Search Results (479)

Metamaterial absorbers in terahertz (THz) based bands have garnered significant attention for their potential applications in military stealth, terahertz imaging, and other fields. Nevertheless, the limited bandwidth, low absorption rate, and heavy weight greatly reduce the further development and wide application of terahertz absorbers. To solve these problems, we propose a polystyrene (PS)-based ultra-broadband metamaterial absorber integrated with a polyethylene terephthalate (PET) double-sided adhesive layer and a patterned indium tin oxide (ITO) film through the simulation method, which operates in the THz band. The electromagnetic wave absorption properties and underlying physical absorption mechanisms of the proposed metamaterial absorbers are comprehensively modeled and rigorously numerically simulated. The research demonstrates the metamaterial absorber can achieve absorption performance of over 90% for fully polarized incident waves in the ultra-wideband range of 1.2–10 THz, especially achieving perfect absorption characteristics of over 99.9% near 1.8–1.9 THz and 5.8–6.2 THz. The proposed absorber has a lightweight physical property of 0.7 kg/m² and polarization-insensitive characteristic, and it achieves a broad-angle that allows a range of incidence angles up to 60°. The simulation research results of this article provide theoretical support for the design of terahertz absorbers with ultra-wideband absorption characteristics. Full article

Agricultural nondestructive testing technology is pivotal in safeguarding food quality assurance, safety monitoring, and supply chain transparency. While conventional optical methods such as near-infrared spectroscopy and hyperspectral imaging demonstrate proficiency in surface composition analysis, their constrained penetration depth and environmental sensitivity limit effectiveness in dynamic agricultural inspections. This review highlights the transformative potential of microwave technologies, systematically examining their operational principles, current implementations, and developmental trajectories for agricultural quality control. Microwave technology leverages dielectric response mechanisms to overcome traditional limitations, such as low-frequency penetration for grain silo moisture testing and high-frequency multi-parameter analysis, enabling simultaneous detection of moisture gradients, density variations, and foreign contaminants. Established applications span moisture quantification in cereal grains, oilseed crops, and plant tissues, while emerging implementations address storage condition monitoring, mycotoxin detection, and adulteration screening. The high-frequency branch of the microwave–millimeter wave systems enhances analytical precision through molecular resonance effects and sub-millimeter spatial resolution, achieving trace-level contaminant identification. Current challenges focus on three areas: excessive absorption of low-frequency microwaves by high-moisture agricultural products, significant path loss of microwave high-frequency signals in complex environments, and the lack of a standardized dielectric database. In the future, it is essential to develop low-cost, highly sensitive, and portable systems based on solid-state microelectronics and metamaterials, and to utilize IoT and 6G communications to enable dynamic monitoring. This review not only consolidates the state-of-the-art but also identifies future innovation pathways, providing a roadmap for scalable deployment of next-generation agricultural NDT systems. Full article

Lattice-based metamaterials have attracted much attention due to their excellent mechanical properties. Nevertheless, designing lattice materials with desired properties is still challenging, as their mesoscopic topology is extremely complex. Herein, the bidirectional evolutionary structural optimization (BESO) method is adopted to design lattice structures with maximum bulk modulus and elastic isotropy. Various lattice configurations are generated by controlling the filter radius during the optimization processes. Afterwards, the optimized lattices are fabricated using Stereo Lithography Appearance (SLA) printing technology. Experiments and numerical simulations are conducted to reveal the mechanical behavior of the topology-optimized lattices under quasi-static compression, which are compared with the traditional octet-truss (OT) and body-centered cubic (BCC) lattice structures. The results demonstrate that the topology-optimized lattices exhibited superior mechanical properties, including modulus, yield strength, and specific energy absorption, over traditional OT and BCC lattices. Moreover, apart from the elastic modulus, the yield stress and post-yield stress of the topology-optimized lattice structures with elastically isotropic constraints also present lower dependence on the loading direction. Accordingly, the topology optimization method can be employed for designing novel lattice structures with high performance. Full article

Background and Objectives: The relationship between ABO or Rh blood groups and susceptibility to Chikungunya virus (CHIKV) infection remains unclear. This systematic review and meta-analysis aimed to synthesize available evidence on this association. Materials and Methods: Studies reporting ABO and/or Rh blood groups and CHIKV infection were searched through PubMed, Scopus, EMBASE, MEDLINE, Ovid, ProQuest, and Google Scholar up to 8 July 2025. A random-effects meta-analysis was conducted to calculate pooled odds ratios (Ors) with 95% CIs. Heterogeneity was assessed using I² statistics. Subgroup analyses were performed based on study design and study quality. Sensitivity analysis was conducted using a leave-one-out method. Publication bias was evaluated via funnel plots and Egger’s test. Results: Seven studies, including 24,828 participants, were included. No significant associations were observed between blood groups A, B, AB, or Rh(D) and CHIKV infection. However, blood group O was significantly associated with an increased risk of CHIKV infection (OR: 1.52, 95% CI: 1.01–2.29, p = 0.043, I² = 95.38%) compared to non-O blood groups. Subgroup analyses showed stable results. Nevertheless, the sensitivity analysis indicated that certain studies had a greater influence on the overall results. In addition, significant publication bias was also detected. Conclusions: Current evidence indicates that blood group O is significantly associated with an increased susceptibility to CHIKV infection. In contrast, no consistent associations were observed for other ABO or Rh blood groups. Due to substantial heterogeneity and methodological limitations, these findings should be interpreted with caution. Further well-designed, large-scale studies with standardized diagnostics are needed to clarify these associations and underlying mechanisms. Full article

Addressing the urgent need for lightweight and reusable energy-absorbing materials in aviation impact resistance, this study introduces an innovative multi-directional braided metamaterial design enabled by 4D printing technology. This approach overcomes the dual challenges of intricate manufacturing processes and the limited functionality inherent to traditional textile preforms. Six distinct braided structural units (types 1–6) were devised based on periodic trigonometric functions (Y = A sin(12πX)), and integrated with shape memory polylactic acid (SMP-PLA), thereby achieving a synergistic combination of topological architecture and adaptive response characteristics. Compression tests reveal that reducing strip density to 50–25% (as in types 1–3) markedly enhances energy absorption performance, achieving a maximum specific energy absorption of 3.3 J/g. Three-point bending tests further demonstrate that the yarn amplitude parameter A is inversely correlated with load-bearing capacity; for instance, the type 1 structure (A = 3) withstands a maximum load stress of 8 MPa, representing a 100% increase compared to the type 2 structure (A = 4.5). A multi-branch viscoelastic constitutive model elucidates the temperature-dependent stress relaxation behavior during the glass–rubber phase transition and clarifies the relaxation time conversion mechanism governed by the Williams–Landel–Ferry (WLF) and Arrhenius equations. Experimental results further confirm the shape memory effect, with the type 3 structure fully recovering its original shape within 3 s under thermal stimulation at 80 °C, thus addressing the non-reusability issue of conventional energy-absorbing structures. This work establishes a new paradigm for the design of impact-resistant aviation components, particularly in the context of anti-collision structures and reusable energy absorption systems for eVTOL aircraft. Future research should further investigate the regulation of multi-stimulus response behaviors and microstructural optimization to advance the engineering application of smart textile metamaterials in aviation protection systems. Full article

Prefabricated buildings, known for their energy efficiency, environmental benefits, and industrial advantages, play a crucial role in urban renewal. Previous studies on the carbon emissions of prefabricated buildings mainly concentrate on the assessment and auditing of carbon emissions at the materialization and construction phase. Few of them have analyzed the carbon emissions at the operational phase or the influence mechanisms of prefabricated buildings on carbon emissions in urban renewal. Thus, this paper explored the factors and mechanisms that influence carbon emissions in prefabricated buildings in China’s urban renewal. Firstly, the factors that influence the carbon emissions of prefabricated buildings in China’s urban renewal were identified through meta-analysis. Secondly, the theoretical model was developed to illustrate the influence paths of prefabricated buildings on the carbon emissions of urban renewal. Finally, the structural equation model (SEM) was used to test the hypotheses in the theoretical model using data collected from questionnaires. The results show that the carbon emission reduction potential of prefabricated buildings is influenced by four aspects, namely, socioeconomic factors, policy regulations, building operation, and materialization. Policy regulations have the greatest impact on the carbon emissions of prefabricated buildings. They not only directly affect the carbon emissions of urban renewal but also influence carbon emissions indirectly through the social economy aspect. The direct impact of social economy on the carbon emissions of prefabricated buildings is insignificant, while it can indirectly affect the carbon emission reduction in prefabricated buildings by influencing building operations and the materialization stage. The findings could help provide strategies for prefabrication and enhance the reduction potential of urban renewal. Full article

Acoustic metamaterials (AMs) are artificially structured materials composed of subwavelength units that enable acoustic phenomena not achievable with conventional materials and structures. This review defines and presents a distinct category referred to as soft acoustic metamaterials (SAMs), which use soft materials or reconfigurable structures to achieve enhanced acoustic functionality. These systems make use of the inherent flexibility of their materials or the deformability of their geometry to support passive, active, and adaptive functions. To capture this structural and functional diversity, we introduce a three-dimensional classification that considers geometry, acoustic control mechanisms, and functional responsiveness as interrelated aspects. The geometry is classified into two-dimensional metasurfaces and three-dimensional bulk structures. The control mechanisms include local resonance, phase modulation, attenuation, and structural reconfiguration. The response type refers to whether the system behaves passively, actively, or adaptively. Using this approach, we provide an overview of representative implementations and compare different design approaches to highlight their working principles and application areas. This review presents a structured classification for soft acoustic metamaterials and offers a foundation for future research, with broad potential in intelligent sound systems, wearable acoustics, and architectural applications. Full article

This work focuses on characterizing structured metamaterials by assessing their elastic law and ultimate strength using finite elements and limit analysis applied to a representative volume element. The elastic and plastic behavior of a reference geometry—the octet truss lattice—is obtained by calculating the response of the representative volume element subjected to prescribed tensor strain bases, namely pure normal strain and pure shear, along the cube symmetry directions. The geometry of the body centered cubic and pure cubic phases of the representative volume element has been analyzed, highlighting that the elastic isotropic behavior depends on the ratio between the stiffnesses of the two phases. The ultimate behavior of the structure has been analyzed through the direct application of the lower bound method of limit analysis. The method has been implemented in a direct finite element environment using the limit analysis procedure developed by the authors. The method was already used and described in previous publications and is briefly recalled. It is based on the identification of the linear operator linking the self-equilibrated stress set to a discrete parameter manifold, accounting for the piecewise continuous distribution of the permanent strain. In the paper, it is highlighted that for different aspect ratios between the body-centered cubic and the pure cubic phase geometry, different ratios between limit shear stress and normal stress arise, the isotropic one assumed to coincide with the von Mises result, where ${\displaystyle \frac{{\sigma }_0}{{\tau }_0}}=\sqrt{3}$. Full article

Multi-stable mechanical metamaterials based on the snap-through behavior of cosine beams have been shown to have significant potential in the field of capacity absorption due to their advantages such as reusability and structural simplicity. However, traditional multi-stable metamaterials have exhibited limitations in both energy absorption and trapping ability. Inspired by the bionic multilevel structure, a novel hierarchical multi-stable cylindrical structure (HMCS) based on cosine curved beams is proposed. We investigated the snap-through behaviors and energy absorption capacity of the HMCS. Both finite element simulation results and experimental results show that the hierarchical multi-stable structure exhibits excellent specific energy absorption and energy trapping capabilities compared to traditional multi-stable cylindrical structures (TMCSs). Furthermore, by analyzing the effect of height h and thickness t on the snap-through behavior of the structure, the key parameters determining the mono-stable or bi-stable response are identified. In addition, a gradient-based study of the structure reveals the dominant role of stiffness in the snap-through behavior of multilayer structures. This work provides insights into the application of multi-stable cylindrical structures in energy trapping and absorption and offers a new strategy for designing high-efficiency energy-absorbing metamaterials. Full article

Background and Objectives: Sarcopenia and lower urinary tract symptoms (LUTSs) are both prevalent among older adults and may share underlying pathophysiological mechanisms. However, their association has not been systematically quantified. This systematic review and meta-analysis aimed to evaluate the association between sarcopenia and LUTSs, including the pooled estimates of prevalence and odds ratios (ORs), and to explore the influence of diagnostic definitions and study-level factors. Materials and Methods: A comprehensive literature search was conducted using PubMed and Embase for studies published between 1 January 2000 and 26 April 2025. This study adhered to PRISMA and MOOSE guidelines and was registered in PROSPERO (CRD420251037459). Eligible observational studies reported LUTS prevalence or ORs in individuals with sarcopenia, low muscle strength (LMS), low lean mass (LLM), low gait speed (LGS), or sarcopenia risk identified by SARC-F (score ≥4). Pooled ORs and prevalence rates were calculated using a random-effects model. Subgroup analyses were performed based on sarcopenia definitions—Asian Working Group for Sarcopenia (AWGS) and European Working Group on Sarcopenia in Older People (EWGSOP)—as well as LUTS subtypes and diagnostic components. Univariate meta-regression assessed associations with age, BMI, sex distribution, WHO region, and risk of bias. Results: Twenty-five studies comprising 84,484 participants were included. Sarcopenia was significantly associated with LUTSs (pooled OR = 1.78; 95% CI: 1.29–2.45; p < 0.001), with a pooled LUTS prevalence of 43.2% (95% CI: 26.9–61.0%). Stronger associations were observed in studies using AWGS diagnostic criteria (OR = 2.24; 95% CI: 1.41–3.56; p = 0.001), in those evaluating severe sarcopenia (OR = 1.66; 95% CI: 1.03–2.68; p = 0.038), and in institutionalized populations (OR = 3.68; 95% CI: 2.18–6.24; p < 0.001) compared to community-dwelling populations (OR = 1.43; 95% CI: 1.06–1.92; p = 0.018). Sarcopenia risk identified by SARC-F (score ≥4) showed the strongest association with LUTSs (OR = 3.20; 95% CI: 1.92–5.33; p < 0.001). Significant associations were also found for LLM (OR = 1.52; 95% CI: 1.19–1.95; p = 0.001) and LGS (OR = 1.37; 95% CI: 1.06–1.76; p = 0.015), but not for LMS (OR = 0.94; 95% CI: 0.47–1.89; p = 0.871). Exploratory analyses comparing LLM diagnostic modalities—including standardized criteria (ASMI, ASM/BMI), imaging-based methods (SMI, PMA), and surrogate measures (calf circumference)—revealed no significant differences (all p > 0.05). Heterogeneity was high (I² > 90%). Egger’s test indicated no evidence of publication bias (p = 0.838), and trim-and-fill analysis did not affect the pooled estimates. Conclusions: Sarcopenia—particularly in its severe forms—is significantly associated with LUTSs. Additionally, individuals who screened positive for sarcopenia using the SARC-F tool demonstrated a heightened risk of LUTSs. Subgroup analyses revealed a stronger association in institutionalized populations, suggesting that care setting may modify risk. These findings underscore the importance of assessing muscle health in older adults with urinary symptoms. Standardization of diagnostic criteria and longitudinal studies are needed to clarify causality and guide targeted interventions. Full article

High-Bandwidth Memory (HBM) enables the bandwidth required by modern AI and high-performance computing, yet its three dimensional stack traps heat and amplifies thermo mechanical stress. We first review how conventional solutions such as heat spreaders, microchannels, high density Through-Silicon Vias (TSVs), and Mass Reflow Molded Underfill (MR MUF) underfills lower but do not eliminate the internal thermal resistance that rises sharply beyond 12layer stacks. We then synthesize recent hybrid bonding studies, showing that an optimized Cu pad density, interface characteristic, and mechanical treatments can cut junction-to-junction thermal resistance by between 22.8% and 47%, raise vertical thermal conductivity by up to three times, and shrink the stack height by more than 15%. A meta-analysis identifies design thresholds such as at least 20% Cu coverage that balances heat flow, interfacial stress, and reliability. The review next traces the chain from Coefficient of Thermal Expansion (CTE) mismatch to Cu protrusion, delamination, and warpage and classifies mitigation strategies into (i) material selection including SiCN dielectrics, nano twinned Cu, and polymer composites, (ii) process technologies such as sub-200 °C plasma-activated bonding and Chemical Mechanical Polishing (CMP) anneal co-optimization, and (iii) the structural design, including staggered stack and filleted corners. Integrating these levers suppresses stress hotspots and extends fatigue life in more than 16layer stacks. Finally, we outline a research roadmap combining a multiscale simulation with high layer prototyping to co-optimize thermal, mechanical, and electrical metrics for next-generation 20-layer HBM. Full article

Background and Objectives: Periodontitis is an inflammatory disease that compromises the supporting structures of the teeth, leading to irreversible tissue damage and tooth loss. While subgingival professional mechanical plaque removal (PMPR) remains the gold standard treatment, there is increasing interest in adjunctive therapies. Platelet-rich fibrin (PRF) has gained attention as a promising biomaterial to enhance periodontal healing and regeneration. This study aimed to evaluate the clinical and immunological effectiveness of PRF as an adjunct to PMPR. Materials and Methods: Clinical studies published between January 2019 and August 2024 were included from the ProQuest, PubMed, PMC, ScienceDirect, Scopus, and EBSCO databases. Seven studies met the inclusion criteria, focusing on adults with periodontitis treated with PRF + PMPR compared to PMPR alone. Primary outcomes included changes in clinical and immunological parameters. Risk of bias was assessed using the Cochrane ROB2 tool. Meta-analysis was conducted using both fixed-effect and random-effects models, depending on heterogeneity. Results: The meta-analysis demonstrated significant improvements in clinical outcomes in the PRF + PMPR group, with reductions in probing pocket depth (SMD: −1.43 mm; 95% CI: −2.05 to −0.81; p < 0.00001), clinical attachment level (SMD: −1.34 mm; 95% CI: −1.95 to −0.73; p < 0.0001), bleeding on probing (SMD: −0.75 mm; 95% CI: −1.11 to −0.39; p < 0.00001), gingival recession (SMD: −0.79 mm; 95% CI: −1.33 to −0.25; p = 0.004), and gingival index (SMD: −0.82 mm; 95% CI: −1.37 to −0.28; p = 0.003). Favorable trends were also observed in IL-10, TGF-β, VEGF, PDGF-BB, periostin, and type I collagen levels. Conclusions: PRF enhances clinical and immunological outcomes and supports periodontal tissue stability when used as an adjunct to non-surgical therapy. Full article

Background and Objectives: The Epstein-Barr virus (EBV) belongs to the gamma herpesviruses family. Evidence from the literature suggests that EBV initiates immune responses and the production of antibodies. Chronic or recurrent EBV infections may be associated with autoimmune diseases such as systemic lupus erythematosus, Sjögren’s syndrome, rheumatoid arthritis, multiple sclerosis, or inflammatory bowel diseases. This review aims to establish the role of EBV in the development and progression of autoimmune diseases. Materials and Methods: A literature search was conducted using PubMed, PMC, Google Scholar, and SCOPUS. Relevant studies, including meta-analyses, case-control studies, literature reviews, cross-sectional studies, and longitudinal studies, were identified through titles and abstracts screening for a comprehensive analysis. Results: Our study revealed a strong association between EBV infection and several autoimmune diseases, including multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. Epstein-Barr virus seropositivity was significantly higher in affected individuals. Elevated EBV-specific antibodies correlated with disease onset and severity. EBV DNA and latency proteins were detected in diseased tissues, alongside immune dysregulation and molecular mimicry mechanisms. Conclusions: Our findings highlight that EBV may be an important factor in autoimmune disease pathogenesis, contributing to immune activation and tissue damage. Further research is needed to explore EBV-targeted therapies and their potential in preventing or managing autoimmune diseases. Full article

Terahertz metamaterial dual-band absorbers are used for multi-target detection and high-sensitivity sensing in complex environments by enhancing information that reflects differences in the measured substances. Traditional design processes are complex and time-consuming. Machine learning-based methods, such as neural networks and deep learning, require a large number of simulations to gather training samples. Existing design methods based on single-objective optimization often result in uneven multi-objective optimization, which restricts practical applications. In this study, we developed a metamaterial absorber featuring a circular split-ring resonator with four gaps nested in a “卍” structure and used the Multi-Objective Firefly Algorithm based on Multiple Cooperative Strategies to achieve fast optimization of the absorber’s structural parameters. A comparison revealed that our approach requires fewer iterations than the Multi-Objective Particle Swarm Optimization and reduces design time by nearly half. The absorber designed using this method exhibited two resonant peaks at 0.607 THz and 0.936 THz, with absorptivity exceeding 99%, indicating near-perfect absorption and quality factors of 31.42 and 30.08, respectively. Additionally, we validated the absorber’s wave-absorbing mechanism by applying impedance-matching theory. Finally, we elucidated the resonance-peak formation mechanism of the absorber based on the surface current and electric-field distribution at the resonance frequencies. These results confirmed that the proposed dual-band metamaterial absorber design is efficient, representing a significant step toward the development of metamaterial devices. Full article

Background and Objectives: Pulmonary function is a key outcome in scoliosis management, as both the condition and its treatments can impact respiratory mechanics. This systematic review aimed to assess the effects of scoliosis interventions on pulmonary function, focusing on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF). Materials and Methods: A comprehensive literature search was conducted in PubMed, Web of Science, Scopus, and the Cochrane Library to identify studies evaluating pulmonary function before and after scoliosis treatment. Data on respiratory parameters, intervention types, and follow-up periods were extracted. Meta-analyses were performed using standardized mean differences (SMDs) with 95% confidence intervals (CIs). Heterogeneity was assessed using the I² statistic. Results: The meta-analysis revealed no significant overall effect of scoliosis interventions on FVC or FEV1. For FVC, the pooled effect size was 0.0126 (95% CI: −0.0161 to 0.0413; p = 0.3728), and for FEV1, it was 0.0034 (95% CI: −0.0452 to 0.0519; p = 0.8869). Heterogeneity was minimal (I² = 0.0%) for both metrics. Individual studies showed variability: some reported increases in FVC and FEV1 by over 1.5 L, while others observed decreases in percent predicted values and absolute volumes. PEF generally improved, with some interventions showing statistically significant gains (p < 0.001). Conclusions: Non-invasive rehabilitation methods, such as breathing exercises and aquatic therapy, were associated with more consistent improvements in pulmonary function. In contrast, the effects of surgical interventions were variable and often not statistically significant. These findings suggest a promising role for conservative therapies in enhancing long-term respiratory outcomes in scoliosis patients, though further high-quality research is warranted. Full article