Search Results (219)

Diabetes-related pathophysiological processes contribute to endothelial dysfunction, arterial stiffening (AS), hypertension, vascular remodeling, and impaired myocardial perfusion. This study aimed to assess the relationship between arterial wall parameters and sST2 concentration as potential risk factors in type 2 diabetes (T2DM) and investigate sex-related differences. To achieve this, we enrolled 100 patients with suspected or exacerbated coronary artery disease (CAD) and divided them into a T2DM group (n = 58) and a control group (n = 42). Endothelial reactivity (lnRHI), ABI, sST2 levels, and carotid–femoral (cfPWV) and carotid–radial pulse wave velocity (crPWV) were assessed. Coronary angiography was performed in every patient, and epicardial flow and myocardial perfusion were evaluated using QuBE and FLASH. Our results showed that the coronary angiographic findings were similar in both groups. However, T2DM patients had a significantly higher central AS (cfPWV 10.8 ± 2 vs. 9.9 ± 2.7 m/s, p < 0.05) and vascular age (70.0 ± 12.3 vs. 61.3 ± 15.4 years, p < 0.05), while peripheral AS, RHI, and ABI showed no differences. CfPWV correlated with renal function; higher HbA1c and sST2 levels were additionally associated with advanced vascular age. Notably, central AS and vascular age were higher in men with T2DM but not in women. These findings indicate that T2DM patients exhibit increased central AS and vascular aging, influenced by sST2 levels, suggesting fibrosis as a target for precision medicine in T2DM. Full article

Defensive pessimism, an important emotion regulation and motivation strategy, has increasingly attracted scholarly attention in psychology. Recently, sensor-based methods have begun to supplement or replace traditional questionnaire surveys in personality research. However, current approaches for collecting vital signs data face several challenges, including limited monitoring durations, significant data deviations, and susceptibility to external interference. This paper proposes a novel approach using a NiCr/NiSi alloy film temperature sensor, which has a K-type structure and flexible piezoelectric pressure sensor to identify and predict defensive pessimism personality traits. Experimental results indicate that the Seebeck coefficients for K-, T-, and E-type thermocouples are approximately 41 μV/°C, 39 μV/°C, and 57 μV/°C, respectively, which align closely with national standards and exhibit good consistency across multiple experimental groups. Moreover, radial artery frequency experiments demonstrate a strong linear relationship between pulse rate and the intensity of external stimuli, where stronger stimuli correspond to faster pulse rates. Simulation experiments further reveal a high correlation between radial artery pulse frequency and skin temperature, and a regression model based on the physiological sensor data shows a good fit (p < 0.05). These findings verify the feasibility of using temperature and flexible piezoelectric pressure sensors to identify and predict defensive pessimism personality characteristics. Full article

Quantum memory is essential for the prolonged storage and retrieval of quantum information. Nevertheless, no current studies have focused on the creation of effective quantum memory for continuous variables while accounting for the decoherence rate. This work presents an effective continuous-variable quantum key distribution method with parameter optimization utilizing the Elitist Elk Herd Random Immigrants Optimizer (2E-HRIO) technique. At the outset of transmission, the quantum device undergoes initialization and authentication via Compressed Hash-based Message Authentication Code with Encoded Post-Quantum Hash (CHMAC-EPQH). The settings are subsequently optimized from the authenticated device via 2E-HRIO, which mitigates the effects of decoherence by adaptively tuning system parameters. Subsequently, quantum bits are produced from the verified device, and pilot insertion is executed within the quantum bits. The pilot-inserted signal is thereafter subjected to pulse shaping using a Gaussian filter. The pulse-shaped signal undergoes modulation. Authenticated post-modulation, the prediction of link failure is conducted through an authenticated channel using Radial Density-Based Spatial Clustering of Applications with Noise. Subsequently, transmission occurs via a non-failure connection. The receiver performs channel equalization on the received signal with Recursive Regularized Least Mean Squares. Subsequently, a dataset for side-channel attack authentication is gathered and preprocessed, followed by feature extraction and classification using Adaptive Depthwise Separable Convolutional Neural Networks (ADS-CNNs), which enhances security against side-channel attacks. The quantum state is evaluated based on the signal received, and raw data are collected. Thereafter, a connection is established between the transmitter and receiver. Both the transmitter and receiver perform the scanning process. Thereafter, the calculation and correction of the error rate are performed based on the sifting results. Ultimately, privacy amplification and key authentication are performed using the repaired key via B-CHMAC-EPQH. The proposed system demonstrated improved resistance to decoherence and side-channel attacks, while achieving a reconciliation efficiency above 90% and increased key generation rate. Full article

Objectives: We aimed to quantify the damage burden measured using the Damage Index for Antiphospholipid Syndrome (DIAPS) in patients with antiphospholipid syndrome (APS) and identify patients with high damage as well as any correlations of damage with subclinical atherosclerosis. Methods: Patient damage was assessed via DIAPS. Based on demographic, clinical and laboratory characteristics, patients were divided into two subgroups: thrombotic APS patients with high vs. low damage, and non-thrombotic aPL-positive patients with vs. without damage. Participants underwent carotid/femoral ultrasound for atherosclerotic plaque detection and carotid–femoral and carotid-radial pulse wave velocity (PWV). Results: We included 112 patients with an APS diagnosis, 57 (50.9%) with primary APS and 55 (49.1%) with associated SLE. Cardiovascular (CVD) risk factors and complications were significantly more frequent in the thrombotic group, as well as in patients with high damage within the thrombotic group. We did not identify any risk factors for increased damage in the non-thrombotic group. Atherosclerotic plaque presence was present in 27 (24%) of the patients in this study with the same frequency in the APS and APS/SLE groups (p = 0.5446). Pulse wave velocity (PWV) was elevated in 27–32% patients according to analyzed arteries. Elevated PWV was more frequent in the APS group in comparison to APS/SLE only between carotid and radial arteries (p = 0.0012). Both atherosclerotic plaque presence and PWV did not correlate with damage severity. Conclusions: DIAPS indicates substantial damage in APS patients in our study. High organ damage mainly affected thrombotic patients and was related to CVD complications. At the same time, screening of subclinical atherosclerosis seems not to predict higher damage in APS patients. Full article

Fibrous structure is a promising building block for developing high-performance wearable piezoresistive sensors. However, the inherent non-conductivity of the fibrous polymer remains a bottleneck for highly sensitive and fast-responsive piezoresistive sensors. Herein, we reported a polyaniline/reduced graphene oxide @ polydopamine/poly (vinylidene fluoride) (PANI/rGO@PDA/PVDF) nanofiber piezoresistive sensor (PNPS) capable of versatile wearable biomonitoring. The PNPS was fabricated by integrating rGO sheets and PANI particles into a PDA-modified PVDF nanofiber network, where PDA was implemented to boost the interaction between the nanofiber networks and functional materials, PANI particles were deposited on a nanofiber substrate to construct electroactive nanofibers, and rGO sheets were utilized to interconnect nanofibers to strengthen in-plane charge carrier transport. Benefitting from the synergistic effect of multi-dimensional electroactive materials in piezoresistive membranes, the as-fabricated PNPS exhibits a high sensitivity of 13.43 kPa⁻¹ and a fast response time of 9 ms, which are significantly superior to those without an rGO sheet. Additionally, a wide pressure detection range from 0 to 30 kPa and great mechanical reliability over 12,000 cycles were attained. Furthermore, the as-prepared PNPS demonstrated the capability to detect radial arterial pulses, subtle limb motions, and diverse respiratory patterns, highlighting its potential for wearable biomonitoring and healthcare assessment. Full article

The monitoring of peripheral electrical bioimpedance (EBI) variations is a promising method that has the potential to replace invasive or burdensome techniques for cardiovascular measurements. Segmental or continuous recording of peripheral pulse waves can serve as a basis for calculating prognostic markers like pulse wave velocity (PWV) or include parameters such as pulse transit time (PTT) or pulse arrival time (PAT) for noninvasive blood pressure (BP) estimation, as well as potentially novel cardiovascular risk indicators. However, several technical, analytical, and interpretative aspects need to be resolved before the EBI method can be adopted in clinical practice. Our goal was to investigate and improve the application of EBI, executing its comparison with other cardiovascular assessment methods in patients hospitalized for coronary catheterization procedures. Methods: We analyzed data from 44 non-acute patients aged 45–74 years who were hospitalized for coronary catheterization at East Tallinn Central Hospital between 2020 and 2021. The radial EBI and electrocardiogram (ECG) were measured simultaneously with central and contralateral pressure curves. The Savitzky–Golay filter was used for signal smoothing. The Hankel matrix decomposer was applied for the extraction of cardiac waveforms from multi-component signals. After extracting the cardiac component, a period detection algorithm was applied to EBI and blood pressure curves. Results: Seven points of interest were detected on the pressure and EBI curves, and four with good representativeness were selected for further analysis. The Spearman correlation coefficient was low for all but the central and distal pressure curve systolic upstroke time points. A high positive correlation was found between PWV measured both invasively and with EBI. The median value of complimentary pulse wave velocity (CPWV), a parameter proposed in the paper, was significantly lower in patients with normal coronaries compared to patients with any stage of coronary disease. Conclusions: With regard to wearable devices, the EBI-derived PAT can serve as a substrate for PWV calculations and cardiovascular risk assessment, although these data require further confirmation. Full article

Background: The early recognition of systemic hemodynamic changes resulting from uteroplacental circulation disturbance in preeclampsia (PE) is of great importance for its appropriate treatment and prevention. The aim of the present study was to assess the hemodynamic changes during a roll-over test in healthy normotensive and preeclamptic pregnant women using applanation tonometry. Patients and methods: Healthy pregnant and PE women in their third trimester were studied. First, applanation tonometry was performed in a resting state on the right radial artery of each subject. In the second phase, the measurements were repeated in the left-lateral position and 5 min after turning each patient into a supine position (roll-over test = ROT). The systolic and diastolic central and peripheral blood pressures, pulse pressures, and augmentation index (AIx₇₅) values were registered for all phases. Results: A total of 21 PE and 14 healthy pregnant women entered this study. At rest, the PE patients had higher systolic, diastolic, and mean blood pressures; the preeclamptic patients had higher peripheral and central blood pressure and pulse pressure values compared to the healthy controls. A statistically significant difference was found between the augmentation index (AIX-75) values for the preeclamptic and healthy pregnant women (healthy pregnant: 9.0 ± 2.4 vs. preeclamptic: 18.9 ± 6.0; p = 0.019). During the ROT, no significant differences could be detected in the applanation tonometry parameters within the groups. The differences between the PE and healthy pregnant women continued to exist in the left-lateral and supine positions during the roll-over test. Conclusions: This is the first study combining a roll-over test and arterial stiffness measurements in healthy pregnant females and in those with PE. Although we can confirm that arterial stiffness measurements can be used to detect hemodynamic changes in pregnant women with PE, combining it with a roll-over test is unsuitable for improving the method’s sensitivity. Full article

This study investigates the vibrational and acoustic properties of Sitka spruce (Picea sitchensis (Bong.) Carr.) and Indian rosewood (Dalbergia latifolia Roxb.), two common musical instrument woods, at moisture contents of 2%, 7%, and 12%. The specimens with dimensions of 400mm (longitudinal) × 25 mm (radial) × 10 mm (tangential) were tested under cantilever beam conditions using non-contact magnetic field excitation to generate sinusoidal and pulse signals. Vibration data were collected via acceleration sensors and FFT analyzers. The test method was based on ASTM D6874-12 standard. Results indicate that increasing moisture content reduces acoustic vibration characteristics, with hardwoods exhibiting higher declines than softwoods. From 2% to 12% moisture content, the first-order sound radiation quality factor of Sitka spruce and Indian rosewood decreased by 15.41% and 15.57%, respectively, while the sound conversion rate declined by 41.91% and 43.21%. Increased moisture content lowers first-order and second-order resonance frequencies, amplitude ratios, dynamic elastic modulus, vibration propagation velocity, acoustic radiation quality factor, and acoustic conversion efficiency, while increasing acoustic impedance and the loss factor. With excitation frequency increases from 100 Hz to 1500 Hz, vibration propagation velocity rises slightly, while the loss factor declines. Full article

A laser-based selective wax ablation method using a 532 nm Nd:YAG laser was developed to improve the foliar uptake efficiency of agrochemicals in citrus leaves. In contrast to conventional applications that suffer major losses, our approach exposes up to 80% of the underlying epidermis (within the irradiated footprint) with no visible tissue damage, thereby substantially enhancing substance penetration. Efficacy was confirmed using two indicators: (1) A fluorescent glucose analog (2-NBDG) exhibited a radial expansion velocity reaching 0.0105 mm/min in treated areas, enabling rapid phloem transport across an 8 cm distance within just three minutes—an 11,280% improvement over untreated controls. (2) Laser-induced breakdown spectroscopy (LIBS) demonstrated a threefold increase in zinc (Zn) uptake (and over fivefold compared to untreated leaves) when using a Zn-based foliar fertilizer. To assess processing efficiency, we quantified the ablation footprint by combining single-pulse laser shots in a 1 cm-diameter region and found that 23.4% of the total area was fully exposed. This selective, non-invasive approach enables precise targeting, potentially reducing fertilizer and pesticide usage while improving crop health. Beyond citrus, it is readily adaptable to other crops, with integration into orchard or greenhouse spraying systems as a promising path for scale-up. Such versatility highlights the technique’s potential to optimize efficacy, cut input costs, and diminish environmental impact in modern precision agriculture. Full article

Fiber-optic Fabry–Pérot (F–P) sensors offer significant potential for non-invasive hemodynamic monitoring, but existing sensing systems face limitations in multi-channel measurement capabilities and dynamic demodulation accuracy. This study introduces a sparse-frequency-scanning white-light interferometry (SFS-WLI) system with an adaptive mode-locked cross-correlation (MLCC) algorithm to address these challenges. The system leverages telecom-grade semiconductor lasers (191.2–196.15 THz sweep range, 50 GHz step) and a Fibonacci-optimized MLCC algorithm to achieve real-time cavity length demodulation at 5 kHz. Compared to normal MLCC algorithm, the Fibonacci-optimized algorithm reduces the number of computational iterations by 57 times while maintaining sub-nanometer resolution under dynamic perturbations. Experimental validation demonstrated a carotid–radial pulse wave velocity of 5.12 m/s in a healthy male volunteer. This work provides a scalable and cost-effective solution for cardiovascular monitoring with potential applications in point-of-care testing (POCT) and telemedicine. Full article

Background: Cardiac amyloidosis (CA) is a progressive disorder characterized by amyloid fibril deposition in the heart, leading to heart failure and arrhythmias. Arterial stiffness, assessed by pulse wave velocity (PWV), is recognized as an adverse consequence of amyloidosis, yet its progression and relationship with myocardial dysfunction remain inadequately explored. This study examines the progression of PWV and its potential association with the deterioration of global longitudinal strain (GLS) in CA patients over a 6-month follow-up period. Methods: This prospective study enrolled 31 patients who were diagnosed with CA, including both the immunoglobulin light chain (AL) and transthyretin (ATTR) forms. All participants underwent a full echocardiographic study and PWV measurements (carotid-femoral [c-f] and carotid-radial [c-r] PWV) at baseline and 6-month follow-up. Age- and sex-matched individuals with similar cardiovascular risk factors were included as a control group. Results: In the CA group, the left ventricular mass index (LVMI) increased significantly from 119.4 ± 52.1 to 124 ± 53.2 g/m² (p = 0.002). Both c-f and c-r PWV showed significant increases at the 6-month follow-up (p < 0.001 and p = 0.005, respectively). The GLS deteriorated significantly from −14 ± 4.4% to −12.8 ± 4.9% (p = 0.018). No significant changes were observed in the control group. A weak correlation (r = 0.3; p = 0.095) was found between increases in PWV and GLS deterioration. Conclusions: Both arterial stiffness and myocardial dysfunction worsen rapidly in CA patients. However, the weak correlation between PWV and GLS suggests that they may evolve through independent mechanisms, necessitating further research to understand their complex interplay in CA. Full article

Carbon fiber resin matrix composites (CFRP) are widely recognized for their exceptional properties such as high temperature resistance and high strength, making them indispensable in aerospace, automotive, and medical applications. Despite their growing use, precision machining of CFRP remains challenging. Traditional mechanical machining methods often lead to severe tool wear, matrix damage, fiber pullout, delamination, and chipping. In contrast, nanosecond pulsed laser machining has garnered significant attention due to its high precision, minimal heat-affected zone (HAZ), and versatility in processing various materials. In this study, a finite element model was developed to account for the anisotropic heat transfer and non-homogeneous properties of CFRP, enabling accurate simulation of laser machining processes. The study analyzed the influence of laser parameters on machining quality and revealed the ablation mechanism and HAZ evolution under varying laser conditions. Notably, it was observed that the thermal conductivity along the carbon fiber’s axial direction is higher than in the radial direction, resulting in an elliptical ablation pattern after laser irradiation. Additionally, the effects of the laser power, pulse frequency, and scanning speed on the depth and width of grooves were investigated through finite element simulations and validation experiments. A heat accumulation effect between laser pulses was observed, where resin matrix material around the grooves was removed once the accumulated heat exceeded the resin’s pyrolysis temperature. In addition, if there is too much laser power or too small a laser scanning speed, the fiber will undergo severe ablation removal, which will form serious thermal damage and a heat-affected zone. Gradually increasing the laser power or decreasing the scanning speed led to deeper and wider grooves, with an inverted triangular morphology. Moreover, the selection of different parameters had a significant effect on the ablation morphology, heat-affected zone, and the contour parameters of the grooves. This research contributes to understanding the laser–CFRP interaction mechanism and offers insights for optimizing laser processing parameters to improve material processing accuracy and efficiency, further expanding the potential applications of laser technology in composite material machining. Full article

(1) The aliasing of radial velocities from weather radars is a known challenge in meteorology. It may also occur during bird migration if the unambiguous velocity threshold is below the birds’ ground speed. High variability in birds’ radial velocities and high flight speeds lead to multiple aliasing (folding) and challenge meteorological dealiasing approaches. Unfolded radial velocities are essential for calculating flight directions and speed and derived migration traffic rates for aeroecological applications. (2) We study the occurrence of aliasing in measurements of different pulse repetition frequencies (PRF) in C-band weather radars in bird and insect cases and test the efficiency of a dealiasing algorithm widely used in biological weather radar software. We use dual-PRF measurements as a reference to avoid the folding of radial velocities in quantitative and qualitative bird migration outputs. (3) The dealiasing algorithm performed poorly in single-PRF measurements during bird migration, though not in insect and precipitation cases. In contrast, dual-PRF velocities yielded proper flight speeds, flight directions and migration traffic rates. (4) The study unveils severe biases in aeroecological analyses of C-band weather radars from imperfectly dealiased single-PRF radial velocities. Dual-PRF measurements with appropriate dealiasing postprocessing offer a valid alternative to single PRF and should be preferred whenever available. Full article

This study introduces a novel application of synchrotron X-ray phase contrast imaging to investigate the internal flow dynamics and liquid jet characteristics in a direct injection gasoline nozzle. Using optimized imaging parameters, including a 19 mm insertion gap and a 0.15 ns electron pulse (16 mA), we achieved high-quality visualization of needle motion and in-nozzle flip flow. The results show that cavitation appears rapidly with increasing needle valve lift, transitioning from unstable behavior below 40 µm to stable flip flow at higher lifts. The flip flow characteristics vary between nozzle holes due to differences in inlet angles. Internal flow velocity analysis reveals significant radial and axial gradients, with initial velocity overshoot during injection start followed by stable flow. The presence of flip flow accelerates jet breakup on the flip-contact side, leading to droplet–wall interactions in the counterbore. Different nozzle geometries, particularly hole inlet angle and length-to-diameter ratio, significantly influence jet width and velocity distributions. This comprehensive approach advances our understanding of practical nozzle internal flow dynamics and provides valuable insights for optimizing fuel injection system performance in engines. Full article

To suppress the influence of aerosols scattering on the double-edge detection technique and achieve high-accuracy measurement of the wind field throughout the troposphere to the lower stratosphere, an ultraviolet 355 nm Rayleigh–Brillouin Doppler lidar technology based on a dual-pass dual Fabry–Perot interferometer (FPI) is proposed. The wind speed detection principle of this technology is analyzed, and the formulas for radial wind speed measurement error caused by random noise and wind speed measurement bias caused by Mie scattering signal contamination are derived. Based on the detection principle, the structure of the lidar system is designed. Combining the wind speed measurement error and measurement bias on both sides, the parameters of the dual-pass dual-FPI are optimized. The free spectral range (FSR) of the dual-pass dual-FPI is selected as 12 GHz, the bandwidth as 1.8 GHz, and the peak-to-peak spacing as 6 GHz. Further, the detection performance of this new type of Rayleigh–Brillouin Doppler lidar with the designed system parameters is simulated and analyzed. The simulation results show that at an altitude of 0–20 km, within the radial wind speed dynamic range of ±50 m/s, the radial wind speed measurement bias caused by aerosol scattering signal is less than 0.17 m/s in the cloudless region; within the radial wind speed dynamic range of ±30 m/s, the bias is less than 0.44 m/s and 0.91 m/s in the simulated cumulus cloud at 4 km where aerosol backscatter ratio R_β = 3.8 and cirrus cloud at 9 km where R_β = 2.9, respectively; using a laser with a pulse energy of 350 mJ and a repetition frequency of 50 Hz, a 450 mm aperture telescope, setting the detection zenith angle of 30°, vertical resolution of 26 m@0–10 km, 78 m@10–20 km, and 260 m@20–30 km, and a time resolution of 1 min, with the daytime sky background brightness taking 0.3 WSr⁻¹m⁻²nm⁻¹@355 nm, the radial wind speed measurement errors of the system during the day and night are below 2.9 m/s and 1.6 m/s, respectively, up to 30 km altitude, below 0.28 m/s at 10 km altitude, and below 0.91 m/s at 20 km altitude all day. Full article