Fabrication Of Architectures Research Articles

Highly efficient Polyaniline-MoS2 hybrid nanostructures based biosensor for cancer biomarker detection

In this work, polyaniline nanospindles have been synthesized using iron oxide as sacrificial template. These nanospindles were utilized for the fabrication of PANI-MoS2 nanoflower architectures via hydrothermal route. The electrostatic interaction between PANI and MoS2 improves the conductivity and provides more direct paths for charge transportation. SEM, TEM, XRD, Raman Spectroscopy techniques were employed to explore the crystal structure, and morphological properties of the PANI-MoS2 nanocomposite. Furthermore, an electrochemical biosensing platform based on PANI-MoS2 nanocomposite was fabricated for the specific detection of chronic myelogenous leukemia (CML) by using electrochemical impedance spectroscopy technique. The binding interactions between the pDNA/PANI-MoS2/ITO bioelectrode and target DNA sequence were also studied. The biosensor exhibits high sensitivity and wide detection range (10−6 M to 10−17 M) of target DNA with low detection limit (3 × 10−18 M). Additionally, the specificity studies of the genosensor with various target DNA sequences (complementary, noncomplementary and one base mismatch) and real samples analysis of CML shows its potential for clinical diagnostics.

Analysis of moisture diffusion induced stress in carbon/epoxy 3D textile composite materials with voids by µ-CT based Finite Element Models

The present paper focuses on the analysis of moisture diffusion, induced swelling and stress in carbon/epoxy 3D textile composite materials with voids using µ-Computed Tomography (µ-CT) image-based Finite Element (FE) Models. Based on real images of the material, the FE model includes all the details of the textile architecture, texture defects and voids. The moisture diffusion coefficient of the resin is identified from an optimization procedure which fits the results of the FE analysis to the experimental data from water absorption tests. The model is then used for diffusion simulation in a material without voids and for calculation of diffusion induced swelling and stress. The effective diffusion properties of the composite material are calculated using FE analysis with periodic boundary conditions (PBC) and used for analytical-based simulation of the diffusion behaviour. It is shown that the µCT image-based model does not predict Fickian behaviour, due to a microstructural effect. The µCT image-based model can be employed for the simulation of the moisture induced stress in the different phases of the composite material. The equivalent homogeneous model in which diffusion properties are “smeared” in an equivalent homogeneous orthotropic material cannot emphasize the distinct effect of the different phases.

A textile architecture-based hyperelastic model for rubbers reinforced by knitted fabrics

A new anisotropic hyperelastic model has been developed to model the deformation response of a knitted-fabric-reinforced rubber composite. The composite has a sandwich structure with a fiber net layer embedded in two rubber layers. Due to the architecture of the knitted fabric, the composite demonstrates an anisotropic hyperelastic response, which is modeled through a strain energy density function that incorporates the effects of deformed rubbers and stretched fibers. The rubber is considered as a neo-Hookean material, while the knitted fabrics are modeled as cords with negligible stiffness in bending. The effect of reinforcement comes from the conservation of the total length of the fiber cords. In addition, a slack variable is proposed to account for the effect of processing-induced fabric pre-stretch or fabric slack on the resulting composite response. This novel approach enables the determination of the constitutive behavior of the composite in closed form based on the constituent rubber and fiber properties and fabric architectures. The proposed analytical model is validated through a full 3D finite element (FE) model, in which the rubber and fiber reinforcement are modeled explicitly. Since the proposed model captures the key parameters that dictate the deformation response of knitted-fabric-reinforced composites, it can be employed as an efficient modeling tool to guide the design of rubbers and fabric architectures with targeted composite performance.

Compressibility of weft knitted reinforcement fabrics from glass yarn

Compression, and relaxation of a reinforcement fabric during composite manufacturing dictates mold design, resin flow, and fiber volume fraction of resultant composite; and single layer fabric architecture, and numbers of layers in a fabric stack change the compressibility character of overall reinforcement material. This study dealt with the effect of knit architecture and number of layers on dry compression and relaxation responses of weft knitted fabrics from glass yarn. Fabric architectures of 1x1, 2x2, English, and Fisherman ribs were selected. The thicknesses of single-, double-, and triple-fabric layers from same knit architectures were measured under compression and recovery pressures ranging from 2 to 200 kPa. Areal densities of single layer fabrics were measured. 2x2 and fisherman rib fabric architectures exhibited higher thickness, areal density and fiber volume fraction than 1x1 and English rib fabric architectures due to their nested and compact structures. Due to nesting between adjacent layers; multi-layer fabrics demonstrated higher fiber content than single layer fabrics. The difference between the compression and recovery thicknesses proved the existence of dissipated energy. Compression curves - the relationship between fiber volume fraction and compression pressure - classified by number of layers were fitted by square equation with fairly high determination of coefficients (R2).

Influence of solvents on Aloe vera gel performance in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) can be prepared from non-toxic, low-cost materials outside a cleanroom, opposite to common silicon-based cells. Especially for large areas, such as textile architecture, they can be used due to the aforementioned advantages. On the other hand, their efficiencies are very low if no specialized dyes – which are typically toxic and expensive – are used. This is why a broad variety of natural dyes has been investigated during the past decades.Here we report on aloe vera gel extracts, prepared with different solvents, as sensitizers for DSSCs. We show the dependence of the UV/Vis spectra on the solvents as well as the time-dependent electrical properties of the resulting DSSCs. Our results underline the influence of the solvent on the dye extraction and the corresponding DSSC efficiencies.

Thermal assisted self-organization of calcium carbonate

Fabrication of mineral multi-textured architectures by self-organization is a formidable challenge for engineering. Current approaches follow a biomimetic route for hybrid materials based on the coupling of carbonate and organic compounds. We explore here the chemical coupling of silica and carbonate, leading to fabrication of inorganic–inorganic biomimetic structures known as silica-carbonate biomorphs. So far, biomorphic structures were restricted to orthorhombic barium, strontium, and calcium carbonate. We demonstrate that, monohydrocalcite a hydrous form of calcium carbonate with trigonal structure can also form biomorphic structures, thus showing biomorphic growth is not dictated by the carbonate crystal structure. We show that it is possible to control the growth regime, and therefore the texture and overall shape, by tuning the growth temperature, thereby shifting the textural pattern within the production of a given architecture. This finding opens a promising route to the fabrication of complex multi-textured self-organized material made of silica and chalk.

Biocomposites based on plant material

Fibre reinforced composite materials offer superior specific mechanical properties in reference to their weight. In the past years, composite materials such as carbon or glass reinforced plastics (CFRP or GFRP) are used increasingly in all sectors of transportation and for industrial or leisure products. The composite consists of a load bearing fibre architecture, usually in the form of a continuous fabric architecture, and an embedding matrix, usually a thermoset such as epoxy. With regard to the energy efficiency and carbon footprint, due to their lightweight nature, these composite materials in general offer interesting properties, if applied in long-term operations. However, the raw materials used for the production of both typical fibre materials and thermoset resins are still based on crude oil, and the refining and processing up to the semi-finished good consume a significant amount of embodied energy. In this study, composites made of glass or flax fibres and resin systems based on condensed tannin and furfuryl alcohol, both extracted or derived from plant tissues, were manufactured using vacuum infusion (VI) and resin transfer moulding (RTM) processes. The results show that mechanical properties close to common fiber/resin combinations like glass fiber and epoxy or phenolic resins can be reached by these materials.

Effect of Unit Cell Type and Pore Size on Porosity and Mechanical Behavior of Additively Manufactured Ti6Al4V Scaffolds.

Porous metal structures have emerged as a promising solution in repairing and replacing damaged bone in biomedical applications. With the advent of additive manufacturing technology, fabrication of porous scaffold architecture of different unit cell types with desired parameters can replicate the biomechanical properties of the natural bone, thereby overcoming the issues, such as stress shielding effect, to avoid implant failure. The purpose of this research was to investigate the influence of cube and gyroid unit cell types, with pore size ranging from 300 to 600 µm, on porosity and mechanical behavior of titanium alloy (Ti6Al4V) scaffolds. Scaffold samples were modeled and analyzed using finite element analysis (FEA) following the ISO standard (ISO 13314). Selective laser melting (SLM) process was used to manufacture five samples of each type. Morphological characterization of samples was performed through micro CT Scan system and the samples were later subjected to compression testing to assess the mechanical behavior of scaffolds. Numerical and experimental analysis of samples show porosity greater than 50% for all types, which is in agreement with desired porosity range of natural bone. Mechanical properties of samples depict that values of elastic modulus and yield strength decreases with increase in porosity, with elastic modulus reduced up to 3 GPa and yield strength decreased to 7 MPa. However, while comparing with natural bone properties, only cube and gyroid structure with pore size 300 µm falls under the category of giving similar properties to that of natural bone. Analysis of porous scaffolds show promising results for application in orthopedic implants. Application of optimum scaffold structures to implants can reduce the premature failure of implants and increase the reliability of prosthetics.

Emission features, surface morphology and optical limiting properties of semiconducting Toluidine Blue O dye-poly(vinyl alcohol) nanocomposite architecture

Fabrication of a new nanocomposite architecture comprising small weight percentage (< 0.5 wt%) of Toluidine Blue O dye as a filler in host polymer poly(vinyl alcohol) (PVA) via a simple route based on solution-casting is presented. Their microstructure, electrical, linear optical and third-order nonlinear optical properties are introduced here. These samples were characterized as nanocomposites, with dye chromophore uniformly distributed in the molecular chains of the polymer PVA. The effect of fluorescence quenching due to H-aggregates is also discussed. Low threshold third order nonlinear optical response of these nanocomposite film samples was carried out employing the Z-scan technique. With increase in intensity, a transition from reverse saturable absorption to saturable absorption was observed in the nanocomposite films, on excitation with continuous wave (CW) He–Ne laser light. The nonlinear refraction based optical limiting of CW laser light is demonstrated using aperture limited geometry. Compared with other reported results, the estimated values of the nonlinear refractive index (n2), nonlinear absorption coefficients (β), third order nonlinear susceptibility (χ(3)) and limiting threshold are much better. These results thus possess tremendous scope towards future fabrication of optoelectronic and photonic devices such as organic/polymer light-emitting devices, dye-sensitized solar cells, optical limiters, optical switches, etc.

Multicomponent Assembled Systems Based on Platinum(II) Terpyridine Complexes

Platinum(II) terpyridine complexes have received tremendous attention in recent years because of their square-planar geometry and fascinating photophysics. Bottom-up self-assembly represents an intriguing approach to construct well-ordered supramolecular architectures with tunable optical and electronic properties. Until now, much effort has been devoted to the fabrication of monocomponent platinum(II) terpyridine-based assemblies. The next step is to develop multicomponent coassembled systems via the combination of platinum(II) terpyridine complexes with other π-organic and -organometallic molecules. The implementation of electron/energy transfer processes renders advanced functionality to the resulting coassemblies. For the fabrication of discrete multicomponent architectures, a feasible protocol is to construct preorganized molecular tweezers and macrocycles with the involvement of platinum(II) terpyridine complexes as the panel units. In view of their planar surface and positively charged character, such supramolecular receptors are capable of encapsulating electron-rich polyaromatic hydrocarbons and organometallic guests via donor-acceptor charge-transfer and/or metal-metal interactions. Intermolecular hydrogen bonds can be further incorporated between the molecular tweezers receptor and the polyaromatic hydrocarbon guests, giving rise to the strengthened binding affinity and sensitive stimuli-responsiveness. On this basis, multilayer donor-acceptor stacks have been obtained via the precise control over the number of pincers, which feature enhanced complexation strength and superior functionality. Moreover, platinum(II) terpyridine-based macrocycles are more suitable for guest accommodation than the corresponding molecular tweezers receptors in light of their definite size and constrained environment. Stimuli-responsive elements can be conveniently implemented into the rigid spacers of the molecular tweezers and macrocyclic receptors, facilitating the capture and release of the sandwiched guests in a highly controlled manner. On the other hand, long-range-ordered supramolecular polymers have been successfully fabricated with linear, hyperbranched, and cross-linked topologies by employing platinum(II) terpyridine-based molecular tweezers/guest recognition motifs as the non-covalent connecting unit. The degree of polymerization of the resulting donor-acceptor-type supramolecular polymers can be efficiently modulated by incorporating intermolecular hydrogen bonds between the molecular tweezers receptor and the complementary guest unit. An alternative approach toward extended multicomponent donor-acceptor assemblies is to mimic the structure of Magnus' green salt. A delicate balance of non-covalent driving forces between homo- and heterocomplexation processes and a deeper understanding of thermodynamic and kinetic behaviors play the decisive roles in the final arrangement of the coassembled structures. Overall, multicomponent coassembly of platinum(II) terpyridine complexes into well-ordered nanostructures would open up a new avenue toward functional supramolecular materials that are especially promising for sensing, optoelectronics, and catalytic applications.

Post-fire failure mechanisms of seawater-accelerated weathering composites for coastal and marine structures

This paper is the first to examine the mechanical characteristics and the failure mechanisms of seawater-accelerated weathering GFRP composites followed by low intensity fire/heat damage. This work was done to understand how environmental conditions in a marine environment affected mechanical properties before and after low intensity fire damage. E-glass/vinylester composite specimens of angle-ply [±45°/mat]2s and cross-ply [0/90°]3s used in marine and offshore applications were exposed and tested. The effect of fire-induced damage under low heat fluxes (10, 20, and 30 kW/m2) on strength and modulus before and after 120 days of seawater exposure (freeze-thaw cycling in saline solution) is experimentally investigated. A total of 162 samples were tested for shear, tension, and compression. The fabric architectures and seawater exposure influence the post-fire residual properties. A time-dependent mechanical response (pre/post fire exposure) is also presented.

Rethinking IXPs’ Architecture in the Age of SDN

Software-defined Internet eXchange points (SDXs) are a promising solution to the long-standing limitations and problems of interdomain routing. While the proposed SDX architectures have improved the scalability of the control plane, these solutions have ignored the underlying fabric upon which they should be deployed. In this paper, we present Umbrella , a software-defined interconnection fabric that complements and enhances those architectures. Umbrella is a switching fabric architecture and management approach that improves the overall robustness, limiting control plane dependence, and suitable for the topology of any existing Internet eXchange Point (IXP). We validate Umbrella through a real-world deployment on two production IXPs, TouSIX and NSPIXP-3, and demonstrate its use in practice, sharing our experience of the challenges faced.

Enabling direct laser writing of cellulose-based submicron architectures

We report on the first and versatile cellulose-based photoresist, which can be applied in direct laser writing and allows the fabrication of structures with a resolution of less than 1 μm and a feature size of less than 500 nm via two-photon absorption. Therefore, cellulose diacetate is functionalised with methacrylic acid anhydride to introduce photo-crosslinkable side groups into the cellulose chain. The photoresist consists of the methacrylated cellulose diacetate and a photoinitiator both dissolved in acetone. The cellulose-based photoresist can be applied to generate two- and three-dimensional hierarchical structures and clears the way to the design and fabrication of biomimetic architectures solely made from biopolymers. A photo-crosslinkable cellulose-based resist, which can be applied in direct laser writing (DLW), was synthesised. It enables the generation of two- and three-dimensional hierarchical structures with a feature size of less than 500 nm via two-photon absorption. This new photoresist paves the way towards designing and fabricating biomimetic architectures solely made from biopolymers.

Tolnaftate\u2013graphene composite-loaded nanoengineered electrospun scaffolds as efficient therapeutic dressing material for regimen of dermatomycosis

Graphene “The novel carbon nano-trope” tailors auspicious platform for designing antimicrobial regimen by virtue of its conspicuous molecular interaction with the microorganism. In this work, Tolnaftate (Tf), an antifungal drug, was mingled with Graphene nanoplatelets (Gn) to develop composite (Tf–Gn) via the wet chemical route, embedded in a biocompatible polymeric blend of Eudragit RL100/Eudragit RS100 (EuRL100/EuRS100) and subjected to electrospinning to obtain nonwoven nanoengineered scaffolds (nanofibers) for enhanced anti-dermatophytic virtue. Pursuing cluster of optimization experiments, 20% w/v EuRL100/EuRS 100 was found to be adequate for formation of smooth, defect-free, and regular fibers. Field emission electron microscopy (FESEM) acknowledged zestfully fabrication of smooth, shiny, nano-range, and mesh-like architecture, comprising distinct pockets within their structure. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC) conceded formation of the composite Tf–Gn, its physical compatibility with polymers, and improved thermal behavior. Exceptional swelling capacity, significant hydrophilicity, and immense drug entrapment efficiency were obtained of nanofibers fabricated from 3:1 ratio of EuRL100/EuRS100 polymers blend owing to relatively higher permeability which gratified essential benchmark for fabrication of nanofibrous scaffold to alleviate fungal infections caused by dermatophytes. In vitro drug release interpreted controlled liberation of Tf in dissolution media, following Korsmeyer–Peppas model kinetics, and suggested a diffusion-based mechanism. Microdilution broth method was performed for in vitro antifungal efficacy against extremely devastating dermatophytes, i.e., anthropophilic Trichophyton rubrum and zoophilic Microsporum canis, exhibited preeminent growth inhibition against T.rubrum and scanty for M.canis. Findings revealed the superior antifungal activity of Tf–Gn-loaded nanofibers as compared to Tf-loaded nanofibers and recommended potential dressing materials for an effective regimen of dermatomycosis.

Cold Temperature Effects on Consistent and Architecturally Hybridized Woven Kevlar/Epoxy Laminates

The primary objectives of the present experimental research were to characterize and compare the interlaminar mode-I fracture toughness, crack growth and flexural stiffness behaviors of Kevlar KM2-Plus® fiber/epoxy matrix laminates constructed of various woven fabric architectures including plain, 2 × 2 twill and 4H satin weaves at cold [− 46 °C (− 50 °F)] and room [20 °C (68 °F)] temperatures. Secondary objectives were to evaluate and compare the fracture and flexure behaviors for two types of woven laminate constructions referred to as consistent and hybridized laminates. Consistent laminates were constructed with a single fabric weave style throughout all plies and were representative of laminate configurations used in traditional composites design. The hybridized laminates incorporated a mixture of different ply weave styles arranged in a strategic manner to achieve functionally-graded attributes and performance benefits such as enhanced damage tolerance, load carrying capacities, residual strengths and dynamic energy absorption/dissipation levels. The experimental results demonstrated that the interlaminar mode-I critical strain energy release rates, GIc and flexure moduli, Eflex were temperature dependent and that the hybridized laminate provided the optimal combination of highest fracture toughness and bending stiffness with the least sensitivity to temperature. The concept of hybridized laminate architectures can be used to mitigate temperature effects on fracture and flexural stiffness in addition to increasing damage tolerance, load carrying capacities, flexure stiffness, fracture toughness, residual strengths and dynamic energy absorption/dissipation.

Compaction behaviour of tow at meso-scale: experimental investigations of morphological evolution at dry, lubricated and saturated states

Tows, partially constrained (tows within textile architecture) or free (single tows) exhibit movements and deformations, due to the various mechanical solicitations applied during manufacturing. During weaving or stitching, single dry tows undergo local compaction due to interlacing or stitch, leading to the evolution of the tows cross-section while processing. Once the woven or non-crimp fabrics are produced, they are impregnated by a fluid: when considering the infusion process, the filling step leads to a global compressive unloading at macro-scale that modifies, in a saturated state, tows cross-section and tows spatial distribution within the fabric. These evolutions of the fibrous microstructure at mesoscopic scale impact both the mechanical properties and the permeability. Thus, this work proposes two novel experimental methodologies to quantify the morphological evolution of tows under compaction at dry, lubricated and saturated states.

Mechanical modelling of a sheared textile composite unit cell

Composites made using carbon fibre textile reinforcement give an anisotropic material with directional mechanical properties that are dependent on the fabric architecture. The directional properties of a 2D textile are primarily based on weave pattern: The direction of warp and weft yarns, undulation of the tows, and the change in fibre orientation during dry fabric forming process.During dry fabric forming processes, shear is the dominant deformation mechanism as the 2D fabric conforms to 3D shapes. As the fabric changes its shape to match that of the tool, the fibres rotate away from the orthogonal axes as a function of the shear angle. The modified fibre orientation is carried through the curing process and ends up in the finished composite component. This has an influence on the mechanical properties of a cured composite in localised regions of high deformation. Currently the effect of shear during fabric forming is not usually taken into account when modelling the performance of the finished composite at the macro-scale. Through the development of a novel, robust virtual tool, it is possible to identify the change in mechanical properties for a given shear angle. This will allow the macro FE models to give more accurate results. High deformation regions can be identified from a forming simulation (e.g. a sheet of fabric draped over a tetrahedron tool and causes severe shear near the intrusion) and the change in mechanical properties of these local regions can be adjusted accordingly.Using the digital element method previously developed in University of Bristol, the dry fabric architecture can be accurately predicted. The current work has created the ability to shear this virtual unit cell to update the unit cell geometry. This deformed woven geometry is then mapped onto a sheared voxel mesh and combined with an epoxy resin matrix to obtain the meso-scale Representative Volume Element (RVE) model. By applying periodic load cases to the model, the stiffness matrix and therefore the mechanical properties of the composite can be determined. This tool is applicable for any 2D woven resin-infused composite.

Effect of Z-binder tension and internal micro-structure on damage behavior of 3D orthogonal woven composite

The main goal of this study was to investigate the effect of tow tension and related internal micro-structure on the damage behavior of 3D orthogonal woven composites under tensile loading. For representing the internal micro-structure of the composite with respect to varying tow cross-section and the unregulated undulated path which are introduced by Z-binder tension, a dynamical method at filament level which simulates an interlacing process was used to obtain the fabric architecture. Then, an element recognition algorithm was proposed to convert a representative unit cell of 3D woven fabric architectures into a finite element model with 8-node solid elements consisting of four kinds of sets in terms of warp, weft, Z-binder tows and resin matrix. In addition, filament trajectory was also extracted from fabric architecture to serve as a local material orientation. Comparative simulations under tensile loading were conducted on the FEA models generated by this work and texgen software, respectively. An experiment was also carried out to verify the simulation results. The stress–strain curve in the proposed model was found to be closer to the experiment data. The results show that the tensile modulus and strength reduce due to the diverged warp tow path which is induced by the interaction between the tows during the weaving process. Moreover, the irregularity and compressed weft tow cross-sections nearby the intercross point are more likely to generate the transverse damage which would result in the non-linear tensile behavior of the composite material.

Study of braiding commingled self-reinforced PET composites

This work examines the flexural and impact behavior of self-reinforced poly(ethylene terephthalate) (srPET) composites, which were produced by film stacking from fabrics composed of braiding commingled yarns with high-tenacity PET (serving as the reinforcements) and copolymerized PET (mPET) (serving as the matrix). The influence of the hybrid yarns, fabric architectures, and processing conditions on the mechanical properties of srPETs were studied.

Stretchable Electronics: EGaIn‐Assisted Room‐Temperature Sintering of Silver Nanoparticles for Stretchable, Inkjet‐Printed, Thin‐Film Electronics (Adv. Mater. 29/2018)

In article number 1801852, Mahmoud Tavakoli, Carmel Majidi, and co-workers introduce a materials architecture and method for rapid fabrication of electronic tattoos that are highly flexible and stretchable. The tattoos are produced rapidly by combining ink-jetprinted silver nanoparticles with gallium–indium liquid-metal alloy. These ultrathin electronics can be populated with microelectronic components and be mounted on the skin or hydrographically transferred to a wide variety of 3D surfaces.