Materials Science and Engineering

Florida City, FL, United States

Materials Science and Engineering

Florida City, FL, United States
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Ozutok F.,Science Faculty | Demiri S.,Materials Science and Engineering | Ozbek E.,Materials Science and Engineering
AIP Conference Proceedings | Year: 2017

Recently, smart windows are very important because they are often being used in smart buildings and car glasses (windows). At this point, producing effective electrochromic materials is so necessary. In this study, we produced NiO thin films by using spin coating technique on In-doped SnO2 (ITO) substrate. Nickel proportions of these nickel oxide (NiO) films are 3, 5 and 7 %. Nickel acetate tetrahydrate is the initial solution and solvents are ethylene gl ycol and n-hexzane. Structural properties and surface images are investigated by using x-ray diffactometer (XRD) and scanning electron microscope (SEM) device, respectively. In addition, electrochemical behavior is investigated by cyclic voltammetry. A correlation between surface morphology and electrochromic performance was observed as well. © 2017 Author(s).

Dados A.,Cp Foodlab | Paparizou E.,Cp Foodlab | Paparizou E.,University of Ioannina | Eleftheriou P.,Materials Science and Engineering | And 2 more authors.
Talanta | Year: 2014

A slurry suspension sampling technique is developed and optimized for the rapid microextraction of heavy metals and analysis using nanometer-sized ceria-coated silica-iron oxide particles and inductively coupled plasma optical emission spectrometry (ICP-OES). Magnetic-silica material is synthesized by a co-precipitation and sol-gel method followed by ceria coating through a precipitation. The large particles are removed using a sedimentation- fractionation procedure and a magnetic homogeneous colloidal suspension of ceria-modified iron oxide-silica is produced for microextraction. The nanometer-sized particles are separated from the sample solution magnetically and analyzed with ICP-OES using a slurry suspension sampling approach. The ceria-modified iron oxide-silica does not contain any organic matter and this probably justifies the absence of matrix effect on plasma atomization capacity, when increased concentrations of slurries are aspirated. The As, Be, Mo, Cr, Cu, Pb, Hg, Sb, Se and V can be preconcentrated by the proposed method at pH 6.0 while Mn, Cd, Co and Ni require a pH≥8.0. Satisfactory values are obtained for the relative standard deviations (2-6%), recoveries (88-102%), enrichment factors (14-19) and regression correlation coefficients as well as detectability, at sub-μg L-1 levels. The applicability of magnetic ceria for the microextraction of metal ions in combination with the slurry introduction technique using ICP is substantiated by the analysis of environmental water and urine samples. © 2013 Elsevier B.V.

Cossu F.,Materials Science and Engineering | Schwingenschlogl U.,Materials Science and Engineering | Colizzi G.,CNR Institute of Materials | Filippetti A.,CNR Institute of Materials | Fiorentini V.,CNR Institute of Materials
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Using first-principles calculations, we show that the (001) surface of the ferromagnet La0.7Sr0.3MnO3 under an epitaxial compressive strain favors antiferromagnetic (AF) order in the surface layers, coexisting with ferromagnetic (FM) bulk order. Surface antiferromagnetism is accompanied by a very marked surface-related spectral pseudogap, signaling an incomplete metal-insulator transition at the surface. The different relaxation and rumpling of the MnO2 and LaO surface planes in the two competing magnetic phases cause distinct work-function changes, which are of potential diagnostic use. The AF phase is recognized as an extreme surface-assisted case of the combination of in-plane AF super-exchange and vertical FM double-exchange couplings that rules magnetism in manganites under in-plane compression. © 2013 American Physical Society.

Bhaskar S.,University of Michigan | Pollock K.M.,Cornell University | Yoshida M.,University of Michigan | Lahann J.,Materials Science and Engineering
Small | Year: 2010

Biodegradable, compositionally anisotropic micro particles with two distinct compartments that exhibit controlled shapes and sizes are fabricated. These multifunctional particles are prepared by electrohydrodynamic cojetting of poly(lactide-co-glycolide) polymer solutions. By varying different solution and process parameters, namely, concentration and flow rate, a variety of non-equilibrium bicompartmental shapes, such as discoid and rod-shaped microparticles are produced in high yields. Optimization of jetting parameters, combined with filtration, results in near-perfect, bicompartmental spherical particles in the size range of 3-5 μm. Simultaneous control over anisotropy, size, shape and surface structure provides an opportunity to create truly multifunctional microparticles for a variety of biological applications, such as drug delivery, diagnostic assays and theranostics. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Manchon A.,Materials Science and Engineering | Manchon A.,University of Arizona | Zhang S.,University of Arizona | Lee K.-J.,Korea University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The influence of structural asymmetries (barrier height and exchange splitting), as well as inelastic scattering (magnons and phonons) on the bias dependence of the spin transfer torque in a magnetic tunnel junction is studied theoretically using the free-electron model. We show that they modify the "conventional" bias dependence of the spin transfer torque, together with the bias dependence of the conductance. In particular, both structural asymmetries and bulk (inelastic) scattering add antisymmetric terms to the perpendicular torque (V and je |V|) while the interfacial inelastic scattering conserves the junction symmetry and only produces symmetric terms ( ⊃|V⊃| n, nN). The analysis of spin torque and conductance measurements displays a signature revealing the origin (asymmetry or inelastic scattering) of the discrepancy. © 2010 The American Physical Society.

Goker A.,Bilecik University | Zhu Z.Y.,Materials Science and Engineering | Manchon A.,Materials Science and Engineering | Schwingenschlogl U.,Materials Science and Engineering
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We invoke the time-dependent noncrossing approximation in order to study the effects of the density of states of gold contacts on the instantaneous conductance of a single electron transistor which is abruptly moved into the Kondo regime by means of a gate voltage. For an asymmetrically coupled system, we observe that the instantaneous conductance in the Kondo time scale exhibits beating with distinct frequencies, which are proportional to the separation between the Fermi level and the sharp features in the density of states of gold. Increasing the ambient temperature or bias quenches the amplitude of the oscillations. We attribute the oscillations to interference between the emerging Kondo resonance and van-Hove singularities in the density of state. In addition, we propose an experimental realization of this model. © 2010 The American Physical Society.

Wang C.,Materials Science and Engineering | Wang Y.,Materials Science and Engineering | Graser J.,Materials Science and Engineering | Zhao R.,Arizona State University | And 2 more authors.
ACS Nano | Year: 2013

A facile and scalable solution-based, spray pyrolysis synthesis technique was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m2/g using a novel metal-salt catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. These hollow carbon nanospheres showed adsorption of to 300 mg of dye per gram of carbon, which is more than 15 times higher than that observed for conventional carbon black particles. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed, with no capacitance loss after 20 000 cycles. © 2013 American Chemical Society.

Acerce M.,Materials Science and Engineering | Voiry D.,Materials Science and Engineering | Chhowalla M.,Materials Science and Engineering
Nature Nanotechnology | Year: 2015

Efficient intercalation of ions in layered materials forms the basis of electrochemical energy storage devices such as batteries and capacitors. Recent research has focused on the exfoliation of layered materials and then restacking the two-dimensional exfoliated nanosheets to form electrodes with enhanced electrochemical response. Here, we show that chemically exfoliated nanosheets of MoS2 containing a high concentration of the metallic 1T phase can electrochemically intercalate ions such as H+, Li+, Na+ and K+ with extraordinary efficiency and achieve capacitance values ranging from ∼400 to ∼700 F cm-3 in a variety of aqueous electrolytes. We also demonstrate that this material is suitable for high-voltage (3.5 V) operation in non-aqueous organic electrolytes, showing prime volumetric energy and power density values, coulombic efficiencies in excess of 95%, and stability over 5,000 cycles. As we show by X-ray diffraction analysis, these favourable electrochemical properties of 1T MoS2 layers are mainly a result of their hydrophilicity and high electrical conductivity, as well as the ability of the exfoliated layers to dynamically expand and intercalate the various ions. © 2015 Macmillan Publishers Limited. All rights reserved.

Petrie J.R.,CSIRO | Shrestha P.,CSIRO | Belide S.,CSIRO | Kennedy Y.,CSIRO | And 7 more authors.
PLoS ONE | Year: 2014

Background: Omega-3 long-chain (≥C20) polyunsaturated fatty acids (ω3 LC-PUFA) such as eicosapentaenoic acid (EPA) and docosapentaenoic acid (DHA) are critical for human health and development. Numerous studies have indicated that deficiencies in these fatty acids can increase the risk or severity of cardiovascular, inflammatory and other diseases or disorders. EPA and DHA are predominantly sourced from marine fish although the primary producers are microalgae. Much work has been done to engineer a sustainable land-based source of EPA and DHA to reduce pressure on fish stocks in meeting future demand, with previous studies describing the production of fish oil-like levels of DHA in the model plant species, Arabidopsis thaliana. Principal Findings: In this study we describe the production of fish oil-like levels (>12%) of DHA in the oilseed crop species Camelina sativa achieving a high ω3/ω6 ratio. The construct previously transformed in Arabidopsis as well as two modified construct versions designed to increase DHA production were used. DHA was found to be stable to at least the T5 generation and the EPA and DHA were found to be predominantly at the sn-1,3 positions of triacylglycerols. Transgenic and parental lines did not have different germination or seedling establishment rates. Conclusions: DHA can be produced at fish oil-like levels in industrially-relevant oilseed crop species using multi-gene construct designs which are stable over multiple generations. This study has implications for the future of sustainable EPA and DHA production from land-based sources. © 2014 Petrie et al.

Manchon A.,Materials Science and Engineering
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Spin transport in magnetic tunnel junctions comprising a single magnetic layer in the presence of interfacial spin-orbit interaction (SOI) is investigated theoretically. Due to the presence of interfacial SOI, a current-driven spin torque can be generated at the second order in SOI, even in the absence of an external spin polarizer. This torque possesses two components, one in plane and one perpendicular to the plane of rotation, that can induce either current-driven magnetization switching from an in-plane to out-of-plane configuration or magnetization precessions, similar to spin transfer torque in spin valves. Consequently, it appears that it is possible to control the magnetization steady state and dynamics by either varying the bias voltage or electrically modifying the SOI at the interface. © 2011 American Physical Society.

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