Search Results (103)

Background/Objectives: Adaptation to extrauterine life is challenging for preterm newborns. Environmental stimuli, such as noise, can lead to adverse health outcomes, causing instability of vital parameters and impairment of neurodevelopment. The American Academy of Pediatrics recommends a maximum environmental noise level of 45 decibels (dB) or less in the NICU. The study’s primary aim was to describe environmental noise in a neonatal intensive care unit and to analyze potential associations between noise and vital parameters of preterm newborns, including heart rate, respiratory rate, and oxygen saturation levels. Methods: A pilot observational feasibility study was conducted in a level III NICU. Sound levels and vital parameters were recorded over four hours for each preterm newborn. Confounding variables were controlled. Data were analyzed using descriptive statistics, Kendall’s τ-b, and logistic regression analysis. Ethical approval and parental consent were obtained. Results: The average environmental noise level was consistently above 45 dB. Six patients were enrolled, and 22 recordings (ranging in length from 1 to 4 h) were performed. Data adjusted for confounding variables show a statistically significant Kendall’s correlation between heart rate and decibels (τ-b = 0.89, p = 0.003, n = 520), suggesting a monotonous crescent tendency between these two variables, although the relationship is not strong. The logistic regression model indicates that the odds ratio (OR) for decibels related to tachycardia is 1.066, meaning that for each 1 dB increase, the probability of tachycardia rises by 6.6% (p < 0.001). Conversely, the OR for respiratory rate is 0.959, suggesting that for each unit increase in respiratory rate, the probability of tachycardia decreases by approximately 4.1% (p < 0.001). Conclusions: The study reveals that the mean environmental noise level in the NICU consistently exceeds the recommended safety level. Decibels are one of the significant variables contributing to the likelihood of tachycardia, and an increase in decibels has a significant effect on this, but it is not the only one. Further analysis of a larger sample is needed. Full article

Background/Objectives: Insulin resistance is a key factor in the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD), but accurately measuring it in patients with type 2 diabetes (T2D) remains challenging. This study examines the relationship between a recently proposed insulin resistance index and the presence of liver steatosis and fibrosis in individuals with T2D. Methods: This cross-sectional study utilized data from the 2017–2020 National Health and Nutrition Examination Survey. Patients with T2D who did not have chronic viral hepatitis or significant alcohol intake were included. The insulin sensitivity (IS) index was calculated using a formula incorporating body mass index, urine albumin-to-creatinine ratio, triglycerides, and gamma-glutamyl transferase. Liver stiffness and steatosis were assessed through transient elastography. MASLD was defined as a controlled attenuation parameter (CAP) of ≥274 decibels/meter (dB/m), while significant liver fibrosis was defined as a liver stiffness measurement (LSM) of ≥8 kPa. Multivariable logistic regression models, adjusted for potential confounders, were used to evaluate the association between IS and these liver outcomes. Results: A total of 1084 patients with T2D were analyzed. The prevalence of MASLD and significant liver fibrosis was 74.1% (95% CI 68.7–78.9) and 25.4% (95% CI 21.2–30.2), respectively. After adjusting for age, sex, waist circumference, and race/ethnicity, lower IS scores (indicating higher insulin resistance) were independently associated with increased odds of both MASLD (quartile 1 vs. quartile 4: OR 2.66, 95% CI 1.23–5.71) and significant liver fibrosis (quartile 1 vs. quartile 4: OR 3.30, 95% CI 1.45–7.51). These findings remained consistent across subgroups stratified by age, sex, and obesity status. Conclusions: This novel IS model, derived from commonly available clinical and biochemical markers, is independently associated with liver steatosis and fibrosis. Its application may help identify patients with more advanced MASLD, facilitating early intervention and risk stratification. Full article

This study investigates the impact of different noise levels on thermal comfort in outdoor environments. The research was conducted in two university squares in Xi’an, China, exhibiting distinct noise exposures, with twenty volunteers participating in the study. These individuals provided subjective evaluations of thermal comfort through questionnaires while situated in environments with disparate acoustic conditions in conjunction with the documentation of prevailing meteorological circumstances. The analysis yielded three salient findings. Initially, a marked elevation in perceived warmth was noted in environments experiencing higher noise levels, with 35.29% of subjects in the high-noise plaza (HP) reporting feeling warm (TSV = 2), which was 11.76 percentage points higher than in the low-noise plaza (LP). This included a 5.88 percentage point uptick in the frequency of “hot” (TSV = 3) thermal sensations reported in the HP. Furthermore, an intensification of thermal discomfort was observed in noisier settings, with the thermal comfort vote (TCV) in HP encompassing a spectrum from very uncomfortable to neutral and a predominant 90% of TCVs indicating discomfort, 35.29% of which were deemed very uncomfortable. Lastly, the findings suggest that high-decibel noise exposure notably amplifies the perception of heat within a specific high-temperature bandwidth. Beyond this delineated thermal threshold, the influence of noise on thermal sensation substantially diminishes. Full article

Quantum cryptography protocols offering unconditional protection open great rout to full information security in quantum era. Yet, implementing these protocols using the existing fiber networks remains challenging due to high signal losses reducing the efficiency of these protocols to zero. The recently proposed quantum-protected control-based key distribution (QCKD) addresses this issue by physically controlling interceptable losses and ensuring that leaked quantum states remain non-orthogonal. Here, we present the first in-field development and demonstration of the QCKD over an urban fiber link characterized by substantial losses. Using information-theoretic considerations, we configure the system ensuring security and investigate the interplay between line losses and secret key rates. As an example, we present calculation for the communication distance 4 km, QCKD rate 490 bits per second, and find that the corresponding system’s total loss is about 1.628 decibels. Our results, backed by the statistical analysis of the secret key, confirm QCKD’s robustness under real-world conditions, and establish it as a practical solution for quantum-safe communications over existing fiber infrastructures. Full article

This manuscript aims to optimize the acoustic scattering characteristics of underwater corner reflector linear arrays through simulation analysis and experimental validation, thereby enhancing their application efficiency in underwater acoustic countermeasures, particularly in terms of increasing acoustic echo intensity and reducing reflection blind spots. The acoustic scattering characteristics of submerged corner reflectors were meticulously simulated using the finite element method–boundary element method coupling technique, and the simulation results were rigorously verified through tank experiments. The study focused on the impact of the number of corner reflectors and their deployment angles on acoustic echo characteristics. Simulation and experimental results revealed that increasing the number of corner reflectors significantly enhances the overall target strength, with a dual corner reflector array achieving an approximately 5 decibels higher target strength than a single corner reflector. Moreover, the interaction of scattered acoustic waves among corner reflectors in the linear array generates noticeable fluctuations in the target strength curve, with these fluctuations increasing in frequency as the number of corner reflectors rises. By judiciously adjusting the deployment angles of the corner reflectors to achieve complementarity between strong and weak reflection angles, the issue of reduced target strength near 5° and 85° can be effectively mitigated, thereby significantly reducing reflection blind spots. Full article

The increasing demand for high-frequency applications and the widespread use of electromagnetic (EM) waves in communication systems necessitate the development of effective electromagnetic interference (EMI) shielding materials. This study investigates the structural and shielding effectiveness properties of novel polyaniline (PANI)-based NiO/ZnNb₂O₆ composites for sub-8 GHz applications. NiO and ZnNb₂O₆ were synthesized via conventional solid-state reactions and combined with PANI to form composites with varying compositions. X-ray diffraction (XRD) confirmed the successful formation of single-phase NiO and ZnNb₂O₆, while scanning electron microscopy (SEM) revealed well-defined microstructures, contributing to enhanced shielding efficiency. Shielding effectiveness (SE) measurements were performed across the 0–8 GHz frequency range using a vector network analyzer. Among the compositions tested, the epoxy-based NiO-ZnNb₂O₆ (75–25% by weight) with a 1:1 PANI ratio exhibited the highest SE value of −41.16 dB (decibels) at 6.24 GHz, demonstrating superior attenuation of EM waves. The observed shielding efficiency is attributed to multiple reflection effects, dipole interactions, and the conductive network formed by PANI. These findings highlight the potential of NiO/PANI/ZnNb₂O₆ composites as cost-effective, high-performance EMI shielding materials for next-generation microwave communication and electronic applications. Further optimization and hybridization approaches are recommended to enhance performance for broader frequency bands. Full article

Reducing friction-induced squeal noise is a common issue in daily life and industrial production, particularly for elastomers. However, adjusting structure and wettability in wet environments to solve the friction-induced squeal noise remains a challenge. Here, inspired by rabbit corneas, a microchannel nanofiber array composite structure superhydrophilic elastomer material was prepared to achieve rapid liquid spreading and optimize liquid distribution. Researchers have found that when the depth of the groove microchannel is 400 μm and the length of the nanofiber is 5000 nm, water rapidly spreads on the surface in only 430 ms. This reduces self-excited vibration caused by friction, thereby reducing squealing noise by 20 decibels (dB). This article proposes a novel and direct biomimetic squealing noise reduction strategy, which has great potential in solving friction vibration noise problems in industry and daily life, such as automotive wiper blades, engines, oil lubricated bearings, etc. Full article

The number of pistons in axial piston pumps plays a significant role in determining the performance characteristics of the pump. While increasing the number of pistons can improve capacity, stability, and flow, it also requires careful consideration of design complexity and operational efficiency. The optimal number of pistons will depend on the specific requirements of the application and the trade-offs that can be effectively managed. With multiple pistons operating together, the resulting pressure profile is smoother, reducing fluctuations that can affect system performance. This is crucial in applications where stable pressure is necessary, as it can improve the reliability and efficiency of the hydraulic system. Each piston contributes to the total displacement, resulting in an increase in flow rate. However, this must be balanced against the potential for increased internal friction and the complexity that can arise from multiple moving parts. The effect of the number of pistons on vibration and operating balance is another important factor. A well-balanced multi-piston pump can minimize pulsations and vibrations, resulting in smoother operation. This is essential for applications where excessive vibrations can lead to wear or system instability. To perform fast Fourier transforms (FFTs) on the measured signals, each signal was sampled at 4096 points per revolution (cycle). With five measured signals (four pressures and one vibration), this resulted in a total of (4 + 1) × 4096 = 20,480 data points per revolution and 204,800 data points for 10 consecutive revolutions. Full article

The fluvial acoustic tomography (FAT) system relies on the arrival time of the system signal to calculate the parameters of the region. The traditional method uses the matching filter method to calculate the peak position of the received acoustic signal after cross-correlation calculation within a certain time as the signal arrival time point, but this method is difficult to be effectively applied to the complex underwater environment, especially in the case of extremely low SNR. To solve this problem, a two-channel deep learning model (DCA-Net) is proposed to detect the arrival time of acoustic chromatographic signals. Firstly, an interactive module is designed to transmit the auxiliary information from the cross-correlation subnetwork to the original signal subnet to improve the feature information extraction capability of the network. In addition, an attention module is designed to enable the network to selectively focus on the important features of the received acoustic signals. Under the background of white Gaussian noise and real river environment noise, we use the received signals of the acoustic tomography system collected in the field to synthesize low SNR data of −10, −15, and −20 different decibels as datasets. The experimental results show that the proposed network model is superior to the traditional matching filtering method and some other deep neural networks in three low SNR datasets. Full article

In this study, it is shown that an efficient organic optocoupler (OPC) can be fabricated using commercially available and solution-processable organic semiconductors. The transmitter is a single-active-layer organic light-emitting diode (OLED) made from a well-known polyparavinylene derivative, Super Yellow. The receiver is an organic light-emitting diode (OLSD) with a single active layer consisting of a mixture of the polymer donor PTB7-Th and the low-molecular-weight acceptor ITIC; the receiver operates without an applied reverse voltage. OLED and OLSD have the same geometry and simple structure without any interlayers: glass/ITO/PEDOT:PSS/(active layer)/Ca/Al; the OPC is formed by OLED and OLSD which adhere tightly to each other. Despite its simple structure, the OPC showed a current transfer ratio of 0.13%, good linearity, and good dynamic performance: a three-decibel cutoff frequency of 170 kHz and response times to a step change in current at the OPC input of 2 μs. Compared to most organic OPC devices with similar performance parameters, where the transmitter and receiver have complex structures with additional interlayers between the active layers and electrodes and the need to apply a reverse voltage to the receiver, the simple design of our OPC reduces the number of fabrication steps and greatly simplifies the device fabrication process. Full article

To meet the critical need for compact, multifunctional acoustic vector sensors on deep-sea unmanned platforms such as acoustic profiling buoys and underwater gliders, we have developed a novel composite resonant acoustic vector sensor capable of large-depth operations. The sensor innovatively integrates the sound pressure channel and the vector channel, and utilizes the conjugate cross-spectrum between them to effectively reduce the isotropic noise, enhance the detection of weak signals from ships, and make up for the shortcomings of a single sound pressure channel and a vector channel. Certified to function reliably at depths up to 1500 m, field sea trials confirm its efficacy in deep-sea deployments, capturing essential marine environmental noise data. Key analysis during sea trials focused on marine ambient noise levels captured at frequencies of 65 Hz, 125 Hz, 315 Hz, 400 Hz, and 500 Hz, correlating these with changes in depth. The test results revealed the following insights: (a) At the same depth, the marine environmental noise level increases as the frequency decreases; (b) At the same frequency, the marine environmental noise level decreases with increasing depth; (c) Under favorable deep-sea conditions, the marine environmental noise level reaches 55 decibels (dB) at 500 Hz; (d) Noise levels tend to increase at various frequencies when surface ships are in proximity. These findings underscore its significant potential for enhancing deep-sea acoustic surveillance and exploration. Full article

This study investigates the application of Phased Array Corrosion Mapping (PACM) as a non-destructive testing (NDT) method for detecting and monitoring corrosion growth on hot stainless steel (SS) surfaces, specifically focusing on SS 304 and SS 316. Conducted across a temperature range of 30 °C to 250 °C, the research evaluates the effectiveness of PACM in high-temperature environments typical of the petrochemical industry. Experiments were conducted using specimens with machined slots and flat-bottom holes (FBHs) to simulate corrosion defects. The results demonstrate that PACM effectively detects and maps corrosion indicators, with color-coded C-scan data facilitating easy interpretation. Temperature variations significantly influenced ultrasound signal characteristics, leading to observable changes in FBH indications, particularly at elevated temperatures. Increased ultrasound attenuation necessitated adjustments in decibel settings to maintain accuracy. SS 304 and SS 316 exhibited distinct responses to temperature changes, with SS 316 showing higher dB values and unique signal behaviors, including increased scattering and noise echoes at elevated temperatures. Detected depths for slots and FBHs correlated closely with designed depths, with deviations generally less than 0.5 mm; however, some instances showed deviations exceeding 2 mm, underscoring the need for careful interpretation. At temperatures above 230 °C, the disbanding of probe elements led to weak or absent signals, complicating data interpretation and requiring adjustments in testing protocols. This study highlights the feasibility and effectiveness of PACM for corrosion detection on hot SS surfaces, providing critical insights into material behavior under thermal conditions. Future research should include physical examination of samples using Scanning Electron Microscopy (SEM) to validate and enhance the reliability of the findings. The integration of non-contact NDT methods and optimization of calibration techniques are essential for improving PACM performance at elevated temperatures. Full article

In this paper, the development of a low-cost acoustic sensor is presented based on an import-substituting element base as a cheap alternative to professional sensors or analog sensors. An Arduino board, a microphone module, a microSD card module, and other modules were used. To improve the accuracy of the data taken from the microphone, it was calibrated using a reference noise meter, using a logarithmic smoothing method to calculate the sound level in decibels, and an equation was formulated for converting the obtained ADC values into decibels. The code of the program executed by the sensor was developed and sewn into the device. The data captured from the microphone are stored in a CSV file with the date and time of the captured data. Full article

A new dual-band low-noise amplifier (LNA) operating at L1/E1 1.575 GHz and L5/E5 1.192 GHz center frequencies for global navigation satellite system receivers is proposed. A doubled common-source amplifier architecture is used with a single input, shared gate inductor, and two outputs to split the RF signal into separate RX channels. The main advantage of the proposed circuit is compatibility with widespread multi-band antennas with single RF connectors dedicated to high-precision applications, as well as the possibility to use cheap SAW filters with small footprints to build low-cost, highly accurate GNSS receiver modules. The input and both outputs are well matched to 50 Ω impedance. The LNA is designed with a 110 nm CMOS process, consuming 6.13 mA current from a 1.5 V supply. The measured noise figures and voltage gains of the dual-band LNA are, respectively, NF1/NF5 = 3.23/3.5 dB and G1/G5 = 21.22/18.2 dB in the band of interest for each channel. The measured impedance matching at the input (S11) and output (S22) of the dual-band low-frequency amplifier is as follows: S11_L1 = −23.89, S11_L5 = −8.42, S22_L1 = −12.65, S22_L5 = −15.08. The one-decibel compression points are L1 band PdB1 = −37.71 dBm and L5 band PdB5 = −34.72 dBm, respectively. Full article

This paper focuses on the non-destructive evaluation of adhesive joints used in vehicles designed for transporting food products. The research and analysis were limited to the joints used in connecting elements of the cargo space. Two non-destructive methods were employed in the study: ultrasonic and thermographic techniques. Both methods confirmed the feasibility of evaluating adhesive joints in the construction of food transport vehicles, with the thermographic method proving to be much faster in identifying large areas of deadhesion in the plating. The ultrasonic method, on the other hand, allows for the inspection of sheathing and aluminum profiles. The predefined decibel drop in the height of the first two pulses on the ultrasonic defectoscope screen for areas with high-quality joints was less than 3.5 dB. In contrast, for areas with adhesion-related damage, the decibel drop in the first two pulses exceeded 4.5 dB. Full article