 signaling pathway, providing theoretical support for the clinical use of SGLT2 inhibitors in patients on peritoneal dialysis.
Identification and manipulation of spin wave polarizations in perpendicularly magnetized synthetic antiferromagnets
Interlayer exchange-coupled synthetic antiferromagnets (SAFs) have the combined advantages of both high frequency of antiferromagnets and easy detection of ferromagnets. Here, magnetic excitations are investigated by theoretical analysis and micromagnetic simulations in SAFs that consist of two identical ferromagnetic layers with perpendicular magnetic anisotropy. Different from the common in-phase acoustic mode and out-of-phase optic mode, linearly or circularly polarized spin wave modes can be excited at zero bias field by using different types of microwave magnetic fields. Once a bias magnetic field is applied along the easy-axis, left-handed (LH) and right-handed (RH) polarization modes are observed, and the resonance frequency of RH (LH) mode of the SAFs increases (decreases) linearly with the increase of bias magnetic fields until a critical spin-flop field is reached, which is in accordance with collinear antiferromagnets with easy-axis anisotropy. These simulation results agree with the theoretical derivation and provide fundamental insight into the nature of dynamic properties of the perpendicularly magnetized SAFs, which may provide new prospects for spintronic applications.
Developmentally regulated internal transcription initiation during meiosis in budding yeast
Sporulation of budding yeast is a developmental process in which cells undergo meiosis to generate stress-resistant progeny. The dynamic nature of the budding yeast meiotic transcriptome has been well established by a number of genome-wide studies. Here we develop an analysis pipeline to systematically identify novel transcription start sites that reside internal to a gene. Application of this pipeline to data from a synchronized meiotic time course reveals over 40 genes that display specific internal initiations in mid-sporulation. Consistent with the time of induction, motif analysis on upstream sequences of these internal transcription start sites reveals a significant enrichment for the binding site of Ndt80, the transcriptional activator of middle sporulation genes. Further examination of one gene, MRK1, demonstrates the Ndt80 binding site is necessary for internal initiation and results in the expression of an N-terminally truncated protein isoform. When the MRK1 paralog RIM11 is downregulated, the MRK1 internal transcript promotes efficient sporulation, indicating functional significance of the internal initiation. Our findings suggest internal transcriptional initiation to be a dynamic, regulated process with potential functional impacts on development.
Simulation Study on Solar Single/Double-Effect Switching LiBr-H2O Absorption Refrigeration System
In this study, a solar single/double-effect switching LiBr-H2O absorption refrigeration system was investigated to make full use of solar energy and give full play to the advantages of solar refrigeration systems. A corresponding thermodynamic dynamic mathematical model was developed. The operation characteristics of the system operating continuously for one week were analyzed. In order to highlight the advantages of the solar single/double-effect switching absorption refrigeration system, it was compared with other forms of solar refrigeration systems and compression refrigeration systems. The practical application potential of the single/double-effect switching LiBr-H2O absorption refrigeration system was evaluated from the perspective of economy and environmental effect. The results showed that the system could achieve the switching operation between single-effect mode and double-effect mode under weather conditions of high solar radiation intensity, and the daily cooling efficiency on such days was relatively high. After an auxiliary heater was added, the primary energy savings of the solar single/double-effect switching LiBr-H2O absorption refrigeration system were 25–52%, depending on the area of the collector and the volume of the storage tank. The solar fraction of the system was about 71.99% for continuous operation during the whole refrigeration season. However, the initial investment cost of the system equipment accounted for 89.66% of the total cost. Compared with the traditional compression refrigeration system, the initial investment cost of the solar single/double-effect switching LiBr-H2O absorption refrigeration system was higher, but it had a better environmental protection effect.
Experimental and Numerical Study of the Heat Dissipation of the Electronic Module in an Air Conditioner Outdoor Unit
Effective thermal management of electronic modules is crucial to the reliable operation of variable frequency air conditioners. For this reason, two types of plate-finned heat sinks of electronic modules were selected. The experiments utilized ceramic heating plates to simulate chip heating, conducted in an enthalpy difference laboratory with controlled environments. Four installation cases were analyzed to evaluate the impact of heat sink orientation, airflow direction, and structural layout. The results showed that when multiple chips were arranged on the same heat dissipation substrate, the heat dissipation process of the chips would be coupled with each other, and the rational layout of the chips played an important role in heat dissipation. In the case of cooling air impacting the jet, the heat dissipation performance of the heat sink was significantly improved, and the heat transfer coefficient of the heat sink was as high as 316.5 W·m−2·°C−1, representing a 6.9% improvement over conventional designs (case I: 296.1 W·m⁻2·°C⁻1). The maximum temperature of the chips could be reduced by 11.1%, which is 10.1 °C lower. This study will provide a reference for the optimization design of the heat sink of the electric control module in inverter air conditioners.