Yanbo Wang
Nanowires (NWs) are of structures with diameters usually constrained to the range of nanometres and unconstrained lengths, resulting in quantum mechanical effects in two dimensions. NWs have significant applications as nanoscale interconnects and active components of electronic, optoelectronic nano-devices. While the synthesis/growth and the physical properties of NWs have been extensively investigated, the mechanical properties, especially the effects of nano-size dimensions on the mechanical properties have been largely overlooked up to now due to the difficulty of the mechanical characterization of nanoscale objects. However, understanding the mechanical behavior of NWs as a function of NW diameter is extremely important, especially in semiconductor NWs, because the reliability and even functionality of NW-based devices can depend on the mechanical properties of the NWs. The present work is to apply state-of-the-art in-situ deformation transmission electron microscopy techniques to explore outstanding issues on the mechanical behavior of GaAs semiconductor NWs. Results show that the mechanical behavior of GaAs NWs changes with diameters from several hundred nanometers to several nanometers. The elastic strain of GaAs NWs can be ~11%, which is 100 times higher than that of its bulk form, that obvious plastic deformation occurs via partial dislocation motion in diameter of 25nm, while bulk GaAs semiconductor is generally brittle at room temperature. With diameter decreasing, a recoverable deformation, a repeatable self-healing process occurred when an external compressive force was removed.
Alireza Karimaghaloo and Min Hwan Lee
Oxygen reduction reaction (ORR) is a sluggish process that causes significant voltage losses for the cathode in low- and intermediate-temperature solid oxide fuel cells (SOFCs). Surface engineering of electrolytes with nanostructures and thin-film interfaces introduced between the cathode and electrolyte can mitigate the voltage losses associated with ORR on the cathode. In this article, we reveal the actual role of the metal oxide interlayer between electrode-electrolyte in the ORR process through a series of electrochemical analysis and surface imaging techniques. We deposited nanocrystalline yttria-doped ceria (YDC) thin film interface layer on yttria-stabilized zirconia (YSZ) electrolyte by spin coating, atomic layer deposition (ALD) and the combination of these two techniques. These tests have been done on a Pt cathode as a pure electron conductor material and lanthanum strontium cobalt ferrite (LSCF) as a mixed electron and ion conductor (MIEC). The interface layer reduced cell polarization resistance substantially. The reduction in the polarization resistance is primarily attributed to the increased interfacial surface area between the cathode and the electrolyte. Moreover, this procedure enhances the adherence of the porous cathode layer to the electrolyte and decreases the electrode-electrolyte interfacial resistance, as confirmed by scanning electron microscopy (SEM). A remarkable change in oxygen partial pressure dependency is also observed indicating a possible change in the oxygen transfer mechanism. In addition, the test demonstrated the benefits of nanofilm interfacial layer in improving the power output of the cell.
David Moweme Unuigbe
The presence of native oxide on the surface of silicon nanoparticles is renowned for constraining charge transport on the surfaces. Studies carried out using scanning electron microscopy (SEM) shows that the particles in the printed silicon network have a wide range of shapes and sizes. High-resolution transmission electron microscopy reveals that the particle surfaces are dominated by the (111)- and (100)-oriented planes which stabilize against further oxidation of the particles. X-ray absorption spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) measurements at the O 1s-edge have been utilized to study the oxidation and local atomic structure of printed layers of silicon nanoparticles which were milled for different times. XANES results reveal the presence of the +4 (SiO2) oxidation state which tends towards the +2 (SiO) state for higher milling times. Si 2p XPS results indicate that the surfaces of the silicon nanoparticles in the printed layers are only partially oxidized and that all three sub-oxide, +1 (Si2O), +2 (SiO) and +3 (Si2O3), states are present. The analysis of the change in the sub-oxide peaks of the silicon nanoparticles shows the dominance of the +4 state only for lower milling times.
David Patino Ruiz
In the previous couple of years, nanotechnology has been the main target of the many investigations thanks to their nanoscale typical properties with a good range of applications within the electrical, biomedical, biological, chemical and pharmaceutical fields. it's found that iron oxide nanoparticles have an excellent interest due to its important role in technological application and, especially has established a promising within the biological and biomedical fields. These nanoparticles have unique physicochemical properties and capabilities allowing the cellular and molecular interactions within the living organisms and ecosystems, and during this context, some studies could also be considered regarding the evaluation of toxic effects which will be led with the utilization of iron oxide nanoparticles. Taking under consideration the present and wide applications of those nanoparticles, methodologies of synthesis like co-precipitation, thermal decomposition, hydrothermal, among others, have developed concerns about the impacts produced to the environment and therefore the high consumption of energy, reactants, and other resources. Therefore, a green synthesis for nanomaterials preparation has emerged so as to get an equivalent products with an eco-friendly and safe process route, during which natural resources and wastes are used for this purpose. Herein, we present a green chemistry approach for iron oxides nanoparticles synthesis using Cymbopogon aqueous extract as a reducer . The synthesized nanoparticles were characterized using XPS, TEM, VSM, IR, TGA and XRD analysis. Besides, the iron oxide nanoparticles properties were evaluated through antibacterial and eco-toxicity tests, using E. coli and C. elegans respectively.
Iron-based nanoparticles (FeNPs) are used successfully in water treatment and environmental cleanup efforts. This study examined ecotoxicity of two FeNPs produced with extract from tea (smGT, GTFe) and their ability to degrade malachite green (MG). Their physicochemical properties were assessed by transmission microscopy , X-ray powder diffraction, dynamic light scattering, and transmission Mössbauer spectroscopy. employing a battery of ecotoxicological bioassays, we determined the toxicity for nine different organisms, including bacteria, cyanobacteria, algae, plants, and crustaceans. Iron and iron oxide nanoparticles synthesized with tea extract displayed low capacity to degrade MG and were toxic to all or any tested organisms.
Hind AA Al Zahrani
Silver nanoparticles (AgNPs) are widely spread worldwide for several centuries and are extremely utilized in industry, cosmetics, food packaging for its proposed antimicrobial activities. Many reports mentioned the good value of AgNPs in many faces. This review focused on antimicrobial activities of AgNPs, subjecting briefly to their synthesis, with a special specialise in different mechanisms of action and factors affecting these activities as an antimicrobial agent.
Nanotechnology has recently emerged as a rapidly growing field with numerous life science applications. At an equivalent time, silver has been adopted as an antimicrobial material and disinfectant that's relatively freed from adverse effects. Silver nanoparticles possess a broad spectrum of antibacterial, antifungal and antiviral properties. Silver nanoparticles have the power to penetrate bacterial cell walls, changing the structure of cell membranes and even leading to necrobiosis . Their efficacy is due not only to their nanoscale size but also to their large ratio of area to volume. they will increase the permeability of cell membranes, produce reactive oxygen species, and interrupt replication of desoxyribonucleic acid by releasing silver ions. Researchers have studied silver nanoparticles as antimicrobial agents in dentistry. as an example , silver nanoparticles are often incorporated into acrylic resins for fabrication of removable dentures in prosthetic treatment, composite resin in restorative treatment, irrigating solution and obturation material in endodontic treatment, adhesive materials in treatment , membrane for guided tissue regeneration in periodontal treatment, and titanium coating in implant treatment. Although not all authorities have acknowledged the security of silver nanoparticles, no systemic toxicity of ingested silver nanoparticles has been reported. A broad concern is their potential hazard if they're released into the environment. However, the interaction of nanoparticles with toxic materials and organic compounds can either increase or reduce their toxicity. This paper provides an summary of the antibacterial use of silver nanoparticles in dentistry, highlighting their antibacterial mechanism, potential applications and safety in clinical treatment.
Nanotechnology is defined because the design, characterization and application of structures, devices and systems by controlling shape and size at a nanometer scale (1 nm to 100 nm). it's an emerging field of research, with various applications in science and technology, particularly for developing new materials. Nanoparticles are developed with unique properties that make them desirable in materials science and biology. Among various nanoparticles, silver nanoparticles are one among the foremost popular objects of study in recent decades. Silver nanoparticles contain 20 to fifteen ,000 silver atoms, and their diameters are usually smaller than 100 nm. thanks to an outsized surface-to-volume ratio, silver nanoparticles exhibit remarkable antimicrobial activity, even at a coffee concentration. additionally , they're low cost and have shown low cytotoxicity and immunological response. Therefore, silver nanoparticles have multiple potential biomedical applications. they're used for drug delivery, medical imaging and molecular diagnostics. they're also utilized in therapeutics, like surgical mesh, fabrication of implant replacements, wound dressing and medicament for the promotion of wound healing.
Journal of Nanosciences: Current Research received 387 citations as per Google Scholar report
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