Nanobelt formation of magnesium hydroxide sulfate hydrate via a soft chemistry process.

PubMed

Zhou, Zhengzhi; Sun, Qunhui; Hu, Zeshan; Deng, Yulin

2006-07-13

The nanobelt formation of magnesium hydroxide sulfate hydrate (MHSH) via a soft chemistry approach using carbonate salt and magnesium sulfate as reactants was successfully demonstrated. X-ray diffraction (XRD), energy dispersion X-ray spectra (EDS), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis revealed that the MHSH nanobelts possessed a thin belt structure (approximately 50 nm in thickness) and a rectangular cross profile (approximately 200 nm in width). The MHSH nanobelts suffered decomposition under electron beam irradiation during TEM observation and formed MgO with the pristine nanobelt morphology preserved. The formation process of the MHSH nanobelts was studied by tracking the morphology of the MHSH nanobelts during the reaction. A possible chemical reaction mechanism is proposed.

Electron backscatter diffraction applied to lithium sheets prepared by broad ion beam milling.

PubMed

Brodusch, Nicolas; Zaghib, Karim; Gauvin, Raynald

2015-01-01

Due to its very low hardness and atomic number, pure lithium cannot be prepared by conventional methods prior to scanning electron microscopy analysis. Here, we report on the characterization of pure lithium metallic sheets used as base electrodes in the lithium-ion battery technology using electron backscatter diffraction (EBSD) and X-ray microanalysis using energy dispersive spectroscopy (EDS) after the sheet surface was polished by broad argon ion milling (IM). No grinding and polishing were necessary to achieve the sufficiently damage free necessary for surface analysis. Based on EDS results the impurities could be characterized and EBSD revealed the microsctructure and microtexture of this material with accuracy. The beam damage and oxidation/hydration resulting from the intensive use of IM and the transfer of the sample into the microscope chamber was estimated to be <50 nm. Despite the fact that the IM process generates an increase of temperature at the specimen surface, it was assumed that the milling parameters were sufficient to minimize the heating effect on the surface temperature. However, a cryo-stage should be used if available during milling to guaranty a heating artefact free surface after the milling process. © 2014 Wiley Periodicals, Inc.

Characterisation and sintering of nanophase hydroxyapatite synthesised by a species of Serratia

NASA Astrophysics Data System (ADS)

LSammons, R.; Thackray, A. C.; Medina Ledo, H.; Marquis, P. M.; Jones, I. P.; Yong, P.; Macaskie, L. E.

2007-12-01

The bacterium Serratia sp. NCIMB40259, which grows as a biofilm on polymeric, glass and metal substrates, produces extracellular crystals of hydroxyapatite (HA) by enzymatic cleavage of β-glycerophosphate in the presence of calcium chloride. Following growth on polyurethane foam, biomineralisation and subsequent sintering, an HA scaffold is formed whose three-dimensional architecture replicates that of the foam and the biofilm. Serratia HA was characterised using X-ray diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR), energy dispersive X-ray analysis (EDX) scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). The nascent, unsintered material consisted mainly of calcium-deficient HA (CDHA) with a Ca/P ratio of 1.61+/- 0.06 and crystal size (TEM) of 50 +/- 10nm length. ED of unsintered crystals and crystals sintered at 600° C showed resolvable ring (unsintered) or dot (600° C) patterns ascribed to (0002), (1122) and (0006) planes of crystalline HA. Material sintered at 1200° C consisted of needle-like crystals of length range 54-111nm (XRD) with lattice parameters of a = 9.441 Å and c = 6.875 Å, consistent with HA.

Structure and conformation of 1,4-difluorobutane as determined by gas-phase electron diffraction, and by molecular mechanics and ab initio calculations

NASA Astrophysics Data System (ADS)

Krosley, Kevin; Hagen, Kolbjørn; Hedberg, Kenneth

1995-06-01

Gas-phase electron diffraction data at 23°C together with molecular mechanics (MM3) and ab initio (HF/6-31G∗, gaussian 86) calculations have been used to determine the structure and conformations of 1,4-difluorobutane. The object was to ascertain whether effects similar to the gauche effect in 1,2-difluoroethane, which serves to stabilize the gauche form with the fluorine atoms in close proximity, could also operate in 1,4-difluorobutane. It was found both theoretically and experimentally that the proportion of those conformers having close fluorine atoms was small, implying the absence of effects similar to the gauche effect. The conformational composition estimated from the theoretical calculations is in good agreement with the experimental data. The experimental electron diffraction results constrained by assumptions drawn from the theoretical calculations, ED/MM3 [ED/ab initio], for the principal distances ( {r g}/{Å}) and angles ( {∠ α}/{deg}) with estimated 2σ uncertainties are as follows: r(CH) = 1.105(3) [1.106(3)], r(CF) = 1.398(2) [1.398(2)], r(C 1C 2) = 1.513(2) [1.516(2)], r(C 2C 3) = 1.537(2) [1.532(2)], ∠FCC = 110.9(3) [111.1(3)], ∠CCC = 112.9(4) [112.9(4)], and ∠HCH = 100(3) [100(3)].

Theoretical determination of molecular structure and conformation. Part X. Geometry and puckering potential of azetidine, (CH 2) 3NH, combination of electron diffraction and ab initio studies

NASA Astrophysics Data System (ADS)

Cremer, Dieter; Dorofeeva, Olga V.; Mastryukov, Vladimir S.

1981-09-01

Restricted Hartree—Fock calculations on 21 planar and puckered conformers of azetidine have been done employing a split valence basis augmented by d functions. Complete geometry optimizations have been performed for eight conformers. In this way the puckering potential of azetidine is explored over the range -40° < ø (puckering angle) < 40°, for both sp3 and sp2 hybridization of the nitrogen atom. In its equatorial form, azetidine is slightly more puckered than cyclobutane. This is because of a decrease of van der Waals' repulsion between H atoms. Charge effects lead to destabilization of the axial forms. There is only moderate coupling between puckering and methylene group rocking. Previously published electron diffraction (ED) data are reinvestigated using vibrational corrections and information from the ab initio calculations. On the basis of this MO constrained ED (MOCED) analysis a puckering angle φ = 35.1(1.8)° is found. Observed rg and re bond distances are compared with ab initio values.

Structural and Spectral Characterization of Co2+- and Ni2+-DOPED CdO Powder Prepared From Solution at Room Temperature

NASA Astrophysics Data System (ADS)

Reddy, C. V.; Rao, L. V. Krishna; Satish, D. V.; Shim, J.; Ravikumar, R. V. S. S. N.

2015-11-01

The mild and simple solution method was used for the synthesis of Co2+- and Ni2+-doped CdO powders at room temperature. The prepared powders were characterized using powder X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), optical absorption, and Fourier transform infrared spectroscopy (FTIR). From the powder X-ray diffraction patterns, it has been observed that the prepared Co2+ and Ni2+ ion-doped CdO powders belong to the cubic phase, and the evaluated average crystalline sizes of the powders are 20 and 14 nm, respectively. The SEM images and the EDS spectra show that the prepared powders are distributed over different sizes in the grain boundaries. Optical absorption studies allow determination of site symmetry of the metal ion with its ligands. The crystal field (Dq) and inter-electronic repulsion (B and C) parameters have been evaluated from the optical absorption spectra. The FTIR spectra show the characteristic fundamental vibrations of the metal oxide and CdO.

Photosynthetic microorganism-mediated synthesis of akaganeite (beta-FeOOH) nanorods.

PubMed

Brayner, Roberta; Yéprémian, Claude; Djediat, Chakib; Coradin, Thibaud; Herbst, Fréderic; Livage, Jacques; Fiévet, Fernand; Couté, Alain

2009-09-01

Common Anabaena and Calothrix cyanobacteria and Klebsormidium green algae are shown to form intracellularly akaganeite beta-FeOOH nanorods of well-controlled size and unusual morphology at room temperature. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy X-ray energy dispersive spectrometry (SEM-EDS) analyses are used to investigate particle structure, size, and morphology. A mechanism involving iron-siderophore complex formation is proposed and compared with iron biomineralization in magnetotactic bacteria.

Analysis of pigments from Roman wall paintings found in the "agro centuriato" of Julia Concordia (Italy).

PubMed

Mazzocchin, Gian-Antonio; Del Favero, Michela; Tasca, Giovanni

2007-09-01

The analysis of wall painting fragments recovered in the "agro centuriato" of Julia Concordia has been carried out by using Scanning Electron Microscopy equipped with an EDS microanalysis detector (SEM-EDS), Infrared Spectroscopy (FTIR) and X-Ray powder Diffraction (XRD). The pigments used have been identified and the data obtained suggest the presence of three rustic villas richly decorated also with Egyptian blue. The presence of white of aragonite suggest that these villas were decorated during the Imperial Age, in agreement with the recovery of high quality materials and a bronze statue.

The functionalization of limonite to prepare NZVI and its application in decomposition of p-nitrophenol

NASA Astrophysics Data System (ADS)

Liu, Haibo; Chen, Tianhu; Xie, Qiaoqin; Zou, Xuehua; Chen, Chen; Frost, Ray L.

2015-09-01

Nano zero valent iron (NZVI) was prepared by reducing natural limonite using hydrogen. X-ray fluorescence, thermogravimetry, X-ray diffraction, transmission electron microscope, temperature programmed reduction (TPR), field emission scanning electron microscope/energy disperse spectroscopy (FESEM/EDS) were utilized to characterize the natural limonite and reduced limonite. The ratios of Fe:O before and after reducing was determined using EDS. The reactivity of the NZVI was assessed by decomposition of p-nitrophenol ( p-NP) and was compared with commercial iron powder. In this study, the results of TPR and FESEM/EDS indicated that NZVI can be prepared by reducing natural limonite using hydrogen. Most importantly, this NZVI was proved to have a good performance on decomposition of p-NP and the process of p-NP decomposition agreed well with the pseudo-first-order kinetic model. The reactivity of this NZVI for decomposition of p-NP was greatly superior to that of commercial iron powder.

Visible-light-assisted SLCs template synthesis of sea anemone-like Pd/PANI nanocomposites with high electrocatalytic activity for methane oxidation in acidic medium

NASA Astrophysics Data System (ADS)

Tan, De-Xin; Wang, Yan-Li

2018-03-01

Sea anemone-like palladium (Pd)/polyaniline (PANI) nanocomposites were synthesized via visible-light-assisted swollen liquid crystals (SLCs) template method. The resulting samples were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectrometer (EDS), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV–vis) absorption spectroscopy and Fourier transform infrared (FT-IR) spectroscopy, respectively. The electrocatalytic properties of Pd/PANI nanocomposites modified glass carbon electrode (GCE) for methane oxidation were investigated by cycle voltammetry (CV) and chronoamperometry. Those dispersed sea anemone-like Pd/PANI nanocomposites had an average diameter of 320 nm. The obtained Pd nanoparticles with an average diameter of about 45 nm were uniformly distributed in PANI matrix. Sea anemone-like Pd/PANI nanocomposites exhibited excellent electrocatalytic activity and stability for oxidation of methane (CH4).

Thin single-crystalline Bi2(Te1-xSex)3 ternary nanosheets synthesized by a solvothermal technique

NASA Astrophysics Data System (ADS)

Guo, Jing; Jian, Jikang; Zhang, Zhihua; Wu, Rong; Li, Jin; Sun, Yanfei

2016-01-01

Bi2(Te1-xSex)3 ternary nanosheets have been successfully synthesized through a facile solvothermal technique using diethylenetriamine as solvent, where x can vary from 0 to 1. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) indicate that the as-synthesized Bi2(Te1-xSex)3 samples are nanosheets with rhombohedral structure, and the thickness of the nanosheets can be as thin as several nanometers. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) reveal that the nanosheets are single crystalline with a rhombohedral structure. Energy disperse spectroscopy (EDS) and XRD analysis by Vegard's law confirm that the ternary Bi2(Te1-xSex)3 nanosheets have been obtained here. The growth of the nanosheets is discussed based on an amine-based molecular template mechanism that has been employed to synthesize some other metal chalcogenides.

Coal emissions adverse human health effects associated with ultrafine/nano-particles role and resultant engineering controls.

PubMed

Oliveira, Marcos L S; Navarro, Orlando G; Crissien, Tito J; Tutikian, Bernardo F; da Boit, Kátia; Teixeira, Elba C; Cabello, Juan J; Agudelo-Castañeda, Dayana M; Silva, Luis F O

2017-10-01

There are multiple elements which enable coal geochemistry: (1) boiler and pollution control system design parameters, (2) temperature of flue gas at collection point, (3) feed coal and also other fuels like petroleum coke, tires and biomass geochemistry and (4) fuel feed particle size distribution homogeneity distribution, maintenance of pulverisers, etc. Even though there is a large number of hazardous element pollutants in the coal-processing industry, investigations on micrometer and nanometer-sized particles including their aqueous colloids formation reactions and their behaviour entering the environment are relatively few in numbers. X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/ (Energy Dispersive Spectroscopy) EDS/ (selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis were used as an integrated characterization techniques tool box to determine both geochemistry and nanomineralogy for coal fly ashes (CFAs) from Brazil´s largest coal power plant. Ultrafine/nano-particles size distribution from coal combustion emissions was estimated during the tests. In addition the iron and silicon content was determined as 54.6% of the total 390 different particles observed by electron bean, results aimed that these two particles represent major minerals in the environment particles normally. These data may help in future investigations to asses human health actions related with nano-particles. Copyright © 2017 Elsevier Inc. All rights reserved.

Advances in Chemical and Structural Characterization of Concretion with Implications for Modeling Marine Corrosion

NASA Astrophysics Data System (ADS)

Johnson, Donald L.; DeAngelis, Robert J.; Medlin, Dana J.; Carr, James D.; Conlin, David L.

2014-05-01

The Weins number model and concretion equivalent corrosion rate methodology were developed as potential minimum-impact, cost-effective techniques to determine corrosion damage on submerged steel structures. To apply the full potential of these technologies, a detailed chemical and structural characterization of the concretion (hard biofouling) that transforms into iron bearing minerals is required. The fractions of existing compounds and the quantitative chemistries are difficult to determine from x-ray diffraction. Environmental scanning electron microscopy was used to present chemical compositions by means of energy-dispersive spectroscopy (EDS). EDS demonstrates the chemical data in mapping format or in point or selected area chemistries. Selected-area EDS data collection at precise locations is presented in terms of atomic percent. The mechanism of formation and distribution of the iron-bearing mineral species at specific locations will be presented. Based on water retention measurements, porosity in terms of void volume varies from 15 v/o to 30 v/o (vol.%). The void path displayed by scanning electron microscopy imaging illustrates the tortuous path by which oxygen migrates in the water phase within the concretion from seaside to metalside.

Tetraethylorthosilicate (TEOS) applied in the surface modification of hydroxyapatite to develop polydimethylsiloxane/hydroxyapatite composites.

PubMed

Bareiro, O; Santos, L A

2014-03-01

Nanometric hydroxyapatite (HAp) particles were modified with 5 or 10 wt.% tetraethylorthosilicate (TEOS) solutions in order to prepare polydimethylsiloxane/hydroxyapatite (PDMS/HAp) composites. The surface modification of the HAp particles was studied by transmission electron spectroscopy (TEM) and by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) equipment. The dispersion state of the modified particles in the PDMS matrix was also assessed by SEM. The composite phase composition was characterized by X-ray diffraction (XRD). The composite thermodynamic parameters of cross-linking were analyzed by differential scanning calorimetry (DSC). TEM micrographs and EDS spectra indicated evidence of silica-coating formation on the surface of modified HAp particles. SEM results showed that the HAp particles formed agglomerates in the PDMS matrix. It was found that the introduction of HAp particles into the PDMS changed the enthalpy of cross-linking and the temperature of the beginning of the cross-linking reaction. EDS results indicated that the surface modification of HAp produced composites showing thermodynamic parameters that were more similar to those of unfilled PDMS. Copyright © 2013 Elsevier B.V. All rights reserved.

Ti, Ni and TiNi nanoparticles physically synthesized by Ar+ beam milling.

PubMed

Torres Castro, A; López Cuéllar, E; José Yacamán, M; Ortiz Méndez, U

2008-12-01

When the size of a particle decreases around 100 nm or less, there is a change in properties from those shown in the bulk material. In this work approximately 3 nm nanoparticles of Ni, Ti and TiNi bimetallic are produced using physical vapor deposition (PVD). Nanoparticles are characterized by High Resolution Transmission Electron Microscopy (HRTEM), High Angle Annular Dark Field (HAADF), Electron Diffraction (ED). The results show that all nanoparticles maintain the same crystal structure of bulk material but a change in their lattice parameter is produced.

Nanoscale interfacial mixing of Au/Bi layers using MeV ion beams

NASA Astrophysics Data System (ADS)

Prusty, Sudakshina; Siva, V.; Ojha, S.; Kabiraj, D.; Sahoo, P. K.

2017-05-01

We have studied nanoscale mixing of thermally deposited double bilayer films of Au/Bi after irradiating them by 1.5 MeV Au2+ ions. Post irradiation effects on the morphology and elemental identification in these films are studied by Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). Glancing angle X-ray diffraction (GAXRD) of the samples indicate marginal changes in the irradiated samples due to combined effect of nuclear and electronic energy loss. The interfacial mixing is studied by Rutherford backscattering (RBS).

Microstructural Study of Micron-Sized Craters Simulating Stardust Impacts in Aluminum 1100 Targets

NASA Technical Reports Server (NTRS)

Leroux, Hugues; Borg, Janet; Troadec, David; Djouadi, Zahia; Horz, Friedrich

2006-01-01

Various microscopic techniques were used to characterize experimental micro- craters in aluminium foils to prepare for the comprehensive analysis of the cometary and interstellar particle impacts in aluminium foils to be returned by the Stardust mission. First, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive X-ray Spectroscopy) were used to study the morphology of the impact craters and the bulk composition of the residues left by soda-lime glass impactors. A more detailed structural and compositional study of impactor remnants was then performed using TEM (Transmission Electron Microscopy), EDS, and electron diffraction methods. The TEM samples were prepared by Focused Ion Beam (FIB) methods. This technique proved to be especially valuable in studying impact crater residues and impact crater morphology. Finally, we also showed that InfraRed microscopy (IR) can be a quick and reliable tool for such investigations. The combination of all of these tools enables a complete microscopic characterization of the craters.

Electron microscopy characterization of Ni-Cr-B-Si-C laser deposited coatings.

PubMed

Hemmati, I; Rao, J C; Ocelík, V; De Hosson, J Th M

2013-02-01

During laser deposition of Ni-Cr-B-Si-C alloys with high amounts of Cr and B, various microstructures and phases can be generated from the same chemical composition that results in heterogeneous properties in the clad layer. In this study, the microstructure and phase constitution of a high-alloy Ni-Cr-B-Si-C coating deposited by laser cladding were analyzed by a combination of several microscopy characterization techniques including scanning electron microscopy in secondary and backscatter imaging modes, energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The combination of EDS and EBSD allowed unequivocal identification of micron-sized precipitates as polycrystalline orthorhombic CrB, single crystal tetragonal Cr5B3, and single crystal hexagonal Cr7C3. In addition, TEM characterization showed various equilibrium and metastable Ni-B, Ni-Si, and Ni-Si-B eutectic products in the alloy matrix. The findings of this study can be used to explain the phase formation reactions and to tune the microstructure of Ni-Cr-B-Si-C coatings to obtain the desired properties.

Synthesis and characterization of hollow spherical copper phosphide (Cu 3P) nanopowders

NASA Astrophysics Data System (ADS)

Liu, Shuling; Qian, Yitai; Xu, Liqiang

2009-03-01

In this paper, hollow spherical Cu 3P nanopowders were synthesized by using copper sulfate pentahydrate (CuSO 4ṡ5H 2O) and yellow phosphorus in a mixed solvent of glycol, ethanol and water at 140-180 ∘C for 12 h. X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), electron diffraction pattern (ED) and transmission electronic microscopy (TEM) studies show that the as-synthesized nanocrystal is pure hexagonal phase Cu 3P with a hollow spherical morphology. Based on the TEM observations, a possible aggregation growth mechanism was proposed for the formation of Cu 3P hollow structures. Meanwhile, the effects of some key factors such as solvents, reaction temperature and reaction time on the final formation of the Cu 3P hollow structure were also discussed.

Synthesis of ZnO Hexagonal Micro Discs on Glass Substrates Using the Spray Pyrolysis Technique

NASA Astrophysics Data System (ADS)

Ikhmayies, Shadia J.; Zbib, Mohamad B.

2017-07-01

Zinc oxide (ZnO) is an important transparent conducting oxide of potential use in solar cells, electronics, photoelectronics, and sensors. In this work ZnO micro discs were synthesized in thin film form on glass substrates using the low cost spray pyrolysis method. The films were prepared from a precursor solution of ZnCl2 in distilled water at a substrate temperature of 300 ± 5°C. The as-synthesized samples were analyzed with x-ray diffraction, scanning electron microscopy, and x-ray energy dispersive spectroscopy (EDS). The morphology of the films showed randomly distributed micro discs of hexagonal shape. The EDS reports showed that the films contained Cl and Fe. Size analysis was performed using ImageJ software, where the average diameter was found to be 4.8 ± 0.9 μm, and the average thickness was found to be 254 ± 43 nm.

The effects of ageing time on the microstructure and properties of mesoporous silica-hydroxyapatite nanocomposite

NASA Astrophysics Data System (ADS)

Yousefpour, Mardali; Taherian, Zahra

2013-02-01

In this study, a mesoporous silica-hydroxyapatite nanocomposite (MCM-41/HA) was synthesized via sol-gel technique as a drug delivery system. The synthesis of MCM-41/hydroxyapatite nanocomposite was carried out at room temperature. The effect of various ageing time on the nanocomposite properties was studied during synthesis process. 0, 24, 36, and 48 h aging times were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Electron Diffraction pattern (ED), and N2 adsorption-desorption. Results showed that ageing process led to HA crystals nucleation and growth on the surface of mesoporous silica. At 48 h of aging time, the surface area and total pore volume increased from 36.2 to 334 m2/g and 0.14-0.7 cm3/g, respectively. In contrast, the average pore diameter considerably decreased from 20.1 nm for (MCM-41/HA)24 to 8.39 nm for (MCM-41/HA)48. Furthermore, it was observed more homogeneous pore distribution with increasing the ageing time. In conclusion, the ageing time play an important role on textural properties of MCM-41/HA nanocomposite which could have a major effect on drug delivery properties such as molecular loading and release kinetics.

Electron Beam Welding of IN792 DS: Effects of Pass Speed and PWHT on Microstructure and Hardness.

PubMed

Angella, Giuliano; Barbieri, Giuseppe; Donnini, Riccardo; Montanari, Roberto; Richetta, Maria; Varone, Alessandra

2017-09-05

Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds ( v ) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests. In the as-welded condition; the structure of directionally oriented grains was completely lost in MZ. The γ' phase in MZ consisted of small (20-40 nm) round shaped particles and its total amount depended on both PHT and welding pass speed, whereas in HAZ, it was the same BM. Even if the amount of γ' phase in MZ was lower than that of the as-received material, the nanometric size of the particles induced an increase in hardness. EDS examinations did not show relevant composition changes in the γ' and γ phases. Post-welding heat treatments (PWHT) at 700 and 750 °C for two hours were performed on the best samples. After PWHTs, the amount of the ordered phase increased, and the effect was more pronounced at 750 °C, while the size of γ' particles in MZ remained almost the same. The hardness profiles measured across the joints showed an upward shift, but peak-valley height was a little lower, indicating more homogeneous features in the different zones.

Facile green synthesis of fluorescent N-doped carbon dots from Actinidia deliciosa and their catalytic activity and cytotoxicity applications

NASA Astrophysics Data System (ADS)

Arul, Velusamy; Sethuraman, Mathur Gopalakrishnan

2018-04-01

Green synthesis of fluorescent nitrogen doped carbon dots (N-CDs) using Actinidia deliciosa (A. deliciosa) fruit extract as a carbon precursor and aqueous ammonia as a nitrogen dopant is reported here. The synthesized N-CDs were characterized by high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), UV-Visible spectroscopy (UV-Vis), fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The average size of the N-CDs was approximately 3.59 nm and the calculated inter layer distance was found to be 0.21 nm. Raman spectroscopy and SAED pattern revealed the graphitic nature of the synthesized N-CDs. The N-CDs were found to emit intense blue color at 405 nm under the excitation of 315 nm. The doping of nitrogen over the surface of the N-CDs was confirmed by EDS, FT-IR and XPS studies. The synthesized N-CDs were found to exhibit excellent catalytic activity in the reduction of Rhodamine-B using sodium borohydrate. The MTT assay was used to evaluate the cytotoxicity and biocompatibility of N-CDs towards L-929 and MCF-7 cells. From the results obtained, it was found that the N-CDs exhibit low cytotoxicity and superior biocompatibility on both L-929 and MCF-7 cells.

Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM).

PubMed

Liu, Airong; Zhang, Wei-xian

2014-09-21

An angstrom-resolution physical model of nanoscale zero-valent iron (nZVI) is generated with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) on the Fe L-edge. Bright-field (BF), high-angle annular dark-field (HAADF) and secondary electron (SE) imaging of nZVI acquired by a Hitachi HD-2700 STEM show near atomic resolution images and detailed morphological and structural information of nZVI. The STEM-EDS technique confirms that the fresh nZVI comprises of a metallic iron core encapsulated with a thin layer of iron oxides or oxyhydroxides. SAED patterns of the Fe core suggest the polycrystalline structure in the metallic core and amorphous nature of the oxide layer. Furthermore, Fe L-edge of EELS shows varied structural features from the innermost Fe core to the outer oxide shell. A qualitative analysis of the Fe L(2,3) edge fine structures reveals that the shell of nZVI consists of a mixed Fe(II)/Fe(III) phase close to the Fe (0) interface and a predominantly Fe(III) at the outer surface of nZVI.

Chrome-free Samarium-based Protective Coatings for Magnesium Alloys

NASA Astrophysics Data System (ADS)

Hou, Legan; Cui, Xiufang; Yang, Yuyun; Lin, Lili; Xiao, Qiang; Jin, Guo

The microstructure of chrome-free samarium-based conversion coating on magnesium alloy was investigated and the corrosion resistance was evaluated as well. The micro-morphology, transverse section, crystal structure and composition of the coating were observed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X- ray photoelectron spectroscopy (XPS), respectively. The corrosion resistance was evaluated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The results reveal that the morphology of samarium conversion coating is of crack-mud structure. Tiny cracks distribute in the compact coating deposited by samarium oxides. XRD, EDS and XPS results characterize that the coating is made of amorphous and trivalent-samarium oxides. The potentiodynamic polarization curve, EIS and OCP indicate that the samarium conversion coating can improve the corrosion resistance of magnesium alloys.

High Resolution Transmission Electron Microscopy (HRTEM) of nanophase ferric oxides

NASA Technical Reports Server (NTRS)

Golden, D. C.; Morris, R. V.; Ming, D. W.; Lauer, H. V., Jr.

1994-01-01

Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Martian analog ferric oxide minerals of submicron or nanometer size range. Out of the iron oxide minerals studied, nanometer sized ferric oxides are promising candidates for possible Martian spectral analogs. 'Nanophase ferric oxide (np-Ox)' is a generic term for ferric oxide/oxihydroxide particles having nanoscale (less than 10 nm) particle dimensions. Ferrihydrite, superparamagnetic particles of hematite, maghemite and goethite, and nanometer sized particles of inherently paramagnetic lepidocrocite are all examples of nanophase ferric oxides. np-Ox particles in general do not give X-ray diffraction (XRD) patterns with well defined peaks and would often be classified as X-ray amorphous. Therefore, different np-Oxs preparations should be characterized using a more sensitive technique e.g., high resolution transmission electron microscopy (HRTEM). The purpose of this study is to report the particle size, morphology and crystalline order, of five np-Ox samples by HRTEM imaging and electron diffraction (ED).

Synthesis and characterization of single-crystalline zinc tin oxide nanowires

NASA Astrophysics Data System (ADS)

Shi, Jen-Bin; Wu, Po-Feng; Lin, Hsien-Sheng; Lin, Ya-Ting; Lee, Hsuan-Wei; Kao, Chia-Tze; Liao, Wei-Hsiang; Young, San-Lin

2014-05-01

Crystalline zinc tin oxide (ZTO; zinc oxide with heavy tin doping of 33 at.%) nanowires were first synthesized using the electrodeposition and heat treatment method based on an anodic aluminum oxide (AAO) membrane, which has an average diameter of about 60 nm. According to the field emission scanning electron microscopy (FE-SEM) results, the synthesized ZTO nanowires are highly ordered and have high wire packing densities. The length of ZTO nanowires is about 4 μm, and the aspect ratio is around 67. ZTO nanowires with a Zn/(Zn + Sn) atomic ratio of 0.67 (approximately 2/3) were observed from an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrated that the ZTO nanowire is hexagonal single-crystalline. The study of ultraviolet/visible/near-infrared (UV/Vis/NIR) absorption showed that the ZTO nanowire is a wide-band semiconductor with a band gap energy of 3.7 eV.

Synthesis and characterization of single-crystalline zinc tin oxide nanowires.

PubMed

Shi, Jen-Bin; Wu, Po-Feng; Lin, Hsien-Sheng; Lin, Ya-Ting; Lee, Hsuan-Wei; Kao, Chia-Tze; Liao, Wei-Hsiang; Young, San-Lin

2014-01-01

Crystalline zinc tin oxide (ZTO; zinc oxide with heavy tin doping of 33 at.%) nanowires were first synthesized using the electrodeposition and heat treatment method based on an anodic aluminum oxide (AAO) membrane, which has an average diameter of about 60 nm. According to the field emission scanning electron microscopy (FE-SEM) results, the synthesized ZTO nanowires are highly ordered and have high wire packing densities. The length of ZTO nanowires is about 4 μm, and the aspect ratio is around 67. ZTO nanowires with a Zn/(Zn + Sn) atomic ratio of 0.67 (approximately 2/3) were observed from an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrated that the ZTO nanowire is hexagonal single-crystalline. The study of ultraviolet/visible/near-infrared (UV/Vis/NIR) absorption showed that the ZTO nanowire is a wide-band semiconductor with a band gap energy of 3.7 eV.

Development of Cu Reinforced SiC Particulate Composites

NASA Astrophysics Data System (ADS)

Singh, Harshpreet; Kumar, Lailesh; Nasimul Alam, Syed

2015-02-01

This paper presents the results of Cu-SiCp composites developed by powder metallurgy route and an attempt has been made to make a comparison between the composites developed by using unmilled Cu powder and milled Cu powder. SiC particles as reinforcement was blended with unmilled and as-milled Cu powderwith reinforcement contents of 10, 20, 30, 40 vol. % by powder metallurgy route. The mechanical properties of pure Cu and the composites developed were studied after sintering at 900°C for 1 h. Density of the sintered composites were found out based on the Archimedes' principle. X-ray diffraction of all the composites was done in order to determine the various phases in the composites. Scanning electron microscopy (SEM) and EDS (electron diffraction x-ray spectroscopy) was carried out for the microstructural analysis of the composites. Vickers microhardness tester was used to find out the hardness of the samples. Wear properties of the developed composites were also studied.

Synthesis of CdS nanorods in soft template under gamma-irradiation.

PubMed

Zhao, Bing; Wang, Yanli; Zhang, Haijiao; Jiao, Zheng; Wang, Haobo; Ding, Guoji; Wu, Minghong

2009-02-01

CdS nano material which has a band gap of 2.42 eV at room temperature is a typical II-VII semiconductor having many commercial or potential applications, e.g., light-emitting diodes, solar cell and optoelectronic devices. In this paper, we use a new strategy to synthesize CdS nanorods. CdS nanorods were prepared in soft template under gamma-irradiation though the reaction of cadmium sulphide and thiacetamide (TAA). The formation process and characters of CdS nanorods was investigated in detail by transmission electron microscopy (TEM), electron diffraction (ED) pattern, X-ray powder diffraction (XRD), ultraviolet spectrophotometer (UV) and photoluminescence spectrophotometer (PL). In the experiment we proposed that the irradiation of gamma-ray accelerated the formation of S(2-) under acidic condition (pH = 3) and vinyl acetate (VAc) monomer formed pre-organized nano polymer tubules which were used as both templates and nanoreacters for the growth of CdS nanorods. In this process, we have obtained the CdS polycrystal nanorods with PVAc nano tubules and CdS single-crystal nanorods. The result of X-ray powder diffraction confirms that the crystal type of CdS nanorods is cubic F-43 m (216). The results from transmission electron microscopy and electron diffraction show that the concentrations of reactants and the dose rate of gamma-ray are key to produce appropriate CdS nanorods. Relatively low concentrations (Cd2+: 0.008-0.02 mol/L, Cd2+ : S(2-) = 1 : 2) of reactants and long time (1-2 d) of irradiation in low dose rate (6-14 Gy/min) are propitious to form CdS single-crystal nanorods with small diameter (less than 100 nm) and well length (2-5 microm). UV and PL characterizations show the sample have well optical properties.

Nano-mineralogy of suspended sediment during the beginning of coal rejects spill.

PubMed

Civeira, Matheus S; Ramos, Claudete G; Oliveira, Marcos L S; Kautzmann, Rubens M; Taffarel, Silvio R; Teixeira, Elba C; Silva, Luis F O

2016-02-01

Ultrafine and nanometric sediment inputs into river systems can be a major source of nutrients and hazardous elements and have a strong impact on water quality and ecosystem functions of rivers and lakes regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in South America. The objective of this work was to study the coal cleaning rejects (CCRs) spill that occurred from a CCRs impoundment pond into the Tubarão River, South Brazil, provided a unique occasion to study the importance and role of incidental nanoparticles associated with pollutant dispersal from a large-scale, acute aquatic pollution event. Multifaceted geochemical research by X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS, and Raman spectroscopy, provided an in-depth understanding of importance of a nano-mineralogy approach of Aqueous Pollution Scenarios. The electron beam studies showed the presence of a number of potentially hazardous elements (PHEs) in nanoparticles (amorphous and minerals). Some of the neoformed ultrafine/nanoparticles found in the contaminated sediments are the same as those commonly associated with oxidation/transformation of oxides, silicates, sulfides, and sulfates. These data of the secondary ultra/nanoparticles, puts in evidence their ability to control the mobility of PHEs, suggesting possible presentations in environmental technology, including recuperation of sensitive coal mine. The developed methodology facilitated the sediment transport of the catchment providing consistent results and suggesting its usefulness as a tool for temporary rivers management. Copyright © 2015 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basak, Sushovan, E-mail: sushovanbasak@gmail.com; Das, Hrishikesh, E-mail: hrishichem@gmail.com; Pal, Tapan Kumar, E-mail: tkpal.ju@gmail.com

In order to meet the demand for lighter and more fuel efficient vehicles, a significant attempt is currently being focused toward the substitution of aluminum for steel in the car body structure. It generates vital challenge with respect to the methods of joining to be used for fabrication. However, the conventional fusion joining has its own difficulty owing to formation of the brittle intermetallic phases. In this present study AA6061-T6 of 2 mm and HIF-GA steel sheet of 1 mm thick are metal inert gas (MIG) brazed with 0.8 mm Al–5Si filler wire under three different heat inputs. The effectmore » of the heat inputs on bead geometry, microstructure and joint properties of MIG brazed Al-steel joints were exclusively studied and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), electron probe micro analyzer (EPMA) and high resolution transmission electron microscopy (HRTEM) assisted X-ray spectroscopy (EDS) and selective area diffraction pattern. Finally microstructures were correlated with the performance of the joint. Diffusion induced intermetallic thickness measured by FESEM image and concentration profile agreed well with the numerically calculated one. HRTEM assisted EDS study was used to identify the large size FeAl{sub 3} and small size Fe{sub 2}Al{sub 5} type intermetallic compounds at the interface. The growth of these two phases in A2 (heat input: 182 J mm{sup −1}) is attributed to the slower cooling rate with higher diffusion time (~ 61 s) along the interface in comparison to the same for A1 (heat input: 155 J mm{sup −1}) with faster cooling rate and shorter diffusion time (~ 24 s). The joint efficiency as high as 65% of steel base metal is achieved for A2 which is the optimized parameter in the present study. - Highlights: • AA 6061 and HIF-GA could be successfully joined by MIG brazing. • Intermetallics are exclusively studied and characterized by XRD, FESEM and EPMA. • Intermetallic formation by diffusion is worth considering or not. • HRTEM-EDS, SAD pattern identifies the morphologies and size of intermetallics. • A compromise concerning formation of IMC is necessary.« less

Effect of ionizing radiation on structural and conductive properties of copper nanotubes

NASA Astrophysics Data System (ADS)

Zdorovets, M. V.; Borgekov, D. B.; Kenzhina, I. E.; Kozlovskiy, A. L.

2018-01-01

The use of electron radiation is an effective tool for stimulating a controlled modification of structural and conductive properties of nanomaterials in modern materials science. The paper presents the results of studies of the influence of various types of radiation on structural and conductive properties of copper nanotubes obtained by electrochemical synthesis in pores of templates based on polyethylene terephthalate. Such methods as SEM, X-ray diffraction and EDS show that irradiation with a stream of high-energy electrons with doses of 50-250 kGy makes it possible to modify the crystal structure of nanotubes, increasing their conductivity and decreasing the resistance of nanostructures without destroying the structure.

Zirconium nitride precipitation in nominally pure yttria-stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.

Nominally pure yttria-stabilized zirconia alloys are shown to contain unexpectedly large amounts of dissolved nitrogen. Its presence in the lattice was detected through the observation of large precipitates in alloys with three different concentrations of yttria deformed in compression in argon in the temperature range 1,600--1,800 C. Electron diffraction, EDS and PEELS analyses, and Moire imaging were used to identify the precipitates as ZrN. The possible origin of the nitrogen, its likely effects on properties, and the role of annealing atmosphere are briefly discussed.

Electron Beam Welding of IN792 DS: Effects of Pass Speed and PWHT on Microstructure and Hardness

PubMed Central

Angella, Giuliano; Montanari, Roberto; Richetta, Maria; Varone, Alessandra

2017-01-01

Electron Beam (EB) welding has been used to realize seams on 2 mm-thick plates of directionally solidified (DS) IN792 superalloy. The first part of this work evidenced the importance of pre-heating the workpiece to avoid the formation of long cracks in the seam. The comparison of different pre-heating temperatures (PHT) and pass speeds (v) allowed the identification of optimal process parameters, namely PHT = 300 °C and v = 2.5 m/min. The microstructural features of the melted zone (MZ); the heat affected zone (HAZ), and base material (BM) were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and micro-hardness tests. In the as-welded condition; the structure of directionally oriented grains was completely lost in MZ. The γ’ phase in MZ consisted of small (20–40 nm) round shaped particles and its total amount depended on both PHT and welding pass speed, whereas in HAZ, it was the same BM. Even if the amount of γ’ phase in MZ was lower than that of the as-received material, the nanometric size of the particles induced an increase in hardness. EDS examinations did not show relevant composition changes in the γ’ and γ phases. Post-welding heat treatments (PWHT) at 700 and 750 °C for two hours were performed on the best samples. After PWHTs, the amount of the ordered phase increased, and the effect was more pronounced at 750 °C, while the size of γ’ particles in MZ remained almost the same. The hardness profiles measured across the joints showed an upward shift, but peak-valley height was a little lower, indicating more homogeneous features in the different zones. PMID:28872620

Microwave-assisted hydrothermal synthesis of biocompatible silver sulfide nanoworms

NASA Astrophysics Data System (ADS)

Xing, Ruimin; Liu, Shanhu; Tian, Shufang

2011-10-01

In this study, silver sulfide nanoworms were prepared via a rapid microwave-assisted hydrothermal method by reacting silver nitrate and thioacetamide in the aqueous solution of the Bovine Serum Albumin (BSA) protein. The morphology, composition, and crystallinity of the nanoworms were characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The results show that the nanoworms were assembled by multiple adjacent Ag2S nanoparticles and stabilized by a layer of BSA attached to their surface. The nanoworms have the sizes of about 50 nm in diameter and hundreds of nanometers in length. The analyses of high-resolution TEM and their correlative Fast Fourier Transform (FFT) indicate that the adjacent Ag2S nanoparticles grow by misoriented attachment at the connective interfaces to form the nanoworm structure. In vitro assays on the human cervical cancer cell line HeLa show that the nanoworms exhibit good biocompatibility due to the presence of BSA coating. This combination of features makes the nanoworms attractive and promising building blocks for advanced materials and devices.

Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

NASA Astrophysics Data System (ADS)

Solehudin, Agus; Nurdin, Isdiriayani

2014-03-01

Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

Rational design of Ag/TiO2 nanosystems by a combined RF-sputtering/sol-gel approach.

PubMed

Armelao, Lidia; Barreca, Davide; Bottaro, Gregorio; Gasparotto, Alberto; Maccato, Chiara; Tondello, Eugenio; Lebedev, Oleg I; Turner, Stuart; Van Tendeloo, Gustaaf; Sada, Cinzia; Stangar, Urska Lavrencic

2009-12-21

The present work is devoted to the preparation of Ag/TiO(2) nanosystems by an original synthetic strategy, based on the radio-frequency (RF) sputtering of silver particles on titania-based xerogels prepared by the sol-gel (SG) route. This approach takes advantage of the synergy between the microporous xerogel structure and the infiltration power characterizing RF-sputtering, whose combination enables the obtainment of a tailored dispersion of Ag-containing particles into the titania matrix. In addition, the system's chemico-physical features can be tuned further through proper ex situ thermal treatments in air at 400 and 600 degrees C. The synthesized composites are extensively characterized by the joint use of complementary techniques, that is, X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), secondary ion mass spectrometry (SIMS), glancing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), electron diffraction (ED), high-angle annular dark field scanning TEM (HAADF-STEM), energy-filtered TEM (EF-TEM) and optical absorption spectroscopy. Finally, the photocatalytic performances of selected samples in the decomposition of the azo-dye Plasmocorinth B are preliminarily investigated. The obtained results highlight the possibility of tailoring the system characteristics over a broad range, directly influencing their eventual functional properties.

Investigations of the Failure in Boilers Economizer Tubes Used in Power Plants

NASA Astrophysics Data System (ADS)

Moakhar, Roozbeh Siavash; Mehdipour, Mehrad; Ghorbani, Mohammad; Mohebali, Milad; Koohbor, Behrad

2013-09-01

In this study, failure of a high pressure economizer tube of a boiler used in gas-Mazut combined cycle power plants was studied. Failure analysis of the tube was accomplished by taking into account visual inspection, thickness measurement, and hardness testing as well as microstructural observations using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Optical microscopy images indicate that there is no phase transformation during service, and ferrite-pearlite remained. The results of XRD also revealed Iron sulfate (FeSO4) and Iron hydroxide sulfate (FeOH(SO4)) phases formed on the steel surface. A considerable amount of Sulfur was also detected on the outer surface of the tube by EDS analysis. Dew-point corrosion was found to be the principal reason for the failure of the examined tube while it has been left out-of-service.

Biological and catalytic applications of green synthesized fluorescent N-doped carbon dots using Hylocereus undatus.

PubMed

Arul, Velusamy; Edison, Thomas Nesakumar Jebakumar Immanuel; Lee, Yong Rok; Sethuraman, Mathur Gopalakrishnan

2017-03-01

In this work, a simple hydrothermal route for the synthesis of fluorescent nitrogen doped carbon dots (N-CDs) is reported. The Hylocereus undatus (H. undatus) extract and aqueous ammonia are used as carbon and nitrogen source, respectively. The optical properties of synthesized N-CDs are analyzed using UV-Visible (UV-Vis) and fluorescence spectroscopy. The surface morphology, elemental composition, crystallinity and functional groups present in the N-CDs are examined using high resolution transmission electron microscopy (HR-TEM) with energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy, respectively. The synthesized N-CDs emit strong blue fluorescence at 400nm under the excitation of 320nm. Further, the excitation dependent emission properties are also observed from the fluorescence of synthesized N-CDs. The HR-TEM results reveal that synthesized N-CDs are in spherical shape with average diameter of 2.5nm. The XRD pattern exhibits, the graphitic nature of synthesized N-CDs. The doping of nitrogen is confirmed from the EDS and FT-IR studies. The cytotoxicity and biocompatibility of N-CDs are evaluated through MTT assay on L-929 (Lymphoblastoid-929) and MCF-7 (Michigan Cancer Foundation-7) cells. The results indicate that the fluorescent N-CDs show less cytotoxicity and good biocompatibility on both L-929 and MCF-7 cells. Moreover, the N-CDs show excellent catalytic activity towards the reduction of methylene blue by sodium borohydride. Copyright © 2017 Elsevier B.V. All rights reserved.

High quality transmission Kikuchi diffraction analysis of deformed alloys - Case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokarski, Tomasz, E-mail: tokarski@agh.edu.pl

Modern scanning electron microscopes (SEM) equipped with thermally assisted field emission guns (Schottky FEG) are capable of imaging with a resolution in the range of several nanometers or better. Simultaneously, the high electron beam current can be used, which enables fast chemical and crystallographic analysis with a higher resolution than is normally offered by SEM with a tungsten cathode. The current resolution that limits the EDS and EBSD analysis is related to materials' physics, particularly to the electron-specimen interaction volume. The application of thin, electron-transparent specimens, instead of bulk samples, improves the resolution and allows for the detailed analysis ofmore » very fine microstructural features. Beside the typical imaging mode, it is possible to use a standard EBSD camera in such a configuration that only transmitted and scattered electrons are detected. This modern approach was successfully applied to various materials giving rise to significant resolution improvement, especially for the light element magnesium based alloys. This paper presents an insight into the application of the transmission Kikuchi diffraction (TKD) technique applied to the most troublesome, heavily-deformed materials. In particular, the values of the highest possible acquisition rates for high resolution and high quality mapping were estimated within typical imaging conditions of stainless steel and magnesium-yttrium alloy. - Highlights: •Monte Carlo simulations were used to simulate EBSD camera intensity for various measuring conditions. •Transmission Kikuchi diffraction parameters were evaluated for highly deformed, light and heavy elements based alloys. •High quality maps with 20 nm spatial resolution were acquired for Mg and Fe based alloys. •High speed TKD measurements were performed at acquisition rates comparable to the reflection EBSD.« less

Properties of magnetic iron oxides used as materials for wastewater treatment

NASA Astrophysics Data System (ADS)

Matei, E.; Predescu, A.; Vasile, E.; Predescu, A.

2011-07-01

The paper describes the properties of some nanopowders obtained by coprecipitation and used as adsorbent for wastewater treatment. The Fe3O4 and γ-Fe2O3 nanopowders were obtained using iron salts and NaOH as precipitation agents. D-sorbitol was used to prevent the agglomeration between the nanoparticles. The particle size and distribution were detected using a transmission electron microscopy (TEM) and a scanning electron microscope (SEM) equipped with dispersive analyze system in X radiation energy (EDS). The structure of the iron oxide nanoparticles was characterized by X-ray powder diffraction. Thus, the nanoparticles were characterized and compare in terms of particle size and chemical composition and used for adsorption studies in order to removal hexavalent chromium from waste waters.

Flux Growth of Highly Crystalline Photocatalytic BaTiO3 Particle Layers on Porous Titanium Sponge Substrate and Insights into the Formation Mechanism

NASA Astrophysics Data System (ADS)

Wang, Q.; Li, B.

2017-09-01

A unique architecture of idiomorphic and highly crystalline BaTiO3 particle layers directly grown on a porous titanium sponge substrate was successfully achieved for the first time using a facile molten salt method at a relatively low temperature of 700 °C. Specifically, the low-melting KCl-NaCl eutectic salts and barium hydroxide octahydrate were employed as the reaction medium and barium source, respectively. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectrophotometry were used to characterize the structure, morphology and optical property of the obtained samples. The results revealed that the flux-grown tetragonal BaTiO3 products had well-defined and uniform morphology with an average size of 300 nm and a band gap of ∼3.16 eV. Based on XRD, EDS, SEM, and TEM, the possible formation mechanism responsible for the well-developed architecture of BaTiO3 particle layers was proposed and discussed. Furthermore, the photocatalytic activity of the flux-grown BaTiO3 products for organic pollutant degradation under simulated sunlight irradiation was also investigated.

Pseudomorphic to orthomorphic growth of Fe films on Cu3Au(001)

NASA Astrophysics Data System (ADS)

Bruno, F.; Terreni, S.; Floreano, L.; Cossaro, A.; Cvetko, D.; Luches, P.; Mattera, L.; Morgante, A.; Moroni, R.; Repetto, M.; Verdini, A.; Canepa, M.

2002-06-01

The structure of Fe films grown on the (001) surface of a Cu3Au single crystal at room temperature has been investigated by means of grazing incidence x-ray diffraction (GIXRD) and photo/Auger-electron diffraction (ED) as a function of thickness in the (3-36)-Å range. The combination of GIXRD and ED allows one to obtain quantitative information on the in-plane spacing a from the former technique, and the ratio between the vertical spacing c and a, from the latter one. At low coverage the film grows pseudomorphic to the face-centered-cubic substrate. The experimental results obtained on a film of 8 Å thickness clearly indicate the overcoming of the limit for pseudomorphic growth. Above this limit the film is characterized by the coexistence of the pseudomorphic phase with another tetragonally strained phase γ, which falls on the epitaxial line of ferromagnetic face-centered cubic Fe. Finally, the development of a body-centered phase α, whose unit cell is rotated by 45° with respect to the substrate one, has been clearly observed at ~17 Å. α is the dominating phase for film thickness above ~25 Å and its lattice constant evolves towards the orthomorphic phase in strict quantitative agreement with epitaxial curves calculated for body-centered tetragonal iron phases.

Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

PubMed

Zamudio-Ortega, C M; Contreras-Bulnes, R; Scougall-Vilchis, R J; Morales-Luckie, R A; Olea-Mejía, O F; Rodríguez-Vilchis, L E

2014-09-01

The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

Electroless Nickel Deposition for Front Side Metallization of Silicon Solar Cells

PubMed Central

Hsieh, Shu Huei; Hsieh, Jhong Min; Chen, Wen Jauh; Chuang, Chia Chih

2017-01-01

In this work, nickel thin films were deposited on texture silicon by electroless plated deposition. The electroless-deposited Ni layers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and sheet resistance measurement. The results indicate that the dominant phase was Ni2Si and NiSi in samples annealed at 300–800 °C. Sheet resistance values were found to correlate well with the surface morphology obtained by SEM and the results of XRD diffraction. The Cu/Ni contact system was used to fabricate solar cells by using two different activating baths. The open circuit voltage (Voc) of the Cu/Ni samples, before and after annealing, was measured under air mass (AM) 1.5 conditions to determine solar cell properties. The results show that open circuit voltage of a solar cell can be enhanced when the activation solution incorporated hydrofluoric acid (HF). This is mainly attributed to the native silicon oxide layer that can be decreased and/or removed by HF with the corresponding reduction of series resistance. PMID:28805724

Evaluation of local anesthetic effects of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles in Male Swiss mice.

PubMed

Jiang, Qiliang; Yu, Shashuang; Li, Xingwang; Ma, Chuangen; Li, Aixiang

2018-01-01

A simple approach for the synthesis of Lidocaine-Ibuprofen ionic liquid stabilized silver nanoparticles (IL-AgNPs) was reported in this work. The shape, size and surface morphology of the Lidocaine-Ibuprofen ionic liquid stabilized AgNPs were characterized by using spectroscopic and microscopic techniques such as Ultraviolet-visible spectroscopy (UV-Visible), X-ray diffraction (XRD) analysis, Selected area electron diffraction (SAED), Transmission electron microscopy (TEM). TEM analysis showed the formation of 20-30nm size of IL-AgNPs with very clear lattice fringes. SAED pattern confirmed the highly crystalline nature of fabricated IL stabilized AgNPs. EDS results confirmed the formation of nanosilver. The fabricated IL-AgNPs were studied for their local anesthetic effect in rats. The results of local anesthetic effect showed that the time for onset of action by IL-AgNPs is 10min, which is significantly higher than that for EMLA. Further, tactile test results confirmed the stronger and faster local anesthetic effect of IL-AgNPs when compared to that of EMLA. Copyright © 2017. Published by Elsevier B.V.

Synthesis and luminescence properties of cinnamide based nanohybrid materials containing Eu (II) ions

NASA Astrophysics Data System (ADS)

Kiran Kumar, A. B. V.; Jayasimhadri, M.; Cha, Hyeongrae; Chen, Kuangcai; Lim, Jae-Min; Lee, Yong-Ill

2011-07-01

In the present work, the cinnamide based organic-inorganic hybrid luminescent materials were prepared by using sol-gel technique, in which both the components are covalently linked via Si-C bonds. The organic precursor N-(3-(triethoxysilyl)propyl)cinnamide (Cn-Si) was synthesized by (3-aminopropyl) triethoxysilane being reacted with cinnamoyal chloride. Finally, novel hybrid materials were prepared successfully through hydrolysis and polycondensation processes between the alkoxide groups of precursors Cn-Si and tetraethylorthosilane (TEOS) in the presence of europium nitrate. We have characterized thoroughly the prepared samples using FT-IR, thermal analysis (TGA/DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) and photoluminescence (PL) spectroscopy. The results indicate that these materials exhibit the excellent thermal stability up to 350 °C. The X-ray diffraction patterns confirmed the amorphous nature of the developed materials. The rare-earth doped hybrid materials have exhibited an intense green emission at 530 nm with CIE chromaticity coordinates (0.4801, 0.4669). Whereas, the un-doped one gives some remarkable blue emission properties under UV excitation.

Synthesis and Characterization of the First Liquid Single Source Precursors for the Deposition of Ternary Chalcopyrite (CuInS2) Thin Film Materials

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Cowen, Jonathan; Hepp, Aloysius

2002-01-01

Molecular engineering of ternary single source precursors based on the [{PBu3}2Cu(SR')2In(SR')2] architecture have afforded the first liquid CIS ternary single source precursors (when R = Et, n-Pr), which are suitable for low temperature deposition (< 350 C). Thermogravimetric analyses (TGA) and modulated-differential scanning calorimetry (DSC) confirm their liquid phase and reduced stability. X-ray diffraction studies, energy dispersive analyzer (EDS), and scanning electron microscopy (SEM) support the formation of the single-phase chalcopyrite CuInS2 at low temperatures.

Composition and microstructure of MTA and Aureoseal Plus: XRF, EDS, XRD and FESEM evaluation.

PubMed

Cianconi, L; Palopoli, P; Campanella, V; Mancini, M

2016-12-01

The aim of this study was to determine the chemical composition and the phases' microstructure of Aureoseal Plus (OGNA, Italy) and ProRoot MTA (Dentsply Tulsa Dental, USA) and to compare their characteristics. Study Design: Comparing Aureoseal Plus and ProRoot MTA microstructure by means of several analyses type. The chemical analysis of the two cements was assessed following the UNI EN ISO 196-2 norm. X-Ray fluorescence (XRF) was used to determine the element composition. The crystalline structure was analysed quantitatively using x-ray diffraction (XRD). Powders morphology was evaluated using a scanning electron microscope (SEM) with backscattering detectors, and a field emission scanning electron microscope (FESEM). Elemental analysis was performed by energy dispersive x-ray analysis (EDS). The semi-quantitative XRF analysis showed the presence of heavy metal oxides in both cements. The XRD spectra of the two cements reported the presence of dicalcium silicate, tricalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, bismuth oxide and gypsum. SEM analysis showed that ProRoot MTA powder is less coarse and more homogeneous than Aureoseal. Both powders are formed by particles of different shapes: round, prismatic and oblong. The EDS analysis showed that some ProRoot MTA particles, differently from Aureoseal, contain Ca, Si, Al and Fe. Oblong particles in ProRoot and Aureoseal are rich of bismuth. The strong interest in developing new Portland cement-based endodontic sealers will create materials with increased handling characteristics and physicochemical properties. A thorough investigation on two cement powders was carried out by using XRF, XRD, SEM and EDS analysis. To date there was a lack of studies on Aureoseal Plus. This cement is similar in composition to ProRoot MTA. Despite that it has distinctive elements that could improve its characteristics, resulting in a good alternative to MTA.

The corrosion resistance of Wiron(®)88 in the presence of S. mutans and S. sobrinus bacteria.

PubMed

Proença, L; Barroso, H; Figueiredo, N; Lino, A R; Capelo, S; Fonseca, I T E

2015-01-01

The corrosion resistance of Wiron(®)88, a Ni-Cr-Mo alloy, was evaluated in liquid growth media in the absence and presence of the Streptococcus sobrinus and Streptococcus mutans strains. Open circuit potential measurements, cyclic voltammetry, linear sweep voltammetry, as well as electronic microscopy coupled to electron diffraction spectroscopy (SEM/EDS), were the main techniques used in this study. It was concluded that the presence of S. sobrinus and S. mutans have only a slight effect on the corrosion resistance of the Wiron(®)88 alloy, with the S. mutans being slightly more aggressive. For both strains the corrosion resistance R p is of the same order (kΩ cm(2)). After 24 h immersion the S. sobrinus lead to and R p of 11.02, while the S. mutans lead to of 5.59 kΩ cm(2). SEM/EDS studies on the Wiron(®)88 samples, with 24 days of immersion, at 37 °C, have confirmed bio-corrosion of the alloy occurring through the dissolution of Ni as Ni(2+) and formation of chromium and molybdenum oxides. The bacterial adhesion to the surface is not uniform.

Synthesis, Optical and Structural Properties of Copper Sulfide Nanocrystals from Single Molecule Precursors

PubMed Central

Ajibade, Peter A.; Botha, Nandipha L.

2017-01-01

We report the synthesis and structural studies of copper sulfide nanocrystals from copper (II) dithiocarbamate single molecule precursors. The precursors were thermolysed in hexadecylamine (HDA) to prepare HDA-capped CuS nanocrystals. The optical properties of the nanocrystals studied using UV–visible and photoluminescence spectroscopy showed absorption band edges at 287 nm that are blue shifted, and the photoluminescence spectra show emission curves that are red-shifted with respect to the absorption band edges. These shifts are as a result of the small crystallite sizes of the nanoparticles leading to quantum size effects. The structural studies were carried out using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy. The XRD patterns indicates that the CuS nanocrystals are in hexagonal covellite crystalline phases with estimated particles sizes of 17.3–18.6 nm. The TEM images showed particles with almost spherical or rod shapes, with average crystallite sizes of 3–9.8 nm. SEM images showed morphology with ball-like microspheres on the surfaces, and EDS spectra confirmed the presence of CuS nanoparticles. PMID:28336865

Additive assisted hydrothermal synthesis, characterization and optical properties of one dimensional DyPO4:Ce3+ nanostructures

NASA Astrophysics Data System (ADS)

Khajuria, H.; Kumar, M.; Singh, R.; Ladol, J.; Nawaz Sheikh, H.

2018-05-01

One dimensional nanostructures of cerium doped dysprosium phosphate (DyPO4:Ce3+) were synthesized via hydrothermal route in the presence of different surfactants [sodium dodecyl sulfate (SDS), dodecyl sulfosuccinate (DSS), polyvinyl pyrollidone (PVP)] and solvent [ethylene glycol and water]. The prepared nanostructures were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-VIS-NIR absorption spectrophotometer and photoluminescence (PL) studies. The PXRD and FTIR results indicate purity, good crystallinity and effective doping of Ce3+ in nanostructures. SEM and TEM micrographs display nanorods, nanowires and nanobundles like morphology of DyPO4:Ce3+. Energy-dispersive X-ray spectra (EDS) of DyPO4:Ce3+nanostructures confirm the presence of dopant. UV-VIS-NIR absorption spectra of prepared compounds are used to calculate band gap and explore their optical properties. Luminescent properties of DyPO4:Ce3+ was studied by using PL emission spectra. The effect of additives and solvents on the uniformity, morphology and optical properties of the nanostructures were studied in detail.

Green synthesis and characterization of graphene nanosheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavakoli, Farnosh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir; Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran

Highlights: • For the first time, we have synthesized graphene nanosheets in the presence of pomegranate juice. • Here pomegranate juice was used not only as reductant but also as capping agent. • FT-IR, XRD, SEM, EDS and TEM were used to characterize the samples. • According to TEM image, graphene nanosheet is individually exfoliated after stirring for 24 h. • As shown in the TEM image, graphene monolayer is obtained. - Abstract: For the first time, we have successfully synthesized graphene nanosheets in the presence of pomegranate juice. In this approach, pomegranate juice was used not only as reductantmore » but also as capping agent to form graphene nanosheets. At first, the improved Hummer method to oxidize graphite for the synthesis of graphene oxide (GO) was applied, and then the as-produced graphene oxide was reduced by pomegranate juice to form graphene nanosheets. Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and raman were used to characterize the samples. The results obtained from the characterization techniques proved high purity of the final products.« less

Anodic Aluminum Oxide Membrane-Assisted Fabrication of beta-In(2)S(3) Nanowires.

PubMed

Shi, Jen-Bin; Chen, Chih-Jung; Lin, Ya-Ting; Hsu, Wen-Chia; Chen, Yu-Cheng; Wu, Po-Feng

2009-06-06

In this study, beta-In(2)S(3) nanowires were first synthesized by sulfurizing the pure Indium (In) nanowires in an AAO membrane. As FE-SEM results, beta-In(2)S(3) nanowires are highly ordered, arranged tightly corresponding to the high porosity of the AAO membrane used. The diameter of the beta-In(2)S(3) nanowires is about 60 nm with the length of about 6-8 mum. Moreover, the aspect ratio of beta-In(2)S(3) nanowires is up to 117. An EDS analysis revealed the beta-In(2)S(3) nanowires with an atomic ratio of nearly S/In = 1.5. X-ray diffraction and corresponding selected area electron diffraction patterns demonstrated that the beta-In(2)S(3) nanowire is tetragonal polycrystalline. The direct band gap energy (E(g)) is 2.40 eV from the optical measurement, and it is reasonable with literature.

Novel mesoporous FeAl bimetal oxides for As(III) removal: Performance and mechanism.

PubMed

Ding, Zecong; Fu, Fenglian; Cheng, Zihang; Lu, Jianwei; Tang, Bing

2017-02-01

In this study, novel mesoporous FeAl bimetal oxides were successfully synthesized, characterized, and employed for As(III) removal. Batch experiments were conducted to investigate the effects of Fe/Al molar ratio, dosage, and initial solution pH values on As(III) removal. The results showed that the FeAl bimetal oxide with Fe/Al molar ratio 4:1 (shorten as FeAl-4) can quickly remove As(III) from aqueous solution in a wide pH range. The FeAl-4 before and after reaction with As(III) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED), Brunauer-Emmett-Teller (BET) surface area measurement, and X-ray photoelectron spectroscopy (XPS). The BET results showed that the original FeAl-4 with a high surface area of 223.9 m 2 /g was a mesoporous material. XPS analysis indicated that the surface of FeAl-4 possessed a high concentration of M-OH (where M represents Fe and Al), which was beneficial to the immobility of As(III). The excellent performance of FeAl-4 makes it a potentially attractive material for As(III) removal from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atomic-Scale Characterization of Oxide Interfaces and Superlattices Using Scanning Transmission Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spurgeon, Steven R.; Chambers, Scott A.

Scanning transmission electron microscopy (STEM) has become one of the fundamental tools to characterize oxide interfaces and superlattices. Atomic-scale structure, chemistry, and composition mapping can now be conducted on a wide variety of materials systems thanks to the development of aberration-correctors and advanced detectors. STEM imaging and diffraction, coupled with electron energy loss (EELS) and energy-dispersive X-ray (EDS) spectroscopies, offer unparalleled, high-resolution analysis of structure-property relationships. In this chapter we highlight investigations into key phenomena, including interfacial conductivity in oxide superlattices, charge screening effects in magnetoelectric heterostructures, the design of high-quality iron oxide interfaces, and the complex physics governing atomic-scalemore » chemical mapping. These studies illustrate how unique insights from STEM characterization can be integrated with other techniques and first-principles calculations to develop better models for the behavior of functional oxides.« less

Characterization and electron-energy-loss spectroscopy on NiV and NiMo superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahmood, S.H.

1986-01-01

NiV superlattices with periods (A) ranging from 15 to 80 A, and NiMo superlattices with from 14 to 110 A were studied using X-ray Diffraction (XRD), Electron Diffraction (ED), Energy-Dispersive X-Ray (EDX) microanalysis, and Electron Energy Loss Spectroscopy (EELS). Both of these systems have sharp superlattice-to-amorphous (S-A) transitions at about empty set = 17A. Superlattices with empty set around the S-A boundary were found to have large local variations in the in-plane grain sizes. Except for a few isolated regions, the chemical composition of the samples were found to be uniform. In samples prepared at Argonne National Laboratory (ANL), mostmore » places studied with EELS showed changes in the EELS spectrum with decreasing empty set. An observed growth in a plasmon peak at approx. 10ev in both NiV and NiMo as empty set decreased down to 19 A is attributed to excitation of interface plasmons. Consistent with this attribution, the peak height shrank in the amorphous samples. The width of this peak is consistent with the theory. The sift in this peak down to 9 ev with decreasing empty set in NiMo is not understood.« less

Green synthesis and characterization of Carica papaya leaf extract coated silver nanoparticles through X-ray diffraction, electron microscopy and evaluation of bactericidal properties

PubMed Central

Banala, Rajkiran Reddy; Nagati, Veera Babu; Karnati, Pratap Reddy

2015-01-01

The evolution of nanotechnology and the production of nanomedicine from various sources had proven to be of intense value in the field of biomedicine. The smaller size of nanoparticles is gaining importance in research for the treatment of various diseases. Moreover the production of nanoparticles is eco-friendly and cost effective. In the present study silver nanoparticles were synthesized from Carica papaya leaf extract (CPL) and characterized for their size and shape using scanning electron microscopy and transmission electron microscopy, respectively. Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDS/EDX) and X-ray diffraction spectroscopy (XRD) were conducted to determine the concentration of metal ions, the shape of molecules. The bactericidal activity was evaluated using Luria Bertani broth cultures and the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were estimated using turbidimetry. The data analysis showed size of 50–250 nm spherical shaped nanoparticles. The turbidimetry analysis showed MIC and MBC was >25 μg/mL against both Gram positive and Gram negative bacteria in Luria Bertani broth cultures. In summary the synthesized silver nanoparticles from CPL showed acceptable size and shape of nanoparticles and effective bactericidal activity. PMID:26288570

Green synthesis and characterization of Carica papaya leaf extract coated silver nanoparticles through X-ray diffraction, electron microscopy and evaluation of bactericidal properties.

PubMed

Banala, Rajkiran Reddy; Nagati, Veera Babu; Karnati, Pratap Reddy

2015-09-01

The evolution of nanotechnology and the production of nanomedicine from various sources had proven to be of intense value in the field of biomedicine. The smaller size of nanoparticles is gaining importance in research for the treatment of various diseases. Moreover the production of nanoparticles is eco-friendly and cost effective. In the present study silver nanoparticles were synthesized from Carica papaya leaf extract (CPL) and characterized for their size and shape using scanning electron microscopy and transmission electron microscopy, respectively. Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray spectroscopy (EDS/EDX) and X-ray diffraction spectroscopy (XRD) were conducted to determine the concentration of metal ions, the shape of molecules. The bactericidal activity was evaluated using Luria Bertani broth cultures and the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) were estimated using turbidimetry. The data analysis showed size of 50-250 nm spherical shaped nanoparticles. The turbidimetry analysis showed MIC and MBC was >25 μg/mL against both Gram positive and Gram negative bacteria in Luria Bertani broth cultures. In summary the synthesized silver nanoparticles from CPL showed acceptable size and shape of nanoparticles and effective bactericidal activity.

Piper betle-mediated synthesis, characterization, antibacterial and rat splenocyte cytotoxic effects of copper oxide nanoparticles.

PubMed

Praburaman, Loganathan; Jang, Jum-Suk; Muthusamy, Govarthanan; Arumugam, Sengottaiyan; Manoharan, Koildhasan; Cho, Kwang-Min; Min, Cho; Kamala-Kannan, Seralathan; Byung-Taek, Oh

2016-09-01

The study reports a simple, inexpensive, and eco-friendly synthesis of copper oxide nanoparticles (CuONPs) using Piper betle leaf extract. Formation of CuONPs was confirmed by UV-visible spectroscopy at 280 nm. Transmission electron microscopy (TEM) images showed that the CuONPs were spherical, with an average size of 50-100 nm. The scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) peak was observed approximately at 1 and 8 keV. The X-ray diffraction (XRD) studies indicated that the particles were crystalline in nature. CuONPs effectively inhibited the growth of phytopathogens Ralstonia solanacearum and Xanthomonas axonopodis. The cytotoxic effect of the synthesized CuONPs was analyzed using rat splenocytes. The cell viability was decreased to 94% at 300 μg/mL.

Room temperature ferromagnetism in Mg-doped ZnO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jaspal, E-mail: jaspal0314@gmail.com; Vashihth, A.; Gill, Pritampal Singh

Zn{sub 1-x}Mg{sub x}O (x = 0, 0,10) nanoparticles were successfully synthesized using sol-gel method. X-ray diffraction (XRD) confirms that the synthesized nanoparticles possess wurtzite phase having hexagonal structure. Morphological analysis was carried out using transmission electron microscopy (TEM) which depicts the spherical morphology of ZnO nanoparticles. Energy dispersive spectroscopy (EDS) showed the presence of Mg in ZnO nanoparticles. Electron spin resonance (ESR) signal was found to be decreasing with increasing of Mg-doping concentration. The room temperature ferromagnetism was observed in undoped and Mg-doped ZnO nanoparticles. The increase of Mg-doping concentration resulted in decrease of saturation magnetization value which could bemore » attributed to decrease of oxygen vacancies present in host nanoparticles.« less

Anti-bacteria activity of carbon nanotubes grown on trimetallic catalyst

NASA Astrophysics Data System (ADS)

Ibrahim, S. O.; Abdulkareem, A. S.; Isah, K. U.; Ahmadu, U.; Bankole, M. T.; Kariim, I.

2018-06-01

Trimetallic catalyst was prepared using wet impregnation method to produce carbon nanotubes (CNTs) through the method of catalytic chemical vapor deposition (CCVD). Characterization of the developed catalyst and CNTs were carried out using thermogravimetric analysis (TGA), x-ray diffraction (XRD), specific surface area Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HRSEM)/energy dispersive x-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HRTEM)/selected area electron diffraction (SAED). The BET and TGA analysis indicated that the catalyst has a high surface area and is thermally stable. The FTIR of the developed catalyst shows notable functional group with presence of unbound water. The HRSEM of the catalyst revealed agglomerated, homogeneous and porous particles while the HRSEM/HRTEM of the produced CNTs gave the formation of long strand of multiwalled carbon nanotubes (MWCNTs), and homogeneous crystalline fringe like structure with irregular diameter. EDS revealed the dominance of carbon in the elemental composition. XRD/SAED patterns of the catalyst suggest high dispersion of the metallic particles in the catalyst mixture while that of the CNTs confirmed that the produced MWCNTs were highly graphitized and crystalline in nature with little structural defects. The anti-bacteria activity of the produced MWCNTs on Klebsiella pneumoneae, Escherichia coli, and Pseudomonas aeruginosa was also carried out. It was observed that the produced MWCNTs have an inhibitory property on bacteria; Escherichia coli and Klebsiella pneumoneae from zero day ( and ) through to twelfth day (Nil count) respectively. It has no effect on Pseudomonas aeruginosa with too numerous to count at zero-sixth day, but a breakdown in its growth at ninth-twelfth day (). This study implied that MWCNTs with varying diameter and well-ordered nano-structure can be produced from catalyst via CCVD method, and it can be recommended that the MWCNTs can be used to treat infected media contaminated with Klebsiella pneumoneae, Escherichia coli, and Pseudomonas aeruginosa.

Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solehudin, Agus, E-mail: asolehudin@upi.edu; Nurdin, Isdiriayani

2014-03-24

Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H{sub 2}S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAHmore » concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.« less

Nanoparticulate mineral matter from basalt dust wastes.

PubMed

Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

2016-02-01

Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Conservation of Moroccan manuscript papers aged 150, 200 and 800 years. Analysis by infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and scanning electron microscopy energy dispersive spectrometry (SEM-EDS).

PubMed

Hajji, Latifa; Boukir, Abdellatif; Assouik, Jamal; Lakhiari, Hamid; Kerbal, Abdelali; Doumenq, Pierre; Mille, Gilbert; De Carvalho, Maria Luisa

2015-02-05

The preservation of manuscripts and archive materials is a serious problem for librarians and restorers. Paper manuscript is subjected to numerous degradation factors affecting their conservation state. This research represents an attempt to evaluate the conservation restoration process applied in Moroccan libraries, especially the alkaline treatment for strengthening weakened paper. In this study, we focused on six samples of degraded and restored paper taken from three different Moroccan manuscripts aged 150, 200 and 800 years. In addition, the Japanese paper used in restoration has been characterized. A modern paper was also analyzed as reference. A three-step analytical methodology based on infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and scanning electron microscopy coupled to energy dispersive spectrometry (SEM-EDS) analysis was developed before and after restoration in order to determine the effect of the consolidation treatment on the paper structure. The results obtained by XRD and ATR-FTIR disclosed the presence of barium sulfate (BaSO4) in all restored paper manuscripts. The presence of calcium carbonate (CaCO3) in all considered samples was confirmed by FTIR spectroscopy. The application of de-acidification treatment causes significant changes connected with the increase of intensity mostly in the region 1426 cm(-1), assigned to the asymmetric and symmetric CO stretching mode of calcite, indicating the effectiveness of de-acidification procedure proved by the rise of the alkaline reserve content allowing the long term preservation of paper. Observations performed by SEM magnify the typical paper morphology and the structure of fibbers, highlighting the effect of the restoration process, manifested by the reduction of impurities. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal evaporation and condensation synthesis of metallic Zn layered polyhedral microparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Waheed S.; Cao, Chuanbao, E-mail: cbcao@bit.edu.cn; Usman, Zahid

2011-12-15

Highlights: Black-Right-Pointing-Pointer Zn polyhedral microparticles prepared by thermal evaporation and condensation route. Black-Right-Pointing-Pointer Vapour-solid process based growth model governs the formation of Zn microparticles. Black-Right-Pointing-Pointer A strong PL emission band is observed at 369 nm in UV region. Black-Right-Pointing-Pointer Radiative recombination of electrons in the s, p conduction band and the holes in the d bands causes this emission. -- Abstract: Metallic zinc layered polyhedral microparticles have been fabricated by thermal evaporation and condensation technique using zinc as precursor at 750 Degree-Sign C for 120 min and NH{sub 3} as a carrier gas. The zinc polyhedral microparticles with oblate sphericalmore » shape are observed to be 2-9 {mu}m in diameter along major axes and 1-7 {mu}m in thickness along minor axes. The structural, compositional and morphological characterizations were performed by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). A vapour-solid (VS) mechanism based growth model has been proposed for the formation of Zn microparticles. Room temperature photoluminescence (PL) emission spectrum of the product exhibited a strong emission band at 369 nm attributed to the radiative recombination of electrons in the s, p conduction band near Fermi surface and the holes in the d bands generated by the optical excitation.« less

Investigation of Zn2+ and Cd2+ Adsorption Performanceby Different Weathering Basalts

NASA Astrophysics Data System (ADS)

Xue, Q.; Shuo, Q.; Chen, H.

2016-12-01

Geological barriers play an important role in preventing pollution of groundwater. Basalts are common geological media; however, there have not been any studies that report the effect of basalt type on the metal ion adsorption performance. In this study, we explored the metal ion (Zn2+ and Cd2+) adsorption ability of two kinds of weathering basalts: the origin weathering basalt (WB) and the eluvial deposit (ED), both of which were derived from same basaltic formation. Characteristics of the sediments were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Barrett-Joyner-Halenda (BJH) measurement and the rapid potentiometric titration (RPT) method. Batch experiments were performed to evaluate the Zn2+ and Cd2+ adsorption performance of WB and ED and how adsorption was affected by contact time, initial metal ion concentration, pH and ionic strength. Despite WB and ED having similar chemical compositions, WB exhibited better adsorption than ED likely due to the fact that WB was rougher and had more small-sized spherical structures and stronger electrostatic forces. The adsorption process fit the Freundlich isotherm model well. The adsorption efficiency decreased with a decrease of pH (from 4 to 2) and with increasing ionic strength. These results suggest that a geological barrier composed of WB media might be able to effectively sequester metallic contaminants to prevent them from reaching groundwater.

Data on Molluscan Shells in parts of Nellore Coast, southeast coast of India.

PubMed

Lakshmanna, B; Jayaraju, N; Prasad, T Lakshmi; Sreenivasulu, G; Nagalakshmi, K; Kumar, M Pramod; Madakka, M

2018-02-01

X-ray diffraction (XRD), Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS), and Fourier Transform Infrared Spectroscopy (FT-IR), were applied to analyze the organic matrix of two Molluscan shells . The Mollusca shells are mineral structure and calcium carbonate crystallized as aragonite. The FT-IR spectra showed Alkyl Halide, Alkanes, Alcohols, Amides, Aromatic, and Hydroxyl groups in the organic matrix of the whole (organic and mineral) Molluscan shells. SEM images of particles of the two Molluscan shells at different magnifications were taken. The morphologies of the samples show a flake like structures with irregular grains, their sizes are at micrometric scale and the chemical analysis of EDS indicated that the major elements of Cardita and Gastropoda were C, O, and Ca, consistent with the results of XRD analysis. The results of the analysis of the EDS spectra of the shells showed that the content of most of the powder composition of shells is the element carbon, calcium oxygen, aluminium, and lead peaks that appear on the Cardita and Gastropoda and shells powders tap EDS spectra. The present work examined organic matrix of the selected shells of the heavily polluted and light polluted sites, along Nellore Coast, South East Coast of India. The heavily polluted sites have significantly thickened shells. The data demonstrated the sensitivity of this abundant and widely distributed intertidal fragile environment.

Structural analysis of aluminium substituted nickel ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Singh, H. S.; Sangwa, Neha

2018-05-01

Aluminium substituted nickel ferrite nanoparticles were synthesized by High Energy Ball milling (HEBM) of the mixture of α-NiO, α-Al2O3 and α-Fe2O3 followed by annealing at 1000˚C. X-ray diffraction (XRD) and Energy dispersive spectroscopy analysis (EDS) characterization was done for Aluminium substituted nickel ferrite. The structural analysis reveals the formation of the single phase compound. The average grain size was estimated by X-ray diffraction technique ranges from 30 to 10 nm with the increasing concentration of Aluminium. EDS spectra conforms the homogeneous mixing and purity of ferrite.

Synthesis and characterization of NiO nanopowder by sol-gel process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ningsih, Sherly Kasuma Warda

2015-09-30

Preparation of nickel oxide (NiO) nanopowder by sol-gel process has been studied. NiO nanopowders were obtained by sol-gel method by using nickel nitrate hexahydrate and sodium hydroxide and aquadest were used as precursor, agent precipitator and solvent, respectively. The powders were formed by drying at 110°C and followed by heating in the furnace at 400°C for 1.5 hours. The product was obtained black powder. The product was characterized by Energy Dispesive X-ray Fluorescence (ED-XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The ED-XRF pattern shows the composition of NiO produced was 97.1%. The XRD pattern showed NiO forms weremore » produced generally in monoclinic stucture. The crystalline size of NiO was obtained in the range 40-85 nm. SEM micrograph clearly showed that powder had a spherical with uniform distribution size is 0.1-1.0 µm approximately.« less

Characterization of Thin Walled Mo Tubing produced by FBCVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beaux, Miles Frank; Usov, Igor Olegovich

2016-01-21

The goal of this report is to delineate the results of material characterization performed on Mo tubing produced via the fluidized bed chemical vapor deposition (FBCVD) method. Scanning electron microscopy (SEM) imaging reveals that small randomly oriented grains are achieved in the Mo deposition, but do not persist throughout the entire thickness of the material. Energy dispersive spectroscopy (EDS) reveals the Mo tubes contain residual chlorine and oxygen. EDS measurements on the tube surfaces separated from glass and quartz substrates reveal substrate material adhered to this surface. X-ray diffraction (XRD) revealed the presence of carbon contaminant in the form ofmore » Mo 2C and oxygen in the form of MoO 2. Combustion infrared detection (CID) and inert gas fusion (IGF) performed at Luvak Inc. was used to quantify weight percentages of oxygen and carbon in the tubes produced. Hardness value of the FBCVD Mo was found to be comparable to low carbon arc cast molybdenum.« less

Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayachandraiah, C.; Kumar, K. Siva; Krishnaiah, G., E-mail: ginnerik@gmail.com

2015-06-24

Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PLmore » studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.« less

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

2016-01-01

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

Structural and electrical properties of Li4Ti5O12 anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Vikram Babu, B.; Vijaya Babu, K.; Tewodros Aregai, G.; Seeta Devi, L.; Madhavi Latha, B.; Sushma Reddi, M.; Samatha, K.; Veeraiah, V.

2018-06-01

In this work we investigate Li4Ti5O12 (LTO) anode material synthesized by conventional solid state reaction method calcined at 850 °C for 16 h. Thermal analysis reveals the temperature dependence of the material properties. The phase composition, micro-morphology and elemental analysis of the compound are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectra (EDS) respectively. The results of XRD pattern possessed cubic spinel structure with space group Fd-3m. The morphological features of the powder sample are in the range of 1.1 μm. The EDS spectra confirm the constituent elemental composition of the sample. Electrical conductivity measurement at different frequencies and temperatures had been carried out; and at room temperature it is found to be 5.96 × 10-7 S/cm. Besides, for the different frequencies applied, the activation energies were calculated and obtained to be in the range of 0.2-0.4 eV.

Picosecond laser fabricated Ag, Au and Ag-Au nanoparticles for detecting ammonium perchlorate using a portable Raman spectrometer

NASA Astrophysics Data System (ADS)

Byram, Chandu; Moram, Sree Sathya Bharathi; Soma, Venugopal Rao

2018-04-01

In this paper, we present the results from fabrication studies of Ag, Au, and Ag-Au alloy nanoparticles (NPs) using picosecond laser ablation technique in the presence of liquid media. The alloy formation in the NPs was confirmed from UV-Visible measurements. The shape and crystallinity of NPs were investigated by using high resolution transmission electron microscopy (HRTEM), selected area diffraction pattern (SAED) and energy dispersive spectroscopy (EDS). The SERS effect of fabricated NPs was tested with methylene blue and an explosive molecule (ammonium perchlorate) using a portable Raman spectrometer and achieved EFs of ˜106.

Surface modification of hydroturbine steel using friction stir processing

NASA Astrophysics Data System (ADS)

Grewal, H. S.; Arora, H. S.; Singh, H.; Agrawal, A.

2013-03-01

Friction stir processing (FSP) has proved to be a viable tool for enhancing the mechanical properties of materials, however, the major focus has been upon improving the bulk properties of light metals and their alloys. Hydroturbines are susceptible to damage owing to slurry and cavitation erosion. In this study, FSP of a commonly employed hydroturbine steel, 13Cr4Ni was undertaken. Microstructural characterization of the processed steel was conducted using optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) techniques. Mechanical characterization of the steel was undertaken in terms of microhardness and resistance to cavitation erosion (CE). FSP resulted in the refinement of the microstructure with reduction in grain size by a factor of 10. EBSD results confirmed the existence of submicron and ultrafine grained microstructure. The microhardness of the steel was found to enhance by 2.6 times after processing. The processed steel also showed 2.4 times higher resistance against cavitation erosion in comparison to unprocessed steel. The primary erosion mechanism for both the steels was identical in nature, with plastic deformation responsible for the loss of material.

Crystal Structure, Magnetic and Optical Properties of Mn-Doped BiFeO₃ by Hydrothermal Synthesis.

PubMed

Zhang, Ning; Wei, Qinhua; Qin, Laishun; Chen, Da; Chen, Zhi; Niu, Feng; Wang, Jiangying; Huanag, Yuexiang

2017-01-01

In this paper, Mn doped BiFeO₃ were firstly synthesized by hydrothermal process. The influence of Mn doping on structural, optical and magnetic properties of BiFeO₃ was studied. The different amounts of Mn doping in BiFeO₃ were characterized by X-ray diffraction, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscope, UV-Vis diffuse reflectance spectroscopy and magnetic measurements. The X-ray diffraction (XRD) patterns confirmed the formation of pure phase rhombohedral structure in BiFe(1−x) Mn (x) O₃ (x = 0.01, 0.03, 0.05, 0.07) samples. The morphologies and chemical compositions of as-prepared samples could be observed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscope (EDS). A relative large saturated magnetization (Ms) of 0.53 emu/g for x = 0.07 sample was obtained at room temperature, which is considered to be Mn ions doping. UV-Vis diffuse reflectance spectroscopy showed strong absorption of light in the range of 200–1000 nm, indicating the optical band gap in the visible region for these samples. This implied that BiFe(1−x) Mn(x)O₃ may be a potential photocatalyst for utilizing solar energy.

Phase behavior and transitions of self-assembling nano-structured materials

NASA Astrophysics Data System (ADS)

Duan, Hu

Homologous series of supramolecular nanostructures have been investigated by a combination of transmission electron microscopy (TEM), electron diffraction (ED), thermal polarized optical microscopy and X-ray diffraction (XRD). Materials include amphiphilic oligomers and polymer such as charged complexes, dipeptide dendrons semi-fluorinated dendron and polyethyleneimines. Upon microphase separation, they self-assemble into either cylindrical or spherical shapes, which co-organize into a 2D P6mm hexagonal columnar phase or 3D Pm 3¯ n and Im 3¯ m cubic phases. Correlation between the phase selection and molecular architecture is established accordingly. The order-disorder transition (ODT) is explored by rheometry and rheo-optical microscopy in a model polymeric compound poly(N-[3,4-bis(n-dodecan-1-yloxy)benzoyl]ethyleneimine). Shear alignment of the hexagonal columnar liquid crystalline phase along the velocity direction at low temperature and shear disordering in the vicinity of the ODT were observed. After cessation of shear, transformation back to the stable columnar phase follows a row-nucleation mechanism. The order-order transition process is explored in a monodendron that exhibits a hexagonal columnar and a weakly birefringent mesophase. Polarized DIC microscopy strongly supports an epitaxial relationship between them.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooke, Gary A.; Pestovich, John A.; Huber, Heinz J.

This report presents the results for solid phase characterization (SPC) of solid samples removed from tank 241-C-108 (C-108) on August 12-13,2012, using the off-riser sampler. Samples were received at the 222-S Laboratory on August 13 and were described and photographed. The SPC analyses that were performed include scanning electron microscopy (SEM) using the ASPEX(R)l scanning electron microscope, X-ray diffraction (XRD) using the Rigaku(R) 2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon(R) 3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information. Gary A. Cooke conducted themore » SEM analysis, John A. Pestovich performed the XRD analysis, and Dr. Heinz J. Huber performed the PLM examination. The results of these analyses are presented here.« less

Study of free radicals in gamma irradiated cellulose of cultural heritage materials using Electron Paramagnetic Resonance

NASA Astrophysics Data System (ADS)

Kodama, Yasko; Rodrigues, Orlando, Jr.; Garcia, Rafael Henrique Lazzari; Santos, Paulo de Souza; Vasquez, Pablo A. S.

2016-07-01

Main subject of this article was to study room temperature stable radicals in Co-60 gamma irradiated contemporary paper using Electron Paramagnetic Resonance spectrometer (EPR). XRD was used to study the effect of ionizing radiation on the morphology of book paper. SEM images presented regions with cellulose fibers and regions with particles agglomeration on the cellulose fibers. Those agglomerations were rich in calcium, observed by EDS. XRD analysis confirmed presence of calcium carbonate diffraction peaks. The main objective of this study was to propose a method using conventional kinetics chemical reactions for the observed radical formed by ionizing radiation. Therefore, further analyses were made to study the half-life and the kinetics of the free radical created. This method can be suitably applied to study radicals on cultural heritage objects.

Hydroxyapatite coatings produced on commercially pure titanium by micro-arc oxidation.

PubMed

Huang, Yong; Wang, Yingjun; Ning, Chengyun; Nan, Kaihui; Han, Yong

2007-09-01

A porous hydroxyapatite (HA) coating on commercially pure titanium was prepared by micro-arc oxidation (MAO) in electrolytic solution containing calcium acetate and beta-glycerol phosphate disodium salt pentahydrate (beta-GP). The thickness, phase, composition morphology and biocompatibility of the oxide coating were characterized by x-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM) with an energy dispersive x-ray spectrometer (EDS) and cell culture. The thickness of the MAO film was about 20 microm, and the coating was porous and uneven without any apparent interface to the titanium substrates. The result of XRD showed that the porous coating was made up of HA film. The favorable osteoblast cell affinity gives HA film good biocompatibility. HA coatings are expected to have significant uses for medical applications such as dental implants and artificial bone joints.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi, Gaosong; Cullen, David A.; Littrell, Kenneth C.

For this research, long-term aged [343 K (70 °C) for 30 months and natural exposure for over 10 years] Al 5456 H116 samples were characterized using electron backscatter diffraction (EBSD), scanning transmission electron microscopy (STEM), state-of-the-art energy-dispersive X-ray spectroscopy (EDS) systems, and small-angle neutron scattering (SANS). ASTM G-67 mass loss tests of the sensitized Al 5456 alloy samples were conducted. Intragranular Mg-rich precipitates, such as Guinier–Preston (GP) zones, were confirmed in Al 5456 H116 aged at 343 K (70 °C) for 30 months, and the volume of these precipitates is 1.39 pct. β' phase is identified at the grain boundarymore » of a navy ship sample, while high-resolution STEM results reveal no intragranular precipitates. Intergranular corrosion (IGC) of Al 5456 was found to be related to the continuity of intergranular precipitates.« less

TEM Analysis of Diffusion-Bonded Silicon Carbide Ceramics Joined Using Metallic Interlayers

NASA Technical Reports Server (NTRS)

Ozaki, T.; Hasegawa, Y.; Tsuda, H.; Mori, S.; Halbig, M. C.; Asthana, R.; Singh, M.

2017-01-01

SiC fiber-bonded ceramics (SA-Tyrannohex: SA-THX) diffusion-bonded with TiCu metallic interlayers were investigated. Thin samples of the ceramics were prepared with a focused ion beam (FIB) and the interfacial microstructure of the prepared samples was studied by transmission electron microscopy (TEM) and scanning TEM (STEM). In addition to conventional microstructure observation, for detailed analysis of reaction compounds in diffusion-bonded area, we performed STEM-EDS measurements and selected area electron diffraction (SAD) experiments. The TEM and STEM experiments revealed the diffusion-bonded area was composed of only one reaction layer, which was characterized by TiC precipitates in Cu-Si compound matrix. This reaction layer was in good contact with the SA-THX substrates, and it is concluded that the joint structure led to the excellent bonding strength.

Size and morphology controlled NiSe nanoparticles as efficient catalyst for the reduction reactions

NASA Astrophysics Data System (ADS)

Subbarao, Udumula; Marakatti, Vijaykumar S.; Amshumali, Mungalimane K.; Loukya, B.; Singh, Dheeraj Kumar; Datta, Ranjan; Peter, Sebastian C.

2016-12-01

Facile and efficient ball milling and polyol methods were employed for the synthesis of nickel selenide (NiSe) nanoparticle. The particle size of the NiSe nanoparticle has been controlled mechanically by varying the ball size in the milling process. The role of the surfactants in the formation of various morphologies was studied. The compounds were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The efficiency of the NiSe nanoparticle as a catalyst was tested for the reduction of para-nitroaniline (PNA) to para-phenyldiamine (PPD) and para-nitrophenol (PNP) to para-aminophenol (PAP) using NaBH4 as the reducing agent. Particle size, morphology and the presence of surfactant played a crucial role in the reduction process.

Decorating multi-walled carbon nanotubes with quantum dots for construction of multi-color fluorescent nanoprobes.

PubMed

Jia, Nengqin; Lian, Qiong; Tian, Zhong; Duan, Xin; Yin, Min; Jing, Lihong; Chen, Shouhui; Shen, Hebai; Gao, Mingyuan

2010-01-29

Novel multi-color fluorescent nanoprobes were prepared by electrostatically assembling differently sized CdTe quantum dots on polyethylenimine (PEI) functionalized multi-walled carbon nanotubes (MWNTs). The structural and optical properties of the nano-assemblies (MWNTs-PEI-CdTe) were characterized by transmission electron microscopy (TEM), electron diffraction spectra (EDS), Raman spectroscopy, confocal microscopy and photoluminescence spectroscopy (PL), respectively. Electrochemical impedance spectroscopy (EIS) was also applied to investigate the electrostatic assembling among oxidized MWNTs, PEI and CdTe. Furthermore, confocal fluorescence microscopy was used to monitor the nano-assemblies' delivery into tumor cells. It was found that the nano-assemblies exhibit efficient intracellular transporting and strong intracellular tracking. These properties would make this luminescent nano-assembly an excellent building block for the construction of intracellular nanoprobes, which could hold great promise for biomedical applications.

Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents

NASA Astrophysics Data System (ADS)

Arulmozhi, K. T.; Mythili, N.

2013-12-01

Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

Effective reduction of p-nitrophenol by silver nanoparticle loaded on magnetic Fe3O4/ATO nano-composite

NASA Astrophysics Data System (ADS)

Karki, Hem Prakash; Ojha, Devi Prashad; Joshi, Mahesh Kumar; Kim, Han Joo

2018-03-01

A silver loaded hematite (Fe3O4) and antimony doped tin oxide (ATO) magnetic nano-composite (Ag-Fe3O4/ATO) was successfully synthesized by in situ one pot green and facile hydrothermal process. The formation of nano-composite, its structure, morphology, and stability were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), elemental mapping by high resolution scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red spectroscopy (FTIR). UV-vis spectroscopy was used to monitor the catalytic reduction of p-nitrophenol (PNP) into p-aminophenol (PAP) in presence of Ag-Fe3O4/ATO nano-composite with excess of sodium borohydride (NaBH4). The pseudo-first order kinetic equation could describe the reduction of p-nitrophenol with excess of NaBH4. For the first time, ATO surface was used for hydrothermal growth of silver and iron oxide magnetic nanoparticles. The in situ growth of these nanoparticles provided an effective bonding of components of the nano-composite over the surface of ATO nanoparticles. This nano-composite exhibited easy synthesis, high stability, cost effective and rapid separation using external magnet. The excellent catalytic and anti-bacterial activity of as-synthesized silver nano-composite makes it potential nano-catalyst for waste water treatment as well as biomedical application.

Shape-controlled synthesis and properties of dandelion-like manganese sulfide hollow spheres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Wei; State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083; Chen, Gen

2012-09-15

Graphical abstract: Dandelion-like MnS hollow spheres assembled with nanorods could be successfully synthesized in large quantities through a simple and convenient hydrothermal synthetic method under mild conditions using soluble hydrated manganese chloride as Mn source, L-cysteine as both a precipitator and complexing reagent. The dandelion-like MnS hollow spheres might have potential applications in microdevices and magnetic cells. Highlights: ► MnS hollow spheres assembled with nanorods could be synthesized. ► The morphologies and sizes of final products could be controlled. ► Possible formation mechanism of MnS hollow spheres is proposed. -- Abstract: Dandelion-like gamma-manganese (II) sulfide (MnS) hollow spheres assembled withmore » nanorods have been prepared via a hydrothermal process in the presence of L-cysteine and polyvinylpyrrolidone (PVP). L-cysteine was employed as not only sulfur source, but also coordinating reagent for the synthesis of dandelion-like MnS hollow spheres. The morphology, structure and properties of as-prepared products have been investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM) and photoluminescence spectra (PL). The probable formation mechanism of as-prepared MnS hollow spheres was discussed on the basis of the experimental results. This strategy may provide an effective method for the fabrication of other metal sulfides hollow spheres.« less

Surfactant-free bio-synthesised Tio2 nanorods from Turbinaria conoides-a study on photocatalytic and anti-bacterial activity

NASA Astrophysics Data System (ADS)

Subhapriya, S.; Gomathipriya, P.

2018-06-01

In this study, Titania nanorods were synthesised from aqueous extract of Turbinaria conoides (brown seaweeds) (TiO2NRs-TC) under surfactant free medium. The photocatalytic activity of the synthesised nanorods was tested towards the photocatalytic decolourization using simulated dye wastewater containing Navy Blue HER (NBHER). The synthesised Titania nanorods were characterized by using x-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrophotometer (EDS) and Transmission Electron Microscopy (TEM). XRD pattern confirms the anatase phase formation and HR-SEM micrograph shows the presence of rod like structure with the size of about 50 nm. TEM analysis proves the rod like structure with a size of 45–50 nm which was in agreement with the XRD analysis and HR-SEM images. EDS and XDS confirmed the formation of Titania nanoparticles. The formation of TiO2NRs-TC has a beneficial influence on the dye Navy blue HER photodegradation. TiO2-TC nano rods also show superior photocatalytic ability in hydrogen generation (2.1 mmol/h‑1g‑1). The antibacterial activity of the synthesised nanoparticles was examined using disc diffusion method which showed diverse susceptibility of microorganisms to the Titania nanoparticles.

Characterization of the effects of different tempers and aging temperatures on the precipitation behavior of Al-Mg (5.25at.%)-Mn alloys

DOE PAGES

Yi, Gaosong; Littrell, Kenneth C.; Poplawsky, Jonathan D.; ...

2017-01-11

We investigated the effects of different tempers (H131 and H116) and different aging temperatures (50 and 70 °C) on the precipitation behavior of Al-Mg (5.25 at.%)-Mn (Al 5083) alloys aged for a long time (41 and 30 months) using electron backscatter diffraction(EBSD), scanning transmission electron microscopy(STEM), energy-dispersive X-ray spectroscopy(EDS), atom probe tomography (APT), and small angle neutron scattering (SANS). Results for the GP zones and β'' phases were found in Al 5083 H116 aged at 50 °C for 24 months using APT. EDS and SANS revealed that a phase transformation process from GP zones to β'/β phases occurred for precipitatesmore » formed in both Al 5083 H131 and H116 aged at 70 °C. The effective diffusion coefficient of Mg in Al 5083 H131 is 1.8 times of that in Al 5083 H116 aged at 70 °C. The precipitation process in Al 5083 H116 aged at 50 °C is much slower than that in the sample aged at 70 °C. Finally, we identified the coarsening process in Al 5083 H131 and H116 aged at 70 °C for > 9 months.« less

Investigation of the Microstructure and Mechanical Properties of Copper-Graphite Composites Reinforced with Single-Crystal α-Al₂O₃ Fibres by Hot Isostatic Pressing.

PubMed

Zhang, Guihang; Jiang, Xiaosong; Qiao, ChangJun; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao; Valcarcel, Victor

2018-06-11

Single-crystal α-Al₂O₃ fibres can be utilized as a novel reinforcement in high-temperature composites owing to their high elastic modulus, chemical and thermal stability. Unlike non-oxide fibres and polycrystalline alumina fibres, high-temperature oxidation and polycrystalline particles boundary growth will not occur for single-crystal α-Al₂O₃ fibres. In this work, single-crystal α-Al₂O₃ whiskers and Al₂O₃ particles synergistic reinforced copper-graphite composites were fabricated by mechanical alloying and hot isostatic pressing techniques. The phase compositions, microstructures, and fracture morphologies of the composites were investigated using X-ray diffraction, a scanning electron microscope equipped with an X-ray energy-dispersive spectrometer (EDS), an electron probe microscopic analysis equipped with wavelength-dispersive spectrometer, and a transmission electron microscope equipped with EDS. The mechanical properties have been measured by a micro-hardness tester and electronic universal testing machine. The results show that the reinforcements were unevenly distributed in the matrix with the increase of their content and there were some micro-cracks located at the interface between the reinforcement and the matrix. With the increase of the Al₂O₃ whisker content, the compressive strength of the composites first increased and then decreased, while the hardness decreased. The fracture and strengthening mechanisms of the composite materials were explored on the basis of the structure and composition of the composites through the formation and function of the interface. The main strengthening mechanism in the composites was fine grain strengthening and solid solution strengthening. The fracture type of the composites was brittle fracture.

Synthesis and application of surfactants coated magnetite nanoparticles for demulsification of crude oil in water emulsion

NASA Astrophysics Data System (ADS)

Yau, Xin Hui; Khe, Cheng Seong; Liu, Wei Wen; Lai, Chin Wei; Oo, Zeya

2017-10-01

Magnetite nanoparticles were synthesized through co-precipitation method, in which surfactant such as polyvinylpyrrolidone (PVP) and sodium dodecyl benzene sulfonate (SDBS) were applied as stabilizing agent. Various techniques were employed to characterize the synthesized magnetite nanoparticles. Magnetite nanoparticles with spinel structure are successfully synthesized and confirmed by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results proved that surface of magnetite nanoparticles were successfully coated with PVP and SDBS. From the transmission electron microscope (TEM), it showed that surfactant coated magnetite nanoparticles possess smaller particle size than that of bare magnetite nanoparticles. In comparison with SDBS, PVP has a better capping efficiency and the PVP coated magnetite nanoparticles have an average particle size of 10.8 nm. In addition, surfactant coated magnetite nanoparticles also exhibited lower value of saturation magnetization (Ms). Lower value of Ms might be attributed to the small sized nanoparticles. All magnetite nanoparticles synthesized with and without surfactant showed superparamagnetic behaviour. Bare and surfactant coated magnetite nanoparticles have been utilized as a demulsifier for crude oil in water emulsion. Those nanoparticles that produced using SDBS (ED= 87%) showed higher efficiency than that of PVP coated (ED=80%) and bare magnetite nanoparticles (ED=85%) in demulsification tests.

Microstructural characterization of AA5183 aluminum clad AISI 1018 steel prepared by electro spark deposition

NASA Astrophysics Data System (ADS)

Rastkerdar, E.; Aghajani, H.; Kianvash, A.; Sorrell, C. C.

2018-04-01

The application of a simple and effective technique, electro spark deposition (ESD), to create aluminum clad steel plate has been studied. AA5183 aluminum rods were used as the rotating electrode for cladding of the AISI 1018 steel. The microstructure of the interfacial zone including the intermetallic compounds (IMC) layer and the clad metal have been investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM and STEM). According to the results sound aluminum clad with thickness up to 25–30 μm can be achieved. Very thin (<4 μm) IMC layer was formed at the Al/Fe interface and the structural (electron diffraction pattern) and chemical analysis (STEM) conducted by TEM confirmed that the layer is constituted of Fe rich phases, both implying a much improved mechanical properties. Investigation of the orientations of phases at the interfacial zone confirmed absence of any preferred orientation.

Synthesis of Al₂Ca Dispersoids by Powder Metallurgy Using a Mg-Al Alloy and CaO Particles.

PubMed

Fujita, Junji; Umeda, Junko; Kondoh, Katsuyoshi

2017-06-28

The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4.7-at % Al atoms formed a supersaturated solid solution in the α-Mg matrix. Transmission electron microscopy-EDS and X-ray diffraction analyses on the AZ61B composite precursor with 10-vol % CaO particles obtained by heat treatment confirmed that CaO additives were thermally decomposed in the Mg-Al alloy, and the solid-soluted Ca atoms diffused along the α-Mg grain boundaries. Al atoms also diffused to the grain boundaries because of attraction to the Ca atoms resulting from a strong reactivity between Al and Ca. As a result, needle-like (Mg,Al)₂Ca intermetallics were formed as intermediate precipitates in the initial reaction stage during the heat treatment. Finally, the precipitates were transformed into spherical Al₂Ca particles by the substitution of Al atoms for Mg atoms in (Mg,Al)₂Ca after a long heat treatment.

A comparative study of the effect of α-, β-, and γ-cyclodextrins as stabilizing agents in the synthesis of silver nanoparticles using a green chemistry method.

PubMed

Suárez-Cerda, Javier; Nuñez, Gabriel Alonso; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z

2014-10-01

This paper describes the effect of different types of cyclodextrins (CDs) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO3) with α-, β-, or γ-CDs (aqueous solutions) as stabilizing agents, employing the chemical reduction method with citric acid as a reducing agent. A comparative study was done to determine which cyclodextrin (CD) was the best stabilizing agent, and we found out that β-CD was the best due to the number of glucopyranose units in its structure. The formation of the Ag-NPs was demonstrated by analysis of UV-vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). SEM-EDS showed the formation of a cluster with a significant amount of silver, for β-CD-Ag-NPs, spherical agglomerates can be observed. However, for α-, γ-CD, the agglomerates do not have a specific form, but their appearance is porous. TEM analysis shows spherical nanoparticles in shape and size between ~0.5 to 7 nm. The clear lattice fringes in TEM images and the typical selected area electron diffraction (SAED) pattern, showed that the Ag-NPs obtained were highly crystalline with a face cubic center structure (FCC). Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and spectroscopic study of CdS nanoparticles using hydrothermal method

NASA Astrophysics Data System (ADS)

AL-Mamoori, Mohammed H. K.; Mahdi, Dunia K.; Al-Shrefi, Saif M.

2018-05-01

In this work, cadmium sulfide nanoparticles (powder) with diameter 50.8 nm was prepared using hydrothermal method. The structural and optical properties of CdS nanoparticles was studied by X-ray diffraction, FESEM, EDS, FTIR, UV-Diffuse Reflectance spectroscopy and Photoluminance spectrum. X-ray diffraction reveal the formation the purity of prepared phase of CdS particles with hexagonal wurtzite structure with particle size 31.8nm by using sheerer equation. The energy dispersion scattering (EDS) examination explains that the sample is composed of a large amount of Cd and S which are exactly CdS nanoparticles and there is a very small trace of (Zn) and (O) element observed because of there is a small pollutions in the measurement place of samples. FESEM shows the spherical shape of nanoparticles with around 50.8 nm diameter. The optical absorption spectral study identified the red shift of the sample in comparison to bulk ZnO in three dimensions. Photoluminance spectrum (PL) at room temperature showed that there are two luminescence peaks at 433.14 nm and 518.21nm. Samples demonstrate a sharp emission band at around 433.18 nm, which is attributed to the typical exciton luminescence. The broad band at 518.21nm which were attributed to the trapped luminescence. The green emission band at 518.21 nm was associated with the emission due to electronic transition from the conduction band to an accepter level due to interstitial sulphur ion.

Evolution processes of the corrosion behavior and structural characteristics of plasma electrolytic oxidation coatings on AZ31 magnesium alloy

NASA Astrophysics Data System (ADS)

Chen, Dong; Wang, Ruiqiang; Huang, Zhiquan; Wu, Yekang; Zhang, Yi; Wu, Guorui; Li, Dalong; Guo, Changhong; Jiang, Guirong; Yu, Shengxue; Shen, Dejiu; Nash, Philip

2018-03-01

Evolution processes of the corrosion behavior and structural characteristics of the plasma electrolytic oxidation (PEO) coated AZ31 magnesium alloy were investigated by using scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), potentio-dynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Detached coating samples were fabricated by an electrochemical method and more details of the internal micro-structure of coatings were clearly observed on the fractured cross-section morphologies of the samples compared to general polished cross-section morphologies. Evolution mechanisms of the coating corrosion behavior in relation to the evolution of micro-structural characteristics were discussed in detail.

Spectral characterization and white light generation by yttrium silicate nanopowders undoped and doped with Ytterbium(III) at different concentrations when excited by a laser diode at 975 nm

NASA Astrophysics Data System (ADS)

Cinkaya, Hatun; Eryurek, Gonul; Bilir, Gokhan; Collins, John; Di Bartolo, Baldassare

2017-01-01

We have studied nanophosphors of yttrium silicate (YSO) undoped and doped with different concentration of ytterbium (Yb3+) synthesized by using the sol-gel method. Structural and luminescence properties of the nanophosphors were studied experimentally by using different analytical techniques. For the structural analysis, we performed X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectrometry (EDS) measurements. Upconversion (UC) and the white light (WL) emission properties were investigated by using the near infrared cw laser excitation of 975 nm. The spectral properties have been found to depend on several physical parameters.

Green synthesis of gold nanoparticles using aspartame and their catalytic activity for p-nitrophenol reduction

NASA Astrophysics Data System (ADS)

Wu, Shufen; Yan, Songjing; Qi, Wei; Huang, Renliang; Cui, Jing; Su, Rongxin; He, Zhimin

2015-05-01

We demonstrated a facile and environmental-friendly approach to form gold nanoparticles through the reduction of HAuCl4 by aspartame. The single-crystalline structure was illustrated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) results indicated that aspartame played a pivotal role in the reduction and stabilization of the gold crystals. The crystals were stabilized through the successive hydrogen-bonding network constructed between the water and aspartame molecules. Additionally, gold nanoparticles synthesized through aspartame were shown to have good catalytic activity for the reduction of p-nitrophenol to p-aminophenol in the presence of NaBH4.

Growth of GaN@InGaN Core-Shell and Au-GaN Hybrid Nanostructures for Energy Applications

DOE PAGES

Kuykendall, Tevye; Aloni, Shaul; Jen-La Plante, Ilan; ...

2009-01-01

We demonstrated a method to control the bandgap energy of GaN nanowires by forming GaN@InGaN core-shell hybrid structures using metal organic chemical vapor deposition (MOCVD). Furthermore, we show the growth of Au nanoparticles on the surface of GaN nanowires in solution at room temperature. The work shown here is a first step toward engineering properties that are crucial for the rational design and synthesis of a new class of photocatalytic materials. The hybrid structures were characterized by various techniques, including photoluminescence (PL), energy dispersive x-ray spectroscopy (EDS), transmission and scanning electron microscopy (TEM and SEM), and x-ray diffraction (XRD).

ZnO:Gd nanocrystals for fluorescent applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Divya, N. K., E-mail: divyank90@gmail.com; Pradyumnan, P. P.

2016-05-23

Gadolinium doped ZnO crystals within the solubility limit of gadolinium in ZnO matrix were prepared by solid state reaction technique. The method is relatively less expense and enables the production in large scale. The samples were characterised by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), UV/Vis diffuse reflectance spectroscopy and photoluminescence techniques. Fluorescent property studies of gadolinium doped ZnO at room temperature show enhanced visible light emission due to the defects and oxygen vacancies produced via doping. This work reports the impact of gadolinium doping in the structural, optical and luminescent properties of ZnO inmore » detail.« less

Plasma in-liquid method for reduction of zinc oxide in zinc nanoparticle synthesis

NASA Astrophysics Data System (ADS)

Amaliyah, Novriany; Mukasa, Shinobu; Nomura, Shinfuku; Toyota, Hiromichi; Kitamae, Tomohide

2015-02-01

Metal air-batteries with high-energy density are expected to be increasingly applied in electric vehicles. This will require a method of recycling air batteries, and reduction of metal oxide by generating plasma in liquid has been proposed as a possible method. Microwave-induced plasma is generated in ethanol as a reducing agent in which zinc oxide is dispersed. Analysis by energy-dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD) reveals the reduction of zinc oxide. According to images by transmission electron microscopy (TEM), cubic and hexagonal metallic zinc particles are formed in sizes of 30 to 200 nm. Additionally, spherical fiber flocculates approximately 180 nm in diameter are present.

Characterization of the Surface Film Formed on Molten AZ91D Magnesium Alloy in Atmospheres Containing SO2

NASA Astrophysics Data System (ADS)

Wang, Xian-Fei; Xiong, Shou-Mei

2012-11-01

The surface film formed on molten AZ91D magnesium alloy in an atmosphere containing SO2 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). The surface film primarily contained MgO and MgS and had a network structure. MgS increased the Pilling-Bedworth ratio of the film and enhanced its protective capability. The films with a few pores at the surface consisted of two layers with an outer MgO layer and an inner layer of MgO and MgS. The film without pores at the surface also contained MgS and small amounts of MgSO4 in the outer layer. Increasing the SO2 content in the atmosphere promoted film growth and the formation of the protective film was prevented with the increased temperature.

Non-Noble Metal Oxide Catalysts for Methane Catalytic Combustion: Sonochemical Synthesis and Characterisation

PubMed Central

Jędrzejczyk, Roman J.; Dziedzicka, Anna; Kuterasiński, Łukasz; Sitarz, Maciej

2017-01-01

The aim of this study was to obtain nanocrystalline mixed metal-oxide–ZrO2 catalysts via a sonochemically-induced preparation method. The effect of a stabiliser’s addition on the catalyst parameters was investigated by several characterisation methods including X-ray Diffraction (XRD), nitrogen adsorption, X-ray fluorescence (XRF), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and µRaman. The sonochemical preparation method allowed us to manufacture the catalysts with uniformly dispersed metal-oxide nanoparticles at the support surface. The catalytic activity was tested in a methane combustion reaction. The activity of the catalysts prepared by the sonochemical method was higher than that of the reference catalysts prepared by the incipient wetness method without ultrasonic irradiation. The cobalt and chromium mixed zirconia catalysts revealed their high activities, which are comparable with those presented in the literature. PMID:28686190

Electrodeposition of gold nanoparticles on mesoporous TiO{sub 2} photoelectrode to enhance visible region photocurrent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supriyono,; Krisnandi, Yuni Krisyuningsih; Gunlazuardi, Jarnuzi, E-mail: jarnuzi@ui.ac.id

2016-04-19

Electrodeposition of gold nanoparticles (Au NPs) on the mesoporous TiO{sub 2} photoelectrode to enchance visible region photocurrent have been investigated. Mesoporous TiO{sub 2} was prepared by a sol gel method and immobilized to the fluorine doped tin oxide (FTO) substrate by dip coating technique. Gold nanoparticles were electrodeposited on the TiO{sub 2} surface and the result FTO/TiO{sub 2}/Au was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-Vis diffuse reflectance spectroscopy (DRS), and X-ray diffraction (XRD). The generated photocurrent was evaluated with an electrochemical workstation (e-DAQ/e-recorder 401) using 60 W wolfram lamp as visible lightmore » source. The photoelectrochemical evaluation indicated that the presence of gold nanoparticles on TiO{sub 2} photoelectrode shall enhance the photocurrent up to 50%.« less

Synthesis of barium-strontium titanate hollow tubes using Kirkendall effect

NASA Astrophysics Data System (ADS)

Chen, Xuncai; Im, SangHyuk; Kim, Jinsoo; Kim, Woo-Sik

2018-02-01

(BaSr)TiO3 hexagonal hollow tubes was fabricated by a solid-state interfacial reaction including a Kirkendall diffusion. Using a co-precipitation and sol-gel process, a core@shell structure of (BaSr)CO3@TiO2 rods were prepared, and then converted to (BaSr)TiO3 hollow tubes at 750 °C. This was a first achievement of single-phase crystal hollow tube. Here, the inner diameter and wall thickness of hollow tube were about 700 nm and 130 nm, respectively. The fabrication of (BaSr)TiO3 hollow tubes was monitored with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to investigate their formation mechanism. The present synthetic approach would provide a new insight into the design and fabrication of hollow architectures of many perovskite oxides.

Characterization of Al-Mg Alloy Aged at Low Temperatures

DOE PAGES

Yi, Gaosong; Cullen, David A.; Littrell, Kenneth C.; ...

2017-02-06

For this research, long-term aged [343 K (70 °C) for 30 months and natural exposure for over 10 years] Al 5456 H116 samples were characterized using electron backscatter diffraction (EBSD), scanning transmission electron microscopy (STEM), state-of-the-art energy-dispersive X-ray spectroscopy (EDS) systems, and small-angle neutron scattering (SANS). ASTM G-67 mass loss tests of the sensitized Al 5456 alloy samples were conducted. Intragranular Mg-rich precipitates, such as Guinier–Preston (GP) zones, were confirmed in Al 5456 H116 aged at 343 K (70 °C) for 30 months, and the volume of these precipitates is 1.39 pct. β' phase is identified at the grain boundarymore » of a navy ship sample, while high-resolution STEM results reveal no intragranular precipitates. Intergranular corrosion (IGC) of Al 5456 was found to be related to the continuity of intergranular precipitates.« less

Composite Ni-Co-fly ash coatings on 5083 aluminium alloy

NASA Astrophysics Data System (ADS)

Panagopoulos, C. N.; Georgiou, E. P.; Tsopani, A.; Piperi, L.

2011-03-01

Ni-Co-fly ash coatings were deposited on zincate treated 5083 wrought aluminium alloy substrates with the aid of the electrodeposition technique. Structural and chemical characterization of the produced composite coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-Co-fly ash coatings were found to consist of a crystalline Ni-Co solid solution with dispersed fly ash particles. In addition, chemical analysis of the Ni-Co matrix showed that it consisted of 80 wt.% Ni and 20 wt.% Co. The co-deposition of fly ash particles leads to a significant increase of the microhardness of the coating. The corrosion behaviour of the Ni-Co-fly ash/zincate coated aluminium alloy, in a 0.3 M NaCl solution (pH = 3.5), was studied by means of potentiodynamic corrosion experiments.

BiOBr microspheres for photocatalytic degradation of an anionic dye

NASA Astrophysics Data System (ADS)

Mera, Adriana C.; Váldes, Héctor; Jamett, Fabiola J.; Meléndrez, M. F.

2017-03-01

BiOBr microspheres were obtained using a solvothermal synthesis route in the presence of ethylene glycol and KBr at 145 °C, for 18 h. BiOBr microspheres were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption-desorption isotherms analysis, diffuse reflectance spectroscopy (DRS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Additionally, the theoretical and experimental isoelectric points (IEP) of BiOBr nanostructured microspheres were determined, and pH's influence on the degradation of an anionic dye (methyl orange) under simulated solar radiation was analyzed. Results show that 97% of methyl orange is removed at pH 2 after 60 min of photocatalytic reaction. Finally, DRIFTS studies permit the proposal of a surface reaction mechanism of the photocatalytic oxidation of MO using BiOBr microspheres.

Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

NASA Astrophysics Data System (ADS)

Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

2016-04-01

Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

A facile synthesis of zinc oxide/multiwalled carbon nanotube nanocomposite lithium ion battery anodes by sol-gel method

NASA Astrophysics Data System (ADS)

Köse, Hilal; Karaal, Şeyma; Aydın, Ali Osman; Akbulut, Hatem

2015-11-01

Free standing zinc oxide (ZnO) and multiwalled carbon nanotube (MWCNT) nanocomposite materials are prepared by a sol gel technique giving a new high capacity anode material for lithium ion batteries. Free-standing ZnO/MWCNT nanocomposite anodes with two different chelating agent additives, triethanolamine (TEA) and glycerin (GLY), yield different electrochemical performances. Field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrometer (EDS), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses reveal the produced anode electrodes exhibit a unique structure of ZnO coating on the MWCNT surfaces. Li-ion cell assembly using a ZnO/MWCNT/GLY free-standing anode and Li metal cathode possesses the best discharge capacity, remaining as high as 460 mAh g-1 after 100 cycles. This core-shell structured anode can offer increased energy storage and performance over conventional anodes in Li-ion batteries.

Nanostructured zirconium phosphate as ion exchanger: Synthesis, size dependent property and analytical application in radiochemical separation.

PubMed

Chakraborty, Rajesh; Bhattacharaya, Koustava; Chattopadhyay, Pabitra

2014-02-01

Nanostructured zirconium phosphates (ZPs) of different sizes were synthesized using Tritron X-100 (polyethylene glycol-p-isooctylphenyl ether) surfactant. The materials were characterized by FTIR and powdered X-ray diffraction (XRD). The structural and morphological details of the material were established by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM study was followed by energy dispersive spectroscopic analysis (EDS) for elemental analysis of the sample. The particle sizes were determined by dynamic light scattering (DLS) method. Ion exchange capacity of these nanomaterials towards different metal ions was measured and size-dependent ion exchange property of the materials was investigated thoroughly. The nanomaterial of the smallest size (ca. 21.04nm) was employed to separate carrier-free (137m)Ba from (137)Cs in column chromatographic technique using 1.0M HNO3 as eluting agent at pH=5. © 2013 Elsevier Ltd. All rights reserved.

Adsorption and mineralization of REE-lanthanum onto bacterial cell surface.

PubMed

Cheng, Yangjian; Zhang, Li; Bian, Xiaojing; Zuo, Hongyang; Dong, Hailiang

2017-07-11

A large number of rare earth element mining and application resulted in a series of problems of soil and water pollution. Environmental remediation of these REE-contaminated sites has become a top priority. This paper explores the use of Bacillus licheniformis to adsorb lanthanum and subsequent mineralization process in contaminated water. The maximum adsorption capacity of lanthanum on bacteria was 113.98 mg/g (dry weight) biomass. X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated that adsorbed lanthanum on bacterial cell surface occurred in an amorphous form at the initial stage. Scanning electron microscopy with X-ray energy-dispersive spectroscopy (SEM/EDS) results indicated that lanthanum adsorption was correlated with phosphate. The amorphous material was converted into scorpion-like monazite (LaPO 4 nanoparticles) in a month. The above results provide a method of using bacterial surface as adsorption and nucleation sites to treat REE-contaminated water.

Synthesis, magnetic and ethanol gas sensing properties of semiconducting magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Al-Ghamdi, Ahmed A.; Al-Hazmi, Faten; Al-Tuwirqi, R. M.; Alnowaiser, F.; Al-Hartomy, Omar A.; El-Tantawy, Farid; Yakuphanoglu, F.

2013-05-01

The superparamagnetic magnetite (Fe3O4) nanoparticles with an average size of 7 nm were synthesized using a rapid and facile microwave hydrothermal technique. The structure of the magnetite nanoparticles was characterized by X-ray diffraction (X-ray), field effect scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe3O4 was shown to have a cubic phase of pure magnetite. Magnetization hysteresis loop shows that the synthesized magnetite exhibits no hysteretic features with a superparamagnetic behavior. The ethanol gas sensing properties of the synthesized magnetite were investigated, and it was found that the responsibility time is less than 10 s with good reproducibility for ethanol sensor. Accordingly, it is evaluated that the magnetite nanoparticles can be effectively used as a solid state ethanol sensor in industrial commercial product applications.

Large-scale preparation of strawberry-like, AgNP-doped SiO2 microspheres using the electrospraying method

NASA Astrophysics Data System (ADS)

Ma, Zhijun; Ji, Huijiao; Tan, Dezhi; Dong, Guoping; Teng, Yu; Zhou, Jiajia; Guan, Miaojia; Qiu, Jianrong; Zhang, Ming

2011-07-01

In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO2 microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

Photoluminescence and charge-transport characteristics of nano-columnar titanium dioxide films prepared by rf-sputtering on alumina templates

NASA Astrophysics Data System (ADS)

Kheirandish, E.; Hosseini, T.; Yavarishad, N.; King, S.; Kouklin, N.

2018-02-01

The current study presents the synthesis and characterization of poly-crystalline TiO2 thin-film prepared by rf-sputtering on top of a highly regimented nanoporous Au-coated Al2O3 substrate. The film’s physical and electronic properties were characterized via SEM, EDS, x-ray diffraction and RAMAN spectroscopy as well as temperature dependent photoluminescence (PL) and I-V measurements. The films feature a 1D, columnar-like structure and exhibit a medium strength, spectrally-broad light emission in the UV-visible range. PL emission shows a weak T-dependence and is attributed to interband electronic transitions and defect-assisted radiative recombinations. The charge transport is confirmed to be polaronic in nature with both thermally-assisted hopping and quantum mechanical tunneling regulating a charge flow within the columns in the intermediate temperature regime of ˜200-320 K. These results open a door to utilizing nano-textured substrates/scaffolds to produce electronic-grade anatase TiO2 by sputtering for advanced opto-electronic device applications.

The nucleation and growth mechanism of Ni-Sn eutectic in a single crystal superalloy

NASA Astrophysics Data System (ADS)

Jiang, Weiguo; Wang, Li; Li, Xiangwei; Lou, Langhong

2017-12-01

The microstructure of single crystal superalloy with and without tin layer on the surface of as-cast and heat-treatment state was investigated by optical microscope (OM) and scanning electron microscopy (SEM). The composition of different regions on the surface was tested by energy dispersive X-ray (EDS). The reaction intermetallic compound (IMC) formed in the heat treatment process was confirmed by X-ray diffraction (XRD). The orientations of different microstructure in samples as heat treatment state were determined by electron back-scattering diffraction (EBSD) method. The porosity location in the interdendritic region was observed by X-ray computed tomography (XCT). The experiment results showed that the remained Sn on the surface of the superalloy reacted with Ni, and then formed Ni3Sn4 in the as-cast state. Sn enriched by diffusion along the porosity located in the interdendritic region and γ + γ‧ (contain a little of Sn) eutectic and Ni3Sn2 formed in single crystal superalloy during heat treatment, and the recalescence behaviors were found. Ni3Sn2 nucleated independently in the cooled liquid at the front of (γ + γ‧) (Sn) eutectic. The nucleation and growth mechanism of the eutectic and Ni3Sn2 IMC during heat treatment was discussed in the present paper.

A novel green synthesis of Fe3O4-Ag core shell recyclable nanoparticles using Vitis vinifera stem extract and its enhanced antibacterial performance

NASA Astrophysics Data System (ADS)

Venkateswarlu, Sada; Natesh Kumar, B.; Prathima, B.; Anitha, K.; Jyothi, N. V. V.

2015-01-01

We described a novel and eco-friendly method for preparing Fe3O4-Ag core shell nanoparticles (CSNPs) with high magnetism and potent antibacterial activity. The Fe3O4-Ag CSNPs were obtained using waste material of Vitis vinifera (grape) stem extract as the green solvent, reducing and capping agent. The result recorded from X-ray powder diffraction (XRD), UV-vis spectrum, energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) supports the biosynthesis and characterization of Fe3O4-Ag CSNPs. From transmission electron microscopy (TEM) the size of the Fe3O4-Ag nanoparticles was measured below 50 nm; high-resolution TEM (HRTEM) indicates the core shell structure; and selected area electron diffraction (SAED) has revealed polycrystalline nature. Vibrating sample magnetometer (VSM) shows the ferromagnetic nature of Fe3O4-Ag CSNPs at room temperature with saturation magnetization of 15.74 emu/g. Further, these biogenic nanoparticles were highly hazardous to microorganisms. The antibacterial activity of biogenic Fe3O4-Ag CSNPs showed potent inhibitory activity against both Gram-positive and Gram-negative pathogens. These nanoparticles may also be reusable because of its excellent ferromagnetic property.

Tribological and corrosion behaviour of electroless Ni-B coating possessing a blackberry like structure

NASA Astrophysics Data System (ADS)

Bülbül, Ferhat; Altun, Hikmet; Küçük, Özkan; Ezirmik, Vefa

2012-08-01

This study aims to evaluate the tribological and corrosion properties of the electroless Ni-B coating deposited on AISI 304 stainless steels. The microstructure of the coating was characterized using x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). XRD analysis revealed that the prepared coating possessed an amorphous character. SEM-EDS investigation also indicated that a non-stoichiometric Ni-B coating was deposited with a columnar growth mechanism on the stainless steel substrate and the morphology of the growth surface was blackberry-like. The hardness and tribological properties were characterized by microhardness and a pin-on-disc wear test. The electroless Ni-B coated sample had a higher degree of hardness, a lower friction coefficient and a lower wear rate than the uncoated substrate. The electrochemical potentiodynamic polarization method was used to evaluate the corrosion resistance of the coating. The electroless Ni-B coating offered cathodic protection on the substrate by acting as a sacrificial anode although it was electrochemically more reactive than the stainless steel substrate.

Mobility of rare earth elements in mine drainage: Influence of iron oxides, carbonates, and phosphates.

PubMed

Edahbi, Mohamed; Plante, Benoît; Benzaazoua, Mostafa; Ward, Matthew; Pelletier, Mia

2018-05-01

The geochemical behavior of rare earth elements (REE) was investigated using weathering cells. The influence of sorption and precipitation on dissolved REE mobility and fractionation is evaluated using synthetic iron-oxides, carbonates, and phosphates. Sorption cell tests are conducted on the main lithologies of the expected waste rocks from the Montviel deposit. The sorbed materials are characterized using a scanning electron microscope (SEM) equipped with a microanalysis system (energy dispersive spectroscopy EDS) (SEM-EDS), X-ray diffraction (XRD), and X-ray absorption near edge structure (XANES) in order to understand the effect of the synthetic minerals on REE mobility. The results confirm that sorption and precipitation control the mobility and fractionation of REE. The main sorbent phases are the carbonates, phosphates (present as accessory minerals in the Montviel waste rocks), and iron oxides (main secondary minerals generated upon weathering of the Montviel lithologies). The XANES results show that REE are present as trivalent species after weathering. Thermodynamic equilibrium calculations results using Visual Minteq suggest that REE could precipitate as secondary phosphates (REEPO 4 ). Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrodeposition of Nanocrystalline Ni–Fe Alloy Coatings Based on 1-Butyl-3-Methylimidazolium-Hydrogen Sulfate Ionic Liquid.

PubMed

He, Xinkuai; Zhang, Chuang; Zhu, Qingyun; Lu, Haozi; Cai, Youxing; Wu, Luye

2017-02-01

The electrodeposition of nanocrystalline Ni–Fe alloy coatings and associated nucleation/growth processes are investigated on the glassy carbon (GC) electrode in 1-butyl-3-methylimidazolium-hydrogen sulfate ([BMIM]HSO4) ionic liquid (IL). Cyclic voltammetric data suggest that the co-electrodeposition of Ni–Fe alloys is quasi-reversible. Moreover, chronoamperometry results indicate that the electrodeposition proceeds via a simultaneous nucleation and three-dimensional growth mechanism. In addition, the effects of electrodeposition potential and electrolyte temperature on the coating thickness and Fe content are also studied. The microstructure and composition of the Ni–Fe alloy coatings on Cu substrate are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS). SEM observations show that these electrodeposits present a dense and compact structure, EDS analysis indicates that the coatings are composed of Ni and Fe, XRD pattern shows the coatings are crystalline with a face-centred cubic (fcc) structure. Tafel plots reveal that the Ni–Fe alloy prepared from [BMIM]HSO4 IL presents better corrosion resistance than that of pure Ni.

Decolorization of Methylene Blue by Persulfate Activated with FeO Magnetic Particles.

PubMed

Hung, Chang-Mao; Chen, Chiu-Wen; Liu, Yi-Yuan; Dong, Cheng-Di

2016-08-01

In this study, the degradation of methylene blue (MB) was conducted to evaluate the feasibility of using persulfate oxidation activated with iron oxide (FeO) magnetic particles. The results demonstrated that the decolorization rate of MB increased with increasing FeO concentration, exhibiting maximum efficiency at pH0 3.0. The kinetics of MB was studied in the binary FeO catalyst and persulfate oxidation system. The surface properties of FeO before and after reaction was analyzed using cyclic voltammogram (CV), three-dimensional excitation-emission fluorescence matrix (EEFM) spectroscopy, zeta potential, particle size distribution measurements, X-ray diffraction (XRD) and environmental scanning electron microscopy-energy dispersive X-ray spectrometry (ESEM-EDS). The CV data indicated that a reversible redox reaction holds the key to explaining the significant activity of the catalyst. EEFM was used to evaluate the catalyst yield of FeO by fluorescence intensity plots with excitation/emission at 220/300 nm and 260/300 nm. The XRD and ESEM-EDS results confirmed the presence of FeO in the catalyst.

Thermoelectric properties of Co₄Sb₁₂ with Bi₂Te₃ nanoinclusions.

PubMed

Ghosh, Sanyukta; Bisht, Anuj; Karati, Anirudha; Rogl, Gerda; Rogl, Peter F; Murty, B S; Suwas, Satyam; Mallik, Ramesh Chandra

2018-01-08

The figure of merit (zT) of a thermoelectric material can be enhanced by incorporation of nanoinclusions into bulk material. The presence of bismuth telluride (Bi2Te3) nanoinclusions in Co4Sb12 leads to lower phonon thermal conductivity by introducing interfaces and defects; it enhances the average zT between 300-700 K. In the current study, Bi2Te3 nanoparticles were dispersed into bulk Co4Sb12 by ball-milling. The bulk was fabricated by spark plasma sintering (SPS). The presence of Bi2Te3 dispersion in Co4Sb12 was confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD) technique. Energy dispersive spectroscopy (EDS) showed antimony (Sb) as an impurity phase for higher contents of Bi2Te3 in the sample. The Seebeck coefficient (S) and electrical conductivity () were measured in the temperature range of 350 - 673 K. The negative value of S indicates that most of the charge carriers were electrons. A decrease in S and increase in with Bi2Te3 content are due to the increased carrier concentration, as confirmed by Hall measurement. The thermal conductivity, measured between 423 - 673 K, decreased due to the increased phonon scattering at interfaces. A maximum zT of 0.17 was achieved at 523 K and it did not vary much throughout the temperature range. The experimental results of composites were compared by using effective medium theories. © 2018 IOP Publishing Ltd.

A single-phase white light emitting Pr3+ doped Ba2CaWO6 phosphor: synthesis, photoluminescence and optical properties

NASA Astrophysics Data System (ADS)

Sreeja, E.; Vidyadharan, Viji; Jose, Saritha K.; George, Anns; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

2018-04-01

Pr3+ doped Ba2CaWO6 phosphor were prepared by traditional high-temperature solid-state reaction technique. The structure evolution was systematically investigated by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The X-ray powder diffraction patterns indicate that the prepared phosphors crystallized in the cubic double-perovskite structure. The functional groups were identified using FTIR spectra and the elements present in the composition were confirmed by the EDS profile. The morphology of the phosphor was identified using SEM and TEM analysis. The PL spectra illustrated that these phosphors could be efficiently excited by charge transfer band of host and the maximum luminescence intensity was observed at 0.06 wt% of Pr3+ ion. Upon the charge transfer band excitation, emission spectra showed peaks at 489, 532, 647, 685 and 737 nm corresponding to 3P0→3H4, 3P1→3H5, 3P0→3F2, 3P0→3F3 and 3P0→3F4 transitions respectively. The concentration quenching of Ba2CaWO6:Pr3+ phosphor can be mainly attributed to dipole-dipole interaction. The CIE coordinates were estimated to be close to the white region. The decay curves are well fitted with double exponential decay models. The standard and modified Judd-Ofelt (JO) theories were used to determine the Judd-Ofelt intensity parameters, radiative transition probabilities and branching ratios. The optical properties indicate that Ba2CaWO6:Pr3+ phosphors can produce white light emission from a single phase host and its potential application for solid-state lighting and display devices.

Arsenic entrapment by nanocrystals of Al-magnetite: The role of Al in crystal growth and As retention.

PubMed

Freitas, Erico T F; Stroppa, Daniel G; Montoro, Luciano A; de Mello, Jaime W V; Gasparon, Massimo; Ciminelli, Virginia S T

2016-09-01

The nature of As-Al-Fe co-precipitates aged for 120 days are investigated in detail by High Resolution Transmission Electron Microscopy (HRTEM), Scanning TEM (STEM), electron diffraction, Energy Dispersive X-Ray Spectroscopy (EDS), Electron Energy-Loss Spectroscopy (EELS), and Energy Filtered Transmission Electron Microscopy (EFTEM). The Al present in magnetite is shown to favour As incorporation (up to 1.10 wt%) relative to Al-free magnetite and Al-goethite, but As uptake by Al-magnetite decreases with increasing Al substitution (3.53-11.37 mol% Al). Arsenic-bearing magnetite and goethite mesocrystals (MCs) are formed by oriented aggregation (OA) of primary nanoparticles (NPs). Well-crystalline magnetite likely formed by Otswald ripening was predominant in the Al-free system. The As content in Al-goethite MCs (having approximately 13% substituted Al) was close to the EDS detection limit (0.1 wt% As), but was below detection in Al-goethites with 23.00-32.19 mol% Al. Our results show for the first time the capacity of Al-magnetite to incorporate more As than Al-free magnetite, and the role of Al in favouring OA-based crystal growth under the experimental conditions, and therefore As retention in the formed MCs. The proposed mechanism of As incorporation involves adsorption of As onto the newly formed NPs. Arsenic is then trapped in the MCs as they grow by self-assembly OA upon attachment of the NPs. We conclude that Al may diffuse to the crystal faces with high surface energy to reduce the total energy of the system during the attachment events, thus favouring the oriented aggregation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ionic liquid-assisted preparation of square-shaped Y{sub 2}O{sub 3} nanoplates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lei; Fang, Hao; Xu, Hualan

Highlights: • Y{sub 4}O(OH){sub 9}(NO{sub 3}) nanosheets were prepared by an ionic liquid-assisted mixed solvothermal route. • Y{sub 2}O{sub 3} nanosheets were obtained after calcining the Y{sub 4}O(OH){sub 9}(NO{sub 3}) nanosheets. • The Y{sub 2}O{sub 3} nanosheets are with length of about 300 nm and thickness of several nanometers. - Abstract: Uniform square-shaped Y{sub 4}O(OH){sub 9}(NO{sub 3}) nanoplates with side length of about 300 nm and thickness of tens of nanometers have been successfully prepared by an ionic liquid-assisted mixed solvothermal route. Y{sub 2}O{sub 3} nanoplates with similar size were obtained after calcining the Y{sub 4}O(OH){sub 9}(NO{sub 3}) nanoplates atmore » 800 °C. The products were analyzed by powder X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), and electron diffraction (ED). The effects of reaction time, composition of solvents, and the molar ratio of reagents on the morphology of the products have been investigated. The possible formation mechanism of the Y{sub 4}O(OH){sub 9}(NO{sub 3}) nanoplates was also discussed. Y{sub 2}O{sub 3}:Eu{sup 3+} nanoplates were also synthesized and their photoluminescent properties were examined.« less

The optimization functions of ICP discharge in preparation of Cu-Zn-Sn precursors and CZTS films by co-evaporation

NASA Astrophysics Data System (ADS)

Ye, Li; Junfang, Chen; Junhui, Ma; Lifen, Zhou

2016-02-01

Cu-Zn-Sn (CZT) precursors were successfully prepared on glass substrate with the introduction of the assistant technology ICP (inductively coupled plasma) based on the conventional co-evaporation process. The deposition was performed with the substrate temperature at 220 °C and the chamber pressure at 6.5 × 10-2 Pa. Argon plasma was investigated with a Langmuir probe. The plasma density and the electron temperature increased with the increasing of the discharge power. The impact of ICP discharge power on the structural and morphological properties of the CZT film were investigated with energy dispersive X-ray spectrometers (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD and EDS were combined to investigate the structure of the film. The results show that Zn loss exists during the evaporation and the loss can be reduced by increasing the ICP discharge power. From the observation on the scanning electron microscope, the grain size becomes larger with argon plasma's assistance. The preparation of the Cu2ZnSnS4 (CZTS) film and the measured properties demonstrate that the ICP would optimize the growth of the film. Project supported by the Natural Science Foundation of Guangdong Province, China (No. S2013010012548), the Natural Science Foundation of Guangdong Province, China (No. 10151063101000048), the Key Program of the National Natural Science Foundation of China (No. 61072028), the Guangdong Provincial Natural Science Foundation of China (No. 2014A030313441), and the Guangdong Province and Chinese Ministry of Education Cooperation Project of Industry, Education and Academy (No. 2013B090600063).

Electrochemical Study of Cobalt in Urea and Choline Chloride

NASA Astrophysics Data System (ADS)

Li, Min; Shi, Zhongning; Wang, Zhaowen; Reddy, Ramana G.

The nucleation mechanism of Co(II) in urea-choline chloride-CoCl2 melt at 373 K was studied using chronoamperometry. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode is governed by three-dimensional (3D) progressive nucleation and diffusion-controlled growth mechanisms. The average diffusion coefficient of Co(II) in the melt at 373 K is 1.1 × 10-6 cm2 s-1, which is in good agreement with the estimated value obtained from cyclic voltammetry data. Characterization of the Co electrodeposit using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques indicate that the electrodeposit obtained at -0.75 V and 373 K contain dense and compact surface formed from pure cobalt metal.

Superhydrophobic coatings on wood substrate for self-cleaning and EMI shielding

NASA Astrophysics Data System (ADS)

Xing, Yingjie; Xue, Yaping; Song, Jinlong; Sun, Yankui; Huang, Liu; Liu, Xin; Sun, Jing

2018-04-01

A layer of superhydrophobic coating having good electromagnetic shielding and self-cleaning performance was fabricated on a wood surface through an electroless copper plated process. The superhydrophobic property of the wood surface was measured by contact angle (CA) and roll-off angle (RA) measurements. The microstructure and chemical composition of the superhydrophobic coating were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The analysis revealed that the microscale particles were uniformly distributed on the wood surface and the main component of the coating is metallic copper. The as-prepared Cu coatings on wood substrate exhibit a good superhydrophobicity with water contact angle about 160° and rolling angle less than 5°.

High-pressure Irreversible Amorphization of La1/3NbO3

DOE Office of Scientific and Technical Information (OSTI.GOV)

I Halevy; A Hen; A Broide

2011-12-31

The crystallographic structure of La{sub 1/3}NbO{sub 3} perovskite was studied at high pressures using a diamond-anvil cell and synchrotron radiation. High-pressure energy dispersive (EDS) x-ray diffraction and high-pressure angle dispersive (ADS) x-ray diffraction revealed an irreversible amorphization at {approx}10 GPa. A large change in the bulk modulus accompanied the high-pressure amorphization.

Pocket Electronic Dictionaries for Second Language Learning: Help or Hindrance?

ERIC Educational Resources Information Center

Tang, Gloria M.

1997-01-01

Reports on the concerns of English-as-a-Second-Language (ESL) teachers in Canada regarding their students' use of pocket bilingual electronic dictionaries (EDs). The article highlights the ED's features, uses, and effectiveness as a tool for learning ESL at the secondary level and ESL students' perceptions of the ED's usefulness. (nine references)…

Improvement of pentathiophene/fullerene planar heterojunction photovoltaic cells by improving the organic films morphology through the anode buffer bilayer

NASA Astrophysics Data System (ADS)

El Jouad, Zouhair; Cattin, Linda; Martinez, Francisco; Neculqueo, Gloria; Louarn, Guy; Addou, Mohammed; Predeep, Padmanabhan; Manuvel, Jayan; Bernède, Jean-Christian

2016-05-01

Organic photovoltaic cells (OPVCs) are based on a heterojunction electron donor (ED)/electron acceptor (EA). In the present work, the electron donor which is also the absorber of light is pentathiophene. The typical cells were ITO/HTL/pentathiophene/fullerene/Alq3/Al with HTL (hole transport layer) = MoO3, CuI, MoO3/CuI. After optimisation of the pentathiophene thickness, 70 nm, the highest efficiency, 0.81%, is obtained with the bilayer MoO3/CuI as HTL. In order to understand these results the pentathiophene films deposited onto the different HTLs were characterized by scanning electron microscopy, atomic force microscopy, X-rays diffraction, optical absorption and electrical characterization. It is shown that CuI improves the conductivity of the pentathiophene layer through the modification of the film structure, while MoO3 decreases the leakage current. Using the bilayer MoO3/CuI allows cumulating the advantages of each layer. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer

NASA Astrophysics Data System (ADS)

Simões, Sónia; Viana, Filomena; Koçak, Mustafa; Ramos, A. Sofia; Vieira, M. Teresa; Vieira, Manuel F.

2012-05-01

In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl.

Discontinuous precipitation in a nickel-free high nitrogen austenitic stainless steel on solution nitriding

NASA Astrophysics Data System (ADS)

Mohammadzadeh, Roghayeh; Akbari, Alireza; Grumsen, Flemming B.; Somers, Marcel A. J.

2017-10-01

Chromium-rich nitride precipitates in production of nickel-free austenitic stainless steel plates via pressurised solution nitriding of Fe-22.7Cr-2.4Mo ferritic stainless steel at 1473 K (1200 °C) under a nitrogen gas atmosphere was investigated. The microstructure, chemical and phase composition, morphology and crystallographic orientation between the resulted austenite and precipitates were investigated using optical microscopy, X-ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (TEM) and Electron Back Scatter Diffraction (EBSD). On prolonged nitriding, Chromium-rich nitride precipitates were formed firstly close to the surface and later throughout the sample with austenitic structure. Chromium-rich nitride precipitates with a rod or strip-like morphology was developed by a discontinuous cellular precipitation mechanism. STEM-EDS analysis demonstrated partitioning of metallic elements between austenite and nitrides, with chromium contents of about 80 wt.% in the precipitates. XRD analysis indicated that the Chromium-rich nitride precipitates are hexagonal (Cr, Mo)2N. Based on the TEM studies, (Cr, Mo)2N precipitates presented a (1 1 1)γ//(0 0 2)(Cr, Mo)2N, ?γ//?(Cr, Mo)2N orientation relationship with respect to the austenite matrix. EBSD studies revealed that the austenite in the regions that have transformed into austenite and (Cr, Mo)2N have no orientation relation to the untransformed austenite.

Preparation and cathodoluminescence characteristics of rare earth activated BaAl2O4 phosphors.

PubMed

Benourdja, S; Kaynar, Ümit H; Ayvacikli, M; Karabulut, Y; Guinea, J Garcia; Canimoglu, A; Chahed, L; Can, N

2018-04-18

Undoped and Pr, Sm and Tb activated BaAl 2 O 4 phosphors have been synthesized by solid state reaction method and combustion method. The structure and morphological observation of the phosphor samples were monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersive X-ray spectrometer (EDS). The all diffraction peaks are well assigned to standard data card (PDF♯17-306). Emission properties of the samples were explored using light emission induced by an electron beam (i.e cathodoluminescence, CL) at room temperature (RT). Undoped BaAl 2 O 4 sample exhibits a broad defect emission from 300 to 500 nm from the aluminate defect centres. CL spectra recorded at room temperature display that the as-prepared BaAl 2 O 4 :Ln (Ln=Pr, Sm and Tb) phosphors exhibit different luminescence colors coming from different rare earth activator ions. The transition 4 G 5/2 → 6 H 7/2 located at 606 and 610 nm for Sm 3+ can occur as hypersensitive transition having the selection rule ΔJ = ± 1. For the Tb 3+ doped samples, they exhibit D45 green line emissions. The proposed luminescent mechanisms of all doped rare earth ions are also discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Kinematical calculations of RHEED intensity oscillations during the growth of thin epitaxial films

NASA Astrophysics Data System (ADS)

Daniluk, Andrzej

2005-08-01

A practical computing algorithm working in real time has been developed for calculating the reflection high-energy electron diffraction (RHEED) from the molecular beam epitaxy (MBE) growing surface. The calculations are based on the use of kinematical diffraction theory. Simple mathematical models are used for the growth simulation in order to investigate the fundamental behaviors of reflectivity change during the growth of thin epitaxial films prepared using MBE. Program summaryTitle of program:GROWTH Catalogue identifier:ADVL Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVL Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Distribution format: tar.gz Computer for which the program is designed and others on which is has been tested:Pentium-based PC Operating systems or monitors under which the program has been tested:Windows 9x, XP, NT Programming language used:Object Pascal Memory required to execute with typical data:more than 1 MB Number of bits in a word: 64 bits Number of processors used: 1 Number of lines in distributed program, including test data, etc.: 10 989 Number of bytes in distributed program, including test data, etc.:103 048 Nature of the physical problem:Reflection high-energy electron diffraction (RHEED) is a very useful technique for studying growth and surface analysis of thin epitaxial structures prepared using the molecular beam epitaxy (MBE). The simplest approach to calculating the RHEED intensity during the growth of thin epitaxial films is the kinematical diffraction theory (often called kinematical approximation), in which only a single scattering event is taken into account. The biggest advantage of this approach is that we can calculate RHEED intensity in real time. Also, the approach facilitates intuitive understanding of the growth mechanism and surface morphology [P.I. Cohen, G.S. Petrich, P.R. Pukite, G.J. Whaley, A.S. Arrott, Surf. Sci. 216 (1989) 222]. Method of solution:Epitaxial growth of thin films is modeled by a set of non-linear differential equations [P.I. Cohen, G.S. Petrich, P.R. Pukite, G.J. Whaley, A.S. Arrott, Surf. Sci. 216 (1989) 222]. The Runge-Kutta method with adaptive stepsize control was used for solving initial value problem for non-linear differential equations [W.H. Press, B.P. Flannery, S.A. Teukolsky, W.T. Vetterling, Numerical Recipes in Pascal: The Art of Scientific Computing; first ed., Cambridge University Press, 1989; See also: Numerical Recipes in C++, second ed., Cambridge University Press, 1992]. Typical running time: The typical running time is machine and user-parameters dependent. Unusual features of the program: The program is distributed in the form of a main project Growth.dpr file and an independent Rhd.pas file and should be compiled using Object Pascal compilers, including Borland Delphi.

Surface mechanical behaviour of composite Ni-P-fly ash/zincate coated aluminium alloy

NASA Astrophysics Data System (ADS)

Panagopoulos, C. N.; Georgiou, E. P.

2009-04-01

Ni-P-fly ash coatings were produced on zincate coated 5083 wrought aluminium alloy substrates with the aid of an electroless deposition technique. Structural and chemical characterization of the produced coatings was performed with the aid of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDS) techniques. The Ni-P-fly ash coating was found to consist of an amorphous Ni-P matrix with dispersed fly ash particles. The wear resistance of the Ni-P-fly ash coating on zincate treated aluminium alloy was observed to be higher than that of the bare aluminium alloy, when sliding against a stainless steel counterface. In addition, the adhesion between the Ni-P-fly ash/zincate coating and the aluminium alloy substrate was also studied with a scratch testing apparatus. The adhesion strength of Ni-P-fly ash/zincate coating on the aluminium alloy substrate was observed to be higher in comparison to the Ni-P/zincate coating on the same aluminium alloy.

Trimethylamine Sensors Based on Au-Modified Hierarchical Porous Single-Crystalline ZnO Nanosheets.

PubMed

Meng, Fanli; Zheng, Hanxiong; Sun, Yufeng; Li, Minqiang; Liu, Jinhuai

2017-06-22

It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA). Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs)-based sensors. The HPSCZNs were synthesized through a one-pot wet-chemical method followed by an annealing treatment. Polyethyleneimine (PEI) was used to modify the surface of the HPSCZNs, and then the PEI-modified samples were mixed with Au nanoparticles (NPs) sol solution. Electrostatic interactions drive Au nanoparticles loading onto the surface of the HPSCZNs. The Au-modified HPSCZNs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS), respectively. The results show that Au-modified HPSCZNs-based sensors exhibit a high response to TMA. The linear range is from 10 to 300 ppb; while the detection limit is 10 ppb, which is the lowest value to our knowledge.

Improving adsorption and activation of the lipase immobilized in amino-functionalized ordered mesoporous SBA-15

NASA Astrophysics Data System (ADS)

Xu, Yun-qiang; Zhou, Guo-wei; Wu, Cui-cui; Li, Tian-duo; Song, Hong-bin

2011-05-01

Ordered mesoporous SBA-15 was prepared by hydrothermal process and was functionalized with(3-aminopropyl) triethoxysilane (APTES) by post-synthesis-grafting method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS), small-angle X-ray powder diffraction (SAXRD), N 2 adsorption-desorption and Fourier transform infrared spectroscopy (FT-IR). The results indicated that SBA-15 had a 2-dimensional hexagonal p6 mm mesoscopic structure and the mesoscopic structure was remained after the functionalization procedure. The activities of porcine pancreatic lipase (PPL) immobilized in SBA-15 by physical adsorption and in APTES functionalized SBA-15 by chemical adsorption were studied by hydrolysis of triacetin. Chemically adsorbed PPL showed higher loading amount and catalytic activity comparing with physically adsorbed PPL. The stability of immobilized PPL against thermal and pH of reaction medium was significantly improved. Recycling experiments showed that chemically adsorbed PPL exhibited better reusability than physically adsorbed PPL.

Large-scale synthesis and microwave absorption enhancement of actinomorphic tubular ZnO/CoFe2O4 nanocomposites.

PubMed

Cao, Jing; Fu, Wuyou; Yang, Haibin; Yu, Qingjiang; Zhang, Yanyan; Liu, Shikai; Sun, Peng; Zhou, Xiaoming; Leng, Yan; Wang, Shuangming; Liu, Bingbing; Zou, Guangtian

2009-04-09

Actinomorphic tubular ZnO/CoFe(2)O(4) nanocomposites were fabricated in large scale via a simple solution method at low temperature. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The as-synthesized nanocomposites were uniformly dispersed into the phenolic resin then the mixture was pasted on metal plate with the area of 200 mm x 200 mm as the microwave absorption test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The range of microwave absorption is from 2 to 18 Hz and the best microwave absorption reach to 28.2 dB at 8.5 Hz. The results indicate that the composites are of excellence with respect to microwave absorption.

Ultrasound-assisted synthesis of CuO nanostructures templated by cotton fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Yunling, E-mail: zouyunling1999@126.com; Li, Yan; Guo, Ying

Highlights: ► Flower-like and corn-like CuO nanostructures were synthesized by a simple method. ► Cotton fibers purchased from commercially are used as template. ► The concentration of Cu(NO{sub 3}){sub 2} solution is an important parameter. -- Abstract: Flower-like and corn-like CuO nanostructures composed of CuO nanoparticles were successfully synthesized via ultrasound-assisted template method, respectively, by controlling the initial concentration of Cu(NO{sub 3}){sub 2} solution. Here, cotton fibers were used as template agent. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM) and energy-dispersive spectroscopy (EDS), respectively. The results demonstrated that the initialmore » concentration of Cu(NO{sub 3}){sub 2} solution was an important parameter for determining whether CuO nanoparticles assembled into flower-like structures or corn-like structures. The mechanism of forming different nanostructures of CuO was discussed.« less

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Enhanced photoelectrochemical performance of Ti-doped hematite thin films prepared by the sol-gel method

NASA Astrophysics Data System (ADS)

Lian, Xiaojuan; Yang, Xin; Liu, Shangjun; Xu, Ying; Jiang, Chunping; Chen, Jinwei; Wang, Ruilin

2012-01-01

Ti-doped α-Fe2O3 thin films were successfully prepared on FTO substrates by the sol-gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed α-Fe2O3 had a preferred (1 1 0) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed at high temperature. The IPCE could reach 32.6% at 400 nm without any additional potential vs. SCE. Titanium in the lattice can affect the photo electro chemical performance positively by increasing the conductivity of the thin film. So the excited electrons and holes could live longer, rather than recombining with each other rapidly as undoped hematite. And the efficient carrier density on the Ti-doped anode surface was higher than the undoped anode, which contribute to the well PEC performance.

Green synthesis of the Pd nanoparticles supported on reduced graphene oxide using barberry fruit extract and its application as a recyclable and heterogeneous catalyst for the reduction of nitroarenes.

PubMed

Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Alizadeh, Mohammad; Bagherzadeh, Mojtaba

2016-03-15

Through this manuscript the green synthesis of palladium nanoparticles supported on reduced graphene oxide (Pd NPs/RGO) under the mild conditions through reduction of the graphene oxide and Pd(2+) ions using barberry fruit extract as reducing and stabilizing agent is reported. The as-prepared Pd NPs/RGO was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The Pd NPs/RGO could be used as an efficient and heterogeneous catalyst for reduction of nitroarenes using sodium borohydride in an environmental friendly medium. Excellent yields of products were obtained with a wide range of substrates and the catalyst was recycled multiple times without any significant loss of its catalytic activity. Copyright © 2015 Elsevier Inc. All rights reserved.

High-strength bioresorbable Fe-Ag nanocomposite scaffolds: Processing and properties

NASA Astrophysics Data System (ADS)

Sharipova, Aliya; Psakhie, Sergey G.; Swain, Sanjaya K.; Gutmanas, Elazar Y.; Gotman, Irena

2015-10-01

High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na2SO4 and K2CO3 salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy's law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18-22 MPa), compressive strength of 8-12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6-6 cm2) is close to the range of trabecular bone.

Achillea millefolium L. extract mediated green synthesis of waste peach kernel shell supported silver nanoparticles: Application of the nanoparticles for catalytic reduction of a variety of dyes in water.

PubMed

Khodadadi, Bahar; Bordbar, Maryam; Nasrollahzadeh, Mahmoud

2017-05-01

In this paper, silver nanoparticles (Ag NPs) are synthesized using Achillea millefolium L. extract as reducing and stabilizing agents and peach kernel shell as an environmentally benign support. FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDS), Thermo gravimetric-differential thermal analysis (TG-DTA) and Transmission Electron Microscopy (TEM) were used to characterize peach kernel shell, Ag NPs, and Ag NPs/peach kernel shell. The catalytic activity of the Ag NPs/peach kernel shell was investigated for the reduction of 4-nitrophenol (4-NP), Methyl Orange (MO), and Methylene Blue (MB) at room temperature. Ag NPs/peach kernel shell was found to be a highly active catalyst. In addition, Ag NPs/peach kernel shell can be recovered and reused several times with no significant loss of its catalytic activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Wet etching mechanism and crystallization of indium-tin oxide layer for application in light-emitting diodes

NASA Astrophysics Data System (ADS)

Su, Shui-Hsiang; Kong, Hsieng-Jen; Tseng, Chun-Lung; Chen, Guan-Yu

2018-01-01

In the article, we describe the etching mechanism of indium-tin oxide (ITO) film, which was wet-etched using a solution of hydrochloric acid (HCl) and ferric chloride (FeCl3). The etching mechanism is analyzed at various etching durations of ITO films by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and selective area diffraction (SAD) analysis. In comparison with the crystalline phase of SnO2, the In2O3 phase can be more easily transformed to In3+ and can form an inverted conical structure during the etching process. By adjusting the etching duration, the residual ITO is completely removed to show a designed pattern. This is attributed to the negative Gibbs energy of In2O3 transformed to In3+. The result also corresponds to the finding of energy-dispersive X-ray spectroscopy (EDS) analysis that the Sn/In ratio increases with increasing etching duration.

Mechanochemical solvent-free in situ synthesis of drug-loaded {Cu2(1,4-bdc)2(dabco)}n MOFs for controlled drug delivery

NASA Astrophysics Data System (ADS)

Nadizadeh, Zahra; Naimi-Jamal, M. Reza; Panahi, Leila

2018-03-01

In the present study, ibuprofen-loaded nano metal-organic frameworks (NMOFs) {Cu2(1,4-bdc)2(dabco)}n and {Cu2(1,4-bdc-NH2)2(dabco)}n (bdc=benzenedicarboxylic acid, and dabco=diazabicyclooctane) were synthesized by ball-milling at room temperature in 2 h. The produced drug-loaded Cu-NMOFs were studied as ibuprofen drug delivery system and exhibited well-defined drug release behavior, exceptionally high drug loading capacities and the ability to entrap the model drug. The loading efficiency for ibuprofen was determined about 50.54% and 50.27%, respectively. The drug release of NMOFs was also monitored, and all of the loaded drug was released in 1 day. The NMOFs were characterized by FT-IR spectroscopy, X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), SEM (scanning electron microscopy), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma (ICP), UV-vis spectroscopy and N2 adsorption porosimetry (BET&BJH).

Evaluation of cell toxicity and DNA and protein binding of green synthesized silver nanoparticles.

PubMed

Ribeiro, A P C; Anbu, S; Alegria, E C B A; Fernandes, A R; Baptista, P V; Mendes, R; Matias, A S; Mendes, M; Guedes da Silva, M F C; Pombeiro, A J L

2018-05-01

Silver nanoparticles (AgNPs) were prepared by GREEN chemistry relying on the reduction of AgNO 3 by phytochemicals present in black tea extract. AgNPs were fully characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy ((UV-vis)), X-ray diffraction (XRD) and energy dispersive absorption spectroscopy (EDS). The synthesized AgNPs induced a decrease of the cell viability in a dose-dependent manner with a low IC 50 (0.5 ± 0.1 μM) for an ovarian carcinoma cell line (A2780) compared to primary human fibroblasts (IC 50 5.0 ± 0.1 μM). The DNA binding capability of CT (calf thymus) DNA was investigated using electronic absorption and fluorescence spectroscopies, circular dichroism and viscosity titration methods. Additionally, the AgNPs strongly quench the intrinsic fluorescence of BSA, as determined by synchronous fluorescence spectra. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Trimethylamine Sensors Based on Au-Modified Hierarchical Porous Single-Crystalline ZnO Nanosheets

PubMed Central

Zheng, Hanxiong; Sun, Yufeng; Li, Minqiang; Liu, Jinhuai

2017-01-01

It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA). Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs)-based sensors. The HPSCZNs were synthesized through a one-pot wet-chemical method followed by an annealing treatment. Polyethyleneimine (PEI) was used to modify the surface of the HPSCZNs, and then the PEI-modified samples were mixed with Au nanoparticles (NPs) sol solution. Electrostatic interactions drive Au nanoparticles loading onto the surface of the HPSCZNs. The Au-modified HPSCZNs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS), respectively. The results show that Au-modified HPSCZNs-based sensors exhibit a high response to TMA. The linear range is from 10 to 300 ppb; while the detection limit is 10 ppb, which is the lowest value to our knowledge. PMID:28640226

Nb2O5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(VI).

PubMed

Du, Yucheng; Zhang, Shihao; Wang, Jinshu; Wu, Junshu; Dai, Hongxing

2018-04-01

Niobium oxide nanowire-deposited carbon fiber (CF) samples were prepared using a hydrothermal method with amorphous Nb 2 O 5 ·nH 2 O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV-visible spectroscopy (UV-vis), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr(VI) was determined. Parameters such as pH value and initial Cr(VI) concentration could influence the Cr(VI) removal efficiency or adsorption capacity of the Nb 2 O 5 /carbon fiber sample obtained after hydrothermal treatment at 160°C for 14hr. The maximal Cr(VI) adsorption capacity of the Nb 2 O 5 nanowire/CF sample was 115mg/g. This Nb 2 O 5 /CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr(VI) under UV-light irradiation: the Cr(VI) removal efficiency reached 99.9% after UV-light irradiation for 1hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr(VI) adsorption capacity and photocatalytic performance was related to its high surface area, abundant surface hydroxyl groups, and good UV-light absorption ability. Copyright © 2017. Published by Elsevier B.V.

Characterization of Limestone as Raw Material to Hydrated Lime

NASA Astrophysics Data System (ADS)

Salem Hwidi, Rajeb; Nuraiti Tengku Izhar, Tengku; Saad, Farah Naemah Mohd

2018-03-01

In Malaysia, limestone is essentially important for the economic growth as raw materials in the industry sector. Nevertheless, a little attention was paid to the physical, chemical, mineralogical, and morphological properties of the limestone using X-ray fluorescence (X-RF), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM-EDS) respectively. Raw materials (limestone rocks) were collected from Bukit Keteri area, Chuping, Kangar, Perlis, Malaysia. Lab crusher and lab sieved were utilized to prepare five different size of ground limestone at (75 µm, 150 µm, 225 µm, 300, and 425 µm) respectively. It is found that the main chemical composition of bulk limestone was Calcium oxide (CaO) at 97.58 wt.% and trace amount of MnO, Al2O3, and Fe2O3 at 0.02%, 0.35%, and 0.396% respectively. XRD diffractograms showed characteristic peaks of calcite and quartz. Furthermore, main FTIR absorption bands at 1,419, 874.08 and 712.20 cm-1 indicated the presence of calcite. The micrographs showed clearly the difference of samples particle size. Furthermore, EDS peaks of Ca, O, and C elements confirmed the presence of CaCO3 in the samples.

Biosensing applications of titanium dioxide coated graphene modified disposable electrodes.

PubMed

Kuralay, Filiz; Tunç, Selma; Bozduman, Ferhat; Oksuz, Lutfi; Oksuz, Aysegul Uygun

2016-11-01

In the present work, preparation of titanium dioxide coated graphene (TiO2/graphene) and the use of this nanocomposite modified electrode for electrochemical biosensing applications were detailed. The nanocomposite was prepared with radio frequency (rf) rotating plasma method which serves homogeneous distribution of TiO2 onto graphene. TiO2/graphene was characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Then, this nanocomposite was dissolved in phosphate buffer solution (pH 7.4) and modified onto disposable pencil graphite electrode (PGE) by dip coating for the investigation of the biosensing properties of the prepared electrode. TiO2/graphene modified PGE was characterized with SEM, EDS and cyclic voltammetry (CV). The sensor properties of the obtained surface were examined for DNA and DNA-drug interaction. The detection limit was calculated as 1.25mgL(-1) (n=3) for double-stranded DNA (dsDNA). RSD% was calculated as 2.4% for three successive determinations at 5mgL(-1) dsDNA concentration. Enhanced results were obtained compared to the ones obtained with graphene and unmodified (bare) electrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis, structural and magnetic properties of Mg0.6Zn0.4CrxFe2-xO4 (0.0 ≤ x ≤ 2.0) nano ferrite

NASA Astrophysics Data System (ADS)

Verma, R.; Kane, S. N.; Raghuvanshi, S.; Satalkar, M.; Modak, S. S.; Mazaleyrat, F.

2018-05-01

Present study reports, effect on structural, magnetic properties of Cr doped Mg-Zn nano-ferrite: Mg0.6Zn0.4CrxFe2-xO4 (0.0≤ x≤2.0), synthesized by sol-gel auto combustion method. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were utilized to monitor the effect of Cr substitution on structural, magnetic properties, and correlation between them. XRD confirms the formation of single phase spinel nano ferrite with particle size ranging between 3.9 - 40.5 nm, whereas EDS confirms the formation of the estimated ferrite composition. Distribution of Mg, Zn, Cr, Fe cations on tetrahedral (A), octahedral (B) site show mixed spinel structure. Increase of Cr content leads to increase of specific surface area (4.35 - 28.28 m2/g), decrease of experimental saturation magnetization at 300 K (varies between 0.57 - 40.95 Am2/kg), and theoretical magnetization at 0 K (range between 13.37 - 56.77 Am2/kg). Observed changes in coercivity values reflect soft magnetic nature of the studied ferrites.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

NASA Astrophysics Data System (ADS)

Deshpande, Aniruddha S.; Khomane, Ramdas B.; Vaidya, Bhalchandra K.; Joshi, Renuka M.; Harle, Arti S.; Kulkarni, Bhaskar D.

2008-06-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+ malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 and n-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5 15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Characterisation of Sol-Gel Synthesis of Phase Pure CaTiO3 Nano Powders after Drying

NASA Astrophysics Data System (ADS)

Mallik, P. K.; Biswal, G.; Patnaik, S. C.; Senapati, S. K.

2015-02-01

According to a few recent studies, calcium titanate (CT) is a material that is similar to hydroxyapatite in biological properties. However, calcium titanate is not currently being used in the biomedical applications as to hydroxyapatite. The objective is to prepare nano calcium titanate powders from the equimolar solution of calcium oxide, ethanol and Titanium (IV) isopropoxide via sol-gel synthesis. The phase analysis and morphology of powder particles were studied by X-ray diffraction (XRD), while the composition and size of powder particles were determined by Transmission electron microscope (TEM) attached with energy dispersive x-ray spectrometer (EDS). As results, XRD confirm the presence of phase pure crystalline CaTiO3 after drying at 100°C for 24 hours, while TEM analysis confirms about 13 nm sizes of CaTiO3 particles and some agglomerated particle of 20-30 nm. Moreover, EDS analysis indicates that the approximately stoichiometric Ca/Ti ratio 1:1 was obtained in the CaTiO3 powders. Finally, it can be concluded that described sol-gel synthesis could be novel method for the production of nano CaTiO3 particles at lower temperature compared to any other methods of production.

Polyamidoamine dendrimers-assisted electrodeposition of gold-platinum bimetallic nanoflowers.

PubMed

Qian, Lei; Yang, Xiurong

2006-08-24

Novel Au-Pt bimetallic flower nanostructures fabricated on a polyamidoamine dendrimers-modified surface by electrodeposition are reported. These polyamidoamine dendrimers were stable, and they assisted the formation of Au-Pt bimetallic nanoflowers during the electrodeposition process. These nanoflowers were characterized by field-emitted scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and electrochemical methods. FE-SEM images showed that the bimetallic nanoflower included two parts: the "light" and the "pale" part. The two parts consisted of many small bimetallic nanoparticles, which was attributed to the progressive nucleation process. Moreover, the "light" part contained more bimetallic nanoparticles. The morphologies of bimetallic nanoflowers depended on the electrodeposition time and potential and the layer number of assembled dendrimers. The average size of nanoflowers increased with the increase in electrodeposition time. The layer number of assembled dendrimers obviously affected the size and morphologies of the "pale" parts of deposited nanoflowers. EDS and XPS indicated that the content of Au element was higher than that of Pt element in the nanoflowers. The bimetallic nanoflowers-modified electrode had electrochemical properties similar to those of bare gold and platinum electrodes. It also exhibited significant electrocatalytic activities toward oxygen reduction.

Effects of (Ce, Cu) Co-doping on the Structural and Optical Properties of ZnO Aerogels Synthesized in Supercritical Ethanol

NASA Astrophysics Data System (ADS)

Djouadi, D.; Slimi, O.; Hammiche, L.; Chelouche, A.; Touam, T.

2018-03-01

Undoped, Ce-doped, Cu-doped and (Ce,Cu ) co-doped ZnO aerogels were synthesized by sol-gel process in supercritical conditions of ethanol. [Cu]/[Zn] and [Ce]/[Zn] atomic ratios were fixed at 0.02 (2%). The aerogels were investigated without any additional treatments by using X-ray diffraction (XRD), UV–visible spectrophotometry, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). XRD results revealed that all the samples are well crystallized in hexagonal wurtzite structure. EDS measurements showed that highly pure aerogels are prepared. SEM analysis indicated that the morphology of the samples is dependent on Cu and Ce dopants. From UV-visible spectroscopy analyses, it was shown that the absorption and the band gap of the aerogels are strongly affected by Ce and Cu dopants. FTIR spectra demonstrated that co-doping induces a shift of Zn-O bond vibration band toward low wavenumbers. The room temperature photoluminescence spectra put into evidence that the visible emission intensity is influenced by Ce and Cu doping. In particular, the co-doping leads to the appearance of a blue emission band at 443 nm.

Sulfur Nanoparticles Synthesis and Characterization from H2S Gas, Using Novel Biodegradable Iron Chelates in W/O Microemulsion

PubMed Central

2008-01-01

Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5–15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.

Hot Corrosion Behavior of Ti-48Al and Ti-48Al-2Cr Intermetallic Alloys Produced by Electric Current Activated Sintering

NASA Astrophysics Data System (ADS)

Garip, Y.; Ozdemir, O.

2018-06-01

In this study, Ti-48Al and Ti-48Al-2Cr (at. pct) intermetallic alloys were produced by electric current activated sintering (ECAS). In order to characterize the phase formation and microstructures of these alloys, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis were used. The XRD result shows that the intermetallic alloys are composed of γ-TiAl and α 2-Ti3Al phases. The microstructure is dense with a low amount of porosity. The hot corrosion behavior of intermetallic alloys was carried out in a salt mixture of 25 wt pct K2SO4 and 75 wt pct Na2SO4 at 700 °C for 180 hours. The morphology of corroded surfaces was observed by SEM-EDS and XRD. Corrosion phases were identified as TiO2 and Al2O3. Well-adhering oxide scale was detected on the corroded sample surface at the end of 180 hours, and no spallation was observed. In addition, a parabolic curve was obtained at the weight change rate vs time.

Multi scale imaging of the Cloudy Zone in the Tazewell IIICD Meteorite

NASA Astrophysics Data System (ADS)

Einsle, J. F.; Harrison, R. J.; Nichols, C. I. O.; Blukis, R.; Midgley, P. A.; Eggeman, A.; Saghi, Z.; Bagot, P.

2015-12-01

Paleomagnetic studies of iron and stony iron meteorites suggest that many small planetary bodies possessed molten cores resulting in the generation of a magnetic field. As these bodies cooled, Fe-Ni metal trapped within their mantle underwent a series of low-temperature transitions, leading to the familiar Widmanstatten intergrowth of kamacite and taenite. Adjacent to the kamacite/taenite interface is the so-called "cloudy zone" (CZ): a nanoscale intergrowth of tetrataenite islands in an Fe-rich matrix phase formed via spinodal decomposition. It has recently been shown (Bryson et al. 2015, Nature) that the CZ encodes a time-series record of the evolution of the magnetic field generated by the molten core of the planetary body. Extracting meaningful paleomagnetic data from the CZ relies, on a thorough understanding of the 3D chemical and magnetic properties of the intergrowth focsusing on the interactions between the magnetically hard tetrataenite islands and the magnetically soft matrix. Here we present a multi scale study of the chemical and crystallographic make up of the CZ in the Tazewell IIICD meteorite, using a range of advanced microscopy techniques. The results provide unprecedented insight into the architecture of the CZ, with implications for how the CZ acquires chemical transformation remanance during cooling on the parent body. Previous 2D transmission electron microscope studies of the CZ suggested that the matrix is an ordered Fe3Ni phase with the L12 structure. Interpretation of the electron diffraction patterns and chemical maps in these studies was hindered by a failure to resolve signals from overlapping island and matrix phases. Here we obtain high resolution electron diffraction and 3D chemical maps with near atomic resolution using a combination of scanning precession electron diffraction, 3D STEM EDS and atom probe tomography. Using this combined methodology we reslove for the first time the phenomena of secondary precipitation in the tetrataenite islands and chemical partitioning of trace elements between the island and matrix phases. The new crystallographic and compositional measurements present a quantitative picture of low-temperature local equilibrium in the Fe-Ni system. This leads to an improved understanding of the magnetic models used to perform paleomagnetism of the CZ.

Microstructural Examination of Oxidized Fe_(14-x) Nb5_x Alloy Produced from Powders Prepared by Mechanical Alloying

NASA Astrophysics Data System (ADS)

Demirkıran, A. Şükran; Sen, Saduman; Ozdemir, Ozkan; Sen, Ugur

In the present study, ferrous niobium, ferrous boron and iron were used as starting powders. The mixture of the powders which were calculated to give the designed compositions was prepared by using planetary high energy ball mill. Mechanically alloyed powders were pressed and sintered at 1350°C for 120 min in Ar atmosphere. The cyclic oxidation experiments were carried out in an electrical furnace at 650, 750 and 850 °C in open atmosphere for 96 h. The specimens were periodically weighed for the determination of weight change. Before and after oxidation, the present phases of the samples were determined by X-ray diffraction analysis (XRD). The microstructural characterizations were realized using scanning electron microscopy (SEM) with EDS attachment.

Microstructure and Mechanical Properties of C/C Composite/TC17 Joints with Ag-Cu-Ti Brazing Alloy

NASA Astrophysics Data System (ADS)

Cao, Xiujie; Zhu, Ying; Guo, Wei; Peng, Peng; Ma, Kaituo

2017-12-01

Carbon/Carbon composite(C/C) was vacuum brazed to titanium alloy (TC17) using Ag-Cu-Ti brazing alloy. The effects of brazing temperature on the interfacial microstructure and joint properties were investigated by energy dispersive spectrometer (EDS), a scanning electron microscope (SEM), X-ray diffraction (XRD) and Gleeble1500D testing machine. Results show that C/C composite and TC17 were successfully brazed using AgCuTi brazing alloy. Various phases including TiC, Ag(s, s), Cu(s, s), Ti3Cu4, TiCu, and Ti2Cu were formed in the brazed joint. The maximum shear strength of the brazed joints with AgCuTi brazing alloy was 24±1 MPa when brazed at 860°C for 15 min.

Ternary Precursors for Depositing I-III-VI2 Thin Films for Solar Cells via Spray CVD

NASA Technical Reports Server (NTRS)

Banger, K. K.; Hollingsworth, J. A.; Jin, M. H.-C.; Harris, J. D.; Duraj, S. A.; Smith, M.; Scheiman, D.; Bohannan, E. W.; Switzer, J. A.; Buhro, W. E.

2002-01-01

The development of thin-film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power (W/kg). Thin-film fabrication studies demonstrate that ternary single source precursors (SSP's) can be used in either a hot or cold-wall spray chemical vapour deposition (CVD) reactor, for depositing CuInS2, CuGaS2, and CuGaInS2 at reduced temperatures (400 to 450 C), which display good electrical and optical properties suitable for photovoltaic (PV) devices. X-ray diffraction studies, energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) confirmed the formation of the single phase CIS, CGS, CIGS thin-films on various substrates at reduced temperatures.

High-compactness coating grown by plasma electrolytic oxidation on AZ31 magnesium alloy in the solution of silicate-borax

NASA Astrophysics Data System (ADS)

Shen, M. J.; Wang, X. J.; Zhang, M. F.

2012-10-01

A ceramic coating was formed on the surface of AZ31 magnesium alloy by plasma electrolytic oxidation (PEO) in the silicate solution with and without borax doped. The composition, morphology, elements and roughness as well as mechanical property of the coating were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reciprocal-sliding tribometer. The results show that the PEO coating is mainly composed of magnesia. When using borax dope, boron element is permeating into the coating and the boron containing phase exist in the form of amorphous. In addition, the microhardness and compactness of the PEO coating are improved significantly due to doped borax.

Low temperature nucleation of Griffiths Phase in Co doped LaMnO3 nanostructures

NASA Astrophysics Data System (ADS)

Adeela, N.; Khan, U.; Naz, S.; Iqbal, M.; Irfan, M.; Cheng, Y.

2017-11-01

We have reported magnetic properties of La1-xCoxMnO3 nanostructures synthesized by hydrothermal route. The crystal structure has been characterized by X-ray diffraction (XRD) technique, which shows rhombohedral perovskite structure at room temperature. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) have been used to analyse morphology and chemical composition of prepared nanoparticles. Magnetic hysteresis loops of all the samples exhibit ferromagnetic behaviour at 10 K. Inverse susceptibility graphs as a function of temperature represent deviation from Curie Weiss law. The indication for short range ferromagnetic clusters well above Curie temperature is observed due to the Griffiths Phase (GP). It is proposed that the presence of GP arises from induced size effects of La and Co ions.

Synthesis of Bimetallic Platinum Nanoparticles for Biosensors

PubMed Central

Leteba, Gerard M.; Lang, Candace I.

2013-01-01

The use of magnetic nanomaterials in biosensing applications is growing as a consequence of their remarkable properties; but controlling the composition and shape of metallic nanoalloys is problematic when more than one precursor is required for wet chemistry synthesis. We have developed a successful simultaneous reduction method for preparation of near-spherical platinum-based nanoalloys containing magnetic solutes. We avoided particular difficulties in preparing platinum nanoalloys containing Ni, Co and Fe by the identification of appropriate synthesis temperatures and chemistry. We used transmission electron microscopy (TEM) to show that our particles have a narrow size distribution, uniform size and morphology, and good crystallinity in the as-synthesized condition. Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirms the coexistence of Pt with the magnetic solute in a face-centered cubic (FCC) solid solution. PMID:23941910

Oxidation of ZrB2-SiC

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Halbig, Michael C.

2001-01-01

In this paper the oxidation behavior of ZrB2-20 vol% SiC is examined. Samples were exposed in stagnant air in a zirconia furnace (Deltech, Inc.) at temperatures of 1327, 1627, and 1927 C for ten ten-minute cycles. Samples were removed from the furnace after one, five, and ten cycles. Oxidized material was characterized by mass change when possible, x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Oxidation kinetics, oxide scale development, and matrix recession were monitored as a function of time and temperature. Oxidation and recession rates of ZrB2 - 20 vol% SiC were adequately modeled by parabolic kinetics. Oxidation rates of this material are rapid, allowing only very short-term application in air or other high oxygen partial pressure environments.

Characterization of morphology and hydration products of high-volume fly ash paste by monochromatic scanning x-ray micro-diffraction (μ-SXRD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, Sungchul; Meral, Cagla; Department of Civil Engineering, Middle East Technical University, 06800 Ankara

2014-05-01

The present study focuses on identification and micro-structural characterization of the hydration products formed in high-volume fly ash (HVFA)/portland cement (PC) systems using monochromatic scanning x-ray micro-diffraction (μ-SXRD) and SEM-EDS. Pastes with up to 80% fly ash replacement were studied. Phase maps for HVFA samples using μ-SXRD patterns prove that μ-SXRD is an effective method to identify and visualize the distribution of phases in the matrix. μ-SXRD and SEM-EDS analysis shows that the C-S-H formed in HVFA system containing 50% or more of fly ash has a similar structure as C-S-H(I) with comparatively lower Ca/Si ratio than the one producedmore » in PC system. Moreover, coexistence of C-S-H(I) and strätlingite is observed in the system containing 80% of fly ash, confirming that the amount of alumina and silicate phases provided by the fly ash is a major factor for the formation of C-S-H(I) and strätlingite in HVFA system. - Highlights: • High-volume fly ash (HVFA) paste was studied by scanning x-ray micro-diffraction. • Coexistence of C-S-H(I) and strätlingite in the HVFA system is clearly shown. • The distribution of minor phases in the HVFA system is shown. • Differences between inner and outer products of fly ash are observed by SEM-EDS.« less

Attenuation of encrustation by self-assembled inorganic fullerene-like nanoparticles

NASA Astrophysics Data System (ADS)

Ron, Racheli; Zbaida, David; Kafka, Ilan Z.; Rosentsveig, Rita; Leibovitch, Ilan; Tenne, Reshef

2014-04-01

Ureteral stents and urethral catheters are commonly used medical devices for maintaining urinary flow. However, long-term placement (>30 days) of these devices in the urinary tracts is limited by the development of encrustation, a phenomenon that holds a prevalence of 50% within this patient population, resulting in a great deal of morbidity to the patients. Here we report the influence of surface coating of an all-silicone catheter with rhenium-doped fullerene-like molybdenum disulfide (Re:IF-MoS2) nanoparticles on the growth and attachment of in vitro encrustation stones. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) analyses indicated a remarkable attenuation in encrustation occupation on the Re:IF-MoS2-coated catheter surfaces compared to neat catheters. The doped nanoparticles displayed a unique tendency to self-assemble into mosaic-like arrangements, modifying the surface to be encrustation-repellent. The mechanism of encrustation retardation on the surface coated catheters is discussed in some detail. The ramification of these results for the clogging of other body indwelling devices is briefly discussed.Ureteral stents and urethral catheters are commonly used medical devices for maintaining urinary flow. However, long-term placement (>30 days) of these devices in the urinary tracts is limited by the development of encrustation, a phenomenon that holds a prevalence of 50% within this patient population, resulting in a great deal of morbidity to the patients. Here we report the influence of surface coating of an all-silicone catheter with rhenium-doped fullerene-like molybdenum disulfide (Re:IF-MoS2) nanoparticles on the growth and attachment of in vitro encrustation stones. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) analyses indicated a remarkable attenuation in encrustation occupation on the Re:IF-MoS2-coated catheter surfaces compared to neat catheters. The doped nanoparticles displayed a unique tendency to self-assemble into mosaic-like arrangements, modifying the surface to be encrustation-repellent. The mechanism of encrustation retardation on the surface coated catheters is discussed in some detail. The ramification of these results for the clogging of other body indwelling devices is briefly discussed. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06231g

Nanometres-resolution Kikuchi patterns from materials science specimens with transmission electron forward scatter diffraction in the scanning electron microscope.

PubMed

Brodusch, N; Demers, H; Gauvin, R

2013-04-01

A charge-coupled device camera of an electron backscattered diffraction system in a scanning electron microscope was positioned below a thin specimen and transmission Kikuchi patterns were collected. Contrary to electron backscattered diffraction, transmission electron forward scatter diffraction provides phase identification and orientation mapping at the nanoscale. The minimum Pd particle size for which a Kikuchi diffraction pattern was detected and indexed reliably was 5.6 nm. An orientation mapping resolution of 5 nm was measured at 30 kV. The resolution obtained with transmission electron forward scatter diffraction was of the same order of magnitude than that reported in electron nanodiffraction in the transmission electron microscope. An energy dispersive spectrometer X-ray map and a transmission electron forward scatter diffraction orientation map were acquired simultaneously. The high-resolution chemical, phase and orientation maps provided at once information on the chemical form, orientation and coherency of precipitates in an aluminium-lithium 2099 alloy. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Electron Diffraction Using Transmission Electron Microscopy

PubMed Central

Bendersky, Leonid A.; Gayle, Frank W.

2001-01-01

Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The advantages of electron diffraction over other methods, e.g., x-ray or neutron, arise from the extremely short wavelength (≈2 pm), the strong atomic scattering, and the ability to examine tiny volumes of matter (≈10 nm3). The NIST Materials Science and Engineering Laboratory has a history of discovery and characterization of new structures through electron diffraction, alone or in combination with other diffraction methods. This paper provides a survey of some of this work enabled through electron microscopy. PMID:27500060

Macroscopic and microscopic variation in recovered magnesium phosphate materials: implications for phosphorus removal processes and product re-use.

PubMed

Massey, Michael S; Ippolito, James A; Davis, Jessica G; Sheffield, Ron E

2010-02-01

Phosphorus (P) recovery and re-use will become increasingly important for water quality protection and sustainable nutrient cycling as environmental regulations become stricter and global P reserves decline. The objective of this study was to examine and characterize several magnesium phosphates recovered from actual wastewater under field conditions. Three types of particles were examined including crystalline magnesium ammonium phosphate hexahydrate (struvite) recovered from dairy wastewater, crystalline magnesium ammonium phosphate hydrate (dittmarite) recovered from a food processing facility, and a heterogeneous product also recovered from dairy wastewater. The particles were analyzed using "wet" chemical techniques, powder X-ray diffraction (XRD), and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy (SEM-EDS). The struvite crystals had regular and consistent shape, size, and structure, and SEM-EDS analysis clearly showed the struvite crystals as a surface precipitate on calcium phosphate seed material. In contrast, the dittmarite crystals showed no evidence of seed material, and were not regular in size or shape. The XRD analysis identified no crystalline magnesium phosphates in the heterogeneous product and indicated the presence of sand particles. However, magnesium phosphate precipitates on calcium phosphate seed material were observed in this product under SEM-EDS examination. These substantial variations in the macroscopic and microscopic characteristics of magnesium phosphates recovered under field conditions could affect their potential for beneficial re-use and underscore the need to develop recovery processes that result in a uniform, consistent product.

Nanorods, nanospheres, nanocubes: Synthesis, characterization and catalytic activity of nanoferrites of Mn, Co, Ni, Part-89

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Supriya; Srivastava, Pratibha; Singh, Gurdip, E-mail: gsingh4us@yahoo.com

2013-02-15

Graphical abstract: Prepared nanoferrites were characterized by FE-SEM and bright field TEM micrographs. The catalytic effect of these nanoferrites was evaluated on the thermal decomposition of ammonium perchlorate using TG and TG–DSC techniques. The kinetics of thermal decomposition of AP was evaluated using isothermal TG data by model fitting as well as isoconversional method. Display Omitted Highlights: ► Synthesis of ferrite nanostructures (∼20.0 nm) by wet-chemical method under different synthetic conditions. ► Characterization using XRD, FE-SEM, EDS, TEM, HRTEM and SAED pattern. ► Catalytic activity of ferrite nanostructures on AP thermal decomposition by thermal techniques. ► Burning rate measurements ofmore » CSPs with ferrite nanostructures. ► Kinetics of thermal decomposition of AP + nanoferrites. -- Abstract: In this paper, the nanoferrites of Mn, Co and Ni were synthesized by wet chemical method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive, X-ray spectra (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). It is catalytic activity were investigated on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG–DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + nanoferrites have also been investigated using isoconversional and model fitting approaches which have been applied to data for isothermal TG decomposition. The burning rate of CSPs was considerably enhanced by these nanoferrites. Addition of nanoferrites to AP led to shifting of the high temperature decomposition peak toward lower temperature. All these studies reveal that ferrite nanorods show the best catalytic activity superior to that of nanospheres and nanocubes.« less

Corrosion-induced microstructural developments in 316 stainless steel during exposure to molten Li2BeF4(FLiBe) salt

NASA Astrophysics Data System (ADS)

Zheng, Guiqiu; He, Lingfeng; Carpenter, David; Sridharan, Kumar

2016-12-01

The microstructural developments in the near-surface regions of AISI 316 stainless steel during exposure to molten Li2BeF4 (FLiBe) salt have been investigated with the goal of using this material for the construction of the fluoride salt-cooled high-temperature reactor (FHR), a leading nuclear reactor concept for the next generation nuclear plants (NGNP). Tests were conducted in molten FLiBe salt (melting point: 459 °C) at 700 °C in graphite crucibles and 316 stainless steel crucibles for exposure duration of up to 3000 h. Corrosion-induced microstructural changes in the near-surface regions of the samples were characterized using scanning electron microscopy (SEM) in conjunction with energy dispersive x-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM) with EDS capabilities. Intergranular corrosion attack in the near-surface regions was observed with associated Cr depletion along the grain boundaries. High-angle grain boundaries (15-180°) were particularly prone to intergranular attack and Cr depletion. The depth of attack extended to the depths of 22 μm after 3000-h exposure for the samples tested in graphite crucible, while similar exposure in 316 stainless steel crucible led to the attack depths of only about 11 μm. Testing in graphite crucibles led to the formation of nanometer-scale Mo2C, Cr7C3 and Al4C3 particle phases in the near-surface regions of the material. The copious depletion of Cr in the near-surface regions induced a γ-martensite to α-ferrite phase (FeNix) transformation. Based on the microstructural analysis, a thermal diffusion controlled corrosion model was developed and experimentally validated for predicting long-term corrosion attack depth.

TH-CD-202-01: BEST IN PHYSICS (JOINT IMAGING-THERAPY): Evaluation of the Use of Direct Electron Density CT Images in Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, T; Sun, B; Li, H

Purpose: The current standard for calculation of photon and electron dose requires conversion of Hounsfield Units (HU) to Electron Density (ED) by applying a calibration curve specifically constructed for the corresponding CT tube voltage. This practice limits the use of the CT scanner to a single tube voltage and hinders the freedom in the selection of optimal tube voltage for better image quality. The objective of this study is to report a prototype CT reconstruction algorithm that provides direct ED images from the raw CT data independently of tube voltages used during acquisition. Methods: A tissue substitute phantom was scannedmore » for Stoichiometric CT calibrations at tube voltages of 70kV, 80kV, 100kV, 120kV and 140kV respectively. HU images and direct ED images were acquired sequentially on a thoracic anthropomorphic phantom at the same tube voltages. Electron densities converted from the HU images were compared to ED obtained from the direct ED images. A 7-field treatment plan was made on all HU and ED images. Gamma analysis was performed to demonstrate quantitatively dosimetric change from the two schemes in acquiring ED. Results: The average deviation of EDs obtained from the direct ED images was −1.5%±2.1% from the EDs from HU images with the corresponding CT calibration curves applied. Gamma analysis on dose calculated on the direct ED images and the HU images acquired at the same tube voltage indicated negligible difference with lowest passing rate at 99.9%. Conclusion: Direct ED images require no CT calibration while demonstrate equivalent dosimetry compared to that obtained from standard HU images. The ability of acquiring direct ED images simplifies the current practice at a safer level by eliminating CT calibration and HU conversion from commissioning and treatment planning respectively. Furthermore, it unlocks a wider range of tube voltages in CT scanner for better imaging quality while maintaining similar dosimetric accuracy.« less

Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method.

PubMed

Jmal, Nouha; Bouaziz, Jamel

2017-02-01

In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO 2 14 CaO9 P 2 O 5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24MPa), Vickers hardness (214Hv), Young's modulus (52.3GPa), shear modulus (19GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co-Cr dental alloys.

PubMed

Li, Kai Chun; Prior, David J; Waddell, J Neil; Swain, Michael V

2015-12-01

The objective of this study was to identify the different microstructures produced by CC, PM and as-cast techniques for Co-Cr alloys and their phase stability following porcelain firings. Three bi-layer porcelain veneered Co-Cr specimens and one monolithic Co-Cr specimen of each alloy group [cast, powder metallurgy (PM), CAD/CAM (CC)] were manufactured and analyzed using electron backscatter diffraction (EBSD), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Specimens were treated to incremental numbers of porcelain firings (control 0, 5, 15) with crystallographic data, grain size and chemical composition subsequently obtained and analyzed. EBSD datasets of the cast alloy indicated large grains >200 μm whereas PM and CC alloy consisted of mean arithmetic grain sizes of 29.6 μm and 19.2 μm respectively. XRD and EBSD results both indicated the highest increase in hcp content (>13vol%) for cast Co-Cr alloy after treatment with porcelain firing while PM and CC indicated <2vol% hcp content. A fine grain interfacial layer developed on all surfaces of the alloy after porcelain firing. The depth of this layer increased with porcelain firings for as-cast and PM but no significant increase (p>.05) was observed in CC. EDS line scans indicated an increase in Cr content at the alloy surface after porcelain firing treatment for all three alloys. PM and CC produced alloy had superior fcc phase stability after porcelain firings compared to a traditional cast alloy. It is recommended that PM and CC alloys be used for porcelain-fused-to-metal restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of an emergency department-based electronic system for musculoskeletal consultation on facilitating care for common injuries.

PubMed

Mears, Simon C; Pantle, Hardin A; Bessman, Edward S; Lifchez, Scott D

2015-05-01

Access to musculoskeletal consultation in the emergency department (ED) is a nationwide problem. In addition, consultation from a subspecialist may be delayed or may not be available, which can slow down the ED flow and reduce patient satisfaction. The purpose of this study was to review the 1-year results of a change in the authors' institutional practice to reduce subspecialty consultation for select musculoskeletal problems while still ensuring adequate patient follow-up in orthopedic or plastic surgery clinics for patients not seen by these services in the ED. The authors hypothesized that select injuries could be safely managed in the ED by using an electronic system to ensure appropriate follow-up care. Using Kaizen methodology, a multidisciplinary group (including ED staff, orthopedics, plastic surgery, pediatrics, nursing, radiology, therapy, and administration) met to improve care for select musculoskeletal injuries. A system was agreed on in which ED providers managed select musculoskeletal injuries without subspecialist consultation. Follow-up was organized using an electronic system, which facilitated communication between the ED staff and the secretarial staff of the subspecialist departments. Over a 1-year period, 150 patients were treated using this system. Charts and radiographs were reviewed for missed injuries. Radiographic review revealed 2 missed injuries. One patient had additional back pain and a lumbar spine fracture was found during the subspecialist follow-up visit; it was treated nonoperatively. Another patient appeared to have scapholunate widening on the injury radiograph that was not appreciated in the ED. Of the 150 patients, 51 were seen in follow-up by a subspecialist at the authors' institution. An electronic system to organize follow-up with a subspecialist allowed the ED providers to deliver safe and effective care for simple musculoskeletal injuries. Copyright 2015, SLACK Incorporated.

Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes.

PubMed

Dalmora, Adilson C; Ramos, Claudete G; Oliveira, Marcos L S; Teixeira, Elba C; Kautzmann, Rubens M; Taffarel, Silvio R; de Brum, Irineu A S; Silva, Luis F O

2016-01-01

Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimize exposure to these natural fertilizing basalt dust wastes and is, thus, of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. Copyright © 2015 Elsevier B.V. All rights reserved.

Transient ischameic attack/stroke electronic decision support: a 14-month safety audit.

PubMed

Lavin, Timothy L; Ranta, Annemarei

2014-02-01

To assess the safety of a Transient Ischameic Attack (TIA)/Stroke Electronic Decision Support (EDS) tool in the primary care setting intended to aid general practitioners in the timely management of transient ischemic attacks (TIAs). A 14-month safety audit reviewing all patients managed with the help of the TIA/Stroke EDS tool. Major morbidity and mortality were assessed by screening patients for subsequent hospital admissions and investigating potential links to EDS use. Seventy-nine patients were managed with the aid of the TIA/Stroke EDS. EDS use resulted in 8 appropriate immediate hospital admissions because of patients being at high risk of stroke. Three patients had delayed admission, but care was fully guideline based and patients had no adverse outcome. Eleven admissions were unrelated to EDS use. Two deaths occurred; these did not result from inappropriate EDS advice. Results suggest that TIA/Stroke EDS use is not associated with major morbidity or mortality. Larger studies are needed to draw more definite conclusions regarding the utility of this TIA/Stroke EDS in preventing strokes. Copyright © 2014 National Stroke Association. All rights reserved.

Three-dimensional characterization of ODS ferritic steel using by FIB-SEM serial sectioning method.

PubMed

Endo, T; Sugino, Y; Ohono, N; Ukai, S; Miyazaki, N; Wang, Y; Ohnuki, S

2014-11-01

Considerable attention has been paid to the research of the electron tomography due to determine the three-dimensional (3D) structure of materials [1]. One of the electron tomography techniques, focused ion beam/scanning electron microscopy (FIB-SEM) imaging has advantages of high resolutions (10 nm), large area observation (μm order) and simultaneous energy dispersive x- ray microanalysis (EDS)/ electron backscatter diffraction (EBSD) analysis. The purpose of this study, three-dimensional EBSD analysis of ODS ferritic steel which carried out cold work using FIB-SEM equipment was conducted, and it aimed at analyzing the microstructure obtained there. The zone annealing tests were conducted for ferritic steel [2,3], which were produced through mechanical alloying and hot-extrusion. After zone annealing, specimens were mechanically polished with #400∼4000 emery paper, 1 µm diamond paste and alumina colloidal silica. The serial sectioning and the 3D-electron backscattering diffraction (3D-EBSD) analysis were carried out. We made the micro pillar (30 x 30 x 15 µm). The EBSD measurements were carried out in each layer after serial sectioning at a step size and milling depth was 80 nm with 30 slices. After EBSD analysis, the series of cross-sectional images were aligned according to arbitrarily specified areas and then stacked up to form a volume. Consequently, we obtained the 3D-IPF maps for ODS ferritic steel. In this specimen, the {111} and {001} grains are layered by turns. In addition, the volume fraction value of both plane are similar. The aspect ratio increases with specimen depth. The 3D-EBSD mapping is useful to analysis of the bulk material since this method obtain many microstructure information, such a shape, volume and orientation of the crystal, grain boundary. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Toward reliable and repeatable automated STEM-EDS metrology with high throughput

NASA Astrophysics Data System (ADS)

Zhong, Zhenxin; Donald, Jason; Dutrow, Gavin; Roller, Justin; Ugurlu, Ozan; Verheijen, Martin; Bidiuk, Oleksii

2018-03-01

New materials and designs in complex 3D architectures in logic and memory devices have raised complexity in S/TEM metrology. In this paper, we report about a newly developed, automated, scanning transmission electron microscopy (STEM) based, energy dispersive X-ray spectroscopy (STEM-EDS) metrology method that addresses these challenges. Different methodologies toward repeatable and efficient, automated STEM-EDS metrology with high throughput are presented: we introduce the best known auto-EDS acquisition and quantification methods for robust and reliable metrology and present how electron exposure dose impacts the EDS metrology reproducibility, either due to poor signalto-noise ratio (SNR) at low dose or due to sample modifications at high dose conditions. Finally, we discuss the limitations of the STEM-EDS metrology technique and propose strategies to optimize the process both in terms of throughput and metrology reliability.

Energy-resolved coherent diffraction from laser-driven electronic motion in atoms

NASA Astrophysics Data System (ADS)

Shao, Hua-Chieh; Starace, Anthony F.

2017-10-01

We investigate theoretically the use of energy-resolved ultrafast electron diffraction to image laser-driven electronic motion in atoms. A chirped laser pulse is used to transfer the valence electron of the lithium atom from the ground state to the first excited state. During this process, the electronic motion is imaged by 100-fs and 1-fs electron pulses in energy-resolved diffraction measurements. Simulations show that the angle-resolved spectra reveal the time evolution of the energy content and symmetry of the electronic state. The time-dependent diffraction patterns are further interpreted in terms of the momentum transfer. For the case of incident 1-fs electron pulses, the rapid 2 s -2 p quantum beat motion of the target electron is imaged as a time-dependent asymmetric oscillation of the diffraction pattern.

Investigation of Processing, Microstructures and Efficiencies of Polycrystalline CdTe Photovoltaic Films and Devices

NASA Astrophysics Data System (ADS)

Munshi, Amit Harenkumar

CdTe based photovoltaics have been commercialized at multiple GWs/year level. The performance of CdTe thin film photovoltaic devices is sensitive to process conditions. Variations in deposition temperatures as well as other treatment parameters have a significant impact on film microstructure and device performance. In this work, extensive investigations are carried out using advanced microstructural characterization techniques in an attempt to relate microstructural changes due to varying deposition parameters and their effects on device performance for cadmium telluride based photovoltaic cells deposited using close space sublimation (CSS). The goal of this investigation is to apply advanced material characterization techniques to aid process development for higher efficiency CdTe based photovoltaic devices. Several techniques have been used to observe the morphological changes to the microstructure along with materials and crystallographic changes as a function of deposition temperature and treatment times. Traditional device structures as well as advanced structures with electron reflector and films deposited on Mg1-xZnxO instead of conventional CdS window layer are investigated. These techniques include Scanning Electron Microscopy (SEM) with Electron Back Scattered Diffraction (EBSD) and Energy dispersive X-ray spectroscopy (EDS) to study grain structure and High Resolution Transmission Electron Microscopy (TEM) with electron diffraction and EDS. These investigations have provided insights into the mechanisms that lead to change in film structure and device performance with change in deposition conditions. Energy dispersive X-ray spectroscopy (EDS) is used for chemical mapping of the films as well as to understand interlayer material diffusion between subsequent layers. Electrical performance of these devices has been studied using current density vs voltage plots. Devices with efficiency over 18% have been fabricated on low cost commercial glass substrates with processes suitable for mass production. These are the highest efficiencies reported by any university or national laboratory for polycrystalline thin-film CdTe photovoltaics bettered only by researchers at First Solar Inc. Processing experiments are traditionally designed based on simulation results however in these study microscopic materials characterization has been used as the primary driving force to understand the effects of processing conditions. Every structure and efficiency reported in this study has been extensively studied using microscopic imaging and materials characterization and processing conditions accordingly altered to achieve higher efficiencies. Understanding CdCl2 passivation treatment out of this has been critical to this process. Several observations with regard to effect of CdCl 2 passivation have allowed the use to this treatment to achieve optimum performance. The effects of deposition temperature are also studied in rigorous details. All of these studies have played an important role in optimization of process that lead to high efficiency thin-film CdTe photovoltaic devices. An effort is made in this study to better understand and establish a 3-way relationship between processing conditions, film microstructure and device efficiency for sublimated thin-film CdTe photovoltaics. Some crucial findings include impact of grain size on efficiency of photovoltaic devices and improvement in fill-factor resulting from use of thicker CdTe absorber with larger grain size. An attempt is also made to understand the microstructure as the device efficiency improves from 1% efficiency to over 18% efficiency.

Ultrafast electron diffraction with megahertz MeV electron pulses from a superconducting radio-frequency photoinjector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, L. W.; Lin, L.; Huang, S. L.

We report ultrafast relativistic electron diffraction operating at the megahertz repetition rate where the electron beam is produced in a superconducting radio-frequency (rf) photoinjector. We show that the beam quality is sufficiently high to provide clear diffraction patterns from gold and aluminium samples. With the number of electrons, several orders of magnitude higher than that from a normal conducting photocathode rf gun, such high repetition rate ultrafast MeV electron diffraction may open up many new opportunities in ultrafast science.

Microwave synthesis and electrochemical characterization of Mn/Ni mixed oxide for supercapacitor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasankumar, T.; Jose, Sujin P., E-mail: sujamystica@yahoo.com; Ilangovan, R.

Nanostructured Mn/Ni mixed metal oxide was synthesized at ambient temperature by facile microwave irradiation technique. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray diffraction analysis confirmed the formation of Mn/Ni mixed oxide in rhombohedral phase and the grain size calculated was found to be 87 nm. The irregular spherical morphology of the prepared sample was exhibited by the SEM images. The characteristic peaks of FTIR at about 630 cm{sup −1} and 749 cm{sup −1} were attributed to the Mn-O and Ni-O stretching vibrations respectively. The presence of both Mn and Ni inmore » the prepared sample was validated by the EDS spectra which in turn confirmed the formation of mixed oxide. Cyclic voltammetry and galvanostatic chargedischarge measurements were employed to investigate the electrochemical performance of the mixed oxide. The cyclic voltammetry curves demonstrated good capacitive performance of the sample in the potential window −0.2V to 0.9V. The charge discharge study revealed the suitability of the prepared mixed oxide for the fabrication of supercapacitor electrode.« less

Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

NASA Astrophysics Data System (ADS)

Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

2018-04-01

Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

Transformation and Precipitation Kinetics in 30Cr10Ni Duplex Stainless Steel

NASA Astrophysics Data System (ADS)

Fazarinc, Matevz; Terčelj, Milan; Bombač, David; Kugler, Goran

2010-09-01

To improve the microstructure during casting, hot forming, and heat treatment of 30Cr10Ni duplex stainless steel, accurate data on the precipitation and transformation processes at high temperatures are needed. In this article, the precipitation and transformation processes at various aging times in the temperature range 873 K to 1573 K (600 °C to 1300 °C) were studied. The 30Cr10Ni ferrous alloy contains a relatively large amount of Cr, Ni, and C, which results in a complex microstructure. In addition to the ferrite, austenite, and sigma phase, the M23C6 and MC carbides were also observed in the microstructure. The precipitation of the sigma phase was observed after just 3 minutes of aging, and after 30 minutes of aging at approximately 1053 K (780 °C), its fraction exceeded 40 pct. An intensive austenite-to-ferrite transformation was observed above 1423 K (1150 °C). Optical microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD), as well as micro-indentation hardness, hardness, impact toughness, and tensile tests, were carried out to evaluate the obtained microstructures of aged samples.

Fabrication of chloroform sensor based on hydrothermally prepared low-dimensional β-Fe 2O 3 nanoparticles

NASA Astrophysics Data System (ADS)

Rahman, Mohammed M.; Jamal, A.; Khan, Sher Bahadar; Faisal, M.

2011-10-01

Hydrothermally prepared as-grown low-dimensional nano-particles (NPs) have been characterized using UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and electron dispersion spectroscopy (EDS). The uniformity of the nano-material was executed by the scanning electron microscopy, where the single phase of the nano-crystalline β-Fe 2O 3 was characterized using XRD techniques. β-Fe 2O 3 nanoparticles fabricated glassy carbon electrode (GCE) have improved chloroform-sensing performances in terms of electrical response ( I- V technique) for detecting analyte in liquid phase. The analytical performances were investigated, which showed that the better sensitivity, stability, and reproducibility of the sensor improved significantly by using Fe 2O 3 NPs thin-film on GCE. The calibration plot was linear ( R = 0.9785) over the large range of 12.0 μM to 12.0 mM. The sensitivity was calculated as 2.1792 μA cm -2 mM -1 with a detection limit of 4.4 ± 0.10 μM in short response time (10.0 s).

A study of the physical, chemical and biological properties of TiO2 coatings produced by micro-arc oxidation in a Ca-P-based electrolyte.

PubMed

dos Santos, Amanda; Araujo, Joyce R; Landi, Sandra M; Kuznetsov, Alexei; Granjeiro, José M; de Sena, Lidia Ágata; Achete, Carlos Alberto

2014-07-01

In this work, a porous and homogeneous titanium dioxide layer was grown on commercially pure titanium substrate using a micro-arc oxidation (MAO) process and Ca-P-based electrolyte. The structure and morphology of the TiO2 coatings were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, and profilometry. The chemical properties were studied using electron dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy. The wettability of the coating was evaluated using contact angle measurements. During the MAO process, Ca and P ions were incorporated into the oxide layer. The TiO2 coating was composed of a mixture of crystalline and amorphous structures. The crystalline part of the sample consisted of a major anatase phase and a minor rutile phase. A cross-sectional image of the coating-substrate interface reveals the presence of voids elongated along the interface. An osteoblast culture was performed to verify the cytocompatibility of the anodized surface. The results of the cytotoxicity tests show satisfactory cell viability of the titanium dioxide films produced in this study.

Mesoporous MnO2/carbon aerogel composites as promising electrode materials for high-performance supercapacitors.

PubMed

Li, Gao-Ren; Feng, Zhan-Ping; Ou, Yan-Nan; Wu, Dingcai; Fu, Ruowen; Tong, Ye-Xiang

2010-02-16

MnO(2) as one of the most promising candidates for electrochemical supercapacitors has attracted much attention because of its superior electrochemical performance, low cost, and environmentally benign nature. In this Letter, we explored a novel route to prepare mesoporous MnO(2)/carbon aerogel composites by electrochemical deposition assisted by gas bubbles. The products were characterized by energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The MnO(2) deposits are found to have high purity and have a mesoporous structure that will optimize the electronic and ionic conductivity to minimize the total resistance of the system and thereby maximize the performance characteristics of this material for use in supercapacitor electrodes. The results of nitrogen adsorption-desorption experiments and electrochemical measurements showed that these obtained mesoporous MnO(2)/carbon aerogel composites had a large specific surface area (120 m(2)/g), uniform pore-size distribution (around 5 nm), high specific capacitance (515.5 F/g), and good stability over 1000 cycles, which give these composites potential application as high-performance supercapacitor electrode materials.

On the transferability of electron density in binary vanadium borides VB, V3B4 and VB2.

PubMed

Terlan, Bürgehan; Akselrud, Lev; Baranov, Alexey I; Borrmann, Horst; Grin, Yuri

2015-12-01

Binary vanadium borides are suitable model systems for a systematic analysis of the transferability concept in intermetallic compounds due to chemical intergrowth in their crystal structures. In order to underline this structural relationship, topological properties of the electron density in VB, V3B4 and VB2 reconstructed from high-resolution single-crystal X-ray diffraction data as well as derived from quantum chemical calculations, are analysed in terms of Bader's Quantum Theory of Atoms in Molecules [Bader (1990). Atoms in Molecules: A Quantum Theory, 1st ed. Oxford: Clarendon Press]. The compounds VB, V3B4 and VB2 are characterized by a charge transfer from the metal to boron together with two predominant atomic interactions, the shared covalent B-B interactions and the polar covalent B-M interactions. The resembling features of the crystal structures are well reflected by the respective B-B interatomic distances as well as by ρ(r) values at the B-B bond critical points. The latter decrease with an increase in the corresponding interatomic distances. The B-B bonds show transferable electron density properties at bond critical points depending on the respective bond distances.

A measurement of electron-wall interactions using transmission diffraction from nanofabricated gratings

NASA Astrophysics Data System (ADS)

Barwick, Brett; Gronniger, Glen; Yuan, Lu; Liou, Sy-Hwang; Batelaan, Herman

2006-10-01

Electron diffraction from metal coated freestanding nanofabricated gratings is presented, with a quantitative path integral analysis of the electron-grating interactions. Electron diffraction out to the 20th order was observed indicating the high quality of our nanofabricated gratings. The electron beam is collimated to its diffraction limit with ion-milled material slits. Our path integral analysis is first tested against single slit electron diffraction, and then further expanded with the same theoretical approach to describe grating diffraction. Rotation of the grating with respect to the incident electron beam varies the effective distance between the electron and grating bars. This allows the measurement of the image charge potential between the electron and the grating bars. Image charge potentials that were about 15% of the value for that of a pure electron-metal wall interaction were found. We varied the electron energy from 50to900eV. The interaction time is of the order of typical metal image charge response times and in principle allows the investigation of image charge formation. In addition to the image charge interaction there is a dephasing process reducing the transverse coherence length of the electron wave. The dephasing process causes broadening of the diffraction peaks and is consistent with a model that ascribes the dephasing process to microscopic contact potentials. Surface structures with length scales of about 200nm observed with a scanning tunneling microscope, and dephasing interaction strength typical of contact potentials of 0.35eV support this claim. Such a dephasing model motivated the investigation of different metallic coatings, in particular Ni, Ti, Al, and different thickness Au-Pd coatings. Improved quality of diffraction patterns was found for Ni. This coating made electron diffraction possible at energies as low as 50eV. This energy was limited by our electron gun design. These results are particularly relevant for the use of these gratings as coherent beam splitters in low energy electron interferometry.

Characterization of ZnAl cast alloys with Na addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gancarz, Tomasz, E-mail: t.gancarz@imim.pl; Cempura, Grzegorz; Skuza, Wojciech

2016-01-15

This study was aimed at evaluating the microstructural change and thermal, electrical and mechanical properties with the addition of Na to eutectic ZnAl alloys. Solders based on eutectic ZnAl containing 0.2 to 3.0 (wt.%) of Na were developed for high temperature solder. Differential scanning calorimetry (DSC) measurements were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed over − 50 °C to 300 °C and 30 °C to 300 °C temperature ranges, respectively. The microstructure of the specimens was analyzed using scanning (SEM) and transmission electron microscopy (TEM) techniques. Chemical microanalysismore » was performed by energy-dispersive X-ray spectroscopy (EDS) on SEM and TEM. The precipitates of NaZn{sub 13} were confirmed by X-ray diffraction (XRD) measurements and selected area electron diffraction (SAED) techniques. The addition of Na to eutectic ZnAl alloy increased the electrical resistivity and reduced the coefficient of thermal expansion; however, the melting point did not change. The mechanical properties, strain and microhardness increased with Na content in alloys. - Highlights: • High temperature soldering materials of ZnAl with Na were designed and characterized. • Precipitates of NaZn{sub 13}were observed and confirmed using TEM and XRD. • Addition of Na to eutectic ZnAl cussed increased mechanical properties. • NaZn{sub 13} caused increased electrical resistivity and microhardness, and reduced the CTE.« less

Ethnographic analysis on the use of the electronic medical record for clinical handoff.

PubMed

Nelson, Philippa; Bell, Anthony J; Nathanson, Larry; Sanchez, Leon D; Fisher, Jonathan; Anderson, Philip D

2017-12-01

The objective of this study was to understand the social elements of clinical and organizational interactions of the key stakeholders in the specific context of an electronic dashboard used by the emergency department (ED) and inpatient medicine teams at the time of clinical referral and handover. An electronic handover function is utilised at the ED-inpatient interface at this institution and has given clinicians the ability to better communicate, monitor the department and strive to improve patient safety in streamline the delivery of care in the acute phase. This study uses an ethnographic qualitative research design incorporating semistructured interviews, participant observation on the ED floor and fieldwork notes. The setting for this research was in the ED at a tertiary University affiliated hospital. Triangulation was used to combine information obtained from multiple sources and information from fieldwork and interviews refined into useable chunks culminating in a thematic analysis. Thematic analysis yielded five central themes that reflected how the clinical staff utilised this IT system and why it had become embedded in the culture of clinical referral and handover. Efficient time management for improved patient flow was demonstrated, value added communication (at the interpersonal level), the building trust at the ED-inpatient interface, the maintenance of mutual respect across medical cultures and an overall enhancement of the quality of ED communication (in terms of the information available). A robust electronic handover process, resulted in an integrated approach to patient care by removing barriers to admission for medical inpatients, admitted via ED. The value proposition for patients was a more complete information transfer, both within the ED and between departments.

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites

PubMed Central

Li, Feng; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao

2018-01-01

Biomaterial composites made of titanium and hydroxyapatite (HA) powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD), back scattered electron imaging (BSE), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca3(PO4)2, TixPy, and Ti3O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed. PMID:29659504

Microstructure and Mechanical Properties of Graphene-Reinforced Titanium Matrix/Nano-Hydroxyapatite Nanocomposites.

PubMed

Li, Feng; Jiang, Xiaosong; Shao, Zhenyi; Zhu, Degui; Zhu, Minhao

2018-04-16

Biomaterial composites made of titanium and hydroxyapatite (HA) powder are among the most important biomedicalmaterials due to their good mechanical properties and biocompatibility. In this work, graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites were prepared by vacuum hot-pressing sintering. The microstructure and mechanical properties of graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were systematically investigated. Microstructures of the nanocomposites were examined by X-ray diffraction (XRD), back scattered electron imaging (BSE), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), electron probe microanalyzer (EPMA), and transmission electron microscope (TEM). The mechanical properties were determined from microhardness, shear strength, and compressive strength. Results showed that during the high-temperature sintering process, complex chemical reactions occurred, resulting in new phases of nucleation such as Ca₃(PO₄)₂, Ti x P y , and Ti₃O.The new phases, which easily dropped off under the action of external force, could hinder the densification of sintering and increase the brittleness of the nanocomposites. Results demonstrated that graphene had an impact on the microstructure and mechanical properties of the nanocomposites. Based on the mechanical properties and microstructure of the nanocomposites, the strengthening and fracture mechanisms of the graphene-reinforced titanium matrix/nano-hydroxyapatite nanocomposites with different graphene content were analyzed.

Microstructural Architecture, Microstructures, and Mechanical Properties for a Nickel-Base Superalloy Fabricated by Electron Beam Melting

NASA Astrophysics Data System (ADS)

Murr, L. E.; Martinez, E.; Gaytan, S. M.; Ramirez, D. A.; Machado, B. I.; Shindo, P. W.; Martinez, J. L.; Medina, F.; Wooten, J.; Ciscel, D.; Ackelid, U.; Wicker, R. B.

2011-11-01

Microstructures and a microstructural, columnar architecture as well as mechanical behavior of as-fabricated and processed INCONEL alloy 625 components produced by additive manufacturing using electron beam melting (EBM) of prealloyed precursor powder are examined in this study. As-fabricated and hot-isostatically pressed ("hipped") [at 1393 K (1120 °C)] cylinders examined by optical metallography (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive (X-ray) spectrometry (EDS), and X-ray diffraction (XRD) exhibited an initial EBM-developed γ″ (bct) Ni3Nb precipitate platelet columnar architecture within columnar [200] textured γ (fcc) Ni-Cr grains aligned in the cylinder axis, parallel to the EBM build direction. Upon annealing at 1393 K (1120 °C) (hot-isostatic press (HIP)), these precipitate columns dissolve and the columnar, γ, grains recrystallized forming generally equiaxed grains (with coherent {111} annealing twins), containing NbCr2 laves precipitates. Microindentation hardnesses decreased from 2.7 to 2.2 GPa following hot-isostatic pressing ("hipping"), and the corresponding engineering (0.2 pct) offset yield stress decreased from 0.41 to 0.33 GPa, while the UTS increased from 0.75 to 0.77 GPa. However, the corresponding elongation increased from 44 to 69 pct for the hipped components.

Digital electron diffraction – seeing the whole picture

PubMed Central

Beanland, Richard; Thomas, Paul J.; Woodward, David I.; Thomas, Pamela A.; Roemer, Rudolf A.

2013-01-01

The advantages of convergent-beam electron diffraction for symmetry determination at the scale of a few nm are well known. In practice, the approach is often limited due to the restriction on the angular range of the electron beam imposed by the small Bragg angle for high-energy electron diffraction, i.e. a large convergence angle of the incident beam results in overlapping information in the diffraction pattern. Techniques have been generally available since the 1980s which overcome this restriction for individual diffracted beams, by making a compromise between illuminated area and beam convergence. Here a simple technique is described which overcomes all of these problems using computer control, giving electron diffraction data over a large angular range for many diffracted beams from the volume given by a focused electron beam (typically a few nm or less). The increase in the amount of information significantly improves the ease of interpretation and widens the applicability of the technique, particularly for thin materials or those with larger lattice parameters. PMID:23778099

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS₂ Nanoparticles.

PubMed

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev; Tenne, Reshef

2018-02-26

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS₂ (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end.

Preparation and Optical Properties of CuS Nanofilms by a Facile Two-Step Process

NASA Astrophysics Data System (ADS)

Cui, Zhankui; Zhou, Junqiang; Ge, Suxiang; Zhao, Hongxiao

CuS nanofilms were prepared by a facile two-step process including chemical bath deposition of Cu nanofilms first and the subsequent thermal sulfuration step. The composition and structure of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The optical properties of CuS nanofilms were determined by Ultraviolet-visible (UV-Vis) technique. The results show that the nanofilms composed by Cu spherical nanoparticles were completely transformed to the nanofilms composed by CuS nanosheets when the sulfuration temperature was 350∘C. The light absorption edges of CuS nanofilms exhibit red shift when sulfuration occurred at lower temperature. A plausible growth mechanism related with gas phase reaction for formation of CuS nanofilms was also proposed.

Construction of super - hydrophobic copper alloy surface by one - step mixed solution immersion method

NASA Astrophysics Data System (ADS)

Gu, Qiang; Chen, Ying; Chen, Dong; Zhang, Zeting

2018-01-01

This paper presents a method for preparing a super hydrophobic surface with a fast, simple, low-cost, one-step reaction by immersing copper alloy in an ethanol solution containing silver nitrate and myristic acid. The effects of reaction time, reaction temperature, reactant concentration and reaction time on the wettability of the material were studied. The surface wettability, appearance, chemical composition, durability and chemical stability of the prepared samples was measured by water contact angle (CA), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results show that when the reaction time is only 10min, the surface WCA of the prepared material can reach 154.9. This study provides an effective method for the rapid preparation of stable super hydrophobic surfaces.

The lateritic profile of Balkouin, Burkina Faso: Geochemistry, mineralogy and genesis

NASA Astrophysics Data System (ADS)

Giorgis, Ilaria; Bonetto, Sabrina; Giustetto, Roberto; Lawane, Abdou; Pantet, Anne; Rossetti, Piergiorgio; Thomassin, Jean-Hugues; Vinai, Raffaele

2014-02-01

This study reports on the geochemical and mineralogical characterization of a lateritic profile cropping out in the Balkouin area, Central Burkina Faso, aimed at obtaining a better understanding of the processes responsible for the formation of the laterite itself and the constraints to its development. The lateritic profile rests on a Paleoproterozoic basement mostly composed of granodioritic rocks related to the Eburnean magmatic cycle passing upwards to saprolite and consists of four main composite horizons (bottom to top): kaolinite and clay-rich horizons, mottled laterite and iron-rich duricrust. In order to achieve such a goal, a multi-disciplinary analytical approach was adopted, which includes inductively coupled plasma (ICP) atomic emission and mass spectrometries (ICP-AES and ICP-MS respectively), X-ray powder diffraction (XRPD), scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and micro-Raman spectroscopy.

Insitu grown superhydrophobic Zn-Al layered double hydroxides films on magnesium alloy to improve corrosion properties

NASA Astrophysics Data System (ADS)

Zhou, Meng; Pang, Xiaolu; Wei, Liang; Gao, Kewei

2015-05-01

A hierarchical superhydrophobic zinc-aluminum layered double hydroxides (Zn-Al LDHs) film has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method following chemical modification. The characteristics of the films were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectroscopy (EDS). XRD patterns and SEM images showed that the micro/nanoscale hierarchical LDHs film surfaces composed of ZnO nanorods and Zn-Al LDHs nanowalls structures. The static contact angle (CA) for the prepared surfaces was observed at around 165.6°. The corrosion resistance of the superhydrophobic films was estimated by electrochemical impedance spectroscopy (EIS) and potentiondynamic polarization measurement. EIS and polarization measurements revealed that the superhydrophobic Zn-Al LDHs coated magnesium alloy had better corrosion resistance in neutral 3.5 wt.% NaCl solution.

Amino Acid Contents of Meteorite Mineral Separates

NASA Technical Reports Server (NTRS)

Berger, E. L.; Burton, A. S; Locke, D.

2017-01-01

Indigenous amino acids have been found indigenous all 8 carbonaceous chondrite groups. However, the abundances, structural, enantiomeric and isotopic compositions of amino acids differ significantly among meteorites of different groups and petrologic types. This suggests that parent-body conditions (thermal or aqueous alteration), mineralogy, and the preservation of amino acids are linked. Previously, elucidating specific relationships between amino acids and mineralogy was not possible because the samples analyzed for amino acids were much larger than the scale at which petrologic heterogeneity is observed (sub mm-scale differences corresponding to sub-mg samples). Recent advances in amino acid measurements and application of techniques such as high resolution X-ray diffraction (HR-XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) for mineralogical characterizations allow us to perform coordinated analyses on the scale at which mineral heterogeneity is observed.

Characterization of Laves phase in Crofer 22 H stainless steel.

PubMed

Hsiao, Zheng-Wen; Kuhn, Bernd; Chen, Delphic; Singheiser, Lorenz; Kuo, Jui-Chao; Lin, Dong-Yih

2015-07-01

This study investigated the effect of annealing temperature on the precipitation behavior of Crofer(®) 22 H at 600°C, 700°C, and 800°C. The grain size distribution, precipitate phase identification, and microstructure were analyzed using electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDS). The morphology of Laves phase (Fe,Cr,Si)(2)(Nb,W) precipitates having the Cr(2)Nb structure changed from strip-like to needle-shaped as the annealing temperature was increased. The precipitates of the Laves phase also shifted from the grain boundaries to the grain interiors when the temperature was increased. However, the average grain size (150 μm) of the ferritic matrix did not significantly change at 600°C, 700°C, and 800°C for 10 h. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photocatalytic Performance of a Novel MOF/BiFeO₃ Composite.

PubMed

Si, Yunhui; Li, Yayun; Zou, Jizhao; Xiong, Xinbo; Zeng, Xierong; Zhou, Ji

2017-10-10

In this study, MOF/BiFeO₃ composite (MOF, metal-organic framework) has been synthesized successfully through a one-pot hydrothermal method. The MOF/BiFeO₃ composite samples, pure MOF samples and BiFeO₃ samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and by UV-vis spectrophotometry. The results and analysis reveal that MOF/BiFeO₃ composite has better photocatalytic behavior for methylene blue (MB) compared to pure MOF and pure BiFeO₃. The enhancement of photocatalytic performance should be due to the introduction of MOF change the surface morphology of BiFeO 3, which will increase the contact area with MB. This composing strategy of MOF/BiFeO₃ composite may bring new insight into the designing of highly efficient photocatalysts.

Microstructure and mechanical behavior of metal injection molded Ti-Nb binary alloys as biomedical material.

PubMed

Zhao, Dapeng; Chang, Keke; Ebel, Thomas; Qian, Ma; Willumeit, Regine; Yan, Ming; Pyczak, Florian

2013-12-01

The application of titanium (Ti) based biomedical materials which are widely used at present, such as commercially pure titanium (CP-Ti) and Ti-6Al-4V, are limited by the mismatch of Young's modulus between the implant and the bones, the high costs of products, and the difficulty of producing complex shapes of materials by conventional methods. Niobium (Nb) is a non-toxic element with strong β stabilizing effect in Ti alloys, which makes Ti-Nb based alloys attractive for implant application. Metal injection molding (MIM) is a cost-efficient near-net shape process. Thus, it attracts growing interest for the processing of Ti and Ti alloys as biomaterial. In this investigation, metal injection molding was applied to the fabrication of a series of Ti-Nb binary alloys with niobium content ranging from 10wt% to 22wt%, and CP-Ti for comparison. Specimens were characterized by melt extraction, optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Titanium carbide formation was observed in all the as-sintered Ti-Nb binary alloys but not in the as-sintered CP-Ti. Selected area electron diffraction (SAED) patterns revealed that the carbides are Ti2C. It was found that with increasing niobium content from 0% to 22%, the porosity increased from about 1.6% to 5.8%, and the carbide area fraction increased from 0% to about 1.8% in the as-sintered samples. The effects of niobium content, porosity and titanium carbides on mechanical properties have been discussed. The as-sintered Ti-Nb specimens exhibited an excellent combination of high tensile strength and low Young's modulus, but relatively low ductility. © 2013 Elsevier Ltd. All rights reserved.

Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

NASA Astrophysics Data System (ADS)

Pavithradevi, S.; Suriyanarayanan, N.; Boobalan, T.

2017-03-01

Nanocrystalline copper ferrite CuFe2O4 is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe2O4 is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe2O4 nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm-1 and 4000 cm-1. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25-34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field.

Structural, optical and dielectric investigation of CdFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Sagadevan, Suresh; Pal, Kaushik; Zaman Chowdhury, Zaira; Enamul Hoque, Md

2017-07-01

A simple thermal decomposition technique has been executed for the synthesis of cadmium ferrite (CdFe2O4) nanoparticles. With the help of x-ray diffraction; scanning electron microscopy, energy-dispersive x-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy the prepared nanoparticles were identified. The crystal size of the average particles aggregated and was found approximately to be 10-14 nm by means of XRD studies. However, the results of high-resolution transmission electron microscopy (HR-TEM) investigation ensured distinguished nanoparticles, and also the polycrystalline nature of those nanoparticles was confirmed by selected area diffraction (SAED) patterns. The scanning electron microscopy (SEM) images explored a random distribution of grains within the sample. Thin film surface topology of roughness and surface current measurement were studied by atomic force microscopy (TP-AFM, C-AFM). Hence, from the ultraviolet-visible (UV) spectroscopic absorption illustrated significant optical properties. Moreover, the optical energy band gap (E g) of CdFe2O4 nanoparticle was determined to be 1.74 eV. By studying the variation of dielectric constant and dielectric loss with respect to frequency, the CdFe2O4 nanoparticles electrical properties were analyzed. Analysis in the real and imaginary part of impedance explained their frequency and temperature dependence of the CdFe2O4 nanoparticles. The traditional solution-phase organometallic approach provides an effective way to synthesize high quality hydrophobic semiconductor-CdFe2O4 nanoparticles. Our simple, cost-effective approach is quite general, which is applicable to other nanomaterials, and it utilizes the currently mature in Nano-chemistry. The nanocomposite assemblies’ exhibit strong anisotropic optical and electrical properties are open up new possibilities in remarkable applications for optoelectronics in the near future.

Self catalytic growth of indium oxide (In2O3) nanowires by resistive thermal evaporation.

PubMed

Kumar, R Rakesh; Rao, K Narasimha; Rajanna, K; Phani, A R

2014-07-01

Self catalytic growth of Indium Oxide (In2O3) nanowires (NWs) have been grown by resistive thermal evaporation of Indium (In) in the presence of oxygen without use of any additional metal catalyst. Nanowires growth took place at low substrate temperature of 370-420 degrees C at an applied current of 180-200 A to the evaporation boat. Morphology, microstructures, and compositional studies of the grown nanowires were performed by employing field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) respectively. Nanowires were uniformly grown over the entire Si substrate and each of the nanowire is capped with a catalyst particle at their end. X-ray diffraction study reveals the crystalline nature of the grown nanowires. Transmission electron microscopy study on the nanowires further confirmed the single crystalline nature of the nanowires. Energy dispersive X-ray analysis on the nanowires and capped nanoparticle confirmed that Indium act as catalyst for In2O3 nanowires growth. A self catalytic Vapor-Liquid-Solid (VLS) growth mechanism was responsible for the growth of In2O3 nanowires. Effect of oxygen partial pressure variation and variation of applied currents to the evaporation boat on the nanowires growth was systematically studied. These studies concluded that at oxygen partial pressure in the range of 4 x 10(-4), 6 x 10(-4) mbar at applied currents to the evaporation boat of 180-200 A were the best conditions for good nanowires growth. Finally, we observed another mode of VLS growth along with the standard VLS growth mode for In2O3 nanowires similar to the growth mechanism reported for GaAs nanowires.

Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fabbro, Maria T.; Department of Inorganic and Organic Chemistry, Universitat Jaume I, Campus del Riu Sec, E-12071 Castellón; Gracia, Lourdes

Ag{sub 2}CrO{sub 4} microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag{sub 2}CrO{sub 4} microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of themore » optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO{sub 6}] and [AgO{sub 4}] clusters, generating ideal conditions for the growth of Ag nanoparticles. - Graphical abstract: Theoretical representation of the Ag{sub 2}CrO{sub 4} orthorhombic structure. Display Omitted - Highlights: • The Ag{sub 2}CrO{sub 4} microcrystals indicate an orthorhombic structure. • The formation of Ag{sup 0} promotes Ag-nanoparticle growth on the surface of the Ag{sub 2}CrO{sub 4}. • Electron irradiation of the material induces the formation of Ag vacancies.« less

Effect of a novel load-bearing trabecular Nitinol scaffold on rabbit radius bone regeneration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il; National Research Tomsk Polytechnic University, Tomsk, 634050

The research aim was to evaluate the bone regeneration capability of novel load-bearing NiTi alloy (Nitinol) scaffolds in a critical-size defect (CSD) model. High strength “trabecular Nitinol” scaffolds were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) annealing of the highly porous Ni foam in Ti powder at 900°C. This was followed by PIRAC nitriding to mitigate the release of potentially toxic Ni ions. Scaffolds phase composition and microstructure were characterized by X-ray diffraction and scanning electron microscopy (SEM/EDS), and their mechanical properties were tested in compression. New Zealand white rabbits received bone defect in right radius and were dividedmore » in four groups randomly. In the control group, nothing was placed in the defect. In other groups, NiTi scaffolds were implanted in the defect: (i) as produced, (ii) loaded with bone marrow aspirate (BMA), and (iii) biomimetically CaP-coated. The animals were sacrificed after 12 weeks. The forelimbs with scaffolds were resected, fixed, sectioned and examined in SEM. New bone formation inside the scaffold was studied by EDS analysis and by the processing of backscattered electron images. Bone ingrowth into the scaffold was observed in all implant groups, mostly next to the ulna. New bone formation was strongly enhanced by BMA loading and biomimeatic CaP coating, the bone penetrating as much as 1–1.5 mm into the scaffold. The results of this preliminary study demonstrate that the newly developed high strength trabecular Nitinol scaffolds can be successfully used for bone regeneration in critical size defects.« less

Synthesis, dielectric, conductivity and magnetic studies of LiNi1/3Co1/3Mn(1/3)-xAlxO2 (x = 0.0, 0.02, 0.04 and 0.06) for cathode materials of lithium-ion batteries

NASA Astrophysics Data System (ADS)

Murali, N.; Margarette, S. J.; Veeraiah, V.

Layered structure cathode materials LiNi1/3Co1/3Mn(1/3)-xAlxO2 (x = 0.0, 0.02, 0.04 and 0.06) are prepared by the sol-gel method by adding citric acid as chelating agent. The physical, electrical and magnetic properties of the synthesized materials are systematically discussed using the structural (XRD, FESEM with EDS and FT-IR), impedance (LCR) and electron spin resonance (ESR) measurements. The X-ray diffraction pattern of the synthesized samples possessed the α-NaFeO2 structure of the space group, R 3 bar m , with no evidence of any impurities. The peak intensity ratio I(104)/I(003) increased with Al concentration, which indicated the cation mixing between transition metal layer and lithium layer. The field effect scanning electron microscopy showed the particle size distribution in the range of 230-250 nm and EDS has been analysed for elemental mapping. The local structure is investigated by vibrational spectroscopy in FT-IR study. The impedance studies are characterized by complex impedance spectroscopy (CIS) in the frequency range from 42 Hz to 1 MHz at room temperature (30 °C). The dielectric properties are analyzed in the framework of complex dielectric permittivity and formalism of the complex electric modulus. For these samples, the ESR analysis of magnetic measurements, the degree of cation mixing, is estimated to be Ni2+(3b) = 2.75%.

Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika

Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffractionmore » (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.« less

X-Ray Sum Frequency Diffraction for Direct Imaging of Ultrafast Electron Dynamics

NASA Astrophysics Data System (ADS)

Rouxel, Jérémy R.; Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul

2018-06-01

X-ray diffraction from molecules in the ground state produces an image of their charge density, and time-resolved x-ray diffraction can thus monitor the motion of the nuclei. However, the density change of excited valence electrons upon optical excitation can barely be monitored with regular diffraction techniques due to the overwhelming background contribution of the core electrons. We present a nonlinear x-ray technique made possible by novel free electron laser sources, which provides a spatial electron density image of valence electron excitations. The technique, sum frequency generation carried out with a visible pump and a broadband x-ray diffraction pulse, yields snapshots of the transition charge densities, which represent the electron density variations upon optical excitation. The technique is illustrated by ab initio simulations of transition charge density imaging for the optically induced electronic dynamics in a donor or acceptor substituted stilbene.

Relativistic electron diffraction at the UCLA Pegasus photoinjector laboratory.

PubMed

Musumeci, P; Moody, J T; Scoby, C M

2008-10-01

Electron diffraction holds the promise to yield real-time resolution of atomic motion in an easily accessible environment like a university laboratory at a fraction of the cost of fourth-generation X-ray sources. Currently the limit in time-resolution for conventional electron diffraction is set by how short an electron pulse can be made. A very promising solution to maintain the highest possible beam intensity without excessive pulse broadening from space charge effects is to increase the electron energy to the MeV level where relativistic effects significantly reduce the space charge forces. Rf photoinjectors can in principle deliver up to 10(7)-10(8) electrons packed in bunches of approximately 100-fs length, allowing an unprecedented time resolution and enabling the study of irreversible phenomena by single-shot diffraction patterns. The use of rf photoinjectors as sources for ultrafast electron diffraction has been recently at the center of various theoretical and experimental studies. The UCLA Pegasus laboratory, commissioned in early 2007 as an advanced photoinjector facility, is the only operating system in the country, which has recently demonstrated electron diffraction using a relativistic beam from an rf photoinjector. Due to the use of a state-of-the-art ultrashort photoinjector driver laser system, the beam has been measured to be sub-100-fs long, at least a factor of 5 better than what measured in previous relativistic electron diffraction setups. Moreover, diffraction patterns from various metal targets (titanium and aluminum) have been obtained using the Pegasus beam. One of the main laboratory goals in the near future is to fully develop the rf photoinjector-based ultrafast electron diffraction technique with particular attention to the optimization of the working point of the photoinjector in a low-charge ultrashort pulse regime, and to the development of suitable beam diagnostics.

Characterization of stress corrosion cracks in Ni-based weld alloys 52, 52M and 152 grown in high-temperature water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Yi; Wu, Yaqiao; Burns, Jatuporn

Ni-based weld alloys 52, 52M and 152 are extensively used in repair and mitigation of primary water stress corrosion cracking (SCC) in nuclear power plants. In the present study, a series of microstructure and microchemistry at the SCC tips of these alloys were examined with scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (STEM) and energy filtered transmission electron microscopy (EFTEM). The specimens have similar chemical compositions and testing conditions. Intergranular (IG) and transgranular (TG) SCC was observed in all of them. The cracks were filled with nickel-oxidesmore » and partial precipitations of chrome carbides (CrCs), niobium carbides (NbCs), titanium nitrides (TiNs) and silicon carbides (SiCs), while iron (Fe) was largely dissolved into the solution. However, the crack densities, lengths and distributions were different for all three specimens. - Highlights: • Microstructure and microchemistry at the SCC tips of Ni-based weld alloys 52, 52M and 152 were examined. • The crack densities, lengths and distributions were found to be different for different alloys. • IGSCC and TGSCC were observed on alloy 52, only TGSCC was observed on alloy 52M and 152. • The cracks were filled by Ni-oxides and precipitated CrCs, NbCs, TiNs and SiCs.« less

Fabrication and Characterization of CZTS Thin Films Prepared by the Sulfurization of RF-Sputtered Stacked Metal Precursors

NASA Astrophysics Data System (ADS)

Abusnina, Mohamed; Moutinho, Helio; Al-Jassim, Mowafak; DeHart, Clay; Matin, Mohammed

2014-09-01

In this work, Cu2ZnSnS4 (CZTS) thin films were prepared by the sulfurization of metal precursors deposited sequentially via radio frequency magnetron sputtering on Mo-coated soda-lime glass. The stack order of the precursors was Mo/Zn/Sn/Cu. Sputtered precursors were annealed in sulfur atmosphere with nine different conditions to study the impact of sulfurization time and substrate temperature on the structural, morphological, and optical properties of the final CZTS films. X-ray fluorescence was used to determine the elemental composition ratio of the metal precursors. Final CZTS films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). XRD and EDS were combined to investigate the films' structure and to identify the presence of secondary phases. XRD analysis indicated an improvement in film crystallinity with an increase of the substrate temperature and annealing times. Also indicated was the minimization and/or elimination of secondary phases when the films experienced longer annealing time. EDS revealed slight Sn loss in films sulfurized at 550°C; however, an increase of the sulfurization temperature to 600°C did not confirm these results. SEM study showed that films treated with higher temperatures exhibited dense morphology, indicating the completion of the sulfurization process. The estimated absorption coefficient was on the order of 104 cm-1 for all CZTS films, and the values obtained for the optical bandgap energy of the films were between 1.33 eV and 1.52 eV.

A comprehensive study on electrochemical performance of Mn-surface-modified LiNi0.8Co0.15Al0.05O2 synthesized by an in situ oxidizing-coating method

NASA Astrophysics Data System (ADS)

Huang, Bin; Li, Xinhai; Wang, Zhixing; Guo, Huajun; Shen, Li; Wang, Jiexi

2014-04-01

The degradation of Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material is successfully suppressed via a facile in situ oxidizing-coating method. KMnO4 is used as not only a Mn source but also an oxidant. X-ray diffraction (XRD) and scanning electron microscope (SEM) results demonstrate that the structure and morphology of the KMnO4-pretreated sample are the same as the pristine one. X-ray photoelectron spectroscopy (XPS) confirms that the valence state of Mn is +4 and the Ni3+ ions are partly reduced to Ni2+ when the material is doped with Mn4+. Besides, the Mn4+ ions are proved to distribute uniformly on the surface of the materials particles through energy dispersive spectrometer (EDS) and EDS elemental mapping. And it is confirmed that the concentration of Ni in the outer layer is reduced by the Mn-surface-modification. From the electrochemical characterizations, it is confirmed that the presence of tetravalent Mn at the surface can suppress the capacity fading during charge-discharge cycles, even under elevated temperature and overcharge conditions, and can prevent the material from deterioration during storage in air.

Green engineering of biomolecule-coated metallic silver nanoparticles and their potential cytotoxic activity against cancer cell lines

NASA Astrophysics Data System (ADS)

Prasannaraj, Govindaraj; Venkatachalam, Perumal

2017-06-01

This report describes the synthesis of metallic silver nanoparticles (AgNPs) using extracts of four medicinal plants (Aegle marmelos (A. marmelos), Alstonia scholaris (A. scholaris), Andrographis paniculata (A. paniculata) and Centella asiatica (C. asiatica)). The bio-conjugates were characterized by UV-visible spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectrometry (FTIR), x-ray diffraction (XRD) and zeta potential. This analysis confirmed that UV-Vis spectral peaks at 375 nm, 380 nm, 420 nm and 380 nm are corresponding to A. marmelos, A. scholaris, A. paniculata and C. asiatica mediated AgNPs, respectively. SEM images revealed that all the obtained four AgNPs are predominantly spherical, fibres and rectangle in shape with an average size of 36-97 nm. SEM-EDS and XRD analysis confirmed the presence of elemental AgNPs in crystalline form for all the four nanoparticle samples. The phytochemicals of various medicinal plant extracts with different functional groups were responsible for reduction of Ag+ to AgNPs, which act as capping and stabilizing agent. Among four types of AgNPs tested for anticancer activity, the Ap mediated AgNPs had shown enhanced activity against HepG2 cells (27.01 µg ml-1) and PC3 cells (32.15 µg ml-1).

Effects of crystallization and dopant concentration on the emission behavior of TiO2:Eu nanophosphors

PubMed Central

2012-01-01

Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing at 500°C for 2 h, the amorphous, as-grown nanoparticles could be converted to a pure anatase phase. The morphology, structural, and optical properties of the annealed nanostructures were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy [EDS], and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence [PL] spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration, crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu+3 ions, the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions. PMID:22214494

Synthesis of gadolinium carbonate-conjugated-poly(ethylene)glycol (Gd{sub 2}(CO{sub 3}){sub 3}@PEG) particles via a modified solvothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasution, Erika L. Y.; Ahab, Atika; Nuryadin, Bebeh W.

2016-02-08

PEGylated gadolinium carbonate ((Gd{sub 2}(CO{sub 3}){sub 3})@PEG) powder was successfully synthesized by a modified solvothermal method. The synthesized products were characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). A systematic change in the chemical surface composition, crystallinity and size properties of the Gd{sub 2}(CO{sub 3}){sub 3}@PEG particles was observed by increasing the reaction time at 5 hours, 7 hours, and 8 hours. The corresponding XRD patterns showed that the Gd{sub 2}(CO{sub 3}){sub 3} particles had hexagonal symmetry (JCPDS No. 37-0559) with a crystallite size of 3.5,more » 2.9, and 4.6 nm. FTIR spectra showed that the Gd{sub 2}(CO{sub 3}){sub 3})@PEG particles were formed with the PEG as carbonyl and hydroxyl group attached to the surface. SEM analysis showed that the Gd{sub 2}(CO{sub 3}){sub 3})@PEG particles had a flake-like morphology of homogeneous sized particles and agglomerates. EDS analysis confirmed the presence of constituent Gd{sub 2}(CO{sub 3}){sub 3} elements.« less

Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

NASA Astrophysics Data System (ADS)

Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

2017-07-01

A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

Structural and photocatalytic studies of hydrothermally synthesized Mn2+-TiO2 nanoparticles under UV and visible light irradiation

NASA Astrophysics Data System (ADS)

Kamble, Ravi; Sabale, Sandip; Chikode, Prashant; Puri, Vijaya; Mahajan, Smita

2016-11-01

Pure TiO2 and Mn2+-TiO2 nanoparticles have been prepared by simple hydrothermal method with different Mn2+ concentrations. Obtained samples were analysed to determine it’s structural, optical, morphological and compositional properties using x-ray diffraction, UV-DRS, Raman, photoluminescence, XPS, TEM and EDS analysis. The EDS micrograph confirms the existence of Mn2+ atoms in TiO2 matrix with 0.86, 1.60 and 1.90 wt%. The crystallite size as well as band gap decreases with increase in Mn2+ concentration. The average particle size obtained from TEM was found 8-11 nm which is in good agreement with XRD results. Raman bands at 640, 518 and 398 cm-1 further confirmed pure phase anatase in all samples. XPS shows the proper substitutions of few sites of Ti4+ ions by Mn2+ ions in the TiO2 host lattice. The intensity of PL spectra for Mn2+-TiO2 shows a gradual decrease in the peak intensity with increasing Mn2+ concentration in TiO2, it implies lower electron-hole recombination rate as Mn2+ ions increases. The obtained samples were further studied for its photocatalytic activities using malachite green dye under UV light and visible light.

Raman, SEM-EDS and XRPD investigations on pre-Columbian Central America "estucado" pottery

NASA Astrophysics Data System (ADS)

Casanova Municchia, Annalaura; Micheli, Mario; Ricci, Maria Antonietta; Toledo, Michelle; Bellatreccia, Fabio; Lo Mastro, Sergio; Sodo, Armida

2016-03-01

Seventeen different colored fragments from six selected pre-Columbian estucado ceramics from El Salvador have been investigated by Raman spectroscopy, scanning electron microscope coupled to an energy dispersive spectrometer (SEM/EDS) and X-ray powder diffraction (XRPD). The peculiarity of this kind of ceramics consist of the unusual presence of a white engobe, traditionally termed stucco, between the ceramic body and the decoration elements, hence the name estucado ceramics. The aim of this work was to study the unusual manufacturing technique and to identify the chemical composition of the engobe and of the pigment palette. The results showed that the stucco layer is made of clay (kaolinite) with traces of titanium oxide (anatase). Remarkably, this is the same composition of the white pigments used for the decoration layer, thus excluding an early use of natural titanium oxide as a white pigment in the estucado productions as suggested in previous investigations. Moreover, the presence of kaolinite and anatase both in the stucco and in the decoration layer suggests a cold-working or low temperature technique. The red, yellow and green decorations were realized by the use of natural ochre, while in all the blue and gray decorations Maya blue pigment was identified. Finally, an amorphous carbon pigment of vegetal origin and manganese oxide were used to obtain black pigments.

Nanomodulated electron beams via electron diffraction and emittance exchange for coherent x-ray generation

NASA Astrophysics Data System (ADS)

Nanni, E. A.; Graves, W. S.; Moncton, D. E.

2018-01-01

We present a new method for generation of relativistic electron beams with current modulation on the nanometer scale and below. The current modulation is produced by diffracting relativistic electrons in single crystal Si, accelerating the diffracted beam and imaging the crystal structure, then transferring the image into the temporal dimension via emittance exchange. The modulation period can be tuned by adjusting electron optics after diffraction. This tunable longitudinal modulation can have a period as short as a few angstroms, enabling production of coherent hard x-rays from a source based on inverse Compton scattering with total accelerator length of approximately ten meters. Electron beam simulations from cathode emission through diffraction, acceleration, and image formation with variable magnification are presented along with estimates of the coherent x-ray output properties.

Design of PdAg Hollow Nanoflowers through Galvanic Replacement and Their Application for Ethanol Electrooxidation.

PubMed

Bin, Duan; Yang, Beibei; Zhang, Ke; Wang, Caiqin; Wang, Jin; Zhong, Jiatai; Feng, Yue; Guo, Jun; Du, Yukou

2016-11-07

In this study, galvanic replacement provides a simple route for the synthesis of PdAg hollow nanoflower structures by using the Ag-seeds as sacrificial templates in the presence of l-ascorbic acid (reductant) and CTAC (capping agent). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and EDS mapping were used to characterize the as-prepared PdAg hollow nanoflower catalysts, where they were alloyed nanoflower structures with hollow interiors. By maneuvering the Pd/Ag ratio, we found that the as-prepared Pd 1 Ag 3 hollow nanoflower catalysts had the optimized performance for catalytic activity toward ethanol oxidation reaction. Moreover, these as-prepared PdAg hollow nanoflower catalysts exhibited noticeably higher electrocatalytic activity as compared to pure Pd and commercial Pd/C catalysts due to the alloyed Ag-Pd composition as well as the hollow nanoflower structures. It is anticipated that this work provides a rational design of other architecturally controlled bimetallic nanocrystals for application in fuel cells. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optoelectronic and Electrochemical Properties of Vanadium Pentoxide Nanowires Synthesized by Vapor-Solid Process

PubMed Central

Pan, Ko-Ying; Wei, Da-Hua

2016-01-01

Substantial synthetic vanadium pentoxide (V2O5) nanowires were successfully produced by a vapor-solid (VS) method of thermal evaporation without using precursors as nucleation sites for single crystalline V2O5 nanowires with a (110) growth plane. The micromorphology and microstructure of V2O5 nanowires were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). The spiral growth mechanism of V2O5 nanowires in the VS process is proved by a TEM image. The photo-luminescence (PL) spectrum of V2O5 nanowires shows intrinsic (410 nm and 560 nm) and defect-related (710 nm) emissions, which are ascribable to the bound of inter-band transitions (V 3d conduction band to O 2p valence band). The electrical resistivity could be evaluated as 64.62 Ω·cm via four-point probe method. The potential differences between oxidation peak and reduction peak are 0.861 V and 0.470 V for the first and 10th cycle, respectively. PMID:28335268

Simple solution-combustion synthesis of Ni-NiO@C nanocomposites with highly electrocatalytic activity for methanol oxidation

NASA Astrophysics Data System (ADS)

Yu, Jie; Ni, Yonghong; Zhai, Muheng

2018-01-01

Transition metal and its oxide composite nanomaterials are attracting increasing research interest due to their superior properties and extensive applications in many fields. In this paper, Ni-NiO@C nanocomposites were successfully synthesized in one step via a simple solution-combustion route, employing NiCl2 as the Ni source, oxygen in the atmosphere as the oxygen source, and ethanol as the solvent. The final product was characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), (high resolution) transmission electron microscopy (TEM/HRTEM), and Raman spectra. N2 gas sorption-desorption experiments uncovered that the BET surface area of Ni-NiO@C nanocomposites reached 161.9 m2 g-1, far higher than 34.2 m2 g-1 of Ni-NiO. The electrochemical measurement showed that the as-produced Ni-NiO@C nanocomposites presented better catalytic activity for the electro-oxidation of methanol than Ni-NiO and NiO, which provides a new catalyst selection for the electro-oxidation of methanol.

SAPO-34/AlMCM-41, as a novel hierarchical nanocomposite: preparation, characterization and investigation of synthesis factors using response surface methodology

NASA Astrophysics Data System (ADS)

Roohollahi, Hossein; Halladj, Rouein; Askari, Sima; Yaripour, Fereydoon

2018-06-01

SAPO-34/AlMCM-41, as a new hierarchical nanocomposite was successfully synthesized via hydrothermal and dry-gel conversion. In an experimental and statistical study, effect of five input parameters including synthesis period, drying temperature, NaOH/Si, water/dried-gel and SAPO% were investigated on range-order degree of mesochannels and the relative crystallinity. X-ray diffraction (XRD) patterns were recorded to characterize the ordered AlMCM-41 and crystalline SAPO-34 structures. Nitrogen adsorption-desorption technique, scanning electron microscopy (SEM), field-emission SEM (FESEM) equipped with an energy-dispersive X-ray spectroscopy (EDS-Map) and transmission electron microscopy (TEM) were used to study the textural properties, morphology and surface elemental composition. Two reduced polynomials were fitted to the responses with good precision. Further, based on analysis of variances, SAPO% and time duration of dry-gel conversion were observed as the most effective parameters on the composite structure. The hierarchical porosity, narrow pore size distribution, high external surface area and large specific pore volume were of interesting characteristics for this novel nanocomposite.

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

NASA Astrophysics Data System (ADS)

Xing, Weinan; Ni, Liang; Huo, Pengwei; Lu, Ziyang; Liu, Xinlin; Luo, Yingying; Yan, Yongsheng

2012-10-01

A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

Facile one-pot synthesis of hexagons of NaSrB5O9:Tb3+ phosphor for solid-state lighting

NASA Astrophysics Data System (ADS)

Ramesh, B.; Dillip, G. R.; Deva Prasad Raju, B.; Somasundaram, K.; Prasad Peddi, Siva; de Carvalho dos Anjos, Virgilio; Joo, S. W.

2017-04-01

NaSrB5O9:Tb3+ hexagons were synthesized by a facile solid-state reaction method. The synthesized powders were structurally examined by x-ray diffraction analysis (XRD), and Rietveld refinement was performed using the XRD data and Fullprof software. Hexagon-like morphology was observed using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The elemental composition of the phosphors was investigated qualitatively by energy dispersive x-ray analysis (EDS) and quantitatively by x-ray photoelectron spectroscopy (XPS). The phosphor has a strong green emission at 545 nm under excitation of 379 nm, which is due to the 5{{\\text{D}}4}{{\\to}7}{{\\text{F}}5} transition of the Tb3+ ion. A lifetime of 3.48 ms was obtained for the phosphor. The important parameters of the light source were determined, such as the thermal quenching, critical distance, the nature of the dopant ion interaction, color coordinates, and quantum yield values. Other reported properties include the site occupancy of the dopant, surface properties, morphological properties, and optical properties.

Contribution of Microchemical Surface Analysis of Archaeological Artefacts

NASA Astrophysics Data System (ADS)

Mousser, H.; Madani, A.; Amri, R.; Mousser, A.; Darchen, A.

2009-11-01

Museum CIRTA of the town of Constantine has a collection of more than 35000 coins and statuettes going back to Numide, Roman, Republican, Vandal and Byzantine times and is struck in the name of the cities, of the kingdoms and the empires. Surface analysis of these coins gives information about the chemical composition and leads to recommendations for restoration and preservations. This work is a contribution of microchemical surface study of coin with the effigy of the Numide King Massinissa (Constantine between 3rd and 2nd century before Jesus Christ). The photographic and scanning electron microscopy coupled with energy dispersive spectrometry (SEM + EDS) and diffraction of X-ray (DRX) was used. The optic microscopy (OMP) and SEM pictures of coins showed heterogeneous surface. Scanning electron microscopy coupled with energy dispersive spectrometry identified three basic metals copper (46.06%), antimony (17.74%) and lead (12.06%), (Weight Percentage). The DRX identifies stages (copper and lead) and their crystalline oxides Bindheimite (Pb2Sb2O7) and Bystromite (MgSb2O6) on the coin's surface.

Bricks in historical buildings of Toledo City: characterisation and restoration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez-Arce, Paula; Garcia-Guinea, Javier; Gracia, Mercedes

2003-01-15

Two different types of ancient bricks (12th to 14th centuries) collected from historical buildings of Toledo (Spain) were characterised by optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectrometers (SEM/EDS), electron probe microanalysis (EM), X-ray diffraction (XRD), differential thermal analysis (DTA) and {sup 57}Fe-Moessbauer spectroscopy. Physical properties such as water absorption and suction, porosity, density and compression strength were also determined. Several minerals found in the brick matrix, such as garnet, let us infer raw material sources; calcite, dolomite, illite and neoformed gehlenite and diopside phases, on temperature reached in firing; secondary calcite, on first cooling scenarios; and manganese micronodules, on latemore » pollution environments. XRD and DTA of original and refired samples supply information about firing temperatures. Additional data on firing conditions and type of the original clay are provided by the Moessbauer study. Physical properties of both types of bricks were compared and correlated with raw materials and fabric and firing technology employed. The physicochemical characterisation of these bricks provides valuable data for restoration purposes to formulate new specific bricks using neighbouring raw materials.« less

Electrodeposition of Ni and CeO₂/Ni Nanotubes for Hydrogen Evolution Reaction Electrode.

PubMed

Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

2018-07-01

Ni NTs and CeO2-Ni nanotubes (NTs) have been prepared by galvanostatic electrodeposition in anodic aluminum oxide (AAO) Templates. Scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopic (EDS) and X-ray Diffraction (XRD) are used to characterize the prepared NTs. The results showed that the preparation process of CeO2-Ni NTs was accompanied by the formation of many new phases CeNix (x = 1, 2, 3.5 or 5) and preferential orientation crystal face of Ni in CeO2-Ni NTs is 〈111〉, which is different from that Ni 〈200〉 in Ni NTs. Then linear scan voltammetry (LSV) is applied to test the electrocatalytic activity for hydrogen revolution reaction (HER) of the two electrodes in 1 M NaCl aqueous solution and find that both of the two materials exhibited good performance. Finally, the kinetics analyses from the HER process showed that Tafel slope b was mainly dependent on phase composition and electric conductivity of the electrode, while j0 was mainly dependent on its real specific surface area.

Photo-induced self-cleaning and sterilizing activity of Sm3+ doped ZnO nanomaterials.

PubMed

Saif, M; Hafez, H; Nabeel, A I

2013-01-01

Highly active samarium doped zinc oxide self-cleaning and biocidal surfaces (x mol% Sm(3+)/ZnO where x=0, 1, 2 and 4 mol%) with crystalline porous structures were synthesized by hydrothermal method. Sm(3+)/ZnO thin films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopic (EDS), UV-visible diffuse reflectance and fluorescence (FL) spectroscopy. The combination between doping and hydrothermal treatments significantly altered the morphology of ZnO into rod and plate-like nanoshapes structure and enhanced its absorption and emission of ultraviolet radiation. The photo-activity in term of quantitative determination of the active oxidative species (()OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results showed that, the hydrothermally treated 2.0 mol% Sm(3+)/ZnO film (S2) is the highly active one. The optical, structural, morphology and photo-activity properties of the highly active thin film (S2) make it promising surface for self-cleaning and sterilizing applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Aluminium electrodeposition in chloroaluminate ionic liquid.

PubMed

Zhang, Lipeng; Wang, Enqi; Mu, Jiechen; Yu, Xianjin; Wang, Qiannan; Yang, Lina; Zhao, Zengdian

2014-08-01

An efficient microwave enhanced synthesis of ambient temperature chloroaluminate ionic liquid ([EMIM]Br) that preceeds reaction of 1-methylimidazolium with bromoethane in a closed vessel, was described in our work. The reaction time was drastically reduced as compared to the conventional methods. The electrochemical techniques of impedance spectroscopy, cyclic voltammetry and chronoamperometry were used to investigate the mechanism of Al electrodeposition from 2:1 (molar ratio) AlCl3/[EMIM]Br ionic liquid at room temperature. Results indicated that Al electrode- position from this ionic liqud was a quasi-reversible process, and the kinetic complications during the reaction was probably attributed to the electron transfer or mass transport cooperative controlled processes, instantaneous nucleation with diffusion-controlled growth was also investigated. Electrodepositon experiment was conducted using constant current density of 40 mA·cm(-2) for 20 minutes at room temperature and the qualitative analysis of the deposits were performed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and energy dispersive spectroscope (EDS). The deposits obtained on copper cathode were dense and compact and most Al crystal shows granular structure spherical with high purity.

Ex Situ Investigation of Anisotropic Interconnection in Silicon-Titanium-Nickel Alloy Anode Material

DOE PAGES

Cho, Jong -Soo; Alaboina, Pankaj Kumar; Kang, Chan -Soon; ...

2017-03-10

Herein we investigate the nanostructural evolution of Silicon-Titanium-Nickel (Si-Ti-Ni) ternary alloy material synthesized by melt spinning process for advanced lithium-ion battery anode. The synthesized material was found to have nano-Silicon particles dispersed in the Ti 4Ni 4Si 7 (STN) alloy buffering matrix and was characterized by X-ray diffraction (XRD), High resolution- transmission electron microscope (HR-TEM), Scanning transmission electron microscopes - energy dispersive X-ray spectrometer (STEM-EDS), and electrochemical performance test. The role of STN matrix is to accommodate the volume expansion stresses of the dispersed Si nanoparticles. However, an interesting behavior was observed during cycling. The Si nanoparticles were observed tomore » form interconnection channels growing through the weak STN matrix cracks and evolving to a network isolating the STN matrix into small puddles. In conclusion, this unique nanostructural evolution of Si particles and isolation of the STN matrix failing to offer significant buffering effect to the grown Si network eventually accelerates more volume expansions during cycling due to less mechanical confinement and leads to performance degradation and poor cycle stability.« less

Synthesis of Crooked Gold Nanocrystals by Electrochemical Technique

NASA Astrophysics Data System (ADS)

Huang, Chien-Jung; Chiu, Pin-Hsiang; Chen, Ming-Da; Meen, Teen-Hang

2005-07-01

In this article, we demonstrate the synthesis of crooked gold nanocrystals (CGNCs) by an electrochemical technique using micelle templates formed by two surfactants with different amounts of isopropanol solvent, the primary surfactant being hexadecyltrimethylammonium bromide (C16TABr) and the cosurfactant being tetradodecylammonium bromide (TC12ABr). To investigate the influence of isopropanol solvent on the CGNCs, the amount of isopropanol was varied in the range from 50 to 300 μL. It was found that the aspect ratios (γ) of CGNCs were in the range from 1.06 to 1.46, and the UV--vis optical absorption measurement revealed a pronounced redshift of the surface plasmon band from 532 to 560 nm. The CGNCs were composed of many large gold grains with small gold nuclei, and it was determined that several grains are present within each of the CGNCs using a dark-field transmission electron microscopy (TEM) image. It is suggested that the CGNCs have a polycrystalline structure. The CGNCs have been determined to be pure gold with a face-centered cubic (fcc) structure by electron diffraction (ED) analysis.

Synthesis of Fluorinated Graphene/CoAl-Layered Double Hydroxide Composites as Electrode Materials for Supercapacitors.

PubMed

Peng, Weijun; Li, Hongqiang; Song, Shaoxian

2017-02-15

CoAl-layered double hydroxide/fluorinated graphene (CoAl-LDH/FGN) composites were fabricated via a two-step hydrothermal method. The synthesized CoAl-LDH/FGN composites have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and electrochemical measurements. The results indicated that the fluorinated carbon with various configuration forms were grafted onto the framework of graphene, and the C-F bond configuration and fluorine content could be tuned by the fluorination time. Most of semi-ionic C-F bonds were formed at an appropriate fluorination time and, then, converted into fluorine rich surface groups (such as CF 2 , CF 3 , etc.) which were electrochemically inactive as the fluorination time prolonged. Moreover, the CoAl-LDH/FGN composites prepared at the optimal fluorination time exhibited the highest specific capacitance (1222 F/g at 1 A/g), the best rate capability, and the most stable capacitance retention, which offered great promise as electrode materials for supercapacitors.

Improving the catalytic activity of magnetic Fe3O4/ZnO-CdO/reduced graphene oxide for ultrasonic degradation of the organic pollutants and the green oxidation of olefins

NASA Astrophysics Data System (ADS)

Mirzazadeh, Hoda; Lashanizadegan, Maryam

2018-05-01

Magnetic Fe3O4/ZnO-CdO/reduced graphene oxide (MFZC/RGO) has been synthesized by simple hydrothermal method. The structure and morphology were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), Vibrating sample magnetometer (VSM), Raman and Fourier-transform infrared spectroscopy (FTIR). MFZC/RGO was applied as catalyst in degradation of methylene blue (MB), rhodamin B (RhB) and methylorange (MO) under ultrasonic irradiation. Based on the results, excellent degradation efficiencies of MB, RhB and MO (>99%) were achieved within 10, 20 and 20 min, respectively under oxygen flow. Moreover the catalytic property of MFZC/RGO was investigated in oxidation of styrene, α-methyl styrene, cyclohexene and cyclooctene under oxygen flow. In addition, MFZC/RGO can be easily collected and separated by an external magnet. The catalyst displayed negligible loss in activity and selectivity within several successive runs due to super paramagnetism.

Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

NASA Astrophysics Data System (ADS)

Lyu, Jianchang; Li, Zhenlu; Ge, Ming

2018-06-01

Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO3. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O2•-) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.

Energy-weighted dynamical scattering simulations of electron diffraction modalities in the scanning electron microscope.

PubMed

Pascal, Elena; Singh, Saransh; Callahan, Patrick G; Hourahine, Ben; Trager-Cowan, Carol; Graef, Marc De

2018-04-01

Transmission Kikuchi diffraction (TKD) has been gaining momentum as a high resolution alternative to electron back-scattered diffraction (EBSD), adding to the existing electron diffraction modalities in the scanning electron microscope (SEM). The image simulation of any of these measurement techniques requires an energy dependent diffraction model for which, in turn, knowledge of electron energies and diffraction distances distributions is required. We identify the sample-detector geometry and the effect of inelastic events on the diffracting electron beam as the important factors to be considered when predicting these distributions. However, tractable models taking into account inelastic scattering explicitly are lacking. In this study, we expand the Monte Carlo (MC) energy-weighting dynamical simulations models used for EBSD [1] and ECP [2] to the TKD case. We show that the foil thickness in TKD can be used as a means of energy filtering and compare band sharpness in the different modalities. The current model is shown to correctly predict TKD patterns and, through the dictionary indexing approach, to produce higher quality indexed TKD maps than conventional Hough transform approach, especially close to grain boundaries. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Femtosecond time-resolved MeV electron diffraction

DOE PAGES

Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; ...

2015-06-02

We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS 2 are obtained utilizing a 5 fC (~3 × 10 4 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated bymore » observing the evolution of Bragg and superlattice peaks of 1T-TaS 2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.« less

Electron diffraction covering a wide angular range from Bragg diffraction to small-angle diffraction.

PubMed

Nakajima, Hiroshi; Kotani, Atsuhiro; Harada, Ken; Mori, Shigeo

2018-04-09

We construct an electron optical system to investigate Bragg diffraction (the crystal lattice plane, 10-2 to 10-3 rad) with the objective lens turned off by adjusting the current in the intermediate lenses. A crossover was located on the selected-area aperture plane. Thus, the dark-field imaging can be performed by using a selected-area aperture to select Bragg diffraction spots. The camera length can be controlled in the range of 0.8-4 m without exciting the objective lens. Furthermore, we can observe the magnetic-field dependence of electron diffraction using the objective lens under weak excitation conditions. The diffraction mode for Bragg diffraction can be easily switched to a small-angle electron diffraction mode having a camera length of more than 100 m. We propose this experimental method to acquire electron diffraction patterns that depict an extensive angular range from 10-2 to 10-7 rad. This method is applied to analyze the magnetic microstructures in three distinct magnetic materials, i.e. a uniaxial magnetic structure of BaFe10.35Sc1.6Mg0.05O19, a martensite of a Ni-Mn-Ga alloy, and a helical magnetic structure of Ba0.5Sr1.5Zn2Fe12O22.

Hybrid Modes in Long Wavelength Free Electron Lasers

DTIC Science & Technology

2010-12-01

response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and...diffraction along one axis, allowing free space diffraction along the other axis. We continue the analysis of the relativistic electron beam, co-propagating...control diffraction along one axis, allowing free space diffraction along the other axis. We continue the analysis of the relativistic electron beam, co

Structure analysis of the single-domain Si(111)4 × 1-In surface by μ-probe Auger electron diffraction and μ-probe reflection high energy electron diffraction

NASA Astrophysics Data System (ADS)

Nakamura, N.; Anno, K.; Kono, S.

1991-10-01

A single-domain Si(111)4 × 1-In surface has been studied by μ-probe reflection high-energy electron diffraction (RHEED) to elucidate the symmetry of the 4 × 1 surface. Azimuthal diffraction patterns of In MNN Auger electron have been obtained by a μ-probe Auger electron diffraction (AED) apparatus from the single-domain Si(111)4 × 1-In surface. On the basis of information from scanning tunneling microscopy [J. Microsc. 152 (1988) 727] and under the assumption that the 4 × 1 surface is composed of In-overlayers, the μ-probe AED patterns were kinematically analyzed to reach a concrete model of indium arrangement.

Is scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) quantitative?

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2013-01-01

Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) is a widely applied elemental microanalysis method capable of identifying and quantifying all elements in the periodic table except H, He, and Li. By following the "k-ratio" (unknown/standard) measurement protocol development for electron-excited wavelength dispersive spectrometry (WDS), SEM/EDS can achieve accuracy and precision equivalent to WDS and at substantially lower electron dose, even when severe X-ray peak overlaps occur, provided sufficient counts are recorded. Achieving this level of performance is now much more practical with the advent of the high-throughput silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS). However, three measurement issues continue to diminish the impact of SEM/EDS: (1) In the qualitative analysis (i.e., element identification) that must precede quantitative analysis, at least some current and many legacy software systems are vulnerable to occasional misidentification of major constituent peaks, with the frequency of misidentifications rising significantly for minor and trace constituents. (2) The use of standardless analysis, which is subject to much broader systematic errors, leads to quantitative results that, while useful, do not have sufficient accuracy to solve critical problems, e.g. determining the formula of a compound. (3) EDS spectrometers have such a large volume of acceptance that apparently credible spectra can be obtained from specimens with complex topography that introduce uncontrolled geometric factors that modify X-ray generation and propagation, resulting in very large systematic errors, often a factor of ten or more. © Wiley Periodicals, Inc.

Improving Recognition of Pediatric Severe Sepsis in the Emergency Department: Contributions of a Vital Sign-Based Electronic Alert and Bedside Clinician Identification.

PubMed

Balamuth, Fran; Alpern, Elizabeth R; Abbadessa, Mary Kate; Hayes, Katie; Schast, Aileen; Lavelle, Jane; Fitzgerald, Julie C; Weiss, Scott L; Zorc, Joseph J

2017-12-01

Recognition of pediatric sepsis is a key clinical challenge. We evaluate the performance of a sepsis recognition process including an electronic sepsis alert and bedside assessment in a pediatric emergency department (ED). This was a cohort study with quality improvement intervention in a pediatric ED. Exposure was a positive electronic sepsis alert, defined as elevated pulse rate or hypotension, concern for infection, and at least one of the following: abnormal capillary refill, abnormal mental status, or high-risk condition. A positive electronic sepsis alert prompted team assessment or huddle to determine need for sepsis protocol. Clinicians could initiate team assessment or huddle according to clinical concern without positive electronic sepsis alert. Severe sepsis outcome defined as activation of the sepsis protocol in the ED or development of severe sepsis requiring ICU admission within 24 hours. There were 182,509 ED visits during the study period, with 86,037 before electronic sepsis alert implementation and 96,472 afterward, and 1,112 (1.2%) positive electronic sepsis alerts. Overall, 326 patients (0.3%) were treated for severe sepsis within 24 hours. Test characteristics of the electronic sepsis alert alone to detect severe sepsis were sensitivity 86.2% (95% confidence interval [CI] 82.0% to 89.5%), specificity 99.1% (95% CI 99.0% to 99.2%), positive predictive value 25.4% (95% CI 22.8% to 28.0%), and negative predictive value 100% (95% CI 99.9% to 100%). Inclusion of the clinician screen identified 43 additional electronic sepsis alert-negative children, with severe sepsis sensitivity 99.4% (95% CI 97.8% to 99.8%) and specificity 99.1% (95% CI 99.1% to 99.2%). Electronic sepsis alert implementation increased ED sepsis detection from 83% to 96%. Electronic sepsis alert for severe sepsis demonstrated good sensitivity and high specificity. Addition of clinician identification of electronic sepsis alert-negative patients further improved sensitivity. Implementation of the electronic sepsis alert was associated with improved recognition of severe sepsis. Copyright © 2017 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

Nanomodulated electron beams via electron diffraction and emittance exchange for coherent x-ray generation

DOE PAGES

Nanni, E. A.; Graves, W. S.; Moncton, D. E.

2018-01-19

We present a new method for generation of relativistic electron beams with current modulation on the nanometer scale and below. The current modulation is produced by diffracting relativistic electrons in single crystal Si, accelerating the diffracted beam and imaging the crystal structure, then transferring the image into the temporal dimension via emittance exchange. The modulation period can be tuned by adjusting electron optics after diffraction. This tunable longitudinal modulation can have a period as short as a few angstroms, enabling production of coherent hard x-rays from a source based on inverse Compton scattering with total accelerator length of approximately tenmore » meters. Electron beam simulations from cathode emission through diffraction, acceleration, and image formation with variable magnification are presented along with estimates of the coherent x-ray output properties.« less

Nanomodulated electron beams via electron diffraction and emittance exchange for coherent x-ray generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanni, E. A.; Graves, W. S.; Moncton, D. E.

We present a new method for generation of relativistic electron beams with current modulation on the nanometer scale and below. The current modulation is produced by diffracting relativistic electrons in single crystal Si, accelerating the diffracted beam and imaging the crystal structure, then transferring the image into the temporal dimension via emittance exchange. The modulation period can be tuned by adjusting electron optics after diffraction. This tunable longitudinal modulation can have a period as short as a few angstroms, enabling production of coherent hard x-rays from a source based on inverse Compton scattering with total accelerator length of approximately tenmore » meters. Electron beam simulations from cathode emission through diffraction, acceleration, and image formation with variable magnification are presented along with estimates of the coherent x-ray output properties.« less

Decagonal quasicrystal and related crystalline phases in Mn-Ga alloys with 52 to 63 a/o Ga

NASA Astrophysics Data System (ADS)

Wu, J. S.; Kuo, K. H.

1997-03-01

A decagonal quasicrystal (DQC) and six related intermetallic phases with large unit cells have been found in binary Mn-Ga alloys with 52 to 63 at. pct Ga by means of transmission electron microscopy (TEM). As does the Al-Mn DQC, the Ga-Mn DQC also has a periodicity of 1.25 nm along its tenfold axis. However, its Mn content, determined by electron microprobe X-ray analysis (about 45 to 50 at. pct Mn), is much higher than that of the Al-Mn DQC (about 20 to 30 at. pct Mn). The compositions of the intermetallic phases are about 53, 56, 58, and 62 at. pct Ga, corresponding respectively to the unknown structures of MnGa (50.7 to 53.4 at. pct Ga), Mn5Ga6 (55 at pct Ga), Mn5Ga7 (57.9 at. pct Ga), and Mn3Ga5 (62.9 at. pct Ga) given in the binary Mn-Ga phase diagram ( Metals Hand-book, T.B. Massalski, J.L. Murray, L.H. Benneft, and H. Baker, eds., ASM, Metals Park, OH, 1986, vol. 2, p. 1144). Their lattice types have been determined by selected area electron diffraction. The ferromagnetic Mn3Ga5 is tetragonal, a=1.25 nm and c=2.50 nm; Mn5Ga7 is orthorhombic, a=4.57 nm, b=1.25 nm, and c=1.44 nm; Mn5Ga6 has two different but closely related orthorhombic unit cells, a=1.26 nm, b=1.25 nm, and c=1.48 nm as well as a=0.77 nm, b=1.25 nm, and c=2.36 nm; MnGa also has two different and related unit cells, one orthorhombic with a=2.04 nm, b=1.25 nm, and c=1.48 nm and the other monoclinic with a=2.59 nm, b=1.25 nm, c=1.15 nm, and β≈=110 deg. All these orthorhombic phases have b=1.25 nm, being the same as the periodicity along the tenfold axis of the Ga-Mn and Al-Mn DQCs. Moreover, all these six intermetallic phases give electron diffraction patterns displaying a pseudo-tenfold distribution of strong diffraction spots and are considered to be crystalline approximants of the Ga-Mn DQC.

High-efficiency thermoelectric Ba8Cu14Ge6P26: bridging the gap between tetrel-based and tetrel-free clathrates† †Electronic supplementary information (ESI) available: Calculated and experimental powder XRD patterns; tables with crystallographic information; SEM and EDS results; additional DSC, thermal conductivities, and ZT figures. CCDC 1568106. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03482b

PubMed Central

Wang, Jian; Lebedev, Oleg I.; Lee, Kathleen; Dolyniuk, Juli-Anna; Klavins, Peter; Bux, Sabah

2017-01-01

A new type-I clathrate, Ba8Cu14Ge6P26, was synthesized by solid-state methods as a polycrystalline powder and grown as a cm-sized single crystal via the vertical Bridgman method. Single-crystal and powder X-ray diffraction show that Ba8Cu14Ge6P26 crystallizes in the cubic space group Pm3n (no. 223). Ba8Cu14Ge6P26 is the first representative of anionic clathrates whose framework is composed of three atom types of very different chemical natures: a transition metal, tetrel element, and pnicogen. Uniform distribution of the Cu, Ge, and P atoms over the framework sites and the absence of any superstructural or local ordering in Ba8Cu14Ge6P26 were confirmed by synchrotron X-ray diffraction, electron diffraction and high-angle annular dark field scanning transmission electron microscopy, and neutron and X-ray pair distribution function analyses. Characterization of the transport properties demonstrate that Ba8Cu14Ge6P26 is a p-type semiconductor with an intrinsically low thermal conductivity of 0.72 W m–1 K–1 at 812 K. The thermoelectric figure of merit, ZT, for a slice of the Bridgman-grown crystal of Ba8Cu14Ge6P26 approaches 0.63 at 812 K due to a high power factor of 5.62 μW cm–1 K–2. The thermoelectric efficiency of Ba8Cu14Ge6P26 is on par with the best optimized p-type Ge-based clathrates and outperforms the majority of clathrates in the 700–850 K temperature region, including all tetrel-free clathrates. Ba8Cu14Ge6P26 expands clathrate chemistry by bridging conventional tetrel-based and tetrel-free clathrates. Advanced transport properties, in combination with earth-abundant framework elements and congruent melting make Ba8Cu14Ge6P26 a strong candidate as a novel and efficient thermoelectric material. PMID:29568451

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Haishuang; Krysiak, Yaşar; Hoffmann, Kristin

The crystal structure and disorder phenomena of Al{sub 4}B{sub 2}O{sub 9}, an aluminum borate from the mullite-type family, were studied using automated diffraction tomography (ADT), a recently established method for collection and analysis of electron diffraction data. Al{sub 4}B{sub 2}O{sub 9}, prepared by sol-gel approach, crystallizes in the monoclinic space group C2/m. The ab initio structure determination based on three-dimensional electron diffraction data from single ordered crystals reveals that edge-connected AlO{sub 6} octahedra expanding along the b axis constitute the backbone. The ordered structure (A) was confirmed by TEM and HAADF-STEM images. Furthermore, disordered crystals with diffuse scattering along themore » b axis are observed. Analysis of the modulation pattern implies a mean superstructure (AAB) with a threefold b axis, where B corresponds to an A layer shifted by ½a and ½c. Diffraction patterns simulated for the AAB sequence including additional stacking disorder are in good agreement with experimental electron diffraction patterns. - Graphical abstract: Crystal structure and disorder phenomena of B-rich Al{sub 4}B{sub 2}O{sub 9} studied by automated electron diffraction tomography (ADT) and described by diffraction simulation using DISCUS. - Highlights: • Ab-initio structure solution by electron diffraction from single nanocrystals. • Detected modulation corresponding mainly to three-fold superstructure. • Diffuse diffraction streaks caused by stacking faults in disordered crystals. • Observed streaks explained by simulated electron diffraction patterns.« less

The effect of electronic health record implementation on community emergency department operational measures of performance.

PubMed

Ward, Michael J; Landman, Adam B; Case, Karen; Berthelot, Jessica; Pilgrim, Randy L; Pines, Jesse M

2014-06-01

We study the effect of an emergency department (ED) electronic health record implementation on the operational metrics of a diverse group of community EDs. We performed a retrospective before/after analysis of 23 EDs from a single management group that experienced ED electronic health record implementation (with the majority of electronic health records optimized specifically for ED use). We obtained electronic data for 4 length of stay measures (arrival to provider, admitted, discharged, and overall length of stay) and 4 measures of operational characteristics (left before treatment complete, significant returns, overall patient satisfaction, and provider efficiency). We compared the 6-month "baseline" period immediately before implementation with a "steady-state" period commencing 6 months after implementation for all 8 metrics. For the length of stay measures, there were no differences in the arrival-to-provider interval (difference of -0.02 hours; 95% confidence interval [CI] of difference -0.12 to 0.08), admitted length of stay (difference of 0.10 hours; 95% CI of difference -0.17 to 0.37), discharged length of stay (difference of 0.07 hours; 95% CI of difference -0.07 to 0.22), and overall length of stay (difference of 0.11 hours; 95% CI of difference -0.04 to 0.27). For operational characteristics, there were no differences in the percentage who left before treatment was complete (difference of 0.24%; 95% CI of difference -0.47% to 0.95%), significant returns (difference of -0.04%; 95% CI of difference -0.48% to 0.39%), overall percentile patient satisfaction (difference of -0.02%; 95% CI of difference -2.35% to 2.30%), and provider efficiency (difference of -0.05 patients/hour; 95% CI of difference -0.11 to 0.02). There is no meaningful difference in 8 measures of operational performance for community EDs experiencing optimized ED electronic health record implementation between a baseline and steady-state period. Copyright © 2014 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Physicochemical characterization of Capstone depleted uranium aerosols III: morphologic and chemical oxide analyses.

PubMed

Krupka, Kenneth M; Parkhurst, Mary Ann; Gold, Kenneth; Arey, Bruce W; Jenson, Evan D; Guilmette, Raymond A

2009-03-01

The impact of depleted uranium (DU) penetrators against an armored target causes erosion and fragmentation of the penetrators, the extent of which is dependent on the thickness and material composition of the target. Vigorous oxidation of the DU particles and fragments creates an aerosol of DU oxide particles and DU particle agglomerations combined with target materials. Aerosols from the Capstone DU aerosol study, in which vehicles were perforated by DU penetrators, were evaluated for their oxidation states using x-ray diffraction (XRD), and particle morphologies were examined using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The oxidation state of a DU aerosol is important as it offers a clue to its solubility in lung fluids. The XRD analysis showed that the aerosols evaluated were a combination primarily of U3O8 (insoluble) and UO3 (relatively more soluble) phases, though intermediate phases resembling U4O9 and other oxides were prominent in some samples. Analysis of particle residues in the micrometer-size range by SEM/EDS provided microstructural information such as phase composition and distribution, fracture morphology, size distribution, and material homogeneity. Observations from SEM analysis show a wide variability in the shapes of the DU particles. Some of the larger particles were spherical, occasionally with dendritic or lobed surface structures. Others appear to have fractures that perhaps resulted from abrasion and comminution, or shear bands that developed from plastic deformation of the DU material. Amorphous conglomerates containing metals other than uranium were also common, especially with the smallest particle sizes. A few samples seemed to contain small bits of nearly pure uranium metal, which were verified by EDS to have a higher uranium content exceeding that expected for uranium oxides. Results of the XRD and SEM/EDS analyses were used in other studies described in this issue of Health Physics to interpret the results of lung solubility studies and in selecting input parameters for dose assessments.

Physicochemical Characterization of Capstone Depleted Uranium Aerosols III: Morphologic and Chemical Oxide Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupka, Kenneth M.; Parkhurst, MaryAnn; Gold, Kenneth

2009-03-01

The impact of depleted uranium (DU) penetrators against an armored target causes erosion and fragmentation of the penetrators, the extent of which is dependent on the thickness and material composition of the target. Vigorous oxidation of the DU particles and fragments creates an aerosol of DU oxide particles and DU particle agglomerations combined with target materials. Aerosols from the Capstone DU aerosol study, in which vehicles were perforated by DU penetrators, were evaluated for their oxidation states using X-ray diffraction (XRD) and particle morphologies using scanning electron microscopy/energy dispersive spectrometry (SEM/EDS). The oxidation state of a DU aerosol is importantmore » as it offers a clue to its solubility in lung fluids. The XRD analysis showed that the aerosols evaluated were a combination primarily of U3O8 (insoluble) and UO3 (relatively more soluble) phases, though intermediate phases resembling U4O9 and other oxides were prominent in some samples. Analysis of particle residues in the micrometer-size range by SEM/EDS provided microstructural information such as phase composition and distribution, fracture morphology, size distribution, and material homogeneity. Observations from SEM analysis show a wide variability in the shapes of the DU particles. Some of the larger particles appear to have been fractured (perhaps as a result of abrasion and comminution); others were spherical, occasionally with dendritic or lobed surface structures. Amorphous conglomerates containing metals other than uranium were also common, especially with the smallest particle sizes. A few samples seemed to contain small chunks of nearly pure uranium metal, which were verified by EDS to have a higher uranium content exceeding that expected for uranium oxides. Results of the XRD and SEM/EDS analyses were used in other studies described in this issue of The Journal of Health Physics to interpret the results of lung solubility studies and in selecting input parameters for dose assessments.« less

Observations on the Role of Hydrogen in Facet Formation in Near-alpha Titanium (Preprint)

DTIC Science & Technology

2011-05-01

using quantitative tilt fractography and electron backscatter diffraction while facet topography was examined using ultra high resolution scanning...quantitative tilt fractography and electron backscatter diffraction while facet topography was examined using ultra high resolution scanning electron...tilt fractography / electron backscatter diffraction (EBSD) technique in which both the crystallographic orientation of the fractured grain and the

Elimination of Emergency Department Medication Errors Due To Estimated Weights.

PubMed

Greenwalt, Mary; Griffen, David; Wilkerson, Jim

2017-01-01

From 7/2014 through 6/2015, 10 emergency department (ED) medication dosing errors were reported through the electronic incident reporting system of an urban academic medical center. Analysis of these medication errors identified inaccurate estimated weight on patients as the root cause. The goal of this project was to reduce weight-based dosing medication errors due to inaccurate estimated weights on patients presenting to the ED. Chart review revealed that 13.8% of estimated weights documented on admitted ED patients varied more than 10% from subsequent actual admission weights recorded. A random sample of 100 charts containing estimated weights revealed 2 previously unreported significant medication dosage errors (.02 significant error rate). Key improvements included removing barriers to weighing ED patients, storytelling to engage staff and change culture, and removal of the estimated weight documentation field from the ED electronic health record (EHR) forms. With these improvements estimated weights on ED patients, and the resulting medication errors, were eliminated.

Comparing the detection of iron-based pottery pigment on a carbon-coated sherd by SEM-EDS and by Micro-XRF-SEM.

PubMed

Pendleton, Michael W; Washburn, Dorothy K; Ellis, E Ann; Pendleton, Bonnie B

2014-03-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Comparing the Detection of Iron-Based Pottery Pigment on a Carbon-Coated Sherd by SEM-EDS and by Micro-XRF-SEM

PubMed Central

Pendleton, Michael W.; Washburn, Dorothy K.; Ellis, E. Ann; Pendleton, Bonnie B.

2014-01-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis. PMID:24600333

Total-scattering pair-distribution function of organic material from powder electron diffraction data.

PubMed

Gorelik, Tatiana E; Schmidt, Martin U; Kolb, Ute; Billinge, Simon J L

2015-04-01

This paper shows that pair-distribution function (PDF) analyses can be carried out on organic and organometallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction and nanodiffraction in transmission electron microscopy or nanodiffraction in scanning transmission electron microscopy modes. The methods were demonstrated on organometallic complexes (chlorinated and unchlorinated copper phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering data and avoiding beam damage of the sample are possible to resolve.

Diffraction of dust acoustic waves by a circular cylinder

NASA Astrophysics Data System (ADS)

Kim, S.-H.; Heinrich, J. R.; Merlino, R. L.

2008-09-01

The diffraction of dust acoustic (DA) waves around a long dielectric rod is observed using video imaging methods. The DA waves are spontaneously excited in a dusty plasma produced in a direct current glow discharge plasma. The rod acquires a negative charge that produces a coaxial dust void around it. The diameter of the void is the effective size of the "obstacle" encountered by the waves. The wavelength of the DA waves is approximately the size of the void. The observations are considered in relation to the classical problem of the diffraction of sound waves from a circular cylinder, a problem first analyzed by Lord Rayleigh [Theory of Sound, 2nd ed. (MacMillan, London, 1896)].

rf streak camera based ultrafast relativistic electron diffraction.

PubMed

Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Tran, T

2009-01-01

We theoretically and experimentally investigate the possibility of using a rf streak camera to time resolve in a single shot structural changes at the sub-100 fs time scale via relativistic electron diffraction. We experimentally tested this novel concept at the UCLA Pegasus rf photoinjector. Time-resolved diffraction patterns from thin Al foil are recorded. Averaging over 50 shots is required in order to get statistics sufficient to uncover a variation in time of the diffraction patterns. In the absence of an external pump laser, this is explained as due to the energy chirp on the beam out of the electron gun. With further improvements to the electron source, rf streak camera based ultrafast electron diffraction has the potential to yield truly single shot measurements of ultrafast processes.

Hexagonal OsB 2: Sintering, microstructure and mechanical properties

DOE PAGES

Xie, Zhilin; Lugovy, Mykola; Orlovskaya, Nina; ...

2015-02-07

In this study, the metastable high pressure ReB 2-type hexagonal OsB 2 bulk ceramics was produced by spark plasma sintering. The phase composition, microstructure, and mechanical behavior of the sintered OsB 2 were studied by X-ray diffraction, optical microscopy, TEM, SEM, EDS, and nanoindentation. The produced ceramics was rather porous and contained a mixture of hexagonal (~80 wt.%) and orthorhombic (~20 wt.%) phases as identified by X-ray diffraction and EBSD analysis. Two boron-rich phases, which do not contain Os, were also identified by TEM and SEM/EDS analysis. Nanoindentation measurements yielded a hardness of 31 ± 9 GPa and Young’s modulusmore » of 574 ± 112 GPa, indicating that the material is rather hard and very stiff; but, it is very prone to crack formation and propagation, which is indicative of a very brittle nature of this material. Improvements in the sintering regime are required in order to produce dense, homogeneous and single phase hexagonal OsB 2 bulk ceramics.« less

Fabrication and Characterizations of Ethanol Sensor Based on CuO Nanoparticles.

PubMed

Al-Hadeethi, Yas; Umar, Ahmad; Kumar, Rajesh; Al-Heniti, Saleh H; Raffah, Bahaaudin M

2018-04-01

In this paper, we report the synthesis, characterization and ethanol sensing applications of CuO nanoparticles. The CuO nanoparticles were prepared by a facile, low-temperature hydrothermal method and characterized in detail in terms of their structural, morphological, compositional and crystalline properties, through different characterization techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The detailed studies revealed that the synthesized CuO nanoparticles were well-crystalline and possessed monoclinic crystal structure. The synthesized CuO nanoparticles were utilized for the fabrication of highly sensitive ethanol gas sensor. At an optimized temperature of 320 °C, high sensitivity (Ra/Rg) of 39.29 was observed for 200 ppm of ethanol gas. Additionally, very low response (τres = 14 s) and recovery (τrec = 30 s) times were observed for 100 ppm of ethanol.

Preparation and catalytic performance of copper-containing magnetic catalysts for degradation of azo dye (direct violet).

PubMed

Duan, Qiannan; Lee, Jianchao; Chen, Han; Zheng, Yunyun

2017-12-01

A novel magnetically separable magnetic activated carbon supporting-copper (MCAC) catalyst for catalytic wet peroxide oxidation (CWPO) was prepared by chemical impregnation. The prepared samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). The catalytic performance of the catalysts was evaluated by direct violet (D-BL) degradation in CWPO experiments. The influence of preparative and operational parameters (dipping conditions, calcination temperature, catalyst loading H 2 O 2 dosage, pH, reaction temperature, additive salt ions and initial D-BL concentration) on degradation performance of CWPO process was investigated. The resulting MCAC catalyst showed higher reusability in direct violet oxidation than the magnetic activated carbon (MAC). Besides, dynamic tests also showed the maximal degradation rate reached 90.16% and its general decoloring ability of MCAC was 34 mg g -1 for aqueous D-BL.

Effect of overcharge on Li(Ni 0.5Mn 0.3Co 0.2)O 2/graphite lithium ion cells with poly(vinylidene fluoride) binder. III — Chemical changes in the cathode

DOE PAGES

Bareno, Javier; Dietz Rago, Nancy; Dogan, Fulya; ...

2018-01-17

Here, 1.5 Ah pouch cells based on Li(Ni 0.5Mn 0.3Co 0.2)O 2 cathodes and graphite anodes, both containing poly (vinylidene fluoride) (PVDF) binders, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state of charge (SOC), at which point they vented. The cells were subsequently discharged to 0% SOC and disassembled under an inert atmosphere for characterization. A combination of X-ray photoelectron spectroscopy (XPS), scanning-electron microscopy (SEM), energy-dispersive spectroscopy (EDS), 6Li SSNMR, and X-ray diffraction (XRD) analysis of the NMC532 cathodes indicates the formation of a thin C- and O-rich cathode electrolyte interphase layer, progressive Li lossmore » above 140% SOC, and retention of the bulk crystal structure at all states of charge.« less

Structure, wettability and thermal degradation of new fluoro-oligomer modified nanoclays.

PubMed

Valsecchi, R; Viganò, M; Levi, M; Turri, S

2008-04-01

Quaternary ammonium salts based on monofunctionalized Perfluoropolyether (PFPE) oligomers were synthesized and used for the cation exchange process of sodium Montmorillonite nanoclays. The new fluoromodified nanoclays were characterized through X-rays diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), termogravimetric analysis (TGA), differential scanning calorimetry (DSC), electronic microscopy (SEM-EDS), and contact angle measurements (CA). In particular XRD showed rather complex patterns (presence of higher order reflections) which allowed the calculation of basal spacings, regularly increasing with the molecular weight of the fluorinated macrocation. Both IR and SEM confirmed the presence of fluorinated segments at clays interface, while TGA showed a limited thermal stability with an onset of degradation temperature which seems not dependent on the molecular weight of the macrocation. CA measurements showed a peculiar behaviour, with evident dynamic hysteresis phenomena and surface tension components quite different from those of commercially available, organomodified clays.

Synthesis and characterization of blue fluorescent surface modified nano-graphene oxide flakes as a pH-sensitive drug delivery system

NASA Astrophysics Data System (ADS)

Hashemi, Hamed; Namazi, Hassan

2018-07-01

A new blue fluorescent surface modified graphene oxide (GO) by 6-(5-bromothiophen-2-yl) benzo[c][1,2,5]selenadiazole-5-carboxylic acid (TB) denoted as (GO-TB) was synthesized. The obtained hybrid was characterized by Scanning Electron Microscope (SEM/EDS); Brunauer-Emmett-Teller (BET); X-Ray Diffraction Spectroscopy (XRD); X-Ray Photoelectron Spectroscopy (XPS); UV-Vis Absorption Spectroscopy, and Fourier Transformed Infrared Spectroscopy (FTIR). The synthesized TB moiety displayed orange emission around 590 nm, while GO-TB exhibited a blue photoluminescence around 431 and 159 nm blue shift of photoluminescence. Doxorubicin immobilized on the hybrid surface up to 93%, and the release behavior in three different pHs was investigated. The release profile indicated a pH-dependent liberation with Fickian diffusion mechanism. The cytotoxicity of the hybrid was studied and the IC50 value for the hybrid was 5.16 µg/ml.

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS2 Nanoparticles

PubMed Central

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev

2018-01-01

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS2 (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end. PMID:29495394

Influence of defect luminescence and structural modification on the electrical properties of Magnesium Doped Zinc Oxide Nanorods

NASA Astrophysics Data System (ADS)

Santoshkumar, B.; Biswas, Amrita; Kalyanaraman, S.; Thangavel, R.; Udayabhanu, G.; Annadurai, G.; Velumani, S.

2017-06-01

Magnesium doped zinc oxide nanorod arrays on zinc oxide seed layers were grown by hydrothermal method. X-ray diffraction (XRD) patterns revealed the growth orientation along the preferential (002) direction. The hexagonal morphology was revealed from the field emission scanning electron microscope (FESEM) images. The elemental composition of the samples was confirmed by energy dispersive x-ray analysis spectra (EDS) and mapping dots. Carrier concentration, resistivity and mobility of the samples were obtained by Hall measurements. I-V characteristic curve confirmed the increase in resistivity upon doping. Photoluminescence (PL) spectra exposed the characteristic of UV emission along with defect mediated visible emission in the samples. Electrochemical impedance spectroscopy and cyclic voltammetry were undertaken to study the charge transport property. Owing to the change in the structural parameters and defect concentration the electrical properties of the doped samples were altered.

Sintering and microstructure of silicon carbide ceramic with Y3Al5O12 added by sol-gel method*

PubMed Central

Guo, Xing-zhong; Yang, Hui

2005-01-01

Silicon carbide (SiC) ceramic with YAG (Y3Al5O12) additive added by sol-gel method was liquid-phase sintered at different sintering temperatures, and the sintering mechanism and microstructural characteristics of resulting silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental distribution of surface (EDS). YAG (yttrium aluminum garnet) phase formed before the sintering and its uniform distribution in the SiC/YAG composite powder decreased the sintering temperature and improved the densification of SiC ceramic. The suitable sintering temperature was 1860 °C with the specimen sintered at this temperature having superior sintering and mechanical properties, smaller crystal size and fewer microstructure defects. Three characteristics of improved toughness of SiC ceramic with YAG added by sol-gel method were microstructural densification, main-crack deflection and crystal ‘bridging’. PMID:15682507

Evaluation of Microstructure and Mechanical Properties of Al-TiC Metal Matrix Composite Prepared by Conventional, Microwave and Spark Plasma Sintering Methods

PubMed Central

Ghasali, Ehsan; Fazili, Ali; Alizadeh, Masoud; Shirvanimoghaddam, Kamyar; Ebadzadeh, Touradj

2017-01-01

In this research, the mechanical properties and microstructure of Al-15 wt % TiC composite samples prepared by spark plasma, microwave, and conventional sintering were investigated. The sintering process was performed by the speak plasma sintering (SPS) technique, microwave and conventional furnaces at 400 °C, 600 °C, and 700 °C, respectively. The results showed that sintered samples by SPS have the highest relative density (99% of theoretical density), bending strength (291 ± 12 MPa), and hardness (253 ± 23 HV). The X-ray diffraction (XRD) investigations showed the formation of TiO2 from the surface layer decomposition of TiC particles. Scanning electron microscopy (SEM) micrographs demonstrated uniform distribution of reinforcement particles in all sintered samples. The SEM/EDS analysis revealed the formation of TiO2 around the porous TiC particles. PMID:29088114

Effect of overcharge on Li(Ni0.5Mn0.3Co0.2)O2/graphite lithium ion cells with poly(vinylidene fluoride) binder. III - Chemical changes in the cathode

NASA Astrophysics Data System (ADS)

Bareño, Javier; Dietz Rago, Nancy; Dogan, Fulya; Graczyk, Donald G.; Tsai, Yifen; Naik, Seema R.; Han, Sang-Don; Lee, Eungje; Du, Zhijia; Sheng, Yangping; Li, Jianlin; Wood, David L.; Steele, Leigh Anna; Lamb, Joshua; Spangler, Scott; Grosso, Christopher; Fenton, Kyle; Bloom, Ira

2018-05-01

1.5 Ah pouch cells based on Li(Ni0.5Mn0.3Co0.2)O2 cathodes and graphite anodes, both containing poly (vinylidene fluoride) (PVDF) binders, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state of charge (SOC), at which point they vented. The cells were subsequently discharged to 0% SOC and disassembled under an inert atmosphere for characterization. A combination of X-ray photoelectron spectroscopy (XPS), scanning-electron microscopy (SEM), energy-dispersive spectroscopy (EDS), 6Li SSNMR, and X-ray diffraction (XRD) analysis of the NMC532 cathodes indicates the formation of a thin C- and O-rich cathode electrolyte interphase layer, progressive Li loss above 140% SOC, and retention of the bulk crystal structure at all states of charge.

Novel Co(OH)2 with cotton-like structure as anode material for alkaline secondary batteries

NASA Astrophysics Data System (ADS)

Zhao, W.; Liao, Y. L.; Qiu, S. J.; Chu, H. L.; Zou, Y. J.; Xiang, C. L.; Zhang, H. Z.; Xu, F.; Sun, L. X.

2018-01-01

The cotton-like Co(OH)2 (S-Co(OH)2) was successfully synthesized and its electrochemical performance was systematically investigated. S-Co(OH)2 was prepared through the “destruction” of the newly formed colloid Co(OH)2 by the reduction using sodium borohydride. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Used as an anode material for alkaline secondary batteries, S-Co(OH)2 sample exhibited better cycle stability, higher electrochemical capacity, and higher rate performance than those of conventional β-Co(OH)2. At a discharge current density of 100 mA/g, the initial discharge capacity of S-Co(OH)2 is 549.3 mAh/g and the discharge capacity is still sustained to be 329.2 mAh/g after 100 charge-discharge cycles with a capacity retention of 59.9%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apaydin, Ramazan Oguzhan; Ebin, Burcak; Gurmen, Sebahattin

Copper-Nickel (CuNi) nanostructured alloy particles were produced by Ultrasonic Spray Pyrolysis and Hydrogen Reduction Method (USP-HR) from high purity copper and nickel nitrate aqueous solutions. The effect of the precursor solution in the range of 0.1 and 0.5 mol/L on the morphology and crystallite size of CuNi nanoparticles were investigated under 2 h running time, 700 °C operating temperature and 0.5 L/min H{sub 2} flow rate. Particle size, morphology, composition and crystallite structure were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). Particle characterization studies show that nanostructured alloy particles have cubic crystal structuremore » and they are in submicron size range with spherical morphology. The crystallite sizes of the particles calculated with Scherrer formula are 40 and 34 nm and average particles sizes observed from the SEM images are 300 and 510 nm for each experiment respectively.« less

Influence of the Additives and The pH On the Cobalt-Molybdenum (Co-Mo) Alloy Electrodeposited On n-TypeSilicon

NASA Astrophysics Data System (ADS)

Fekih, Z.; Ghellai, N.; Fortas, G.; Chiboub, N.; Sam, S.; Chabanne-sari, N. E.; Gabouze, N.

In this work, thin films of metal alloys (Co-Mo) have been electrodeposited onto silicon (Si) surface. The effects of two different additives (H3BO3 and Na2CO3) and the pH of the solution on the electrochemically deposited films (morphology, stochiometry…) have been investigated. The properties of the deposits were characterized by using X-Rays Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The results show that the morphology and the film composition depend on both the pH of the solution and the additives. The presence of boric acid favors the Mo deposition. Crack-free homogeneous deposits with a low percentage of molybdenum can be easily obtained from high pH bath. The deposits were shown to exhibits a good crystalline structure.

Effect of overcharge on Li(Ni 0.5Mn 0.3Co 0.2)O 2/graphite lithium ion cells with poly(vinylidene fluoride) binder. III — Chemical changes in the cathode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bareno, Javier; Dietz Rago, Nancy; Dogan, Fulya

Here, 1.5 Ah pouch cells based on Li(Ni 0.5Mn 0.3Co 0.2)O 2 cathodes and graphite anodes, both containing poly (vinylidene fluoride) (PVDF) binders, were systematically overcharged to 100, 120, 140, 160, 180, and 250% state of charge (SOC), at which point they vented. The cells were subsequently discharged to 0% SOC and disassembled under an inert atmosphere for characterization. A combination of X-ray photoelectron spectroscopy (XPS), scanning-electron microscopy (SEM), energy-dispersive spectroscopy (EDS), 6Li SSNMR, and X-ray diffraction (XRD) analysis of the NMC532 cathodes indicates the formation of a thin C- and O-rich cathode electrolyte interphase layer, progressive Li lossmore » above 140% SOC, and retention of the bulk crystal structure at all states of charge.« less

Study of radiation induced effects in the luminescence of nanostructured Al2O3: Yb, Er crystals

NASA Astrophysics Data System (ADS)

Gonçalves, K. A.; Bitencourt, J. F. S.; Mittani, J. C. R.; Tatumi, S. H.

2010-11-01

Alumina crystals doped with Yb and Er were obtained by sol gel process and their morphologies and luminescence properties were discussed. Nanocrystals formations composed by Er2O3, Yb2O3 e Yb3Al5O12 were observed by TEM images, EDS, electron beam diffraction and XRD, at the surface of the alumina grains. The size of the nanocrystals were of about (36±2) nm and (182±8) nm for the samples calcinated at 1200oC and 1600oC, respectively. The sample codoped with 1mol% of Er and 2 mol% of Yb supplied the best results for Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). The growth intensity of dosimetric TL peak at 205oC was linear with gamma radiation doses and the same behavior was observed in OSL results.

Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

NASA Technical Reports Server (NTRS)

Wiesner, Valerie L.; Bansal, Narottam P.

2015-01-01

The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment.

Adsorption Studies of Gadolinium ion on Graphitic Carbon Nitride

NASA Astrophysics Data System (ADS)

Kuila, S. K.; Kundu, T. K.

2018-03-01

Bulk graphitic carbon nitride (g-C3N4) is synthesized by thermal decomposition of urea and used as an adsorbent for gadolinium ion (Gd3+) from aqueous solution. Adsorption capacity of g-C3N4 is found to be influenced by initial Gd3+ concentration, solution pH and contact time. Adsorbed Gd3+is separated from g-C3N4 by ultracentrifuge. Initial and Gd ion accumulated g-C3N4 adsorbent are characterized by X-ray diffraction technique (XRD) for phase identification, UV-visible and Fourier transform infrared (FTIR) spectroscopy for adsorption characteristics and optical property, scanning electron microscopy (SEM) for morphological behaviour along with energy dispersive X-ray spectroscopy (EDS) for elemental study. HNO3(0.1M), NaOH (0.1M) and de-ionized water are used for desorption and around 97% quantitative recovery of Gd ion is observed.

Modification of carbon composites by nanoceramic compounds

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzebski, W.; Długoń, E.; Stoch, G. J.; Błażewicz, S.; Adamczyk, A.; Tatarzyńska, K.

2005-06-01

Carbon-carbon composites (C/C) exhibit excellent high-temperature mechanical properties but their air oxidation limits their use at temperatures above 500 °C to inert atmosphere. Variety of coatings has been used to protect C/C composites from oxidation. In this work C/C composite substrates were covered with ceramic multilayer coats by electrophoretic deposition from ceramic sols such as silica sol, alumina sol and silica-lumina sol. Sol particles were of nano-sized dimensions. Deposited coats were annealed at 900-1500 °C. Oxidation tests at 600 °C reveal that the best protection of C/C composite against oxidation gives the multilayer coat formed by three or four electrophoretic depositions. The phase composition in the final annealed layers was analyzed by Infrared spectroscopy (FTIR) and by X-ray diffraction analysis (XRD). Morphology and chemical composition was observed using Scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDS).

Preparation and characteristics of epoxy/clay/B4C nanocomposite at high concentration of boron carbide for neutron shielding application

NASA Astrophysics Data System (ADS)

Kiani, Mohammad Amin; Ahmadi, Seyed Javad; Outokesh, Mohammad; Adeli, Ruhollah; Mohammadi, Aghil

2017-12-01

In this research, the characteristics of the prepared samples in epoxy matrix by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscope (SEM) are evaluated. Meanwhile, the obtained mechanical properties of the specimen are investigated. Thermogravimetric analysis (TGA) is also employed to evaluate the thermal degradation of manufactured nanocomposites. The thermal neutron absorption properties of nanocomposites containing 3 wt% of montmorillonite nanoclay (closite30B) have been studied experimentally, using an Am-Be point source. Mechanical tests reveal that the higher B4C concentrations, the more tensile strengths, but lower Young's modulus in all samples under consideration. TGA analysis also shows that thermal stability of the nanocomposite, increases in presence of B4C. Finally, neutron absorption analysis shows that increasing the B4C concentration leads to a nonlinearly build-up of neutron absorption cross section.

Analytical Investigation Of Pigments, Ground Layer And Media Of Cartonnage Fragments From Greek Roman Period

NASA Astrophysics Data System (ADS)

Afifi, Hala. A. M.

Some cartonnage fragments from Hawara, Fayoum Excavation were examined to identify pigments, media and grounds. It belonged to the Greek-Roman period. They were studied by X-ray diffraction (XRD), Energy dispersive X ray analysis (EDS) equipped with Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). These techniques were used to identify the composition and morphology of grounds, nature of pigments and media used in cartonnage fragments. The coarse ground layer was composed of calcite and traces of quartz. The fine ground layer used under the pigments directly was composed of calcite only. Carbon black was used as black pigment while lead oxide as red pigment, showing the influence of Roman and Greek pigments on Egyptian art in these later periods. Blue colorant was identified as cuprorivaite and yellow pigment was goethite. Animal glue was used in the four pigments as medium colored.

Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

NASA Astrophysics Data System (ADS)

Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

2016-08-01

The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

NASA Astrophysics Data System (ADS)

Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.

2017-06-01

An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

Preparation of magnetic and bioactive calcium zinc iron silicon oxide composite for hyperthermia treatment of bone cancer and repair of bone defects.

PubMed

Jiang, Yumin; Ou, Jun; Zhang, Zhanhe; Qin, Qing-Hua

2011-03-01

In this paper, a calcium zinc iron silicon oxide composite (CZIS) was prepared using the sol-gel method. X-ray diffraction (XRD) was then employed to test the CZIS composite. The results from the test showed that the CZIS had three prominent crystalline phases: Ca(2)Fe(1.7)Zn(0.15)Si(0.15)O(5), Ca(2)SiO(4), and ZnFe(2)O(4). Calorimetric measurements were then performed using a magnetic induction furnace. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were conducted to confirm the growth of a precipitated hydroxyapatite phase after immersion in simulated body fluid (SBF). Cell culture experiments were also carried out, showing that the CZIS composite more visibly promoted osteoblast proliferation than ZnFe(2)O(4) glass ceramic and HA, and osteoblasts adhered and spread well on the surfaces of composite samples.

Biodiesel production from palm oil using calcined waste animal bone as catalyst.

PubMed

Obadiah, Asir; Swaroopa, Gnanadurai Ajji; Kumar, Samuel Vasanth; Jeganathan, Kenthorai Raman; Ramasubbu, Alagunambi

2012-07-01

Waste animal bones was employed as a cost effective catalyst for the transesterification of palm oil. The catalyst was calcined at different temperatures to transform the calcium phosphate in the bones to hydroxyapatite and 800 °C was found to give the best yield of biodiesel. The catalyst was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and Fourier transform infrared spectrometry (FT-IR). Under the optimal reaction conditions of 20 wt.% of catalyst, 1:18 oil to methanol molar ratio, 200 rpm of stirring of reactants and at a temperature of 65 °C, the methyl ester conversion was 96.78% and it was achieved in 4h. The catalyst performed equally well as the laboratory-grade CaO. Animal bone is therefore a useful raw material for the production of a cheap catalyst for transesterification. Copyright © 2012 Elsevier Ltd. All rights reserved.

Internet access and electronic communication among families in an urban pediatric emergency department.

PubMed

Saidinejad, Mohsen; Teach, Stephen J; Chamberlain, James M

2012-06-01

The Internet may represent an opportunity for health care providers in the emergency department (ED) to deliver discharge instructions and after-care educational materials electronically to patients and their caregivers. The objectives of this study were to determine the prevalence of Internet access and use among caregivers of children who visit the ED and to evaluate their interest in receiving after-care communication and educational material electronically. We distributed a self-administered survey to a convenience sample of English-speaking caregivers of children who presented to the ED of an urban, academic, pediatric hospital during November and December 2009. The survey was distributed to and completed by 509 English-speaking respondents. Of the participants, 423 (83.1%) of 509 identified themselves as black/African American, and 397 (77.9%) of 509 were publicly insured. Of the participants, 503 of 509 (98.9%; 95% confidence interval [CI], 97.9%-99.8%) reported that they have access to the Internet. Of the participants with Internet access, 312 of 503 (62.0%; 95% CI, 57.8%-66.3%) have access at home, 166 of 503 (33.0%; 95% CI, 28.9%-33.1%) have access at work, and 112 of 503 (22.3%; 95% CI, 18.6%-25.9%) have access by mobile phone. When asked about electronic communication and social networking, 483 of 503 (96.0%; 95% CI, 94.3%-97.7%) have an e-mail account, and 304 of 503 (60.4%; 95% CI, 56.2%-64.7%) have a Facebook account. Furthermore, 353 of 503 (70.1%; 95% CI, 66.2%-74.2%) reported accessing the Internet daily, whereas 128 of 503 (25.4%; 95% CI, 21.6%-29.3%) access the Internet at least 2 to 6 times per week. Among all respondents, interest in receiving communication from the ED only electronically was expressed by 259 of 509 participants (50.9%; 95% CI, 46.5%-55.2%). Approximately one third of the participants (173/509 [34%; 95% CI, 29.9%-38.1%]) expressed interest in an electronic channel for communication between the ED and their child's patient primary care provider. In this predominantly minority and economically disadvantaged population of caregivers presenting to an urban pediatric ED, a large majority reported regular access to the Internet and willingness and ability to receive communication from the ED via electronic means.

University of Iowa at TREC 2008 Legal and Relevance Feedback Tracks

DTIC Science & Technology

2008-11-01

Fellbaum, C, [ed.]. Wordnet: An Electronic Lexical Database. Cambridge : MIT Press, 1998. [3] Salton , G. (ed) (1971), The SMART Retrieval System...learning tools and techniques. 2nd Edition. San Francisco : Morgan Kaufmann, 2005. [5] Platt, J . Machines using Sequential Minimal Optimization. [ed.] B

Scanning Electron Microscopic Hair Shaft Analysis in Ectodermal Dysplasia Syndromes.

PubMed

Hirano-Ali, Stefanie A; Reed, Ashley M; Rowan, Brandon J; Sorrells, Timothy; Williams, Judith V; Pariser, David M; Hood, Antoinette F; Salkey, Kimberly

2015-01-01

The objective of the current study was to catalog hair shaft abnormalities in individuals with ectodermal dysplasia (ED) syndromes using scanning electron microscopy (SEM) and to compare the findings with those in unaffected controls. This is the second of a two-part study, the first of which used light microscopy as the modality and was previously published. Scanning electron microscopy was performed in a blinded manner on hair shafts from 65 subjects with seven types of ED syndromes and 41 unaffected control subjects. Assessment was performed along the length of the shaft and in cross section. Hair donations were collected at the 28th Annual National Family Conference held by the National Foundation for Ectodermal Dysplasia. Control subjects were recruited from a private dermatology practice and an academic children's hospital outpatient dermatology clinic. SEM identified various pathologic hair shaft abnormalities in each type of ED and in control patients. When hairs with all types of ED were grouped together and compared with those of control patients, the difference in the presence of small diameter and shallow and deep grooves was statistically significant (p < 0.05). When the EDs were separated according to subtype, statistically significant findings were also seen. SEM is a possible adjuvant tool in the diagnosis of ED syndromes. There are significant differences, with high specificity, between the hairs of individuals with ED and those of control subjects and between subtypes. © 2015 Wiley Periodicals, Inc.

Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR

NASA Astrophysics Data System (ADS)

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-01

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO4·KOH·H2O or more accurately as KCd2(CrO4)2(H3O2) illustrating the μ-H3O2- species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V).

Characterisation of the rare cadmium chromate pigment in a 19th century tube colour by Raman, FTIR, X-ray and EPR.

PubMed

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-15

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO 4 ·KOH·H 2 O or more accurately as KCd 2 (CrO 4 ) 2 (H 3 O 2 ) illustrating the μ-H 3 O 2 - species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V). Copyright © 2016 Elsevier B.V. All rights reserved.

Morphology and magnetic characterisation of aluminium substituted yttrium-iron garnet nanoparticles prepared using sol gel technique.

PubMed

Yahya, Noorhana; Al Habashi, Ramadan Masoud; Koziol, Krzysztof; Borkowski, Rafal Dunin; Akhtar, Majid Niaz; Kashif, Muhammad; Hashim, Mansor

2011-03-01

Aluminum substituted yttrium iron garnet nano particles with compositional variation of Y(3.0-x) A1(x)Fe5O12, where x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 were prepared using sol gel technique. The X-ray diffraction results showed that the best garnet phase appeared when the sintering temperature was 800 degrees C. Nano-crystalline particles with high purity and sizes ranging from 20 to 100 nm were obtained. It was found that the aluminum substitution had resulted in a sharp fall of the d-spacing when x = 2, which we speculated is due to the preference of the aluminum atoms to the smaller tetrahedron and octahedron sites instead of the much larger dodecahedron site. High resolution transmission electron microscope (HRTEM) and electron diffraction (ED) patterns showed single crystal nanoparticles were obtained from this method. The magnetic measurement gave moderate values of initial permeability; the highest value of 5.3 was shown by sample Y3Fe5O12 at more than 100 MHz which was attributed to the morphology of the microstructure which appeared to be homogeneous. This had resulted in an easy movement of domain walls. The substitution of aluminum for yttrium is speculated to cause a cubic to rhombodedral structural change and had weakened the super-exchange interactions thus a fall of real permeability was observed. This might have created a strain in the sub-lattices and had subsequently caused a shift of resonance frequencies to more than 1.8 GHz when x > 0.5.

The Heisenberg Uncertainty Principle Demonstrated with An Electron Diffraction Experiment

ERIC Educational Resources Information Center

Matteucci, Giorgio; Ferrari, Loris; Migliori, Andrea

2010-01-01

An experiment analogous to the classical diffraction of light from a circular aperture has been realized with electrons. The results are used to introduce undergraduate students to the wave behaviour of electrons. The diffraction fringes produced by the circular aperture are compared to those predicted by quantum mechanics and are exploited to…

High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Feichao; Liu, Shengguang; Zhu, Pengfei

2014-08-15

A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities inmore » various areas of sciences.« less

High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun.

PubMed

Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao; Zhang, Jie; Cao, Jianming

2014-08-01

A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities in various areas of sciences.

Total-scattering pair-distribution function of organic material from powder electron diffraction data

DOE PAGES

Gorelik, Tatiana E.; Billinge, Simon J. L.; Schmidt, Martin U.; ...

2015-04-01

This paper shows for the first time that pair-distribution function analyses can be carried out on organic and organo-metallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction (SAED) and nanodiffraction in transmission electron microscopy (TEM) or nanodiffraction in scanning transmission electron microscopy (STEM) modes. The methods were demonstrated on organo-metallic complexes (chlorinated and unchlorinated copper-phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering datamore » and avoiding beam-damage of the sample are possible to resolve.« less

Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

PubMed

Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

2017-12-01

In this paper, N-doped TiO 2 (N-TiO 2 ) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO 2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO 2 . To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO 2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO 2 than un-doped TiO 2 . The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO 2 than to un-doped TiO 2 . Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO 2 than that on un-doped TiO 2 .

Phase Imaging: A Compressive Sensing Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, Sebastian; Stevens, Andrew; Browning, Nigel D.

Since Wolfgang Pauli posed the question in 1933, whether the probability densities |Ψ(r)|² (real-space image) and |Ψ(q)|² (reciprocal space image) uniquely determine the wave function Ψ(r) [1], the so called Pauli Problem sparked numerous methods in all fields of microscopy [2, 3]. Reconstructing the complete wave function Ψ(r) = a(r)e-iφ(r) with the amplitude a(r) and the phase φ(r) from the recorded intensity enables the possibility to directly study the electric and magnetic properties of the sample through the phase. In transmission electron microscopy (TEM), electron holography is by far the most established method for phase reconstruction [4]. Requiring a highmore » stability of the microscope, next to the installation of a biprism in the TEM, holography cannot be applied to any microscope straightforwardly. Recently, a phase retrieval approach was proposed using conventional TEM electron diffractive imaging (EDI). Using the SAD aperture as reciprocal-space constraint, a localized sample structure can be reconstructed from its diffraction pattern and a real-space image using the hybrid input-output algorithm [5]. We present an alternative approach using compressive phase-retrieval [6]. Our approach does not require a real-space image. Instead, random complimentary pairs of checkerboard masks are cut into a 200 nm Pt foil covering a conventional TEM aperture (cf. Figure 1). Used as SAD aperture, subsequently diffraction patterns are recorded from the same sample area. Hereby every mask blocks different parts of gold particles on a carbon support (cf. Figure 2). The compressive sensing problem has the following formulation. First, we note that the complex-valued reciprocal-space wave-function is the Fourier transform of the (also complex-valued) real-space wave-function, Ψ(q) = F[Ψ(r)], and subsequently the diffraction pattern image is given by |Ψ(q)|2 = |F[Ψ(r)]|2. We want to find Ψ(r) given a few differently coded diffraction pattern measurements yn = |F[HnΨ(r)]|2, where the matrices Hn encode the mask structure of the aperture. This is a nonlinear inverse problem, but has been shown to be solvable even in the underdetermined case [6]. Since each diffraction pattern yn contains diffraction information from selected regions of the same sample, the differences in each pattern contain local phase information, which can be combined to form a full estimate of the real-space wave-function[7]. References: [1] W. Pauli in “Die allgemeinen Prinzipien der Wellenmechanik“, ed. H Geiger and W Scheel, (Julius Springer, Berlin). [2] A. Tonomura, Rev. Mod. Phys. 59 (1987), p. 639. [3] J. Miao et al, Nature 400 (1999), p. 342. [4] H. Lichte et al, Annu. Rev. Mater. Res. 37 (2007), p. 539. [5] J. Yamasaki et al, Appl. Phys. Lett. 101 (2012), 234105. [6] P Schniter and S Rangan. Signal Proc., IEEE Trans. on. 64(4), (2015), pp. 1043. [7] Supported by the Chemical Imaging, Signature Discovery, and Analytics in Motion initiatives at PNNL. PNNL is operated by Battelle Memorial Inst. for the US DOE; contract DE-AC05-76RL01830.« less

Photocatalytic performance of Ag doped SnO2 nanoparticles modified with curcumin

NASA Astrophysics Data System (ADS)

Vignesh, K.; Hariharan, R.; Rajarajan, M.; Suganthi, A.

2013-07-01

Visible light active Ag doped SnO2 nanoparticles modified with curcumin (Cur-Ag-SnO2) have been prepared by a combined precipitation and chemical impregnation route. The optical properties, phase structures and morphologies of the as-prepared nanoparticles were characterized using UV-visible diffuse reflectance spectra (UV-vis-DRS), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The surface area was measured by Brunauer. Emmett. Teller (B.E.T) analysis. Compared to bare SnO2, the surface modified photocatalysts (Ag-SnO2 and Cur-Ag-SnO2) showed a red shift in the visible region. The photocatalytic activity was monitored via the degradation of rose bengal (RB) dye and the results revealed that Cur-Ag-SnO2 shows better photocatalytic activity than that of Ag-SnO2 and SnO2. The superior photocatalytic activity of Cur-Ag-SnO2 could be attributed to the effective electron-hole separation by surface modification. The effect of photocatalyst concentration, initial dye concentration and electron scavenger on the photocatalytic activity was examined in detail. Furthermore, the antifungal activity of the photocatalysts and the reusability of Cur-Ag-SnO2 were tested.

Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

2003-01-01

Advanced oxide thermal barrier coatings have been developed by incorporating multi-component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma-sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), electron energy-loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia- yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging from 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

Formation and morphology of Zn(2)Ti(3)O(8) powders using hydrothermal process without dispersant agent or mineralizer.

PubMed

Wang, Cheng-Li; Hwang, Weng-Sing; Chang, Kuo-Ming; Ko, Horng-Huey; Hsi, Chi-Shiung; Huang, Hong-Hsin; Wang, Moo-Chin

2011-01-28

Synthesis of Zn(2)Ti(3)O(8) powders for attenuating UVA using TiCl(4), Zn(NO(3))(2)·6H(2)O and NH(4)OH as precursor materials by hydrothermal process has been investigated. The X-ray diffractometry (XRD) results show the phases of ZnO, anatase TiO(2) and Zn(2)Ti(3)O(8) coexisted when the zinc titanate powders were calcined at 600 °C for 1 h. When calcined at 900 °C for 1 h, the XRD results reveal the existence of ZnO, Zn(2)TiO(4), rutile TiO(2) and ZnTiO(3). Scanning electron microscope (SEM) observations show extensive large agglomeration in the samples. Transmission electron microscope (TEM) and electron diffraction (ED) examination results indicate that ZnTiO(3) crystallites formed with a size of about 5 nm on the matrix of plate-like ZnO when calcined at 700 °C for 1 h. The calcination samples have acceptable absorbance at a wavelength of 400 nm, indicating that the zinc titanate precursor powders calcined at 700 °C for 1 h can be used as an UVA-attenuating agent.

Formation and Morphology of Zn2Ti3O8 Powders Using Hydrothermal Process without Dispersant Agent or Mineralizer

PubMed Central

Wang, Cheng-Li; Hwang, Weng-Sing; Chang, Kuo-Ming; Ko, Horng-Huey; Hsi, Chi-Shiung; Huang, Hong-Hsin; Wang, Moo-Chin

2011-01-01

Synthesis of Zn2Ti3O8 powders for attenuating UVA using TiCl4, Zn(NO3)2·6H2O and NH4OH as precursor materials by hydrothermal process has been investigated. The X-ray diffractometry (XRD) results show the phases of ZnO, anatase TiO2 and Zn2Ti3O8 coexisted when the zinc titanate powders were calcined at 600 °C for 1 h. When calcined at 900 °C for 1 h, the XRD results reveal the existence of ZnO, Zn2TiO4, rutile TiO2 and ZnTiO3. Scanning electron microscope (SEM) observations show extensive large agglomeration in the samples. Transmission electron microscope (TEM) and electron diffraction (ED) examination results indicate that ZnTiO3 crystallites formed with a size of about 5 nm on the matrix of plate-like ZnO when calcined at 700 °C for 1 h. The calcination samples have acceptable absorbance at a wavelength of 400 nm, indicating that the zinc titanate precursor powders calcined at 700 °C for 1 h can be used as an UVA-attenuating agent. PMID:21541035

Influence of Sc on microstructure and mechanical properties of Al-Si-Mg-Cu-Zr alloy

NASA Astrophysics Data System (ADS)

Li, Yukun; Du, Xiaodong; Zhang, Ya; Zhang, Zhen; Fu, Junwei; Zhou, Shi'ang; Wu, Yucheng

2018-02-01

In the present study, the effects of Mg, Cu, Sc and Zr combined additions on the microstructure and mechanical properties of hypoeutectic Al-Si cast alloy were systematically investigated. Characterization techniques such as optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron back-scatter diffraction (EBSD), atomic force microscopy (AFM), transmission electron microscope (TEM), Brinell hardness tester and universal testing machine were employed to analyze the microstructure and mechanical properties. The results showed that Sc served as modifier on the microstructure of Al-3Si-0.45Mg-0.45Cu-0.2Zr alloys, including modification of eutectic Si and grains. Extraordinarily, grain refinement was found to be related to the primary particles, which exhibited a close orientation to matrix. After T6 heat treatment, the grain structures were composed of nano-scaled secondary Al3(Sc, Zr) precipitates and spherical eutectic Si. Combined with T6 heat treatment, the highest hardness, yield strength, ultimate tensile strength and elongation were achieved in 0.56 wt.% Sc-modified alloy. Interestingly, the strength and ductility had a similar tendency. This paper demonstrated that combined additions of Mg, Cu, Sc and Zr could significantly improve the microstructure and performance of the hypoeutectic Al-Si cast alloy.

Facile fabrication of CuO-Pb2O3 nanophotocatalyst for efficient degradation of Rose Bengal dye under visible light irradiation

NASA Astrophysics Data System (ADS)

Kamaraj, Eswaran; Somasundaram, Sivaraman; Balasubramani, Kavitha; Eswaran, Muthu Prema; Muthuramalingam, Rajarajan; Park, Sanghyuk

2018-03-01

A p-type CuO/n-type Pb2O3 heterojunction photocatalyst was prepared by a simple wet chemical process and the photocatalytic ability was evaluated for the degradation of Rose Bengal (RB) under visible light irradiation. Synthesized nanocatalysts were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). The p-n heterojunction of CuO-Pb2O3 nanostructures can promote the light absorption capability of photocatalyst and charge separation of electron-hole pairs. Photodegradation assays showed that the addition of CuO effectively enhanced the photocatalytic activity of CuO-Pb2O3 under visible light irradiation (λmax > 420 nm). Compared with pure Pb2O3 and CuO, the CuO-Pb2O3 exhibited significantly enhanced photocatalytic degradation activity. The reaction rate constant of CuO-Pb2O3 is 0.092 min-1, which is much higher than those of CuO (0.073 min-1) and Pb2O3 (0.045 min-1).

Graphene-Supported Spinel CuFe2O4 Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media

PubMed Central

La, Duong Duc; Nguyen, Tuan Anh; Jones, Lathe A.; Bhosale, Sheshanath V.

2017-01-01

A graphene nanoplate-supported spinel CuFe2O4 composite (GNPs/CuFe2O4) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe2O4 composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe2O4 composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing. PMID:28587257

Paramagnetic Defects in Electron-Irradiated Yttria-Stabilized Zirconia: Effect of Yttria Content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah

2011-01-01

We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are stronglymore » enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 1 eV with subsequent defect re-arrangement.« less

X-ray diffraction and SEM study of kidney stones in Israel: quantitative analysis, crystallite size determination, and statistical characterization.

PubMed

Uvarov, Vladimir; Popov, Inna; Shapur, Nandakishore; Abdin, Tamer; Gofrit, Ofer N; Pode, Dov; Duvdevani, Mordechai

2011-12-01

Urinary calculi have been recognized as one of the most painful medical disorders. Tenable knowledge of the phase composition of the stones is very important to elucidate an underlying etiology of the stone disease. We report here the results of quantitative X-ray diffraction phase analysis performed on 278 kidney stones from the 275 patients treated at the Department of Urology of Hadassah Hebrew University Hospital (Jerusalem, Israel). Quantification of biominerals in multicomponent samples was performed using the normalized reference intensity ratio method. According to the observed phase compositions, all the tested stones were classified into five chemical groups: oxalates (43.2%), phosphates (7.7%), urates (10.3%), cystines (2.9%), and stones composed of a mixture of different minerals (35.9%). A detailed analysis of each allocated chemical group is presented along with the crystallite size calculations for all the observed crystalline phases. The obtained results have been compared with the published data originated from different geographical regions. Morphology and spatial distribution of the phases identified in the kidney stones were studied with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). This type of detailed study of phase composition and structural characteristics of the kidney stones was performed in Israel for the first time.

Photoluminescent properties of spider silk coated with Eu-doped nanoceria

NASA Astrophysics Data System (ADS)

Dmitrović, Svetlana; Nikolić, Marko G.; Jelenković, Branislav; Prekajski, Marija; Rabasović, Mihailo; Zarubica, Aleksandra; Branković, Goran; Matović, Branko

2017-02-01

Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO3)3) and ammonium hydroxide (NH4OH). Depending on the relationship between Ce3+ ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

Structure investigations of ferromagnetic Co-Ni-Al alloys obtained by powder metallurgy.

PubMed

Maziarz, W; Dutkiewicz, J; Lityńska-Dobrzyńska, L; Santamarta, R; Cesari, E

2010-03-01

Elemental powders of Co, Ni and Al in the proper amounts to obtain Co(35)Ni(40)Al(25) and Co(40)Ni(35)Al(25) nominal compositions were ball milled in a high-energy mill for 80 h. After 40 h of milling, the formation of a Co (Ni, Al) solid solution with f.c.c. structure was verified by a change of the original lattice parameter and crystallite size. Analytical transmission electron microscopy observations and X-ray diffraction measurements of the final Co (Ni, Al) solid solution showed that the crystallite size scattered from 4 to 8 nm and lattice parameter a = 0.36086 nm. The chemical EDS point analysis of the milled powder particles allowed the calculation of the e/a ratio and revealed a high degree of chemical homogeneity of the powders. Hot pressing in vacuum of the milled powders resulted in obtaining compacts with a density of about 70% of the theoretical one. An additional heat treatment increased the density and induced the martensitic transformation in a parent phase. Selected area diffraction patterns and dark field images obtained from the heat-treated sample revealed small grains around 300 nm in diameter consisting mainly of the ordered gamma phase (gamma'), often appearing as twins, and a small amount of the L1(0) ordered martensite.

Ultrafast electron diffraction optimized for studying structural dynamics in thin films and monolayers

PubMed Central

Badali, D. S.; Gengler, R. Y. N.; Miller, R. J. D.

2016-01-01

A compact electron source specifically designed for time-resolved diffraction studies of free-standing thin films and monolayers is presented here. The sensitivity to thin samples is achieved by extending the established technique of ultrafast electron diffraction to the “medium” energy regime (1–10 kV). An extremely compact design, in combination with low bunch charges, allows for high quality diffraction in a lensless geometry. The measured and simulated characteristics of the experimental system reveal sub-picosecond temporal resolution, while demonstrating the ability to produce high quality diffraction patterns from atomically thin samples. PMID:27226978

Dark-field imaging based on post-processed electron backscatter diffraction patterns of bulk crystalline materials in a scanning electron microscope.

PubMed

Brodusch, Nicolas; Demers, Hendrix; Gauvin, Raynald

2015-01-01

Dark-field (DF) images were acquired in the scanning electron microscope with an offline procedure based on electron backscatter diffraction (EBSD) patterns (EBSPs). These EBSD-DF images were generated by selecting a particular reflection on the electron backscatter diffraction pattern and by reporting the intensity of one or several pixels around this point at each pixel of the EBSD-DF image. Unlike previous studies, the diffraction information of the sample is the basis of the final image contrast with a pixel scale resolution at the EBSP providing DF imaging in the scanning electron microscope. The offline facility of this technique permits the selection of any diffraction condition available in the diffraction pattern and displaying the corresponding image. The high number of diffraction-based images available allows a better monitoring of deformation structures compared to electron channeling contrast imaging (ECCI) which is generally limited to a few images of the same area. This technique was applied to steel and iron specimens and showed its high capability in describing more rigorously the deformation structures around micro-hardness indents. Due to the offline relation between the reference EBSP and the EBSD-DF images, this new technique will undoubtedly greatly improve our knowledge of deformation mechanism and help to improve our understanding of the ECCI contrast mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

FAM20A Gene Mutation: Amelogenesis or Ectopic Mineralization?

PubMed

Lignon, Guilhem; Beres, Fleur; Quentric, Mickael; Rouzière, Stephan; Weil, Raphael; De La Dure-Molla, Muriel; Naveau, Adrien; Kozyraki, Renata; Dessombz, Arnaud; Berdal, Ariane

2017-01-01

Background and objective: FAM20A gene mutations result in enamel renal syndrome (ERS) associated with amelogenesis imperfecta (AI), nephrocalcinosis, gingival fibromatosis, and impaired tooth eruption. FAM20A would control the phosphorylation of enamel peptides and thus enamel mineralization. Here, we characterized the structure and chemical composition of unerupted tooth enamel from ERS patients and healthy subjects. Methods: Tooth sections were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF). Results: SEM revealed that prisms were restricted to the inner-most enamel zones. The bulk of the mineralized matter covering the crown was formed by layers with varying electron-densities organized into lamellae and micronodules. Tissue porosity progressively increased at the periphery, ending with loose and unfused nanonodules also observed in the adjoining soft tissues. Thus, the enamel layer covering the dentin in all ERS patients (except a limited layer of enamel at the dentino-enamel junction) displayed an ultrastructural globular pattern similar to one observed in ectopic mineralization of soft tissue, notably in the gingiva of Fam20a knockout mice. XRD analysis confirmed the existence of alterations in crystallinity and composition (vs. sound enamel). XRF identified lower levels of calcium and phosphorus in ERS enamel. Finally, EDS confirmed the reduced amount of calcium in ERS enamel, which appeared similar to dentin. Conclusion: This study suggests that, after an initial normal start to amelogenesis, the bulk of the tissue covering coronal dentin would be formed by different mechanisms based on nano- to micro-nodule aggregation. This evocated ectopic mineralization process is known to intervene in several soft tissues in FAM20A gene mutant.

Using a medical simulation center as an electronic health record usability laboratory

PubMed Central

Landman, Adam B; Redden, Lisa; Neri, Pamela; Poole, Stephen; Horsky, Jan; Raja, Ali S; Pozner, Charles N; Schiff, Gordon; Poon, Eric G

2014-01-01

Usability testing is increasingly being recognized as a way to increase the usability and safety of health information technology (HIT). Medical simulation centers can serve as testing environments for HIT usability studies. We integrated the quality assurance version of our emergency department (ED) electronic health record (EHR) into our medical simulation center and piloted a clinical care scenario in which emergency medicine resident physicians evaluated a simulated ED patient and documented electronically using the ED EHR. Meticulous planning and close collaboration with expert simulation staff was important for designing test scenarios, pilot testing, and running the sessions. Similarly, working with information systems teams was important for integration of the EHR. Electronic tools are needed to facilitate entry of fictitious clinical results while the simulation scenario is unfolding. EHRs can be successfully integrated into existing simulation centers, which may provide realistic environments for usability testing, training, and evaluation of human–computer interactions. PMID:24249778

Femtosecond gas phase electron diffraction with MeV electrons.

PubMed

Yang, Jie; Guehr, Markus; Vecchione, Theodore; Robinson, Matthew S; Li, Renkai; Hartmann, Nick; Shen, Xiaozhe; Coffee, Ryan; Corbett, Jeff; Fry, Alan; Gaffney, Kelly; Gorkhover, Tais; Hast, Carsten; Jobe, Keith; Makasyuk, Igor; Reid, Alexander; Robinson, Joseph; Vetter, Sharon; Wang, Fenglin; Weathersby, Stephen; Yoneda, Charles; Wang, Xijie; Centurion, Martin

2016-12-16

We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution.

Synthesis, structure and electrochemical properties of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedotov, Stanislav S.; Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow; Kuzovchikov, Sergey M.

2016-10-15

LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by {sup 57}Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F cathode material demonstrated a reversible activity of the Fe{sup 3+}/Fe{sup 2+} redox couple at the electrodemore » potential near 3.4 V and minor activity of the Co{sup 3+}/Co{sup 2+} redox couple over 5 V vs Li/Li{sup +}. The material exhibited the discharge capacity of more than 82% (theo.) regarding Fe{sup 3+}/Fe{sup 2+} in the 2.4÷4.6 V vs Li/Li{sup +} potential range. - Graphical abstract: The ball-polyhedral representation of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F crystal structure. The MO{sub 4}F{sub 2} units are depicted as blue octahedra, PO{sub 4} units as orange tetrahedra, sodium atoms are designated as yellow (Na1), lithium – red and brown (Li2, Li3 resp.), fluorine – green, oxygen – violet spheres. - Highlights: • Freeze-drying method was successfully applied to the synthesis of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F. • The crystal structure of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F was refined based on NPD and validated by ED and HRTEM. • LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F demonstrated a reversible Li de/intercalation in the 2.5÷4.6 V vs Li/Li{sup +} range.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biendicho, J.J.; The ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX Oxfordshire; Shafeie, S.

Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared in air (0.71≤x≤0.91) as well as in N{sub 2} (x=0.75 and 0.79) at 1573 K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3−δ=2.79(2) for x=0.75 to 3−δ=2.83(2) for x=0.91. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data shows high anisotropic atomic displacement parameter (ADP) for the oxygen atom resulting from a substantial cation and anion disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}more » reveal a modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5–390 K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm/K in air at 298–673 K. At 773–1173 K TEC increases up to 17.2 ppm/K due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673 K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ} (y=0.2, 0.33, 0.5) leads to cubic perovskites for all substituents with y=0.2. Their TECs are higher in comparison with un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. Only M=Ni has increased electrical conductivity compared to un-doped Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79}. - Graphical abstract: Oxygen-deficient ferrates with the cubic perovskite structure Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} were prepared both in air (0.71≤x≤0.91) and N{sub 2} (x=0.75 and 0.79) at 1573 K. Refinement of the crystal structure of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} using TOF neutron powder diffraction (NPD) data (S.G. Pm-3m, a=3.86455(3) Å; χ{sup 2}=6.71, R{sub p}=0.03; R{sub wp}=0.04) confirmed the cubic perovskite structure. The observed high anisotropic atomic displacement parameter for the oxygen atom indicates a substantial anion sublattice disorder. Electron diffraction (ED) and high-resolution electron microscopy (HREM) studies of Sr{sub 0.75}Y{sub 0.25}FeO{sub 2.79} show compositional modulation along 〈1 0 0〉{sub p} with G± ∼0.4〈1 0 0〉{sub p} indicating ordering of oxygen vacancies at the local scale. Highlights: ► Cubic perovskites Sr{sub x}Y{sub 1−x}FeO{sub 3−δ} (0.71≤x<0.91) were synthesized. ► Sr{sub 0.75}Y{sub 0.25}Fe{sub 1−y}M{sub y}O{sub 3−δ}, M=Cr, Mn, Ni were prepared. ► High-temperature conductivity properties and crystal structure were studied. ► High-temperature thermal expansion behavior was investigated.« less

A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

PubMed Central

Nederlof, Igor; van Genderen, Eric; Li, Yao-Wang; Abrahams, Jan Pieter

2013-01-01

When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e− Å−2), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins. PMID:23793148

Three-dimensional electron diffraction of plant light-harvesting complex

PubMed Central

Wang, Da Neng; Kühlbrandt, Werner

1992-01-01

Electron diffraction patterns of two-dimensional crystals of light-harvesting chlorophyll a/b-protein complex (LHC-II) from photosynthetic membranes of pea chloroplasts, tilted at different angles up to 60°, were collected to 3.2 Å resolution at -125°C. The reflection intensities were merged into a three-dimensional data set. The Friedel R-factor and the merging R-factor were 21.8 and 27.6%, respectively. Specimen flatness and crystal size were critical for recording electron diffraction patterns from crystals at high tilts. The principal sources of experimental error were attributed to limitations of the number of unit cells contributing to an electron diffraction pattern, and to the critical electron dose. The distribution of strong diffraction spots indicated that the three-dimensional structure of LHC-II is less regular than that of other known membrane proteins and is not dominated by a particular feature of secondary structure. ImagesFIGURE 1FIGURE 2 PMID:19431817

In-situ XRD and EDS method study on the oxidation behaviour of Ni-Cu sulphide ore.

PubMed

Li, Guangshi; Cheng, Hongwei; Xiong, Xiaolu; Lu, Xionggang; Xu, Cong; Lu, Changyuan; Zou, Xingli; Xu, Qian

2017-06-12

The oxidation mechanism of sulfides is the key issue during the sulphide-metallurgy process. In this study, the phase transformation and element migration were clearly demonstrated by in-situ laboratory-based X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS), respectively. The reaction sequence and a four-step oxidation mechanism were proposed and identified. The elemental distribution demonstrated that at a low temperature, the Fe atoms diffused outward and the Ni/Cu atoms migrated toward the inner core, whereas the opposite diffusion processes were observed at a higher temperature. Importantly, the unique visual presentation of the oxidation behaviour provided by the combination of in-situ XRD and EDS might be useful for optimising the process parameters to improve the Ni/Cu extraction efficiency during Ni-Cu sulphide metallurgy.

Imaging electronic motions by ultrafast electron diffraction

NASA Astrophysics Data System (ADS)

Shao, Hua-Chieh; Starace, Anthony F.

2017-08-01

Recently ultrafast electron diffraction and microscopy have reached unprecedented temporal resolution, and transient structures with atomic precision have been observed in various reactions. It is anticipated that these extraordinary advances will soon allow direct observation of electronic motions during chemical reactions. We therefore performed a series of theoretical investigations and simulations to investigate the imaging of electronic motions in atoms and molecules by ultrafast electron diffraction. Three prototypical electronic motions were considered for hydrogen atoms. For the case of a breathing mode, the electron density expands and contracts periodically, and we show that the time-resolved scattering intensities reflect such changes of the charge radius. For the case of a wiggling mode, the electron oscillates from one side of the nucleus to the other, and we show that the diffraction images exhibit asymmetric angular distributions. The last case is a hybrid mode that involves both breathing and wiggling motions. Owing to the demonstrated ability of ultrafast electrons to image these motions, we have proposed to image a coherent population transfer in lithium atoms using currently available femtosecond electron pulses. A frequency-swept laser pulse adiabatically drives the valence electron of a lithium atom from the 2s to 2p orbitals, and a time-delayed electron pulse maps such motion. Our simulations show that the diffraction images reflect this motion both in the scattering intensities and the angular distributions.

Incident-beam effects in electron-stimulated Auger-electron diffraction

NASA Astrophysics Data System (ADS)

Gao, Y.; Cao, Jianming

1991-04-01

We have examined incident-beam effects in electron-stimulated Auger-electron diffraction (AED) on a cleaved GaAs(110) surface. The results indicate that incident-beam diffraction is significant in an AED experiment, and that the dissipative nature of the incident beam in contributing to the Auger process must be accounted for. We have developed a qualitative model that describes the trend of the polar-angle dependence of the Auger intensity for both the incident and exit beams. In calculating the diffraction features, we used a zeroth-order approximation to simulate the dissipation of the incident beam, which is found to adequately describe the experimental data.

Impact of annealing on physical properties of e-beam evaporated polycrystalline CdO thin films for optoelectronic applications

NASA Astrophysics Data System (ADS)

Purohit, Anuradha; Chander, S.; Dhaka, M. S.

2017-04-01

An impact of annealing on the physical properties of polycrystalline CdO thin films is carried out in this study. CdO thin films of thickness 650 nm were fabricated on glass and indium tin oxide (ITO) substrates employing e-beam evaporation technique. The pristine thin films were annealed in air atmosphere at 250 °C, 400 °C and 550 °C for one hour followed by investigation of structural, optical, electrical and morphological properties along with elemental composition using X-ray diffraction (XRD), UV-Vis spectrophotometer, Fourier transform infrared (FTIR) spectrometer, source meter, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), respectively. XRD patterns confirmed the polycrystalline nature and cubic structure (with space group Fm 3 bar m) of the films. The crystallographic parameters are calculated and found to be influenced by the post-air annealing treatment. The optical study shows that direct band gap is ranging from 1.98 eV to 2.18 eV and found to be decreased with post-annealing. The refractive index and optical conductivity are also increased with annealing temperature. The current-voltage characteristics show ohmic behaviour of the annealed films. The surface morphology is observed to be improved with annealing and grain-size is increased as well as EDS spectrum confirmed the presence of cadmium (Cd) and oxygen (O) in the deposited films.

Zinc-Containing Hydroxyapatite Enhances Cold-Light-Activated Tooth Bleaching Treatment In Vitro

PubMed Central

Shi, Xinchang

2017-01-01

Cold-light bleaching treatment has grown to be a popular tooth whitening procedure in recent years, but its side effect of dental enamel demineralization is a widespread problem. The aim of this study was to synthesize zinc-substituted hydroxyapatite as an effective biomaterial to inhibit demineralization or increase remineralization. We synthesized zinc-substituted hydroxyapatite containing different zinc concentrations and analysed the product using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and energy dispersive spectrometer (EDS). The biological assessment of Zn-HA was conducted by CCK-8 assay and bacterial inhibition tests. pH cycling was performed to estimate the effect of Zn-HA on the enamel surface after cold-light bleaching treatment. The XRD, FTIR, and EDS results illustrated that zinc ions and hydroxyapatite combined in two forms: (1) Zn2+ absorbed on the surface of HA crystal and (2) Zn2+ incorporated into the lattice of HA. The results indicated that 2% Zn-HA, 4% Zn-HA, and 8% Zn-HA effectively inhibited the growth of bacteria yet showed poor biocompatibility, whereas 1% Zn-HA positively affected osteoblast proliferation. The XRD and scanning electron microscopy (SEM) results showed that the use of Zn-HA in pH cycling is obviously beneficial for enamel remineralization. Zinc-substituted hydroxyapatite could be a promising biomaterial for use in cold-light bleaching to prevent enamel demineralization. PMID:29159178

Titanium-35niobium alloy as a potential material for biomedical implants: In vitro study.

PubMed

de Andrade, Dennia Perez; de Vasconcellos, Luana Marotta Reis; Carvalho, Isabel Chaves Silva; Forte, Lilibeth Ferraz de Brito Penna; de Souza Santos, Evelyn Luzia; Prado, Renata Falchete do; Santos, Dalcy Roberto Dos; Cairo, Carlos Alberto Alves; Carvalho, Yasmin Rodarte

2015-11-01

Research on new titanium alloys and different surface topographies aims to improve osseointegration. The objective of this study is to analyze the behavior of osteogenic cells cultivated on porous and dense samples of titanium-niobium alloys, and to compare them with the behavior of such type of cells on commercial pure titanium. Samples prepared using powder metallurgy were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and metallographic and profilometer analyses. Osteogenic cells from newborn rat calvaria were plated over different groups: dense or porous samples composed of Ti or Ti-35niobium (Nb). Cell adhesion, cell proliferation, MTT assay, cell morphology, protein total content, alkaline phosphatase activity, and mineralization nodules were assessed. Results from XRD and EDS analysis confirmed the presence of Ti and Nb in the test alloy. Metallographic analysis revealed interconnected pores, with pore size ranging from 138 to 150μm. The profilometer analysis detected the greatest rugosity within the dense alloy samples. In vitro tests revealed similar biocompatibility between Ti-35Nb and Ti; furthermore, it was possible to verify that the association of porous surface topography and the Ti-35Nb alloy positively influenced mineralized matrix formation. We propose that the Ti-35Nb alloy with porous topography constitutes a biocompatible material with great potential for use in biomedical implants. Copyright © 2015 Elsevier B.V. All rights reserved.

Solvothermal synthesis of platinum alloy nanoparticles for oxygen reduction electrocatalysis.

PubMed

Carpenter, Michael K; Moylan, Thomas E; Kukreja, Ratandeep Singh; Atwan, Mohammed H; Tessema, Misle M

2012-05-23

Platinum alloy nanoparticles show great promise as electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes. We report here on the use of N,N-dimethylformamide (DMF) as both solvent and reductant in the solvothermal synthesis of Pt alloy nanoparticles (NPs), with a particular focus on Pt-Ni alloys. Well-faceted alloy nanocrystals were generated with this method, including predominantly cubic and cuboctahedral nanocrystals of Pt(3)Ni, and octahedral and truncated octahedral nanocrystals of PtNi. X-ray diffraction (XRD) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), coupled with energy dispersive spectroscopy (EDS), were used to characterize crystallite morphology and composition. ORR activities of the alloy nanoparticles were measured with a rotating disk electrode (RDE) technique. While some Pt(3)Ni alloy nanoparticle catalysts showed specific activities greater than 1000 μA/cm(2)(Pt), alloy catalysts prepared with a nominal composition of PtNi displayed activities close to 3000 μA/cm(2)(Pt), or almost 15 times that of a state-of-the-art Pt/carbon catalyst. XRD and EDS confirmed the presence of two NP compositions in this catalyst. HAADF-STEM examination of the PtNi nanoparticle catalyst after RDE testing revealed the development of hollows in a number of the nanoparticles due to nickel dissolution. Continued voltage cycling caused further nickel dissolution and void formation, but significant activity remained even after 20,000 cycles.

Synthesis and influence of ultrasonic treatment on luminescence of Mn incorporated ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Cadis, A.-I.; Muresan, L. E.; Perhaita, I.; Munteanu, V.; Karabulut, Y.; Garcia Guinea, J.; Canimoglu, A.; Ayvacikli, M.; Can, N.

2017-10-01

Manganese (Mn) doping of ZnS phosphors was achieved by precipitation method using different ultrasound (US) maturation times. The structural and luminescence properties of the samples were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL), and cathodoluminescence (CL). The real amount of manganese incorporated in ZnS lattice was calculated based on ICP-OES results. According with XRD patterns, the phase structure of ZnS:Mn samples is cubic. EDS spectra reveal deviations of the Mn dopant concentration from the target composition. Both 300 K PL and CL emission spectra of the Mn doped ZnS phosphors display intense orange emission at 590 and 600 nm, respectively, which is characteristic emission of Mn ion corresponding to a 4T1→6A1 transition. Both PL and CL spectra confirmed manganese is substitutionally incorporated into the ZnS host as Mn2+. However, it is suggested that the origin of broad blue emission around 400 nm appeared in CL is due to the radiative recombination at deep level defect states in the ZnS. The ultrasound treatment at first enhances the luminescent intensity by ∼3 times in comparison with samples prepared by classical way. This study gives rise to an optimization guideline, which is extremely demanded for the development of new luminescent materials.

Exploring coherent electron excitation and migration dynamics by electron diffraction with ultrashort X-ray pulses.

PubMed

Yuan, Kai-Jun; Bandrauk, André D

2017-10-04

Exploring ultrafast charge migration is of great importance in biological and chemical reactions. We present a scheme to monitor attosecond charge migration in molecules by electron diffraction with spatial and temporal resolutions from ab initio numerical simulations. An ultraviolet pulse creates a coherent superposition of electronic states, after which a time-delayed attosecond X-ray pulse is used to ionize the molecule. It is found that diffraction patterns in the X-ray photoelectron spectra show an asymmetric structure, which is dependent on the time delay between the pump-probe pulses, encoding the information of molecular orbital symmetry and chemical bonding. We describe these phenomena by developing an electronic time-dependent ultrafast molecular photoionization model of a coherent superposition state. The periodical distortion of electron diffraction patterns illustrates the evolution of the electronic coherence, providing a tool for attosecond imaging of ultrafast molecular reaction processes.

Electron coherent diffraction tomography of a nanocrystal

NASA Astrophysics Data System (ADS)

Dronyak, Roman; Liang, Keng S.; Tsai, Jin-Sheng; Stetsko, Yuri P.; Lee, Ting-Kuo; Chen, Fu-Rong

2010-05-01

Coherent diffractive imaging (CDI) with electron or x-ray sources is a promising technique for investigating the structure of nanoparticles down to the atomic scale. In electron CDI, a two-dimensional reconstruction is demonstrated using highly coherent illumination from a field-emission gun as a source of electrons. In a three-dimensional (3D) electron CDI, we experimentally determine the morphology of a single MgO nanocrystal using the Bragg diffraction geometry. An iterative algorithm is applied to invert the 3D diffraction pattern about a (200) reflection of the nanoparticle measured at an angular range of 1.8°. The results reveal a 3D image of the sample at ˜8 nm resolution, and agree with a simulation. Our work demonstrates an alternative approach to obtain the 3D structure of nanocrystals with an electron microscope.

Suppressing Ghost Diffraction in E-Beam-Written Gratings

NASA Technical Reports Server (NTRS)

Wilson, Daniel; Backlund, Johan

2009-01-01

A modified scheme for electron-beam (E-beam) writing used in the fabrication of convex or concave diffraction gratings makes it possible to suppress the ghost diffraction heretofore exhibited by such gratings. Ghost diffraction is a spurious component of diffraction caused by a spurious component of grating periodicity as described below. The ghost diffraction orders appear between the main diffraction orders and are typically more intense than is the diffuse scattering from the grating. At such high intensity, ghost diffraction is the dominant source of degradation of grating performance. The pattern of a convex or concave grating is established by electron-beam writing in a resist material coating a substrate that has the desired convex or concave shape. Unfortunately, as a result of the characteristics of electrostatic deflectors used to control the electron beam, it is possible to expose only a small field - typically between 0.5 and 1.0 mm wide - at a given fixed position of the electron gun relative to the substrate. To make a grating larger than the field size, it is necessary to move the substrate to make it possible to write fields centered at different positions, so that the larger area is synthesized by "stitching" the exposed fields.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashida, Misa; Malac, Marek; Egerton, Ray F.

Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy ofmore » the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.« less

Synthesis of SiO(x) powder using DC arc plasma.

PubMed

Jung, Chan-Ok; Park, Dong-Wha

2013-02-01

SiO(x) was prepared by DC arc plasma and applied to the anode material of lithium ion batteries. A pellet of a mixture of Si and SiO2 was used as the raw material. The ratios of the silicon and silicon dioxide (SiO2) mixtures were varied by controlling the Si-SiO2 molar ratio (Si-SiO2 = 1-4). Hydrogen gas was used as the reduction atmosphere in the chamber. The prepared SiO(x) was collected on the chamber wall. The obtained SiO(x) was characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and TEM showed that the phase composition of the prepared particles was composed of amorphous SiO(x) and crystalline Si. The prepared SiO(x) showed wire and spherical morphology. XPS indicated the bonding state and 'x' value of the prepared SiO(x), which was close to one. The result of prepared SiO(x) is discussed from thermodynamic equilibrium calculations. The electrochemical behavior of the silicon monoxide anode was investigated.

Synthesis of CdS/ZnO/graphene composite with high-efficiency photoelectrochemical activities under solar radiation

NASA Astrophysics Data System (ADS)

Han, Weijia; Ren, Long; Qi, Xiang; Liu, Yundan; Wei, Xiaolin; Huang, Zongyu; Zhong, Jianxin

2014-04-01

A novel ternary CdS/ZnO/graphene composite has been successfully prepared by loading ZnO and CdS nanoparticles in graphene nanosheets via a facile one-step hydrothermal method. The microstructures and properties have been examined by X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive spectroscope (EDS), transmission electron microscopy, Raman and UV-vis diffuse reflectance spectra (DRS). The characterization results reveal that the crystalline of the composite is very well, the graphene sheets were tightly coated with ZnO and CdS nanoparticles, and the light-harvesting was effectively strengthened. Taking photoelectrochemical test, the ternary CdS/ZnO/graphene composite exhibits enhanced photocatalytic activity compared with its foundation matrix binary composites and pure ZnO and CdS. The improved photocatalytic performance can be attributed to the enhanced light absorption, the extremely efficient charge separation, as well as superior durability of the ternary composite. It is proposed that graphene-based composites by coupling graphene to suitable, multiple semiconductors can not only greatly improve the capacity for photocatalytic, but also expand the exploration and utilization of graphene-based nanocomposites for energy conversion.

Highly hydrophilic poly(vinylidene fluoride)/meso-titania hybrid mesoporous membrane for photocatalytic membrane reactor in water

NASA Astrophysics Data System (ADS)

Wang, Meng; Yang, Guang; Jin, Peng; Tang, Hao; Wang, Huanhuan; Chen, Yong

2016-01-01

The high hydrophobicity of poly(vinylidene fluoride) (PVDF) membrane remains an obstacle to be applied in some purification processes of water or wastewater. Herein, a highly hydrophilic hybrid mesoporous titania membrane composed of mesoporous anatase titania (meso-TiO2) materials inside the three-dimensional (3D) macropores of PVDF membrane was successfully prepared by using the dual-templated synthesis method combined with solvent extraction and applied as the photocatalytic membrane reactor for the photodegredation of organic dye in water. The structure and the properties of as-prepared hybrid membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption-desorption and contact angle measurements. It was found that the hydrophilicity of PVDF membrane can be significantly improved by filling mesoporous TiO2 inside the 3D macropores of PVDF membrane. Moreover, such a PVDF/meso-TiO2 hybrid membrane exhibits promising photocatalytic degradation of dye in water due to the existence of mesoporous anatase TiO2 materials inside PVDF membrane. This study provides a new strategy to simultaneously introduce hydrophilicity and some desirable properties into PVDF and other hydrophobic membranes.

Removal of copper and nickel from water using nanocomposite of magnetic hydroxyapatite nanorods

NASA Astrophysics Data System (ADS)

Thanh, Dong Nguyen; Novák, Pavel; Vejpravova, Jana; Vu, Hong Nguyen; Lederer, Jaromír; Munshi, Tasnim

2018-06-01

A nanocomposite of magnetic hydroxyapatite was synthesized and tested as an adsorbent for the removal of copper (Cu (II)) and nickel (Ni(II)) from aqueous solution. The adsorbent was investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy equipped with an Energy Dispersive Spectrometer (SEM/EDS), X-ray powder diffraction (XRD) and the Brunauer-Elmet-Teller nitrogen adsorption technique (BET-N2 adsorption). Batch experiments were carried out to determine and compare the adsorption parameters of Fe3O4 and its composite with hydroxyapatite. It was found that the adsorbent is nanostructured and has a specific surface area of 101.2 m2 g-1. The Langmuir adsorption isotherm was found to be an appropriate model to describe the adsorption processes, showing the adsorption capacities of Cu(II) and Ni(II) of 48.78 mg g-1 and 29.07 mg g-1, respectively. In addition to the high adsorption capacity, the fully-adsorbed material could be easily separated from aqueous media using an external magnetic field. These results suggested that the utilization of new hydroxyapatite - Fe3O4 nanocomposite for the removal of Cu(II) and Ni(II) is a promising method in water technology.

Structure, Microsegregation, and Precipitates of an Alloy 690 ESR Ingot in Industrial Scale

NASA Astrophysics Data System (ADS)

Wang, Min; Zha, Xiangdong; Gao, Ming; Ma, Yingche; Liu, Kui; Li, Yiyi

2015-11-01

The structure, interdendritic, and intergranular segregation, and precipitates of an Alloy 690 electro-slag remelting (ESR) ingot in commercial scale (3t) were investigated by the optical microscopy, electroprobe microanalysis, scanning electron microscopy, and transmission electron microscopy (TEM) techniques. The results indicate that the central longitudinal section of the ESR ingot comprised the ramp-up, steady-state, and hot-top regions, which could be easily distinguished from each other through the macrostructures of them. In the interdendritic area, Cr and Ti were enriched, while Ni and Fe were depleted, and the nominal segregation indexes ( ζ i = C 0 i / C interdendritic i ) of Ti, Cr, and Ni were 0.40, 0.91, and 1.04, respectively, in the hot-top region where suffered the severest segregation. Nitrides, principally precipitated between dendrites, were identified as TiN by TEM and EDS. The morphology, size distribution, and volume fraction of them were determined as well. In terms of the intergranular area, Cr and C coexisted, while Ni and Fe were depleted. And the dendrite-like carbides continuously distributed on the interface between grains, which were identified as M23C6 by the selected area diffraction pattern.

Stability of Catalyzed Magnesium Hydride Nanocrystalline During Hydrogen Cycling. Part II: Microstructure Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Chengshang; Fang, Zhigang Zak; Bowman, Robert C.

2015-10-01

In Part I, the cyclic stabilities of the kinetics of catalyzed MgH2 systems including MgH2–TiH2, MgH2–TiMn2, and MgH2–VTiCr were investigated, showing stable kinetics at 300 °C but deteriorations of the hydrogenation kinetics at temperatures below 150 °C. The present Part II describes the characterization of uncycled and cycled catalyzed MgH2 by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. XRD analysis shows the crystallite sizes of the Mg and MgH2 significantly increased after the cycling. The mean crystallite sizes of the catalysts (TiH2 and VTiCr) increased moderately after the cycling. SEMmore » and TEM imaging were used to compare the microstructures of uncycled (as-milled) and cycled materials, revealing a drastic change of the microstructure after 100 cycles. In particular, results from energy-dispersive spectroscopy (EDS) mapping show that a change of distribution of the catalyst particles in the Mg and MgH2 phase occurred during the cycling.« less

Synthesis of SiCN@TiO2 core-shell ceramic microspheres via PDCs method

NASA Astrophysics Data System (ADS)

Liu, Hongli; Wei, Ning; Li, Jing; Zhang, Haiyuan; Chu, Peng

2018-02-01

A facile and effective polymer-derived ceramics (PDCs) emulsification-crosslinking-pyrolysis method was developed to fabricate SiCN@TiO2 core-shell ceramic microspheres with polyvinylsilazane (PVSZ) and tetrabutyl titanate (TBT) as precursors. The TBT: PVSZ mass ratios, emulsifier concentrations and the pyrolysis temperature were examined as control parameters to tune the size and morphology of microspheres. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the synthesized SiCN@TiO2 microspheres to be comprised of SiCN core coated with TiO2 crystals, with an average size of 0.88 μm when pyrolyzed at 1400 °C. The analysis of Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) ensured that SiCN@TiO2 core-shell ceramic microspheres composed of rutile TiO2, β-SiC and Si3N4 crystalline phases, The thermal properties were characterized by thermogravimetric analysis (TGA). The obtained SiCN@TiO2 core-shell ceramic microspheres were the promising candidate of the infrared opacifier in silica aerogels and this technique can be extended to other preceramic polymers.

Synthesis of a novel glucose capped gold nanoparticle as a better theranostic candidate

PubMed Central

Suvarna, Saritha; Das, Ujjal; KC, Sunil; Mishra, Snehasis; Sudarshan, Mathummal; Saha, Krishna Das; Dey, Sanjit; Chakraborty, Anindita; Narayana, Y.

2017-01-01

Gold nanoparticles are predominantly used in diagnostics, therapeutics and biomedical applications. The present study has been designed to synthesize differently capped gold nanoparticles (AuNps) by a simple, one-step, room temperature procedure and to evaluate the potential of these AuNps for biomedical applications. The AuNps are capped with glucose, 2-deoxy-D-glucose (2DG) and citrate using different reducing agents. This is the first report of synthesis of 2DG-AuNp by the simple room temperature method. The synthesized gold nanoparticles are characterized with UV-Visible Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED), Dynamic light scattering (DLS), and Energy-dispersive X-ray spectroscopy (SEM-EDS). Surface-enhanced Raman scattering (SERS) study of the synthesized AuNps shows increase in Raman signals up to 50 times using 2DG. 3-(4, 5-dimethylthiozol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay has been performed using all the three differently capped AuNps in different cell lines to assess cytotoxcity if any, of the nanoparticles. The study shows that 2DG-AuNps is a better candidate for theranostic application. PMID:28582426

Template-Free Hydrothermal Synthesis, Mechanism, and Photocatalytic Properties of Core-Shell CeO2 Nanospheres

NASA Astrophysics Data System (ADS)

Li, Huijie; Meng, Fanming; Gong, Jinfeng; Fan, Zhenghua; Qin, Rui

2018-03-01

CeO2 nanospheres with the core-shell nanostructure have been successfully synthesized by a template-free hydrothermal method. The structures, morphologies and optical properties of core-shell CeO2 nanospheres were analyzed by X-ray diffraction (XRD), TG, Fourier transform infrared spectroscopy, XRD, EDS, SAED, scanning electron microscopy and transmission electron microscopy, UV-Vis diffuse reflectance spectra, Raman analyses. The degradation efficiencies of core-shell CeO2 nanospheres for methyl orange were as high as 93.49, 95.67 and 98.28% within 160 min, and the rates of photo degradation of methyl orange by core-shell CeO2 nanospheres under UV-light were 0.01693, 0.01782 and 0.02375 min-1. Methyl orange was degraded in photocatalytic oxidation processes, which mainly gave the credit to a large number of reactive species including h+, surface superoxide species ·O2 -, and ·OH radicals. The core-shell structure, small crystallite size and the conversion between Ce3+ and Ce4+ of CeO2 nanospheres were of importance for its catalytic activity. These results demonstrated the possibility of improving the efficient catalysts of the earth abundant CeO2 catalysts.

Analysis of Roman age wall paintings found in Pordenone, Trieste and Montegrotto.

PubMed

Mazzocchin, G A; Agnoli, F; Salvadori, M

2004-10-20

The aim of the present work is the study of many fragments of wall painting from archaeological excavations in three different Roman age sites dating back to the I Century before Common Era: Pordenone (località Torre); Trieste (Crosada) and Padova (Montegrotto). The techniques used were optical microscopy, scanning electron microscopy (SEM), equipped with a EDS microanalysis detector, X-rays powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Fourier transform Raman spectroscopy (FT-Raman) and electron paramagnetic resonance (EPR) spectroscopy. The identified pigments were: cinnabar, hematite, celadonite, glauconite, cuprorivaite (Egyptian blue), yellow and red ochre, calcite, limonite, coal black. In general, the mortar preparation did not correspond to the complex procedure suggested by Vitruvius (De Architectura), but generally showed a porous layer, with crushed grains under the pigment layer. In some cases, two superimposed pigment layers were found: yellow superimposed on both red and pink, black on pink, green on black. The slight differences we found in the use of the pigments in the three studied sites might show that the same technology, culture and taste spread all over the Roman Empire in North Eastern Italy (X(a) Regio Venetia et Histria).

Novel synthesis and characterization of pristine Cu nanoparticles for the non-enzymatic glucose biosensor.

PubMed

Dayakar, T; Rao, K Venkateswara; Bikshalu, K; Rajendar, V; Park, Si-Hyun

2017-07-01

Non enzymatic electrochemical glucose sensing was developed based on pristine Cu Nanopartilces (NPs)/Glassy Carbon Electrode (GCE) which can be accomplished by simple green method via ocimum tenuiflorum leaf extract. Then, the affect of leaf extract addition on improving Structural, Optical and electrochemical properties of pristine cu NPs was investigated. The synthesized Cu NPs were characterized with X-ray diffraction (X-ray), Uv-Visible spectroscopy (Uv-Vis), Fourier transformation infrared spectroscopy (FTIR), Particle size distribution (PSA), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) for structural optical and morphological studies respectively. The synthesized Cu NPs were coated over glassy carbon electrode (GCE) to study the electrochemical response of glucose by cyclic voltammetry and ampherometer. The results indicates that the modified biosensor shows a remarkable sensitivity (1065.21 μA mM -1  cm -2 ), rapid response time (<3s), wide linear range (1 to 7.2 mM), low detection limit (0.038 μM at S/N = 3). Therefore, the prepared Cu NPs by the Novel Bio-mediated route were exploited to construct a non-enzymatic glucose biosensor for sustainable clinical field applications.

High-strength bioresorbable Fe–Ag nanocomposite scaffolds: Processing and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharipova, Aliya; Skolkovo Institute of Science and Technology, Skolkovo, 143025; Psakhie, Sergey G.

2015-10-27

High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na{sub 2}SO{sub 4} and K{sub 2}CO{sub 3} salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy’s law. Scaffolds with 50%more » and 55% porosity exhibited high compressive strength (18–22 MPa), compressive strength of 8–12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6{sup −6} cm{sup 2}) is close to the range of trabecular bone.« less

Effect of magnesium content on the microstructure and dry sliding wear behavior of centrifugally cast functionally graded A356-Mg2Si in situ composites

NASA Astrophysics Data System (ADS)

Ram, Subhash Chandra; Chattopadhyay, K.; Chakrabarty, I.

2018-04-01

Functionally graded A356 alloy (Al–7.2Si–0.3Mg) –Mg2Si in situ composites have been synthesized via centrifugal casting route. Mg2Si particles tend to migrate towards the core of the tubular product by centrifugal force. The in situ formed Mg2Si particles in composites are characterized by x-ray diffraction (XRD) analysis, Energy dispersive spectrometry (EDS), Optical, Scanning Electron and Transmission Electron Microscopy. Apart from primary blocky Mg2Si particles the matrix contains other phases viz. Al-Si eutectic, pseudo-binary Al-Mg2Si eutectic and Al-Fe-Si intermetallics. Density is found to decrease and %porosity is increased with increase in volume fraction of Mg2Si. Maximum hardness was observed at the inner core region due to maximum segregation of Mg2Si particles and gradually decreases towards the outer periphery region. The dry sliding wear was evaluated with varying parameters such as normal loads (N) and sliding distances (m). A substantial increase in wear resistance at the inner core region is observed. From the worn surface characterization, the wear mechanisms have been explained.

Liquefied petroleum gas sensor based on manganese (III) oxide and zinc manganese (III) oxide nanoparticles

NASA Astrophysics Data System (ADS)

Sharma, Shiva; Chauhan, Pratima; Husain, Shahid

2018-01-01

In this paper, {{{Mn}}}2{{{O}}}3 and {{{ZnMn}}}2{{{O}}}4 nanoparticles (NPs) are successfully synthesized using chemical co-precipitation method at room temperature and further annealed at 450 °C. The structure, crystallite size, morphology, specific surface area (SSA) and band gap energy have been determined by x-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy (SEM-EDS) and UV-visible spectrophotometer. The sensor films of the {{{Mn}}}2{{{O}}}3 NPs and {{{ZnMn}}}2{{{O}}}4 NPs have been fabricated onto glass substrate using spin coater system separately. These sensor films are investigated for different concentrations (200-1200 ppm) of liquefied petroleum gas (LPG) at different operating temperatures ranging from 100 °C to 400 °C. A comparative study of gas sensing properties shows that spinel {{{ZnMn}}}2{{{O}}}4 sensor film exhibit excellent response (≈ 80 % ) towards 1000 ppm LPG at 300 °C in comparison to {{{Mn}}}2{{{O}}}3 sensor films. The enhancement in the gas sensing characteristics of {{{ZnMn}}}2{{{O}}}4 sensor film is attributed to the reduced crystallite size, greater SSA, and modification in structure as well as morphology.

Photocatalytic detoxification of Acid Red 18 by modified ZnO catalyst under sunlight irradiation

NASA Astrophysics Data System (ADS)

Senthilraja, A.; Subash, B.; Dhatshanamurthi, P.; Swaminathan, M.; Shanthi, M.

2015-03-01

In this work, hybrid structured Bi-Au-ZnO composite was prepared by precipitation-decomposition method. This method is mild, economical and efficient. Bi-Au-ZnO was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectrum (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL) and BET surface area measurements. Photocatalytic activity of Bi-Au-ZnO was evaluated by irradiating the Acid Red 18 (AR 18) dye solution under sun light. Heterostructured Bi-Au-ZnO photocatalyst showed higher photocatalytic activity than those of individual Bi-ZnO, Au-ZnO, bare ZnO, and TiO2-P25 at pH 11. The effects of operational parameters such as the amount of catalyst dosage, dye concentration, initial pH on photo mineralization of AR 18 dye have been analyzed. The mineralization of AR 18 has been confirmed by chemical oxygen demand (COD) measurements. A possible mechanism is proposed for the degradation of AR 18 under sun light. Finally, Bi-Au-ZnO heterojunction photocatalyst was more stable and could be easily recycled several times opening a new avenue for potential industrial applications.

The impact of electronic health records on care of heart failure patients in the emergency room

PubMed Central

Park, Young-Taek; Du, Jing; Theera-Ampornpunt, Nawanan; Gordon, Bradley D; Bershow, Barry A; Gensinger, Raymond A; Shrift, Michael; Routhe, Daniel T; Speedie, Stuart M

2011-01-01

Objective To evaluate if electronic health records (EHR) have observable effects on care outcomes, we examined quality and efficiency measures for patients presenting to emergency departments (ED). Materials and methods We conducted a retrospective study of 5166 adults with heart failure in three metropolitan EDs. Patients were termed internal if prior information was in the EHR upon ED presentation, otherwise external. Associations of internality with hospitalization, mortality, length of stay (LOS), and numbers of tests, procedures, and medications ordered in the ED were examined after adjusting for age, gender, race, marital status, comorbidities and hospitalization as a proxy for acuity level where appropriate. Results At two EDs internals had lower odds of mortality if hospitalized (OR 0.55; 95% CI 0.38 to 0.81 and 0.45; 0.21 to 0.96), fewer laboratory tests during the ED visit (−4.6%; −8.9% to −0.1% and −14.0%; −19.5% to −8.1%) as well as fewer medications (−33.6%; −38.4% to −28.4% and −21.3%; −33.2% to −7.3%). At one of these two EDs, internals had lower odds of hospitalization (0.37; 0.22 to 0.60). At the third ED, internal patients only experienced a prolonged ED LOS (32.3%; 6.3% to 64.8%) but no other differences. There was no association with hospital LOS or number of procedures ordered. Discussion EHR availability was associated with salutary outcomes in two of three ED settings and prolongation of ED LOS at a third, but evidence was mixed and causality remains to be determined. Conclusions An EHR may have the potential to be a valuable adjunct in the care of heart failure patients. PMID:22071528

Dynamic diffraction effects and coherent breathing oscillations in ultrafast electron diffraction in layered 1T-TaSeTe

PubMed Central

Wei, Linlin; Sun, Shuaishuai; Guo, Cong; Li, Zhongwen; Sun, Kai; Liu, Yu; Lu, Wenjian; Sun, Yuping; Tian, Huanfang; Yang, Huaixin; Li, Jianqi

2017-01-01

Anisotropic lattice movements due to the difference between intralayer and interlayer bonding are observed in the layered transition-metal dichalcogenide 1T-TaSeTe following femtosecond laser pulse excitation. Our ultrafast electron diffraction investigations using 4D-transmission electron microscopy (4D-TEM) clearly reveal that the intensity of Bragg reflection spots often changes remarkably due to the dynamic diffraction effects and anisotropic lattice movement. Importantly, the temporal diffracted intensity from a specific crystallographic plane depends on the deviation parameter s, which is commonly used in the theoretical study of diffraction intensity. Herein, we report on lattice thermalization and structural oscillations in layered 1T-TaSeTe, analyzed by dynamic diffraction theory. Ultrafast alterations of satellite spots arising from the charge density wave in the present system are also briefly discussed. PMID:28470025

Coherent diffraction imaging analysis of shape-controlled nanoparticles with focused hard X-ray free-electron laser pulses.

PubMed

Takahashi, Yukio; Suzuki, Akihiro; Zettsu, Nobuyuki; Oroguchi, Tomotaka; Takayama, Yuki; Sekiguchi, Yuki; Kobayashi, Amane; Yamamoto, Masaki; Nakasako, Masayoshi

2013-01-01

We report the first demonstration of the coherent diffraction imaging analysis of nanoparticles using focused hard X-ray free-electron laser pulses, allowing us to analyze the size distribution of particles as well as the electron density projection of individual particles. We measured 1000 single-shot coherent X-ray diffraction patterns of shape-controlled Ag nanocubes and Au/Ag nanoboxes and estimated the edge length from the speckle size of the coherent diffraction patterns. We then reconstructed the two-dimensional electron density projection with sub-10 nm resolution from selected coherent diffraction patterns. This method enables the simultaneous analysis of the size distribution of synthesized nanoparticles and the structures of particles at nanoscale resolution to address correlations between individual structures of components and the statistical properties in heterogeneous systems such as nanoparticles and cells.

Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

NASA Astrophysics Data System (ADS)

He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

2013-10-01

Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector.

PubMed

Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Bender, H A; Wilcox, N S

2010-01-01

Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

Structural and Functional Analyses of the Six1 Transcriptional Complex for Anti-Breast Cancer Drug Design

DTIC Science & Technology

2011-04-01

of structurally highly related initial hits. 
 Fig. 8. A malachite green based secondary assay confirmed the top two initial hits do inhibit ED’s...Crystals (left) and diffraction pattern (right) of ED. using a malachite -green based phosphatase assay (Fig. 8). We further demonstrated that these

Crystallographic Study of Itokawa Particle, RA-QD02-0127 by Using Energy-Scanning X-Ray Diffraction Method with Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Hagiya, K.; Ohsumi, K.; Komatsu, M.; Mikouchi, T.; Zolensky, M. E.; Hirata, A.; Yamaguchi, S.; Kurokawa, A.

2016-01-01

The petrographic study of Itokawa particle, RA-QD02-0127 has been performed by SEM-EDS and optical microscope observations. The purpose of this study is to understand better the metamorphic and impact shock history of asteroid Itokawa, and other S-class asteroids.

Photometric study of single-shot energy-dispersive x-ray diffraction at a laser plasma facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoidn, O. R.; Seidler, G. T., E-mail: seidler@uw.edu

The low repetition rates and possible shot-to-shot variations in laser-plasma studies place a high value on single-shot diagnostics. For example, white-beam scattering methods based on broadband backlighter x-ray sources are used to determine changes in the structure of laser-shocked crystalline materials by the evolution of coincidences of reciprocal lattice vectors and kinematically allowed momentum transfers. Here, we demonstrate that white-beam techniques can be extended to strongly disordered dense plasma and warm dense matter systems where reciprocal space is only weakly structured and spectroscopic detection is consequently needed to determine the static structure factor and thus, the ion-ion radial distribution function.more » Specifically, we report a photometric study of energy-dispersive x-ray diffraction (ED-XRD) for structural measurement of high energy density systems at large-scale laser facilities such as OMEGA and the National Ignition Facility. We find that structural information can be obtained in single-shot ED-XRD experiments using established backlighter and spectrometer technologies.« less

Synthesis of Fe-based core@ZnO shell nanopowders by laser pyrolysis for biomedical applications

NASA Astrophysics Data System (ADS)

Gavrila-Florescu, Lavinia; Dumitrache, Florian; Balas, Mihaela; Fleaca, Claudiu Teodor; Scarisoreanu, Monica; Morjan, Iuliana P.; Dutu, Elena; Ilie, Alina; Banici, Ana-Maria; Locovei, Claudiu; Prodan, Gabriel

2017-12-01

Nano-sized Fe-based (metallic, carbidic and/or oxidic) core@ZnO shell particles have been successfully synthesized in one step by the laser-induced pyrolysis method in an oxygen-deficient environment. The specific precursors were separately introduced through a three concentric nozzles injector: Fe(CO)5 vapors carried by C2H4 sensitizer (central flow), Zn(C2H5)2 vapors carried and diluted with Ar (middle annular coflow) and Ar containing low amount of O2 (external flow). Keeping constant the ethylene-carried Fe(CO)5 and O2 flows, while diminishing the Zn(C2H5)2 flow, we observed an increase of the Fe/Zn ratio in the resulted nanopowders. Also, using the same metal precursor flows, a nonlinear correlation between O2 external flow and nanocomposite atomic oxygen content is evidenced, indicating a possible interference of supplementary oxidation after air exposure. However, the lowest oxygen content along with metallic zinc was found in the sample synthesized in the most oxygen-deficient environment. Transmission electron microscopy (TEM), high-resolution electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS) and magnetic analyses were performed for a comprehensive characterization. The aqueous Fe-based@ZnO nanoparticles (NPs) suspensions were prepared using L-Dopa ( l-3,4-dihydroxy-phenylalanine) as stabilizing agent in physiologic media. Also, a biocompatibility in vitro study was performed for PBS (phosphate buffered saline)-dispersed L-Dopa-stabilized Fe-based@ZnO nanoparticles with the best core-shell structural features on both human normal lung fibroblasts and tumoral colorectal cells. Our results proved the ability of these newly synthesized nanostructures to target cancer cells in order to induce cytotoxicity and to exhibit biocompatibility on normal cells for maintaining the proper function of healthy tissue.

Hydrothermal synthesis of highly crystalline RuS{sub 2} nanoparticles as cathodic catalysts in the methanol fuel cell and hydrochloric acid electrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yanjuan; College of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, 2699 Qianjin Street, Changchun 130012; Li, Nan, E-mail: lin@jlu.edu.cn

2015-05-15

Highlights: • Highly crystalline RuS{sub 2} nanoparticles have been first synthesized by a “one-step” hydrothermal method. • The product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} with average particle size of 14.8 nm. • RuS{sub 2} nanoparticles were used as cathodic catalysts in methanol fuel cell and hydrochloric acid electrolysis. • The catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}. - Abstract: Highly crystalline ruthenium sulfide (RuS{sub 2}) nanoparticles have been first synthesized by a “one-step” hydrothermal method at 400 °C, using ruthenium chloride and thiourea as reactants. The products were characterized bymore » powder X-ray diffraction (XRD), scanning electron microscopy/energy disperse spectroscopy (SEM/EDS), thermo gravimetric-differential thermal analyze (TG-DTA), transmission electron microscopy equipped with selected area electron diffraction (TEM/SAED). Fourier transform infrared spectra (IR), and X-ray photoelectron spectroscopy (XPS). XRD result illustrates that the highly crystalline product presents a pure cubic phase of stoichiometric ratio RuS{sub 2} and the average particle size is 14.8 nm. SEM and TEM images display the products have irregular shape of 6–25 nm. XPS analyst indicates that the sulfur exists in the form of S{sub 2}{sup 2−}. Cyclic voltammetry (CV), rotating disk electrode (RDE), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) measurements are conducted to evaluate the electrocatalytic activity and stability of the highly crystalline RuS{sub 2} nanoparticles in oxygen reduction reaction (ORR) for methanol fuel cell and hydrochloric acid electrolysis. The results illustrate that RuS{sub 2} is active towards oxygen reduction reaction. Although the activity of RuS{sub 2} is lower than that of Pt/C, the RuS{sub 2} catalyst outperforms commercial Pt/C in methanol tolerance and stability towards Cl{sup −}.« less

Microstructure and hot corrosion behavior of the Ni-based superalloy GH202 treated by laser shock processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Jiangdong

The effects of laser shock processing on microstructure, the residual stress, and hot corrosion behavior of the Ni-based superalloy GH202 were investigated. The microstructures of GH202 before and after laser shock processing (LSP) were characterized by electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). A large number of crystal defects (twins, dislocation arrays, and high dense tangles) were generated on the surface of GH202 treated with LSP. The cross-sectional compressive residual stress and micro-hardness of specimens treated by LSP were improved significantly. The corrosion kinetics of GH202 with or without LSP treatment at 800 °C and 900 °C weremore » investigated. Analysis by X-ray diffraction (XRD) revealed that the corrosion products mainly consist of Cr{sub 2}O{sub 3}, TiO{sub 2}, Al{sub 2}O{sub 3}, NiO, CrS, Ni{sub 3}S{sub 2}, and Na{sub 2}CrO{sub 4}. The surface and cross-section morphologies were observed by scanning electron microscope (SEM) combined with energy dispersive spectroscopy (EDS). The results confirmed that the crystal defects induced by LSP promotes the creation of diffusion paths for elements (Cr, Al, and Ti), allowing the formation of tiny homogeneous oxidation films in a very short time. Additionally, the spallation of oxidation film on the treated specimens was alleviated significantly. Overall, the hot corrosion resistance of Ni-based GH202 induced by LSP was improved in Na{sub 2}SO{sub 4} and NaCl molten salt from 800 °C to 900 °C. - Highlights: • Microstructure changes of GH202 before and after LSP were observed by EBSD and TEM. • The hardness and residual compressive stress after LSP were significantly increased. • The increased diffusion paths for elements helped to form oxidation films quickly. • Hot corrosion resistance of GH202 after LSP was significantly improved.« less

Estimates of electronic medical records in U.S. Emergency departments.

PubMed

Geisler, Benjamin P; Schuur, Jeremiah D; Pallin, Daniel J

2010-02-17

Policymakers advocate universal electronic medical records (EMRs) and propose incentives for "meaningful use" of EMRs. Though emergency departments (EDs) are particularly sensitive to the benefits and unintended consequences of EMR adoption, surveillance has been limited. We analyze data from a nationally representative sample of US EDs to ascertain the adoption of various EMR functionalities. We analyzed data from the National Hospital Ambulatory Medical Care Survey, after pooling data from 2005 and 2006, reporting proportions with 95% confidence intervals (95% CI). In addition to reporting adoption of various EMR functionalities, we used logistic regression to ascertain patient and hospital characteristics predicting "meaningful use," defined as a "basic" system (managing demographic information, computerized provider order entry, and lab and imaging results). We found that 46% (95% CI 39-53%) of US EDs reported having adopted EMRs. Computerized provider order entry was present in 21% (95% CI 16-27%), and only 15% (95% CI 10-20%) had warnings for drug interactions or contraindications. The "basic" definition of "meaningful use" was met by 17% (95% CI 13-21%) of EDs. Rural EDs were substantially less likely to have a "basic" EMR system than urban EDs (odds ratio 0.19, 95% CI 0.06-0.57, p = 0.003), and Midwestern (odds ratio 0.37, 95% CI 0.16-0.84, p = 0.018) and Southern (odds ratio 0.47, 95% CI 0.26-0.84, p = 0.011) EDs were substantially less likely than Northeastern EDs to have a "basic" system. EMRs are becoming more prevalent in US EDs, though only a minority use EMRs in a "meaningful" way, no matter how "meaningful" is defined. Rural EDs are less likely to have an EMR than metropolitan EDs, and Midwestern and Southern EDs are less likely to have an EMR than Northeastern EDs. We discuss the nuances of how to define "meaningful use," and the importance of considering not only adoption, but also full implementation and consequences.

High-resolution scanning precession electron diffraction: Alignment and spatial resolution.

PubMed

Barnard, Jonathan S; Johnstone, Duncan N; Midgley, Paul A

2017-03-01

Methods are presented for aligning the pivot point of a precessing electron probe in the scanning transmission electron microscope (STEM) and for assessing the spatial resolution in scanning precession electron diffraction (SPED) experiments. The alignment procedure is performed entirely in diffraction mode, minimising probe wander within the bright-field (BF) convergent beam electron diffraction (CBED) disk and is used to obtain high spatial resolution SPED maps. Through analysis of the power spectra of virtual bright-field images extracted from the SPED data, the precession-induced blur was measured as a function of precession angle. At low precession angles, SPED spatial resolution was limited by electronic noise in the scan coils; whereas at high precession angles SPED spatial resolution was limited by tilt-induced two-fold astigmatism caused by the positive spherical aberration of the probe-forming lens. Copyright © 2016 Elsevier B.V. All rights reserved.

The Nanocrystalline State of Narrow Gap Semiconducting Chalcogenides

DTIC Science & Technology

2010-08-23

using a 1 nm scanning probe and the EDS microanalysis . For Annealing studies nanocrystal powder samples were placed in ceramic crucibles and annealed...nanocrystals are homogenous single phase EDS spectral images were collected in scanning transmission electron microcopy using a 1 nm electron probe...explorations with alio-valent elements (e.g. Sb3+, Ag+ doping in PbTe). • Perform chemical and physical characterization to demonstrate that nanocrystals are

Analysis of WC/Ni-Based Coatings Deposited by Controlled Short-Circuit MIG Welding

NASA Astrophysics Data System (ADS)

Vespa, P.; Pinard, P. T.; Gauvin, R.; Brochu, M.

2012-06-01

This study investigates the recently developed controlled short-circuit metal inert gas (CSC-MIG) welding system for depositing WC/Ni-based claddings on carbon steel substrates. WC/Ni-based coatings deposited by CSC-MIG were analyzed by optical light microscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) capabilities. X-ray diffraction (XRD) and hardness measurements of depositions are also reported. The CSC-MIG welding system provides a significant amount of user control over the current waveform during welding and has lower heat input when compared with traditional MIG welding. Heat input for the analyzed coatings ranged from 10.1 to 108.7 J/mm. Metallurgically bonded coatings free from spatter and with 0.75% average porosity were produced. It was found that the detrimental decarburization of the WC particles seen in thermal spray systems does not occur when welding with the CSC-MIG. Precipitation of a reaction layer around the reinforcing phase was identified as WC; the average thickness of which increases from 3.8 to 7.2 μm for the low and high heat input condition, respectively. Precipitation of newly formed WC particles was observed; their size distribution increased from D 50 of 2.4 μm in the low heat input weldment to 6.75 μm in the high heat input weldment. The level of dilution of the reinforcing phase increases significantly with heat input. The hardness of the deposited coatings decreases from 587 HV10 to 410 HV10 when the energy input was increased from 10.1 to 108.7 J/mm.

Unprecedented zeolite-like framework topology constructed from cages with 3-rings in a barium oxonitridophosphate.

PubMed

Sedlmaier, Stefan J; Döblinger, Markus; Oeckler, Oliver; Weber, Johannes; auf der Günne, Jörn Schmedt; Schnick, Wolfgang

2011-08-10

A novel oxonitridophosphate, Ba(19)P(36)O(6+x)N(66-x)Cl(8+x) (x ≈ 4.54), has been synthesized by heating a multicomponent reactant mixture consisting of phosphoryl triamide OP(NH(2))(3), thiophosphoryl triamide SP(NH(2))(3), BaS, and NH(4)Cl enclosed in an evacuated and sealed silica glass ampule up to 750 °C. Despite the presence of side phases, the crystal structure was elucidated ab initio from high-resolution synchrotron powder diffraction data (λ = 39.998 pm) applying the charge flipping algorithm supported by independent symmetry information derived from electron diffraction (ED) and scanning transmission electron microscopy (STEM). The compound crystallizes in the cubic space group Fm ̅3c (no. 226) with a = 2685.41(3) pm and Z = 8. As confirmed by Rietveld refinement, the structure comprises all-side vertex sharing P(O,N)(4) tetrahedra forming slightly distorted 3(8)4(6)8(12) cages representing a novel composite building unit (CBU). Interlinked through their 4-rings and additional 3-rings, the cages build up a 3D network with a framework density FD = 14.87 T/1000 Å(3) and a 3D 8-ring channel system. Ba(2+) and Cl(-) as extra-framework ions are located within the cages and channels of the framework. The structural model is corroborated by (31)P double-quantum (DQ) /single-quantum (SQ) and triple-quantum (TQ) /single-quantum (SQ) 2D correlation MAS NMR spectroscopy. According to (31)P{(1)H} C-REDOR NMR measurements, the H content is less than one H atom per unit cell. © 2011 American Chemical Society

Nano-scale Characterization of Basalt - Quenched Lava and Reheated Products

NASA Astrophysics Data System (ADS)

Burkhard, D. J.; Wirth, R.

2001-12-01

In order to trace the mechanism of crystallization in basalt we investigated basalt lava from active Pu'u O'o, Kilauea, Hawaii with TEM. We considered (1) quenched melt (glass, obtained by dipping a hammer into the lava (April 1996) and subsequent quenching in air), and (2) that glass after reheating for 48 hr at 850° C, and (3) after reheating for 48 hr at 930° C. Previous investigations had illustrated interface-controlled growth of pyroxene and Fe-Ti oxides at 850° C and volumetric growth of these phases in addition to plagioclase above 920° C [1]. In general, (1) is a perfect glass to the nano-scale. Occasional inhomogeneities are identified as plagioclase. With a size of no more than approximately 100 unit cells, these "crystals" might be considered as nuclei. Dendrites of pyroxene, identified on the micron scale with back scattered electrons [1], occur as a sequence of slightly displaced plates with equal orientation on the nano-scale. HREM, diffraction pattern and EDS confirm that this is augite, in agreement with investigations on the micron-scale [1]. Fe-Ti oxides occur isolated in the matrix with a diameter less than 100 nm, in contrast to the micron-scale, where Fe-Ti oxides appear at the apices of augite. In (3) we find in addition plagioclase with thin lamellae, indicating twinning. In (3),augite contains lamellae parallel to (001), and they are identified as pigeonite by HREM and electron diffraction. Pigeonite lamellae occur also in (2), however, less developed. Electron diffraction suggests that reflections of augite correspond to the space group C 2/c, and of exsolved pigeonite to P 21/c, which is a low pigeonite. These exsolution phenomena are undistiguishable from what is usually observed in relation to high cooling rates [e.g. 2]. The stability of pigeonite at these temperatures suggests a Fe/Fe+Mg ratio above 0.6 for pyroxene in the quadilateral [3]. Microprobe analyses [1] suggest ratios of 0.4 to 0.5. [1] Burkhard D.J.M. (2001) J. Petrol. 42, 507-527; [2] Philpotts A.R. (1990) Principles of Igneous and Metamorphic Petrology, Prentice; [3] Lindsley A.(1983) Am. Mineral. 68, 477-493.

Evidence for the suppression of incident beam effects in Auger electron diffraction

NASA Astrophysics Data System (ADS)

Davoli, I.; Gunnella, R.; Bernardini, R.; De Crescenzi, M.

1998-01-01

Auger electron diffraction (AED) of the Cu(100) surface has been studied through the anisotropy of the elastic backdiffused beam electrons, the L 2,3M 4,5M 4,5 (LVV) and the M 2,3M 4,5M 4,5 (MVV) transitions in polar scan along the two main directions [001], [011] and in azimuth scan at normal emission. The intensity anisotropies of the low and high kinetic energy Auger lines are in antiphase to each other as in experiments in which these transitions are excited by X-ray photons. This behaviour has been exploited to single out the origin of the physical mechanisms accompanying the diffraction of the emitted electrons. Incident beam effects appear to be sizeable only when the collection of the AED spectra are made with an angle integrating electron analyser (cylindrical mirror analyser or low electron energy diffraction apparatus), but they appear negligible when electron collection is performed through a small solid-angle detector. The conclusions reached by our measurements are supported by good agreement with experimental and theoretical X-ray photoelectron diffraction data and demonstrate that, when the incident beam energy is sufficiently higher than the kinetic energy of the Auger electron detected, the influence of the incident beam on AED is negligible.

The PROPEL Electrodynamic Tether Mission and Connecting to the Ionosphere

NASA Technical Reports Server (NTRS)

Gilchrist, Brian; Bilen, Sven; Hoyt, Rob; Stone,Nobie; Vaughn, Jason; Fuhrhop, Keith; Krause, Linda; Khazanov, George; Johnson, Les

2012-01-01

The exponential increase of launch system size.and cost.with delta-V makes missions that require large total impulse cost prohibitive. Led by NASA's Marshall Space Flight Center, a team from government, industry, and academia has developed a flight demonstration mission concept of an integrated electrodynamic (ED) tethered satellite system called PROPEL: "Propulsion using Electrodynamics". The PROPEL Mission is focused on demonstrating a versatile configuration of an ED tether to overcome the limitations of the rocket equation, enable new classes of missions currently unaffordable or infeasible, and significantly advance the Technology Readiness Level (TRL) to an operational level. We are also focused on establishing a far deeper understanding of critical processes and technologies to be able to scale and improve tether systems in the future. Here, we provide an overview of the proposed PROPEL mission. One of the critical processes for efficient ED tether operation is the ability to inject current to and collect current from the ionosphere. Because the PROPEL mission is planned to have both boost and deboost capability using a single tether, the tether current must be capable of flowing in both directions and at levels well over 1 A. Given the greater mobility of electrons over that of ions, this generally requires that both ends of the ED tether system can both collect and emit electrons. For example, hollow cathode plasma contactors (HCPCs) generally are viewed as state-of-the-art and high TRL devices; however, for ED tether applications important questions remain of how efficiently they can operate as both electron collectors and emitters. Other technologies will be highlighted that are being investigated as possible alternatives to the HCPC such as Solex that generates a plasma cloud from a solid material (Teflon) and electron emission (only) technologies such as cold-cathode electron field emission or photo-electron beam generation (PEBG) techniques.

Diagnostic accuracy of a screening electronic alert tool for severe sepsis and septic shock in the emergency department.

PubMed

Alsolamy, Sami; Al Salamah, Majid; Al Thagafi, Majed; Al-Dorzi, Hasan M; Marini, Abdellatif M; Aljerian, Nawfal; Al-Enezi, Farhan; Al-Hunaidi, Fatimah; Mahmoud, Ahmed M; Alamry, Ahmed; Arabi, Yaseen M

2014-12-05

Early recognition of severe sepsis and septic shock is challenging. The aim of this study was to determine the diagnostic accuracy of an electronic alert system in detecting severe sepsis or septic shock among emergency department (ED) patients. An electronic sepsis alert system was developed as a part of a quality-improvement project for severe sepsis and septic shock. The system screened all adult ED patients for a combination of systemic inflammatory response syndrome and organ dysfunction criteria (hypotension, hypoxemia or lactic acidosis). This study included all patients older than 14 years who presented to the ED of a tertiary care academic medical center from Oct. 1, 2012 to Jan. 31, 2013. As a comparator, emergency medicine physicians or the critical care physician identified the patients with severe sepsis or septic shock. In the ED, vital signs were manually entered into the hospital electronic heath record every hour in the critical care area and every two hours in other areas. We also calculated the time from the alert to the intensive care unit (ICU) referral. Of the 49,838 patients who presented to the ED, 222 (0.4%) were identified to have severe sepsis or septic shock. The electronic sepsis alert had a sensitivity of 93.18% (95% CI, 88.78% - 96.00%), specificity of 98.44 (95% CI, 98.33% - 98.55%), positive predictive value of 20.98% (95% CI, 18.50% - 23.70%) and negative predictive value of 99.97% (95% CI, 99.95% - 99.98%) for severe sepsis and septic shock. The alert preceded ICU referral by a median of 4.02 hours (Q1 - Q3: 1.25-8.55). Our study shows that electronic sepsis alert tool has high sensitivity and specificity in recognizing severe sepsis and septic shock, which may improve early recognition and management.

Technology Area Roadmap for In-Space Propulsion Technologies

NASA Technical Reports Server (NTRS)

Johnson, Les; Meyer, Michael; Palaszewski, Bryan; Coote, David; Goebel, Dan; White, Harold

2012-01-01

The exponential increase of launch system size.and cost.with delta-V makes missions that require large total impulse cost prohibitive. Led by NASA fs Marshall Space Flight Center, a team from government, industry, and academia has developed a flight demonstration mission concept of an integrated electrodynamic (ED) tethered satellite system called PROPEL: \\Propulsion using Electrodynamics.. The PROPEL Mission is focused on demonstrating a versatile configuration of an ED tether to overcome the limitations of the rocket equation, enable new classes of missions currently unaffordable or infeasible, and significantly advance the Technology Readiness Level (TRL) to an operational level. We are also focused on establishing a far deeper understanding of critical processes and technologies to be able to scale and improve tether systems in the future. Here, we provide an overview of the proposed PROPEL mission. One of the critical processes for efficient ED tether operation is the ability to inject current to and collect current from the ionosphere. Because the PROPEL mission is planned to have both boost and deboost capability using a single tether, the tether current must be capable of flowing in both directions and at levels well over 1 A. Given the greater mobility of electrons over that of ions, this generally requires that both ends of the ED tether system can both collect and emit electrons. For example, hollow cathode plasma contactors (HCPCs) generally are viewed as state-of-the-art and high TRL devices; however, for ED tether applications important questions remain of how efficiently they can operate as both electron collectors and emitters. Other technologies will be highlighted that are being investigated as possible alternatives to the HCPC such as Solex that generates a plasma cloud from a solid material (Teflon) and electron emission (only) technologies such as cold-cathode electron field emission or photo-electron beam generation (PEBG) techniques

Paramagnetic defects in electron-irradiated yttria-stabilized zirconia: Effect of yttria content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah E.

2011-12-20

We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are stronglymore » enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. It is concluded that F+-type centres might be actually oxygen divacancies (F2+-type centres). Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 ± 1 eV with subsequent defect re-arrangement.« less

SEM Microanalysis of Particles: Concerns and Suggestions

NASA Astrophysics Data System (ADS)

Fournelle, J.

2008-12-01

The scanning electron microscope (SEM) is well suited to examine and characterize small (i.e. <10 micron) particles. Particles can be imaged and sizes and shapes determined. With energy dispersive x-ray spectrometers (EDS), chemical compositions can be determined quickly. Despite the ease in acquiring x-ray spectra and chemical compositions, there are potentially major sources of error to be recognized. Problems with EDS analyses of small particles: Qualitive estimates of composition (e.g. stating that Si>Al>Ca>Fe plus O) are easy. However, to be able to have confidence that a chemical composition is accurate, several issues should be examined. (1) Particle Mass Effect: Is the accelerating voltage appropriate for the specimen size? Are all the incident electrons remaining inside the particle, and not traveling out of the sample side or bottom? (2) Particle Absorption Effect: What is the geometric relationship of the beam impact point to the x-ray detector? The x-ray intensity will vary by significant amounts for the same material if the grains are irregular and the path out of the sample in the direction of the detector is longer or shorter. (3) Particle Fluorescence Effect: This is generally a smaller error, but should be considered: for small particles, using large standards, there will be a few % less x-rays generated in a small particle relative to one of the same composition and 50-100 times larger. Also, if the sample sits on a grid of a particular composition (e.g. Si wafer) potentially several % of Si could appear in the analysis. (4) In a increasing number of laboratories, with environmental or variable pressure SEMs, the Gas Skirt Effect is operating against you: here the incident electron beam scatters in the gas in the chamber, with less electrons impacting the target spot and some others hitting grains 100s of microns away, producing spectra that could be faulty. (5) Inclusion of measured oxygen: if the measured oxygen x-ray counts are utilized, significant errors can be introduced by differential absorption of this low energy x-ray. (6) Standardless Analysis: This typical method of doing EDS analysis has a major pitfall: the printed analysis is normalized to 100 wt%, thereby eliminating an important clue to analytical error. Suggestions: (1) Use lower voltage, e.g. 10 kV, reducing effects 1,2,3 above. (2) Use standards--traditional flat polished ones--and don't initially normalize totals. Discrepancies can be observed and addressed, not ignored. (3) Alway include oxygen by stoichometry, not measured. (4) Experimental simulation. Using material of constant composition (e.g. NIST glass K-411, or other homogeneous multi-element material with the elements of interest), grind into fragments of similar size to your unknowns, and see what is the analytical error for measurements of these known particles. Analyses of your unknown material will be no better, and probably worse than that, particularly if the grains are smaller. The results of this experiment should be reported whenever discussing measurements on the unknown materials. (5) Monte Carlo simulation. Programs such PENEPMA allows creation of complex geometry samples (and samples on substrates) and resulting EDS spectra can be generated. This allows estimation of errors for representative cases. It is slow, however; other simulations such as DTSA-II promise faster simulations with some limitations. (6) EBSD: this is a perfectly suited for some problems with SEM identification of small particles, e.g. distinguishing magnetite (Fe3O4) from hematite (Fe2O3), which is virtually impossible to do by EDS. With the appropriate hardware and software, electron diffraction patterns on particles can be gathered and the crystal type determined.

Crystallography and Morphology of Niobium Carbide in As-Cast HP-Niobium Reformer Tubes

NASA Astrophysics Data System (ADS)

Buchanan, Karl G.; Kral, Milo V.

2012-06-01

The microstructures of two as-cast heats of niobium-modified HP stainless steels were characterized. Particular attention was paid to the interdendritic niobium-rich carbides formed during solidification of these alloys. At low magnifications, these precipitates are grouped in colonies of similar lamellae. Higher magnifications revealed that the lamellae actually obtain two distinct morphologies. The type I morphology exhibits broad planar interfaces with a smooth platelike shape. Type II lamellae have undulating interfaces and an overall reticulated shape. To provide further insight into the origin of these two different morphologies, the microstructure and crystallography of each have been studied in detail using high resolution scanning electron microscopy, transmission electron microscopy, various electron diffraction methods (electron backscatter diffraction (EBSD), selected area diffraction (SAD), and convergent beam electron diffraction (CBED)), and energy dispersive X-ray spectroscopy.

Excitation of phonons in medium-energy electron diffraction

NASA Astrophysics Data System (ADS)

Alvarez, M. A. Vicente; Ascolani, H.; Zampieri, G.

1996-03-01

The ``elastic'' backscattering of electrons from crystalline surfaces presents two regimes: a low-energy regime, in which the characteristic low-energy electron diffraction (LEED) pattern is observed, and a medium-energy regime, in which the diffraction pattern is similar to those observed in x-ray photoemission diffraction (XPD) and Auger electron diffraction (AED) experiments. We present a model for the electron scattering which, including the vibrational degrees of freedom of the crystal, contains both regimes and explains the passage from one regime to the other. Our model is based on a separation of the electron and atomic motions (adiabatic approximation) and on a cluster-type formulation of the multiple scattering of the electron. The inelastic scattering events (excitation and/or absorption of phonons) are treated as coherent processes and no break of the phase relation between the incident and the exit paths of the electron is assumed. The LEED and the medium-energy electron diffraction regimes appear naturally in this model as the limit cases of completely elastic scattering and of inelastic scattering with excitation and/or absorption of multiple phonons. Intensity patterns calculated with this model are in very good agreement with recent experiments of electron scattering on Cu(001) at low and medium energies. We show that there is a correspondence between the type of intensity pattern and the mean number of phonons excited and/or absorbed during the scattering: a LEED-like pattern is observed when this mean number is less than 2, LEED-like and XPD/AED-like features coexist when this number is 3-4, and a XPD/AED-like pattern is observed when this number is greater than 5-6.

Microstructure of Haynes® 282® Superalloy after Vacuum Induction Melting and Investment Casting of Thin-Walled Components.

PubMed

Matysiak, Hubert; Zagorska, Malgorzata; Andersson, Joel; Balkowiec, Alicja; Cygan, Rafal; Rasinski, Marcin; Pisarek, Marcin; Andrzejczuk, Mariusz; Kubiak, Krzysztof; Kurzydlowski, Krzysztof J

2013-11-01

The aim of this work was to characterize the microstructure of the as-cast Haynes ® 282 ® alloy. Observations and analyses were carried out using techniques such as X-ray diffraction (XRD), light microscopy (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray spectroscopy (EDS), wave length dispersive X-ray spectroscopy (WDS), auger electron spectroscopy (AES) and electron energy-loss spectrometry (EELS). The phases identified in the as-cast alloy include: γ (gamma matrix), γ' (matrix strengthening phase), (TiMoCr)C (primary carbide), TiN (primary nitride), σ (sigma-TCP phase), (TiMo)₂SC (carbosulphide) and a lamellar constituent consisting of molybdenum and chromium rich secondary carbide phase together with γ phase. Within the dendrites the γ' appears mostly in the form of spherical, nanometric precipitates (74 nm), while coarser (113 nm) cubic γ' precipitates are present in the interdendritic areas. Volume fraction content of the γ' precipitates in the dendrites and interdendritic areas are 9.6% and 8.5%, respectively. Primary nitrides metallic nitrides (MN), are homogeneously dispersed in the as-cast microstructure, while primary carbides metallic carbides (MC), preferentially precipitate in interdendritic areas. Such preference is also observed in the case of globular σ phase. Lamellar constituents characterized as secondary carbides/γ phases were together with (TiMo)₂SC phase always observed adjacent to σ phase precipitates. Crystallographic relations were established in-between the MC, σ, secondary carbides and γ/γ' matrix.

The Independent Gradient Model: A New Approach for Probing Strong and Weak Interactions in Molecules from Wave Function Calculations.

PubMed

Lefebvre, Corentin; Khartabil, Hassan; Boisson, Jean-Charles; Contreras-García, Julia; Piquemal, Jean-Philip; Hénon, Eric

2018-03-19

Extraction of the chemical interaction signature from local descriptors based on electron density (ED) is still a fruitful field of development in chemical interpretation. In a previous work that used promolecular ED (frozen ED), the new descriptor, δg , was defined. It represents the difference between a virtual upper limit of the ED gradient (∇ρIGM , IGM=independent gradient model) that represents a noninteracting system and the true ED gradient (∇ρ ). It can be seen as a measure of electron sharing brought by ED contragradience. A compelling feature of this model is to provide an automatic workflow that extracts the signature of interactions between selected groups of atoms. As with the noncovalent interaction (NCI) approach, it provides chemists with a visual understanding of the interactions present in chemical systems. ∇ρIGM is achieved simply by using absolute values upon summing the individual gradient contributions that make up the total ED gradient. Hereby, we extend this model to relaxed ED calculated from a wave function. To this end, we formulated gradient-based partitioning (GBP) to assess the contribution of each orbital to the total ED gradient. We highlight these new possibilities across two prototypical examples of organic chemistry: the unconventional hexamethylbenzene dication, with a hexa-coordinated carbon atom, and β-thioaminoacrolein. It will be shown how a bond-by-bond picture can be obtained from a wave function, which opens the way to monitor specific interactions along reaction paths. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A study on the enhancement of opto-electronic properties of CdS thin films: seed-assisted fabrication

NASA Astrophysics Data System (ADS)

Kumarage, W. G. C.; Wijesundera, R. P.; Seneviratne, V. A.; Jayalath, C. P.; Dassanayake, B. S.

2017-04-01

A novel method of fabricating chemical bath deposited CdS thin films (CBD-CdS) by using electrodeposited CdS (ED-CdS) as a seed layer is reported. The resulting thin, compact, uniform and adherent seed-assisted CdS films (ED/CBD-CdS) show enhanced effective surface area compared to both ED-CdS and CBD-CdS. The phase of these CdS films was determined to be hexagonal. The fabricated ED/CBD-CdS films show higher photoelectrochemical (PEC) cell efficiency than either ED-CdS and CBD-CdS thin films. Carrier concentration and flat band potential values for ED/CBD-CdS systems are also found to be superior compared to both ED-CdS and CBD-CdS systems.

Electronic decision support in general practice. What's the hold up?

PubMed

Liaw, S T; Schattner, P

2003-11-01

The uptake of computers in Australian general practice has been for administrative use and prescribing, but the development of electronic decision support (EDS) has been particularly slow. Therefore, computers are not being used to their full potential in assisting general practitioners to care for their patients. This article examines current barriers to EDS in general practice and possible strategies to increase its uptake. Barriers to the uptake of EDS include a lack of a business case, shifting of costs for data collection and management to the clinician, uncertainty about the optimal level of decision support, lack of technical and semantic standards, and resistance to EDS use by the time conscious GP. There is a need for a more strategic and attractive incentives program, greater national coordination, and more effective collaboration between government, the computer industry and the medical profession if current inertia is to be overcome.

Diffraction effects and inelastic electron transport in angle-resolved microscopic imaging applications.

PubMed

Winkelmann, A; Nolze, G; Vespucci, S; Naresh-Kumar, G; Trager-Cowan, C; Vilalta-Clemente, A; Wilkinson, A J; Vos, M

2017-09-01

We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes of the backscattered electron distribution which we identify as the dominant mechanism underlying pseudocolour orientation imaging using multiple, angle-resolving detectors. Consequently, diffraction effects of the incident beam and their impact on the subsequent coherent and incoherent electron transport need to be taken into account for an in-depth theoretical modelling of the energy- and momentum distribution of electrons backscattered from crystalline sample regions. Our findings have implications for the level of theoretical detail that can be necessary for the interpretation of complex imaging modalities such as electron channelling contrast imaging (ECCI) of defects in crystals. If the solid angle of detection is limited to specific regions of the backscattered electron momentum distribution, the image contrast that is observed in ECCI and similar applications can be strongly affected by incident beam diffraction and topographic effects from the sample surface. As an application, we demonstrate characteristic changes in the resulting images if different properties of the backscattered electron distribution are used for the analysis of a GaN thin film sample containing dislocations. © 2017 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA.

PubMed

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-05-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the `diffraction before destruction' scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles.

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA

PubMed Central

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-01-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the ‘diffraction before destruction’ scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles. PMID:24763651

A compact electron gun for time-resolved electron diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A., E-mail: derek.wann@york.ac.uk

A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolutionmore » of the diffraction pattern.« less

Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

NASA Astrophysics Data System (ADS)

He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

2013-02-01

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

On the error in the nucleus-centered multipolar expansion of molecular electron density and its topology: A direct-space computational study.

PubMed

Michael, J Robert; Koritsanszky, Tibor

2017-05-28

The convergence of nucleus-centered multipolar expansion of the quantum-chemical electron density (QC-ED), gradient, and Laplacian is investigated in terms of numerical radial functions derived by projecting stockholder atoms onto real spherical harmonics at each center. The partial sums of this exact one-center expansion are compared with the corresponding Hansen-Coppens pseudoatom (HC-PA) formalism [Hansen, N. K. and Coppens, P., "Testing aspherical atom refinements on small-molecule data sets," Acta Crystallogr., Sect. A 34, 909-921 (1978)] commonly utilized in experimental electron density studies. It is found that the latter model, due to its inadequate radial part, lacks pointwise convergence and fails to reproduce the local topology of the target QC-ED even at a high-order expansion. The significance of the quantitative agreement often found between HC-PA-based (quadrupolar-level) experimental and extended-basis QC-EDs can thus be challenged.

Modifications and integration of the electronic tracking board in a pediatric emergency department.

PubMed

Dexheimer, Judith W; Kennebeck, Stephanie

2013-07-01

Electronic health records (EHRs) are used for data storage; provider, laboratory, and patient communication; clinical decision support; procedure and medication orders; and decision support alerts. Clinical decision support is part of any EHR and is designed to help providers make better decisions. The emergency department (ED) poses a unique environment to the use of EHRs and clinical decision support. Used effectively, computerized tracking boards can help improve flow, communication, and the dissemination of pertinent visit information between providers and other departments in a busy ED. We discuss the unique modifications and decisions made in the implementation of an EHR and computerized tracking board in a pediatric ED. We discuss the changing views based on provider roles, customization to the user interface including the layout and colors, decision support, tracking board best practices collected from other institutions and colleagues, and a case study of using reminders on the electronic tracking board to drive pain reassessments.

On the error in the nucleus-centered multipolar expansion of molecular electron density and its topology: A direct-space computational study

NASA Astrophysics Data System (ADS)

Michael, J. Robert; Koritsanszky, Tibor

2017-05-01

The convergence of nucleus-centered multipolar expansion of the quantum-chemical electron density (QC-ED), gradient, and Laplacian is investigated in terms of numerical radial functions derived by projecting stockholder atoms onto real spherical harmonics at each center. The partial sums of this exact one-center expansion are compared with the corresponding Hansen-Coppens pseudoatom (HC-PA) formalism [Hansen, N. K. and Coppens, P., "Testing aspherical atom refinements on small-molecule data sets," Acta Crystallogr., Sect. A 34, 909-921 (1978)] commonly utilized in experimental electron density studies. It is found that the latter model, due to its inadequate radial part, lacks pointwise convergence and fails to reproduce the local topology of the target QC-ED even at a high-order expansion. The significance of the quantitative agreement often found between HC-PA-based (quadrupolar-level) experimental and extended-basis QC-EDs can thus be challenged.

Calcination Method Synthesis of SnO2/g-C3N4 Composites for a High-Performance Ethanol Gas Sensing Application

PubMed Central

Cao, Jianliang; Qin, Cong; Wang, Yan; Zhang, Bo; Gong, Yuxiao; Zhang, Huoli; Sun, Guang; Bala, Hari; Zhang, Zhanying

2017-01-01

The SnO2/g-C3N4 composites were synthesized via a facile calcination method by using SnCl4·5H2O and urea as the precursor. The structure and morphology of the as-synthesized composites were characterized by the techniques of X-ray diffraction (XRD), the field-emission scanning electron microscopy and transmission electron microscopy (SEM and TEM), energy dispersive spectrometry (EDS), thermal gravity and differential thermal analysis (TG-DTA), and N2-sorption. The analysis results indicated that the as-synthesized samples possess the two dimensional structure. Additionally, the SnO2 nanoparticles were highly dispersed on the surface of the g-C3N4nanosheets. The gas-sensing performance of the as-synthesized composites for different gases was tested. Moreover, the composite with 7 wt % g-C3N4 content (SnO2/g-C3N4-7) SnO2/g-C3N4-7 exhibits an admirable gas-sensing property to ethanol, which possesses a higher response and better selectivity than that of the pure SnO2-based sensor. The high surface area of the SnO2/g-C3N4 composite and the good electronic characteristics of the two dimensional graphitic carbon nitride are in favor of the elevated gas-sensing property. PMID:28468245

Enhanced sunlight-driven photocatalytic performance of Bi-doped CdMoO4 benefited from efficient separation of photogenerated charge pairs

NASA Astrophysics Data System (ADS)

Huang, Jiao; Liu, Huanhuan; Zhong, Junbo; Yang, Qi; Chen, Jiufu; Li, Jianzhang; Ma, Dongmei; duan, Ran

2018-06-01

In this paper, to further boost the photocatalytic performance of CdMoO4, Bi3+ was successfully doped into CdMoO4 by a facile microwave hydrothermal method. The Bi-doped CdMoO4 photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron spin-resonance (ESR) and surface photovoltage spectroscopy (SPS). The results exhibit that doping Bi3+ into CdMoO4 remarkably boosts the separation rate of photoinduced charge pairs and the specific surface area, decrease the crystal size, narrows the band gap of the CdMoO4 and induces the binding energy shift of Cd, all these advantageous factors result in the promoted photocatalytic performance of CdMoO4. Using rhodamine B (RhB) as model toxic pollutant, the photocatalytic activities of the photocatalysts were evaluated under a 500 W Xe lamp irradiation. When the molar ratio of Bi/Cd is 0.2%, Bi-CdMoO4 prepared displays the best photocatalytic performance, the photocatalytic performance of the 0.2% sample is more than twice of that of the reference CdMoO4.

Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

NASA Astrophysics Data System (ADS)

Sagadevan, Suresh; Zaman Chowdhury, Zaira; Enamul Hoque, Md; Podder, Jiban

2017-11-01

In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV-visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

Diffraction and microscopy with attosecond electron pulse trains

NASA Astrophysics Data System (ADS)

Morimoto, Yuya; Baum, Peter

2018-03-01

Attosecond spectroscopy1-7 can resolve electronic processes directly in time, but a movie-like space-time recording is impeded by the too long wavelength ( 100 times larger than atomic distances) or the source-sample entanglement in re-collision techniques8-11. Here we advance attosecond metrology to picometre wavelength and sub-atomic resolution by using free-space electrons instead of higher-harmonic photons1-7 or re-colliding wavepackets8-11. A beam of 70-keV electrons at 4.5-pm de Broglie wavelength is modulated by the electric field of laser cycles into a sequence of electron pulses with sub-optical-cycle duration. Time-resolved diffraction from crystalline silicon reveals a < 10-as delay of Bragg emission and demonstrates the possibility of analytic attosecond-ångström diffraction. Real-space electron microscopy visualizes with sub-light-cycle resolution how an optical wave propagates in space and time. This unification of attosecond science with electron microscopy and diffraction enables space-time imaging of light-driven processes in the entire range of sample morphologies that electron microscopy can access.

Ab initio structure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genderen, E. van; Clabbers, M. T. B.; Center for Cellular Imaging and NanoAnalytics

A specialized quantum area detector for electron diffraction studies makes it possible to solve the structure of small organic compound nanocrystals in non-cryo conditions by direct methods. Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enabling ab initio phasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e{sup −} Å{sup −2} s{sup −1}) were collected at roommore » temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS, SHELX) and for electron crystallography (ADT3D/PETS, SIR2014)« less

Two-dimensional mapping of polarizations of rhombohedral nanostructures in the orthorhombic phase of KNbO3 by the combined use of scanning transmission electron microscopy and convergent-beam electron diffraction

NASA Astrophysics Data System (ADS)

Tsuda, Kenji; Tanaka, Michiyoshi

2015-08-01

Rhombohedral nanostructures previously found in the orthorhombic phase of KNbO3, by convergent-beam electron diffraction [Tsuda et al., Appl. Phys. Lett. 102, 051913 (2013)], have been investigated by the combined use of scanning transmission electron microscopy and convergent-beam electron diffraction. Two-dimensional distributions of the rhombohedral nanostructures, or nanometer-scale spatial fluctuations of polarization clusters, have been successfully visualized. The correlation length of the observed spatial fluctuations of local polarizations is related to the cpc/apc ratio and the transition entropy.

Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry for quick detection of sulfur-oxidizing bacteria in environmental water samples

NASA Astrophysics Data System (ADS)

Sun, Chengjun; Jiang, Fenghua; Gao, Wei; Li, Xiaoyun; Yu, Yanzhen; Yin, Xiaofei; Wang, Yong; Ding, Haibing

2017-01-01

Detection of sulfur-oxidizing bacteria has largely been dependent on targeted gene sequencing technology or traditional cell cultivation, which usually takes from days to months to carry out. This clearly does not meet the requirements of analysis for time-sensitive samples and/or complicated environmental samples. Since energy-dispersive X-ray spectrometry (EDS) can be used to simultaneously detect multiple elements in a sample, including sulfur, with minimal sample treatment, this technology was applied to detect sulfur-oxidizing bacteria using their high sulfur content within the cell. This article describes the application of scanning electron microscopy imaging coupled with EDS mapping for quick detection of sulfur oxidizers in contaminated environmental water samples, with minimal sample handling. Scanning electron microscopy imaging revealed the existence of dense granules within the bacterial cells, while EDS identified large amounts of sulfur within them. EDS mapping localized the sulfur to these granules. Subsequent 16S rRNA gene sequencing showed that the bacteria detected in our samples belonged to the genus Chromatium, which are sulfur oxidizers. Thus, EDS mapping made it possible to identify sulfur oxidizers in environmental samples based on localized sulfur within their cells, within a short time (within 24 h of sampling). This technique has wide ranging applications for detection of sulfur bacteria in environmental water samples.

Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

2017-07-01

In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

The influence of sequence of precursor films on CZTSe thin films prepared by ion-beam sputtering deposition

NASA Astrophysics Data System (ADS)

Zhao, Jun; Liang, Guangxing; Zeng, Yang; Fan, Ping; Hu, Juguang; Luo, Jingting; Zhang, Dongping

2017-02-01

The CuZnSn (CZT) precursor thin films are grown by ion-beam sputtering Cu, Zn, Sn targets with different orders and then sputtering Se target to fabricate Cu2ZnSnSe4 (CZTSe) absorber thin films on molybdenum substrates. They are annealed in the same vacuum chamber at 400 °C. The characterization methods of CZTSe thin films include X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray photoelectron spectra (XPS) in order to study the crystallographic properties, composition, surface morphology, electrical properties and so on. The results display that the CZTSe thin films got the strongest diffraction peak intensity and were with good crystalline quality and its morphology appeared smooth and compact with a sequence of Cu/Zn/Sn/Se, which reveals that the expected states for CZTSe are Cu1+, Zn2+, Sn4+, Se2+. With the good crystalline quality and close to ideal stoichiometric ratio the resistivity of the CZTSe film with the sequence of Cu/Zn/Sn/Se is lower, whose optical band gap is about 1.50 eV. Project supported by the National Natural Science Foundation of China (No. 61404086), the Basical Research Program of Shenzhen (Nos. JCYJ20150324140036866, JCYJ20150324141711581), and the Natural Science Foundation of SZU (No. 2014017).

Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

ERIC Educational Resources Information Center

Velentzas, Athanasios

2014-01-01

Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such…

Exploring transmission Kikuchi diffraction using a Timepix detector

NASA Astrophysics Data System (ADS)

Vespucci, S.; Winkelmann, A.; Mingard, K.; Maneuski, D.; O'Shea, V.; Trager-Cowan, C.

2017-02-01

Electron backscatter diffraction (EBSD) is a well-established scanning electron microscope (SEM)-based technique [1]. It allows the non-destructive mapping of the crystal structure, texture, crystal phase and strain with a spatial resolution of tens of nanometers. Conventionally this is performed by placing an electron sensitive screen, typically consisting of a phosphor screen combined with a charge coupled device (CCD) camera, in front of a specimen, usually tilted 70° to the normal of the exciting electron beam. Recently, a number of authors have shown that a significant increase in spatial resolution is achievable when Kikuchi diffraction patterns are acquired in transmission geometry; that is when diffraction patterns are generated by electrons transmitted through an electron-transparent, usually thinned, specimen. The resolution of this technique, called transmission Kikuchi diffraction (TKD), has been demonstrated to be better than 10 nm [2,3]. We have recently demonstrated the advantages of a direct electron detector, Timepix [4,5], for the acquisition of standard EBSD patterns [5]. In this article we will discuss the advantages of Timepix to perform TKD and for acquiring spot diffraction patterns and more generally for acquiring scanning transmission electron microscopy micrographs in the SEM. Particularly relevant for TKD, is its very compact size, which allows much more flexibility in the positioning of the detector in the SEM chamber. We will furthermore show recent results using Timepix as a virtual forward scatter detector, and will illustrate the information derivable on producing images through processing of data acquired from different areas of the detector. We will show results from samples ranging from gold nanoparticles to nitride semiconductor nanorods.

Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zieliński, W., E-mail: wiziel@inmat.pw.edu.pl; Płociński, T.; Kurzydłowski, K.J.

2015-06-15

We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens preparedmore » by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.« less

Atomic-scale diffractive imaging of sub-cycle electron dynamics in condensed matter

PubMed Central

Yakovlev, Vladislav S.; Stockman, Mark I.; Krausz, Ferenc; Baum, Peter

2015-01-01

For interaction of light with condensed-matter systems, we show with simulations that ultrafast electron and X-ray diffraction can provide a time-dependent record of charge-density maps with sub-cycle and atomic-scale resolutions. Using graphene as an example material, we predict that diffraction can reveal localised atomic-scale origins of optical and electronic phenomena. In particular, we point out nontrivial relations between microscopic electric current and density in undoped graphene. PMID:26412407

Atomic-scale diffractive imaging of sub-cycle electron dynamics in condensed matter

DOE PAGES

Yakovlev, Vladislav S.; Stockman, Mark I.; Krausz, Ferenc; ...

2015-09-28

For interaction of light with condensed-matter systems, we show with simulations that ultrafast electron and X-ray diffraction can provide a time-dependent record of charge-density maps with sub-cycle and atomic-scale resolutions. Using graphene as an example material, we predict that diffraction can reveal localised atomic-scale origins of optical and electronic phenomena. Here, we point out nontrivial relations between microscopic electric current and density in undoped graphene.

Information technology improves Emergency Department patient discharge instructions completeness and performance on a national quality measure: a quasi-experimental study.

PubMed

Bell, E J; Takhar, S S; Beloff, J R; Schuur, J D; Landman, A B

2013-01-01

To compare the completeness of Emergency Department (ED) discharge instructions before and after introduction of an electronic discharge instructions module by scoring compliance with the Centers for Medicare and Medicaid Services (CMS) Outpatient Measure 19 (OP-19). We performed a quasi-experimental study examining the impact of an electronic discharge instructions module in an academic ED. Three hundred patients discharged home from the ED were randomly selected from two time intervals: 150 patients three months before and 150 patients three to five months after implementation of the new electronic module. The discharge instructions for each patient were reviewed, and compliance for each individual OP-19 element as well as overall OP-19 compliance was scored per CMS specifications. Compliance rates as well as risk ratios (RR) and risk differences (RD) with 95% confidence intervals (CI) comparing the overall OP-19 scores and individual OP-19 element scores of the electronic and paper-based discharge instructions were calculated. The electronic discharge instructions had 97.3% (146/150) overall OP-19 compliance, while the paper-based discharge instructions had overall compliance of 46.7% (70/150). Electronic discharge instructions were twice as likely to achieve overall OP-19 compliance compared to the paper-based format (RR: 2.09, 95% CI: 1.75 - 2.48). The largest improvement was in documentation of major procedures and tests performed: only 60% of the paper-based discharge instructions satisfied this criterion, compared to 100% of the electronic discharge instructions (RD: 40.0%, 95% CI: 32.2% - 47.8%). There was a modest difference in medication documentation with 92.7% for paper-based and 100% for electronic formats (RD: 7.3%, 95% CI: 3.2% - 11.5%). There were no statistically significant differences in documentation of patient care instructions and diagnosis between paper-based and electronic formats. With careful design, information technology can improve the completeness of ED patient discharge instructions and performance on the OP-19 quality measure.

Track structure of protons and other light ions in liquid water: applications of the LIonTrack code at the nanometer scale.

PubMed

Bäckström, G; Galassi, M E; Tilly, N; Ahnesjö, A; Fernández-Varea, J M

2013-06-01

The LIonTrack (Light Ion Track) Monte Carlo (MC) code for the simulation of H(+), He(2+), and other light ions in liquid water is presented together with the results of a novel investigation of energy-deposition site properties from single ion tracks. The continuum distorted-wave formalism with the eikonal initial state approximation (CDW-EIS) is employed to generate the initial energy and angle of the electrons emitted in ionizing collisions of the ions with H2O molecules. The model of Dingfelder et al. ["Electron inelastic-scattering cross sections in liquid water," Radiat. Phys. Chem. 53, 1-18 (1998); "Comparisons of calculations with PARTRAC and NOREC: Transport of electrons in liquid water," Radiat. Res. 169, 584-594 (2008)] is linked to the general-purpose MC code PENELOPE/penEasy to simulate the inelastic interactions of the secondary electrons in liquid water. In this way, the extended PENELOPE/penEasy code may provide an improved description of the 3D distribution of energy deposits (EDs), making it suitable for applications at the micrometer and nanometer scales. Single-ionization cross sections calculated with the ab initio CDW-EIS formalism are compared to available experimental values, some of them reported very recently, and the theoretical electronic stopping powers are benchmarked against those recommended by the ICRU. The authors also analyze distinct aspects of the spatial patterns of EDs, such as the frequency of nearest-neighbor distances for various radiation qualities, and the variation of the mean specific energy imparted in nanoscopic targets located around the track. For 1 MeV/u particles, the C(6+) ions generate about 15 times more clusters of six EDs within an ED distance of 3 nm than H(+). On average clusters of two to three EDs for 1 MeV/u H(+) and clusters of four to five EDs for 1 MeV/u C(6+) could be expected for a modeling double strand break distance of 3.4 nm.

Effect of P, Na, Mg, and Ag content on the in vitro bioactivity, wettability and mechanical strength of sol-gel glasses

NASA Astrophysics Data System (ADS)

Bouhazma, S.; Chajri, S.; Herradi, S.; Khaldi, M.; El Hachadi, A.; El Bali, B.; Lachkar, M.

2018-03-01

Bioactive glasses of the type SiO2-CaO, SiO 2 -CaO-P2O5, and SiO2-CaO-P2O5-MO (M = Na, Mg, or Ag) were obtained by the sol-gel processing method. The obtained materials was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Contact angle and surface tension variation with time were determined at 25°C, respectively, by the sessile and pendant drop techniques, for distinct testing liquids: water, diiodomethane, formamide, and simulated body fluid (SBF). The in vitro studies showed that all gel-glasses compositions produced were bioactive. In the present work, three effects of elements (Mg, Na, Ag) in the glass were detected: (i) good mechanical strength with satisfactory biodegradability, (ii) formation of hydroxyapatite, which may promote good bone bonding and (iii) the good wettability.

High-Temperature Oxidation of Fe3Al Intermetallic Alloy Prepared by Additive Manufacturing LENS

PubMed Central

Łyszkowski, Radosław

2015-01-01

The isothermal oxidation of Fe-28Al-5Cr (at%) intermetallic alloy microalloyed with Zr and B (<0.08 at%) in air atmosphere, in the temperature range of 1000 to 1200 °C, was studied. The investigation was carried out on the thin-walled (<1 mm) elements prepared by Laser Engineered Net Shaping (LENS) from alloy powder of a given composition. Characterization of the specimens, after the oxidation, was conducted using X-ray diffraction (XRD) and scanning electron microscopy (SEM, with back-scatter detector (BSE) and energy-dispersive X-ray spectroscopy (EDS) attachments). The investigation has shown, that the oxidized samples were covered with a thin, homogeneous α-Al2O3 oxide layers. The intensity of their growth indicates that the material lost its resistance to oxidation at 1200 °C. Structural analysis of the thin-walled components’ has not shown intensification of the oxidation process at the joints of additive layers. PMID:28788014

Characterization of Low-Symmetry Structures from Phase Equilibrium of Fe-Al System-Microstructures and Mechanical Properties.

PubMed

Matysik, Piotr; Jóźwiak, Stanisław; Czujko, Tomasz

2015-03-04

Fe-Al intermetallic alloys with aluminum content over 60 at% are in the area of the phase equilibrium diagram that is considerably less investigated in comparison to the high-symmetry Fe₃Al and FeAl phases. Ambiguous crystallographic information and incoherent data referring to the phase equilibrium diagrams placed in a high-aluminum range have caused confusions and misinformation. Nowadays unequivocal material properties description of FeAl₂, Fe₂Al₅ and FeAl₃ intermetallic alloys is still incomplete. In this paper, the influence of aluminum content and processing parameters on phase composition is presented. The occurrence of low-symmetry FeAl₂, Fe₂Al₅ and FeAl₃ structures determined by chemical composition and phase transformations was defined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) examinations. These results served to verify diffraction investigations (XRD) and to explain the mechanical properties of cast materials such as: hardness, Young's modulus and fracture toughness evaluated using the nano-indentation technique.

Sulfated Titania-Silica Reinforced Nafion Nanocomposite Membranes for Proton Exchange Membrane Fuel Cells.

PubMed

Abu Sayeed, M D; Kim, Hee Jin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

2015-09-01

Sulfated titania-silica (SO4(2-)-/TiO2-SiO2) composites were prepared by a sol-gel method with sulfate reaction and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The nanometric diameter and geometry of the sulfated titania-silica (STS) was investigated by transmission electron microscopy (TEM). A small amount of the STS composite in the range of 0.5-3 wt% was then added as reinforcing into the Nafion membrane by water-assisted solution casting method to prepare STS reinforced Nafion nanocomposite membranes (STS-Nafion nanocomposite membranes). The additional functional groups, sulfate groups, of the nanocomposite membrane having more surface oxygenated groups enhanced the fuel cell membrane properties. The STS-Nafion nanocomposite membranes exhibited improved water uptake compared to that of neat Nafion membranes, whereas methanol uptake values were decreased dramatically improved thermal property of the prepared nanocomposite membranes were measured by thermogravimetric analysis (TGA). Furthermore, increased ion exchange capacity values were obtained by thermoacidic pretreatment of the nanocomposite membranes.

Structure, crystallization and dielectric resonances in 2-13 GHz of waste-derived glass-ceramic

NASA Astrophysics Data System (ADS)

Yao, Rui; Liao, SongYi; Chen, XiaoYu; Wang, GuangRong; Zheng, Feng

2016-12-01

Structure, kinetics of crystallization, and dielectric resonances of waste-derived glass-ceramic prepared via quench-heating route were studied as a function of dosage of iron ore tailing (IOT) within 20-40 wt% using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vector network analyzer (VNA) measurements. The glass-ceramic mainly consisted of ferrite crystals embedded in borosilicate glass matrix. Crystallization kinetics and morphologies of ferrite crystals as well as coordination transformation of boron between [BO4] and [BO3] in glass network were adjustable by changing the amount of IOT. Dielectric resonances in 6-13 GHz were found to be dominated by oscillations of Ca2+ cations in glass network with [SiO4] units on their neighboring sites. Ni2+ ions made a small contribution to those resonances. Diopside formed when IOT exceeded 35 wt%, which led to weakening of the resonances.

UV shielding with visible transparency based properties of poly (styrene-co-acrylonitrile)/Ag doped ZnO nanocomposite

NASA Astrophysics Data System (ADS)

Singh, Rajender; Verma, Karan; Singh, Tejbir; Barman, P. B.; Sharma, Dheeraj

2018-02-01

Development of ultraviolet (UV) shielding with visible transparency based thermoplastic polymer nanocomposite (PNs) presents an important requisite in terms of their efficiency and cost. Present study contributed for the same approach by dispersion of Ag doped ZnO nanoparticles upto 10 wt% in poly (styrene-co-acrylonitrile) matrix by insitu emulsion polymerization method. The crystal and chemical structure of PNs has been analyzed by x-ray diffraction (XRD) and fourier infrared spectrometer (FTIR) techniques. The morphological and elemental information of synthesized nanomaterial has been studied by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) technique. The optical properties of PNs has been studied by UV-visible spectroscopy technique. The incorporation of nanoparticles in polymer matrix absorb the complete UV light with visible transparency. The present reported polymer nanocomposite (PNs) have tuned refractive index with UV blocking and visible transparency based properties which can serve as a viable alternative as compared to related conventional materials.

A multi-analytical approach for the characterization of wall painting materials on contemporary buildings

NASA Astrophysics Data System (ADS)

Magrini, Donata; Bracci, Susanna; Cantisani, Emma; Conti, Claudia; Rava, Antonio; Sansonetti, Antonio; Shank, Will; Colombini, MariaPerla

2017-02-01

Samples from Keith Haring's wall painting of the Necker Children Hospital in Paris were studied by a multi-analytical protocol. X-ray fluorescence (XRF), powder X-ray diffraction (XRDP), Electron microscope (SEM-EDS), Infrared and Raman spectroscopy (μ-FT-IR and μ-Raman) measurements were performed in order to characterize the materials and to identify the art technique used to produce this contemporary work. Materials from the mural suffered from severe detachments of materials and several fragments were found on the ground beneath. Some of these fragments, which were representative of the whole palette and stratigraphic sequence, were collected and studied. The fragments were sufficiently large to enable non-invasive measurements to be performed in order to characterize the materials. A comparison of the data of the techniques applied revealed that Haring's palette was composed of organic pigments such as Naphtol red, phthalocyanine blue and green and Hansa yellow, in accordance with those used previously by the artist in other painted murals.

Photosensitized synthesis of silver nanoparticles using Withania somnifera leaf powder and silver nitrate.

PubMed

Raut, Rajesh Warluji; Mendhulkar, Vijay Damodhar; Kashid, Sahebrao Balaso

2014-03-05

The metal nanoparticle synthesis is highly explored field of nanotechnology. The biological methods seem to be more effective; however, due to slow reduction rate and polydispersity of the resulting products, they are less preferred. In the present study, we report rapid and facile synthesis of silver nanoparticles at room temperature. The exposure of reaction mixtures containing silver nitrate and dried leaf powder of Withania somnifera Linn to direct sunlight resulted in reduction of metal ions within five minutes whereas, the dark exposure took almost 12h. Further studies using different light filters reveal the role of blue light in reduction of silver ions. The synthesized silver nanoparticles were characterized by UV-Vis, Infrared spectroscopy (IR), Transmission Electron Microscopy (TEM), X-ray Diffraction studies (XRD), Nanoparticle Tracking Analysis (NTA), Energy Dispersive Spectroscopy (EDS), and Cyclic Voltammetry (CV). The Antibacterial and antifungal studies showed significant activity as compared to their respective standards. Copyright © 2014 Elsevier B.V. All rights reserved.

HVOF coatings of Diamalloy 2002 and Diamalloy 4010 onto steel: Tensile and bending response of coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Shehri, Y. A.; Hashmi, M. S. J.; Yilbas, B. S.

HVOF coating of Diamalloy 2002 powders and Diamalloy 4010 powders as well as two-layered coatings consisting of these powders is carried out. In the two-layered structure, Diamalloy 4010 is sprayed at the substrate surface while Diamalloy 2002 is sprayed on the top of Diamalloy 4010 coating. The mechanical properties of the coatings are examined through tensile and three-point bending tests. The coating microstructure and morphology are examined using the Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD). It is found that the coating produced is free from defects including voids and cracks. The failure mechanism ofmore » coating during tensile and three-point bending tests is mainly crack formation and propagation in the coating. The elastic modulus of coating produced from Diamalloy 2002 is higher than that of Diamalloy 4010 coating, which is due to the presence of 12% WC in the coating.« less

Characterization of Low Firing Temperature Ceramic Glaze Using Phuket MSW and Soda Lime Cullet

NASA Astrophysics Data System (ADS)

Ketboonruang, P.; Jinawat, S.; Kashima, D. P.; Wasanapiarnpong, T.; Sujaridworakun, P.; Buggakuptav, W.; Traipol, N.; Jiemsirilers, S.

2011-10-01

The normal firing temperature of ceramic products is around 1200 °C. In order to reduce firing temperature, industrial wastes were utilized in ceramic glaze. Phuket municipal solid waste (MSW), soda lime cullet, and borax were used as raw materials for low firing temperature glazes. The glaze compositions were designed using a triaxial diagram. Stoneware ceramic body was glazed then fired at 1000 and 1150 °C for 15 minutes. Morphology and phase composition of glazes were analyzed by Scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Thermal expansion compatibility of Stoneware body and glazes were investigated using a dilatometer. Melting behaviour of selected glaze was analyzed by heating stage microscopy. Phuket MSW and Soda lime glass cullet can be used in high percentage as major raw materials for low firing temperature ceramic glaze that show good texture and vitrified at lower firing temperature without using any commercial ceramic frits. The firing temperature can be reduced up to 150 °C in this study.

Decolorization of reactive dye using a photo-ferrioxalate system with brick grain-supported iron oxide.

PubMed

Cheng, Hui-Pin; Huang, Yao-Hui; Lee, Changha

2011-04-15

The photocatalytic activity of a brick grain-supported iron oxide (denoted as B1) was tested for its activity to degrade Reactive Black 5 (RB5) in the presence of oxalic acid. B1 was obtained as a solid waste from a wastewater treatment plant, and characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N(2) adsorption/desorption isotherm analyses. The decolorization experiments were performed in a fluidized bed reactor with aeration under UV-A irradiation (λ = 365 nm). The effects of various factors such as solution pH, concentration of oxalic acid and dissolved oxygen on the decolorization of RB5 were evaluated considering the contributions of adsorption and photo-catalytic degradation. The role of dissolved iron in the removal of RB5 and the stability of B1 were also examined. In addition, the removal of TOC during the photo-catalytic reaction was monitored. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis of silver nanoparticles by silver salt reduction and its characterization

NASA Astrophysics Data System (ADS)

Muzamil, Muhammad; Khalid, Naveed; Danish Aziz, M.; Aun Abbas, S.

2014-06-01

The wet chemical method route by metal salt reduction has been used to synthesize nanoparticles, using silver nitrate as an inorganic salt, aldehyde as a reducing agent and amino acid as a catalyst. During the reaction aldehyde oxidizes to carboxylic acid and encapsulates the silver nanoparticles to prevent agglomeration and provide barrier in the growth of particle. The existing work produces particles using lab grade chemical, here the presented work is by using industrial grade chemicals to make the process more cost & time effective. The nano silver powder has been studied for their formation, particle size, shape & compositional analysis using Scanning Electron Microscope (SEM) equipped with EDS. The particles size distributions were analyzed by Laser Particle Analyzer (LPA), structure & morphological analysis using x-ray diffraction (XRD) and Fourier-transform-infrared Spectroscopy (FTIR) confirmed the stabilization of particles by coating of carboxylic group. These studies infer that the particles are mostly spherical in shape and have an average size between 70 to 350 nm.

Characterization and Evaluation of Ti-Zr-V Non-evaporable Getter Films Used in Vacuum Systems

NASA Astrophysics Data System (ADS)

Ferreira, M. J.; Seraphim, R. M.; Ramirez, A. J.; Tabacniks, M. H.; Nascente, P. A. P.

Among several methods used to obtain ultra-high vacuum (UHV) for particles accelerators chambers, it stands out the internal coating with metallic films capable of absorbing gases, called NEG (non-evaporable getter). Usually these materials are constituted by elements of great chemical reactivity and solubility (such as Ti, Zr, and V), at room temperature for oxygen and other gases typically found in UHV, such as H2, CO, and CO2. Gold and ternary Ti-Zr-V films were produced by magnetron sputtering, and their composition, structure, morphology, and aging characteristics were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission gun sc anning electronmicroscopy (FEG-SEM), atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM). The comparison between the produced films and commercial samples indicated that the desirable characteristics depend on the nanometric structure of the films and that this structure is sensitive to the heat treatments.

Morphological Comparison of U3O8 Ore Concentrates from Canada Key Lake and Namibia Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Daniel S.; Tandon, Lav; Martinez, Patrick Thomas

Uranium ore concentrates from two different sources were examined using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The ore powders are referred to as Namibia (id. no. 90036, LIMS id. no. 18775) and Canada Key Lake (id. no. 90019, LIMS id. no. 18774). Earlier work identified the ores as the U₃O₈ phase of uranium oxide using x-ray diffraction. Both sets of powders were in the form of dark brown to black powder fines. However, the Canada Key Lake concentrates contained larger chunks of material on the millimeter scale that were easily visible to the unaided eye. The powdersmore » were mounted for SEM examination by hand dispersing a small amount onto conductive sticky tape. Two types of applicators were used and compared: a fine-tipped spatula and a foam-tipped applicator. The sticky tape was on a standard SEM “tee” mount, which was tapped to remove loose contamination before being inserted into the SEM.« less

Growth and photocatalytic properties of Sb-doped ZnO nanoneedles by hydrothermal process

NASA Astrophysics Data System (ADS)

Abaker, M.; Umar, Ahmad; Al-Sayari, S. A.; Dar, G. N.; Faisal, M.; Kim, S. H.; Hwang, S. W.

2011-10-01

This paper reports a facile hydrothermal synthesis of Sb-doped ZnO nanoneedles by using aqueous mixtures of zinc chloride, antimony (Sb) chloride, hexamethylenetetramine (HMTA) and ammonium hydroxide at low temperature of 110 °C. The morphological characterizations of as-synthesized nanoneedles were done by field emission scanning electron microscopy (FESEM) which reveals that the nanoneedles are grown in large-quantity and arranged in such a special manner that they made flower-like morphologies. The structural characterization of as-synthesized nanoneedles was investigated by X-ray diffraction (XRD) pattern which confirm the well-crystalline and wurtzite hexagonal phase of as-synthesized products. The compositional characterization of as-synthesized nanoneedles was characterized by energy dispersive spectroscopy (EDS), which verify that the synthesized nanoneedles are composed of zinc, Sb and oxygen. For application point of view, the synthesized nanoneedles were used as photocatalyst for photocatalytic degradation of methylene blue (MBB) and it was found that it exhibit good photocatalytic properties towards the photocatalytic degradation of methylene blue.

Cyclic oxidation behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere coating

NASA Astrophysics Data System (ADS)

Mathapati, Mahantayya; Ramesh M., R.; Doddamani, Mrityunjay

2018-04-01

Components working at elevated temperature like boiler tubes of coal and gas fired power generation plants, blades of gas and steam turbines etc. experience degradation owing to oxidation. Oxidation resistance of such components can be increased by developing protective coatings. In the present investigation NiCrAlY-WC-Co/Cenosphere coating is deposited on MDN 321 steel substrate using plasma spray coating. Thermo cyclic oxidation behavior of coating and substrate is studied in static air at 600 °C for 20 cycles. The thermo gravimetric technique is used to approximate the kinetics of oxidation. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray mapping techniques are used to characterize the oxidized samples. NiCrAlY-WC-Co/Cenosphere coating exhibited lower oxidation rate in comparison to MDN 321 steel substrate. The lower oxidation rate of coating is attributed to formation of Al2O3, Cr2O3, NiO and CoWO4 oxides on the outermost surface.

Manufacturing and characterization of Ni-free N-containing ODS austenitic alloy

NASA Astrophysics Data System (ADS)

Mori, A.; Mamiya, H.; Ohnuma, M.; Ilavsky, J.; Ohishi, K.; Woźniak, Jarosław; Olszyna, A.; Watanabe, N.; Suzuki, J.; Kitazawa, H.; Lewandowska, M.

2018-04-01

Ni-free N-containing oxide dispersion strengthened (ODS) austenitic alloys were manufactured by mechanical alloying (MA) followed by spark plasma sintering (SPS). The phase evolutions during milling under a nitrogen atmosphere and after sintering were studied by X-ray diffraction (XRD). Transmission electron microcopy (TEM) and alloy contrast variation analysis (ACV), including small-angle neutron scattering (SANS) and ultra-small-angle X-ray scattering (USAXS), revealed the existence of nanoparticles with a diameter of 3-51 nm for the samples sintered at 950 °C. Sintering at 1000 °C for 5 and 15 min caused slight growth and a significant coarsening of the nanoparticles, up to 70 nm and 128 nm, respectively. The ACV analysis indicated the existence of two populations of Y2O3, ε-martensite and MnO. The dispersive X-ray spectrometry (EDS) confirmed two kinds of nanoparticles, Y2O3 and MnO. The material was characterized by superior micro-hardness, of above 500 HV0.1.

Durable flame retardant and antibacterial finishing on cotton fabrics with cyclotriphosphazene/polydopamine/silver nanoparticles hybrid coatings

NASA Astrophysics Data System (ADS)

Li, Yingzhan; Wang, Bijia; Sui, Xiaofeng; Xie, Ruyi; Xu, Hong; Zhang, Linping; Zhong, Yi; Mao, Zhiping

2018-03-01

Durable flame retardant and antibacterial hybrid coatings were developed for cotton fabrics via simultaneous polymerization of dopamine and hydrolytic condensation of N3P3[NH(CH2)3Si(OC2H5)3]6. Silver nanoparticles were also introduced to the coatings by in situ reaction of AgNO3 with catechol moieties on polydopamine (PDA) in the absence of any external reducing agents. Energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were employed to study the morphology and constitution of the coatings. Thermal stability and combustion behaviors were characterized with thermogravimetric analysis (TGA) and vertical flammability tests. Considerable flame retardancy was obtained for the modified cotton fabrics, which also exhibited decent antibacterial activities (99.99%) against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. The modification was durable with largely intact flame retardancy and antimicrobial properties after 30 washing cycles.

Manufacturing and characterization of Ni-free N-containing ODS austenitic alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kowalska-Mori, A.; Mamiya, H.; Ohnuma, M.

Ni-free N-containing oxide dispersion strengthened (ODS) austenitic alloys were manufactured by mechanical alloying (MA) followed by spark plasma sintering (SPS). The phase evolutions during milling under a nitrogen atmosphere and after sintering were studied by X-ray diffraction (XRD). Transmission electron microcopy (TEM) and contrast variation analysis (ACV), including small-angle neutron scattering (SANS) and ultra-small X-ray scattering (USAXS), revealed the existence of nanoparticles with a diameter of 3-51 nm for the samples sintered at 950 ºC. Sintering at 1000 ºC for 5 and 15 min caused slight growth and a significant coarsening of the nanoparticles, up to 70 nm and 128more » nm, respectively. The ACV analysis indicated the existence of two populations of Y2O3, ε-martensite and MnO. The dispersive X-ray spectrometry (EDS) confirmed two kinds of nanoparticles, Y2O3 and MnO. The material was characterized by superior micro-hardness, of above 500 HV0.1.« less

Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

NASA Astrophysics Data System (ADS)

Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

2012-01-01

High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.

Chemical characteristics and leachability of organically contaminated heavy metal sludge solidified by silica fume and cement.

PubMed

Jun, K S; Hwang, B G; Shin, H S; Won, Y S

2001-01-01

This paper discusses the development of mixtures with silica fume as a stabilization/solidification agent and binder for industrial wastewater residue containing organic and heavy metal contaminants. The UCS (Unconfined Compressive Strength) gradually increased to 66.7% as the silica fume content increased to 15%. The leaching of TOC and chromium decreased as more OPC was substituted with silica fume. When the mix had 5% silica fume, it retained about 85% TOC, and chromium leached out 0.76 mg-Cr/g-Cr in acidic solution. Also, microstructural studies on the solidified wastes through the scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction analysis showed that the silica fume caused an inhibition to the ettringite formation which did not contribute to setting, but coated the cement particles and retarded the setting reactions. The results indicated that the incorporation of silica fume into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction and contaminant leachability.

Synthesis and Characterization of Highly Intercalated Graphite Bisulfate

NASA Astrophysics Data System (ADS)

Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

2017-03-01

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy ( μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO4, K2Cr2O7) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO4 and NaClO3.

Photocatalytic activity of Fe-doped CaTiO₃ under UV-visible light.

PubMed

Yang, He; Han, Chong; Xue, Xiangxin

2014-07-01

The photocatalytic degradation of methylene blue (MB) over Fe-doped CaTiO₃ under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) system, Fourier transform infrared spectra (FT-IR), and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO₃ in the visible light region. The Fe-doped CaTiO₃ exhibited higher photocatalytic activity than CaTiO₃ for the degradation of MB. However, the photocatalytic activity of the Fe-doped CaTiO₃ was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO₃ prepared at 500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB (10ppm) under UV-visible light for 180 min. Copyright © 2014. Published by Elsevier B.V.

Effects of metal binder on the microstructure and mechanical properties of Al2O3-based micro-nanocomposite ceramic tool material

NASA Astrophysics Data System (ADS)

Ni, Xiu-ying; Zhao, Jun; Sun, Jia-lin; Gong, Feng; Li, Zuo-li

2017-07-01

The Al2O3-(W,Ti)C composites with Ni and Mo additions varying from 0vol% to 12vol% were prepared via hot pressing sintering under 30 MPa. The microstructure was investigated via X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Mechanical properties such as flexural strength, fracture toughness, and Vickers hardness were also measured. Results show that the main phases A12O3 and (W,Ti)C were detected by XRD. Compound MoNi also existed in sintered nanocomposites. The fracture modes of the nanocomposites were both intergranular and transgranular fractures. The plastic deformation of metal particles and crack bridging were the main toughening mechanisms. The maximum flexural strength and fracture toughness were obtained for 9vol% and 12vol% additions of Ni and Mo, respectively. The hardness of the composites reduced gradually with increasing content of metals Ni and Mo.

Fabrication and characterization of nano-gas sensor arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassan, H. S., E-mail: hassan.shokry@gmail.com; Kashyout, A. B., E-mail: hady8@yahoo.com; Morsi, I., E-mail: drimanmorsi@yahoo.com

2015-03-30

A novel structures of Nanomaterials gas sensors array constructed using ZnO, and ZnO doped with Al via sol-gel technique. Two structure arrays are developed; the first one is a double sensor array based on doping with percentages of 1% and 5%. The second is a quadrature sensor array based on several doping ratios concentrations (0%, 1%, 5% and 10%). The morphological structures of prepared ZnO were revealed using scanning electron microscope (SEM). X-ray diffraction (XRD) patterns reveal a highly crystallized wurtzite structure and used for identifying phase structure and chemical state of both ZnO and ZnO doped with Al undermore » different preparation conditions and different doping ratios. Chemical composition of Al-doped ZnO nanopowders was performed using energy dispersive x-ray (EDS) analysis. The electrical characteristics of the sensor are determined by measuring the two terminal sensor’s output resistance for O{sub 2}, H{sub 2} and CO{sub 2} gases as a function of temperature.« less

Room-temperature H2S Gas Sensor Based on Au-doped ZnFe2O4 Yolk-shell Microspheres.

PubMed

Yan, Yin; Nizamidin, Patima; Turdi, Gulmira; Kari, Nuerguli; Yimit, Abliz

2017-01-01

Room-temperature type H 2 S sensing devices that use Au-doped ZnFe 2 O 4 yolk-shell microspheres as the active material have been fabricated using a solvothermal method as well as subsequent annealing and a chemical etching process. The samples are characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the doping of Au does not change the spinel structure of the products, which were yolk-shell microspheres, while the particle size varied with the Au doping concentration. Also, the as-fabricated sensor device exhibited excellent selectivity toward H 2 S gas at the room temperature; the gas-sensing property of 2 wt% Au-doped ZnFe 2 O 4 microspheres was the best. The Au-doped ZnFe 2 O 4 yolk-shell microspheres can be promising as a sensing material for H 2 S gas detecting at room temperature.

Compressive Properties of Open-Cell Al Hybrid Foams at Different Temperatures

PubMed Central

Liu, Jiaan; Si, Fujian; Zhu, Xianyong; Liu, Yaohui; Zhang, Jiawei; Liu, Yan; Zhang, Chengchun

2017-01-01

Hybrid Ni/Al foams were fabricated by depositing electroless Ni–P (EN) coatings on open-cell Al foam substrate to obtain enhanced mechanical properties. The microstructure, chemical components and phases of the hybrid foams were observed and analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The mechanical properties of the foams were studied by compressive tests at different temperatures. The experiment results show that the coating is mainly composed of Ni and P elements. There was neither defect at the interface nor crack in the coatings, indicating that the EN coatings had fine adhesion to the Al substrate. The compressive strengths and energy absorption capacities of the as-received foam and hybrid foams decrease with the increasing testing temperatures, but the hybrid foams exhibit a lower decrement rate than the as-received foam. This might be attributed to the different failure mechanisms at different testing temperatures, which is conformed by fractography observation. PMID:28772456

Manufacturing and characterization of Ni-free N-containing ODS austenitic alloys

DOE PAGES

Kowalska-Mori, A.; Mamiya, H.; Ohnuma, M.; ...

2018-01-17

Ni-free N-containing oxide dispersion strengthened (ODS) austenitic alloys were manufactured by mechanical alloying (MA) followed by spark plasma sintering (SPS). The phase evolutions during milling under a nitrogen atmosphere and after sintering were studied by X-ray diffraction (XRD). Transmission electron microcopy (TEM) and contrast variation analysis (ACV), including small-angle neutron scattering (SANS) and ultra-small X-ray scattering (USAXS), revealed the existence of nanoparticles with a diameter of 3-51 nm for the samples sintered at 950 ºC. Sintering at 1000 ºC for 5 and 15 min caused slight growth and a significant coarsening of the nanoparticles, up to 70 nm and 128more » nm, respectively. The ACV analysis indicated the existence of two populations of Y2O3, ε-martensite and MnO. The dispersive X-ray spectrometry (EDS) confirmed two kinds of nanoparticles, Y2O3 and MnO. The material was characterized by superior micro-hardness, of above 500 HV0.1.« less

Microstructural and Microanalytical Study on Concrete Exposed to the Sulfate Environment

NASA Astrophysics Data System (ADS)

Qing, Fang; Beixing, Li; Jiangang, Yin; Xiaolu, Yuan

2017-11-01

Microstructural properties have been examined to investigate the effect of mineral admixtures on the sulfate resistance of concrete. Concrete and cement paste specimens made with ordinary Portland cement (OPC) or ordinary Portland cement incorporating 20% fly ash (FA) or 30% ground blast furnace slag (GBFS), were made and exposed to 250 cycles of the cyclic sulfate environment. Microstructural and Microanalytical study was conducted by means of x-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and mercury intrusion porosimetry (MIP). Results indicate that the pore structure of concrete after sulfate exposure possesses the fractal feature. The OPC concrete presents more complex pore internal surface, higher porosity and less micro-pores than the concrete incorporating fly ash and GBFS. Portlandite in OPC concrete and OPC-FA concrete is mainly converted to gypsum; while for OPC-GBFS concrete, both gypsum and ettringite are formed. In the cyclic sulfate environment, repeated hydration and dehydration of sulfates produce the expansive stress in pores, aggravating the demolishment of concrete structure.

Synthesis, structural and optical properties of PVP coated transition metal doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Desai, N. V.; Shaikh, I. A.; Rawal, K. G.; Shah, D. V.

2018-05-01

The room temperature photoluminescence (PL) of transition metal doped ZnS nanoparticles is investigated in the present study. The PVP coated ZnS nanoparticles doped with transition metals are synthesized by facile wet chemical co-precipitation method with the concentration of impurity 1%. The UV-Vis absorbance spectra have a peak at 324nm which shifts slightly to 321nm upon introduction of the impurity. The incorporation of the transition metal as dopant is confirmed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The particle size and the morphology are characterized by scanning electron microscopy (SEM), XRD and UV-Vis spectroscopy. The average size of synthesized nanoparticles is about 2.6nm. The room temperature photoluminescence (PL) of undoped and doped ZnS nanoparticles show a strong and sharp peak at 782nm and 781.6nm respectively. The intensity of the PL changes with the type of doping having maximum for manganese (Mn).

Synthesis and Characterization of Highly Intercalated Graphite Bisulfate.

PubMed

Salvatore, Marcella; Carotenuto, Gianfranco; De Nicola, Sergio; Camerlingo, Carlo; Ambrogi, Veronica; Carfagna, Cosimo

2017-12-01

Different chemical formulations for the synthesis of highly intercalated graphite bisulfate have been tested. In particular, nitric acid, potassium nitrate, potassium dichromate, potassium permanganate, sodium periodate, sodium chlorate, and hydrogen peroxide have been used in this synthesis scheme as the auxiliary reagent (oxidizing agent). In order to evaluate the presence of delamination, and pre-expansion phenomena, and the achieved intercalation degree in the prepared samples, the obtained graphite intercalation compounds have been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), micro-Raman spectroscopy (μ-RS), and thermal analysis (TGA). Delamination and pre-expansion phenomena were observed only for nitric acid, sodium chlorate, and hydrogen peroxide, while the presence of strong oxidizers (KMnO 4 , K 2 Cr 2 O 7 ) led to stable graphite intercalation compounds. The largest content of intercalated bisulfate is achieved in the intercalated compounds obtained from NaIO 4 and NaClO 3 .

Plasma surface tantalum alloying on titanium and its corrosion behavior in sulfuric acid and hydrochloric acid

NASA Astrophysics Data System (ADS)

Wei, D. B.; Chen, X. H.; Zhang, P. Z.; Ding, F.; Li, F. K.; Yao, Z. J.

2018-05-01

An anti-corrosion Ti-Ta alloy coating was prepared on pure titanium surface by double glow plasma surface alloying technology. Electrochemical corrosion test was applied to test the anti-corrosion property of Ti-Ta alloy layer. The microstructure and the phase composition of Ti-Ta alloy coating were detected before and after corrosion process by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The results showed that the Ta-Ti alloy layer has a thickness of about 13-15 μm, which is very dense without obvious defects such as pores or cracks. The alloy layer is composed mainly of β-Ta and α-Ti. The Ta alloy layer improves the anti-corrosion property of pure titanium. A denser and more durable TiO2 formed on the surface Ta-Ti alloy layer after immersing in strong corrosive media may account for the excellent corrosion resistant.

Surface laser alloying of 17-4PH stainless steel steam turbine blades

NASA Astrophysics Data System (ADS)

Yao, Jianhua; Wang, Liang; Zhang, Qunli; Kong, Fanzhi; Lou, Chenghua; Chen, Zhijun

2008-09-01

As a known high-quality precipitation hardening stainless steel with high strength, high antifatigue, excellent corrosion resistance and good weldability, 17-4PH has been widely used to produce steam turbine blades. However, under the impact of high-speed steam and water droplets, the blades are prone to cavitation, which could lead to lower efficiency, shorter life time, and even accidents. In this article, the 17-4PH blade's surface was alloyed using a high power CO 2 laser. The microstructure and microhardness of hardened 17-4PH were tested by scanning electronic microscope (SEM), X-ray diffraction (XRD), energy disperse spectroscopy (EDS) and a microhardness tester. After laser alloying, the surface layer was denser and the grain refined, while the microhardness of the surface (average 610HV 0.2) was about one times higher than that of the substrate material (330HV 0.2). The friction coefficient of the laser-alloyed 17-4PH layer was much lower than that of the substrate.

Evaluation of White Bentonite Modified by Acid Attack

NASA Astrophysics Data System (ADS)

Andrade, C. G. Bastos; Fermino, D. M.; Fernandes, M. G.; Valenzuela-Diaz, F. R.

For industrial use, the smectite clays must be cleared of impurities, usually obtained by acid modification, using a high concentration solution of inorganic acid at temperatures under boiling point. In the present paper, a sample of white bentonite from Paraiba, Brazil, was modified by hydrochloric acid under moderate conditions (90°C, reaction times of 1, 6, 12, 18 and 24hours in close reactor, concentration of the aqueous solution of hydrochloric acid 1.5 M, acid solution/clay ratio of 1g/10mL). The purpose of these attacks is to reduce the concentration of impurities with minimal change in the clay minerals structure. The modified samples were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Cation Exchange Capacity (CEC), Stereomicroscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Detector (EDS). Thus, this modified bentonite tends to be a good economic and environmental alternative in manufacturing of products with high added value such as cosmetics and polymer/clay nanocomposites.

The Corrosion Behavior of Pure Iron under Solid Na₂SO₄ Deposit in Wet Oxygen Flow at 500 °C.

PubMed

Tang, Yanbing; Liu, Li; Fan, Lei; Li, Ying; Wang, Fuhui

2014-08-27

The corrosion behavior of pure Fe under a Na₂SO₄ deposit in an atmosphere of O₂ + H₂O was investigated at 500 °C by thermo gravimetric, and electrochemical measurements, viz . potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and surface characterization methods viz . X-ray diffraction (XRD), and scanning electron microscope (SEM)/energy dispersive spectroscopy(EDS). The results showed that a synergistic effect occurred between Na₂SO₄ and O₂ + H₂O, which significantly accelerated the corrosion rate of the pure Fe. Briefly, NaFeO₂ was formed in addition to the customary Fe oxides; at the same time, H₂SO₄ gas was produced by introduction of water vapor. Subsequently, an electrochemical corrosion reaction occurred due to the existence of Na₂SO₄, NaFeO₂, and H₂O. When this coupled to the chemical corrosion reaction, the progress of the chemical corrosion reaction was promoted and eventually resulted in the acceleration of the corrosion of the pure Fe.

Bimetal-organic frameworks for functionality optimization: MnFe-MOF-74 as a stable and efficient catalyst for the epoxidation of alkenes with H2O2.

PubMed

Yuan, Kuo; Song, Tianqun; Wang, Dawei; Zou, Ye; Li, Jinfeng; Zhang, Xiaotao; Tang, Zhiyong; Hu, Wenping

2018-01-25

In this work, we synthesized a series of microcrystalline Mn x N 100-x -MOF-74 (N = Fe, Co and Ni) materials by a one-pot reaction. Powder X-ray diffraction (PXRD) patterns of Mn x N 100-x -MOF-74 matched well with those of single-metal MOF-74, and the scanning electron microscopy (SEM) images exhibited homogeneous nanocrystallites aggregated together. The amounts and dispersion of metals were analyzed by using inductively coupled plasma (ICP) and energy-dispersive X-ray spectroscopy (EDS), separately. Mn x N 100-x -MOF-74 could remain crystalline and efficiently catalyze the epoxidation of alkenes in DMF with NaHCO 3 and 30% H 2 O 2 . In particular, Mn 29.39 Fe 70.61 -MOF-74 can achieve almost 100% conversion for styrene with 95.0% selectivity towards styrene oxide and be reused at least five times without loss of activity.

Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Chun-Yueh; Chang, Wei-Tse; Chen, Yi-Sheng

2016-03-15

In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This workmore » demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.« less

Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

PubMed Central

He, Z.-H.; Beaurepaire, B.; Nees, J. A.; Gallé, G.; Scott, S. A.; Pérez, J. R. Sánchez; Lagally, M. G.; Krushelnick, K.; Thomas, A. G. R.; Faure, J.

2016-01-01

Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scale by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes. PMID:27824086

Capturing Structural Dynamics in Crystalline Silicon Using Chirped Electrons from a Laser Wakefield Accelerator

DOE PAGES

He, Z. -H.; Beaurepaire, B.; Nees, J. A.; ...

2016-11-08

Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have enormous benefits for ultrafast science. These novel sources promise to become indispensable tools for the investigation of structural dynamics on the femtosecond time scale, with spatial resolution on the atomic scale. Here in this paper, we demonstrate the use of laser-wakefield-accelerated electron bunches for time-resolved electron diffraction measurements of the structural dynamics of single-crystal silicon nano-membranes pumped by an ultrafast laser pulse. In our proof-of-concept study, we resolve the silicon lattice dynamics on a picosecond time scalemore » by deflecting the momentum-time correlated electrons in the diffraction peaks with a static magnetic field to obtain the time-dependent diffraction efficiency. Further improvements may lead to femtosecond temporal resolution, with negligible pump-probe jitter being possible with future laser-wakefield-accelerator ultrafast-electron-diffraction schemes.« less

The significance of Bragg's law in electron diffraction and microscopy, and Bragg's second law.

PubMed

Humphreys, C J

2013-01-01

Bragg's second law, which deserves to be more widely known, is recounted. The significance of Bragg's law in electron diffraction and microscopy is then discussed, with particular emphasis on differences between X-ray and electron diffraction. As an example of such differences, the critical voltage effect in electron diffraction is described. It is then shown that the lattice imaging of crystals in high-resolution electron microscopy directly reveals the Bragg planes used for the imaging process, exactly as visualized by Bragg in his real-space law. Finally, it is shown how in 2012, for the first time, on the centennial anniversary of Bragg's law, single atoms have been identified in an electron microscope using X-rays emitted from the specimen. Hence atomic resolution X-ray maps of a crystal in real space can be formed which give the positions and identities of the different atoms in the crystal, or of a single impurity atom in the crystal.

Accuracy of automatic syndromic classification of coded emergency department diagnoses in identifying mental health-related presentations for public health surveillance.

PubMed

Liljeqvist, Henning T G; Muscatello, David; Sara, Grant; Dinh, Michael; Lawrence, Glenda L

2014-09-23

Syndromic surveillance in emergency departments (EDs) may be used to deliver early warnings of increases in disease activity, to provide situational awareness during events of public health significance, to supplement other information on trends in acute disease and injury, and to support the development and monitoring of prevention or response strategies. Changes in mental health related ED presentations may be relevant to these goals, provided they can be identified accurately and efficiently. This study aimed to measure the accuracy of using diagnostic codes in electronic ED presentation records to identify mental health-related visits. We selected a random sample of 500 records from a total of 1,815,588 ED electronic presentation records from 59 NSW public hospitals during 2010. ED diagnoses were recorded using any of ICD-9, ICD-10 or SNOMED CT classifications. Three clinicians, blinded to the automatically generated syndromic grouping and each other's classification, reviewed the triage notes and classified each of the 500 visits as mental health-related or not. A "mental health problem presentation" for the purposes of this study was defined as any ED presentation where either a mental disorder or a mental health problem was the reason for the ED visit. The combined clinicians' assessment of the records was used as reference standard to measure the sensitivity, specificity, and positive and negative predictive values of the automatic classification of coded emergency department diagnoses. Agreement between the reference standard and the automated coded classification was estimated using the Kappa statistic. Agreement between clinician's classification and automated coded classification was substantial (Kappa = 0.73. 95% CI: 0.58 - 0.87). The automatic syndromic grouping of coded ED diagnoses for mental health-related visits was found to be moderately sensitive (68% 95% CI: 46%-84%) and highly specific at 99% (95% CI: 98%-99.7%) when compared with the reference standard in identifying mental health related ED visits. Positive predictive value was 81% (95% CI: 0.57 - 0.94) and negative predictive value was 98% (95% CI: 0.97-0.99). Mental health presentations identified using diagnoses coded with various classifications in electronic ED presentation records offers sufficient accuracy for application in near real-time syndromic surveillance.

Quasi-parallel precession diffraction: Alignment method for scanning transmission electron microscopes.

PubMed

Plana-Ruiz, S; Portillo, J; Estradé, S; Peiró, F; Kolb, Ute; Nicolopoulos, S

2018-06-06

A general method to set illuminating conditions for selectable beam convergence and probe size is presented in this work for Transmission Electron Microscopes (TEM) fitted with µs/pixel fast beam scanning control, (S)TEM, and an annular dark field detector. The case of interest of beam convergence and probe size, which enables diffraction pattern indexation, is then used as a starting point in this work to add 100 Hz precession to the beam while imaging the specimen at a fast rate and keeping the projector system in diffraction mode. The described systematic alignment method for the adjustment of beam precession on the specimen plane while scanning at fast rates is mainly based on the sharpness of the precessed STEM image. The complete alignment method for parallel condition and precession, Quasi-Parallel PED-STEM, is presented in block diagram scheme, as it has been tested on a variety of instruments. The immediate application of this methodology is that it renders the TEM column ready for the acquisition of Precessed Electron Diffraction Tomographies (EDT) as well as for the acquisition of slow Precessed Scanning Nanometer Electron Diffraction (SNED). Examples of the quality of the Precessed Electron Diffraction (PED) patterns and PED-STEM alignment images are presented with corresponding probe sizes and convergence angles. Copyright © 2018. Published by Elsevier B.V.

Comments on the paper "Bragg's law diffraction simulations for electron backscatter diffraction analysis" by Josh Kacher, Colin Landon, Brent L. Adams & David Fullwood.

PubMed

Maurice, Claire; Fortunier, Roland; Driver, Julian; Day, Austin; Mingard, Ken; Meaden, Graham

2010-06-01

This comment on the paper "Bragg's Law diffraction simulations for electron backscatter diffraction analysis" by Kacher et al. explains the limitations in determining elastic strains using synthetic EBSD patterns. Of particular importance are those due to the accuracy of determination of the EBSD geometry projection parameters. Additional references and supporting information are provided. Copyright 2010 Elsevier B.V. All rights reserved.

Field-Effect Spectroscopy of Interface States

DTIC Science & Technology

1988-12-31

ed.), Physics and Chemistry of Il-V Compound Semiconductor Interfaces, Plenum, New York, 1985, p. 327. HETEROJUNCTION AND DIELECTRICALLY INSULATED GATE...Electron Devices. voi. ED-29. pp. 1059-1064, 1982. chemistry , and physics from San Diego State Uni- 131 T. H. Mies, W. M. Paulson, and M. S...1982). 40. T. Y. Chang, R. F. Leheny, R. E. Nahory, E. Silberg , A. A. Ballman, E. A. Carid’ and C. J. Harrold, IEEE Electron. Dev. Lett. EDL- 3, 56

Anomalous Diffraction in Crystallographic Phase Evaluation

PubMed Central

Hendrickson, Wayne A.

2014-01-01

X-ray diffraction patterns from crystals of biological macromolecules contain sufficient information to define atomic structures, but atomic positions are inextricable without having electron-density images. Diffraction measurements provide amplitudes, but the computation of electron density also requires phases for the diffracted waves. The resonance phenomenon known as anomalous scattering offers a powerful solution to this phase problem. Exploiting scattering resonances from diverse elements, the methods of multiwavelength anomalous diffraction (MAD) and single-wavelength anomalous diffraction (SAD) now predominate for de novo determinations of atomic-level biological structures. This review describes the physical underpinnings of anomalous diffraction methods, the evolution of these methods to their current maturity, the elements, procedures and instrumentation used for effective implementation, and the realm of applications. PMID:24726017

Nature and origin of interstellar diamond from the Allende CV3 meteorite

NASA Technical Reports Server (NTRS)

Blake, David; Freund, Friedemann; Bunch, Ted; Krishnan, Kannan; Stampfer, Mitch; Chang, Sherwood; Tielens, Alexander G. G. M.

1990-01-01

Data and experimental evidence which support the contention that the C delta diamonds may result from grain-grain collisions in supernova shocks in the interstellar medium are presented. Fragments of the Allende CV3 chondrite were acid-treated. A whitish powder was obtained. For the Analytical Electron Microscopy (AEM) a small drop of ethanol suspension was transferred onto holey carbon support films on 3 mm EM grids. The AEM was performed on transmission-thin fragments of the material which overlay holes in the film, to eliminate interference from the substrate. Electron Spectroscopy for Chemical Analysis (ESCA) was performed on a large aliquot of C. Diamond was identified by selected area electron diffraction. Scanning Transmission Electron Microscope / Energy Dispersive X-ray (STEM-EDS) microanalyses of the C delta diamond, using a light-element detector, show that oxygen and possibly nitrogen are the only impurities consistently present. ESCA spectra from bulk C delta material confirm the presence of N at a level of 0.35 percent or less. Under UV irradiation a yellow-red fluorescence is observed, consistent with that of natural diamonds containing substitutional N. Electron Energy Loss Spectra (EELS) were recorded at 2 eV resolution from the C delta diamond, high pressure synthetic diamond, a diamond film produced in a low pressure plasma by chemical vapor deposition (CVD) on a heated silicon substrate (Roy, 1987), graphite, and amorphous arc sputtered carbon. Comparison of the carbon K edge shape and fine structure shows the Allende C delta phase to be largely diamond, but with a significant pre-edge absorption feature indicative of transitions of C 1s electrons into pi asterisk orbitals which are absent in the purely sp(3)-bonded diamond but present in graphite and amorphous carbon.

Structures of Astromaterials Revealed by EBSD

NASA Technical Reports Server (NTRS)

Zolensky, M.

2018-01-01

Groups at the Johnson Space Center and the University of Tokyo have been using electron back-scattered diffraction (EBSD) to reveal the crystal structures of extraterrestrial minerals for many years. Even though we also routinely use transmission electron microscopy, synchrotron X-ray diffraction (SXRD), and conventional electron diffraction, we find that EBSD is the most powerful technique for crystal structure elucidation in many instances. In this talk I describe a few of the cases where we have found EBSD to provide crucial, unique information. See attachment.

Serial single molecule electron diffraction imaging: diffraction background of superfluid helium droplets

NASA Astrophysics Data System (ADS)

Zhang, Jie; He, Yunteng; Lei, Lei; Alghamdi, Maha; Oswalt, Andrew; Kong, Wei

2017-08-01

In an effort to solve the crystallization problem in crystallography, we have been engaged in developing a method termed "serial single molecule electron diffraction imaging" (SS-EDI). The unique features of SS-EDI are superfluid helium droplet cooling and field-induced orientation: together the two features constitute a molecular goniometer. Unfortunately, the helium atoms surrounding the sample molecule also contribute to a diffraction background. In this report, we analyze the properties of a superfluid helium droplet beam and its doping statistics, and demonstrate the feasibility of overcoming the background issue by using the velocity slip phenomenon of a pulsed droplet beam. Electron diffraction profiles and pair correlation functions of ferrocene-monomer-doped droplets and iodine-nanocluster-doped droplets are presented. The timing of the pulsed electron gun and the effective doping efficiency under different dopant pressures can both be controlled for size selection. This work clears any doubt of the effectiveness of superfluid helium droplets in SS-EDI, thereby advancing the effort in demonstrating the "proof-of-concept" one step further.

Molecular structures and intramolecular dynamics of pentahalides

NASA Astrophysics Data System (ADS)

Ischenko, A. A.

2017-03-01

This paper reviews advances of modern gas electron diffraction (GED) method combined with high-resolution spectroscopy and quantum chemical calculations in studies of the impact of intramolecular dynamics in free molecules of pentahalides. Some recently developed approaches to the electron diffraction data interpretation, based on direct incorporation of the adiabatic potential energy surface parameters to the diffraction intensity are described. In this way, complementary data of different experimental and computational methods can be directly combined for solving problems of the molecular structure and its dynamics. The possibility to evaluate some important parameters of the adiabatic potential energy surface - barriers to pseudorotation and saddle point of intermediate configuration from diffraction intensities in solving the inverse GED problem is demonstrated on several examples. With increasing accuracy of the electron diffraction intensities and the development of the theoretical background of electron scattering and data interpretation, it has become possible to investigate complex nuclear dynamics in fluxional systems by the GED method. Results of other research groups are also included in the discussion.

Implementing an Internet-based communication network for use during skilled nursing facility to emergency department care transitions: challenges and opportunities for improvement.

PubMed

Hustey, Fredric M; Palmer, Robert M

2012-03-01

To explore the feasibility of implementing an Internet-based communication network for communication of health care information during skilled nursing facility (SNF)-to-ED care transitions, and to identify potential barriers to system implementation. Qualitative. The largest SNF affiliated with the ED of an urban tertiary care center. Consecutive sample of all patients transferred from SNF to ED over 8 months between June 2007 and January 2008; ED and SNF care providers. The development and implementation of an Internet-based communication network for use during SNF-to-ED care transitions. This network was developed by adapting a preexisting Internet-based system that is widely used to facilitate placement of hospitalized patients into SNFs. Internet-based SNF and ED surveys were used to help identify barriers to implementation. There were 276/276 care transitions reviewed. The Internet-based communication network was used in 76 (28%) care transitions, with usage peaking at 40% near the end of the study. Barriers to success that were identified included lack of an electronic medical record (EMR) at the SNF; pervasive negative attitudes between ED and SNF personnel; time necessary for network use during care transitions; frustration by emergency physicians at low system usage rates by SNF personnel; and additional login requirements by ED personnel. Although implementing an Internet-based network for nursing home to ED communication may be feasible, significant barriers were identified in this study that are likely generalizable to other health care settings. Understanding such barriers is an essential first step toward building successful electronic communication networks in the future. Copyright © 2012 American Medical Directors Association, Inc. Published by Elsevier Inc. All rights reserved.

Microstructure and mineral composition of dental enamel of permanent and deciduous teeth.

PubMed

De Menezes Oliveira, Maria Angélica Hueb; Torres, Carolina Paes; Gomes-Silva, Jaciara Miranda; Chinelatti, Michelle Alexandra; De Menezes, Fernando Carlos Hueb; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

2010-05-01

This study evaluated and compared in vitro the microstructure and mineral composition of permanent and deciduous teeth's dental enamel. Sound third molars (n = 12) and second primary molars (n = 12) were selected and randomly assigned to the following groups, according to the analysis method performed (n = 4): Scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Energy dispersive X-ray spectrometer (EDS). Qualitative and quantitative comparisons of the dental enamel were done. The microscopic findings were analyzed statistically by a nonparametric test (Kruskal-Wallis). The measurements of the prisms number and thickness were done in SEM photomicrographs. The relative amounts of calcium (Ca) and phosphorus (P) were determined by EDS investigation. Chemical phases present in both types of teeth were observed by the XRD analysis. The mean thickness measurements observed in the deciduous teeth enamel was 1.14 mm and in the permanent teeth enamel was 2.58 mm. The mean rod head diameter in deciduous teeth was statistically similar to that of permanent teeth enamel, and a slightly decrease from the outer enamel surface to the region next to the enamel-dentine junction was assessed. The numerical density of enamel rods was higher in the deciduous teeth, mainly near EDJ, that showed statistically significant difference. The percentage of Ca and P was higher in the permanent teeth enamel. The primary enamel structure showed a lower level of Ca and P, thinner thickness and higher numerical density of rods. (c) 2009 Wiley-Liss, Inc.

Physicochemical analysis of urinary stones from Dharmapuri district

NASA Astrophysics Data System (ADS)

Aslin Shamema, A.; Thanigai Arul, K.; Senthil Kumar, R.; Narayana Kalkura, S.

2015-01-01

Nephrolithiasis is a common disease caused by the multifactorial components such as geographical location, bacterial infection, low urine volume, and low intake of water. This disease induces severe metabolic abnormalities in the human body. As the prevalence of this disease was high in Dharmapuri district located in Tamil Nadu, urinary stones removed from the patients pertaining to this district were collected and to identify the toxic elements present in the stones. The presence of functional groups and phases of the stones were analyzed using X-ray diffraction (XRD), Fourier transform Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The majority of stones were found to be calcium oxalate monohydrate (COM) and mixed stones having minor existence of struvite and uric acid. Hexagonal shaped COM crystals, needle shaped uric acid crystals and layered arrangement of struvite crystals in the core region were revealed by Scanning Electron Microscopy (SEM). Thermo Gravimetric Analysis (TGA) was used to determine the thermal stability and the hardness of the stone which was measured using Vickers hardness (HV). The presence of toxic elements in stones such as zirconium and mercury was identified using Energy Dispersive X-ray Spectroscopy (EDS). The EDS analysis showed higher concentration of zirconium in the core region compared to the periphery. The percentage of zirconium was relatively high compared to other toxic elements in the stones. The Vickers hardness results indicated that high HV values in the core region than the periphery and this might be due to the presence of zirconium.

Underground Habitats in the Río Tinto Basin: A Model for Subsurface Life Habitats on Mars

NASA Astrophysics Data System (ADS)

Fernández-Remolar, David C.; Prieto-Ballesteros, Olga; Rodríguez, Nuria; Gómez, Felipe; Amils, Ricardo; Gómez-Elvira, Javier; Stoker, Carol R.

2008-10-01

A search for evidence of cryptic life in the subsurface region of a fractured Paleozoic volcanosedimentary deposit near the source waters of the Río Tinto River (Iberian pyrite belt, southwest Spain) was carried out by Mars Astrobiology Research and Technology Experiment (MARTE) project investigators in 2003 and 2004. This conventional deep-drilling experiment is referred to as the MARTE ground truth drilling project. Boreholes were drilled at three sites, and samples from extracted cores were analyzed with light microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. Core leachates were analyzed with ion chromatography, and borehole fluids were analyzed with ion and gas chromatography. Key variables of the groundwater system (e.g. , pO2, pH, and salinity) exhibit huge ranges probably due to surficial oxygenation of overall reducing waters, physical mixing of waters, and biologically mediated water-rock interactions. Mineral distribution is mainly driven by the pH of subsurface solutions, which range from highly acidic to neutral. Borehole fluids contain dissolved gases such as CO2, CH4, and H2. SEM-EDS analyses of core samples revealed evidence of microbes attacking pyrite. The Río Tinto alteration mechanisms may be similar to subsurface weathering of the martian crust and provide insights into the possible (bio)geochemical cycles that may have accompanied underground habitats in extensive early Mars volcanic regions and associated sulfide ores.

Underground habitats in the Río Tinto basin: a model for subsurface life habitats on Mars.

PubMed

Fernández-Remolar, David C; Prieto-Ballesteros, Olga; Rodríguez, Nuria; Gómez, Felipe; Amils, Ricardo; Gómez-Elvira, Javier; Stoker, Carol R

2008-10-01

A search for evidence of cryptic life in the subsurface region of a fractured Paleozoic volcanosedimentary deposit near the source waters of the Río Tinto River (Iberian pyrite belt, southwest Spain) was carried out by Mars Astrobiology Research and Technology Experiment (MARTE) project investigators in 2003 and 2004. This conventional deep-drilling experiment is referred to as the MARTE ground truth drilling project. Boreholes were drilled at three sites, and samples from extracted cores were analyzed with light microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy. Core leachates were analyzed with ion chromatography, and borehole fluids were analyzed with ion and gas chromatography. Key variables of the groundwater system (e.g., pO(2), pH, and salinity) exhibit huge ranges probably due to surficial oxygenation of overall reducing waters, physical mixing of waters, and biologically mediated water-rock interactions. Mineral distribution is mainly driven by the pH of subsurface solutions, which range from highly acidic to neutral. Borehole fluids contain dissolved gases such as CO(2), CH(4), and H(2). SEM-EDS analyses of core samples revealed evidence of microbes attacking pyrite. The Río Tinto alteration mechanisms may be similar to subsurface weathering of the martian crust and provide insights into the possible (bio)geochemical cycles that may have accompanied underground habitats in extensive early Mars volcanic regions and associated sulfide ores.

Impedance spectroscopy of the oxide films formed during high temperature oxidation of a cobalt-plated ferritic alloy

NASA Astrophysics Data System (ADS)

Velraj, S.; Zhu, J. H.; Painter, A. S.; Du, S. W.; Li, Y. T.

2014-02-01

Impedance spectroscopy was used to evaluate the oxide films formed on cobalt-coated Crofer 22 APU ferritic stainless steel after thermal oxidation at 800 °C in air for different times (i.e. 2, 50, 100 and 500 h). Impedance spectra of the oxide films exhibited two or three semicircles depending on the oxidation time, which correspond to the presence of two or three individual oxide layers. Coupled with scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD), the individual oxide layer corresponding to each semicircle was determined unambiguously. Impedance spectrum analysis of the oxide films formed on the sample after thermal exposure at 800 °C in air for 2 h led to the identification of the low-frequency and high-frequency semicircles as being from Cr2O3 and Co3O4, respectively. SEM/EDS and XRD analysis of the 500-h sample clearly revealed the presence of three oxide layers, analyzed to be Co3-xCrxO4, CoCr2O4, and Cr2O3. Although the SEM images of the 50-h and 100-h samples did not clearly show the CoCr2O4 layer, impedance plots implied their presence. The oxide scales were assigned to their respective semicircles and the electrical properties of Co3-xCrxO4, CoCr2O4 and Cr2O3 were determined from the impedance data.

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

NASA Astrophysics Data System (ADS)

Ye, Qingfeng; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Li, Ruifeng; Huang, Jian; Wu, Yixiong

2017-02-01

Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower icorr than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted Rt value reaches its maximum at 24 h during a 48 h' immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H2SO4 reveals that corrosion starts from Cr-depleted interdendrites.

Characterization of biochar prepared from biogas digestate.

PubMed

Hung, Chao-Yi; Tsai, Wen-Tien; Chen, Jie-Wei; Lin, Yu-Quan; Chang, Yuan-Ming

2017-08-01

In the study, the biogas digestate was evaluated as a potential feedstock for preparing biochars at a broad temperature range of 300-900°C. The physico-chemical and pore properties of the resulting biochars (denoted as SDBC, solid digestate biochar), including calorific value (higher heating value), surface area/pore volume/pore size distribution, true density, scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD), were studied. It was found that the higher heating values of the SDBC products were on a decreasing trend as pyrolysis temperature increased, but they indicated an increase in true density. The results are probably associated with the active pyrolysis of the lignocellulosic fragments and the calcination (or shrinkage) processes, thus resulting in the increased contents of aromatic carbon clusters and main mineral constituents remained. Based on the pore properties, pyrolysis temperature at around 800°C seemed to be the optimal condition for producing SDBC, where its Brunauer-Emmet-Teller (BET) surface area (>100m 2 /g) largely increased as compared to that of the digestate feedstock (<1m 2 /g). Furthermore, the main compositions of mineral ash in the resulting biochar could exist as phosphates, carbonates, or oxides of calcium and other alkali/alkaline earth elements. According to the data on EDS and XRD, more pores could be significantly generated under severe pyrolysis (>700°C) due to the high aromaticity via the thermal decomposition of lignocelluloses and the volatilization of inorganic minerals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Progress and opportunities in EELS and EDS tomography.

PubMed

Collins, Sean M; Midgley, Paul A

2017-09-01

Electron tomography using energy loss and X-ray spectroscopy in the electron microscope continues to develop in rapidly evolving and diverse directions, enabling new insight into the three-dimensional chemistry and physics of nanoscale volumes. Progress has been made recently in improving reconstructions from EELS and EDS signals in electron tomography by applying compressed sensing methods, characterizing new detector technologies in detail, deriving improved models of signal generation, and exploring machine learning approaches to signal processing. These disparate threads can be brought together in a cohesive framework in terms of a model-based approach to analytical electron tomography. Models incorporate information on signal generation and detection as well as prior knowledge of structures in the spectrum image data. Many recent examples illustrate the flexibility of this approach and its feasibility for addressing challenges in non-linear or limited signals in EELS and EDS tomography. Further work in combining multiple imaging and spectroscopy modalities, developing synergistic data acquisition, processing, and reconstruction approaches, and improving the precision of quantitative spectroscopic tomography will expand the frontiers of spatial resolution, dose limits, and maximal information recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

Tuning Charge and Correlation Effects for a Single Molecule on a Graphene Device

NASA Astrophysics Data System (ADS)

Tsai, Hsin-Zon; Wickenburg, Sebastian; Lu, Jiong; Lischner, Johannes; Omrani, Arash A.; Riss, Alexander; Karrasch, Christoph; Jung, Han Sae; Khajeh, Ramin; Wong, Dillon; Watanabe, Kenji; Taniguchi, Takashi; Zettl, Alex; Louie, Steven G.; Crommie, Michael F.

Controlling electronic devices down to the single molecule level is a grand challenge of nanotechnology. Single-molecules have been integrated into devices capable of tuning electronic response, but a drawback for these systems is that their microscopic structure remains unknown due to inability to image molecules in the junction region. Here we present a combined STM and nc-AFM study demonstrating gate-tunable control of the charge state of individual F4TCNQ molecules at the surface of a graphene field effect transistor. This is different from previous studies in that the Fermi level of the substrate was continuously tuned across the molecular orbital energy level. Using STS we have determined the resulting energy level evolution of the LUMO, its associated vibronic modes, and the graphene Dirac point (ED). We show that the energy difference between ED and the LUMO increases as EF is moved away from ED due to electron-electron interactions that renormalize the molecular quasiparticle energy. This is attributed to gate-tunable image-charge screening in graphene and corroborated by ab initio calculations.

A conservative, relativistic Fokker-Planck solver for runaway electrons

NASA Astrophysics Data System (ADS)

Chacon, Luis; Taitano, W.; Tang, X.; Guo, Z.; McDevitt, C.

2017-10-01

Relativistic runaway electrons develop when electric fields surpass a critical electric field, Ec =EDvth/c 2 , with ED the Dreicer field (which is the electric field at which the whole thermal electron population runs away). Above this critical field, electron tails accelerate relativistically until they are arrested by radiative processes. In regimes above this critical electric field (but below the Dreicer field), correctly capturing the interplay between the electron thermal population and the runaway tail is key, and demands a full nonlinear relativistic Fokker-Planck treatment. In this presentation, we report on progress towards a fully conservative, implicit, adaptive implementation of the relativistic electron Fokker-Planck equation. Strict conservation properties, as well as positivity preservation, are a must to avoid spurious numerical effects, and to be able to capture tenuous electron runaway tails for fields just above Ec.

Working at the intersection of context, culture, and technology: Provider perspectives on antimicrobial stewardship in the emergency department using electronic health record clinical decision support.

PubMed

Chung, Phillip; Scandlyn, Jean; Dayan, Peter S; Mistry, Rakesh D

2017-11-01

Antibiotic stewardship programs (ASPs) have not been fully developed for the emergency department (ED), in part the result of the barriers characteristic of this setting. Electronic health record-based clinical decision support (EHR CDS) represents a promising strategy to implement ASPs in the ED. We aimed to determine the cultural beliefs and structural barriers and facilitators to implementation of antimicrobial stewardship in the pediatric ED using EHR CDS. Interviews and focus groups were conducted with hospital and ED leadership, attending ED physicians, nurse practitioners, physician assistants, and residents at a single health system in Colorado. We reviewed and coded the data using constant comparative analysis and framework analysis until a final set of themes emerged. Two dominant perceptions shaped providers' perspectives on ASPs in the ED and EHR CDS: (1) maintaining workflow efficiency and (2) constrained decision-making autonomy. Clinicians identified structural barriers to ASPs, such as pace of the ED, and various beliefs that shaped patterns of practice, including accommodating the prescribing decisions of other providers and managing parental expectations. Recommendations to enhance uptake focused on designing a simple yet flexible user interface, providing clinicians with performance data, and on-boarding clinicians to enhance buy-in. Developing a successful ED-based ASP using EHR CDS should attend to technologic needs, the institutional context, and the cultural beliefs of practice associated with providers' antibiotic prescribing. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Device and method for creating Gaussian aberration-corrected electron beams

DOEpatents

McMorran, Benjamin; Linck, Martin

2016-01-19

Electron beam phase gratings have phase profiles that produce a diffracted beam having a Gaussian or other selected intensity profile. Phase profiles can also be selected to correct or compensate electron lens aberrations. Typically, a low diffraction order produces a suitable phase profile, and other orders are discarded.

Breaking resolution limits in ultrafast electron diffraction and microscopy.

PubMed

Baum, Peter; Zewail, Ahmed H

2006-10-31

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100-200 keV for microscopy, corresponding to speeds of 33-70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions.

Titin-based stiffening of muscle fibers in Ehlers-Danlos Syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottenheijm, Coen A.C.; Voermans, Nicol C.; Hudson, Bryan D.

Tenascin-X (TNX) is an extracellular matrix glycoprotein whose absence leads to Ehlers-Danlos Syndrome (EDS). TNX-deficient EDS patients present with joint hypermobility and muscle weakness attributable to increased compliance of the extracellular matrix. We hypothesized that in response to the increased compliance of the extracellular matrix in TNX-deficient EDS patients, intracellular adaptations take place in the elastic properties of the giant muscle protein titin. We performed extensive single muscle fiber mechanical studies to determine active and passive properties in TNX-deficient EDS patients. Gel-electrophoresis, Western blotting, and microarray studies were used to evaluate titin expression and phosphorylation. X-ray diffraction was used tomore » measure myofilament lattice spacing. Passive tension of muscle fibers from TNX-deficient EDS patients was markedly increased. Myofilament extraction experiments indicated that the increased passive tension is attributable to changes in the properties of the sarcomeric protein titin. Transcript and protein data indicated no changes in titin isoform expression. Instead, differences in posttranslational modifications within titin's elastic region were found. In patients, active tension was not different at maximal activation level, but at submaximal activation level it was augmented attributable to increased calcium sensitivity. This increased calcium sensitivity might be attributable to stiffer titin molecules. In response to the increased compliance of the extracellular matrix in muscle of TNX-deficient EDS patients, a marked intracellular stiffening occurs of the giant protein titin. The stiffening of titin partly compensates for the muscle weakness in these patients by augmenting submaximal active tension generation.« less

Corrosion-induced microstructural developments in 316 stainless steel during exposure to molten Li 2BeF 4(FLiBe) salt

DOE PAGES

Zheng, Guiqiu; He, Lingfeng; Carpenter, David; ...

2016-10-12

The microstructural evaluation and characterization of 316 stainless steel samples that were tested in molten Li 2BeF 4 (FLiBe) salt were investigated in this study for evaluating its performance in high-temperature molten fluoride salts. Recently, 316 stainless steel and FLiBe salt are being actively considered as the main structural alloy and primary coolant of fluoride salt-cooled high-temperature reactor (FHR), a leading nuclear reactor concept for the next generation nuclear plants (NGNP). In support of the materials development for the FHR, high-temperature corrosion tests of 316 stainless steel in molten FLiBe salt at 700°C have been conducted in both bare graphitemore » crucibles and 316 stainless steel-lined crucibles in an inert atmosphere for up to 3000 hours. The microstructure of the tested samples was comprehensively characterized using scanning electron microscopy (SEM) in conjunction with energy dispersive x-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM) with EDS. In addition to the noticeable intergranular corrosion attack on surface, the corrosion in terms of the Cr depletion along high angle grain boundaries (15-180º) extended to 22µm in depth after 3000-hour exposure to molten FLiBe salt in graphite crucible. The coherent Σ3 grain boundary appeared high resistance to the Cr depletion. The substantial Cr depletion from the near-to-surface layer induced phase transformation from γ-martensite to α-ferrite phase (FeNi x) during corrosion at 700ºC. Furthermore, the presence of graphite in the molten salt doubled the corrosion attack depth and led to the formation of round Mo2C, hexagonal Cr 7C 3 and needle-like Al 4C 3 phase within the alloy as deep as 50 µm after 3000-hour corrosion testing. Based on the microstructural analysis, the corrosion mechanisms of 316 stainless steel in molten FLiBe salt in different corrosion crucibles were illuminated through schematic diagrams. Additionally, a thermal diffusion controlled corrosion model was developed and validated by experimental data for predicting the long-term corrosion attack depth.« less

Tribological improvements of carbon-carbon composites by infiltration of atomic layer deposited lubricious nanostructured ceramic oxides

NASA Astrophysics Data System (ADS)

Mohseni, Hamidreza

A number of investigators have reported enhancement in oxidation and wear resistant of carbon-carbon composites (CCC) in the presence of protective coating layers. However, application of a surface and subsurface coating system that can preserve its oxidation and wear resistance along with maintaining lubricity at high temperature remains unsolved. To this end, thermodynamically stable protective oxides (ZnO/Al2O3/ZrO2) have been deposited by atomic layer deposition (ALD) to infiltrate porous CCC and graphite foams in order to improve the thermal stability and wear resistance in low and high speed sliding contacts. Characterization of microstructural evolution was achieved by using energy dispersive x-ray spectroscopy (EDS) mapping in scanning electron microscope (SEM) coupled with focused ion beam (FIB), x-ray tomography, high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD). Evaluation of the tribological properties of CCC coated with abovementioned ALD thin films were performed by employing low speed pure sliding tribometer and a high speed/frequency reciprocating rig to simulate the fretting wear behavior at ambient temperature and elevated temperatures of 400°C. It was determined with x-ray tomography imaging and EDS mapping that ALD ZnO/Al2O3/ZrO2 nanolaminates and baseline ZrO2 coatings exhibited excellent conformality and pore-filling capabilities down to ˜100 microm and 1.5 mm in the porous CCC and graphite foam, respectively, which were dependent on the exposure time of the ALD precursors. XRD and HRTEM determined the crystalline phases of {0002} textured ZnO (wurtzite), amorphous Al2O3, and {101}-tetragonal ZrO2. Significant improvements up to ˜65% in the sliding and fretting wear factors were determined for the nanolaminates in comparison to the uncoated CCC. A tribochemical sliding-induced mechanically mixed layer (MML) was found to be responsible for these improvements. HRTEM confirmed the presence of a high density of ZnO shear-induced basal stacking faults inside the wear tracks responsible for intrafilm shear velocity accommodation that mitigated friction and wear.

Corrosion-induced microstructural developments in 316 stainless steel during exposure to molten Li 2BeF 4(FLiBe) salt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Guiqiu; He, Lingfeng; Carpenter, David

The microstructural evaluation and characterization of 316 stainless steel samples that were tested in molten Li 2BeF 4 (FLiBe) salt were investigated in this study for evaluating its performance in high-temperature molten fluoride salts. Recently, 316 stainless steel and FLiBe salt are being actively considered as the main structural alloy and primary coolant of fluoride salt-cooled high-temperature reactor (FHR), a leading nuclear reactor concept for the next generation nuclear plants (NGNP). In support of the materials development for the FHR, high-temperature corrosion tests of 316 stainless steel in molten FLiBe salt at 700°C have been conducted in both bare graphitemore » crucibles and 316 stainless steel-lined crucibles in an inert atmosphere for up to 3000 hours. The microstructure of the tested samples was comprehensively characterized using scanning electron microscopy (SEM) in conjunction with energy dispersive x-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM) with EDS. In addition to the noticeable intergranular corrosion attack on surface, the corrosion in terms of the Cr depletion along high angle grain boundaries (15-180º) extended to 22µm in depth after 3000-hour exposure to molten FLiBe salt in graphite crucible. The coherent Σ3 grain boundary appeared high resistance to the Cr depletion. The substantial Cr depletion from the near-to-surface layer induced phase transformation from γ-martensite to α-ferrite phase (FeNi x) during corrosion at 700ºC. Furthermore, the presence of graphite in the molten salt doubled the corrosion attack depth and led to the formation of round Mo2C, hexagonal Cr 7C 3 and needle-like Al 4C 3 phase within the alloy as deep as 50 µm after 3000-hour corrosion testing. Based on the microstructural analysis, the corrosion mechanisms of 316 stainless steel in molten FLiBe salt in different corrosion crucibles were illuminated through schematic diagrams. Additionally, a thermal diffusion controlled corrosion model was developed and validated by experimental data for predicting the long-term corrosion attack depth.« less

Effect of electronically delivered prescriptions on compliance and pharmacy wait time among emergency department patients.

PubMed

Fernando, Tasha J; Nguyen, Duy D; Baraff, Larry J

2012-01-01

The primary objectives were to assess whether electronically delivered prescriptions lead to reduced pharmacy wait time, improved patient satisfaction, and improved compliance with prescriptions. Secondary objectives included determining other reasons for noncompliance and if there was an association between prescription noncompliance and subsequent physician and emergency department (ED) visits. In this prospective study, patients discharged from the Ronald Reagan UCLA Medical Center ED with prescriptions for nonnarcotic medications were randomized to a control group who were discharged with standard written prescriptions or an intervention group who had their prescriptions electronically delivered to the pharmacy of their choice. All study participants were contacted 7 to 31 days after ED discharge for a structured telephone interview. Of the 454 patients enrolled, follow-up was successful for 224 patients (52.4%). Twenty-eight patients did not fill their prescriptions (12.5% noncompliance rate). The top three reasons patients stated for not picking up their medications were perceiving their prescription as unnecessary (n = 11), medication affordability (n = 5), and lack of time (n = 4). There was no difference in primary prescription noncompliance between the two study groups (p = 0.58). However, electronically delivered prescriptions significantly reduced the median pharmacy wait time, from 15 to 0 minutes (p = 0.001), and improved patient satisfaction at the pharmacy (p = 0.034). Neither subsequent physician nor ED visits were increased by primary prescription noncompliance. Electronically delivered prescriptions significantly minimized pharmacy wait time and improved patient satisfaction at the pharmacy, but did not improve primary compliance with prescriptions. © 2011 by the Society for Academic Emergency Medicine.

Enhancement of diffraction efficiency and storage life of poly(vinyl chloride)-based optical recording medium with incorporation of an electron donor

NASA Astrophysics Data System (ADS)

John, Beena Mary; Ushamani, M.; Sreekumar, K.; Joseph, Rani; Sudha Kartha, C.

2007-01-01

The diffraction efficiency, sensitivity, and storage life of methylene blue-sensitized poly(vinyl chloride) film was improved by the addition of an electron donor in the matrix. The addition of pyridine enhanced the diffraction efficiency by two times, and storage life of the gratings was increased to 2-3 days.

Ab initio structure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector.

PubMed

van Genderen, E; Clabbers, M T B; Das, P P; Stewart, A; Nederlof, I; Barentsen, K C; Portillo, Q; Pannu, N S; Nicolopoulos, S; Gruene, T; Abrahams, J P

2016-03-01

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enabling ab initio phasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼ 0.013 e(-) Å(-2) s(-1)) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS, SHELX) and for electron crystallography (ADT3D/PETS, SIR2014).

Single-shot coherent diffraction imaging of microbunched relativistic electron beams for free-electron laser applications.

PubMed

Marinelli, A; Dunning, M; Weathersby, S; Hemsing, E; Xiang, D; Andonian, G; O'Shea, F; Miao, Jianwei; Hast, C; Rosenzweig, J B

2013-03-01

With the advent of coherent x rays provided by the x-ray free-electron laser (FEL), strong interest has been kindled in sophisticated diffraction imaging techniques. In this Letter, we exploit such techniques for the diagnosis of the density distribution of the intense electron beams typically utilized in an x-ray FEL itself. We have implemented this method by analyzing the far-field coherent transition radiation emitted by an inverse-FEL microbunched electron beam. This analysis utilizes an oversampling phase retrieval method on the transition radiation angular spectrum to reconstruct the transverse spatial distribution of the electron beam. This application of diffraction imaging represents a significant advance in electron beam physics, having critical applications to the diagnosis of high-brightness beams, as well as the collective microbunching instabilities afflicting these systems.

Scanning Transmission Electron Microscopy | Materials Science | NREL

Science.gov Websites

mode by collecting the EDS and EELS signals point-by-point as one scans the electron probe across the . Examples of Scanning Transmission Electron Microscopy Capabilities Z-contrast image microphoto taken by

Solving the jitter problem in microwave compressed ultrafast electron diffraction instruments: Robust sub-50 fs cavity-laser phase stabilization

PubMed Central

Otto, M. R.; René de Cotret, L. P.; Stern, M. J.; Siwick, B. J.

2017-01-01

We demonstrate the compression of electron pulses in a high-brightness ultrafast electron diffraction instrument using phase-locked microwave signals directly generated from a mode-locked femtosecond oscillator. Additionally, a continuous-wave phase stabilization system that accurately corrects for phase fluctuations arising in the compression cavity from both power amplification and thermal drift induced detuning was designed and implemented. An improvement in the microwave timing stability from 100 fs to 5 fs RMS is measured electronically, and the long-term arrival time stability (>10 h) of the electron pulses improves to below our measurement resolution of 50 fs. These results demonstrate sub-relativistic ultrafast electron diffraction with compressed pulses that is no longer limited by laser-microwave synchronization. PMID:28852686

Quantum diffraction and shielding effects on the low-energy electron-ion bremsstrahlung in two-component semiclassical plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590

2015-10-15

The quantum diffraction and shielding effects on the low-energy bremsstrahlung process are investigated in two-component semiclassical plasmas. The impact-parameter analysis with the micropotential taking into account the quantum diffraction and shielding effects is employed to obtain the electron-ion bremsstrahlung radiation cross section as a function of the de Broglie wavelength, density parameter, impact parameter, photon energy, and projectile energy. The result shows that the influence of quantum diffraction and shielding strongly suppresses the bremsstrahlung radiation spectrum in semiclassical plasmas. It is found that the quantum diffraction and shielding effects have broaden the photon emission domain. It is also found thatmore » the photon emission domain is almost independent of the radiation photon energy. In addition, it is found that the influence of quantum diffraction and shielding on the bremsstrahlung spectrum decreases with an increase of the projectile energy. The density effect on the electron-ion bremsstrahlung cross section is also discussed.« less

Holographic Reconstruction of Photoelectron Diffraction and Its Circular Dichroism for Local Structure Probing

NASA Astrophysics Data System (ADS)

Matsui, Fumihiko; Matsushita, Tomohiro; Daimon, Hiroshi

2018-06-01

The local atomic structure around a specific element atom can be recorded as a photoelectron diffraction pattern. Forward focusing peaks and diffraction rings around them indicate the directions and distances from the photoelectron emitting atom to the surrounding atoms. The state-of-the-art holography reconstruction algorithm enables us to image the local atomic arrangement around the excited atom in a real space. By using circularly polarized light as an excitation source, the angular momentum transfer from the light to the photoelectron induces parallax shifts in these diffraction patterns. As a result, stereographic images of atomic arrangements are obtained. These diffraction patterns can be used as atomic-site-resolved probes for local electronic structure investigation in combination with spectroscopy techniques. Direct three-dimensional atomic structure visualization and site-specific electronic property analysis methods are reviewed. Furthermore, circular dichroism was also found in valence photoelectron and Auger electron diffraction patterns. The investigation of these new phenomena provides hints for the development of new techniques for local structure probing.

Radiation damage free ghost diffraction with atomic resolution

DOE PAGES

Li, Zheng; Medvedev, Nikita; Chapman, Henry N.; ...

2017-12-21

The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here in this paper, we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghostmore » diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several Ångstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.« less