Layers Of Sheets Research Articles

Microwave Plasma-Driven Synthesis of Graphene and N-Graphene at a Gram Scale

The large-scale microwave plasma synthesis of graphene and nitrogen-doped graphene with tailored structural properties, crucial for their successful usage applications, has been demonstrated. The developed atmospheric pressure plasma method offers several advantages, including the continuous production of high-quality, free-standing graphene without the use of chemicals, solvents, catalysts, or additional heating. This non-toxic process eliminates the need for vacuum systems while achieving high temperatures. The method enables the precise control over graphene’s properties, such as the layer number, defects, sheet size, uniformity, and functionality, as well as the doping type and configuration, by adjusting the plasma parameters. Protocols for the synthesis of specific nanostructures with a controlled structural quality, production rate, and chemical composition have been established using methane and methylamine as precursors. The comprehensive physicochemical characterization of the graphene and nitrogen-doped graphene was carried out using scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.

Preparation of a CNF porous membrane and in situ synthesis of silver nanoparticles (AgNPs).

We prepared a cellulose nanofiber (CNF)-based porous membrane with three dimensional cellular structures. CNF was concentrated via a surfactant-induced assembly by mixing CNF with a cationic surfactant, domiphen bromide (DB). Furthermore, they were accumulated by centrifugation to obtain a CNF-DB sol. Next, when the CNF-DB sol was naturally dried, a membrane composed of densely packed CNF was obtained. On the other hand, when the CNF-DB sol was freeze-dried, a porous membrane with the anisotropic cellular structure could be obtained. The interspace between layered CNF sheets was tunable by the DB concentration in the assembly process and the centrifugal force in the accumulation process. FT-IR analysis of the porous membrane showed the formation of hydrogen bonds between the CNF, resulting in facilitation of crosslinking of the CNF and formation of the cellular structures. The obtained CNF-DB membrane exhibited high water resistance. They showed a high ability to absorb hydrophobic dyes such as Nile red and rhodamine B (RhB) due to the presence of the hydrophobic core of DB micelles. Then, the release of RhB could be controlled by the ionic strength in the medium. In addition, they possessed a high ability to adsorb cationic metals such as Ag ions due to the presence of carboxyl moieties of CNF. Next, in situ synthesis of silver nanoparticles (AgNPs) was carried out by employing the CNF-DB membrane as a template for Ag ion adsorption and reduction. Deposition of AgNPs could be observed on the CNF-DB membrane, which suppressed aggregation of AgNPs. Almost all AgNPs were arrayed apart from each other to generate the hotspots, which could enhance surface-enhanced Raman scattering (SERS) of AgNPs. Such an AgNPs-CNF composite membrane could be applied for a label-free analysis of adsorbed RhB.

Capabilities of asymmetric rolling of single-layer and laminated materials made from aluminum and its alloys

Asymmetric rolling of aluminum alloys is one of the methods for improving their mechanical and performance characteristics. Kinematic asymmetry during rolling is achieved by varying the roll speed ratios (V1 /V2). It is believed that when V1 /V2 > 3, the process of asymmetric rolling, by combining significant compression and shear deformations, approximates the processes of severe plastic deformation. It has been found that the majority of studies are based on data obtained within a limited roll speed ratio range, V1 /V2 < 2, in asymmetric rolling. This article examines the effects observed at V1 /V2 = 1÷7.7. The implementation of this condition became possible thanks to a unique scientific facility – the 400 laboratory-industrial asymmetric rolling mill at the Zhilyaev laboratory “Mechanics of Gradient Nanomaterials” at Nosov Magnitogorsk State Technical University Experiments were conducted on asymmetric thin-sheet rolling of aluminum alloys 2024, 5083, and 6061, as well as accumulative roll bonding to produce laminated sheet aluminum composites 5083/2024, 5083/1070, and 6061/5083. The disadvantages of asymmetric rolling compared to symmetric rolling were identified: sample failure was observed at single relative reductions of 37 % for layered sheet aluminum composites (5083/2024) and 40 % for thin-sheet aluminum alloys (6061). The nuances of material preparation for processing were described, including the necessity of cleaning and degreasing the alloy surfaces before bonding into a composite. The rolling temperature regimes were selected, determining cold asymmetric thin-sheet rolling (room temperature processing) and warm asymmetric accumulative roll bonding (heating of the workpieces in the furnace before rolling at 320–350 °C). A reduction in rolling force (by a minimum of 1.3 times), the ability to vary hardness (including an increase by a minimum of 30 %), and technological plasticity with changes in the roll speed ratios within the range of 2 to 7.7 were demonstrated. Options were proposed for reducing the processing cycles of aluminum alloys without compromising the quality of the finished product by reducing the number of rolling passes and annealing steps in the standard process scheme.

Facile synthesis of ternary NiFe2O4-Co3O4@G nanocomposite for supercapacitor

Abstract This work presents a novel NiFe2O4-Co3O4@G nanocomposite electrode for supercapacitors. NiFe2O4 nanoparticles along with Co3O4 were observed to be attached with graphene layer sheets. The prepared electrode with conductive network and porous structure offered a large active site to the electrolyte ions. NiFe2O4-Co3O4@G nanocomposite has shown a specific capacitance of 407 Fg–1 at a scan rate of 20 mVs−1 in 2 M KOH aqueous electrolyte. Moreover, NiFe2O4-Co3O4@G nanocomposite electrode exhibited a retention of 91% capacitance after 2000 cycles. The improved electrochemical performance of the composite is due to the synergistic effects among all three constituents and unique surface morphology with large effective surface area to the electrolyte ions.

Experimental Investigation on the Effectiveness of EB-CFRP Confinement of Elliptical Concrete Columns

This paper presents the results of an experimental study involving 20 tests performed on elliptical concrete columns confined with externally bonded carbon fiber-reinforced polymer (EB-CFRP) laminates. The study aimed to evaluate the effects of elliptical aspect ratio (A/B) as well as confinement rigidity (number of EB-FRP layers) on confinement effectiveness. The experimental program consisted of one series of control concrete columns (unstrengthened) and three additional series, each one strengthened with one, two and three layers of EB-CFRP sheets, respectively. Furthermore, each series considered five elliptical aspect ratios (A/B) ranging from 1.0 to 1.6. Following compressive concentric tests until failure, the results were analyzed to characterize the confinement level with an increasing number of EB-CFRP layers as a function of the elliptical aspect ratio. The results show considerable enhancements in compressive strength and in the ductility of the confined columns. Furthermore, this improvement is amplified as the number of EB-CFRP layers increases, indicating a proportional relationship between the compressive strength and the number of CFRP layers. It is found that the ultimate strength of EB-CFRP-confined columns with three layers reached up to 130% compared to the control specimens. However, increasing the elliptical aspect ratio reduced the compressive strength and ductility of confined columns. This study investigated the relation between the CFRP hoop and axial strains and the elliptical aspect ratios. Moreover, through comparison, the results reveal that the prediction models proposed by the Canadian standards S806-12 and S6-19 do not capture the negative effect of the elliptical aspect ratio in confined concrete columns.

Development of anti-bacterial bio-transfer double sheet layer of polyvinyl alcohol/carboxymethyl cellulose films infused with Astragalus tribuloides leaf extract for beef burgers preservation

This study was conducted to develop biodegradable films using a combination of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and purified leaves extract of Astragalus tribuloides (ATE). Various traits of the films, including their morphology description, thermal behavior, tensile/elongation properties and physical characteristics were examined. The scanning electron microscope (SEM) photographs showed smooth surface with small amounts of ATE, but rougher with higher concentrations of 1.4 %. The Fourier-transform infrared spectroscopy (FTIR) showed a direct relationship between the ATE extract and the PVA/CMC matrix. The films also showed thermal stability behaviors. The study found that the addition of ATE up to 0.8 % caused the films to become opaquer in color and raised their opacity up to 3.909. As a result, the films exhibited reduced moisture absorption (8.21 %) and solubility (27.11 %), making them retard penetrating water vapor up to (1.785 × 10−10 g.m−1 s-1 Pa−1) and could preserve the thiobarbituric acid reactive substances (TBARS) and overall color discrepancies of burger in refrigerated storage.

Numerical Response of Concrete-Filled Steel Tubular (CFST) Columns Externally Strengthened with FRP Composites Subjected to Cyclic Loading

The ultimate load-carrying capacity of concrete-filled steel tubular (CFST) columns exposed to monotonic loadings can be greatly increased by strengthening those columns, and the occurrence of the steel tube's outward buckling can be postponed. The current research aims to study the possibility of improving the structural characteristics of CFST columns exposed to cyclic loadings in terms of lateral load capacity and absorbed energy by strengthening them with different patterns of fiber-reinforced polymer (FRP) sheets. The ABAQUS software was used to create a three-dimensional (3D) non-linear finite element model (FEM) to simulate the behavior of FRP-strengthened CFST columns exposed to monotonic and cyclic loadings. After ascertaining the accuracy of the proposed model's results in successfully predicting failure patterns and lateral loads compared to the experimental results of tested specimens available in the literature, the model was used to create a parametric study. The parametric study focused on the impacts of the thickness, location, and length of the strengthening sheets on the failure pattern, lateral load-carrying capacity, stiffness, cumulative energy, absorbed energy, and viscous damping factor of the CFST columns exposed to cyclic loadings. The results revealed that the un-strengthened specimen displayed a maximum lateral load of 185 kN and a viscous damping factor of 45.2% at a lateral drift of 5.7%. On the other hand, strengthening the CFST column using five layers of FRP sheets exhibited the highest lateral load of all investigated columns (50% more than the un-strengthened specimen). Additionally, at a lateral drift of 5.7%, the decrease in viscous damping factor of CFST specimens due to strengthening using 1, 2, 3, 4, and 5 layers of FRP sheets with respect to the control specimen was 7.9%, 14.9%, 20.8%, 27.7%, and 30.3%, respectively.

INVESTIGATION ON THE STRENGTH OF E-GLASS FIBER/AA5052-H32 FIBER METAL LAMINATES CONNECTED USING RIVETED JOINTS

Fiber metal laminates (FMLs) belong to a class of composite materials comprising layers of metal sheets and fiber-reinforced polymers (FRP), configured in a specific sequence. This study investigates the tensile strength of FML specimens joined by riveted joints. FML plates were fabricated using AA5052 aluminium alloy, E-glass fibers, epoxy resin, and layered double hydroxide (LDH) via a hand layup process. The experimental parameters included the pattern of rivets, type of rivet materials, and rivet size. Tensile strength, the output response, was evaluated using Taguchi’s L9 orthogonal array design, followed by testing on a universal testing machine. The main effect plot and 3D surface plots were employed to analyze the tensile test results. Maximum tensile strength was held by the test specimen which was connected by the rivets made up of mild steel. From the ANOVA results presented in Table 6 , it was inferred that the number of rivets used for joining the FML specimens (pattern) played a major role in deciding the tensile strength of the specimens (57.25%). A regression equation, derived from Design Expert software, established the relationship between input variables and the tensile strength of FML specimens. ANOVA was conducted to assess the impact of each process variable on achieving optimal tensile strength. This research contributes novelty by integrating LDH into FML fabrication and demonstrates practical significance through systematic optimization of riveting parameters to enhance tensile strength. Quantitative and qualitative analyses underscore the effectiveness of the proposed FML configuration, validating its potential for structural applications.

Two-Dimensional Siloxene: A Promising Silicon-Based Material with Buffered Volume Change As Anode for Lithium Ion Batteries

Silicon has emerged as a potential anode material for lithium-ion batteries due to its high theoretical capacity of 3579 mAh g−1 (Li3.75Si). However, the alloy reaction with a high lithium content presents challenges, such as significant volumetric expansion and an unstable solid electrolyte interphase layer, which are detrimental to the electrodes and lead to rapid capacity fade [1]. Siloxene, a silicon compound with a layered structure, has attracted attention in lithium-ion battery applications due to its small volume change and moderate capacity [2, 3]. This material is obtained through the topotactic deintercalation of Ca2+ from layered CaSi2 [4]. Microscopically, the layered structure of siloxene consists of Si6 rings interconnected with or without oxygen to form planes, with Si–OH/Si–H bonds on the surface of these planes [5]. Macroscopically, siloxene exhibits a morphology of stacked layered sheets. Our research explored how the layered morphology of siloxene changes during the lithiation/delithiation process. Figure 1 showed that the siloxene sheets bulge together during lithiation and revert to separate sheets after delithiation. The buffered volume change of the layered siloxene material contributed to significantly better cycling performance compared to chunky SiO and spherical Si/C materials. Additionally, the cycling performance of siloxene was further improved when it was blended with graphite materials.[1] Kim, N., Kim, Y., Sung, J., & Cho, J. (2023). Issues impeding the commercialization of laboratory innovations for energy-dense Si-containing lithium-ion batteries. Nature Energy, 8(9), 921-933.[2] Loaiza, L. C., Monconduit, L., & Seznec, V. (2020). Si and Ge‐based anode materials for Li‐, Na‐, and K‐ion batteries: a perspective from structure to electrochemical mechanism. Small, 16(5), 1905260.[3] Loaiza, L. C., Dupré, N., Davoisne, C., Madec, L., Monconduit, L., & Seznec, V. (2021). Complex lithiation mechanism of siloxene and germanane: two promising battery electrode materials. Journal of The Electrochemical Society, 168(1), 010510.[4] Yamanaka, S., Matsuura, H., & Ishikawa, M. (1996). New deintercalation reaction of calcium from calcium disilicide. Synthesis of layered polysilane. Materials Research Bulletin, 31(3), 307-316.[5] Weiss, A., Beil, G. & Meyer, H. (1980). The Topochemical Reaction of CaSi2 to a Two-Dimensional Subsiliceous Acid Si6H3(OH)3 (= Kautskys’ Siloxene). Zeitschrift für Naturforschung B, 35(1), 25-30. Figure 1

Carbon fiber reinforced polymer (CFRP) laminates: flexural strengthening method for prestressed concrete beams with anchorage loss

Abstract Post-tensioning (PT), a method of pre-stressing, involves the use of high-strength steel strands/ tendons to reinforce concrete or other materials. On the contrary, Carbon Fiber-Reinforced Polymers (CFRP) are lightweight, high-strength materials with used to strengthen concrete structures by adhering the polymer to the concrete element. Challenges with post-tensioned elements include reverse curvature of the post-tensioning strands, tendon misplacement, and frequent damage in the anchorage and dead-end zones. These difficulties frequently cause bulging of the surrounding concrete, even at lower stress levels, and can lead to concrete bursting when tension exceeds certain threshold. This study investigates into the potential of CFRP strengthening technique to improve the flexural capacity of post-tensioned concrete beams with anchorage loss. Through an experimental program, the study compares the performance of control beams to those reinforced with different layers of CFRP. The results of this study demonstrated that there was a significant increase in flexural capacity, ranging from 45.31% to 78.62% for single layers and 87.17% to 153% for double layers of CFRP sheet. Additionally, the research examines how different levels of prestressing and CFRP wraps influence crack formation and delamination patterns of carbon fiber, with promising results. It was also noted that optimal usage of CFRP fibers and tendons is found to be critical. The study suggests exploring alternative fiber types and orientations for future study.

FDTD algorithm for subcell model with cells containing layers of graphene thin sheets

FDTD algorithm for subcell model with cells containing layers of graphene thin sheets

Insights of physicochemical structure changes of bituminous coal with acidification-assisted controlled electric pulse through SEM, XRD and FTIR

Controlled electric pulse (CEP) cracking coal effectively enhances its permeability, but a high coal breakdown voltage (BV) can result in technical difficulties. To address this problem, the method of using HCl solution to improve the electrical conductivity of coal was proposed. The effects of HCl on coal BV were investigated, and the microstructural changes in coal were analyzed through scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Compared with raw coal, the BV of acidified coal decreased significantly. The crushing degree of the coal samples was clearly enhanced with an increasing HCl concentration. Some internal coal minerals were acidified and dissolved, the aromatic layer spacing (d002) increased and the layer sheet stacking height (Lc) decreased, and the crystal structure was damaged. When acidified coal was broken down, numerous internal pores and cracks appeared, active coal groups were shed, the aliphatic hydrocarbons and oxygen-containing functional group contents increased, surface activity was reduced, and the hydroxyl content was reduced, which was conducive to rapid gas desorption. Acidification effectively reduces the BV of coal and improves the cracking and permeability enhancement effect of coal by CEP action.

Research on fatigue life of carbon fiber reinforced polymer strengthened single-sided butt welded joints utilizing resin pre-coating for strong adhesive bonding

Single-sided butt welding is a common connection method used in box beam structures such as excavator booms. Single-sided butt weld joints are prone to fatigue failure since the structures are subjected to cyclic loads over extended periods. The purpose of this study is to improve the fatigue performance of single-sided butt welded joints. Carbon fiber reinforced polymer (CFRP) strengthened single-sided butt welded joint specimens with permanent backing plates were prepared by pre-coating method, and constant-amplitude tension–tension fatigue tests were carried out on the specimens. The effects of welding groove parameters and CFRP reinforcement on fatigue life were studied. The test results show that the CFRP-strengthened specimens without blunt edges and with a groove angle of 40° show the highest average fatigue life. The single-sided bonding of 10 layers of CFRP sheets effectively inhibits the propagation of fatigue cracks and significantly improves the fatigue life of welded joints. In the CFRP/welded joint composite structure, the strain monitoring results show that the peak strain of the interface is the largest in the middle position, and the peak strain rises sharply in the rapid crack propagation stage, which indicates that the real-time interface strain peak can reflect the fatigue crack propagation. It provides an early warning method for real-time monitoring of fatigue life failure of welded structures in practical engineering.

Device to circuit level implementation of JL-NSFET for DC/analog/RF applications at sub-5nm technology node: design optimization and temperature analysis

Abstract This manuscript introduces, for the first time, a novel approach that incorporates a comprehensive analysis of sheet variations (1–5) and every individual sheet wise temperature variation, and as well as an investigation of various GS high-k gate dielectrics in Junction-less (JL) Nanosheet FET (JL-NSFET). The study starting from device level (Digital/Analog/Radio Frequency) to circuit (CMOS Inverter and ring oscillator) as a whole package is investigated through well calibrated TCAD simulation and the results portrayed. NSFETs are the ultimate choice for integrated circuits (ICs) at sub-5 nm technology node. The notion of this paper is to design and optimization of NSFET with GS high-k gate dielectrics (Al2O3, HfO2, ZrO2 and TiO2) Initially. The switching/analog and RF metric revels that HfO2 is superior in terms SS, switching applications and more compactable with CMOS process. Further, adding number of sheets and temperature variation has been done later. As number of sheets increases, the effective channel width increases, electric field distribution takes place evenly and enhanced gate control owing to improved I O N , I O N / I O F F r a t i o , SS and DIBL. However, increasing the number of vertical channel layers (sheets) more than 2 results into diminished analog/RF performance of JL-NSFET owing to increased parasitic capacitances. Further, the impact of temperature variations (250 K to 450 K) studied for different sheet variations (1 to 5) and noticed that analog/RF such as gm, gds, fT, TFP and GTFP are enhanced by 40.82%, 28.76%, 40.69%, 64.62% and 70.59%, respectively at lower temperature (250 K) when compared to high temperature (450 K). These enhancements make the device is ideal for applications in cryogenic computing systems, satellites, deep space probes, and other aerospace technologies. Furthermore, as the circuit level implementation CMOS inverter and 5-stage ring oscillator (RO) are examined for different sheets and observed as sheets increase delay and EDP increases. For a CMOS inverter the NMH (0.295 V) and NML (0.280 V) are better at 2 sheets with a highest gain of 9.38 V/V. Hence, it is advised to use two or three sheets-based JL-NSFETs for high-performance and lower-power analog/RF applications.

PbO2/rGO Electrode as a Superior and Efficient Anode in Electrocatalytic Degradation of Safranine-O

The electrocatalytic degradation method with PbO2/rGO electrode (anode) was chosen to treat Safranine-O waste because it was cheap and environmentally friendly. This research aimed to study the electrocatalytic efficiency of PbO2/rGO working electrode in Safranine-O removal. In this research, rGO and PbO2/rGO electrodes were synthesized and applied to Safranine-O removal through electrochemical degradation. The characterization results of the morphology of rGO are in the form of a layered structure and have the atomic composition of C (82.87%) and O (17.13%). The characterization results of PbO2/rGO are uniform particles with gaps/pores that appear relatively large. The rGO particles in the form of sheets (layers) seem to be distributed on the surface of PbO2. PbO2/rGO electrode has the atomic composition of C (87.24%), O (9.03), and Pb (3.73). The application of PbO2/rGO anode to the electrochemical degradation of Safranine-O showed good performance. It was able to perform dye removal (DE%), as well as a decrease in BOD and COD values up to >95% within 10 minutes at a concentration of 20 ppm. Application on real waste also showed the ability of dye removal, COD, and BOD reduction up to >95%. Coating or modifying the PbO2 anode with rGO can reduce the dissolution of Pb2+ ions in the solution during the electrochemical degradation. This study concluded that the PbO2/rGO electrode has improved the efficiency in Safranine-O degradation. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A-351 Versatile and Sensitive Microfluidic Immunoassay for Improved Point-of-Care Diagnostics

Abstract Background Healthcare professionals must choose between sensitivity and ease-of-use in diagnostics, particularly for diseases like COVID-19 and strep throat. Traditional enzyme-linked immunosorbent assays (ELISAs) are sensitive but are manually intensive and lengthy. Lateral flow assays (LFAs) are an alternative with low cost, ease-of-use, and rapid results; but LFAs suffer from low sensitivity. Burst Diagnostics presents a groundbreaking solution with the capillary-driven immunoassay (CaDI), a novel microfluidic device delivering sensitivity comparable to ELISA with the ease of LFAs. Methods The CaDI is made of flow channels defined by layered transparency and adhesive sheets containing reagent pads with HRP-conjugated antibody and luminol. The system requires only a sample addition step by the user. Sample flow initiates sequential steps of a sandwich ELISA, fully automated by the device, to provide a chemiluminescent signal in 10 minutes or less, depending on sample matrix. Results We have demonstrated success with preliminary studies for the detection of SARS-CoV-2 nucleocapsid protein (NP) and group A streptococcus (GAS). Detection of NP was achieved by assembling and optimizing COVID-19 CaDI’s using anti-NP antibodies. Then, spiked nasal swab samples were tested ranging from 10 to 1000 PFU/mL with positive detection as low as 10 PFU/mL, much less than the same samples in a traditional LFA (see figure). Additionally, we have demonstrated successful detection of GAS in optimized buffer conditions up to 100-fold less than commonly used LFAs. Finally, multiplexed CaDI’s increase throughput and cost-effectiveness in the point-of-care setting. Conclusions The CaDI platform bridges the ease of LFAs and sensitivity/specificity of laboratory tests. Currently, the CaDI can detect SARS-CoV-2 NP and GAS with higher sensitivity than existing LFAs. Development is underway for a reader to accompany the CaDI and further simplify the test. Importantly, the potential targets for detection are immense due to the sensitivity, simplicity, and adaptability of the platform.

Ultra-low-thickness, highly sensitive, and perfect-absorption THz refractive index and temperature sensors based on Tamm plasmon polaritons and Fabry-Perot resonators

In this paper, an ultra-low thickness with high sensitivity and perfect absorption based on the excitation of Tamm plasmon polaritons and Fabry-Perot resonance for sensing applications is presented. The sensor comprises a graphene sheet, a spacer layer, an analyte region, and a one-dimensional periodic stack of the dielectric and metal layers. The sensor’s performance is evaluated using the transfer matrix method under different conditions, including the presence of the graphene sheet and metallic layers of the periodic stack, a change in the chemical potential of the graphene sheet, the thickness of the layers, as well as the incident polarization and angle. The simulation results show that the presence of the graphene sheet causes stimulation of Tamm plasmon polaritons, and the presence of metal layers simultaneously increases the absorption and decreases the thickness of the sensor. The sensitivity of the sensor is 0.9667 THz/RIU (equivalent to 305 μm/RIU) with an absorption peak of 99.99 %. The use of silicon as the analyte allows the proposed structure to perform as a temperature sensor in the range of 1 THz, which results in a temperature sensitivity of 0.055 THz/°C (equivalent to 16.45 nm/°C). The proposed sensor has the advantages of extremely thin thickness, perfect absorption, high sensitivity, tunability, and fabrication-friendly structure. The proposed sensor has high potential for use in various sensing applications.

Characterizing nonlinear constitutive behaviors of fiber metal laminates

Abstract This study characterized the nonlinear tensile behavior of fiber metal laminates (FMLs). FMLs comprise layers of thin metallic sheets and fiber-reinforced composite layers, and a constitutive FML model includes the constitutive relationships of the FML’s constituent materials; however, nonlinear behavior is typically only considered for the metal components of an FML. In this study, a nonlinear constitutive relationship for the unidirectional fiber composites was modeled using a one-parameter plastic model. The nonlinear constitutive law for the metal was formulated using the J2 flow rule. These relationships were summed for each layer in accordance with laminated plate theory to obtain a constitutive FML model, which was then used for numerical predictions of nonlinear stress–strain curves. The model was validated by comparing its predictions with experimental results from the literature. Moreover, the effect of the inclusion of nonlinear fiber composite behavior on the model predictions was investigated. Results revealed that the difference between the model predictions and the experimental results was less than 4%. These predictions with nonlinear fiber composite behavior were substantially more accurate than those of the model without this behavior for FMLs with angle-ply fiber composites.

Remodeling of Uterine Tissues During Gestation of Potamotrygon wallacei (Elasmobranchii), a Neotropical Freshwater Stingray Endemic to the Negro River, Central Amazonia.

Neotropical freshwater stingrays of the subfamily Potamotrygoninae exhibit aplacental viviparity with uterine trophonemata. In this reproductive mode, females nourish and provide oxygenation to the embryo via the mucosa of the uterine wall. The aim of this study was to describe and histologically quantify the tissue components of the gravid uterus in an Amazonian freshwater stingray. Adult females of Potamotrygon wallacei were studied in different reproductive periods: resting stage, pregnant, and postpartum. During reproductive rest, the left ovary has numerous follicles compared to the right side. Therefore, uterine fertility is usually higher on the left side. The presence of an embryo in the right uterus suggests that the right ovary is also functional, although this only occurs in larger females. In females at reproductive rest, the wall of the uterus is formed by a mucosal layer (without the trophonemata) that contributes 16.7% to the thickness, while the myometrium accounts for 83.3% of the thickness. The mass-specific volume of the mucosal layer, inner circular, and outer longitudinal smooth muscle sheets tend to increase in the gravid uterus, indicating hypertrophy and hyperplasia of these components. During pregnancy, the trophonemata undergo marked tissue remodeling. Epithelial cells are organized into glandular acini and have apical secretory vesicles; furthermore, peripheral blood vessels proliferate and become dilated. These characteristics demonstrate that the gravid uterus of P. wallacei presents intense uterolactation activity and provides oxygenation to the fetus. Tissue remodeling occurs only in the uterus with the presence of an embryo. During postpartum, females have low body condition factor indicating a high reproductive cost. This study contributes to the knowledge of the reproductive biology of this species and will help us understand the impacts of climate change on the breeding areas of potamotrygonids.

Water wicking in phosphorene-based nanochannels: Effect of surface texture

The imbibition dynamics of water in a nanochannel made of two-dimensional phosphorene are explored using Molecular Dynamics. The partial wetting behavior of water nanodroplets on phosphorene sheets is examined first. The initial spreading of the wetted area (A) and internal energy (ΔE) are found to follow the power law, A ∼ t1/2 and ΔE-t1/2. Additionally, the Laplace pressure and equilibrium contact angle, determined from water plugs confined within nanoslits, verify the applicability of the Young-Laplace equation at the nanoscale. For water wicking in channels with a width of N layers of phosphorene sheets, the rate of change of both the penetration length and internal energy is proportional to t1/2. However, the imbibition rate in narrow nanoslits (N = 2 ∼ 5) depends on the orientation (armchair and zigzag) of the walls. This effect gradually diminishes as N increases. It was observed that, except for N = 1, the imbibition rate decreases with increasing channel width, which contradicts the prediction of Lucas-Washburn equation. Compared to smooth graphene-based channels, the imbibition rate is lower in phosphorene-based channels. Nonetheless, this difference decreases as the channel width increases, suggesting that the impact of surface roughness becomes less pronounced with larger channel widths.