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Purposes This research is carried out in order to systematically study the flow characteristics, heat and mass transfer characteristics of air flow field of open-cell metal foam. Methods The dodecahedron as a single cell of metal foam model is constructed by geometric representation. The influences of parameters of the cross-section shape of foam ligament, pore density (PPI), and the symmetry of foam structure in the direction of flow field at altitude on flow field distribution, mass transfer, and flow resistance at different inlet velocities are simulated by finite element method. Findings The results show that with the decrease of the vertex curvature of the foam ligament cross-section, the blocking of ligaments is weakened, and the friction loss (hf) of flow field decreases. Increasing the pore density can improve the distribution uniformity of convective intensity in flow field. In the height direction, the convection intensity of the asymmetric boundary field is greater, and the distribution of the convection intensity around ligaments tends to be uniform, while that of the symmetric structure is opposite. The convection velocities at the upper and lower boundaries of the symmetric boundary are slightly larger than those at the asymmetric boundary structure, and the symmetric structure is more conducive to mass transport at boundaries. The characteristics of open-cell metal foam structure and gas inlet velocity have obvious influences on the flow field distribution and flow resistance. The dimensional analysis results of the flow problem show that the more the number of pores, the greater the ratio of friction loss of flow field to the initial kinetic energy of the gas, and the ratio is reduced as the inlet velocity increasing. When the inlet velocity is greater than 6 m/s, the ratio tends to be stable.

ObjectiveTo determine the effects of varying positive end-expiratory pressures (PEEPs) on right ventricular function, hemodynamics, oxygenation, and the incidence of acute cor pulmonale (ACP) in patients with moderate-to-severe acute respiratory distress syndrome (ARDS).MethodsThis prospective paired-design study involved patients with moderate-to-severe ARDS in the ICU. Participants received lung-protective ventilation and hemodynamic monitoring. During the study, mechanical ventilation was administered with PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O, while maintaining an end-inspiratory plateau pressure ≤ 30 cmH2O. Various assessments, including transthoracic echocardiography, cardiac output measurement, and blood gas analysis, were conducted at baseline and after 1 h of ventilation at each PEEP. Subsequently, variations in ventilation oxygenation, echocardiographic parameters, and hemodynamic indicators under different PEEPs were analyzed to explore the potential effects of PEEP on right ventricular function and hemodynamics, as well as the incidence of ACP.ResultsA total of 317 ARDS patients were screened. Among them, 104 met the diagnostic criteria for moderate-to-severe ARDS, and 52 completed the study. The baseline PEEP of these 52 participants, acquired before commencement, was 11.5 ± 1.7 cmH2O, and the incidence of ACP was 25.0% (13/52). Intensive care unit mortality, overall hospital mortality, and 28-day mortality rates were 19.2% (10/52), 21.2% (11/52), and 32.7% (17/52), respectively. During the study, ACP incidences at PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O were 17.3% (9/52), 21.2% (11/52), and 38.5% (20/52), respectively. Meanwhile, the PaO2/FiO2 ratio improved with increasing PEEP, reaching 162.0 (140.9, 174.0), 171.0 (144.0, 182.0), and 176.5 (151.0, 196) mmHg at PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O, respectively. In addition, higher PEEPs were associated with a slight increase in PaCO2, showing statistically significant differences compared to moderate and low PEEPs. Compared to a PEEP of 5 cmH2O or 10 cmH2O, right ventricular function exhibited substantial changes at 15 cmH2O PEEP, manifested as increased pulmonary artery systolic pressure, enlarged right ventricular end-diastolic area, and decreased tricuspid annular plane systolic excursion, all with significant differences. Conversely, variations in left ventricular end-diastolic area and ejection fraction were not statistically significant. In terms of hemodynamics, increasing PEEP resulted in a decline in cardiac index (CI), with statistically significant differences between different PEEPs. Specifically, compared to the value at a PEEP of 5 cmH2O, the CI at a PEEP of 15 cmH2O decreased by 14.3% (2.63 [2.20, 2.95] vs. 3.07 [2.69, 3.67], p

An innovative local artificial boundary condition is proposed to numerically solve the Cauchy problem of the Klein-Gordon equation in an unbounded domain. Initially, the equation is considered as the axial wave propagation in a bar supported on a spring foundation. The numerical model is then truncated by replacing the half-infinitely long bar with an equivalent mechanical structure. The effective frequency-dependent stiffness of the half-infinitely long bar is expressed as the sum of rational terms using Pade approximation. For each term, a corresponding substructure composed of dampers and masses is constructed. Finally, the equivalent mechanical structure is obtained by parallelly connecting these substructures. The proposed approach can be easily implemented within a standard finite element framework by incorporating additional mass points and damper elements. Numerical examples show that with just a few extra degrees of freedom, the proposed approach effectively suppresses artificial reflections at the truncation boundary and exhibits first-order convergence.

This study systematically investigates the mechanism of magnetic coupling energy collection and designs an efficient energy collector. The experimental results demonstrate that the strategic installation of permanent magnets can effectively optimize the stress state of piezoelectric plates, significantly enhancing power generation efficiency. Under identical conditions, the peak voltage of the newly developed magnetically coupled energy collector reaches 168.3 V, surpassing the 67.19 V peak voltage reported in the reference. Optimizing the operational speed from 550 to 180 rpm improves the energy collector's compatibility with low-frequency external excitation. The study also compares and analyzes the power generation performance of various piezoelectric plates, revealing that the maximum power outputs of series and parallel circuits are 22.4 and 3.98 mW, respectively. This research introduces novel concepts and methodologies for optimizing the design of energy collector structures. [ABSTRACT FROM AUTHOR]

By anchoring the lower rollers and dynamically adjusting the upper roller's downfeed of a pyramid roll bender, one can achieve the precise bending of a workpiece into a desired planar form characterized by variable curvature. To ensure the seamless processing of individual cross sections without impinging upon adjacent areas, critical roller spacings are identified through theoretical mechanics analyses. The reaction force exerted on the top roller is calculated by integrating the desired curvature into the elastoplastic constitutive equation and subsequently deriving a dynamic adjustment of the downfeed from quasi-static finite element simulations. This preliminary downfeed protocol undergoes refinement to mitigate discrepancies between the targeted and the actual curvatures. Numerical instances demonstrate that the application of roller configurations, as outlined herein, yields a product profile that closely mirrors the intended curve. This congruence can be further improved with an additional iteration; however, subsequent iterations are seen to yield negligible improvements, indicating a rapid convergence of this algorithm. [ABSTRACT FROM AUTHOR]

Split-type flying car will play an important role in the future transportation. This paper adopts a guidance method that couples visual information and depth information, and improves the docking accuracy through the mutual cooperation of the drone and the vehicle. Firstly, a multilevel docking marker is designed to achieve adaptive target matching within different distances during the docking process. The marker has strong robustness and can adapt to complex scenes such as occlusion, strong light, and large angle tilting, providing the redundant corner points required for machine vision detection pose information accurately. Secondly, a three-dimensional pose estimation algorithm is proposed, which can introduce depth information to correct the homography matrix. The algorithm combines the advantages of strong robustness to multilevel marker detection and high accuracy of depth information, and can output millimeter-level precision pose information in different environments, different inclination angles, and different occlusions. Finally, a flying car model experiment was carried out, and the results showed that the guidance technology can obtain millimeter-level precise pose information during the entire process of long distance-near distance-completion of docking, thus realizing precise docking. [ABSTRACT FROM AUTHOR]

An improved impact damage model is proposed, which can be used to analyze the progressive failure behavior of fiber-reinforced composites. The model is constructed based on the 3D Hashin failure criterion. However, the difference is that the strain component along the thickness direction in the matrix energy evolution model is introduced, and the effects of and on impact damage are added. Rigid-body and bird-body impact problems are studied, which validates the accuracy of the numerical model by comparison with experiments. A 3D numerical model of light aircraft fuel tank impact is constructed, and the SPH-FEM coupling method is used to predict the bird strike failure problem. The structural damage and impact behavior of a light aircraft fuel tank under impact loading are analyzed. The results show that, under different impact energies, the damage to the matrix is more serious and expands along the fiber direction, and the structure presents different damage forms. This paper provides an effective research model for the study of drop shock and the airworthiness of composite fuel tanks. [ABSTRACT FROM AUTHOR]

Fatigue analysis and life prediction are the key and challenging issues in the mechanics research of composite material. In this paper, based on the progressive damage analysis method and fatigue cumulative damage theory, a three-dimensional fatigue cumulative damage numerical model is constructed by introducing the orthotropic constitutive equation, 3D-Hashin fatigue criterion, and material performance degradation scheme. Two loading conditions of tension–tension fatigue and compression–compression fatigue of Carbon Fiber composite laminates were investigated. In the tension–tension fatigue experiments, when the cycle is 10 6 times, the experiment and the numerical simulation all not completely destroyed. However, progressive degradation of stiffness and strength was observed in certain elements, accompanied by some internal damage. On the other hand, the experimental and predicted values for compression–compression fatigue were within a triple error band. Then the cumulative damage evolution law of each laminate under fatigue load was analyzed. Compression–compression fatigue damage initiated from the center of the hole and expanded to both sides of the composite laminate, and its fatigue life increased with the increase of the compression–compression fatigue load. Considering the degradation of stiffness in composite materials under fatigue loading, which leads to frequency attenuation in the structure, this paper established a connection between the fatigue state and frequency to obtain the frequency attenuation curve under fatigue loading. The relationship between frequency and fatigue life was revealed, allowing for the prediction of remaining fatigue life in practical engineering based on the rate of inherent frequency reduction. [ABSTRACT FROM AUTHOR]

In this paper, the three-dimensional progressive damage finite element models of composite bolted connection and adhesive-bolt hybrid connection were constructed, and the accuracy of the model is verified by comparing with the experimental results. The energy-based B-K criterion was used to simulate the damage and evolution of the adhesive layer, and the effects of bolt hole diameter, pre-tightening force and layup sequence on the failure characteristics of composite mechanical connections were analyzed. The results show that, in the bolted connection model, the final failure mode is typically extrusion damage near the bolt hole, with matrix failure being the primary form of failure. Appropriately increasing the diameter of the bolt hole or applying an appropriate pre-tightening force can both enhance the connection strength. Maximal strength of the connection structure is achieved when the first layer in the connection area is oriented at 0°, whereas if the first layer is oriented at 90°, the connection's bearing capacity is minimally reduced. In the adhesive-bolt hybrid connection model, the fiber and matrix damage of the four plies closest to the adhesive layer mainly spread along the 45°direction, and the damage is mainly matrix tensile damage. [ABSTRACT FROM AUTHOR]

Reservoir is a vital tool for human utilization of water resources, and the deterioration of its water quality can seriously threaten the water cycle and sustainable urban development. However, there are relatively few studies in academia that analyse and evaluate the water quality of multiple reservoirs at the same time. To address this knowledge deficit, we collected 108 water samples from three different reservoirs in Chuzhou City for 36 months (from 2019 to 2021), explored the drivers of changes in water quality parameters over time and the extent of eutrophication. Our results indicated that the water quality of the reservoirs was deteriorating during the study period, among which Huanglishu Reservoir and Shahe Reservoir reached mild eutrophic status, and both had higher eutrophication levels than Chengxi Reservoir. Secchi depth, total nitrogen and total phosphorus were the principal factors inducing eutrophication. The biassed utilization of reservoir functions was the major contributor to the discrepancy in the degree of eutrophication. Furthermore, Pearson correlation analysis revealed that there are significant correlations between many water quality parameters. Cluster analysis grouped the 12 months of each year into three clusters (stable water level period, rainy season high flow period and winter low flow period). Based on this, analysis of variance showed that most water quality parameters varied considerably between the clusters. Collectively, this study identified the actual water quality conditions of three reservoirs in Chuzhou City and provided guidance for local water quality management and environmental protection. [ABSTRACT FROM AUTHOR]

To solve the wave propagation problems of the Euler–Bernoulli beam in an unbounded domain effectively and efficiently, a new local artificial boundary condition technology is proposed. It replaces the residual right-hand side of the truncated discrete equation with an equivalent linear algebraic system. First, the equivalent Schrodinger equation is discussed. Its artificial boundary condition is obtained by first rationalizing the Dirichlet-to-Neumann condition in the frequency domain with a Pade approximation and then inverse transforming each Pade term back into the time domain by introducing auxiliary degrees of freedom. Frequency shifting is employed such that it performs better near a prescribed frequency. Then, the artificial boundary condition of the finite element Euler–Bernoulli beam is obtained by simple algebraic manipulations on that of the corresponding Schrodinger equation. This method only makes local changes to the original truncated discrete dynamic system and thus is very efficient and easy to use. The accuracy of the proposed method can be improved by using more Pade terms and a proper shift frequency. The numerical example shows, with only a few additional degrees of freedom, the proposed artificial boundary condition effectively eliminates the spurious reflection. The idea of the proposed method can also be used in other dispersive wave systems. [ABSTRACT FROM AUTHOR]

Nanofiber scaffolds have emerged as a revolutionary drug delivery platform for promoting wound healing, due to their unique properties, including high surface area, interconnected porosity, excellent breathability, and moisture absorption, as well as their spatial structure which mimics the extracellular matrix. However, the use of nanofibers to achieve controlled drug loading and release still presents many challenges, with ongoing research still exploring how to load drugs onto nanofiber scaffolds without loss of activity and how to control their release in a specific spatiotemporal manner. This comprehensive study systematically reviews the applications and recent advances related to drug-laden nanofiber scaffolds for skin-wound management. First, we introduce commonly used methods for nanofiber preparation, including electrostatic spinning, sol–gel, molecular self-assembly, thermally induced phase separation, and 3D-printing techniques. Next, we summarize the polymers used in the preparation of nanofibers and drug delivery methods utilizing nanofiber scaffolds. We then review the application of drug-loaded nanofiber scaffolds for wound healing, considering the different stages of wound healing in which the drug acts. Finally, we briefly describe stimulus-responsive drug delivery schemes for nanofiber scaffolds, as well as other exciting drug delivery systems. [ABSTRACT FROM AUTHOR]

This paper demonstrates a broadband dual‐polarized metasurface antenna with high isolation and low cross‐polarization using characteristic mode analysis. A wideband metasurface with stable radiation pattern is presented by splitting the edge patches into 2 × 2 sub‐array and introducing Minkowski fractal structure in the corner patches. To achieve the dual‐polarized operation, a pair of degenerate modes of the metasurface are selected, and thus high isolation and low cross‐polarization are obtained. The metasurface is excited by two slot antennas placed orthogonally. A prototype with an overall size of 1.46 λ0 × 1.46 λ0 × 0.07 λ0 (λ0 is the free‐space wavelength at center frequency) is fabricated. The proposed antenna could achieve dual‐polarization operation. The experiment results show that the −10 dB impedance bandwidths for each port are 28.9% (4.74–6.34 GHz) and 31.4% (4.62–6.34 GHz), respectively. The isolation between the two ports is higher than 31.8 dB, and cross‐polarization level is better than −28 dB. Moreover, broadside radiation performances for two ports are obtained. [ABSTRACT FROM AUTHOR]

This paper demonstrates a broadband metasurface antenna with stable gain. A 4 × 4 square patches metasurface loaded with nonuniform hexagonal slots is proposed. To achieve stable radiation performance in broadband range, two characteristic modes with the same current direction are selected as operating modes of the metasurface. A slot antenna is employed to excite the metasurface. By combining the resonant modes of metasurface and slot antenna, the broadband is obtained. The measured results show that, the −10 dB impedance bandwidth of the proposed antenna is 4.36–8.21 GHz (61.2%), the 2 dB gain bandwidth is 4.36–7.2 GHz (49.1%), and the peak gain value reaches 10.6 dBi. [ABSTRACT FROM AUTHOR]

A low‐profile dual‐band metasurface antenna is demonstrated for 4G LTE and 5G Sub‐6GHz applications. Based on the characteristic mode analysis, a wideband metasurface with stable radiation pattern is proposed by introducing Minkowski fractal structure in the edge patches and scaling the corner patches. The metasurface is operating in Sub‐6GHz band and excited by a Vivaldi bowtie slot antenna, which also serves as the radiator in LTE band. To validate the concept, a prototype with an overall size of 1.05λ0 × 1.05λ0 × 0.045λ0 (λ0 is the free‐space wavelength at 2.3 GHz) is fabricated. The experiment results show that the −10 dB impedance bandwidths in two bands are 1.7–2.78 (48.2%) and 3.2–5.01 GHz (44.1%), respectively. Moreover, broadside radiation performances in two bands are obtained. [ABSTRACT FROM AUTHOR]

Possessing long-range FM order and tunable interlayer magnetic coupling, extensive investigations of monolayered ferromagnetic chromium triiodide (CrI3) have been developed. In this work, by means of first-principles simulation, we systematically calculated the electronic and magnetic characteristic of two-dimensional (2D) CrI3 adsorbed by gas molecules, CO, H2, H2O and N2, which can provide theoretical guidance to modulate the desired properties of this layered material. The results show that the adsorption of those gas molecules can significantly enhance FM couplings of monolayer CrI3. In particular, the N2 adsorption can remarkably improve the Curie temperatures of the pristine CrI3 monolayer by about 2.6 times. We also hope that our findings can provide more interest around the recently studied 2D FM semiconductors. [ABSTRACT FROM AUTHOR]

At high current density, the mass transfer in proton exchange membrane fuel cells (PEMFC) is significantly influenced by the flow field structure. In this paper, a bilateral track flow field (BTFF) is proposed to improve the transverse and longitudinal mass transfer as well as the water removal capacity of PEMFC. The geometry of the BTFF is optimized by orthogonal tests to obtain the optimal combination of geometric parameters and levels. Then using numerical modeling, the impact of the optimized BTFF (BT6) on the efficiency of the PEMFC was examined. The results show that BT6 significantly improves the utilization of the under-rib region by shortening the reactive gas diffusion path length to obtain a more uniform oxygen distribution, and the average oxygen concentration in the midline of the under-rib of the BT6 is increased by 102.60%, furthermore, the current density is increased by 16.32% compared with that of the parallel flow field (case0). In addition, by reducing the cross-sectional area of the gas flow channel, the BT6 has a higher gas flow velocity, which accelerates the removal of cathode liquid water, and the average liquid water saturation in the midline of the under-rib of the BT6 is reduced by 15.26% compared with case0. Finally, by analyzing the net power density of PEMFC, it can be found that the net power density of BT6 is increased by 15.68% compared with case0, which has good practical application value. • A novel bilateral track flow field is proposed and optimized by orthogonal test. • Locally improved structure enhances transverse and longitudinal mass transfer. • The average oxygen concentration under-rib of the optimized flow field has increased by 102.60%. • The optimized flow field net power density has increased by 15.68%. [ABSTRACT FROM AUTHOR]

Citrus, one of the most widely cultivated fruit crops in the world, relies on arbuscular mycorrhizal fungi (AMF) to absorb nutrients and water from soil. However, the molecular mechanism of AM symbiosis (AMS) in citrus in general have largely been understudied. Here, using a TMT labeling proteomic approach, we identified 365 differentially expressed proteins (DEPs) in roots of Poncirus trifoliata (a common citrus rootstock) upon Rhizophagus irregularis colonization as compared with uninoculated roots, of which 287 were up-regulated and 78 were down-regulated. GO analysis revealed that the DEPs were mainly involved in biological processes such as negative regulation of endopeptidase inhibitor activity, negative regulation of endopeptidase, one-carbon metabolic process and carbohydrate metabolic process. KEGG enrichment analysis indicated that the DEPs were mainly involved in regulating metabolic pathways such as fatty acid biosynthesis, phenylpropanoid biosynthesis and carbon metabolism. Furthermore, 194 of the 365 DEPs were found to be associated with AMS-responsive genes by association analysis with our previous transcriptomes data, which highlighted the important roles of these proteins in AMS. One of the 194 DEPs, neutral ceramidase (PtNCER), was further chosen for function analysis via RNAi interfering its homologous gene MtNCER in a mycorrhizal model plant Medicago truncatula , which confirmed a positive role of NCER in AM establishment. Our results provided basic data and key candidate genes for genetic improvement of efficient nutrient uptake through AM establishment in citrus and other crops., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Yu, Ji, Zheng, Yu, Liu, Xiao and Pan.)

Lung adenocarcinoma, which is the second most prevalent cancer in the world, has a poor prognosis and a low 5-year survival rate. The MS4A protein family is crucial to disease development and progression, particularly for cancers, allergies, metabolic disorders, autoimmune diseases, infections, and neurodegenerative disorders. However, its involvement in lung adenocarcinoma remains unclear. In this study, we found that 11 MS4A family genes were upregulated or downregulated in lung adenocarcinoma. Furthermore, we described the genetic variation landscape of the MS4A family in lung adenocarcinoma. Notably, through functional enrichment analysis, we discovered that the MS4A family is involved in the immune response regulatory signaling pathway and the immune response regulatory cell surface receptor signaling pathway. According to the Kaplan-Meier curve, patients with lung adenocarcinoma having poor expression of MS4A2, MS4A7, MS4A14, and MS4A15 had a low overall survival rate. These four prognostic genes are substantially associated with immune-infiltrating cells, and a prognosis model incorporating them may more accurately predict the overall survival rate of patients with lung adenocarcinoma than current models. The findings of this study may offer creative suggestions and recommendations for the identification and management of lung adenocarcinoma., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zheng, Li, Yang and Guo.)

3D bioprinting is a revolutionary technology capable of replicating native tissue and organ microenvironments by precisely placing cells into 3D structures using bioinks. However, acquiring the ideal bioink to manufacture biomimetic constructs is challenging. A natural extracellular matrix (ECM) is an organ-specific material that provides physical, chemical, biological, and mechanical cues that are hard to mimic using a small number of components. Organ-derived decellularized ECM (dECM) bioink is revolutionary and has optimal biomimetic properties. However, dECM is always "non-printable" owing to its poor mechanical properties. Recent studies have focused on strategies to improve the 3D printability of dECM bioink. In this review, we highlight the decellularization methods and procedures used to produce these bioinks, effective methods to improve their printability, and recent advances in tissue regeneration using dECM-based bioinks. Finally, we discuss the challenges associated with manufacturing dECM bioinks and their potential large-scale applications., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: The most commonly acknowledged non-scarring alopecia are androgenetic alopecia (AGA) and alopecia areata (AA). Previous studies have revealed various risk factors associated with alopecia. However, the relationship between leukocyte telomere length (LTL) and non-scarring alopecia remains unclear., Methods: A two-sample Mendelian randomization (MR) analysis was performed to evaluate the causality between genetically predicted LTL and the risk of non-scarring alopecia. MR analyses were performed using the inverse variance-weighted (IVW) method and complemented with other MR methods., Results: The summary statistics of the genome-wide association studies (GWAS) for AGA and AA were obtained from the FinnGen biobank, which included 119,185 and 211,428 individuals, respectively. A total of 126 single nucleotide polymorphisms (SNPs) with genome-wide significance were selected as the instrumental variables for LTL. The MR analyses suggested a causal relationship between LTL and AGA, and the risk of AGA increased by 3.19 times as the genetically predicted LTL was shortened by one standard deviation in log transformed form under the IVW method (OR = 4.19, 95% CI = 1.20-14.61, p  = 0.024). The other MR methods also demonstrated a similar trend of the effect of LTL on AGA. There was no causal relationship between LTL and AA ( p  > 0.05). Sensitivity analyses further demonstrated that the current results were less likely to be affected by confounders and bias., Conclusion: Our results suggested a potential causal relationship between LTL and AGA, and shortened LTL was associated with an increased risk of AGA., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Yang, Liao, Zheng, Li, Wei, Liu and Yang.)