Composition Of Layer Research Articles

A method introducing deteriorating bond at the interfaces and declining load transfer at the joints in the existing design methods for concrete pavements

Most of the concrete highways of the Belgian road system have a structure composed of a CRCP surface layer, a thin intermediate asphalt bond layer and a lean concrete base layer on one or more granular sub bases. They are designed as an equivalent composite rigid layer on an elastic granular sub grade. The equivalent Young’s modulus of the composite layer is assumed to be equal to the modulus of the concrete surface layer, the thickness is assumed to be equal to the sum of the thickness of the three layers; the equivalent moment of inertia and the equivalent stiffness depend on the values of the thickness and the moduli of each layer and the bond conditions between the layers. Several investigations regularly performed on pavements currently thirty years old have shown a systemic deterioration of the bond between the surface layers and of the load transfer at the cracks of the CRCP or at the joints of concrete slabs. In this paper we present a mathematical model that permits the computation of the influence of this systemic deterioration on the lifetime of the pavements.

Ultra Thin Continuously Reinforced Concrete Pavement Development in South Africa

Ultra thin continuously reinforced concrete pavements (UTCRCP), in literature also referred to as Ultra Thin Heavy Reinforced High Performance Concrete (UTHRHPC), have been used in Europe successfully as a rehabilitation measure on steel bridge decks and reported on at the 5th International CROW workshop in Istanbul (2004). This concept has been explored further in South Africa for use as a road strengthening measure by constructing experimental sections of 50 mm UTCRCP directly on top of both natural gravel and cement-treated natural materials. During the experiment the composition of the UTCRCP layer was varied in terms of mix design, steel fibre type and content, reinforcing steel mesh diameter and spacing. To date a total of 10 experimental sections have been tested using the Heavy Vehicle Simulator (HVS) and rendered structural lives that varied from 5 million to 90 million equivalent standard (80 kN) axles on medium to weak support structure. The results obtained were then evaluated through 3D-finite element modelling and the design was refined using laboratory tests. The refined UTCRCP design was then subjected to further HVS testing. The paper discusses the above process in more detail.

Multivariate Approaches Boosting Lithium-Mediated Ammonia Electrosynthesis in Different Electrolytes.

Ammonia electrosynthesis through the lithium-mediated approach has recently reached promising results towards high activity and selectivity in aprotic media, reaching high Faradaic efficiency (FE) values and NH3 production rates. To fasten the comprehension and optimization of the complex lithium-mediated nitrogen reduction system, for the first time a multivariate approach is proposed as a powerful tool to reduce the number of experiments in comparison with the classical one-factor-at-a-time approach. Doehlert design and surface response methodology are employed to optimize the electrolyte composition for a batch autoclaved cell. The method is validated with the common LiBF4 salt, and the correlations between the FE and the amount of lithium salt and ethanol as proton donor are elucidated, also discussing their impact on the solid electrolyte interphase (SEI) layer. Moreover, a new fluorinated salt is proposed (i.e., lithium difluoro(oxalate) borate (LiFOB)), taking inspiration from lithium batteries. This salt is chosen to tailor the SEI layer, with the aim of obtaining a bifunctional interfacial layer, both stable and permeable to N2, the latter being an essential characteristic for batch systems. The SEI layer composition is confirmed strategic and its tailoring with LiFOB boosts FE values.

SHELL MICROSTRUCTURE AND MINERALOGY OF THE MOLLUSC SPECIES <em>ANADARA UROPIGIMELANA</em> (BORY DE SAINT-VINCENT, 1827), <em>TIVELA STEFANINII</em> (NARDINI, 1933) AND <em>OLIVA BULBOSA</em> (RÖDING, 1798)

Mollusc shells are composite structures made of calcite and/or aragonite crystals and biopolymers, arranged in a great variety of microstructures. The formation of shell microstructures is affected by environmental and physiological factors and differences among microstructural types are believed to be of phylogenetic and adaptive biomechanical significance. Here, we characterise and illustrate for the first time, through SEM and XRD analyses, the shell microstructure and mineralogy of specimens of the bivalves Anadara uropigimelana (Bory de Saint-Vincent, 1827) and Tivela stefaninii (Nardini, 1933), and of the gastropod Oliva bulbosa (Röding, 1798), collected in the Upper Holocene HAS1 settlement and in a shell midden in the Khor Rori Archaeological Park (Oman). Anadara uropigimelana shows an aragonitic shell with an outer crossed lamellar layer, an inner complex crossed lamellar layer and an irregular simple prismatic pallial myostracum; periodic bands of dendritic nondenticular composite prisms occur in the outer part of the outer layer, reflecting seasonal changes in water temperatures and growth rates. Shells of Tivela stefaninii are aragonitic with an outer composite prismatic layer, a middle crossed lamellar layer and an inner complex crossed lamellar layer, whereas those of Oliva bulbosa are characterised by an irregular alternation of aragonitic crossed lamellar layers; a transitional layer defined by the occurrence of tidally controlled growth lines, a crossed lamellar callus and a myostracal layer are also described are also described in Oliva bulbosa. With this investigation, we provide novel microstructural and mineralogical data on these poorly known mollusc species, providing useful characters for phylogenetic, evolutionary, crystallographic, and palaeoenvironmental studies.

Numerical study on damage behavior of sandwich panels with fiber metal laminates skins subjected to blast and high-velocity fragments impact

The sandwich panel is extensively utilized in various protective structures due to its exceptional load-bearing capacity and blast resistance. In this study, a nonlinear finite element (FE) model is developed to examine the explosive impact behavior of sandwich panels featuring carbon fiber reinforced aluminum laminates (CRALL) skins and aluminum honeycomb core. Utilizing the 3D Hashin criterion and accounting for the strain rate effects on composite plies, the user subroutine, VUMAT, is employed to predict the damage response in composite layers. The Johnson–Cook model and bilinear traction–separation model are used to describe the dynamic responses of the metal layers and the inter-laminar delamination phenomena. The established FE model is validated against existing experimental data in ballistic impact conditions and subsequently employed to predict the explosive impact behavior of the sandwich panel. The dynamic response and damage mechanisms of the sandwich panel under blast impact, fragments impact, and combined impact loading are analyzed. Additionally, the effects of blast mass and impact angle on the explosive impact behavior of the sandwich panel are discussed in detail.

An electrochromic alginate fiber based on a W18O49/PEDOT:PSS composite layer.

In this experiment, we studied a technique that permits the continuous fabrication of electrochromic alginate fibers because there hasn't been much research on electrochromic alginate fibers. Therefore, it's important to investigate ways to increase the application areas of alginate fibers. AgNP‑calcium alginate fibers with high electrical conductivity were prepared by Ag+ substitution method. Electrochromic alginate fibers were successfully prepared by sequentially coating the fibers with PEDOT:PSS, W18O49, and PVDF:HFP to form a W18O49/PEDOT:PSS composite color-changing layer and a PVDF:HFP stable electrolyte layer. Fifty electrochromic alginate fibers with a length of 7cm were tested, and their resistance values ranged from 2 to 12Ω, of which 78% were between 3 and 8Ω, providing excellent electrical conductivity. In the electrolyte from 0.1V to -0.7V, the color of the fiber changes from the original state to the colored state in only 5s. Ten minutes after the voltage is disconnected, the color changes to the original color of the AgNP-Calcium Alginate fibers and the color change are reversible. The solid fibers can change from light blue to dark blue and the color change is uniform in the upright and bent state. This study lays a solid research foundation for the industrial production and intelligent application of electrochromic alginate fibers.

An electrochemical immunosensing of electrochemically modified carbon cloth electrode based on functionalized gold nanoparticle-Prussian blue for the detection of aflatoxin B1 in vegetable oil industry.

This study developed an electrochemical immunosensor for the detection of aflatoxin B1 (AFB1) in vegetable oil, based on an electrochemical modified carbon cloth (EMCC) electrode modified with a composite functional layer of cross-linked o-aminothiophenol functionalized AuNPs (o-ATP@AuNPs)/Prussian Blue (PB). The EMCC electrode substrate was prepared by modifying carbon cloth through electrochemical methods to increase its surface area, which allowed for the effective deposition of o-ATP@AuNPs/PB composite functional layer and improved the conductivity of the electrode material. The synergistic effect of o-ATP@AuNPs and PB significantly enhanced the sensitivity of the electrochemical sensor. Additionally, the AuS bond between L-Cysteine (L-Cys) and o-ATP@AuNPs improved the stability of the sensing interface. Under optimal conditions, the BSA/anti-AFB1/L-Cys/o-ATP@AuNPs/PB/EMCC sensor was able to detect AFB1 in the range of 0 to 20ngmL-1 using square wave voltammetry (SWV), with a detection limit of 0.015ngmL-1. The proposed sensor holds promise for future applications in the sensitive detection of AFB1 in vegetable oils.

MXene-based solvent-responsive actuators with a polymer-intercalated gradient structure.

Actuators based on electrically conductive and hydrophilic two-dimensional (2D) Ti3C2T X MXene are of interest for fast and specific responses in demanding environments, such as chemical production. Herein, Ti3C2T X -based solvent-responsive bilayer actuators were developed, featuring a gradient polymer-intercalation structure in the active layer. These actuators were assembled using negatively charged pristine Ti3C2T X nanosheets as the passive layer and positively charged polymer-tethered Ti3C2T X as the active layer. 2D wide-angle X-ray scattering and simulations related the gradient polymer intercalated microstructure in the polymer/MXene composite active layer to the counterintuitive actuation behavior. The bending of the bilayer films in solvent vapor is triggered by the gradient polymer-intercalation and the differing diffusion rate of solvent molecules through the MX and MX-polymer layers of the bilayer actuator. With their ease of fabrication, remote light-control capabilities, and excellent actuation performance, the Ti3C2T X -based bilayer actuators reported here may find applications in areas such as sensors for monitoring chemical production, infrared camouflage, smart switches, and excavators in toxic solvent environments.

Design, Fabrication, and Performance Optimization of a High-Temperature Thin Film Heat Flux Sensor with a Composite Protective Layer

Design, Fabrication, and Performance Optimization of a High-Temperature Thin Film Heat Flux Sensor with a Composite Protective Layer

Moisture diffusion in multi-layered materials: The role of layer stacking and composition

Moisture diffusion in multi-layered materials: The role of layer stacking and composition

Mechanical behaviour of 3D printed fiber-reinforced soft functional hydrogel composite: Opportunities for biomedical applications

Owing to the unique native properties of cellulose, such as biocompatibility, biodegradability, and excellent mechanical properties, it offers new strategies for designing environment-friendly, cost-effective, and high-mechanically robust hydrogel composites. Herein, we proposed the fabrication of 3D printed nature-inspired cellulose nanofibers (CNFs) reinforced anisotropic functional nanocomposite hydrogel structure.In this hypothetical study, we focuses on to develop nature-inspired 3D-printed Polyacrylamide PAM / Alginate (Alg) based single layered and multilayered laminate hydrogel composites reinforced with anisotropically oriented CNFs and performing finite element (FE) analysis study via implementing measured experimental material properties to explore the CNF reinforcement mechanism in the fiber-reinforced composite hydrogel. The FE modelling and simulation are based on an idealised anisotropic hyperelastic model used to analyse the anisotropic mechanical behaviour of the 3D printed hydrogel composite structure. The computational study of the nature-inspired printed helicoidally layup hydrogel composite construct exhibit enhanced mechanical properties, which offered appreciable stretchability, toughness and anisotropic mechanical behavior.It will assist the design of the more mechanically compliance composite hydrogel structure, making it suitable for load-bearing biomedical applications.

Bending properties of hardwood-based layered wood composites bonded with polyurethane adhesive modified by thermosets

Bending properties of hardwood-based layered wood composites bonded with polyurethane adhesive modified by thermosets

An experiment-modeling integrated approach to characterize friction between composites prepregs during preforming

During preforming of carbon fabric prepregs, multiple layers of composites will be deformed into parts with 3D geometry. Large relative sliding between different prepreg layers, especially when these layers have various initial stacking orientations, will significantly influence deformation of the prepregs and reorientation of the reinforcement yarns, greatly affecting performance of the final parts. However, it is challenging to correctly identify local environmental conditions, which can substantially change friction between prepregs, during preforming in closed molds. To tackle this issue, an innovative experiment-modeling integrated approach has been developed to iteratively characterize friction between prepregs under non-uniform conditions throughout the entire prepreg region and preforming process. This integrated characterization approach was supported by a self-developed tester to measure the coefficients of friction (CoFs) between prepregs under target preforming conditions, and a variable friction model with experimental data directly implemented using the bilinear Lagrange interpolation for finite element analysis (FEA) of preforming. Comparison between experimental and numerical modeling results regarding geometry and yarn angles of the single-dome benchmark samples from preforming indicates that the experiment-modeling integrated approach, supported by the reliable friction tester and the variable friction model, can effectively determine the complex friction conditions between prepregs during preforming, greatly improving accuracy of the process modeling at the end.

Composite layer evaluation based on multi-scale finite element analysis

Composite layer evaluation based on multi-scale finite element analysis

Clinically relevant cell culture model of inflammatory bowel diseases for identification of new therapeutic approaches.

Inflammatory Bowel Diseases (IDB) are chronic disorders characterized by gut inflammation, mucosal damage, increased epithelial permeability and altered mucus layer. No accurate in vitro model exists to simulate these characteristics. In this context, drug development for IBD or intestinal inflammation requires in vivo evaluations to verify treatments efficacy. A new model with altered mucus layer composition; altered epithelial permeability and pro-inflammatory crosstalk between immune and epithelial cells will be developed to enhance in vitro models for studying IBD treatments. The effects of dextran sulfate sodium and/or lipopolysaccharides on intestinal permeability, cytokines synthesis (IL-6, IL-8, TNF-α and IL-1β), mucins (MUC2, MUC5AC) and tight junction proteins expression (Claudin-1, ZO-1 and Occludin) were investigated in a tri-coculture model combining differentiated Caco-2/HT29-MTX cells and THP-1 cells. Two anti-inflammatory agents were evaluated to assess the model's therapeutic strategy applicability (corticoids and pro-resolving factors). Two in vitro models have been developed. The first model, characterized by increased permeability of the epithelial layer and subsequent secretion of inflammatory cytokines, can reproduce the different phases of inflammation, and enables the evaluation of preventive treatments. The second model simulates the acute phase of inflammation and allows for the assessment of curative treatments. Both models demonstrated reversibility when treated with betamethasone and pro-resolving factors. These in vitro models are valuable for selecting therapeutic agents prior to their application in in vivo models. They enable the assessment of agents' anti-inflammatory effects and their ability to permeate the inflamed epithelial layer and interact with immune cells.

Analyse the effect of carbon fiber reinforced polymer (CFRP) strengthening of beams using ANSYS

This paper presents a nonlinear finite element model analysis to effect of carbon fiber reinforced polymer (CFRP) strengthening of beams using ANSYS, Finite element software ANSYS 12.0 has been used for modeling the beams by conducting nonlinear static analysis. The SOLID 65 and SHELL 181, LINK180 elements have been used to, respectively; model the 3D concrete beams and the composite layer, steel rebars. The results of the finite element were compared with the experimental data The results showed that the general behavior of the finite element models represented by the load-deflection curves shows good agreement with the test data from the previous researches.

Experimental Analysis on Optimum Use of Filler Materials of River Bed Sub Base Sample for Pavement

Composition of different layers to resist the traffic load as per design on the flexible pavement, among them subbase is one. This research carried out to optimization of filler sample on riverbed sub-base material whose plastic index is nil. The sub-base material plays a pivotal role in supporting the overlying pavement structure, and optimizing its properties is essential for enhancing overall pavement performance The observations through laboratory testing and trials ensure the modified sub-base material meets the necessary performance criteria. The study aims to contribute valuable insights into sustainable and effective pavement construction practices and presents an experimental analysis focused on improving riverbed sub-base material through the optimal utilization of filler materials. During laboratory trials all necessary requirement, like gradation, plastic index, specific gravity, maximum dry density and California bearing ration are observed. From laboratory trials 10% threshold appears to be a critical point where the material satisfies the specified requirements, define by Government of Nepal, Department of Road, Standard Specification for Road and Bridges-2073 (with second abdmanent-2078). Regular quality control and testing during construction are essential to confirm that the material consistently meets the desired specifications. Additionally, collaboration with geotechnical engineers and adherence to local standards and guidelines are crucial in ensuring the longterm performance of road constructions.

Predicting the presence of tephra layers in lacustrine deposits using spectral gamma ray data: An example from Lake Chalco, Mexico City.

Spectral gamma ray borehole logging data can yield insights into the physical properties of lake sediments, serving as a valuable proxy for assessing climate and environmental changes. The presence of tephra layers resulting from volcanic ash deposition is not related to climate and environmental conditions. As a result, these layers pose challenges when attempting to analyze paleoclimate and environmental time series. Gamma rays are composed of photons, which are elementary particles of electromagnetic radiation. Tephra layers emit photons at specific energy levels that create a distinct pattern in their gamma-ray energy spectrum. The gamma-ray signature of tephra layers varies depending on the stage of the volcanic eruption. Additionally, there is a significant difference between the gamma-ray signature emitted by tephra layers and that of the background lake sediments. A composite signature can be used to predict tephra layers from background sediments by combining several gamma-ray signatures of tephra layers at different depths. We propose five-step protocol for detecting tephra layers within sediments through the utilization of gamma-ray spectroscopy. This protocol is based on a combination of physical aspects of gamma-ray spectroscopy and geological information specific to the lake system being studied. A subset of the training dataset is used, consisting of known tephra and non-tephra layers. The protocol involves identifying similarities between known tephra layers, analyzing differences in gamma-ray signals between tephra and non-tephra layers, and studying the composition of energy channels at various depths within the training dataset. Multiple linear regression models are used to predict the relationship between the composition of tephra layers as a dependent variable and the constituent energy channels of the gamma-ray signal as independent variables. The proposed protocol has the potential to accurately detect and identify thick tephra layers (> 10 cm in thickness) based on the rate of spectral gamma ray measurement in sedimentary sequences. This approach could enhance stratigraphic resolution by enabling finer subdivision of layers in an interior basin.

First Basic Problem of Elasticity Theory for a Composite Layer with Two Thick-Walled Tubes

The spatial problem of elasticity theory for a fibrous composite in the form of a layer with two thick-walled cylindrical tubes is solved. Stresses are given on the flat surfaces of the layer and on the inner surface of the tubes. The solution to the problem is presented in the form of Lamé equations in different coordinate systems, where the layer is considered in a Cartesian system and the tubes – in local cylindrical ones. To combine the basic solutions in different coordinate systems, the generalized Fourier method is used. Satisfying the boundary conditions and conjugation conditions between the layer and the tubes, an infinite system of integro-algebraic equations is formed, which is reduced to linear algebraic equations of the second kind, and the reduction method is applied. After finding the unknowns, it is possible to obtain the stress-strain state at any point of the elastic combined bodies using the generalized Fourier method to the basic solutions of the problem. According to the results of numerical studies, it can be stated that the problem can be solved with a given accuracy, which depends on the order of the system of equations and has a rapid convergence of solutions to the exact one. Numerical analysis of the stressed state was considered with a variation of the distance between the tubes. The graphs of the distribution of internal stresses in the tubes and the layer are obtained. The results show an inverse relationship between the magnitude of stresses and the distance between the tubes. In addition to the absolute value of stresses, changes in the character of the diagrams and the sign are possible. The proposed method of solution can be applied in the design of a layer with tubes. The obtained stress-strain state makes it possible to preliminarily evaluate the geometric parameters of the structure. Further development of the research topic is necessary for a model where tubes are combined with other types of inhomogeneities.

Tribological Behavior of Gas-Nitrided 42CrMo4 Steel at Elevated Temperatures

Nitriding is a well-known thermochemical treatment improving the surface hardness and the wear resistance of steel. The phase composition and growth kinetics of the nitrided layer can be controlled using a gas nitriding with changeable nitriding potential. In this work, such a gas nitriding was used to produce, on 42CrMo4 steel, the two nitrided layers differing in the thickness of compound zone and diffusion zone. The microstructure and nanohardness of these layers were studied. For the first time, the tribological behavior of gas nitrided layers at elevated temperatures (from 23 to 400 °C) was investigated. The compound zone consisted of ε + (ε + γ’) iron nitrides and, in the diffusion zone, the nitric sorbite with γ’ precipitates was observed. The highest nanohardness was measured in the ε + γ’ zone. The lowest values of friction coefficients were obtained if the contact surface of the friction pair entered the ε + γ’ zone. After the wear process, at a final temperature of 400 °C, worn surfaces showed only intensive abrasive wear, evidenced by shallow grooves. The increased oxygen content at the edges of wear tracks indicated possible oxidative wear.