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Satureja khuzistanica jamzad (SKJ), which is a member of Lamiaceae, has various proven effects such as antispasmodic and anti-inflammatory, anti-diabetic, antioxidant, and antifungal properties. Ho...

Soft morphing actuators can deliver a range of displacements whilst being flexible and lightweight, making them advantageous over traditional mechanical actuators. Piezoelectric polymer polyvinylidene fluoride (PVDF) is combined with nanofillers to achieve superior soft actuator with the nanocomposite than with solely the polymer. This paper investigates and compares the distinctive effects of 1D nanofillers: single-walled carbon nanotubes (SWCNTs) and boron nitride nanotubes (BNNTs), through the promotion of crystal structures and polar β crystals of PVDF, and consequently its actuation ability. Results showed that 80 µm thick 2 wt.% SWCNT/PVDF clamped at both ends with a 10 mm span achieved a high deflection per applied electric field of 414 µm (V mm−1)−1 and deflection of 570 µm. This was due to a combination of fabrication method, physical geometry, and large surface area of SWCNTs leading to enhanced degree of crystallinity, β crystals, dielectric constant, and conductivity. The increase in both overall crystal formation and targeted β crystals lead to a high total β crystal content of 35%, and the conductivity lead to a low applied electric field of 1.3 V mm−1. BNNT/PVDF was able to undergo electric poling due to its insulating nature. BNNT/PVDF achieved a deflection magnitude per applied electric field of 2.9 µm (V mm−1)−1, due to a much higher electric field (90–150 V mm−1). This corresponded to a deflection magnitude of 260 µm, which was a 520% increase from only stretched BNNT/PVDF samples. Both nanocomposites displayed large scale actuation that is greater than the 70 µm deflection (0.9 µm (V mm−1)−1) observed for pure PVDF of same geometry and setup.

Abstract: Staphylococcus aureus is a human pathogen causing nosocomial infections and increased hospitalization and mortality among human communities. Methicillin-resistant S. aureus strains are considered a severe threat in nosocomial infections and cause complications in the remedy process of bacterial infections. In this study, 137 samples were collected from different departments, staff, and patients in Ilam hospital. Eighty-eight samples of these strains were examined to test antibiotic resistance and diffusion. MIC (minimum inhibitory concentration) and PCR (polymerase chain reaction) were performed on the samples resistant to oxacillin. 36 (40.9%) strains were MRSA, and 52 (59.1%) isolates were MSSA. 44.4% of MRSA strains with IV SCCmec type. Fourteen different spa types were found using spa typing, of which the most abundant types were t037, t030, and t701, and three new types, including t15471, t15474, and t17470, were identified among the strains. The molecular analysis by MLST showed that the strains are classified into 11 different sequence types. Sequence type 239 and clonal complexes of 329 and 22 were dominant. ST239-spat037-SCCmec III was also identified as the most frequent clone of MRSA. The most identified clones were MRSA ST239-spa t037-SCCmec III. The results show the spa-type distribution between samples of patients, personnel, and surfaces, demonstrating MRSA circulation between patients and the environment. The results show the need to control environmental health

To evaluate the anti-bacterial activities of titanium dioxide (TiO) nanoparticles of Origanum (O.) vulgare and Hypericum (H.) perforatum extracts, carvacrol and hypericin against Staphylococcus (S.) aureus.In this study, TiOnanoparticles of O. vulgare and H. perforatum extracts, carvacrol and hypericin, were prepared and their antibacterial effects were evaluated against Staphylococcus (S.) aureus. In this study, scanning electron microscope, fourier transform infrared spectrometer, atomic force microscopy, dynamic light scattering and zeta potential were used to investigate the structure of synthesized drugs.Anti-bacterial activity of synthesized NPs was tested by minimum inhibitory concentration (MIC), minimum bactericidal concentration and disc diffusion method. MICs of TiO-NPs synthesized using O. vulgare, H. perforatum, carvacrol and hypericin and TiO were obtained 250, 62.5, 250, and 250, and 500 μg/mL, respectively. The MBCs for all of these were obtained 1000 μg/mL.Green-synthesized of TiO nanoparticles provides a promising approach to the use of O. vulgare and H. perforatum, carvacrol and hypericin as novel agents and safer antibacterial compounds, especially anti-S. aureus compounds.

Nepeta curvidens is a plant of the mint family and an important species of the genus Nepeta. The main habitat of the N. curvidens in the Garin Mountains in Lorestan Province, Iran. Although locals have used N. curvidens as a food flavoring agent for years, few studies have been conducted on its phytochemical and biological properties. The chemical constituents of N. curvidens essential oil and then its biological properties were studied in detail in this investigation. N. curvidens essential oil was prepared from the aerial parts of the plant using the hydrodistillation method and its chemical composition was analyzed by the GC-MS method. Antimicrobial, antifungal, anti-Leishmania, and cytotoxic activities of the essential oil were investigated in vitro. In addition, antinociceptive and anti-inflammatory effects were evaluated in vivo. Most of N. curvidens essential oil compositions are composed of trans-caryophyllene (17.53%), allo-spathulenol (13.41%), germacrene D (10.12%), bicyclogermacrene (9.36%), α-pinene (9.12%), and β-phellandrene (6.87%). The highest antimicrobial and antifungal effects were observed against L. monocytogenes (MIC=156.25 μg/ml) and K. marxianus (MIC=625 µg/ml), respectively. Concentration-dependent effects were detected in the treatment of L. major, so that the number of macrophages infected with amastigote dropped significantly with higher concentrations. The essential oil showed the highest effect on the lung cancer cell line (A549) with the lowest IC50 (133.2μg/mL). The most resistant cell line to the essential oil was bladder cancer (C450) with an IC50 of 430.69 µg/mL. SI 19.49 index indicated high immunity of the essential oil on macrophage lines. Compared with morphine analgesic, the highest pain control effect of the essential oil was observed in primary and secondary phases at 100 mg/kg concentration in rats. At 100 mg/kg concentration, reduced swelling of the paw and ear was observed in mice compared to the dexamethasone anti-inflammatory drug. The essential oil presents remarkable therapeutic properties such as antifungal, antibacterial, anti-inflammatory properties that probably attributed to the presence of an important trans-caryophyllene compound. Outstandingly, the essential oil has low toxic effects on the normal line and high antitumor properties against cancer cells. Therefore, it is expected to be used in the preparation of less toxic drugs than chemical ones, although more studies are required.

Background Previous studies have reported that quercetin (Q) has a potential antibacterial and anticancer activity. However, its application is limited by many important factors including high hydrophobicity and low absorption. Methodology In the current study, we synthesized and characterized (Patent) a novel chitosan-based quercetin nanohydrogel (ChiNH/Q). Encapsulation efficiency was confirmed by UV/VIS spectrophotometer. Physicochemical characterization of ChiNH/Q was assessed by PDI, DLS, SEM, FTIR, and XRD. The toxicity of the ChiNH/Q against five strains of the pathogen and HepG2 cells was examined. Moreover, the quantification of ChiNH/Q on genomic global DNA methylation and expression of DNMTs (DNMT1/3A/3B) in HepG2 cancer cells were evaluated by ELISA and real-time PCR, respectively. Results Under the SEM-based images, the hydrodynamic size of the ChiNH/Q was 743.6 nm. The changes in the PDI were 0.507, and zeta potential was obtained as 12.1 mV for ChiNH/Q. The FTIR peak of ChiNH/Q showed the peak at 627 cm-1 corresponded to tensile vibrational of NH2-groups related to Q, and it is the indication of Q loading in the formulation. Moreover, XRD data have detected the encapsulation of ChiNH/Q. The ChiNH/Q showed a potent antimicrobial inhibitory effect and exerted cytotoxic effects against HepG2 cancer cells with IC50 values of 100 µg/mL. Moreover, our data have shown that ChiNH/Q effectively reduced (65%) the average expression level of all the three DNMTs (p

Pseudotrachydium kotschyi is a native medicinal plant used as a local medicine from Lorestan province of western Iran having numerous biological properties. After GC−MS analysis of Pseudotrachydium kotschyi essential oils (PKEOs), some biological activities were investigated. Additionally, TNF-α and TGF-β1 were studied in Leishmania-infected macrophages (in vitro) and Carrageenan-induced paw edema in rats. Finally, anti-inflammatory and wound-healing potential of PKEOs were investigated in vivo in mice. Total components identified by GC−MS contained 53 molecules, among which Z-α-trans-Bergamotol (23.25%), Durylaldehyde (16.07%), and α-Bergamotene (10.48%) existed in the highest amount in PKEOs. Antimicrobial assay of PKEOs showed maximum growth inhibition against Listeria monocytogenes and Kluyveromyces marxianus at the dose of 625 μg/ml. PKEOs exhibited a high cytotoxicity on lung cancer cell line A549 at a dose of 4 mg/ml. Anti-Leishmania activity of PKEOs showed concentration of 5000 µg/ml that had similar potency of glucantime at 125 µg/ml. The highest anti-inflammatory effect of PKEOs for Carrageenan-induced paw edema was observed at 100 concentrations, with paw inflammation reduced by 83.70% after using PKEO ointment. The present study reports broad-spectrum biological functions for essential oil from P. kotschyi. However, these biological activities, including anti-proliferative, anti-Leishmania, anti-inflammatory, antimicrobial and wound-healing potential, were not studied in detail. Therefore, it may be attractive for investigating the detailed mechanistic and molecular aspects of biological activities of PKEOs. Considering that the present study is the first to report the biological activity of P. kotschyi, further studies on their metabolites are needed to replicate the present findings.

Ceramics possess desirable stiffness, compressive strength, and thermal properties compared to alternative material classes. Despite this, the adoption of ceramics into advanced industries has been hindered by their inherent brittleness. Using a state-of-the-art manufacturing platform, the authors incorporate disordered microstructural features inspired by those found in natural, impact-resistant organisms using tessellated ceramic cells. To precisely mimic these natural patterns, a disorder parameter is introduced to modulate the stochasticity of the ceramic architectures. By modifying simple geometrical features such as cut depth and the disorder parameter, the energy absorption is dramatically improved, and the stiffness of the system can be tailored. It is found that the stochastic designs exhibit elevated damage tolerance, denoted by higher dynamic energy absorption (up to 330% for the 3rd impact) and stiffness (up to 200% for the 3rd impact) than both monolithic and perfectly hexagonal architectures. The results show a superior multi-hit resistance owing to optimal cut depth and stochasticity which give access to extrinsic toughening mechanisms that can be influenced through design parameters. This highly-scalable, digital manufacturing platform for creating numerically programmable architectures propels the automated production of intelligent, high-performance, and tailorable ceramic systems for industrial applications in aerospace, protective devices, and medicine.

Background: Nanoparticles (NPs) are colloidal systems with particles ranging from 10 to 100 nm in diameter. Because of their large surface-volume ratio, NPs are biologically active materials that could interact with biomolecules and microorganisms, enter into the cells, and affect the metabolic functions. The study aimed to biosynthesize silver nanoparticles (Ag-NPs) from Capparis spinosa fruit aqueous extract, and evaluate their Ag nanostructure characterization and antifungal activity. Materials and Methods: Capparis spinosa fruit aqueous was prepared with the percolation method. Then, silver NPs were synthesized using 0.01 M silver nitrate solution, and their formation was validated by color changing of the solution from green to dark brown . The NPs were purified using centrifugation and then dried in an oven for further analyses. Ag-NPs nanostructure characterization was determined by various techniques such as Fourier Transforms Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM), and Ultraviolet-visible (UV-Vis) spectroscopy. Antifungal activity of Ag-NPs against three pathogenic fungi of Candida albicans, Candida glabrata, and Kluyveromyces marxianus was also evaluated using the microdilution method. Results: Synthesis of Ag-NPs from aqueous extract of C. spinosa fruit was done successfully. UVVis spectrum of Ag-NPs showed an absorbance peak around 420 nm, revealing Ag-NPs surface plasmon resonance (Kmax). FTIR analysis showed that functional groups correspond to plant bioactive components, promoting the formation of Ag-NPs. Furthermore, spherical uniformity of the synthesized Ag-NPs from plant extract was confirmed by SEM analysis within the 50-80 nm size range. Our results showed that the produced Ag-NPs were spherical and in a suitable form and size (50-80 nm). The biosynthesized Ag-NPs had an inhibitory effect against all tested fungi with the minimum inhibitory concentration of 2500, 5000, and 625 μg/mL and minimum bactericidal concentration of 10000, 10000, and 156.25 μg/mL for C. albicans, C. glabrata, and K. marxianus, respectively. Conclusion: According to the UV-Vis spectrum, FTIR, and SEM results, we succeeded in synthesizing Ag-NPs from C. spinosa fruit aqueous extract. This research was the first report of Ag-NPs synthesized from aqueous extract of C. spinosa fruit. Our simple, quick, and inexpensivemethod for biosynthesis of a nanoparticle, which showed antifungal activity, provides a new potential antifungal agent for therapeutic applications.

Carbon nanotubes (CNTs) possess impressive properties along with low density. Integration of CNTs in the form of fabrics or other preformed assemblies simplifies their handling and allows for the higher CNT content needed to better leverage their properties in multifunctional structures. Here we describe production of non-woven CNT-polyurethane fabrics made from industrial-grade CNTs via a one-step filtration method. Individual sheets were scaled to 30 cm x 30 cm size and subsequently used to fabricate thicker composites, including via lamination with itself to produce simple panels and with other materials to further tailor the nanocomposite properties and address several example applications including electrical heating, fire resistance, electromagnetic shielding, and a skin for stretchable morphing structures.

Objective: Staphylococcus aureus, a Gram-positive bacteria, is ranked second among the causes of hospital infections and is one of the three main causes of food poisoning. In recent times, the spread of antibiotic resistance in S. aureus has become very worrisome. Therefore, research for new effective drugs is important. The present study aims to investigate the phytochemical profiles and antibacterial effects of hydroalcoholic extracts of Origanum vulgare (Lamiaceae family) and Hypericum perforatum (Clusiaceae family) and their active compounds on S. aureus (ATCC 12600) in vitro. Methods: The identification of phytochemical compounds in both plants was performed by Highperformance liquid chromatography (HPLC), headspace-solid-phase microextraction (HS-SPME) and Fourier-transform infrared spectroscopy (FTIR). To investigate microbial susceptibility, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and disc diffusion method (DAD) were used. Finally, the results of the study were compared with methicillin. Results: Of the 42 combinations of O. vulgare, carvacrol (48%) and of the 38 combinations of H. perforatum, hypericin (46.2%) were the most abundant. The MIC, MBC and DAD of O. vulgare and H. perforatum, carvacrol, hypericin and methicillin were 625, 625, 312.5, 78.12 and 384 µg/mL, 10000, 10000, 2500, 2500 and 384 µg/mL, and 15.66 ± 4.49, 12.66 ± 0.47 and 22 ± 0.81 mm, respectively. Conclusion: Due to the significant effects of O. vulgare and H. perforatum and their active components against S. aureus, it is expected that in the future, hypericin, carvacrol and their derivatives can be used as effective antibacterial agents against S. aureus.

Precise material architectures and interfaces can generate unusual and attractive combinations of mechanisms and properties. For example, the segmentation into blocks of finite size and well-defined geometries can turn brittle ceramics into tough, deformable and impact resistant material systems. This strategy, while scarcely used in engineering, has been successfully used for millions of years in biological materials such as bone, nacre or tooth enamel. In this work, the precise relationships between architecture, mechanics, and properties in architectured ceramic panels are explored using a combination of mechanical testing with stereo-imaging, 3D reconstruction, and finite-element/analytical modeling. In particular, this work shows that a fine balance of interlocking and block size generates controlled frictional sliding and rotation of blocks, minimizes damage to individual blocks and optimizes performance. These ceramic architectured panels have 1/4 to 1/2 of the strength of monolithic ceramic panels, but they can absorb 5 to 20 times more mechanical energy, making them very attractive for applications where high surface hardness or high resistance to temperature must be combined with resistance to impact and toughness.

The increasing use of polymer nanocomposites in armor applications requires an understanding of how these materials behave at strain-rates relevant to ballistic impacts. Of particular interest is the role of the microstructure on the failure of these materials under dynamic tensile loading. In the present study, plate impact experiments were conducted in order to measure the spall strength of a neat epoxy (EPON 828) and an epoxy–carbon nanotube composite. The addition of pristine carbon nanotubes (CNTs) to the epoxy resulted in a composite material with a lower spall strength than the neat epoxy matrix material. Recovered composite fragments were imaged with a scanning electron microscope. Instances of nanotube pull-out were identified on internal fracture surfaces. The lower spall threshold of the epoxy–CNT composite was attributed to the comparatively weak epoxy–CNT interface, which provides potential sites from which spall failure can favorably nucleate.

Brittleness is a major limitation of polymer-derived ceramics (PDCs). Different concentrations of three nanofillers (carbon nanotubes, Si3N4 and Al2O3 nanoparticles) were evaluated to improve both toughness and modulus of a commercial polysilazane (PSZ) PDC. The PSZs were thermally cross-linked and pyrolyzed under isostatic pressure in nitrogen. A combination of mechanical, chemical, density, and microscopy characterizations was used to determine the effects of these fillers. Si3N4 and Al2O3 nanoparticles (that were found to be active fillers) were more effective than nanotubes and improved the elastic modulus, hardness, and fracture toughness (JIC) of the PDC by ~ 1.5 ×, ~ 3 ×, and ~ 2.5 ×, respectively. Nanotubes were also effective in maintaining the integrity of the samples during pyrolysis. The modulus and hardness of PDCs correlated positively with their apparent density; this can provide a fast way to assess future PDCs. The improvement in fracture toughness was attributed to crack deflection and bridging observed in the micro-indentation cracks in the modified PDCs. The specific toughness of the modified PDCs was 4 × higher than that of high-purity alumina, and its specific modulus reached that of commercially available technical ceramics. These PDCs can also easily take different shapes and therefore are of interest in protective armor, propulsion, thermal protection, device packaging and biomaterial systems.

Ceramics offer many attractive properties including low-density, high compressive strength, remarkable thermal stability, and high oxidation/corrosion resistance. However, these materials suffer from brittleness, which substantially limits the range of their applications, where high toughness is required. This investigation draws inspiration from a concept of architectures with three-dimensional (3D) networks of weak interfaces targeting high toughness ceramics. In this study, a comprehensive method combining an advanced computational model with 3D digital image correlation (DIC) was developed to engineer bioinspired multilayered architectured ceramics and assesses their toughening and deformation mechanisms when subjected to a low-velocity impact load regime. A complete finite element (FE) analysis was conducted to precisely evaluate the crack growth and displacement field of the architectured ceramics and is compared to those of plain ceramics. The damage and displacement evolution results from FE analysis and experimental testing revealed that the primary source of toughening of the architectured ceramic systems is extrinsic, resulting from extensive crack deflection and delamination. Crack propagation along an irregular long path at the weak interfaces of architectured layers increased the toughness of the plain ceramics by two orders of magnitude. Based on the DIC data, both extrinsic and intrinsic toughening mechanisms were captured: sliding of the tiles in the architectured ceramics and channel plastic deformation in adhesive interlayers, respectively.

Traditional machining techniques pose significant drawbacks when applied to ceramics due to the material’s inherent brittleness. Specialized laser machining has been known to solve these issues through higher precision and micrometer-scale feature control. In this study, a picosecond fiber laser has been proposed as a near-net shaping material removal system for different engineering applications of industrial grade alumina ceramics with a variety of thicknesses and feature dimensions. This article particularly focuses on optimizing picosecond laser processing parameters (i.e., wobble amplitude, wobble frequency, wobble pitch, linear speed and number of passes) that were implemented to obtain ablated, deep, smooth and defect-free designed cut geometries (i.e., kerf taper and cut depth) with a high degree of precision. The surface roughness was assessed to determine the quality of the cuts. The optimal process parameters between the quality and material removal rate were introduced. Using a circular wobble laser pattern, it was determined that a greater cut depth can be achieved at lower linear speeds and wobble frequencies due to the higher linear energy density. It has also been found that the kerf taper is dependent on the cut depth and wobble amplitude, where the measured cuts follow the geometric relation between these parameters accurately. In addition, a maximum material removal rate of ~ 10 mm3/min was achieved to make a desired ablated cut profile in the alumina ceramic tiles as thick as 2.54 mm (0.1 in).

Architectured materials/structures provide avenues as a robust design strategy to enhance the strength and toughness of brittle materials. Architectured materials and interfaces can transform brittle ceramics into impact resistant structures with tunable toughness, strength and stiffness. In this work, we have developed a fast, simplified and industrially scalable fabrication technique based on laser machining for large-scale architectured ceramics. Utilizing this technique, a new class of advanced ceramics based on bio-inspired architectures have been designed to improve and tune the mechanical response in multi-impact conditions. The multilayered ceramics were manufactured by stacking laser-cut hexagonal tiles (with differing cut depths) and interlayers made of the commercial monomer Surlyn®. Stereo/3D laser scanning microscopes and nondestructive evaluation (NDE) techniques including infrared thermography, X-ray radiography and X-ray penetrant inspection were used to assess the architectures before and evaluate the multiscale damage after each impact. It was found that the multilayered architectured ceramic systems with a partial-cut depth (i.e., 40% and 70%) exhibited higher dynamic energy absorption performance (up to 220% for the 3rd impact) and higher stiffness (up to 80% for the 3rd impact) than the multilayered plain ceramic. The results showed a bell-shaped response in the partial-cut architectured ceramics, indicating tough materials (opposed to the plain one) and superior multi-hit resistance owing to the energy dissipation mechanisms including plastic deformation in adhesive interlayers and inter-cuts, crack deflection, frictional energy dissipation due to tile sliding (absent toughening mechanisms in the plain system) as well as ceramic fracture upon flexural cracks in the partial-cuts and delamination crack (absent mechanisms in the 100% cut-depth architectured system).

Electrothermal actuator (ETA) is an area of smart and active materials that is being heavily researched to utilize their large strain capabilities. Traditionally, these actuators are fabricated by coating a polymeric soft elastomer onto a layer of conductive fillers such as buckypaper. This paper explores various factors that can influence the actuation performance including, but not limited to, electrical conductivity, sample thickness, addition of insulation layers, and spatially varying conductance zones. While conventionally, small and thin film-like ETA structures with uniform heating distributions are used, this paper proposes scalable ETAs by fabricating larger ETAs with spatially varying conductance zones.

Ceramics possess high thermal and chemical resistance, low density, and high compressive strength; however, the machining complications imposed by their inherent brittleness limit their range of applications. Laser cutting technology can offer an automated manufacturing technique for machining these brittle materials. In this paper, a laser cutting method, so-called wobbling, was developed for performing deep, high precision, and defect-free laser cutting of industrial grade alumina ceramics. This work explored picosecond laser process parameters such as focal position, linear speed, and wobble amplitude in order to control cut depth and optimize cut quality in terms of kerf width, kerf taper, surface cleanness, while avoiding crack formation. The morphology and cut quality were evaluated using 3D laser scanning microscopy and scanning electron microscopy (SEM). Picosecond laser cutting process parameters were optimized, achieving a maximum material removal rate of ~10 mm3/min. It was shown that the laser cutting process developed via these experiments represents an effective and efficient manufacturing tool that can be incorporated in engineered net shaping systems.

Boron nitride nanotubes (BNNTs) offer complimentary properties to carbon nanotubes (CNTs) and interact more favorably with epoxies than do CNTs. This could make BNNTs the preferred nanotube for reinforcing epoxy when electrical conductivity is not required, and particularly where features such as transparency/color, neutron absorption or electrical insulation are advantageous. Here we report epoxy nanocomposites containing 1–7 wt% raw BNNTs. The elastic modulus and fracture toughness increased progressively with loading up to 5 wt% BNNTs. Adhesive joints (ASTM D1002) indicated average improvements of ~10% in joint strength at 2 wt% raw BNNTs, but substantially reduced strength for a 5 wt% BNNT adhesive joint. Observation of the failure surfaces suggests that BNNTs impede crack propagation leading to increased joint performance despite a mixed-mode failure with a substantial contribution from adhesive failure. BNNTs purified by removing the elemental boron impurity were more effective, yielding 15% joint strength improvements at 1 wt% loading. This nanocomposite is also semi-transparent, showing the potential for reinforced, electrically insulating, transparent adhesives based on BNNTs.

Matrix enhancement using nanotubes is one method to produce hybrid, multiscale fiber reinforced polymer (FRP) composites with improved interlaminar performance and added functional properties. Carbon nanotubes (CNTs) have been shown to be promising, and recent advances in the manufacturing of boron nitride nanotubes (BNNTs), which are largely unexplored for structural reinforcement of hybrid composites with microscale fibers, offer new opportunities to employ BNNTs in reinforced hybrid composite structures. This study investigates the shear and impact properties of BNNT hybrid composites, specifically glass fiber–epoxy/BNNT composite laminates. Two manufacturing techniques were used to fabricate the specimens: wet layup and vacuum-assisted resin transfer molding (VARTM). Shear punch, short beam shear, and modified Charpy tests were selected for their relevance to complex loading systems that involve shear, such as ballistic or other impact loading. The addition of 1 wt % BNNTs to the epoxy resin was found...

Topologically interlocked architectures can transform brittle ceramics into tougher materials, while making the material design procedure a cumbersome task since modeling the whole architectural design space is not efficient and, to a degree, is not viable. We propose an approach to design architectured ceramics using machine learning (ML), trained by finite element analysis data and together with a self-learning algorithm, to discover high-performance architectured ceramics in thermomechanical environments. First, topologically interlocked panels are parametrically generated. Then, a limited number of designed architectured ceramics subjected to a thermal load is studied. Finally, the multilinear perceptron is employed to train the ML model in order to predict the thermomechanical performance of architectured panels with varied interlocking angles and number of blocks. The developed feed-forward artificial neural network framework can boost the architectured ceramic design efficiency and open up new avenues for controllability of the functionality for various high-temperature applications. This study demonstrates that the architectured ceramic panels with the ML-assisted engineered patterns show improvement up to 30% in frictional energy dissipation and 7% in the sliding distance of the tiles and 80% reduction in the strain energy, leading to a higher safety factor and the structural failure delay compared to the plain ceramics.

The properties of a two-part epoxy resin and GFRP laminates enhanced with high contents of graphene are evaluated. The effect of graphene on the thermomechanical and tensile properties of the resin are studied. An RTM processing window is developed to manufacture laminates. Graphene dispersion is evaluated with optical microscopy and SEM. The flexural properties show an improvement of up to 16% while the thermal conductivity shows an improvement of up to 52% in the transverse direction. The impact performance is negatively affected by 22%. Microscopy shows graphene agglomerates in the composite, explaining the lack of improvement in the electrical conductivity. Thermal conductivity is improved while keeping the insulating properties of the composite which is desirable in applications such as battery retainers and electronic applications. A combination of solvent-free, high-shear mixing of high content graphene-enhanced resin (e.g., 10 wt%) and RTM can be used as an scalable process to produce complex parts.

Despite being porous, natural materials such as bone, nacre and tooth enamel possess interesting combinations of stiffness, strength and toughness, an outstanding performance which is hard to achieve in engineering materials. Recent studies show that this performance is rooted in their architectures in which stiff and strong inclusions are arranged in a staggered structure and placed within a softer matrix. These studies however focus on void-free staggered composites. Here, we use finite element analysis and exhaustive exploration of the design space to show that the specific modulus and yield strength of staggered composites can be improved by removing the non-load bearing regions of the matrix material and to show the morphologies emerging from this process. This improvement increases with aspect ratio of the inclusions and with mismatch of properties between the phases and decreases with inclusion content. Particularly, 20–30% increase in the specific modulus and 10–20% increase in specific yield strength can be achieved considering the actual properties of carbon nanotube (or ceramic/mineral platelet) reinforced polymers. The morphologies emerging from our exploration can be used to develop lightweight composites of interest in aerospace, defence, and packaging industries.

We have fabricated carbon nanotube (CNT)-polyurethane (TPU) sheets via a one-step filtration method that uses a TPU solvent/non-solvent combination. This solution method allows for control of the composition and processing conditions, significantly reducing both the filtration time and the need for large volumes of solvent to debundle the CNTs. Through an appropriate selection of the solvents and tuning the solvent/non-solvent ratio, it is possible to enhance the interaction between the CNTs and the polymer chains in solution and improve the CNT exfoliation in the nanocomposites. The composition of the nanocomposites, which defines the characteristics of the material and its mechanical properties, can be precisely controlled. The highest improvements in tensile properties were achieved at a CNT:TPU weight ratio around 35:65 with a Young’s modulus of 1270 MPa, stress at 50 % strain of 35 MPa, and strength of 41 MPa, corresponding to ~10 fold improvement in modulus and ~7 fold improvement in stress at 50 % strain, while maintaining a high failure strain. At the same composition, CNTs with higher aspect ratio produce nanocomposites with greater improvements (e.g. strength of 99 MPa). Electrical conductivity also shows a maximum near the same composition, where it can exceed the values achieved for the pristine nanotube buckypaper. The trend in mechanical and electrical properties was understood in terms of the CNT-TPU interfacial interactions and morphological changes occurring in the nanocomposite sheets as a function of increasing the TPU content. The availability of such a simple method and the understanding of the structure-properties relationship are expected to be broadly applicable in the nanocomposites field.

Surface functionalized boron nitride nanotubes (f-BNNTs) with hydroxyl (OH) and amino (NH2) groups are employed as a nanofiller to reinforce polycarbonate (PC), a resin that has widely been used where a combination of transparency and high energy absorption is required, such as in armor, automotive and display technologies. To improve the interfacial compatibility of BNNTs with the PC matrix, BNNTs are treated with bromine in water inducing B N bond cleavage and subsequent formation of OH and NH2 functional groups on BNNT-surfaces. Samples of 1, 2 and 4 wt% f-BNNT/PC nanocomposite are prepared in a mixture of chloroform and dimethylformamide (DMF). The resulting f-BNNT/PC nanocomposites are processed in two ways: thin film formation from the powder by using a hot-press and plaque formation through melt-mixing-extrusion and compression molding techniques, respectively. The thermal and mechanical properties of the f-BNNT/PC nanocomposites are evaluated and compared with those of neat PC. They exhibit about 4∼8 °C improvement in thermal stability and over 30 °C higher in anti-oxidation than those of the neat PC. The testing result reveals that the f-BNNT/PC nanocomposite at 1 wt% loading achieves 39% increase in tensile toughness relative to the neat PC. Young’s modulus has an improvement by 13% (1 wt%) and 31% (4 wt%), respectively, from the thin-film samples; while about 2% and 13% improvements are observed from the extruded coupons at the same f-BNNT loadings. The transparency of the thin films is shown to decrease with the increase of f-BNNT loading.

Boron nitride nanotubes (BNNTs), like carbon nanotubes (CNTs), possess an impressive collection of properties that motivate their use in composite materials, particularly in areas where CNTs are limited (e.g., high-temperature processing and applications) or unsuitable (e.g., electric insulation). The recent advent of pilot-scale production and of commercial BNNT materials offers improved opportunities to study BNNT science and develop BNNT-based composites and applications. Here, we highlight recent advances in BNNT manufacturing and commercialization and the properties and performance of BNNT-based nanocomposites including polymer, metal, and ceramic composites and envision a future landscape of BNNT applications.

Aim: This study was designed to evaluate the synergistic activities of hydroalcoholic extracts of medicinal plants Origanum vulgare and Hypericum perforatum and their active components, carvacrol and hypericin against Staphylococcus aureus. Methods: The synergistic effects of the plants, as well as carvacrol and hypericin, were examined using a checkered method against S. aureus (ATCC 12600). Results: A fractional inhibitory concentration of 0.5 was obtained for combination of O. vulgare and H. perforatum and 0.49 for combination of the active ingredients carvacrol and hypericin, both of which indicated a synergistic effect. Conclusion: This preliminary evaluation demonstrated a synergistic property of O. vulgare and H. perforatum extracts in treating S. aureus infection. This study indicates that combination of the plants, as well as combination of carvacrol and hypericin, might be used as a new antibacterial strategy against S. aureus., Lay abstract We studied and evaluated the synergistic activities of hydroalcoholic extracts of oregano and St John's wort and their active components, carvacrol and hypericin, against Staphylococcus aureus. The results suggest that a combination of oregano and St John's wort extracts, as well as a combination of hypericin and carvacrol, have potential for use as natural and effective combinations against S. aureus infections.

Adaptive structures and morphing aircraft technologies have generated much interest in the aerospace community, including regular sessions at AIAA conferences. However, due to the lack of suitable materials to make stretchable structures with loadbearing ability, relatively few works address the development of morphing wings that undergo substantial area change despite the advantage of doing so for the aerodynamic performance. At SciTech 2018 we first presented an approach to development of a stretchable skin based on carbon nanotube-polyurethane sheets with approximately 25 wt.% carbon nanotubes. In this paper we describe the production and properties of the nanocomposite skin, a complimentary support structure produced via structural optimization and 3D printing, and integration of these components along with a custom-designed actuation mechanism within a 25 cm wide, 200 cm long benchtop-scale morphing leading edge demonstration., AIAA Scitech 2019 Forum, January 7-11, 2019, San Diego, CA, USA

The thermal conductivity of bulk, self-supporting boron nitride nanotube (BNNT) sheets composed of nominally 100% BNNTs oriented randomly in-plane was measured by a steady-state, parallel thermal conductance method. The sheets were either collected directly during synthesis or produced by dispersion and filtration. Differences between the effective thermal conductivities of filtration-produced BNNT buckypaper (∼1.5 W m−1 K−1) and lower-density as-synthesized sheets (∼0.75 W m−1 K−1), which are both porous materials, were primarily due to their density. The measured results indicate similar thermal conductivity, in the range of 7–12 W m−1 K−1, for the BNNT network in these sheets. High BNNT-content composites (∼30 wt.% BNNTs) produced by epoxy impregnation of the porous BNNT network gave 2–3 W m−1 K−1, more than 10× the baseline epoxy. The combination of manufacturability, thermal conductivity, and electrical insulation offers exciting potential for electrically insulating, thermally conductive coatings and packaging. Thermal conductivity of free-standing BNNT buckypaper, buckypaper composites, and related materials at room temperature.