Potential In Several Applications Research Articles

Nanoparticles of ZrO2:xSr2+ produced by the sonochemical method: Structural, morphological, and photoluminescent characterization for optoelectronic applications

The pursuit of efficient materials for technological applications is essential. Among these materials, zirconia emerges as a promising candidate with potential for several applications, from applications related to mechanical resistance to optoelectronic applications. By introducing dopants into this compound, it becomes feasible to modulate its inherent properties. In this study, ZrO2 doped with strontium was synthesized for the first time via the sonochemical method at different percentages in mol (1, 2, 4, and 8 mol%). Analysis via X-ray diffraction (XRD) and Raman spectroscopy unveiled the formation of both monoclinic and tetragonal phases, with the latter being stabilized through the incorporation of the dopant element. In addition to observing irregular morphology through scanning electron microscopy (SEM-FEG), a reduction in particle size was also evidenced following the introduction of Sr2+ ions, a phenomenon corroborated via Rietveld refinement. The reflectance spectra of the doped samples exhibited an optical absorption tail characterized by the Urbach energy (EU), indicating an increase in structural disorder in the samples. The photoluminescence (PL) results indicated that the introduction of Sr2+ ions into the ZrO2 matrix induced modifications in the characteristics of the spectrum profile. The phase transformation observed in XRD was reflected in the changes observed in the photoluminescent behavior of the samples, which emitted light between the blue and green regions.

DFT validation of thermodynamic modeling and phase relations of equilibrium experimentation on the pseudo-ternary system Al2O3–CaO–Cr2Ox

Despite great potential in several applications, the pseudo-ternary system Al2O3–CaO–Cr2Ox is an overlooked phase diagram due to the formation of a few toxic, carcinogenic, and water-soluble Cr6+ compounds. In the research paper, equilibrium experimentation of selected compositions was conducted at 1073, 1373, and 1673 K and investigated using XRD, SEM-EDS, and leaching tests. Further, thermodynamic modeling of limited databases of the pseudo-ternary system Al2O3–CaO–Cr2Ox was validated using DFT calculations. Including the recently discovered novel phase CaAl2Cr2O7 (wuboraite), the seven phases not available in the SGTE SUBstance (SSUB) database, along with the CaCrO4 and CaCr2O4 phases existing therein, were modeled using Density Functional Theory (DFT). Based on the above experiments and the present CALPHAD model, we have calculated the isothermal sections (1073, 1373, and 1673 K) of the Al2O3–CaO–Cr2Ox system for different oxygen partial pressures (P(O2)= 0.21 atm and P(O2)= 10−8 atm).

Novel epoxy/cyclic olefin copolymer/carbon structural composites with electro‐activated self‐healing properties

AbstractMultifunctional self‐healing composites have great potential in several applications, i.e., from automotive to aerospace. This study examines the self‐healing behavior of carbon fiber reinforced composites by depositing jet‐spun cyclic olefin copolymer (COC) meshes on dry carbon fiber plies before lamination with epoxy resin (EP). Three different laminates were prepared, including neat EP/CF and two composites with 4 wt.% and 8 wt.% of COC in the form of a jet‐spun network as a healing agent. The introduction of COC mesh reduced flexural stress by 26% and interlaminar shear strength by 50%. Mode I interlaminar fracture toughness (GI) was evaluated and specimens were mended at 110°C by resistive heating generated by an electrical current flowing within the samples. The laminates containing 8 wt% COC reported a healing efficiency, evaluated as the ratio between the GI and as the ratio of the maximum load (PMAX) of virgin and healed samples, of 9.4% and 33.7%, respectively. Fractography analysis highlighted the poor adhesion between the COC mesh and EP matrix, and several COC microfibers were trapped inside the epoxy matrix, hindering their diffusion inside the crack zone, which limited the healing capability of the prepared laminates.

Effects of Transition Metals on Metal-Octaaminophthalocyanine-Based 2D Metal-Organic Frameworks.

Metal-octaaminophthalocyanine (MOAPc)-based 2D conductive metal-organic frameworks (cMOFs) have shown great potential in several applications, including sensing, energy storage, and electrocatalysis, due to their bimetallic characteristics. Here, we report a detailed metal substitution study on a family of isostructural cMOFs with Co2+, Ni2+, and Cu2+ as both the metal nodes and the metal centers in the MOAPc ligands. We observed that different metal nodes had variations in the reaction kinetics, particle sizes, and crystallinities. Importantly, the electronic structure and conductivity were found to be dependent on both types of metal sites in the 2D cMOFs. Ni-NiOAPc was found to be the most conductive one among the nine possible combinations with a conductivity of 54 ± 4.8 mS/cm. DFT calculations revealed that monolayer Ni-NiOAPc has neither the smallest bandgap nor the highest charge carrier mobility. Hence its highest conductivity stems from its high crystallinity. Collectively, these results provide structure property relationships for MOAPc-based cMOFs with amino coordination units.

Rheological profile of graphene-based nanofluids in thermal oil with hybrid additives of carbon nanotubes and nanofibers

The evolution in nanofluid technology in the last few decades has proved the prodigious potential in several applications, especially thermal management and lubrication. An extensive investigation of nanofluid's rheological profile is vital to characterize the fluid flow behavior. This study signifies the rheological aspects of graphene and its hybrid nano-dispersions in thermal oil. The experimental investigation involves three sets of nanofluids containing graphene, graphene-carbon nanotubes, and graphene-carbon nanofiber hybrid nanofluid dispersions in thermal oil with varying loadings (0–2 mass%). The flow behaviors of all sets of nanofluids are measured at a wide shear range of 1–2000 s−1 and five different temperatures from 298 K to 338 K. The morphology and stability are validated by performing several characterizations for nanomaterials and nanofluids. Non-Newtonian fluid behavior is observed in all nanofluids. This study reveals a few interesting outcomes where the fluid behaving as a Power Law model is shifted to the Herschel-Bulkley model at high loadings of nanomaterials. A comparative analysis illustrates that both hybrid additives act as viscosity reducers for graphene-based nanofluids, where graphene-carbon nanofibers hybrid nanofluids exhibit noticeable reduction. A parametric analysis is performed on the viscous behavior involving the impact of shear rate, temperature, nanomaterial loading, and surfactant concentration. The increment in viscosity shoots up to 180 % for graphene-nanofluid at the 2000 s−1 shear rate and 338 K temperature, but still exhibits shear thinning phenomena. A correlation is also proposed for the nanofluid viscosity in terms of nanomaterial loading and temperature, indicating a good agreement at varying shear rates.

Progress of auxetic and semi-auxetic materials

Auxetic materials with negative Poisson's ratios, display the unique behavior owing to their micro-structure or geometrical build. Auxetic materials resist deformities when subjected to uniaxial, biaxial, and shearing stresses. Cellular based materials are known for their excellent impact and shock energy absorption. When foams are incorporated with auxetic geometry, their impact energy absorption increases. Combination of auxetic materials with conventional materials yield semi-auxetic materials. Ideally, layered structures where facing materials are metallic sheets sandwiching polymeric foam cores are popular. The auxetic materials can be combined with conventional materials to obtain P-N-P and N-P-N semi-auxetic sandwiched structures with diverse potential in several applications like automotive, aerospace, sports equipment, and protective armors.

New insight into the role of oxygen supply for surfactin production in bench-scale bioreactors using induced surface aeration.

Surfactin biosurfactant produced by Bacillus sp. has been studied, because it has enormous potential in several applications in the oil and cosmetics industry. The cultivation conditions for obtaining this bioproduct, however, still require attention, as, for example, parameters related to oxygen supply and consumption. In this study, different volumetric oxygen transfer coefficient (KLa) levels (0-11.56h-1) were tested in bench-scale bioreactor for surfactin biosurfactant production by Bacillus velezensis H2O-1, using induced surface aeration. While conditions close to anaerobiosis showed insignificant production of surfactin, an intermediated KLa condition (4.24h-1) generated the best surfactin concentration (579.6mg L-1), with a volumetric productivity of 11.9mg L-1h-1. These results showed that the oxygen demand to produce surfactin is not high, being possible to use induced surface aeration strategy in bioreactors, minimizing foam formation. In addition, in all KLa conditions tested, surfactin homologues C14 and C15 had higher relative abundance. Nevertheless, the KLa parameter seems to have had minimal influence on affecting the relative abundances of surfactin homologues produced. Particularly noteworthy in this study is the possibility of producing surfactin using a low-cost and scale-up feasible aeration strategy, unlike the foam collection strategies developed in other studies to obtain this bioproduct.

Quantum Dots and Their Interaction with Biological Systems.

Quantum dots are nanocrystals with bright and tunable fluorescence. Due to their unique property, quantum dots are sought after for their potential in several applications in biomedical sciences as well as industrial use. However, concerns regarding QDs’ toxicity toward the environment and other biological systems have been rising rapidly in the past decade. In this mini-review, we summarize the most up-to-date details regarding quantum dots’ impacts, as well as QDs’ interaction with mammalian organisms, fungal organisms, and plants at the cellular, tissue, and organismal level. We also provide details about QDs’ cellular uptake and trafficking, and QDs’ general interactions with biological structures. In this mini-review, we aim to provide a better understanding of our current standing in the research of quantum dots, point out some knowledge gaps in the field, and provide hints for potential future research.

Fabrication and Characterization of Zwitterionic Coatings with Anti-oil and Anti-biofouling Activities

Underwater ultraoleophobic materials with superhydrophilic surfaces have great potential for several applications due to their anti-fouling, self-cleaning, oil/water separation, droplet manipulation, and drag reduction properties. In our research described here an underwater ultraoleophobic coating containing zwitterion carboxybetaine acrylamide (CBAA) was prepared using self-polymerization of dopamine (DA) and co-deposition of polydopamine (PDA) with zwitterionic poly(carboxybetaine acrylamide) (PCBAA) based on hydroxyl radical activation. The morphology of the coatings could be easily controlled by adjusting the initial ratio of dopamine/carboxybetaine acrylamide (DA/CBAA). The structures, surface morphologies and properties of the coatings so obtained were analyzed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements. The polydopamine/poly(carboxybetaine acrylamide) (PDA/PCBAA) coatings exhibited excellent superhydrophilicity and underwater superoleophobicity with water contact angles (WCA) of 1.5° and underwater oleophobicity contact angles (OCA) of 160°. The anti-biofouling, oil-water separation, and mechanical stability properties for PDA/PCBAA co-deposited coating were comprehensively investigated. These interesting properties make the coatings promising candidates for numerous applications.

Transfer characteristics for laser-induced forward transfer of stainless steel particle

Additive manufacturing (AM) holds great development potential in several applications. In particular, the fabrication of metal parts has been rapidly developing as an industry recently. In such applications, a powder feeder with low material loss is required to ensure effective material usage. Thus, the manufacturing process using laser-induced forward transfer (LIFT) is attractive as a candidate for advances in powder feeder technology. We show that stainless steel particle with diameters of 26 to 53 μm can be transferred via the particle LIFT process; the transfer of particles started at a peak fluence of ∼0.05 J cm − 2 (26- and 36-μm diameters) and ∼0.15 J cm − 2 (53-μm diameter), and the particles were fully transferred (i.e., the probability of transfer reaches unity) at a peak fluence of 0.2 (26 μm), 0.4 (39 μm), and 0.5 J cm − 2 (53 μm). The initial velocity, v0, at which the particle leaves the substrate increased proportionally with the increase in peak fluence. When the point of irradiation of the laser beam was displaced from the contact point of the particle on the substrate, the particle was transferred with a transfer angle (i.e., not vertically). These results demonstrate the possibility of transferring metal particles via the LIFT process. To use this technology for AM, the laser power should be adjusted to control the transfer angle of the particle.

CRITICAL REVIEW OF BIOSURFACTANTS AND THEIR ROLE IN BIOREMEDIATION OF PETROLEUM HYDROCARBON CONTAMINANTS.

Biotechnological advances for the past decades have provided new surfactant production technologies. Surface active substances (biosurfactants) produced by fermentative processes have proven to be a safer and sustainable alternative to many synthetic molecules. Biosurfactants are a promising substitute due to their synthesis potential by a wide variety of microorganisms. They are a highly diverse group of structures, such as glycolipids, lipopeptides, polysaccharide-protein complexes, phospholipids, fatty acids, and neutral lipids. This diversity promotes many advantages compared to synthetic surfactants, thereby making biosurfactants a suitable choice for technological advances associated with sustainable development. Such advantages include fermentative production viability using renewable resources, effectiveness in small concentrations even under extreme conditions, selective and specific potential for several applications, lower toxicity, higher biodegradability, and better stability to physicochemical variations. Despite these benefits enumerated, they are not widely used because of the high production costs. Hence, finding cost-effective substrates is imperative to making biosurfactants an economically competitive product against synthetic surfactants. In this review, inexpensive and renewable substrates that can be used for biosurfactants production are discussed. Also, biosurfactants and their potential use in bioremediation of hydrocarbon contaminants, and effectiveness in bioremediation of hydrocarbon contaminants compared to synthetic surfactants are reviewed. Keywords: Biosurfactants, Hydrocarbon degradation, Bioremediation, Environment.

Development of a continuum robot enhanced with distributed sensors for search and rescue

Continuum robots can enter narrow spaces and are useful for search and rescue missions in disaster sites. The exploration efficiency at disaster sites improves if the robots can simultaneously acquire several pieces of information. However, a continuum robot that can simultaneously acquire information to such an extent has not yet been designed. This is because attaching multiple sensors to the robot without compromising its body flexibility is challenging. In this study, we installed multiple small sensors in a distributed manner to develop a continuum-robot system with multiple information-gathering functions. In addition, a field experiment with the robot demonstrated that the gathered multiple information has a potential to improve the searching efficiency. Concretely, we developed an active scope camera with sensory functions, which was equipped with a total of 80 distributed sensors, such as inertial measurement units, microphones, speakers, and vibration sensors. Herein, we consider space-saving, noise reduction, and the ease of maintenance for designing the robot. The developed robot can communicate with all the attached sensors even if it is bent with a minimum bending radius of 250 mm. We also developed an operation interface that integrates search-support technologies using the information gathered via sensors. We demonstrated the survivor search procedure in a simulated rubble environment of the Fukushima Robot Test Field. We confirmed that the information provided through the operation interface is useful for searching and finding survivors. The limitations of the designed system are also discussed. The development of such a continuum robot system, with a great potential for several applications, extends the application of continuum robots to disaster management and will benefit the community at large.

Design of a bi-layer coating configuration on ultra-high molecular weight polyethylene (UHMWPE) fibre surface to derive synergistic response on interfacial bond strength

In this study, we demonstrate a design of a stable bi-layer coating configuration on UHMWPE fibres surface. UHMWPE fibres show abundant promise as load bearing reinforcement in fibre-based composites; however, its inert chemical nature has been a consistent hurdle for developing high performance composites. An efficient and environmentally friendly two-step coating technique has been performed on UHMWPE fibre surface; viz. Physisorption of polydopamine (PDA) followed by the construction of Polyamide 6,6 coating over PDA layer. The coated fibres revealed improved tensile strength in comparison to the pure UHMWPE fibres. Transverse fibre bundle tension (TFBT) test was used to assess the interfacial bonding strength of the coated fibre with an epoxy matrix. The bi-layer coated fibre/epoxy demonstrated an improvement of ∼ 40% in bonding strength compared to the pure UHMWPE/epoxy system. This bi-layer coated UHMWPE fibres could be of immense potential for several applications, including biomedical engineering.

Exploring the Stability of Direct Ethanol Solid Oxide Fuel Cells at Intermediate Temperature

Direct ethanol SOFC have gained increasing attention in the last decade due to a series of attractive characteristic of such renewable fuel. Ethanol is possibly the most successful example of biofuel with well-developed industries in different continents. Countries with large production, such as Brazil and USA, have a wide distribution infrastructure that makes ethanol a readily available fuel. Ethanol SOFC has a great potential for several applications, including as a range extender for electric vehicles as recently demonstrated by Nissan. Nevertheless, to reduce the complexity and cost of fuel cell systems, several studies have aimed at internal reforming taking advantage of the SOFC operating temperature. Nonetheless, critical issues such as the stability of the anodes and thermal stress arising from the endothermic reforming reactions still impose great challenge for the internal reforming in SOFC. Previous studies have demonstrated direct ethanol SOFCs operating with great stability for more than 600 hours at 850 °C [1]. On the other hand, relatively few studies have investigated direct ethanol SOFCs at T< 800 °C. Intermediate operating temperatures facilitate material selection, inhibit thermally activated degradation processes, and allow a fast start of the system. However, critical issues such as the stability of the anode require careful development for stable operation at intermediate temperature (600 - 700 °C). Usually, ethanol steam reforming in this temperature range demands specific catalysts to avoid the formation of carbon deposits. Therefore, it is necessary to develop stable catalysts that are resistant to carbon formation at intermediate temperature to facilitate the commercialization of the direct ethanol SOFC technology. The aim of this study is to evaluate catalytic materials in the active layer deposited in commercial anode-supported SOFC at intermediate temperature (600 - 700 °C). Steam reforming reactions were combined with electrochemical single cell testing with different active layers containing ceria-based catalysts. The starting point was to evaluate the commercial fuel cells without an active layer under ethanol at intermediate temperature. The as-received fuel cell has reasonable stability under dry ethanol if enough water is produced by the electrochemical polarization of the fuel cell, as shown in Fig. 1. However, the Ni-based anode develops carbon deposits under operation on dry ethanol. The Ir/doped-ceria catalyst previously studied at 850 °C showing excellent durability was investigated at reduced temperature. The steam reforming results revealed that the studied catalyst deactivate at 600 °C. Increasing the measuring temperature to 700 °C revealed that the catalyst remains active, but displays small carbon deposits after the catalytic reaction, as inferred by Raman spectroscopy and thermal gravimetry analyses. The main results have shown that the catalytic layer has no significant effect on the performance of the fuel cell under hydrogen, as long the microstructural properties of the catalytic layer, such as porosity and good adhesion to the anode, are ensured. The use of a ceria-based catalytic layer has enhanced the stability of the fuel cell under dry ethanol, but small carbon deposits were still detected after ~150 hours of continuous operation.[1] Steil, M.C.; Nobrega, S.D.; Georges, S.; Gelin, P.; Uhlenbruck, S.; Fonseca, F.C. Durable direct ethanol anode-supported solid oxide fuel cell. Applied Energy, 199, 2017, p. 180-186. Figure 1

Transition between toroidic orders in dielectric metasurfaces by polarization of the incident wave.

We propose a design and perform a theoretical and experimental study of optical properties of a metasurface composed of hexagonal oligomers of dielectric particles that somewhat resemble characteristics of multiferroics. It can maintain both toroidic and antitoroidic orders in the dynamical response on irradiation by a linearly polarized plane wave. These orders originate from the dark states of toroidal dipole moments. Due to the consciously chosen perturbation in the oligomers, the orders are excited at the same frequency by the wave with orthogonal polarization. The excitation of these orders results in different characteristics of the electric near-field localization. This has significant potential for several applications, which are thoroughly discussed.

Sustainable Surfactin Production by Bacillus subtilis Using Crude Glycerol from Different Wastes.

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography–mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.

Quantifying the Plasmonic Generation Rate of Non‐Thermal Hot Carriers with an AlGaN/GaN High‐Electron‐Mobility Transistor

AbstractPlasmonic generation of hot carriers in metallic nanostructures has attracted much attention due to its great potential in several applications. However, it is highly debated whether the enhancement is due to the hot carriers or the thermal effect. Here, the ability to exclude the thermal effect and detect the generation of non‐thermal hot carriers by surface plasmon is demonstrated using an AlGaN/GaN high‐electron‐mobility transistor. This ultrasensitive platform, which demonstrates at least two orders of magnitude more sensitivity compared to the previous reports, can detect the hot carriers generated from discrete nanostructures illuminated by a continuous wave light. The quantitative measurements of hot carrier generation also open a new way to optimize the plasmonic nanoantenna design in many applications.

Sunflower seed byproduct and its fractions for food application: An attempt to improve the sustainability of the oil process.

The sunflower (Helianthus annus L.) is one of the main oil crops in the world grown for the production of edible and biodiesel oil. Byproducts of the extraction of sunflower oil constitute a raw material with potential for several applications in the food area due to its chemical composition, including the high content of proteins and phenolic compounds. Thoughtful of a consumer increasingly concerned with the environmental impact, we try to clarify in this review the potential of using sunflower seed byproducts and their fractions to enhance the production of potentially functional foods. The applications of sunflower seed byproduct include its transformation into flours/ingredients that are capable of improving the nutritional and functional value of foods. In addition, the protein isolates obtained from sunflower seed byproduct have good technological properties and improve the nutritional value of food products. These protein isolates can be used to obtain protein hydrolysates with technological and bioactive properties and as matrices for the development of edible, biodegradable, and active films for food. The sunflower seed byproduct is also a source of phenolic compounds with bioactive properties, mainly chlorogenic acid, which can be extracted by different methods and applied in the development of functional foods and active and bioactive food packaging. The use of sunflower seed byproduct and its fractions are promising ingredients for the development of healthier and less expensive foods as well as the alternative to decrease the environmental problems caused by the sunflower oil industry.

A theorized new class of polyhedral hydrocarbons of molecular formula CnHn and their bottom-up scaffold expansions into hyperstructures

We address the use of Euler's theorem and topological algorithms to design 18 polyhedral hydrocarbons of general formula CnHn that exist up to 28 vertexes containing four- and six-membered rings only; compounds we call “nuggets”. Subsequently, we evaluated their energies to verify the likelihood of their chemical existence. Among these compounds, 13 are novel systems, of which 3 exhibit chirality. Further, the ability of all nuggets to perform fusion reactions either through their square faces, or through their hexagonal faces was evaluated. Indeed, they are potentially able to form bottom-up derived molecular hyperstructures with great potential for several applications. By considering these fusion abilities, the growth of the nuggets into 1D, 2D, and 3D-scaffolds was studied. The results indicate that nugget24a (C24H24) is predicted to be capable of carrying out fusion reactions. From nugget24a, we then designed 1D, 2D, and 3D-scaffolds that are predicted to be formed by favorable fusion reactions. Finally, a 3D-scaffold generated from nugget24a exhibited potential to be employed as a voxel with a chemical structure remarkably similar to that of MOF ZIF-8. And, such a voxel, could in principle be employed to generate any 3D sculpture with nugget24a as its level of finest granularity.

Tuning the Magnetic Properties of Two-Dimensional MXenes by Chemical Etching.

Two-dimensional materials based on transition metal carbides have been intensively studied due to their unique properties including metallic conductivity, hydrophilicity and structural diversity and have shown a great potential in several applications, for example, energy storage, sensing and optoelectronics. While MXenes based on magnetic transition elements show interesting magnetic properties, not much is known about the magnetic properties of titanium-based MXenes. Here, we measured the magnetic properties of Ti3C2Tx MXenes synthesized by different chemical etching conditions such as etching temperature and time. Our magnetic measurements were performed in a superconducting quantum interference device (SQUID) vibrating sample. These data suggest that there is a paramagnetic-antiferromagnetic (PM-AFM) phase transition and the transition temperature depends on the synthesis procedure of MXenes. Our observation indicates that the magnetic properties of these MXenes can be tuned by the extent of chemical etching, which can be beneficial for the design of MXenes-based spintronic devices.