Search

Non-Hermitian systems with parity–time (PT)-symmetry have been extensively studied and rapidly developed in resonance wireless power transfer (WPT). The WPT system that satisfies PT-symmetry always has real eigenvalues, which promote efficient energy transfer. However, meeting the condition of PT-symmetry is one of the most puzzling issues. Stable power transfer under different transmission conditions is also a great challenge. Bound state in the continuum (BIC) supporting extreme quality-factor mode provides an opportunity for efficient WPT. Here, we propose theoretically and demonstrate experimentally that BIC widely exists in resonance-coupled systems without PT-symmetry, and it can even realize more stable and efficient power transfer than PT-symmetric systems. Importantly, BIC for efficient WPT is universal and suitable in standard second-order and even high-order WPT systems. Our results not only extend non-Hermitian physics beyond PT-symmetry, but also bridge the gap between BIC and practical application engineering, such as highperformance WPT, wireless sensing and communications. [ABSTRACT FROM AUTHOR]

Background: Gene expression profiles in breast tissue biopsies contain information related to chemotherapy efficacy. The promoter profiles in cell-free DNA (cfDNA) carrying gene expression information of the original tissues may be used to predict the response to neoadjuvant chemotherapy in breast cancer as a non-invasive biomarker. In this study, the feasibility of the promoter profiles in plasma cfDNA was evaluated as a novel clinical model for noninvasively predicting the efficacy of neoadjuvant chemotherapy in breast cancer. Method: First of all, global chromatin (5 Mb windows), sub-compartments and promoter profiles in plasma cfDNA samples from 94 patients with breast cancer before neoadjuvant chemotherapy (pCR = 31 vs. non-pCR = 63) were analyzed, and then classifiers were developed for predicting the efficacy of neoadjuvant chemotherapy in breast cancer. Further, the promoter profile changes in sequential cfDNA samples from 30 patients (pCR = 8 vs. non-pCR = 22) during neoadjuvant chemotherapy were analyzed to explore the potential benefits of cfDNA promoter profile changes as a novel potential biomarker for predicting the treatment efficacy. Results: The results showed significantly distinct promoter profile in plasma cfDNA of pCR patients compared with non-pCR patients before neoadjuvant chemotherapy. The classifier based on promoter profiles in a Random Forest model produced the largest area under the curve of 0.980 (95% CI: 0.978–0.983). After neoadjuvant chemotherapy, 332 genes with significantly differential promoter profile changes in sequential cfDNA samples of pCR patients was observed, compared with non-pCR patients, and their functions were closely related to treatment response. Conclusion: These results suggest that promoter profiles in plasma cfDNA may be a powerful, non-invasive tool for predicting the efficacy of neoadjuvant chemotherapy breast cancer patients before treatment, and the on-treatment cfDNA promoter profiles have potential benefits for predicting the treatment efficacy. [ABSTRACT FROM AUTHOR]

In this paper, several Kaczmarz-type numerical methods for solving the matrix equations AX = B and XA = C are proposed, where the coefficient matrix A may be full rank or deficient rank. These methods are iterative methods without matrix multiplication. Theoretically, the convergence of these methods is proved. The numerical results show that these methods are more efficient than iterative methods involving matrix multiplication for high-dimensional matrices. [ABSTRACT FROM AUTHOR]

Background: Evidence has revealed a connection between cuproptosis and the inhibition of tumor angiogenesis. While the efficacy of a model based on cuproptosis-related genes (CRGs) in predicting the prognosis of peripheral organ tumors has been demonstrated, the impact of CRGs on the prognosis and the immunological landscape of gliomas remains unexplored. Methods: We screened CRGs to construct a novel scoring tool and developed a prognostic model for gliomas within the various cohorts. Afterward, a comprehensive exploration of the relationship between the CRG risk signature and the immunological landscape of gliomas was undertaken from multiple perspectives. Results: Five genes (NLRP3, ATP7B, SLC31A1, FDX1, and GCSH) were identified to build a CRG scoring system. The nomogram, based on CRG risk and other signatures, demonstrated a superior predictive performance (AUC of 0.89, 0.92, and 0.93 at 1, 2, and 3 years, respectively) in the training cohort. Furthermore, the CRG score was closely associated with various aspects of the immune landscape in gliomas, including immune cell infiltration, tumor mutations, tumor immune dysfunction and exclusion, immune checkpoints, cytotoxic T lymphocyte and immune exhaustion-related markers, as well as cancer signaling pathway biomarkers and cytokines. Conclusion: The CRG risk signature may serve as a robust biomarker for predicting the prognosis and the potential viability of immunotherapy responses. Moreover, the key candidate CRGs might be promising targets to explore the underlying biological background and novel therapeutic interventions in gliomas. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) has great potential for applications in water-lubricated bearings; however, in heavy load conditions at low speeds, PTFE suffers from severe friction and abrasion because of its poor wear resistance. In this study, silicon carbide (SiC) content and particle size are investigated in relation to PTFE water-lubricated composites' tribological properties. The results show that the wear resistance of PTFE composites can be significantly improved when the filling amount of SiC particles was between 3 and 5 wt.%, and the composites containing 5 wt.% SiC reduced wear loss by 99.44%. The composites' friction and wear properties decreased as SiC particle size increased, and wear mechanism for the composites shifted from adhesive to abrasive. Wear loss on PTFE composites filled with 40 nm SiC particles was reduced by 97.03%, showing the best wear resistance. This study provides an experimental basis for the development of high-performance PTFE water-lubricated bearings. [ABSTRACT FROM AUTHOR]

Purpose: From a clinical point of view, how to force a transition from insomnia brain state to healthy brain state by external driven stimulation is of great interest. This needs to define brain state of insomnia disorder as metastable substates. The current study was to identify recurrent substates of insomnia disorder in terms of probability of occurrence, lifetime, and alternation profiles by using leading eigenvector dynamics analysis (LEiDA) method. Methods: We enrolled 32 patients with insomnia disorder and 30 healthy subjects. We firstly obtained the BOLD phase coherence matrix from Hilbert transform of BOLD signals and then extracted all the leading eigenvectors from the BOLD phase coherence matrix for all subjects across all time points. Lastly, we clustered the leading eigenvectors using a k-means clustering algorithm to find the probabilistic metastable substates (PMS) and calculate the probability of occurrence and associated lifetime for substates. Results: The resulting 3 clusters were optimal for brain state of insomnia disorder and healthy brain state, respectively. The occurred probabilities of the PMS were significantly different between the patients with insomnia disorder and healthy subjects, with 0.51 versus 0.44 for PMS-1 (p < 0.001), 0.25 versus 0.27 for PMS-2 (p = 0.051), and 0.24 versus 0.29 for PMS-3 (p < 0.001), as well as the lifetime (in TR) of 36.65 versus 33.15 for PMS-1 (p = 0.068), 14.36 versus 15.43 for PMS-2 (p = 0.117), and 14.80 versus 16.34 for PMS-3 (p = 0.042). The values of the diagonal of the transition matrix were much higher than the probabilities of switching states, indicating the metastable nature of substates. Conclusion: The resulted probabilistic metastable substates hint the characteristic brain dynamics of insomnia disorder. The results may lay a foundation to help determine how to force a transition from insomnia brain state to healthy brain state by external driven stimulation. [ABSTRACT FROM AUTHOR]

Motivated by unique topological semimetals in condensed matter physics, we propose an effective Hamiltonian with four degrees of freedom to describe evolutions of photonic double Weyl nodal line semimetals in one-dimensional hyper-crystals, which supports the energy bands translating or rotating independently in the form of Weyl quasiparticles. Especially, owing to the unit cells without inversion symmetry, a pair of reflection-phase singularities carrying opposite topological charges emerge near each nodal line, and result in a unique bilateral drumhead surface state. After reducing radiation leakages and absorption losses, these two singularities gather together gradually, and form a quasi-bound state in the continuum (quasi-BIC) ring at the nodal line ultimately. Our work not only reports the first realization of controllable photonics Weyl nodal line semimetals, establishes a bridge between two independent topological concepts−BICs and Weyl semimetals, but also heralds new possibilities for unconventional device applications, such as dual-mode schemes for highly sensitive sensing and switching. One-dimensional photonic crystals provide a platform to modulate Weyl quasiparticles with properties of bound states in the continuum both dynamically (transition and rotation) and topologically (singularities in bilateral drumhead surface states). [ABSTRACT FROM AUTHOR]

Vacancy defects are commonly present in crystals of energetic materials, and significantly influence the structural stability and decomposition mechanisms. However, there is a lack of profound understanding regarding the introduction of vacancy defects in energetic ionic salt, dihydroxylammonium 5,5′-bitetrazole-1,1′-dioxide (TKX-50). Due to the 1 : 2 ratio of anions to cations, TKX-50 possesses a more complex distribution of vacancy defects compared to traditional energetic materials. Based on the density functional theory method, the relatively favorable thermodynamic formation of vacancy defect distributions was revealed. The noncovalent interactions within the system, as well as the planarity of the anions, were investigated to understand the structural stability of TKX-50. Through ab initio molecular dynamics simulations, we discovered that vacancy defects can expedite the proton transfer during the initial decomposition stage of TKX-50 and affect the pathways of proton transfer. In the subsequent decomposition process, introduction of vacancy defects in the TKX-50 crystal leads to an earlier onset of ring-opening reactions and accelerates the appearance of decomposition products. The findings have the potential to provide insights into modeling vacancy defects in energetic ionic salts and reveal the impact of such defects on the structural stability and decomposition mechanisms of these materials. [ABSTRACT FROM AUTHOR]

Epsilon‐and‐mu‐near‐zero (EMNZ) metamaterials have garnered significant attention in near‐zero‐parameter metamaterial research for their exceptional ability to attain concurrent near‐zero permittivity and permeability. Nowadays achieving EMNZ properties through the use of metacomposites remains a novel endeavor. Presented here is an innovative approach of near‐zero‐parameter metacomposites, illustrating excellent and tunable EMNZ properties in the radio frequency regime. The self‐organization approach is applied to construct the conductive 3D network and the circuits, serving as the underlying framework for achieving EMNZ properties. Near‐zero permeability is effectively maintained while permittivity reaches epsilon‐near‐zero frequency regime. Efficient manipulation of electromagnetic parameters is initially realized via adjusting component content in metacomposites. Significantly, an excellent EMNZ property is observed as carbon content reaches 15 wt.% at 915 MHz. Through both numerical simulations and experimental testing, the PGC metacomposites have exhibited tunneling effects and directional emission characteristics, confirming their EMNZ properties. Besides, the Lego‐like adjustment facilitates the achievement of EMNZ property and advances the EMNZ frequency point to 700 MHz, expanding the EMNZ range. Furthermore, thanks to the remarkable excitation effect of photo‐induced adjustment, the metacomposite with low‐carbon content also achieves extraordinary EMNZ properties. This research offers promising self‐organized EMNZ metacomposites and lays the foundation for future endeavors in precisely adjusting near‐zero parameters. [ABSTRACT FROM AUTHOR]

For a graph G and positive integers t , k , a (t , k) -tree-vertex coloring of G refers to a t -vertex coloring of G satisfying every component of each induced subgraph generated by every set of vertices with the same color forms a tree with maximum degree not larger than k , and it is called equitable if the difference between the cardinalities of every pair of sets of vertices with the same color is at most 1. The strong equitable vertex k -arboricity of G , denoted by v a k ≡ (G) , is defined as the least positive integer t satisfying G , which admits an equitable (t ′ , k) -tree-vertex coloring for each integer t ′ with t ′ ≥ t. The strong equitable vertex k -arboricity of a graph is very useful in graph theory applications such as load balance in parallel memory systems, constructing timetables and scheduling. In this paper, we present the tight upper and lower bounds on v a k ≡ (G) for an arbitrary graph G with n vertices and a given integer k with 1 ≤ k ≤ n − 1 , and we characterize the extremal graphs G with v a k ≡ (G) = 1 , v a k ≡ (G) = ⌈ n / 2 ⌉ − 1 , v a k ≡ (G) = ⌈ n / 2 ⌉ , respectively. Based on the above extremal results, we further obtain the Nordhaus–Gaddum-type results for v a k ≡ (G) of graphs G with n vertices for a given integer k with 1 ≤ k ≤ n − 1. [ABSTRACT FROM AUTHOR]

In order to suppress the transverse vibration of a plate, a quasi-zero-stiffness (QZS) resonator with tunable ultralow frequency bandgaps was introduced and analyzed. The resonator was designed by introducing the quasi-zero-stiffness systems into mass-in-mass resonators. The plane wave expansion method was employed to derive the bandgap characteristics of the locally resonant (LR) plate with QZS resonators, and corresponding simulations were carried out by finite element method (FEM). The results show that an LR plate with a QZS resonator can provide two bandgaps, and the ranges of the bandgaps agree well with the vibration attenuation bands calculated by FEM. Owing to the introduction of the QZS system, the bandgaps can be easily transferred to a lower frequency or even an ultralow frequency. The damping of the QZS resonators can effectively broaden the vibration attenuation bands. In addition, the differentiated design of the bandgap frequencies can be realized to obtain broadband low-frequency transverse wave suppression performance. Finally, a mechanical structure design scheme was proposed in order to achieve flexible adjustment of the bandgap frequency, which significantly increases the engineering applicability of QZS resonators. [ABSTRACT FROM AUTHOR]

A compatible spanning circuit in an edge-colored graph G (not necessarily properly) is defined as a closed trail containing all vertices of G in which any two consecutively traversed edges have distinct colors. The existence of extremal compatible spanning circuits (i.e., compatible Hamilton cycles and compatible Euler tours) has been studied extensively. Recently, sufficient conditions for the existence of compatible spanning circuits visiting each vertex at least a specified number of times in specific edge-colored graphs satisfying certain degree conditions have been established. In this paper, we continue the research on sufficient conditions for the existence of such compatible s-panning circuits. We consider edge-colored graphs containing no certain forbidden induced subgraphs. As applications, we also consider the existence of such compatible spanning circuits in edge-colored graphs G with κ(G) ≥ α(G), κ(G) ≥ α(G) − 1 and κ (G) ≥ α(G), respectively. In this context, κ(G), α(G) and κ (G) denote the connectivity, the independence number and the edge connectivity of a graph G, respectively. [ABSTRACT FROM AUTHOR]

In this paper, two randomized block Kaczmarz methods to compute inner inverses of any rectangular matrix A are presented. These are iterative methods without matrix multiplications and their convergence is proved. The numerical results show that the proposed methods are more efficient than iterative methods involving matrix multiplications for the high-dimensional matrix. [ABSTRACT FROM AUTHOR]

Ceramic materials are widely used in engineering field because of their good physical and chemical properties. The poor mechanical properties of traditional ceramics seriously limit the development of ceramic materials and have attracted extensive attention since its birth. The development of high toughness, light weight, and functional ceramic materials has long been the pursuit of materials scientists. Since ancient times, nature has been the source of all kinds of human technological ideas, engineering principles, and major inventions. The functional structure of biology provides a good research object for the bionic design and preparation of ceramic materials. Therefore, it is necessary to summarize the functional structures and mechanisms in nature and biomimetic preparation technology. The purpose of this review is to provide guidance for the functionalized biomimetic design and efficient preparation of ceramic materials. Some typical functional examples in nature are introduced in detail, and several representative biomimetic preparation methods are listed. Finally, the performance and application status of biomimetic ceramics are summarized, and the future development direction of biomimetic ceramic materials is prospected. [ABSTRACT FROM AUTHOR]

With the development of green tribology in the shipping industry, the application of water lubrication gradually replaces oil lubrication in stern bearings and thrust bearings. In terms of large-scale and high-speed ships, water-lubricated bearings with high performance are more strictly required. However, due to the lubricating medium, water-lubricated bearings have many problems such as friction, wear, vibration, noise, etc. This review focuses on the performance of marine water-lubricated bearings and their failure prevention mechanism. Furthermore, the research of marine water-lubricated bearings is reviewed by discussing its lubrication principle, test technology, friction and wear mechanism, and friction noise generation mechanism. The performance enhancement methods have been overviewed from structure optimization and material modification. Finally, the potential problems and the perspective of water-lubricated bearings are given in detail. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) technology based on magnetic resonance (a basic physical phenomenon) can directly transfer energy from the source to the load without wires and other physical contacts, and has been successfully applied to implantable medical devices, electric vehicles, robotic arms and other fields. However, due to the frequency splitting of near-field coupling, the resonant WPT system has some unique limitations, such as poor transmission stability and low efficiency. Here, we propose anti-resonance with level pinning for high-performance WPT. By introducing the anti-resonance mode into the basic WPT platform, we uncover the competition between dissipative coupling and coherent coupling to achieve novel level pinning, and construct an effective anti-parity-time (anti- PT)-symmetric non-Hermitian system that is superior to previous PT -symmetric WPT schemes. On the one hand, the eigenvalue of the anti- PT -symmetric system at resonance frequency is always pure real in both strong and weak coupling regions, and can be used to overcome the transmission efficiency decrease caused by weak coupling, as brought about by, for example, a large size ratio of the transmitter to receiver, or a long transmission distance. On the other hand, due to the level pinning effect of the two kinds of coupling mechanisms, the working frequency of the system is guaranteed to be locked, so frequency tracking is not required when the position and size of the receiver change. Even if the system deviates from the matching condition, an efficient WPT can be realized, thereby demonstrating the robustness of the level pinning. The experimental results show that when the size ratio of the transmitter coil to the receiver coil is 4.29 (which is in the weak coupling region), the transfer efficiency of the anti- PT -symmetric system is nearly 4.3 (3.2) times higher than that of the PT -symmetric system when the matching conditions are satisfied (deviated). With the miniaturization and integration of devices in mind, a synthetic anti- PT -symmetric system is used to realize a robust WPT. Anti- PT -symmetric WPT technology based on the synthetic dimension not only provides a good research platform for the study of abundant non-Hermitian physics, but also provides a means of going beyond traditional near-field applications with resonance mechanisms, such as resonance imaging, wireless sensing and photonic routing. [ABSTRACT FROM AUTHOR]

With the growing public attention on sustainable development and green ecosystems, the efficient management of fuzzy sewage treatment processes (FSTPs) has been a major concern in academia. Characterized by strong abstraction and analysis abilities, data mining technologies provide a novel perspective to solve this problem. In recent years, data-driven management for FSTP has been widely investigated, resulting in a number of typical approaches. However, almost all existing technical approaches consider FSTP a unidirectional, sequential process, ignoring the bidirectional temporality caused by backflow operations. Therefore, we propose a data-driven management mechanism for FSTP based on hybrid neural computing (IM-HNC for short). This mechanism attempts to capture the bidirectional time-series features of FSTP with the aid of a bidirectional long short-term memory model, and further introduces a convolutional neural network to construct feature spaces with a stronger expression capability. Empirically, we implement a series of experiments on three datasets under different parameter settings to test the efficiency and robustness of the proposed IM-HNC. The experimental results manifest that the IM-HNC has an average performance improvement of approximately 5% compared to the baselines. [ABSTRACT FROM AUTHOR]

Lignum vitae, one of the earliest manufacturing materials used in water-lubricated bearings, is renowned for its exceptional tribological performance. The key factor behind this remarkable wear resistance lies in Lignum vitae's internal vessel structure. In this study, a lubrication model based on the natural hollow-tube vessel was conducted to simulate the hydrodynamic lubrication of Lignum vitae in actual working condition and a novel biomimetic composite was manufactured. The influence of the hollow-tube structure on tribological performance was investigated both theoretically and experimentally. Through an extensive series of simulations, wear tests, and characterization under water-lubricated conditions, the results demonstrated that the presence of the hollow-tube structure positively impacts tribological performance. Moreover, it is found that the size and density of these tubes are directly correlated with this improvement; specifically reducing the coefficient of friction by 47 percent and reducing the wear volume by 69 percent. By combining simulation and experimental data, our discussion reveals that the hollow-tube structure significantly enhances lubricant storage capacity and reduces abrasion at frictional interfaces. This comprehensive analysis sheds light on Lignum vitae's internal structural parameters while establishing clear correlations between these parameters and its tribological performance. [ABSTRACT FROM AUTHOR]

Ultralow-frequency band gaps are realized to suppress the ultralow-frequency flexural wave propagation in the beams with periodically attached quasi-zero-stiffness (QZS) resonators, which are designed by inserting quasi-zero-stiffness systems into the mass-in-mass structures. The band structure and the transfer matrix of the QZS locally resonant beam are derived by the transfer matrix method to quantify the wave attenuation performance of band gaps. Then, the effect of the stiffness ratio on the bandgap characteristic is studied. It is shown that, thanks to the introduction of the QZS system, the band gaps can be easily transferred to lower frequency or even ultralow frequency without weakening the static stiffness of the resonators. Finally, the flexural wave propagation in locally resonant beam consisting of multiple periodic arrays of QZS resonators is investigated. The result shows that differential design of the bandgap frequencies can be easily realized by adjusting the negative stiffness coefficient of the QZS resonators, so as to obtain broadband flexural wave suppression performance. [ABSTRACT FROM AUTHOR]

In order to investigate the friction and wear properties of polymer materials used for mechanical seals of ship stern shafts in actual working environments, five materials, namely, cast polyurethane elastomer (CPU), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), glass fiber modified polyhexamethylene butylamine (CF/PA46) composite, and glass fiber modified polytetrafluoroethylene (CF/PTFE) composite, were selected, and their friction and wear performance tests were conducted under the load of 0. 5 MPa and the linear velocity of 7 m/s. The results show that CPU, PET, PBT, CF/PA46 materials exhibit varying degrees of peeling and furrowing under high load and high rotational speed conditions, resulting in large friction coefficients and wear losses, while CF/PTFE composites only exhibit some relatively slight tears and wear marks, exhibiting optimal friction and wear performance. Compared to CPU, PET, PBT, and CF/PA46, the average friction coefficient of CF/PTFE is decreased by 66. 6%,80. 4%,86. 1%,and 87. 8%,respectively, and the wear amount per unit time is decreased by 91. 7%,92. 7%,88. 6%,and 97. 0%, respectively. The friction and wear performance is optimal. [ABSTRACT FROM AUTHOR]

In order to improve the bearing capacity of water-lubricated bearings, the tribological properties of thermoplastic polyurethane (TPU) bearing materials were improved by the hydration of hydrogels under water lubrication conditions. Hydrogel particles were prepared by using polyvinyl alcohol, sodium alginate, chitosan and other materials, and hydro-gel/TPU composites were prepared by melt blending. The friction and wear properties of the composites were tested under loads of 0. 3 MPa and 0. 5 MPa. The wear surface morphology was observed by laser interference surface profiler and scanning electron microscope, and the wear mechanism was analyzed. The results show that the hydrogel particles can improve the lubrication condition of the friction pair through hydration lubrication, thereby reducing the friction coefficient and wear amount, and improving the friction performance of the composite. When the mass fraction of hydrogel is 4%,the composite has the best friction and wear properties, and compared with the TPU sample, the average friction coefficient reduction rate under the working conditions of 0. 3 MPa and 0. 5 MPa is 52. 31% and 43. 94%, respectively. This research provides a method for developing high performance materials for water lubricated bearings. [ABSTRACT FROM AUTHOR]

As a kind of phase singularity in physical systems, exceptional points (EPs) give rise to a plethora of counterintuitive phenomena, such as the asymmetric state transfer and unidirectional reflection. Especially, the eigenvectors of EP are self-orthogonal, and an inherent chirality can be determined because of the "missing dimension." Beyond traditional wisdom, in this work, we proposed theoretically an effective anti-parity-time symmetry in a non-Hermitian system under the external excitation, and the chirality reversal from resonance EP to absorption EP is demonstrated experimentally. The essence of this phenomenon is that the external input is involved in the establishment of the eigenstates of the system. Moreover, the critical condition of chirality reversal between two types of EPs in the non-Hermitian system is analytically given. This external excitation-controlled EP not only paves an effective way to study the fundamental non-Hermitian physics in an open system but also holds great potential in the applied photonic devices such as the chiral antenna, polarization converter, and wireless communication. [ABSTRACT FROM AUTHOR]

In order to improve the vibration reduction performance of damping treatments, a new damping structure consisting of a uniform base layer and two periodically alternating free layers was examined in this study. Closed-form solutions for both the band structure and the forced response of the periodic bi-layer beam were theoretically derived and verified via numerical solutions using the finite-element method. The results showed that the structure with periodic free-layer damping (PFLD) treatment reduced broadband vibrations, and the levels of reduction were dominated by Bragg scattering in the band gaps and damping in the passbands. The vibration experiment verified the derived theory's accuracy and showed that the PFLD treatment could increase vibration reduction levels in low-frequency band gaps compared with traditional free-layer damping treatments. The effects of the parameters—cell lengths, sub-cell-length ratios, and thickness ratios—were also discussed, providing further understanding of the vibration reduction performance of the bi-layer beam with the PFLD treatment, and this can be used to help designers optimize the periodic bi-layer beam to achieve better performance. [ABSTRACT FROM AUTHOR]

Polyurethane has been extensively studied as a multifunctional material for water‐lubricated bearing materials. As one of the polyurethane elastomeric synthetic material, the content of 4,4′‐methylene bis(2‐chloroaniline) (MOCA) directly affects the intermolecular structure and thus the properties of the material. Five samples with different MOCA contents were prepared by casting molding and tested. The results showed that the optimal comprehensive performance was obtained when the ratio of the amino group to the hydrocyanic acid group was 0.95, with tensile, compressive, and bending strengths of 50.1, 91.8, and 12.6 MPa, respectively. Compared with other samples, the surface of the sample was smooth, which was conducive to the formation of the water film. The bearing capacity and lubrication condition are improved, and the best tribological performance was shown. This research for the application of polyurethane elastomer on the water‐lubricated bearing provides a theoretical basis. [ABSTRACT FROM AUTHOR]

The interaction between cavity field and atoms plays an important role in exploring the abundant non-Hermitian physics and constructing powerful wave function devices. In this work, we propose theoretically and realize experimentally unidirectional perfect absorption in a non-Hermitian acoustic system with the help of the topological bound state in the continuum (BIC), which is established by the hybrid interaction between one trivial BIC and another conventional resonant state. In the 2D parameter space spanned by frequency and distance between the two resonators, the topological scattering singularities appear in pairs and are associated with topological distinguished charges. Meanwhile, we reveal the origin of topological charges and their continuous evolution with the loss factor. At a specific loss factor, two topological charges just annihilate together, and acoustic perfect absorption induced by topological BIC is realized at the left incidence, while there is no phase singularity and near-total reflection is observed at the right incidence, hence the system presents extreme asymmetry. Our work bridges the gap between scattering characteristics of non-Hermitian acoustic systems and topological scattering singularities, which may contribute to the research of novel non-Hermitian physics and the practical applications of advanced absorbers and sensors. [ABSTRACT FROM AUTHOR]

With the development of emerging information technology, the traditional management methods of marine fishes are slowly replaced by new methods due to high cost, time-consumption and inaccurate management. The update of marine fishes management technology is also a great help for the creation of smart cities. However, some new methods have been studied that are too specific, which are not applicable for the other marine fishes, and the accuracy of identification is generally low. Therefore, this paper proposes an ecological Internet of Things (IoT) framework, in which a lightweight Deep Neural Networks model is implemented as a image recognition model for marine fishes, which is recorded as Fish-CNN. In this study, multi-training and evaluation of Fish-CNN is accomplished, and the accuracy of the final classification can be fixed to 89.89%–99.83%. Moreover, the final evaluation compared with Rem-CNN, Linear Regression and Multilayer Perceptron also verify the stability and advantage of our method. [ABSTRACT FROM AUTHOR]

Background: Coronary artery ectasia is defined as a local or diffuse dilatation of the coronary artery more than 1.5 times the diameter of the adjacent normal segment. The etiology of coronary artery ectasia is diverse, and rarely complicated with immunoglobulin G4-related disease (IgG4-related disease). A limited number of cases have been reported, with insidious onset, slow progression but poor prognosis. Case presentation: we report a patient with coronary artery ectasia combined with IgG4-related disease. He has been diagnosed with IgG4-related disease 5 years after his first percutaneous coronary intervention (PCI). Despite routine treatment with steroids, he develops a large coronary aneurysm and eventually died. Conclusions: It is suggested that a thorough evaluation should be performed when coronary artery ectasia is diagnosed. The factors such as manifestations of coronary artery thickening, typical imaging features, other aortas involvement, increased serum IgG4 level, etc. should be considered for early diagnosis of key etiologies. [ABSTRACT FROM AUTHOR]

Objective: Insomnia disorder with objective short sleep duration (ISS) has been considered as a biologically severe subtype. The aim of this meta-analysis was to reveal the association of the ISS phenotype and cognitive performance. Methods: We searched PubMed, EMBASE, and the Cochrane Library for studies that observed an association of cognitive performance and insomnia with objective short sleep duration (ISS) phenotype. The "metafor" and "MAd" packages in R software (version 4.2.0) were used to calculate the unbiased standardized mean difference (Hedge's g), which was adjusted so that a negative value indicated worse cognitive performance. Results: The pooled analysis with 1339 participants revealed that the ISS phenotype was associated with overall cognitive impairments (Hedges' g = − 0.56 [− 0.89, − 0.23]), as well as specific cognitive domains including attention (Hedges' g = − 0.86 [− 1.25, − 0.47]), memory (Hedges' g = − 0.47 [− 0.82, − 0.12]), and executive function (Hedges' g = − 0.39 [− 0.76, − 0.02]). However, cognitive performance was not significantly different between insomnia disorder with objective normal sleep duration (INS) and good sleepers (p >.05). Conclusion: Insomnia disorder with the ISS phenotype, but not the INS phenotype, was associated with cognitive impairments, suggesting the possible utility of treating the ISS phenotype to improve cognitive performance. [ABSTRACT FROM AUTHOR]

Manipulating the properties of the isofrequency contours (IFCs) of materials provides a powerful means of controlling the interaction between light and matter. Hyperbolic metamaterials (HMMs), an important class of artificial anisotropic materials with hyperbolic IFCs, have been intensively investigated. Because of their open dispersion curves, HMMs support propagating high-k modes and possess an enhanced photonic density of states. As a result, HMMs can be utilized to realize hyperlenses breaking the diffraction limit, metacavity lasers with subwavelength scale, high-sensitivity sensors, long-range energy transfer, and so on. Aimed at those who are about to enter this burgeoning and rapidly developing research field, this tutorial article not only introduces the basic physical properties of HMMs but also discusses dispersion manipulation in HMMs and HMM-based structures such as hypercrystals. Both theoretical methods and experimental platforms are detailed. Finally, some potential applications associated with hyperbolic dispersion are introduced. [ABSTRACT FROM AUTHOR]

Recently, wireless power transfer (WPT) technology has attracted much attention and shown rapid development. However, a fundamental challenge emerges in practical applications: how to achieve robust power transfer against the variation of operating conditions, such as the fluctuation of transfer distance, as well as the relative orientation of resonant coils. In this article, we theoretically propose and experimentally demonstrate that the robustness of a parity-time (PT) asymmetric system with unbalanced gain-loss working in a weak coupling region can be improved significantly, compared with that of a PT-symmetric system with balanced gain-loss working in a strong coupling region under the premise that the system works at a fixed optimal frequency. A pure real mode known as bound state in the continuum (BIC) in the weak coupling region of the PT-asymmetric system is adopted to ensure the high efficiency and stability of the WPT and break the limitations of balanced gain-loss of the PT-symmetric system. The better robustness performance originates from the orthogonal state with a pure real eigenmode embedded in the weak coupling region. Further experiments also verify that the PT-asymmetric system can achieve higher efficiency than that of the PT-symmetric system. In addition, we discuss the performance of the WPT system based on the theories of coupled mode theory (CMT) and circuit theory (CT); the BIC in the framework of CMT and a perfect impedance matching condition in the framework of CT for efficient power transfer are consistent. We also conducted power experimental verification of 30 watts, and found the efficiency between the coils can reach over 90% in dynamic scenarios, which meets expectations. The presented framework extends the field of non-Hermitian physics, bridges the gap between the non-ideal PT-symmetric system and a practical engineering application, and introduces a novel WPT mechanism for flexible application scenarios. Our results could provide instructive significance for practical applications of the WPT system in the long term. [ABSTRACT FROM AUTHOR]

The performance of cylinder liner piston ring (CLPR) that worked under harsh conditions significantly affected the reliability of diesel engines. Nano‐copper lubricant additives have recently been introduced due to their good anti‐wear properties. This study aims to gain insights into the interactions between concentrations of nano‐copper lubricant additives and the tribological performance of CLPR. Tests are performed on a reciprocating sliding test rig under different operating conditions, and the tribological performances are characterized by the friction coefficient, wear mass losses, and morphologies of worn surface. The experimental results indicated that the optimal concentration of nano‐copper additives is 2 wt%. Additionally, deposition of the Cu nanoparticles on the worn surface during the friction process facilitates the formation of the mending layer. These findings would aid to provide a technical reference for the application of nano‐copper additives in diesel engines. [ABSTRACT FROM AUTHOR]

Light propagates in various ways depending on environment, including uniform medium, surface/interface and photonic crystals, which appears ubiquitously in daily life and has been exploited for advanced optics technology. We unveiled that a topological photonic crystal exhibits unique electromagnetic (EM) transport properties originating from the Dirac frequency dispersion and multicomponent spinor eigenmodes. Measuring precisely local Poynting vectors in microstrips of honeycomb structure where optics topology emerges upon a band gap opening in the Dirac dispersion and a p-d band inversion induced by a Kekulé-type distortion respecting C6v symmetry, we showed that a chiral wavelet induces a global EM transportation circulating in the direction counter to the source, which is intimately related to the topological band gap specified by a negative Dirac mass. This brand-new Huygens-Fresnel phenomenon can be considered as the counterpart of negative refraction of EM plane waves associated with upwardly convex dispersions of photonic crystals, and our present finding is expected to open a new window for photonic innovations. Huygens-Fresnel features are useful for harnessing light in unique ways. Here the authors demonstrate a chiral light source that induces globally a counter energy flow in a topological photonics structure with Dirac-type frequency dispersion. [ABSTRACT FROM AUTHOR]

Since wastewater treatment processes (WTP) are generally accompanied with intense coupling and fuzziness, conventional biochemical mechanisms-based methods cannot comprehensively express the WTP due to limited computational ability. In response to the challenge caused by fuzziness, this paper proposes a hybrid control and prediction system for modeling WTP with the fuse of Activated Sludge model, Convolutional neural network and Long short-term memory neural networks (AS-CL) with knowledge and data-driven characteristics. Moreover, the activated sludge model is employed to model the wastewater treatment process based on the perspective of knowledge. Besides, the hybrid neural network that combines convolutional neural network and long short-term memory model is adopted to model the WTP from the perspective of data. Then, a multi-layer perception model is set up to realize collaborative awareness of data and knowledge. Lastly, the proposed AS-CL has been evaluated by a real-world data-set collected from a real sewage treatment plant. The results show that compared with typical existing methods, the proposal improves modeling efficiency. With the collaborative modeling scheme, influence from fuzziness on WTP can be reduced to some extent. Compared with five benchmark methods of the two evaluation indexes, the results of AS-CL show that the average performance of this method exceeds 7% of the baseline. [ABSTRACT FROM AUTHOR]

A compatible Euler trail (tour) in an edge-colored graph is an Euler trail (tour) in which each two edges traversed consecutively along the Euler trail (tour) have distinct colors. In this paper, we show that the problem of counting compatible Euler trails in edge-colored graphs is # P-complete, and develop O(mN) time algorithms for enumerating compatible Euler trails (tours) in edge-colored graphs with m edges and N compatible Euler trails (tours). It is worth mentioning that our algorithms can run in O(N) time when there is no vertex v with degree 4 and maximum monochromatic degree 2. [ABSTRACT FROM AUTHOR]

As one of the important friction pairs of a diesel engine, the cylinder-liner piston ring (CL-PR) faces a harsh high-temperature working environment. To explore the mapping relationship between the friction performance of the CL-PR and the change in temperature, the reciprocating-friction and wear-testing machine was used to analyze the friction performance and lubrication performance of four kinds of lubricating oil at different temperatures (room temperature, 60 °C, 90 °C, and 120 °C) from the friction coefficient, contact resistance and surface topography. The results show that the tribological properties of the four lubricating oils show different trends with the increase in temperature. The friction coefficient of the base oil first decreases and then increases with the increase in temperature; this shows that the friction property of the base oil is improved by a certain temperature rise, and the increase in temperature promotes the formation of an oxide film and reduces the friction coefficient. While the friction coefficient of other three lubricating oils with specific application scenarios increases first and then remains stable, the wear of the friction pair is the most severe at 120 °C. The wear forms are abrasive wear and adhesive wear. [ABSTRACT FROM AUTHOR]

The effects of surface-texture technology on the friction and lubrication mechanism of cylinder liner-piston rings (CLPR) were explored in this study. An inclined groove texture was machined on the CL of a S195 diesel engine and dimples designed on the gas ring. Friction and wear tests of nontextured (NT), CL textured (CLT), and PR textured (PRT) conditions were performed on a CLTR friction and wear tester under different temperatures. First, the characteristics of friction and lubrication at different temperatures were analyzed by examining friction and contact resistance. Then, the wear characteristics were analyzed by examining surface morphology parameters of the CL and the PR wear mass after testing. Finally, the friction and lubrication mechanisms of NT, CLT, and PRT were studied by analyses of real-time friction and contact resistance in one cycle. The results showed that, under the same temperature, CLT and PRT increased oil film thickness, improved the lubrication state, and reduced friction, with CLT better than PRT in these respects. With increased temperature, the wear degree of CL liners became larger. The existence of surface texture reduced CL wear, yielded CL surface morphology not excessively changed by temperature, and improved its supporting performance and oil storage capacity. The inlet suction effect, structural effect, micro-wedge action, balancing wedge action, squeezing effect, and cavitation effect should be taken into account together when exploring the mechanism of the influence of surface texture on friction pairs. This study provided a method for scholars to explore the friction and lubrication mechanism of different texture types and provided an experimental basis for improving the performance of CLPR friction pairs. [ABSTRACT FROM AUTHOR]

In industrial recirculating aquaculture systems (IRAS), the autonomous decision control of feeding strategies remains a practical concern. Conventionally, control schemes were established from data‐driven view, which fails to comprehensively perceive activity status of fishes. To deal with this issue, a deep vision sensing‐based fuzzy control scheme is proposed for smart feeding in IRAS. In the first stage, a deep learning‐based object detection model is introduced to capture two aspects features as the decision factors: residual bait and eating frequency. In the second stage, a fuzzy neural network model is formulated to calculate control decision strategies via fuzzy inference. And experiments on real‐world visual scenes are conducted to verify the proposal. [ABSTRACT FROM AUTHOR]

Since medical diagnosis runs through the whole journey of human health, the traditional medical diagnosis methods cannot ensure the diagnosis accurate due to the interference of multiple external factors. In response, this paper proposes a multimedia medical management method supported by the data-driven intelligent decision (MMD-DI). This method can be used to predict the survival time of cancer patients under the help of gradient boosting decision tree (GBDT) and hybrid neural network model. First, the feature factors were scanned to match the conditions by GBDT, according to the set value domain; Then the factors were inputted into the neural network. The hybrid neural network was employed to predict the survival time of cancer patients, and it was constructed by combining the convolutional neural network (CNN) and the long short-term memory (LSTM) model. Finally, the stability of the proposed MMD-DI was analyzed, and performance was compared with a series of commonly exploited baseline methods: the mean of cross-validated RMSE (Root Mean Squared Error) evaluation results is 0.183, the mean of cross-validated MAE (Mean Absolute Error) evaluation results is 0.147, the two indicators are both much lower than the commonly exploited baseline methods. A series of experiments proved that MMD-DI has excellent performance and can be used in the multimedia medical management systems. [ABSTRACT FROM AUTHOR]

Intelligent algorithms‐driven industrial decision systems have been a general demand for modeling complex sewage treatment processes (STP). Existing researches modeled complex STP with the use of various neural network models, yet neglecting the fact that latent and occasional relations exist inside complex STP. To deal with the challenge, this paper proposes graph embedding‐based intelligent industrial decision for complex STP (GE‐STP). The graph embedding (GE) scheme is employed to enhance feature extraction and neural computing structure is utilized to simulate uncertain biochemical transformation inside STP. The introduction of GE can not only improves the fineness of feature spaces, but also improves the representative ability of models towards complex industrial processes. On this basis, the GE‐STP is evaluated on a real‐world data set collected from a realistic sewage treatment plant equipped with a set of Internet of Things devices. And some typical neural network models that have been utilized for modeling complex STP, are selected as baseline methods. Three groups of experiments show that efficiency of the GE‐STP exceeds baselines about 6%–12%, and that the GE‐STP is not susceptible to parameter changing. [ABSTRACT FROM AUTHOR]

Background: Chromosomal aneuploidy is the most common birth defect. However, the developmental mechanism and gene expression profile of fetuses with chromosomal aneuploidy are relatively unknown, and the maternal immune changes induced by fetal aneuploidy remain unclear. The inability to obtain the placenta multiple times in real-time is a bottleneck in research on aneuploid pregnancies. Plasma cell-free DNA (cfDNA) carries the gene expression profile information of its source cells and may be used to evaluate the development of fetuses with aneuploidy and the immune changes induced in the mother owing to fetal aneuploidy.Methods: Here, we carried out whole-genome sequencing of the plasma cfDNA of 101 pregnant women carrying a fetus with trisomy (trisomy 21, n = 42; trisomy 18, n = 28; trisomy 13, n = 31) based on non-invasive prenatal testing (NIPT) screening and 140 normal pregnant women to identify differential genes according to the cfDNA nucleosome profile in the region around the transcription start sites (TSSs).Results: The plasma cfDNA promoter profiles were found to differ between aneuploid and euploid pregnancies. A total of 158 genes with significant differences were identified, of which 43 genes were upregulated and 98 genes were downregulated. Functional enrichment and signaling pathway analysis were performed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases found that these signal pathways were mainly related to the coordination of developmental signals during embryonic development, the control of cell growth and development, regulation of neuronal survival, and immune regulation, such as the MAPK, Hippo, TGF-β, and Rap1 signaling pathways, which play important roles in the development of embryonic tissues and organs. Furthermore, based on the results of differential gene analysis, a total of 14 immune-related genes with significant differences from the ImmPort database were collected and analyzed. These significantly different immune genes were mainly associated with the maintenance of embryonic homeostasis and normal development.Conclusions: These results suggest that the distribution characteristics of cfDNA nucleosomes in maternal plasma can be used to reflect the status of fetal development and changes of the immune responses in trisomic pregnancies. Overall, our findings may provide research ideas for non-invasive detection of the physiological and pathological states of other diseases. [ABSTRACT FROM AUTHOR]