Three-layered Composite Structure Research Articles

A novel complex-high-order graph convolutional network paradigm: ChyGCN

Abstract In recent years, there has been a growing interest in Graph Convolutional Networks (GCN). However, existing GCN and variants are predominantly based on simple graph or hypergraph structures, which restricts their ability to handle complex data correlations in practical applications. These limitations stem from the difficulty in establishing multiple hierarchies and acquiring adaptive weights for each of them. To address this issue, this paper introduces the latest concept of complex hypergraphs and constructs a versatile high-order multi-level data correlation model. This model is realized by establishing a three-tier structure of complexes-hypergraphs-vertices. Specifically, we start by establishing hyperedge clusters on the foundational network, utilizing a second-order hypergraph structure to depict potential correlations. For this second-order structure, truncation methods are applied to assess and generate a three-layer composite structure. During the construction of the composite structure, an adaptive learning strategy is implemented to merge correlations across different levels. We evaluate this model on several popular datasets and compare it with recent state-of-the-art methods. The comprehensive assessment results demonstrate that the proposed model surpasses existing methods, particularly in modeling implicit data correlations (the classification accuracy of nodes on five public datasets Cora, Citeseer, Pubmed, Github Web ML, and Facebook is 86.1±0.33, 79.2±0.35, 83.1±0.46, 83.8±0.23, and 80.1±0.37, respectively). This indicates that our approach holds advantages when handling datasets with implicit multi-level structures.

Customized triphasic cartilage composite scaffold simulating hypoxic microenvironment for osteochondral regeneration

The regeneration of the osteochondral complex in situ presents a significant challenge. The inherent hypoxic microenvironment of cartilage plays a critical role in facilitating osteochondral repair. The successful regeneration of the osteochondral complex necessitates the utilization of materials and structures that closely mimic its composition. In this study, carboxymethyl chitosan (CCS), oxidized hyaluronic acid (OHA), and tannic acid (Ta) were employed to fabricate an injectable and self-healing hydrogel (Ta@gel). The incorporation of Ta within the hydrogel network enables preferential oxidation, thereby creating an anoxic microenvironment within the hydrogel. Bone marrow-derived mesenchymal stem cells (BMSCs) were encapsulated within microspheres composed of methacrylic anhydride gelatin (GelMA). These microspheres were subsequently loaded into a Ta@gel. The resulting bionic hydrogel composite was then combined with a three-dimensional (3D) printed hydroxyapatite (HAp) scaffold coated with poly-l-lysine (PLL). This combination resulted in the formation of a bionic three-layer composite structure (HAp@PLL + Ta@gel + GelMA@BMSCs) that closely resembles the complex composition and structure of natural osteochondral complex. The efficacy of this customized triphasic composite scaffold in promoting osteochondral complex regeneration has been demonstrated in vitro and in vivo. Consequently, this study provided a new sight for inducing the in situ regeneration of cartilage.

Mechanism study of composite co-deposited Cu/Co-Mo corrosion-resistant coating on 6061 Al alloy

To improve the bonding strength of the 6061 Al alloy with the plating layer and enhance the corrosion resistance, a Cu/Co-Mo corrosion-resistant plating layer was deposited on its surface. Through Scanning Electron Microscope, it is found that Cu/Co-Mo and the substrate can form an obvious three-layer composite structure, and X-ray diffraction detects that the CoMo coating is an alloy with obvious amorphous characteristics, and its phase composition is Co3Mo. After performance testing, the composite coating improved the corrosion resistance and hardness of the substrate and could play a good role in protecting the 6061 Al alloy. In addition, the mechanism of induced codeposition of CoMo alloy was investigated, and the deposition of Mo6+ was determined by cyclic voltammetry to be a three-step six-electron irreversible reduction reaction. Chronopotentiometry revealed that Mo6+ underwent a diffusion-controlled transient nucleation process. The AC impedance indicated that the selection of a suitable voltage is beneficial to reduce the hydrogen precipitation reactions during electrodeposition.

The erosion-corrosion behaviors of the full-scale Ni-P and Ni-Cu-NiW internal coating tubing

In the present work, a self-built device called the “full scale tubular goods erosion-corrosion test system” was used to investigate the erosion-corrosion behavior of Ni-P and Ni-Cu-NiW internal coating tubing in a simulated operating condition of a water injection well in the Xinjiang oil field, China. The tubing, with a total length of 10 m, was tested under accelerated conditions. The erosion-corrosion performance was evaluated using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results showed that the Ni-P coating experienced severe corrosion, including internal cracking and peeling. The corrosion failure of the Ni-P coating was mainly attributed to the presence of defects such as pores and the penetration and self-catalysis of chloride ions. On the other hand, the Ni-Cu-NiW coating exhibited excellent corrosion resistance due to its three-layer composite structure and the addition of tungsten (W), which enhanced its resistance to chloride ion penetration.

Novel EPE co-extruded encapsulating films with UV down-conversion power gain effect for highly efficient solar cells

How to maintain or even improve the performance of solar cells under the influence of high temperature, high humidity and intense ultraviolet light has always been a challenging research topic. Here, we propose a novel and effective solution by combining the benefits of EVA (ethylene vinyl acetate), POE (polyolefin) and UV down-conversion (UV-DC) fluorescent nanomaterial (Sr2-xMgSi2O7-x: Eu2+, Dy3+) to construct the first commercially available UV-DC EPE co-extruded encapsulating film with a three-layer composite structure. On the one hand, the UV-DC EPE incorporates the high adhesive strength of EVA and the strong weather resistance of POE. On the other hand, the UV-DC EPE can also convert the UV irradiation, inefficient for power generation and easily cause damage to solar cells, into visible light range with high quantum efficiencies. Therefore, we discover that the UV-DC EPE not only shows higher stability than other encapsulation films under potential-induced degradation (PID), pressure cooker test (PCT), UV and natural sunlight aging tests, but also enhances the power generation efficiencies by 0.3% and 2.3% compared with the UV-transmitting and the UV-filtering EPE films, respectively. The progress in this work breaks the stereotypical definition of encapsulation that only slows down attenuation, but integrates the advantages of power gain effect, high stability, and low cost into the novel encapsulation material and technology, which is expected to be promoted and industrialized in the near future.

Hollow polyester/kapok/hollow polyester fiber-based needle punched nonwoven composite materials for rapid and efficient oil sorption.

Nowadays oil pollution poses a serious threat to the environment and people's daily life. As reusable and environmentally friendly materials, fiber-based oil sorption materials can effectively alleviate this phenomenon. However, maintaining a high sorption rate along with improved mechanical properties remains a challenge for oil sorption materials. Herein, we report a novel hollow PET/kapok/hollow PET nonwoven with high porosity and oil retention, outstanding cyclic oil sorption rate and improved mechanical performance using kapok as the oil preserver and hollow PET as the conductor and structure enhancer. Benefiting from the three-layer composite structure fabricated by carding and needle punching reinforcement, the resulting oil sorption materials, with kapok proportion more than or equal to 60%, exhibited high oil sorption rate and oil sorption speed. The materials of 20HP/60K/20HP component content present a high initial oil sorption rate of 28.22 g g-1, a maximum oil sorption rate of 31.17 g g-1 and a sorption rate constant of the Quasi second-order kinetic equation of 0.067 in plant oil. On the other hand, when the proportion of kapok fiber in the material was below 60%, due to the introduction of hollow PET, the mechanical properties were significantly boosted, and its oil retention and reusability were distinguished, with a reuse rate stabilizing at a relatively high level (>93%) in plant oil after undergoing three oil sorption cycles. The successful fabrication of hollow PET/kapok/hollow PET nonwovens could provide a new approach for the design and development of oil sorption materials.

Prediction of the Sound Absorption Coefficient of Three-Layer Aluminum Foam by Hybrid Neural Network Optimization Algorithm

The combination of multilayer aluminum foam can have high sound absorption coefficients (SAC) at low and medium frequencies, and predicting its absorption coefficient can help the optimal structural design. In this study, a hybrid EO-GRNN model was proposed for predicting the sound absorption coefficient of the three-layer composite structure of the aluminum foam. The generalized regression neural network (GRNN) model was used to predict the sound absorption coefficient of three-layer composite structural aluminum foam due to its outstanding nonlinear problem-handling capability. An equilibrium optimization (EO) algorithm was used to determine the parameters in the neuronal network. The prediction results show that this method has good accuracy and high precision. The calculation result shows that this proposed hybrid model outperforms the single GRNN model, the GRNN model optimized by PSO (PSO-GRNN), and the GRNN model optimized by FOA(FOA-GRNN). The prediction results are expressed in terms of root mean square error (RMSE), absolute error, and relative error, and this method performs well with an average RMSE of only 0.011.

Sound absorption properties of nanofiber membrane-based multi-layer composites

Aiming at the problem of poor low-frequency sound absorption performance of traditional fiber sound-absorbing materials, this work prepared nanofiber membrane-based multi-layer composites by lamination for sound absorption and noise reduction. By laminating polyvinyl butyral (PVB) nanofiber membrane with polyester (PET) fiber felt and polyurethane (TPU) film, bi-layer and three-layer composites structure sound-absorbing materials were manufactured, and the effect of lamination sequence and thickness of each layer on their sound absorption performance were investigated. The results testified that the composite structures have excellent sound absorption performance in low-frequency range while the nanofiber membrane was placed at the sound-facing surface. When the thickness of PVB was 2 mm, and the thickness of PET was 10 mm, the average sound absorption coefficient of PVB-PET structure composite reached 0.5646 in the low-frequency range. Notably, the frequency and peak of the first resonance sound absorption peak were 396 Hz and 0.8529, respectively, which can meet the needs of sound absorption and noise reduction. Another layer of TPU film was compounded on the backside of this structure, and the sound absorption peak was further transferred to the low-frequency range. The frequency and peak of the first resonance sound absorption peak of the three-layer composite structure material were 300 Hz and 0.7772, respectively. Compared to 10 mm thick PET fiber felts, the average sound absorption coefficients of both bi-layer and three-layer composite materials were improved by more than 200 % in the range of 100–1000 Hz. Additionally, the results of response surface optimization illuminated that the sound absorption of different frequency bands can be targeted through reasonable selection and optimization of structural parameters.

A biomimetic three-layered fibrin gel/PLLA nanofibers composite as a potential scaffold for articular cartilage tissue engineering application

Developing an engineered scaffold inspired by structural features of healthy articular cartilage (AC) has attracted much attention. In this study, the design and fabrication of a three-layered fiber/hydrogel scaffold in which each layer replicates the organization of a pertinent layer of AC tissue is aimed. To this end, electrospun poly-L-lactic acid (PLLA) nanofibers are prepared and fragmented into nano/micro cylinders via aminolysis. Three-layers of the scaffold, a fibrin coated fibrous layer, a fibrin gel (FG) layer incorporating chopped fibers and a FG embedding cylindrical aligned fibrous mat perpendicular to articulating surface, respectively served as an upper, middle and bottom layers, are prepared. The layers’ physicomechanical characteristics are comprehensively evaluated. Results show that optimized electrospinning set up results in the smallest fibers diameter of 367 ± 317 nm and successful aminolysis provides amine-functionalized chopped nanofibers with a mean length of 1.46 ± 0.9 µm. Static mechanical analysis of the layers demonstrates that tensile Young’s modulus of the upper layer is 152 ± 17 MPa while compressive moduli of the middle and bottom layers are 9.8 ± 3.8 and 25.3 ± 5.2 KPa, respectively and the compressive modulus of three-layered scaffold is 13.7 ± 2.5 KPa. Assessing mechanical parameters under dynamic loading also shows that adding fibrous part in the composite scaffold layers enhances viscoelastic behavior of FG. Also, incorporation of 0.25% chopped fibers into the fibrin matrix notably enhances the equilibrium water content; however, it increases in-vitro weigh loss rate from 6% to 10.5% during a seven-day period. Cytocompatibility analysis confirms that all layers possess acceptable cytocompatibility. In a conclusion, the designed three-layered composite structure successfully mimics the physicomechanical as well as microstructural features of AC and could be suggested as a potential scaffold for this tissue regeneration.

One-step hydrothermal synthesis of 2,5-PDCA-containing MgAl-LDHs three-layer composite coating with high corrosion resistance on AZ31

The addition of 2,5-pyridinedicarboxylic acid (2,5-PDCA) to the Mg-Al LDH coating, which was prepared by one-step hydrothermal synthesis, had extremely enhanced the corrosion protection of AZ31 Mg alloy, although the 2,5-PDCA could not be intercalated into the interlayer spacing. The corrosion current density of 0.05 mol L−1 2,5-PDCA LDH containing LDH coating is 3.18 nA cm−2, reduced by two orders of magnitude compared to the LDH coating without inhibitor, and the corrosion inhibition efficiency of the coating is 98.05%. The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers. The innermost layer is a thick layer that consists of Mg(OH)2 and the intermediate layer is LDH, which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg. This kind of sediment/LDH/Mg(OH)2 three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy.

Artificial vascular implants with unidirectional drug release and mechanical properties imitating natural blood vessels

Small-diameter artificial vessels require a combination of a range of material properties, including high strength, compliance, sutureability, and kink resistance in specific situations. We combined electrospinning technology with thermally induced separation technology to prepare composite three-layer artificial vessels using a PCL/gelatin co-blended material and a hybrid hydrogel enhanced gel structure to achieve high strength, flexibility and kink resistance, as well as excellent water tightness. The electrospun fibers in the artificial vessel provide mechanical stability, while the gelatin blended material enhances hydrophilicity. The results show that the three-layer composite structure is well bonded together, provides sufficient rupture strength and sutureability, and exhibits arterial-like compliance and resistance to kinking. The hydrogel layer drug release rate can also be adjusted by adjusting the PCL/gelatin co-blended layer ratio. This composite vascular scaffold is expected to play an important role in tissue engineering.

The eggshell membrane: A potential biomaterial for corneal wound healing.

The eggshell membrane (ESM) is an abundant resource with innate complex structure and composition provided by nature. With at least 60 million tonnes of hen eggs produced globally per annum, utilisation of this waste resource is highly attractive in positively impacting sustainability worldwide. Given the morphology and mechanical properties of this membrane, it has great potential as a biomaterials for wound dressing. However, to date, no studies have demonstrated nor reported this application. As such, the objective of this investigation was to identify and optimise a reproducible extraction protocol of the ESM and to assess the physical, chemical, mechanical and biological properties of the substrate with a view to use as a wound dressing. ESM samples were isolated by either manual peeling (ESM-strip) or via extraction using acetic acid [ESM-A0.5] or ethylenediaminetetraacetic acid, EDTA [ESM-E0.9]. Energy dispersive X-ray spectroscopy (EDS) confirmed that there were no traces of calcium residues from the extraction process. Fourier transform infrared (FTIR) spectroscopy revealed that the extraction method (acetic acid and EDTA) did not alter the chemical structures of the ESM and also clarified the composition of the fibrous proteins of the ESM. Scanning electron microscopy (SEM) analyses revealed a three-layer composite structure of the ESM: an inner layer as continuous, dense and non-fibrous (limiting membrane), a middle layer with a network of fibres (inner shell membrane) and the outer layer (outer shell membrane) of larger fibres. Material properties including optical transparency, porosity, fluid absorption/uptake, thermal stability, mechanical profiling of the ESM samples were performed and demonstrated suitable profiles for translational applications. Biological in vitro studies using SV40 immortalised corneal epithelial cells (ihCEC) and corneal mesenchymal stromal cells (C-MSC) demonstrated excellent biocompatibility. Taken together, these results document the development of a novel sustainable biomaterial that may be used for ophthalmic wounds and/or other biomedical therapies.

Effect of calcination temperature on the microstructure, composition and properties of nanometer agglomerated 8YSZ powders for plasma spray-physical vapor deposition (PS-PVD) and coatings thereof

Homemade nano-agglomerated powders 8YSZ powders for PS-PVD were prepared by the spray drying, then calcination processes at four different temperatures (500 °C, 700 °C, 900 °C and 1100 °C) were carried out on the spray-dried powders. Checked by laser particle sizer, scanning electron microscope (SEM) and X-ray diffraction (XRD), the physical properties, microstructure and phase constitutions of the calcined powders were investigated. The results show that the size of powders calcined at 500 °C is increased relative to the spray-dried powder, whereas the powders calcined at 700 °C, 900 °C and 1100 °C possess smaller size. The binding force of the primary particles tend to rise with the increase of calcination temperature. When the temperature was up to 900 °C and above, it was found that the sintering neck indicating with strong binding was formed between the primary particles. In parallel, the powders underwent an m-ZrO2 to t-ZrO2 transition as the calcination temperature rose. It is also found that the PS-PVD prepared coatings which were obtained by using the above powders undergo a transformation from a feather-like to a dense laminate structure as the calcination temperature rises. It is noteworthy that the coating obtained by the powders calcined at 700 °C have a special three-layer composite structure of near dense surface layer, columnar intermediate layer and dense sub-layer. The composite structural coating has excellent adhesion and thermal shock resistance, with a bonding strength of 81MPa and no major spalling when water quenched 100 cycles at 1100 °C.

Ultra-light planar meta-absorber with wideband and full-polarization properties.

Absorbers have high potential application values in the military field, such as electronic screening, radar cross-section reduction and invisible cloaking. However, most methods have the defects of narrow bandwidth, low absorptivity, complex three-dimensional structure and fixed polarizations. In this paper, we realize an ultra-broadband and full-polarization planar metamaterial absorber (PMA) with a three-layer composite structure, which exhibits multi-resonant and impedance matching properties by combining the ultra-light foams and indium tin oxide (ITO) films. The bottom two layers achieve a high-efficiency absorption rate at the low and medium spectrum, while the upper layer realizes a absorption property at a high frequency. Also, an equivalent circuit model is extracted to explain its operating mechanism. The experimental results show that our meta-absorber can achieve great absorber performance of better than 90% within 1-18 GHz for full-polarization incident waves, which is in great agreement with the numerical simulations. Moreover, our device is insensitive to oblique incidences and polarizations and possesses the physical characteristics of an ultralight, weighing 0.6 kg for a square meter, which is only 1/85.0-1/126.7 of the conventional absorbers under the same size. All these excellent performances determine that our research can be a good candidate for military stealth materials.

Cardiac Troponin I Microfluidic Chip Driven by Adaptive Pressure

To develop and design an adaptive microfluidic chip for accurate determination of cardiac troponin I (cTnI) in whole blood sample and explore the operating parameters of the chip in detecting cTnI, in order to provide a novel strategy for the detection of cTnI, cTnI microfluidic chip was prepared by injection moulding, and the improved polystyrene polymer was used as the chip substrate to construct a three-layer composite structure, namely the upper, middle, and lower layers. The antihuman troponin I antibody I/II was grafted onto the chip surface to construct the detection reaction zone using UV-induced production of surface-active free radicals. The stability of the chip preparation process, the running performance of the chip, and the analytical performance of the whole blood samples were investigated. It was shown that I adaptive pressure-driven microfluidic chip has the advantages of easy bonding, integration, and a simple and stable production process. In the actual detection and analysis, the chip has high selectivity for cTnI in whole blood, lower detection limit (0.054 ng/mL), and small difference between batches (RSD% 2.50%). Therefore, the chip is assumed to provide novel strategy for the assessment of myocardial infarction by detecting cTnI.

Enhanced solar evaporation efficiency based on the inserted preheating zone of silver nanowires

In this paper, a new type of floating solar evaporator with a three-layer composite structure has been successfully fabricated, with the carbon nanotube (CNT) as the photothermal layer, the silver nanowires as the preheating layer and the glass fibers as the insulation layer. The solar evaporator exhibited excellent solar absorption and photothermal conversion properties, and the surface temperature of the dried evaporator could reach 106 °C under one solar irradiation intensity. Importantly, the pure water evaporation rate and the solar evaporation efficiency of this evaporator were 1.70 kg/m2 h and 95%, respectively. Based on the multi-layer composite structure of the evaporator, the addition of the silver nanowires as the preheating layer effectively reduced the loss of the thermal energy of the photothermal layer as the heat source and the evaporation region. The purpose of this study is to improve the solar energy efficiency by reducing heat conduction losses through the design of evaporators.

Mathematical simulation of the process of putting a connective insert into the orifice in a three-layered composite structure

This article provides the reader with the mathematical model determining the dependence of design parameters of embedding of a connective insert in a three-layered composite structure on its strained state at the outer diameter. Insert material is assumed to be a plastic body with nonlinear hardening. The model is adapted for implementing in the standard finite-element software ANSYS Mechanical used for numerical simulation of the process of embedding of the connective insert.

TECHNOLOGICAL ASPECTS OF CREATING A FIBER-OPTIC NON-DESTRUCTIVE TESTING OF SANDWICH COMPOSITE STRUCTURES

The results of research on the formation of the system of built-in non-destructive testing of linings of composite three-layer structures by an optical method using fiber-optic sensors based on fiber Bragg gratings are presented. The features of creating an input/output zone for fiber-optic sensors as applied to three-layer composite structures are studied. Recommendations for ensuring the integrity and optimal functioning of the fiber-optic monitoring system as applied to a real three-layer composite structure are formulated. The following is shown. The process of creating an integrated control system of three-layer composite structures by an optical method using integrated fiber-optic sensors includes a number of operations to form a topology and to ensure the output of fiber-optic sensors from composite claddings in a single technological cycle of manufacturing the structure according to the standard technological process without significantly adjusting it, which is extremely important in relation to serial technologies. When developing the technology of integrating fiber-optic sensors into a three-layer composite structure, it was experimentally shown that from the point of view of survivability and preservation of the efficiency of the embedded control system, it is necessary to fulfill a number of requirements for the placement and output of fiber-optic sensors taking into account the characteristics of manufacturing, machining, and operation designs. Thus, it is advisable to place fiber optic sensors in the casings at least 5 mm from the intended edge of the structure, at least 2 layers from the outer surface of the structure and not less than 5 layers from the honeycomb core. The fiber bend radius should be at least 30 mm to prevent mechanical burst and sharp bending of the signal when it is bending. Fiber optic sensors are recommended to be placed between layers with a reinforcement scheme in the direction of the fiber optic sensor, however placement is also allowed between the fiber sensors and one layer with a different direction of reinforcement, while in order to prevent fractures, computation fiber optic sensors overlap is unacceptable, thus, between crossover fiber-optic sensors must be at least 2 layers of prepreg.

High-Performance Triboelectric Nanogenerator with a Rationally Designed Friction Layer Structure

For a triboelectric nanogenerator (TENG), its output performance is largely determined by the quantity of triboelectric charge generated on the friction layer during the triboelectrification process. In this paper, we developed a new TENG by designing a three-layered composite structure (TLCS) for the positive friction layer. The TLCS was formed by stacking, from the outermost to the bottom, a charge collection sublayer (CCL), charge transport sublayer (CTL), and charge storage and barrier sublayer (CSBL). The CCL was used for robbing positive charges effectively from the negative friction layer. The CTL was used to transport the generated triboelectric charge deeper inside. The CSBL was used for holding more charges. By fabrication of TLCSs on both the positive and negative friction layers, the total triboelectric charge density increases from 0.97 to 16 nC/cm2, which greatly enhances the performance of the triboelectric nanogenerator.

Stability analysis of three-layer shear deformable partial composite columns

This paper is focused on the effect of imperfect bonding and partial composite interaction between the sub-elements of a box-type column on the critical buckling loads. The box column is modelled as a symmetric three-layer composite structure with interlayer slips at the interfaces, based on the Engesser–Timoshenko theory with uniform shear deformation assumptions. Linear shear springs or slip modulus is considered at the interfaces to model the partial interaction between the sub-elements of the structure. The minimum total potential energy principle is utilized to obtain governing equations and boundary conditions. A direct analytical solution of the original governing equations is presented for obtaining exact buckling characteristic equation of the three-layer partial composite column with different end conditions including clamped-pinned end conditions. Also, the coupled equations are recast into an efficient uncoupled form and shown that there is a strong similarity with those for the two layer element. It is shown that the obtained formulae are converted to the known Euler column formulae when the slip modulus approaches infinity (i.e. perfect bonding) and no shear deformations in the sub-elements are considered. A differential shear Engesser–Timoshenko partial composite model is also employed and critical buckling loads, obtained from an inverse solution method, are compared to examine the validity and accuracy level of the uniform shear model. Comprehensive dimensionless numerical results are presented and discussed.