Composite Structures Research Articles

Characterization of the Evolution with Temperature of the Structure and Properties of Geopolymer-Cordierite Composites

This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite powder (automotive industry waste) bonded with metakaolin-potassium silicate geopolymer. The principle is that these materials, prepared at temperatures below 100 °C, acquire their final properties during the high-temperature commissioning. The focus is on the influence of the K/Al ratio and cordierite fraction on the stability of the dimensions and porosity during heating at 1000 °C, and on the final Young’s modulus and coefficient of thermal expansion. Conventional and high-temperature XRD evidenced the absence of crystallization of the geopolymer binder and interaction with the cordierite filler during the heating stage when K/Al = 1 or 0.75. By contrast, crystallization of kalsilite and leucite, and diffusion of potassium ions in the structure of cordierite is evidenced for K/Al = 1.5 and 2.3. These differences strongly influence the shrinkage due to sintering and the final properties. It is shown that a K/Al ratio of 0.75 or 1 is favorable to the stability of the porosity, around 25 to 30%. Moreover, a low coefficient of thermal expansion of 4 to 4.5 × 10−6 K−1 and a Young’s modulus of 40 to 45 GPa is obtained.

Two-Dimensional MoSi2N4 Family: Progress and Perspectives Form Theory.

Recently, a new two-dimensional (2D) layered MoSi2N4 has been successfully synthesized by chemical vapor deposition without knowing the 3D counterparts [ Science 2020, 369, 670-674]. The unique septuple-atomic-layer structure and diverse composition of MoSi2N4 have drawn tremendous interest in studying 2D MA2Z4 systems based on the MoSi2N4 structure. As an emerging family of 2D materials, MA2Z4 materials exhibit a wide range of properties and excellent tunability, making them highly promising for various applications. Herein, we summarize recent significant progress in property characterization of the MA2Z4 family. The electronic, magnetic, thermal transport, and superconducting properties, including their tunability through strain engineering and elemental substitution, are presented and elaborated in detail. Further perspectives and new opportunities of the emerging MA2Z4 family are presented at the end of this Perspective.

Exploring Structural and Molecular Features of Sciatic Nerve Lesions in Diabetic Neuropathy: Unveiling Pathogenic Pathways and Targets.

Lesioned fascicles (LF) in the sciatic nerves of individuals with diabetic neuropathy (DN) correlate with clinical symptom severity. This study aimed to characterize the structural and molecular composition of these lesions to better understand DN pathogenesis. Sciatic nerves from amputees with and without type 2 diabetes (T2D) were examined using ex vivo magnetic resonance neurography, in vitro imaging, and proteomic analysis. Lesions were only found in T2D donors and exhibited significant structural abnormalities, including axonal degeneration, demyelination, and impaired blood nerve barrier (BNB). While non-lesioned fascicles from T2D donors showed activation of neuroprotective pathways, lesioned fascicles lacked this response and instead displayed increased complement activation via the classical pathway. The detection of liver-derived acute-phase proteins suggests that BNB disruption facilitates harmful inter-organ communication between the liver and nerves. These findings reveal key molecular mechanisms contributing to DN and highlight potential targets for therapeutic intervention.

NIR-II Fluorescent Nanotheranostics with a Switchable Irradiation Mode for Immunogenic Sonodynamic Therapy.

Nanotheranostics, which integrate diagnostic and therapeutic functionalities, offer significant potential for tumor treatment. However, current nanotheranostic systems typically involve multiple molecules, each providing a singular diagnostic or therapeutic function, leading to challenges such as complex structural composition, poor targeting efficiency, lack of spatiotemporal control, and dependence on a single therapeutic modality. This study introduces NPRBOXA, a nanoparticle functionalized with surface-bound cRGD for targeted delivery to αvβ3/αvβ5 receptors on tumor cells, achieving theranostic integration by sequentially switching its irradiation modes. Under 808nm laser irradiation, NPRBOXA emits NIR-II fluorescence, which aids in identifying the nanoparticle's location and fluorescence intensity, thereby determining the optimal treatment window. Following this, the irradiation mode switches to ultrasound irradiation at the optimal treatment window. Ultrasound irradiation induces NPRBOXA to generate reactive oxygen species, promoting the reduction of OXA-IV to OXA-II, which in turn triggers immunogenic cell death. This mechanism enables a combination of sonodynamic therapy, chemotherapy, and immunotherapy for tumor treatment. The versatile design of NPRBOXA holds promise for advancing precision oncology through enhanced therapeutic efficacy and real-time imaging guidance.

Effect of application of dental varnishes on the properties and chemical composition in irradiated teeth.

To analyze the protective properties of fluor dental varnishes in teeth subjected to radiotherapy. Eighty teeth were irradiated with a single dose of 60Gy. Samples were randomized, and the following groups were made: negative control (n=16); irradiation control (n=16); irradiation + Duraphat (n=16); irradiation + Mi Varnish (n=16); and irradiation + Rivastar (n=16). Energy dispersive x-ray (EDX) analysis and Raman spectrometry were performed to analyze the elemental composition and enamel's chemical structure. The Mi Varnish group presented a lower value (p<.05) in the Ca/F ratio than the other groups. Duraphat group presents differences (p<.05) in the ratio 1070cm1-960cm-1 compared to all the other groups. Based on these in vitro results, the different varnishes used showed a similar preventive effect on the lesions produced by radiotherapy, with none standing out over the others.

Recent advancements in composite materials and structures for energy applications

Recent advancements in composite materials and structures for energy applications

Autonomous intelligent additive manufacturing of continuous fiber-reinforced composites: data-enhanced knowledgebase and multi-sensor fusion

ABSTRACT Additive manufacturing (AM) are an emerging technique to generate complex structures of composite. However, the instability of the AM process leads to adverse manufacturing effects, including dimensional inaccuracies and poor mechanical performance in CFRP composites. Online monitoring and adaptive control based on autonomous cognition are suggested to ensure the accuracy of as-fabricated parts and enhance their quality upon manufacturing. In this study, a method of online monitoring and self-adaptive control based on multi-sensor fusion is proposed to predict and adjust the process parameters during AM of CFRP. The force sensor, visual camera, and thermal camera are employed to obtain the multiple signals upon manufacturing and then realize the autonomous perception, cognition, and decision features. Herein, the quantitative correlations between local defects and multi-sensing features are established to guide the decision-making of closed-loop adjustment. Besides, an empirical surrogate model between the misalignment of fiber bundles and input parameters is built to predict the proper parameters. Moreover, the temperature difference and contact force are selected as the controlled features, which are acquired using a thermal camera and a force sensor. The proposed system offers a novel framework for bolstering both the stability of the AM process and the quality of fabricated components.

Application of Natural (Plant) Fibers Particularly Hemp Fiber as Reinforcement in Hybrid Polymer Composites - Part III. Investigations of Physical and Mechanical Properties of Composites Reinforced with Hemp Fibers

ABSTRACT The article is the third part of a multi-directional analysis of the possibilities, advisability and validity of using natural plant fibers (NPFs) as a reinforcement for polymer structural composites that can be used in the shipbuilding industry in Poland. As a result of the analysis of macroeconomic indicators and natural and non-natural factors regarding NPFs, a representative selection of hemp (Cannabis sativa L.) was made as the raw material to be used to reinforce these composites. Methods and test results are presented enabling comparison of the physical and mechanical properties of the new pro-ecological construction material–hemp fiber reinforced polymer (HFRP), reinforced with fabric made of unmodified and chemically modified hemp fibers.

Characteristics of intestinal microbiota in the acute phase of Kawasaki disease in infants and children

To study the composition, abundance, and functional profiles of the intestinal microbiota in infants and young children with Kawasaki disease (KD) during the acute phase, and to explore the potential role of intestinal microbiota in the pathogenesis of KD. Six children aged 0-3 years with acute KD admitted to the Department of Cardiology, Children's Hospital Affiliated to Capital Institute of Pediatrics from July to October 2021 were prospectively included as the KD group. Six age- and sex-matched healthy children who underwent physical examinations at the hospital during the same period were selected as the healthy control group. Metagenomics sequencing was used to detect and compare the differences in the microflora structure and functional profiles of fecal samples between the two groups. There were significant differences in the structural composition and diversity of intestinal microbiota between the two groups (P<0.05). Compared with the healthy control group, the abundance of Listeria_monocytogenes (family Listeriaceae and genus Listeria), Bifidobacterium_rousetti, Enterococcus_avium, and Enterococcus_hirae was significantly higher in the intestinal microbiota in the KD group (|LDA|>2.0, P<0.05). The steroid degradation and apoptosis pathways were significantly upregulated in the KD group compared with the healthy control group, while the Bacterial_secretion_system, Sulfur_metabolism, Butanoate_metabolism, Benzoate_degradation, β-alanine metabolism, and α-linolenic acid pathways were significantly downregulated (|LDA|>2, P<0.05). There are significant differences in the structure and diversity of intestinal microbiota between children aged 0-3 years with acute KD and healthy children, suggesting that disturbances in intestinal microbiota occur during the acute phase of KD. In particular, Listeria_monocytogenes, Enterococcus_avium, and Enterococcus_hirae may be involved in the pathogenesis of KD through steroid degradation and apoptosis pathways.

Microstructure, phase compositions, and coercivity evolution in micron-thick SmCo-based permanent magnetic films

Permanent magnetic thick films are increasingly used in Micro-Electro-Mechanical Systems (MEMS) devices, but the interplay between magnetic properties, microstructure, and film thickness remains underexplored. We deposited SmCo-based films with thicknesses ranging from 350 nm to 1300 nm using magnetron sputtering at room temperature, followed by in-situ annealing. Our study examined the evolution of microstructure, phase composition, magnetic properties, and domain structures as thickness increases. The films displayed dense, fibrous structures typical of the zone T-type region, with 3D morphologies forming a network structure and an arc-shaped surface that expands with thickness. At thinner levels (around 350 nm), an amorphous SmCo phase predominates, prone to oxidation, while at greater thicknesses, the SmCo5 phase dominates but maintains a grain size of 12–15 nm. Coercivity decreases significantly from 33 kOe to 8 kOe as thickness increases from 630 to 1300 nm due to the diminishing pinning effect and dominance of the reversal domain nucleation mechanism. Analysis using magnetic force microscopy and micromagnetic simulations indicates that this reduction in coercivity is mainly due to the decomposition of the SmCo5 phase and a reduction in magnetic domain size.

Controlling the Depth of Hybridization Chain Reaction by Extended Dangling Ends and Its Analytical Applications.

Hybridization chain reaction (HCR) is a powerful enzyme-free nucleic acid amplification strategy. Triggered by an initiator strand, it yields nicked double helices analogous to alternating copolymers. However, there is no effective way to regulate the HCR reaction, and the most apparent phenomenon is the uncontrollable polymerization of product after introducing an initiator. Here we explore controlling the depth of the HCR reaction by extended dangling ends on hairpin monomers and report that sequence length, nucleotide composition, and secondary structure can alter HCR polymerization and can be utilized for the desired regulation. Interaction dynamics between initiator and hairpin monomers simulated by oxDNA are in good accordance with experimental results. Such a controlling effect can be utilized for new analytical applications that HCR cannot previously achieve, such as analyzing strand-extension enzymes and identifying short-sequence structures. The finding provides a concise but effective way for controlling the depth of HCR reaction and opens the application scope of HCR to more fields.

Определение литологического состава осадочных пород для построения объемной модели по данным ГИС

The features of the lithological composition of productive sediments and their consideration in the petrophysical modeling of a volumetric model based on a GIS complex are considered. It is noted that on the basis of X-ray spectral and granulometric analysis, it is possible to obtain reliable information about the structure, texture, component and mineral composition in order to clarify the petrophysical characteristics of the rocks under study. Using the example of two hydrocarbon deposits “K” and “N” the results of determining the lithological composition of sedimentary rocks from core from different age terrigenous deposits are discussed in order to build a petrophysical model of the entire well section, taking into account the areas of lack of information from direct studies (sludge and core). Electron microscopy and X-ray diffraction analysis are used to study finely dispersed (clay, siliceous, carbonate, etc.) rocks, which are especially important for accurate diagnosis of the mineral composition of rocks. In addition to the features of the geological structure of the deposit, the quantity and quality of the initial information largely determine the methods of constructing the model and the results obtained. The results of X-ray spectral analysis made it possible to determine the composition of chemical elements and the amount of each element in the sample. Information about the mineral composition of rocks and the lithological differences identified at the first stage are distributed to the part of the section where there is no or insufficient information on the core or sludge. The information obtained on the lithological composition of sediments gives the most complete picture of the geological structure of the section opened by the well and is further used as the basis of a volumetric model based on the data of geophysical surveys of GIS wells.

A hierarchical multistage holistic model for acoustic emission source monitoring in composites

Abstract This paper introduces a multistage smart structural health monitoring (SHM) model for carbon-fiber composites, with a focus on multiple types of acoustic emission (AE) source localization and classification. The SHM model uses time-frequency data from various AE events (such as tool drops, impact, and artificial debonding) across different zones of a composite structure. The SHM strategy demonstrates a robust smart monitoring of composites with high accuracy. Further, a hypothesis testing has been carried out that supports the superiority of a 2-stage identification process, revealing statistically significant higher accuracy and confidence intervals across all zones and AE source types. This research establishes a novel framework for solving a hierarchical multistage holistic damage source identification problem, offering robustness in identifying various damage scenarios and quantifying associated prediction uncertainties.&amp;#xD;

Innovative Core–Shell Tubular Structure in Polymer/Manganese–Nickel Oxide/Carbon Nanotube Blends for Electrochemical Components

ABSTRACTTo address the issue of electrochemical performance degradation resulting from redox reactions during the charging and discharging of supercapacitors, we introduced a novel electrode material featuring a core–shell attachment structure (PANI@(MnO2 + NiO)) with the incorporation of carbon nanotubes (CNTs). The introduction of CNT on top of the core–shell structure by a simple chemical synthesis method helps to improve the double‐layer capacitance and Faraday capacitance of the composite. Thus, multiple synergistic effects can be produced to improve charge storage capacity. The morphology structure and electrochemical properties of PANI@(MnO2 + NiO)@CNT were analyzed. In a three‐electrode configuration, the specific capacitance of the composite is 327 F g−1 at a current density of 0.5 A g−1. Remarkably, the capacitance retention rate exceeded 75% after 5000 charge–discharge cycles. Calculations indicate that in a supercapacitor employing a 1 M Na2SO4 electrolyte, the composite demonstrated energy and power densities of 48.1 W h kg−1 and 999.9 W kg−1, respectively. This kind of core–shell structural composites achieved electrochemical properties in line with expectations through a simple chemical synthesis method. As a practical application of supercapacitor electrode materials, PANI@(MnO2 + NiO)@CNT have better electrical properties than similar materials and have broad application prospects in industrial production.

Damage distribution of composite structures of a certain type of aircraft

Aiming at the damage and repair of aircraft composite structures, the applications and damage of composite structures in a certain type of aircraft, including the wing, fuselage and other components, were counted. Solid laminates (integral panels) and sandwich laminates are typical composite structural forms in the aircraft. Structural damage distribution models with time variable were established, and then the damage distributions of the structures were fitted and tested by structural methods. The results show that the quantitative proportions of damage are 75% for skin delamination, 20% for stringer delamination and 4% for stringer debonding. Lognormal distribution, Weibull distribution and Gamma distribution can all be used to fit the geometric parameter distributions of the three types of structural damage, in which the Lognormal distribution model has the best fitting effect. The distribution of structural damage geometric parameters of one aircraft does not vary with time, and the distributions of geometric parameters of the structural damage between the same type aircraft are also highly similar, which can be expressed in a unified function form.

Numerical investigation of thermal influence on debonding behavior in composite structures through a friction and cohesive coupled model

AbstractThis study conducts an in-depth numerical analysis of debonding behavior in composite structures, with a particular focus on the critical role of thermal effects. Utilizing a frictional contact cohesive zone model, the research characterizes the debonding process while sequentially integrating thermal analysis to assess the impact of thermal loading. A thermomechanical coupled model is developed and implemented using the finite element software ABAQUS. The model's accuracy is validated through the Double Cantilever Beam (DCB) test, ensuring reliable results. The methodology involves a detailed finite element analysis, where thermal loads are applied to composite specimens, followed by mechanical loading to simulate debonding. The frictional contact cohesive zone model accurately captures the interface behavior under varying thermal conditions. Quantitative results indicate that thermal loading significantly affects the debonding process, with a noticeable increase in debonding initiation and propagation rates, highlighting the critical influence of thermal effects on structural integrity.

Sex differences in the relationship between body composition and cardiac structure and function.

The purpose of this study was to characterize sex differences in the relationship between body composition and cardiac structure and function. In secondary analyses, we explored pathophysiologic mediators of these relationships. In a cross-sectional analysis of 25,063 UK Biobank participants (54% female, median age 55 years), the sex-specific associations of visceral adipose tissue volume (VAT), appendicular lean mass (ALM), and muscle fat infiltration (MFI) with cardiac magnetic resonance (CMR) measures of cardiac structure and function were assessed using linear regression models. Using causal mediation analysis, 10 biomarkers were explored as mediators of the relationship between adipose depots and cardiac parameters. VAT was associated with increased left ventricular mass (LVM; βwomen = 0.54, βmen = 0.00, pint = 0.01) and wall thickness (βwomen = 0.12, βmen = 0.08, pint<0.001) in women only. A similar sex-specific pattern was observed for MFI effects on LVM (βwomen = 0.44, βmen = 0.03, pint<0.001). ALM was associated with increased LVM and LV volumes in both women and men. In mediation analyses, insulin resistance as measured by triglycerides/high density lipoprotein ratio was a potential partial mediator of VAT effects on chamber dimensions. In the largest and most rigorous analyses of body composition and cardiac parameters to date, we demonstrated that VAT is associated with increased LVM and wall thickness in women but not in men. MFI association with cardiac parameters was similar to VAT, significant in women but not in men.

Fatigue Damage Monitoring of Composite Structures Based on Lamb Wave Propagation and Multi-Feature Fusion

To address the challenges associated with fatigue damage monitoring in load-bearing composite structures, we developed a method that utilizes Lamb wave propagation and partial least squares regression (PLSR) for effective monitoring. Initially, we extracted diverse characteristics from both the time and frequency domains of the Lamb wave signal to capture the essence of the damage. Subsequently, we constructed a PLSR model, leveraging Lamb wave multi-feature fusion, specifically tailored for in-service fatigue damage monitoring. The efficacy of our proposed approach in quantitatively monitoring fatigue damage was thoroughly validated through rigorous standard fatigue tests. In practical applications, our model effectively mitigated the impact of multicollinearity among feature variables on model accuracy. Furthermore, the PLSR model demonstrated superior accuracy compared to the PCR model, given an equal number of principal components. To strike a harmonious balance between efficiency and precision, we optimized the size of the feature variable. The results show that the optimized PLSR model achieved an R-squared value exceeding 97% in predicting the in-service damage area. This underscores the robustness and reliability of our method in accurately monitoring fatigue damage in load-bearing composite structures.

Recent Research on the Optimization of Interfacial Structure and Interfacial Interaction Mechanisms of Metal Matrix Composites: A Review

Interfaces in metal matrix composites (MMCs) are crucial in determining the mechanical properties and functionality of MMCs. This article reviews recent scientific advances and issues related to MMC interfaces from four different perspectives: interfacial structural design, interfacial defect control, thermodynamics and kinetics of interfacial reactions, and interfacial microstructure properties‐based numerical simulation. The influence of interfacial microstructural features on interfacial strength–toughness trade‐offs and their functionality is given special attention. The interfacial problem is still one of the main challenges to be solved in the composite system, which is mainly reflected in the following aspects: interfacial microstructure–deformation mechanisms in complex systems, precise control of interfacial defects and interfacial reaction products, and the efficient and cost‐effective application of numerical simulation techniques. The integrated computation and intelligent design (artificial intelligence) of composites through multiscale computational simulation with the guidance of “interface design‐property prediction” will be the key area of MMC interface research in the future.

Development and Prospect of Space Debris Protection Structures for Spacecraft

Background: As the pace of human conquest of space continues to accelerate, the number of spacecraft carrying out various activities in space continues to increase, so that the available orbital space continues to decrease, the amount of space debris continues to increase, and thus the probability of orbiting spacecraft being impacted by space debris is also increasing. Research on the development of protective structures in the current state is conducive to improving the protection performance of spacecraft protective structures against space debris, reducing the occurrence of spacecraft disintegration events and spacecraft collision events, and may also promote the development of many fields through the development of new technologies. Aim: Through the latest application and development of spacecraft, the advantages and disadvantages of various protection structures are summarized, and the development trend of academic and aerospace protection engineering is analyzed. Methods: Through the latest representative patent research methods for spacecraft space debris, research content, and creative structure, the principle and characteristics of the protective structure are demonstrated. Results: By comparing the application of different spacecraft space debris protection structures, the existing problems of the current protection structures are listed, and the potential development paths and research topics are put forward Conclusion: The development of aerospace, military, and other industries benefit from the development of protective structures, and the composite spacecraft space debris protection structures have broad development prospects.