X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

ERIC Educational Resources Information Center

Varberg, Thomas D.; Skakuj, Kacper

2015-01-01

Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

In situ study of the growth and degradation processes in tetragonal lysozyme crystals on a silicon substrate by high-resolution X-ray diffractometry

NASA Astrophysics Data System (ADS)

Kovalchuk, M. V.; Prosekov, P. A.; Marchenkova, M. A.; Blagov, A. E.; D'yakova, Yu. A.; Tereshchenko, E. Yu.; Pisarevskii, Yu. V.; Kondratev, O. A.

2014-09-01

The results of an in situ study of the growth of tetragonal lysozyme crystals by high-resolution X-ray diffractometry are considered. The crystals are grown by the sitting-drop method on crystalline silicon substrates of different types: both on smooth substrates and substrates with artificial surface-relief structures using graphoepitaxy. The crystals are grown in a special hermetically closed crystallization cell, which enables one to obtain images with an optical microscope and perform in situ X-ray diffraction studies in the course of crystal growth. Measurements for lysozyme crystals were carried out in different stages of the crystallization process, including crystal nucleation and growth, developed crystals, the degradation of the crystal structure, and complete destruction.

Enhancement of valve metal osteoconductivity by one-step hydrothermal treatment.

PubMed

Zuldesmi, Mansjur; Waki, Atsushi; Kuroda, Kensuke; Okido, Masazumi

2014-09-01

In this study, we produced super-hydrophilic surfaces of valve metals (Ti, Nb, Ta and Zr) by one-step hydrothermal treatment. Their surface characteristics and osteoconductivity using an in vivo test were then assessed. These data were compared with that of as-polished, as-anodized and both anodized+hydrothermally treated samples. Changes in surface chemistry, surface morphology and structure were investigated by X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffractometry. The results revealed that the water contact angles of valve metals were decreased by hydrothermal treatment and continued to reduce dramatically until lower than 10° after being immersed in phosphate buffered solution. By producing super-hydrophilic surfaces, the osteoconductivity of these hydrothermally treated valve metals was enhanced by up to 55%. Copyright © 2014 Elsevier B.V. All rights reserved.

Delaminating and restacking MgAl-layered double hydroxide monitored and characterized by a range of instrumental methods

NASA Astrophysics Data System (ADS)

Muráth, Szabolcs; Somosi, Zoltán; Tóth, Ildikó Y.; Tombácz, Etelka; Sipos, Pál; Pálinkó, István

2017-07-01

The delamination-restacking properties of MgAl-layered double hydroxide (MgAl-LDH) were studied in various solvents. The LDH samples were successfully delaminated in polar amides (formamide, N-methylformamide, N-methylacetamide). Usually, delamination was finalized by ultrasonic treatment. As rehydrating solutions, numerous Na-salts with single-, double- and triple-charged anions were used. Reconstruction was accomplished with anions of one or two negative charges, but triple-charged ones generally disrupted the rebuilding process, likely, because their salts with the metals of the LDH are very stable, and the thin layers can more readily transform to salts than the ordered materials. Samples and delamination-restacking processes were characterized by X-ray diffractometry (XRD), infrared spectroscopy (IR), dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX).

Synthesis and characterization of Ru-Ti[sub 4]O[sub 7] microelectrode arrays

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

He, L.; Franzen, H.F.; Vitt, J.E.

1994-04-01

A synthesis is described for Ru microelectrode arrays within a conductive Ti[sub 4]O[sub 7] ceramic matrix. Data obtained by X-ray diffractometry and scanning electron microscopy are consistent with the existence of heterogeneous mixtures of Ru particles (ca. 0.8 [mu]m diam) within the Ti[sub 4]O[sub 7] matrices. No mixed metal oxides or other new compounds are detected. Rotated disk electrodes (RDEs) constructed from the Ru-Ti[sub 4]O[sub 7] materials are compared on the basis of their voltammetric response for the oxidations of I[sup [minus

Study on different characteristics of doped tri calcium phosphate at different sintering temperatures

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

Samanta, Sujan Krishna, E-mail: itssujan@rediffmail.com; Chanda, Abhijit, E-mail: abhijitchanda.biomed@gmail.com

2016-04-13

Pure β-tricalcium phosphate (β-TCP), Zn-doped (3wt %) β-TCP and Mg- doped (3wt %) β-TCP samples were prepared by using a wet chemical precipitation synthesis technique, followed by calcination at 800 °C in air. The developed materials were subjected to sintering at different temperatures. Density and porosity were compared. The X-ray diffractometry (XRD) and Fourier-transformed infrared (FTIR) spectrometer were used to examine the changes in crystalline phases and presence of functional groups of TCP ceramics. The scanning electron microscopy (SEM) was used to study the pore formation, pore size, grain size.

Atomic force microscope studies of fullerene films - Highly stable C60 fcc (311) free surfaces

NASA Technical Reports Server (NTRS)

Snyder, Eric J.; Tong, William M.; Williams, R. S.; Anz, Samir J.; Anderson, Mark S.

1991-01-01

Atomic force microscopy and X-ray diffractometry were used to study 1500 A-thick films of pure C60 grown by sublimation in ultrahigh vacuum onto a CaF2 (111) substrte. Topographs of the films did not reveal the expected close-packed structures, but they showed instead large regions that correspond to a face-centered cubic (311) surface and distortions of this surface. The open (311) structure may have a relatively low free energy because the low packing density contributes to a high entropy of the exposed surface.

Structure of chitosan gels mineralized by sorption

NASA Astrophysics Data System (ADS)

Modrzejewska, Z.; Skwarczyńska, A.; Douglas, T. E. L.; Biniaś, D.; Maniukiewicz, W.; Sielski, J.

2015-10-01

The paper presents the structural studies of mineralized chitosan hydrogels. Hydrogels produced by using sodium beta-glycerophosphate (Na-β-GP) as a neutralizing agent. Mineralization was performed method "post loading", which consisted in sorption to the gels structure Ca ions. In order to obtain - in the structure of gels - compounds similar to the hydroxyapatites present naturally in bone tissue, gels after sorption were modified in: pH 7 buffer and sodium hydrogen phosphate. In order to determine the structural properties of the gels, the following methods were used: infrared spectroscopy with Fourier transformation, FTIR, X-ray diffractometry, XRD, scanning electron microscopy, SEM.

Effects of fines content on hydraulic conductivity and morphology of laterite soil as hydraulic barrier

NASA Astrophysics Data System (ADS)

Bello Yamusa, Yamusa; Yunus, Nor Zurairahetty Mohd; Ahmad, Kamarudin; Rahman, Norhan Abd; Sa'ari, Radzuan

2018-03-01

Laterite soil was investigated to find out the effects of fines content and to identify the micro-structural and molecular characteristics to evaluate its potentiality as a compacted soil landfill liner material. Tests were carried out on natural soil and reconstituted soil by dry weight of soil samples to determine the physical and engineering properties of the soil. All tests were carried out on the samples by adopting the British Standard 1377:1990. The possible mechanisms that contributed to the clay mineralogy were analyzed using spectroscopic and microscopic techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and X-ray diffractometry (XRD). The laterite soil was found to contain kaolinite as the major clay minerals. A minimum of 50% fines content of laterite soil met the required result for hydraulic barriers in waste containment facilities.

Observing Graphene Grow: Catalyst–Graphene Interactions during Scalable Graphene Growth on Polycrystalline Copper

PubMed Central

2013-01-01

Complementary in situ X-ray photoelectron spectroscopy (XPS), X-ray diffractometry, and environmental scanning electron microscopy are used to fingerprint the entire graphene chemical vapor deposition process on technologically important polycrystalline Cu catalysts to address the current lack of understanding of the underlying fundamental growth mechanisms and catalyst interactions. Graphene forms directly on metallic Cu during the high-temperature hydrocarbon exposure, whereby an upshift in the binding energies of the corresponding C1s XPS core level signatures is indicative of coupling between the Cu catalyst and the growing graphene. Minor carbon uptake into Cu can under certain conditions manifest itself as carbon precipitation upon cooling. Postgrowth, ambient air exposure even at room temperature decouples the graphene from Cu by (reversible) oxygen intercalation. The importance of these dynamic interactions is discussed for graphene growth, processing, and device integration. PMID:24041311

The ceramics of Malpaís of Zacapu, Michoacán, Mexico, during the Early and Middle Postclassic periods (900-1450 AD): Micro-chemical characterization of surface paintings

NASA Astrophysics Data System (ADS)

Jadot, E.; Schiavon, N.; Manso, M.

2016-05-01

Tarascan ceramic sherds from two Postclassical archaeological sites (900-1450 AD) at the Malpaís of Zacapu, Michoacán, Mexico, were investigated by combining Back-Scattered Scanning Electron Microscopy and Energy Dispersive Spectroscopy (BSEM-EDS), μ-X-Ray Diffractometry (μ-XRD), μ-X-ray Fluorescence Spectroscopy (μ-XRF) and μ-Raman Spectroscopy. These sherds are famous for their forms and decorations although the composition of its raw materials remains so far unknown and focused only on the composition of the ceramic paste. For the purpose of surface decoration characterization, the pigments used in slips and paintings were identified as hematite, magnetite, amorphous carbon, graphite and lignite. Furthermore chemical and molecular structure determination allowed the identification of technological aspects such as the firing temperatures and atmospheres used in ceramics production.

Synthesis and characterization of polyethylenimine-based iron oxide composites as novel contrast agents for MRI.

PubMed

Masotti, A; Pitta, A; Ortaggi, G; Corti, M; Innocenti, C; Lascialfari, A; Marinone, M; Marzola, P; Daducci, A; Sbarbati, A; Micotti, E; Orsini, F; Poletti, G; Sangregorio, C

2009-04-01

Use of polyethylenimines (PEIs) of different molecular weight and selected carboxylated-PEI derivatives (PEI-COOH) in the synthesis and stabilization of iron oxide nanoparticles, to obtain possible multifunctional contrast agents. Oxidation of Fe(II) at slightly elevated pH and temperature resulted in the formation of highly soluble and stable nanocomposites of iron oxides and polymer. Composites were characterized and studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffractometry, AC and DC magnetometry, NMR relaxometry and magnetic resonance imaging (MRI). From AFM the dimensions of the aggregates were found to be in the ~150-250 nm size region; the mean diameter of the magnetic core of the compounds named PEI-25, PEI-500 and PEI-COOH60 resulted d approximately 20 +/- 5 nm for PEI-25, d approximately 9.5 +/- 1.0 nm for PEI-500 and d approximately 6.8 +/- 1.0 nm for PEI-COOH60. In PEI-COOH60 TEM and X-ray diffractometry revealed small assemblies of mineral magnetic cores with clear indications that the main constituents are maghemite and/or magnetite as confirmed by AC and DC SQUID magnetometry. For PEI-COOH60, the study of NMR-dispersion profiles revealed r (1) and r (2) relaxivities comparable to superparamagnetic iron-oxide commercial compounds in the whole investigated frequency range 7 < or = nu < or = 212 MHz. PEI-25 was studied as possible MRI contrast agent (CA) to map the cerebral blood volume (CBV) and cerebral blood flow (CBF) in an animal model obtaining promising results. The reported compounds may be further functionalized to afford novel multifunctional systems for biomedical applications.

Synthesis and Characterization of Cobalt Substituted Zinc Ferrite Nanoparticles by Microwave Combustion Method.

PubMed

Sundararajan, M; Kennedy, L John; Vijaya, J Judith

2015-09-01

Pure and cobalt doped zinc ferrites were prepared by microwave combustion method using L-arginine as a fuel. The prepared samples were characterized by various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, Fourier transformed infrared (FT-IR) spectroscopy, photoluminescence spectroscopy and UV-Visible diffuse reflectance spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis confirmed the formation of zinc ferrites normal spinel-type structure with an average crystallite sizes in the range, 25.69 nm to 35.68 nm. The lattice parameters decreased as cobalt fraction was increased. The HR-SEM images showed nanoparticles are agglomerated. The estimated band gap energy value was found to decrease with an increase in cobalt content (1.87 to 1.62 eV). Broad visible emissions are observed in the photoluminescence spectra. A gradual increase in the coercivity and saturation magnetization (M(s)) were noted at relatively higher cobalt doping fractions.

From nicotinate-containing layered double hydroxides (LDHs) to NAD coenzyme-LDH nanocomposites - Syntheses and structural characterization by various spectroscopic methods

NASA Astrophysics Data System (ADS)

Muráth, Szabolcs; Dudás, Csilla; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

2017-07-01

The syntheses of nicotinate anion- and NAD coenzyme-layered double hydroxide (LDH) composites were performed with the aim of having the organic component among the layers. In-house prepared CaAl-LDHs were the host materials. Intercalation was attempted by direct ion exchange or by the dehydration-rehydration method applying aqueous solvent mixtures (containing ethanol, propanol, acetone, N,N-dimethylformamide). For structural characterization, beside X-ray diffractometry, X-ray photoelectron and IR spectroscopies, transmission and scanning electron microscopies as well as energy-dispersive X-ray analysis were used. Molecular modelling served for the visualization of the arrangements of the intercalated ions among the layers of the LDH samples. Although not all the intercalation methods and solvent mixtures led to intercalated composite materials, successful ones could be identified. The combination of spectroscopic methods helped in proposing sensible spatial arrangements for the intercalated anions. The NAD-CaAl-LDH composite proved to be an active catalyst in the oxidation of hydroquinone to 1,4-bezoquinoe in the presence of H2O2.

Preparation and analysis of multilayer composites based on polyelectrolyte complexes

NASA Astrophysics Data System (ADS)

Petrova, V. A.; Orekhov, A. S.; Chernyakov, D. D.; Baklagina, Yu. G.; Romanov, D. P.; Kononova, S. V.; Volod'ko, A. V.; Ermak, I. M.; Klechkovskaya, V. V.; Skorik, Yu. A.

2016-11-01

A method for preparing multilayer film composites based on chitosan has been developed by the example of polymer pairs: chitosan-hyaluronic acid, chitosan-alginic acid, and chitosan-carrageenan. The structure of the composite films is characterized by X-ray diffractometry and scanning electron microscopy. It is shown that the deposition of a solution of hyaluronic acid, alginic acid, or carrageenan on a chitosan gel film leads to the formation of a polyelectrolyte complex layer at the interface, which is accompanied by the ordering of chitosan chains in the surface region; the microstructure of this layer depends on the nature of contacting polymer pairs.

Solid-state characterization of nevirapine.

PubMed

Sarkar, Mahua; Perumal, O P; Panchagnula, R

2008-09-01

The purpose of this investigation is to characterize nevirapine from commercial samples and samples crystallized from different solvents under various conditions. The solid-state behavior of nevirapine samples was investigated using a variety of complementary techniques such as microscopy (optical, polarized, hot stage microscopy), differential scanning calorimeter, thermogravimetric analysis, Fourier transform infrared spectroscopy and powder X-ray diffractometry. The commercial samples of nevirapine had the same polymorphic crystalline form with an anhedral crystal habit. Intrinsic dissolution of nevirapine was similar for both the commercial batches. Powder dissolution showed pH dependency, with maximum dissolution in acidic pH and there was no significant effect of particle size. The samples recrystallized from different solvent systems with varying polarity yielded different crystal habits. Stirring and degrees of supersaturation influenced the size and shape of the crystals. The recrystallized samples did not produce any new polymorphic form, but weak solvates with varying crystal habit were produced. Recrystallized samples showed differences in the x-ray diffractograms. However, all the samples had the same internal crystal lattice as revealed from their similar melting points and heat of fusion. The intrinsic dissolution rate of recrystallized samples was lower than the commercial sample. It was found that the compression pressure resulted in desolvation and partial conversion of the crystal form. After compression, the recrystallized samples showed similar x-ray diffractograms to the commercial sample. Amorphous form showed slightly higher aqueous solubility than the commercial crystalline form.

Energy dispersive X-ray fluorescence spectroscopy/Monte Carlo simulation approach for the non-destructive analysis of corrosion patina-bearing alloys in archaeological bronzes: The case of the bowl from the Fareleira 3 site (Vidigueira, South Portugal)

NASA Astrophysics Data System (ADS)

Bottaini, C.; Mirão, J.; Figuereido, M.; Candeias, A.; Brunetti, A.; Schiavon, N.

2015-01-01

Energy dispersive X-ray fluorescence (EDXRF) is a well-known technique for non-destructive and in situ analysis of archaeological artifacts both in terms of the qualitative and quantitative elemental composition because of its rapidity and non-destructiveness. In this study EDXRF and realistic Monte Carlo simulation using the X-ray Monte Carlo (XRMC) code package have been combined to characterize a Cu-based bowl from the Iron Age burial from Fareleira 3 (Southern Portugal). The artifact displays a multilayered structure made up of three distinct layers: a) alloy substrate; b) green oxidized corrosion patina; and c) brownish carbonate soil-derived crust. To assess the reliability of Monte Carlo simulation in reproducing the composition of the bulk metal of the objects without recurring to potentially damaging patina's and crust's removal, portable EDXRF analysis was performed on cleaned and patina/crust coated areas of the artifact. Patina has been characterized by micro X-ray Diffractometry (μXRD) and Back-Scattered Scanning Electron Microscopy + Energy Dispersive Spectroscopy (BSEM + EDS). Results indicate that the EDXRF/Monte Carlo protocol is well suited when a two-layered model is considered, whereas in areas where the patina + crust surface coating is too thick, X-rays from the alloy substrate are not able to exit the sample.

Capacity fading of LiAlyNi1-x-yCoxO2 cathode for lithium-ion batteries during accelerated calendar and cycle life tests (effect of depth of discharge in charge-discharge cycling on the suppression of the micro-crack generation of LiAlyNi1-x-yCoxO2 particle)

NASA Astrophysics Data System (ADS)

Watanabe, Shoichiro; Kinoshita, Masahiro; Hosokawa, Takashi; Morigaki, Kenichi; Nakura, Kensuke

2014-08-01

Cycle performance of a LiAl0.10Ni0.76Co0.14O2 (NCA) cathode/graphite cell closely depended on the range of depth of discharge in charge-discharge processes (ΔDOD). When ΔDOD was 10-70%, cycle performance at 25 °C was maintained even at 60 °C. Deterioration phenomena were analyzed by electrochemical method, X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), and micro-cracks in NCA particles were analyzed with cross-sectional views by scanning electron microscopy (SEM). Many micro-cracks were observed only after a 0-100% DOD region cycle test. Cycle tests in several restricted ΔDOD conditions showed that the deterioration was closely related to not the upper and lower limits of DOD or operation voltage but the width of ΔDOD.

Quantitative measurement of indomethacin crystallinity in indomethacin-silica gel binary system using differential scanning calorimetry and X-ray powder diffractometry.

PubMed

Pan, Xiaohong; Julian, Thomas; Augsburger, Larry

2006-02-10

Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) methods were developed for the quantitative analysis of the crystallinity of indomethacin (IMC) in IMC and silica gel (SG) binary system. The DSC calibration curve exhibited better linearity than that of XRPD. No phase transformation occurred in the IMC-SG mixtures during DSC measurement. The major sources of error in DSC measurements were inhomogeneous mixing and sampling. Analyzing the amount of IMC in the mixtures using high-performance liquid chromatography (HPLC) could reduce the sampling error. DSC demonstrated greater sensitivity and had less variation in measurement than XRPD in quantifying crystalline IMC in the IMC-SG binary system.

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser

NASA Astrophysics Data System (ADS)

Liang, Chunyong; Wang, Hongshui; Yang, Jianjun; Li, Baoe; Yang, Yang; Li, Haipeng

2012-11-01

Biocompatibility of the micro-patterned NiTi surface produced by femtosecond laser (FSL) was studied in this work. The surface characteristics of the laser treated NiTi alloys were investigated by scanning electron microscopy (SEM), atom force microscopy (AFM), X-ray diffractometry (XRD) and X-ray photoelectron spectrum (XPS). The biocompatibility was evaluated by in vitro cell culture test. The results showed that, grooves, ripples, which covered by nanoparticles were formed on the sample surfaces, and the Ni/Ti ratio on the alloy surface increased with increasing laser energy. The crystal structure was not changed by laser treatment. However, the cell culture test proved that the micro-patterns induced by FSL were beneficial to improve the biocompatibility of NiTi alloys: the growth of osteoblasts oriented along the grooves, a large amount of synapses and filopodias were formed due to the ripples, holes and nanoparticles on the alloy surface, and the proliferation rate and alkaline phosphatase (ALP) content of cells were increased after FSL treatment. However, due to the toxicity of Ni ions on cell growth, the NiTi alloy surface should not be treated by laser fluence of more than 3.82 J/cm2 to obtain the ideal biocompatibility.

Ultrastructure of selected struvite-containing urinary calculi from cats.

PubMed

Neumann, R D; Ruby, A L; Ling, G V; Schiffman, P S; Johnson, D L

1996-01-01

To elucidate the ultrastructural details of struvite-containing urinary calculi from cats. Specimens studied were inclusive of the range of textures visible during preliminary analysis by use of a stereoscopic dissecting microscope. Textural types, which were used to infer crystal growth conditions, were differentiated with regard to crystal habit, crystal size, growth orientation, and primary porosity. Thirty specimens were selected from a collection of approximately 1,600 feline urinary calculi: 20 of these were composed entirely of struvite, and 10 consisted of struvite and calcium phosphate (apatite). Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron probe microanalysis. Four textural types were recognized among struvite calculi, whereas 2 textural types of struvite-apatite calculi were described. The presence of minute, well interconnected primary pores in struvite-containing urinary calculi from cats is an important feature, which may promote possible interaction of calculi with changes in urine composition. Primary porosity, which can facilitate interaction between the calculus and changing urine composition, may explain the efficacy of dietary or medicinal manipulations to promote the dissolution of struvite-containing uroliths from this species.

The relationship between crystal structure and methyl and t-butyl group dynamics in van der Waals organic solids

NASA Astrophysics Data System (ADS)

Beckmann, Peter A.; Paty, Carol; Allocco, Elizabeth; Herd, Maria; Kuranz, Carolyn; Rheingold, Arnold L.

2004-03-01

We report x-ray diffractometry in a single crystal of 2-t-butyl-4-methylphenol (TMP) and low-frequency solid state nuclear magnetic resonance (NMR) proton relaxometry in a polycrystalline sample of TMP. The x-ray data show TMP to have a monoclinic, P21/c, structure with eight molecules per unit cell and two crystallographically inequivalent t-butyl group (C(CH3)3) sites. The proton spin-lattice relaxation rates were measured between 90 and 310 K at NMR frequencies of 8.50, 22.5, and 53.0 MHz. The relaxometry data is fitted with two models characterizing the dynamics of the t-butyl groups and their constituent methyl groups, both of which are consistent with the determined x-ray structure. In addition to presenting results for TMP, we review previously reported x-ray diffractometry and low-frequency NMR relaxometry in two other van der Waals solids which have a simpler structure. In both cases, a unique model for the reorientational dynamics was found. Finally, we review a similar previously reported analysis in a van der Waals solid with a very complex structure in which case fitting the NMR relaxometry requires very many parameters and serves mainly as a flag for a careful x-ray diffraction study.

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

Pratapa, S.; Susanti, L.; Insany, Y. A. S.

Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgO{center_dot}Al{sub 2}O{sub 3}(spinel), Y{sub 2}O{sub 3}(yttria) and Fe{sub 3}O{sub 4}(ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100 deg. C, followed by heating at 450 deg. C, 750 deg. C, 600 deg. C and 200 deg.more » C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X-ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line-broadening analysis using single-line and Rietveld-based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders, indicating different crystallite sizes. It was also found that, particularly for spinel and yttria, the diffraction peaks exhibited 'longer' tails, indicating broader crystallite size distribution. The average crystallite size for the powders ranged from 3 to 70 nm. The results could then be used as 'fingerprints' for nanocrystallinity using x-ray diffractometry. The XRD crystallite sizes for yttria and ferrite nanocrystals are in fair agreement with their counterparts from electron microscopy observation.« less

Application of film-casting technique to investigate drug-polymer miscibility in solid dispersion and hot-melt extrudate.

PubMed

Parikh, Tapan; Gupta, Simerdeep Singh; Meena, Anuprabha K; Vitez, Imre; Mahajan, Nidhi; Serajuddin, Abu T M

2015-07-01

Determination of drug-polymer miscibility is critical for successful development of solid dispersions. This report details a practical method to predict miscibility and physical stability of drug with various polymers in solid dispersion and, especially, in melt extrudates by applying a film-casting technique. Mixtures of itraconazole (ITZ) with hydroxypropylmethylcellulose phthalate (HPMCP), Kollidon(®) VA 64, Eudragit(®) E PO, and Soluplus(®) were film-casted, exposed to 40°C/75% RH for 1 month and then analyzed using differential scanning calorimetry (DSC), powder X-ray diffractometry, and polarized light microscopy (PLM). ITZ had the highest miscibility with HPMCP, being miscible at drug to polymer ratio of 6:4 (w/w). There was a downward trend of lower miscibility with Soluplus(®) (miscible at 3:7, w/w, and a few microcrystals present at 4:6, w/w), Kollidon(®) VA 64 (2:8, w/w) and Eudragit(®) E PO (<1:9, w/w). PLM was found more sensitive to detect drug crystallization than DSC and powder X-ray diffractometry. There was general correlation between results of film casting and hot-melt extrusion (HME) using a twin screw extruder. For ITZ-Soluplus(®) mixtures, HME at 4:6 (w/w) resulted in a single phase, whereas drug crystallization was observed at higher drug load. HME of ITZ-Kollidon(®) VA 64 mixtures also correlated well with the miscibility predicted by film casting. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Sample holder for X-ray diffractometry

DOEpatents

Hesch, Victor L.

1992-01-01

A sample holder for use with X-ray diffractometers with the capability to rotate the sample, as well as to adjust the position of the sample in the x, y, and z directions. Adjustment in the x direction is accomplished through loosening set screws, moving a platform, and retightening the set screws. Motion translators are used for adjustment in the y and z directions. An electric motor rotates the sample, and receives power from the diffractometer.

Analysis of synthetic diamond single crystals by X-ray topography and double-crystal diffractometry

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

Prokhorov, I. A., E-mail: igor.prokhorov@mail.ru; Ralchenko, V. G.; Bolshakov, A. P.

2013-12-15

Structural features of diamond single crystals synthesized under high pressure and homoepitaxial films grown by chemical vapor deposition (CVD) have been analyzed by double-crystal X-ray diffractometry and topography. The conditions of a diffraction analysis of diamond crystals using Ge monochromators have been optimized. The main structural defects (dislocations, stacking faults, growth striations, second-phase inclusions, etc.) formed during crystal growth have been revealed. The nitrogen concentration in high-pressure/high-temperature (HPHT) diamond substrates is estimated based on X-ray diffraction data. The formation of dislocation bundles at the film-substrate interface in the epitaxial structures has been revealed by plane-wave topography; these dislocations are likelymore » due to the relaxation of elastic macroscopic stresses caused by the lattice mismatch between the substrate and film. The critical thicknesses of plastic relaxation onset in CVD diamond films are calculated. The experimental techniques for studying the real diamond structure in optimizing crystal-growth technology are proven to be highly efficient.« less

Photoluminescent properties of complex metal oxide nanopowders for gas sensing

NASA Astrophysics Data System (ADS)

Bovhyra, R. V.; Mudry, S. I.; Popovych, D. I.; Savka, S. S.; Serednytski, A. S.; Venhryn, Yu. I.

2018-03-01

This work carried out research on the features of photoluminescence of the mixed and complex metal oxide nanopowders (ZnO/TiO2, ZnO/SnO2, Zn2SiO4) in vacuum and gaseous ambient. The nanopowders were obtained using pulsed laser reactive technology. The synthesized nanoparticles were characterized by X-ray diffractometry, energy-dispersive X-ray analysis, and scanning and transmission electron microscopy analysis for their sizes, shapes and collocation. The influence of gas environment on the photoluminescence intensity was investigated. A change of ambient gas composition leads to a rather significant change in the intensity of the photoluminescence spectrum and its deformation. The most significant changes in the photoluminescent spectrum were observed for mixed ZnO/TiO2 nanopowders. This obviously is the result of a redistribution of existing centers of luminescence and the appearance of new adsorption centers of luminescence on the surface of nanopowders. The investigated nanopowders can be effectively used as sensing materials for the construction of the multi-component photoluminescent sensing matrix.

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

NASA Astrophysics Data System (ADS)

Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

2016-01-01

A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

Enhanced photocatalytic activity of Fe-doped TiO2 coated on N-doped activated carbon composites for photocatalytic degradation of dyeing wastewater

NASA Astrophysics Data System (ADS)

Zhou, Jie; Zhu, Beibei; Wang, Lu; Li, Ya; Qiao, Qichen

2017-10-01

Fe-doped TiO2 coated on N-doped activated carbon (Fe-TiO2/N-AC, FTNA) composites were synthesized simply by a straightforward two-step procedure. The obtained materials were characterized by X-ray diffractometry (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopies. Through the degradation of dyeing wastewater, the photocatalytic activity of FTNA was investigated under ultraviolet light irradiation. The results showed that containing N functional groups were successfully introduced onto the surface of the activated carbon. Compared with Fe-TiO2/AC (FTA), FTNA with average particle size of TiO2 13.6 nm and surface area 1007.89 m2/g showed a higher photoactivity. Additionally, for the photocatalytic degradation of dyeing wastewater, the optimum N content and catalyst content were 0.8% and 5g/L, respectively. Moreover, the photoactivity and photo stability of the catalyst after many runs was also evaluated.

In situ removal of arsenic from groundwater by using permeable reactive barriers of organic matter/limestone/zero-valent iron mixtures.

PubMed

Gibert, O; de Pablo, J; Cortina, J-L; Ayora, C

2010-08-01

In this study, two mixtures of municipal compost, limestone and, optionally, zero-valent iron were assessed in two column experiments on acid mine treatment. The effluent solution was systematically analysed throughout the experiment and precipitates from both columns were withdrawn for scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry analysis and, from the column containing zero-valent iron, solid digestion and sequential extraction analysis. The results showed that waters were cleaned of arsenic, metals and acidity, but chemical and morphological analysis suggested that metal removal was not due predominantly to biogenic sulphide generation but to pH increase, i.e. metal (oxy)hydroxide and carbonate precipitation. Retained arsenic and metal removal were clearly associated to co-precipitation with and/or sorption on iron and aluminum (oxy)hydroxides. An improvement on the arsenic removal efficiency was achieved when the filling mixture contained zero-valent iron. Values of arsenic concentrations were then always below 10 microg/L.

RF sputtered silicon and hafnium nitrides as applied to 440C steel

NASA Technical Reports Server (NTRS)

Grill, A.; Aron, P. R.

1984-01-01

Silicon nitride and hafnium nitride coatings were deposited on oxidized and unoxidized 440C stainless steel substrates. Sputtering was done in mixtures of argon and nitrogen gases from pressed powder silicon nitride and from hafnium metal targets. The coatings and the interface between the coating and substrate were investigated by X-ray diffractometry, scanning electron microscopy, energy dispersive X-ray analysis and Auger electron spectroscopy. Oxide was found at all interfaces with an interface width of at least 600 A for the oxidized substrates and at least 300 A for the unoxidized substrates. Scratch test results demonstrate that the adhesion of hafnium nitride to both oxidized and unoxidized 440C is superior to that of silicon nitride. Oxidized 440C is found to have increased adhesion, to both nitrides, over that of unoxidized 440C. Coatings of both nitrides deposited at 8 mtorr were found to have increased adhesion to both oxidized and unoxidized 440C over those deposited at 20 mtorr.

Mesoporous silica templated zirconia nanoparticles

NASA Astrophysics Data System (ADS)

Ballem, Mohamed A.; Córdoba, José M.; Odén, Magnus

2011-07-01

Nanoparticles of zirconium oxide (ZrO2) were synthesized by infiltration of a zirconia precursor (ZrOCl2·8H2O) into a SBA-15 mesoporous silica mold using a wet-impregnation technique. X-ray diffractometry and high-resolution transmission electron microscopy show formation of stable ZrO2 nanoparticles inside the silica pores after a thermal treatment at 550 °C. Subsequent leaching out of the silica template by NaOH resulted in well-dispersed ZrO2 nanoparticles with an average diameter of 4 nm. The formed single crystal nanoparticles are faceted with 110 surfaces termination suggesting it to be the preferred growth orientation. A growth model of these nanoparticles is also suggested.

Corrosion products of carbonation induced corrosion in existing reinforced concrete facades

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

Köliö, Arto; Honkanen, Mari; Lahdensivu, Jukka

Active corrosion in reinforced concrete structures is controlled by environmental conditions and material properties. These factors determine the corrosion rate and type of corrosion products which govern the total achieved service life. The type and critical amount of corrosion products were studied by electron microscopy and X-ray diffractometry on concrete and reinforcement samples from existing concrete facades on visually damaged locations. The corrosion products in outdoor environment exposed concrete facades are mostly hydroxides (Feroxyhite, Goethite and Lepidocrocite) with a volume ratio to Fe of approximately 3. The results can be used to calibrate calculation of the critical corrosion penetration ofmore » concrete facade panels.« less

Various types of semiconductor photocatalysts modified by CdTe QDs and Pt NPs for toluene photooxidation in the gas phase under visible light

NASA Astrophysics Data System (ADS)

Marchelek, M.; Grabowska, E.; Klimczuk, T.; Lisowski, W.; Zaleska-Medynska, A.

2017-01-01

A novel synthesis process was used to prepare TiO2 microspheres, TiO2 P-25, SrTiO3 and KTaO3 decorated by CdTe QDs and/or Pt NPs. The effect of semiconductor matrix, presence of CdTe QDs and/or Pt NPs on the semiconductor surface as well as deposition technique of Pt NPs (photodeposition or radiolysis) on the photocatalytic activity were investigated. The as-prepared samples were characterized by X-ray powder diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) with energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), photoluminescence spectrometry (PL), Fourier transform infrared (FT-IR) and Raman spectra, diffuse reflectance spectroscopy (DRS) and BET surface area analysis. The photocatalytic decomposition of toluene in gas phase, activated by light-emitting diodes (LEDs), with the CdTe/Pt nanoparticles-modified TiO2 microspheres, P25, SrTiO3 and KTaO3 semiconductors was investigated under UV-vis and visible irradiation.The results showed that the photoactivity depends on semiconductor matrix. The highest photoactivity under Vis light was observed for KTaO3/CdTe-Pt(R) sample (56% of toluene was decompose after 30 min of irradiation). The efficiency of the most active sample was 3 times higher than result for P25 and two times higher than for unmodified KTaO3.

Synthesis and characterization of zeolites prepared from industrial fly ash.

PubMed

Franus, Wojciech; Wdowin, Magdalena; Franus, Małgorzata

2014-09-01

In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 75 °C), Na-P1 (20 g fly ash, 0.5 dm(3) of 3 mol · dm(-3) NaOH, 95 °C), and sodalite (20 g fly ash, 0.8 dm(3) of 5 mol · dm(-3) NaOH + 0.4 dm(3) of 3 mol · dm(-3) NaCl, 95 °C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N2 isotherm adsorption/desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m(2) · g(-1), while for the Na-P1 and sodalite it was 71 and 33 m(2) · g(-1), respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq · g(-1), Na-P1 at 0.72 meq · g(-1), and sodalite at 0.56 meq · g(-1). The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination.

Structural properties of H-implanted InP crystals

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

Bocchi, C.; Franzosi, P.; Lazzarini, L.

1993-07-01

H has been implanted in InP crystals at the energy E [equals] 100 keV and at different doses ranging from [sigma] [equals] 1 x 10[sup 13] to [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2]. The depth dependence of the elastic lattice strain has been investigated by high resolution X-ray diffractometry. The implantation produces a lattice dilation. The strain increases with increasing depth, reaches the maximum at about 0.75 [mu]m, and then decreases rapidly; moreover the maximum strain is proportional to the dose. No extended crystal defects have been detected by transmission electron microscopy up to [sigma] <1 x 10[supmore » 16] cm[sup [minus]2] a buried amorphous layer 28 nm in thickness has been observed at the same depth where the strain is maximum. The thickness of the amorphous layer increases by further increasing the dose and reaches a value of about 0.18 [mu]m for [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2].« less

Fine Structure Study of the Plasma Coatings B4C-Ni-P

NASA Astrophysics Data System (ADS)

Kornienko, E. E.; Bezrukova, V. A.; Kuz'min, V. I.; Lozhkin, V. S.; Tutunkova, M. K.

2017-12-01

The article considers structure of coatings formed of the B4C-Ni-P powder. The coatings were deposited using air-plasma spraying with the unit for annular injection of powder. The pipes from steel 20 (0.2 % C) were used as a substrate. The structure and phase composition of the coatings were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. It is shown that high-density composite coatings consisting of boron carbide particles distributed in the nickel boride metal matrix are formed using air-plasma spraying. The areas with round inclusions characterized by the increased amount of nickel, phosphorus and boron are located around the boron carbide particles. Boron oxides and nickel oxides are also present in the coatings. Thin interlayers with amorphous-crystalline structure are formed around the boron carbide particles. The thickness of these interlayers does not exceed 1 μm. The metal matrix material represents areas with nanocrystalline structure and columnar crystals.

Self-assembled biomimetic superhydrophobic CaCO3 coating inspired from fouling mineralization in geothermal water.

PubMed

Wang, Gong G; Zhu, Li Q; Liu, Hui C; Li, Wei P

2011-10-18

Inspired from fouling self-mineralization in geothermal water, a novel biomimetic cactuslike CaCO(3) coating with superhydrophobic features is reported in this letter. The structure, morphologies, and phases of the CaCO(3) coating were characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, and infrared spectrophotometry. After prenucleation treatment, a continuous cactuslike CaCO(3) coating with hierarchical nano- and microstructures was self-assembled on stainless steel surfaces after immersion in simulated geothermal water at 50 °C for 48 h. After being modified with a low-surface-energy monolayer of sodium stearate, the as-prepared coating exhibited superhydrophobic properties with a water contact angle of 158.9° and a sliding angle of 2°. Therefore, this work might open up a new application field of geothermal resources and provide insight into designing multidimensional structures with functional applications, including superhydrophobic surfaces. © 2011 American Chemical Society

Fabrication of Ti-0.48Al Alloy by Centrifugal Casting.

PubMed

Park, Jong Bum; Lee, Jung-Il; Ryu, Jeong Ho

2018-09-01

Many of the unique properties of TiAl alloys that make are attractive for use in high-temperature structural applications also make it challenging to process them into useful products. Cast TiAl is rapidly nearing commercialization, particularly in the vehicle industry, owing to its low production cost. In this study, the centrifugal casting of a TiAl (Ti-48%Al, mole fraction) turbocharger was simulated and an experimental casting was created in vacuum using an induction melting furnace coupled to a ceramic composite mold. Numerical simulation results agreed with the experiment. The crystal structure, microstructure, and chemical composition of the TiAl prepared by centrifugal casting were studied by X-ray diffractometry, optical microscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). FE-SEM and EDS examinations of the TiAl casting revealed that the thickness of the oxide layer (α-case) was typically less than 35 μm.

Manganese porphyrin immobilized on magnetic MCM-41 nanoparticles as an efficient and reusable catalyst for alkene oxidations with sodium periodate

NASA Astrophysics Data System (ADS)

Hajian, Robabeh; Ehsanikhah, Amin

2018-01-01

This study describes the immobilization of tetraphenylporphyrinatomanganese(III) chloride, (MnPor), onto imidazole functionalized MCM-41 with magnetite nanoparticle core (Fe3O4@MCM-41-Im). The resultant material (Fe3O4@MCM-41-Im@MnPor) was characterized by X-ray diffractometry (XRD), Fourier transform infra-red (FT-IR), diffuse reflectance UV-Vis spectrophotometry (DR UV-Vis), field emission scanning electron microscopy (FESEM), Inductively coupled plasma (ICP), analyzer transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area. This new heterogenized catalyst was applied as an efficient catalyst for the epoxidation of a variety of cyclic and linear olefins with NaIO4 under mild conditions. The prepared catalyst can be easily recovered through the application of an external magnet, and reused several times without any significant decrease in activity and magnetic properties.

High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

2000-01-01

We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

Enhanced UV-visible response of bismuth subcarbonate nanowires for degradation of xanthate and photocatalytic reaction mechanism.

PubMed

Cui, Kuixin; He, Yuehui; Jin, Shengming

2016-04-01

(BiO)2CO3 nanowires were prepared by simple hydrothermal treatment of commercial Bi2O3 powders and characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of (BiO)2CO3 nanowires was studied through degradation of sodium isopropyl xanthate. Photocatalytic experimental results indicated that the as-prepared (BiO)2CO3 nanowires show high photocatalytic efficiency. Photocatalytic activity increased after two cycles. Time-dependent UV-vis spectra demonstrated that the final degradation products included isopropyl alcohol and carbon disulfide. UV-vis diffuse reflection spectra showed that the band gap of the as-prepared (BiO)2CO3 nanowires and recycled (BiO)2CO3 nanowires were 2.75 eV and 1.15 eV, respectively. XPS results indicated that formation of Bi2S3@(BiO)2CO3 core-shell nanowires occurred after recycled photodegradation of isopropyl xanthate owing to existence of two types of Bi configurations in the recycled (BiO)2CO3 nanowires. A probable degradation mechanism of isopropyl xanthate was also proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of intrinsic electronic defect states on the morphology and optoelectronic properties of Sn-rich SnS particles

NASA Astrophysics Data System (ADS)

Singh, Chetan C.; Panda, Emila

2018-05-01

A small variation in the elemental composition of a chemical compound can cause the formation of additional electronic defect states in the material, thereby altering the overall microstructure and thus induced properties. In this work, we observed chemical constitution-induced modification in the morphology and optoelectronic properties of SnS. To this end, SnS particles were prepared using the solution chemical route and were characterized using a wide range of experimental techniques, such as x-ray diffractometry, field emission scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometry, and scanning tunneling spectroscopy (STS). All these SnS particles are found to be Sn-rich and p-type. However, distinctly different morphologies (i.e., flower-like and aggregated ones) are observed. These are then correlated with the electronic defect states, which are induced because of the presence of Sn vacancies, Sn antisites, and/or Sn interstitials. A combination of EDS, XPS, and STS data confirmed the presence of a higher concentration of Sn vacancies along with lower quantities of Sn interstitials and/or antisites in the SnS particles with flower-like morphologies giving rise to higher hole concentration, which subsequently leads to reduced transport, optical band gaps, and barrier heights.

Passivation of hematite nanorod photoanodes with a phosphorus overlayer for enhanced photoelectrochemical water oxidation

NASA Astrophysics Data System (ADS)

Xiong, Dehua; Li, Wei; Wang, Xiaoguang; Liu, Lifeng

2016-09-01

Hematite (i.e., α-Fe2O3) nanorod photoanodes passivated with a phosphorus overlayer have been fabricated by decomposing sodium hypophosphite (NaH2PO2) at a low temperature over the hematite nanorod surface. Extensive scanning electron microscopy, transmission electron microscopy, x-ray diffractometry and UV-vis spectroscopy characterizations confirm that conformal deposition of an amorphous phosphorus overlayer does not change the crystal structure, morphology, and optical absorption properties of hematite photoanodes. X-ray photoelectron spectroscopy reveals that phosphorus in the deposited overlayer exists in an oxidized state. Comprehensive steady-state polarization, transient photocurrent response, and impedance spectroscopy measurements as well as Mott-Schottky analysis manifest that the phosphorus overlayer is able to effectively passivate surface states and suppress electron-hole recombination, substantially enhancing the photocurrent for water oxidation. Combining the phosphorization treatment with two-step thermal activation, a photocurrent density of 1.1 mA cm-2 is achieved at 1.23 V versus reversible hydrogen electrode under illumination of 100 mW cm-2, ca 55 times higher than that of the non-activated pristine hematite photoanode measured under the same conditions. The simple and fast phosphorization strategy we present here can be readily applied to passivate surfaces of other semiconductor photoelectrodes to improve their photoelectrochemical performance.

Self-propagating high-temperature synthesis and luminescent properties of ytterbium doped rare earth (Y, Sc, Lu) oxides nanopowders

NASA Astrophysics Data System (ADS)

Permin, D. A.; Novikova, A. V.; Balabanov, S. S.; Gavrishchuk, E. M.; Kurashkin, S. V.; Savikin, A. P.

2018-04-01

This paper describes a comparative study of structural and luminescent properties of 5%Yb-doped yttrium, scandium, and lutetium oxides (Yb:RE2O3) powders and ceramics fabricated by self-propagating high-temperature synthesis. According to X-ray diffractometry and electron microscopy the chosen method ensures preparation of low-agglomerated cubic Ctype crystal structured powders at one step. No crucial differences in luminescence spectra were found the Yb:RE2O3 powders and ceramics. It was shown that the emission lifetimes of the Yb:RE2O3 powders are lowered by crystal structure defects, while its values for ceramics samples are compared to that of monocrystals and more influenced by rare earth impurities.

Thickness dependence of the exchange bias in epitaxial manganite bilayers

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

Kobrinskii, A. L.; Goldman, A. M.; Varela del Arco, Maria

Exchange bias has been studied in a series of La{sub 2/3}Ca{sub 1/3}MnO{sub 3}/La{sub 1/3}Ca{sub 2/3}MnO{sub 3} bilayers grown on (001) SrTiO{sub 3} substrates by ozone-assisted molecular-beam epitaxy. The high crystalline quality of the samples and interfaces has been verified using high-resolution x-ray diffractometry and Z-contrast scanning transmission electron microscopy with electron-energy-loss spectroscopy. The dependence of exchange bias on the thickness of the antiferromagnetic layer has been investigated. A critical value for the onset of the hysteresis loop shift has been determined. An antiferromagnetic anisotropy constant has been obtained by fitting the results to the generalized Meiklejohn-Bean model.

Selective laser sintering of single-phase powder Cr-V tool steel

NASA Astrophysics Data System (ADS)

Kovalev, A. I.; Mishina, V. P.; Wainstein, D. L.; Titov, V. I.; Moiseev, V. F.; Tolochko, N. K.

2002-10-01

Presented is positive experience from selective laser sintering (SLS) of cylindrical steel specimens (3.0% C, 3.0% Cr, 1.0% Si, 12.0% V, Fe balance) 30 mm long and 5 mm in diameter by rapid prototyping. It was demonstrated that monolithic steel material could be successfully fabricated by this technology. Differential thermal analysis (DTA), scanning electron microscopy (SEM), and x-ray diffractometry (XRD) were used to study the microstructure, phase, and chemical composition of the source material and obtained specimens. Low-melting cementite-based eutectic was found to provide the liquid phase sintering of powder tool steel. The porosity of the green sintered specimens did not exceed 5%. The mean hardness value of sintered specimens was 825 HV.

Degradation of 4-Chlorophenol Under Sunlight Using ZnO Nanoparticles as Catalysts

NASA Astrophysics Data System (ADS)

Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Sherazi, Tufail H.; Kumar, Raj

2018-03-01

Herein we demonstrate a simplistic microwave assisted chemical precipitation approach regarding the synthesis of zinc oxide nanoparticles. As-prepared ZnO nanoparticles (NPs) were characterized by UV-visible spectroscopy, Fourier transform infra-red spectroscopy, atomic force microscopy and x-ray diffractometry and scrutinized as photo-catalysts for degradation of 4-chlorophenol (4-CP) under sunlight. The study substantiated that 98.5% of 4-CP was degraded within 20 min in the absence of initiator like H2O2 which reflects an outstanding prospective use for ZnO NPs as photo-catalysts. The nanocatalysts were recycled four times and still showed catalytic efficiency up to 95.5% for degradation of 4-CP in the specified 20 min.

Electric property measurement of free-standing SrTiO3 nanoparticles assembled by dielectrophoresis

NASA Astrophysics Data System (ADS)

Budiman, Faisal; Kotooka, Takumi; Horibe, Yoichi; Eguchi, Masanori; Tanaka, Hirofumi

2018-06-01

Free-standing strontium titanate (SrTiO3/STO) nanoparticles (NPs) were synthesized by the sol–gel method. X-ray diffractometry revealed that the required minimum annealing temperature to synthesize pure and highly crystalline STO NPs was 500 °C. Moreover, morphological observation by field emission scanning electron microscopy showed that the STO NPs have a spherical structure and their size depended on annealing condition. Electrical properties were measured using a low-temperature probing system. Here, an electrode was fabricated by electron beam lithography and the synthesized STO NPs were aligned at the electrodes by dielectrophoresis. The conductance of a sample was proportional to temperature. Two conduction mechanisms originating from hopping and tunneling appeared in the Arrhenius plot.

Structural, Optical and Electrical Properties of ITO Thin Films

NASA Astrophysics Data System (ADS)

Sofi, A. H.; Shah, M. A.; Asokan, K.

2018-02-01

Transparent and conductive thin films of indium tin oxide were fabricated on glass substrates by the thermal evaporation technique. Tin doped indium ingots with low tin content were evaporated in vacuum (1.33 × 10-7 kpa) followed by an oxidation for 15 min in the atmosphere in the temperature range of 600-700°C. The structure and phase purity, surface morphology, optical and electrical properties of thin films were studied by x-ray diffractometry and Raman spectroscopy, scanning electron microcopy and atomic force microscopy, UV-visible spectrometry and Hall measurements in the van der Pauw configuration. The x-ray diffraction study showed the formation of the cubical phase of polycrystalline thin films. The morphological analysis showed the formation of ginger like structures and the energy dispersive x-ray spectrum confirmed the presence of indium (In), tin (Sn) and oxygen (O) elements. Hall measurements confirmed n-type conductivity of films with low electrical resistivity ( ρ) ˜ 10-3 Ω cm and high carrier concentration ( n) ˜ 1020 cm-3. For prevalent scattering mechanisms in the films, experimental data was analyzed by calculating a mean free path ( L) using a highly degenerate electron gas model. Furthermore, to investigate the performance of the deposited films as a transparent conductive material, the optical figure of merit was obtained for all the samples.

Effect of hydrodynamics and surface roughness on the electrochemical behaviour of carbon steel in CSG produced water

NASA Astrophysics Data System (ADS)

Eyu, Gaius Debi; Will, Geoffrey; Dekkers, Willem; MacLeod, Jennifer

2015-12-01

The influence of fluid flow, surface roughness and immersion time on the electrochemical behaviour of carbon steel in coal seam gas produced water under static and hydrodynamic conditions has been studied. The disc electrode surface morphology before and after the corrosion test was characterized using scanning electron microscopy (SEM). The corrosion product was examined using X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD).The results show that the anodic current density increased with increasing surface roughness and consequently a decrease in corrosion surface resistance. Under dynamic flow conditions, the corrosion rate increased with increasing rotating speed due to the high mass transfer coefficient and formation of non-protective akaganeite β-FeO(OH) and goethite α-FeO(OH) corrosion scale at the electrode surface. The corrosion rate was lowest at 0 rpm. The corrosion rate decreased in both static and dynamic conditions with increasing immersion time. The decrease in corrosion rate is attributed to the deposition of corrosion products on the electrode surface. SEM results revealed that the rougher surface exhibited a great tendency toward pitting corrosion.

RADIOACTIVITY DOSAGE OF ORNAMENTAL GRANITIC ROCKS BASED ON CHEMICAL, MINERALOGICAL AND LITHOLOGICAL DATA

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

Salas, H.T.; Nalini, H.A. Jr.; Mendes, J.C.

2004-10-03

One hundred samples of granitic rock were collected from granite traders in Belo Horizonte. Autoradiography, optical microscopy, diffractometry, and chemical analysis (X-ray spectrometry, X-ray fluorescence, neutron activation, gravimetry and electron probe microanalysis) were used to determine the mineral assemblages and lithotypes. Autoradiographic results for several samples showed the presence of monazite, allanite and zircon. Chemical analysis revealed concentrations of uranium of {le} 30ppm, and thorium {le} 130ppm. Higher concentrations generally correlated with high concentrations of light rare earths in silica-rich rocks of granitic composition. Calculations were made of radioactive doses for floor tiles in a standard room for samples withmore » total concentration of uranium and thorium greater than 60ppm. On the basis of calculations of {sup 232}Th, {sup 40}K and {sup 226}Ra from Th, K and U analysis, the doses calculated were between 0.11 and 0.34 mSv/year, which are much lower than the acceptable international exposure standard of 1.0 mSv/year.« less

Method for improve x-ray diffraction determinations of residual stress in nickel-base alloys

DOEpatents

Berman, Robert M.; Cohen, Isadore

1990-01-01

A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys which comprises covering part of a predetermined area of the surface of a nickel-base alloy with a dispersion, exposing the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample.

Marble protection: An inorganic electrokinetic approach

NASA Astrophysics Data System (ADS)

Meloni, Paola; Manca, Francesco; Carcangiu, Gianfranco

2013-05-01

The influence of an electric potential difference in an aqueous solution was studied as a method for depositing a calcium oxalate coating over a weathered carbonatic stone. Samples of weathered Carrara white marble were treated at 15 and 50 °C for 5 h in an electrokinetic cell, specifically conceived for this study, containing a solution of ammonium oxalate (4% by weight), and were subsequently characterised by scanning electron microscopy, X-ray diffractometry, thermogravimetric analysis and mercury intrusion porosimetry. The electrokinetic treatment proved to be a cost effective and time saving process, able to produce a thick and homogeneous calcium oxalate coating over the stone surface that improves its chemical and physical resistance in low pH environments, and is able to protect the stone from the by-products of urban pollution.

A facile and efficient strategy for the fabrication of porous linseed gum/cellulose superabsorbent hydrogels for water conservation.

PubMed

Zhang, Hao; Luan, Qian; Huang, Qingde; Tang, Hu; Huang, Fenghong; Li, Wenlin; Wan, Chuyun; Liu, Changsheng; Xu, Jiqu; Guo, Pingmei; Zhou, Qi

2017-02-10

The linseed gum/cellulose composite hydrogels were successfully fabricated by mixing cellulose and linseed gum solutions dissolved in the NaOH/urea aqueous system and cross-linked with epichlorohydrin. The morphology and structure of the composite hydrogels were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). The swelling ratio and water retention properties were investigated. The results revealed that linseed gum mainly contributed to water adsorption, whereas the cellulose acted as a backbone to strengthen the porous structure. This work provided a simple way to prepare cellulose-based superabsorbent hydrogels, which could be potentially applied as an effective water conservation material in agriculture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of calcium phosphate coatings deposited by Nd:YAG laser ablation at 355 nm: influence of thickness.

PubMed

Fernández-Pradas, J M; Clèries, L; Sardin, G; Morenza, J L

2002-05-01

Calcium phosphate coatings were deposited by pulsed laser ablation with a radiation of 355 nm from a Nd:YAG laser. All the coatings were obtained at the same conditions, but deposition was stopped after different number of pulses to get coatings with different thickness. The influence of thickness in the structural and mechanical properties of the coatings was investigated. Coatings structure was characterised by scanning electron microscopy, grazing incidence X-ray diffractometry and Raman spectroscopy. The mechanical properties were evaluated by scratch test. The morphology of the coatings is dominated by the presence of droplets. The coatings are composed mainly of hydroxyapatite, alpha tricalcium phosphate and amorphous calcium phosphate. Thinner coatings withstand higher loads of failure in the scratch test.

Synthesis of core-shell structured FAU/SBA-15 composite molecular sieves and their performance in catalytic cracking of polystyrene

NASA Astrophysics Data System (ADS)

Du, Jinlong; Shi, Chunwei; Wu, Wenyuan; Bian, Xue; Chen, Ping; Cui, Qingzhu; Cui, Zhixuan

2017-12-01

Composite molecular sieves, FAU/SBA-15, having core-shell structure were synthesized. The synthesized composite sieves were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), pyrolysis fourier transform infrared (Py-FTIR) spectroscopy, temperature programmed desorption spectra (NH3-TPD), UV Raman spectroscopy, nuclear magnetic resonance (NMR) and other techniques. XRD, SEM, TEM, N2 adsorption-desorption, mass spectrometry, NMR and EDS results showed that the composite molecular sieve contained two pore channels. Py-FTIR results showed that the addition of HY molecular sieves improved the acidity of the composite zeolite. The crystallization mechanism during the growth of FAU/SBA-15 shell was deduced from the influence of crystallization time on the synthesis of FAU/SBA-15 core-shell structured composite molecular sieve. HY dissociated partially in H2SO4 solution, and consisted of secondary structural units. This framework structure was more stable than its presence in the isolated form on the same ring or in the absence of Al. Thus it played a guiding role and connected with SBA-15 closely through the Si-O bond. This resulted in the gradual covering of the exterior surface of FAU phase by SBA-15 molecular sieves. The presence of SBA-15 restricted the formation of the other high mass components and increased the selectivity towards ethylbenzene.

Soft chemistry routes for synthesis of rare earth oxide nanoparticles with well defined morphological and structural characteristics

NASA Astrophysics Data System (ADS)

Mancic, L.; Marinkovic, B. A.; Marinkovic, K.; Dramicanin, M.; Milosevic, O.

2011-11-01

Phosphors of (Y0.75Gd0.25)2O3:Eu3+ (5 at.%) have been prepared through soft chemistry routes. Conversion of the starting nitrates mixture into oxide is performed through two approaches: (a) hydrothermal treatment (HT) at 200 °C/3 h of an ammonium hydrogen carbonate precipitated mixture and (b) by thermally decomposition of pure nitrate precursor solution at 900 °C in dispersed phase (aerosol) within a tubular flow reactor by spray pyrolysis process (SP). The powders are additionally thermally treated at different temperatures: 600, 1000, and 1100 °C for either 3 or 12 h. HT—derived particles present exclusively one-dimensional morphology (nanorods) up to the temperatures of 600 °C, while the leaf-like particles start to grow afterward. SP—derived particles maintain their spherical shape up to the temperatures of 1100 °C. These submicron sized spheres were actually composed of randomly aggregated nanoparticles. All powders exhibits cubic Ia- 3 structure (Y0.75Gd0.25)2O3:Eu and have improved optical characteristics due to their nanocrystalline nature. The detailed study of the influence of structural and morphological powder characteristics on their emission properties is performed based on the results of X-ray powder diffractometry, scanning electron microscopy, X-ray energy dispersive spectroscopy, transmission electron microscopy, and photoluminescence measurements.

Ultrastructure of selected struvite-containing urinary calculi from dogs.

PubMed

Domingo-Neumann, R A; Ruby, A L; Ling, G V; Schiffman, P S; Johnson, D L

1996-09-01

To elucidate the ultrastructural details of struvite-containing urinary calculi from dogs. 38 specimens were selected from a collection of approximately 13,000 canine urinary calculi: 18 of these were composed entirely of struvite, and 20 consisted of struvite and calcium phosphate (apatite). Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron microprobe analysis. 4 textural types were recognized among struvite calculi, and 4 textural types of struvite-apatite calculi were described. Evidences of calculus dissolution were described from 4 calculi studied. The presence of small, well interconnected primary pores in struvite-containing urinary calculi from dogs appears to be a significant factor in determining the possible interaction of calculi with changes in the urine composition. The progress of dissolution from the calculus surface to the calculus interior appears to be largely affected by the primary porosity originally present between crystals forming the calculus framework. Apatite was observed to be more resistant to dissolution than struvite. The prevalence of fine concentric laminations having low porosity, and the common occurrence of apatite among struvite-containing urinary calculi from dogs may be 2 reasons why the efficacy of dietary and medicinal manipulations in dissolving urinary calculi is greater among cats than it is among dogs.

Morphological characterization and in vitro biocompatibility of a porous nickel-titanium alloy.

PubMed

Prymak, Oleg; Bogdanski, Denise; Köller, Manfred; Esenwein, Stefan A; Muhr, Gert; Beckmann, Felix; Donath, Tilmann; Assad, Michel; Epple, Matthias

2005-10-01

Disks consisting of macroporous nickel-titanium alloy (NiTi, Nitinol, Actipore) are used as implants in clinical surgery, e.g. for fixation of spinal dysfunctions. The morphological properties were studied by scanning electron microscopy (SEM) and by synchrotron radiation-based microtomography (SRmuCT). The composition was studied by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and energy-dispersive X-ray spectroscopy (EDX). The mechanical properties were studied with temperature-dependent dynamical mechanical analysis (DMA). Studies on the biocompatibility were performed by co-incubation of porous NiTi samples with isolated peripheral blood leukocyte fractions (polymorphonuclear neutrophil granulocytes, PMN; peripheral blood mononuclear leukocytes, PBMC) in comparison with control cultures without NiTi samples. The cell adherence to the NiTi surface was analyzed by fluorescence microscopy and scanning electron microscopy. The activation of adherent leukocytes was analyzed by measurement of the released cytokines using enzyme-linked immunosorbent assay (ELISA). The cytokine response of PMN (analyzed by the release of IL-1ra and IL-8) was not significantly different between cell cultures with or without NiTi. There was a significant increase in the release of IL-1ra (p<0.001), IL-6 (p<0.05), and IL-8 (p<0.05) from PBMC in the presence of NiTi samples. In contrast, the release of TNF-alpha by PBMC was not significantly elevated in the presence of NiTi. IL-2 was released from PBMC only in the range of the lower detection limit in all cell cultures. The material, clearly macroporous with an interconnecting porosity, consists of NiTi (martensite; monoclinic, and austenite; cubic) with small impurities of NiTi2 and possibly NiC(x). The material is not superelastic upon manual compression and shows a good biocompatibility.

Analysis of microstructure and mechanical properties of aluminium-copper joints welded by FSW process

NASA Astrophysics Data System (ADS)

Iordache, M.; Sicoe, G.; Iacomi, D.; Niţu, E.; Ducu, C.

2017-08-01

The research conducted in this article aimed to check the quality of joining some dissimilar materials Al-Cu by determining the mechanical properties and microstructure analysis. For the experimental measurements there were used tin alloy Al - EN-AW-1050A with a thickness of 2 mm and Cu99 sheet with a thickness of 2 mm, joined by FSW weld overlay. The main welding parameters were: rotating speed of the rotating element 1400 rev/min, speed of the rotating element 50 mm/min. The experimental results were determined on samples specially prepared for metallographic analysis. In order to prepare samples for their characterization, there was designed and built a device that allowed simultaneous positioning and fixing for grinding. The characteristics analyzed in the joint welded samples were mictrostructure, microhardness and residual stresses. The techniques used to determine these characteristics were optical microscopy, electron microscopy with fluorescence radioactive elemental analysis (EDS), Vickers microhardness line - HV0.3 and X-ray diffractometry.

Solid-State Characterization of Novel Propylene Glycol Ester Solvates Isolated from Lipid Formulations.

PubMed

Chakravarty, Paroma; Kothari, Sanjeev; Deese, Alan; Lubach, Joseph W

2015-07-06

The purpose of this study was to identify and characterize precipitates obtained from a liquid formulation of GNE068.HCl, a Genentech developmental compound, and lipophilic excipients, such as propylene glycol monocaprylate, and monolaurate. Precipitates were characterized using powder X-ray diffractometry (PXRD), differential scanning calorimetry, thermogravimetry, microscopy, nuclear magnetic resonance spectroscopy (NMR; solution and solid-state) and water sorption analysis. PXRD and NMR revealed the precipitates to be crystalline solvates of propylene glycol esters. The solvates (capryolate and lauroglycolate) were isomorphic and stable up to 70 °C, beyond which melting of the lattice occurred with subsequent dissolution of the active ingredient in the melt (microscopy and variable temperature PXRD). They were found to be mechanically stable (no change in PXRD pattern upon compression) and were nonhygroscopic up to ∼70% RH (25 °C). Our results highlight the outcome of inadvertent drug-excipient interactions in two separate lipid solution formulations with good solid-state properties and, thus, potential for further development.

Heteroepitaxial growth of Ge films on (100) GaAs by pyrolysis of digermane

NASA Astrophysics Data System (ADS)

Eres, Djula; Lowndes, Douglas H.; Tischler, J. Z.; Sharp, J. W.; Geohegan, D. B.; Pennycook, S. J.

1989-08-01

Pyrolysis of high-purity digermane (Ge2 H6 ) has been used to grow epitaxial Ge films of high crystalline quality on (100) GaAs substrates in a low-pressure environment. X-ray double-crystal diffractometry shows that fully commensurate, coherently strained epitaxial Ge films can be grown on (100) GaAs at digermane partial pressures of 0.05-40 mTorr for substrate temperatures of 380-600 °C. Amorphous films also were deposited. Information about the crystalline films surface morphology, growth mode, and microstructure was obtained from scanning electron microscopy, cross-section transmission electron microscopy, and in situ reflectivity measurements. The amorphous-to-crystalline transition temperature and the morphology of the crystalline films were both found to depend on deposition conditions (primarily the incidence rate of Ge-bearing species and the substrate temperature). Epitaxial growth rates using digermane were found to be about two orders of magnitude higher than rates using germane (GeH4 ) under similar experimental conditions.

Microwave combustion synthesis of Co1-xZnxFe2O4 (0⩽x⩽0.5): Structural, magnetic, optical and vibrational spectroscopic studies.

PubMed

Sundararajan, M; Kennedy, L John; Vijaya, J Judith; Aruldoss, Udaya

2015-04-05

Nanostructured pure and zinc doped cobalt ferrites (Co1-xZnxFe2O4 where x fraction ranging from 0 to 0.5) were prepared by microwave combustion method employing urea as a fuel. The nanostructured samples were characterized by using various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy, energy dispersive X-ray analysis, UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy and Fourier transformed infrared (FT-IR) spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis and the FT-IR spectroscopy revealed the formation of cobalt ferrite cubic spinel-type structure. The average crystallite sizes for the samples were in the range of 3.07-11.30 nm. The direct band gap (Eg) was estimated using Kubelka-Munk method and is obtained from the UV-vis spectra. The band gap value decreased with an increase in zinc fraction (2.56-2.17 eV). The violet and green emission observed in the photoluminescence spectra revealed that cobalt ferrites are governed by defect controlled processes. The elemental analysis of zinc doped cobalt ferrites were obtained from energy dispersive X-ray (EDX) analysis. From the magnetic measurements, it is observed that cobalt ferrite and zinc doped cobalt ferrite systems fall under the soft ferrite category. The saturation magnetization (Ms) value of undoped cobalt ferrite is 14.26 emu/g, and it has reached a maximum of 29.61 emu/g for Co0.7Zn0.3Fe2O4. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7) alloy powders by mechanical alloying

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

Maulik, Ornov; Kumar, Vinod, E-mail: vkt.meta@mnit.ac.in; Adjunct Faculty, Materials Research Centre, Malaviya National Institute of Technology, Jaipur 302017

2015-12-15

Novel AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7 mol) high-entropy alloys (HEAs) were synthesized by mechanical alloying. The effect of Mg content on the phase evolution of HEAs was investigated using X-Ray diffractometry (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern analysis. The particle morphology and composition of HEAs were investigated by scanning electron microscopy (SEM). Thermodynamic parameters were calculated and analyzed to explain the formation of a solid solution. XRD analysis revealed BCC as major phase and FCC as a minor phase in as-milled AlFeCuCr and AlFeCuCrMg{sub 0.5} HEAs. Also, XRD analysis of as-milledmore » AlFeCuCrMg, AlFeCuCrMg{sub 1.7} confirmed the formation of two BCC phases (BCC 1 and BCC 2). TEM–SAED analysis of AlFeCuCrMg{sub x} HEAs concurred with XRD results. Microstructural features and mechanism for solid solution formation have been conferred in detail. Phase formation of the present HEAs has been correlated with calculated thermodynamic parameters. Differential thermal analysis (TGA-DTA) of these alloys confirmed that there is no substantial phase change up to 500 °C. - Highlights: • Novel AlFeCuCrMg{sub x} (x = 0, 0.5, 1, 1.7) HEAs were prepared by mechanical alloying. • Phase evolution and lattice parameter were studied by X-Ray Diffraction. • Crystallite size and lattice microstrain calculated failed to obey the Williamson–Hall method. • Criterions for formation of simple solid solution were compared to the thermodynamic parameters of the present HEAs. • Increase in the Mg concentration in AlMg{sub x}FeCuCr (x = 0, 0.5, 1, 1.7) HEAs supports the formation of BCC phase.« less

X-ray diffraction characterization of epitaxial CVD diamond films with natural and isotopically modified compositions

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

Prokhorov, I. A., E-mail: igor.prokhorov@mail.ru; Voloshin, A. E.; Ralchenko, V. G.

2016-11-15

Comparative investigations of homoepitaxial diamond films with natural and modified isotopic compositions, grown by chemical vapor deposition (CVD) on type-Ib diamond substrates, are carried out using double-crystal X-ray diffractometry and topography. The lattice mismatch between the substrate and film is precisely measured. A decrease in the lattice constant on the order of (Δa/a){sub relax} ∼ (1.1–1.2) × 10{sup –4} is recorded in isotopically modified {sup 13}C (99.96%) films. The critical thicknesses of pseudomorphic diamond films is calculated. A significant increase in the dislocation density due to the elastic stress relaxation is revealed by X-ray topography.

Investigation on microstructure and mechanical properties of Mo2FeB2 based cermets with and without PVA

NASA Astrophysics Data System (ADS)

Shen, Yupeng; Huang, Zhifu; Jian, Yongxin; Yang, Ming; Li, Kemin

2018-03-01

Mo2FeB2 based cermets with and without PVA have been investigated by x-ray diffractometry (XRD), x-ray photoelectron spectroscope (XPS) and scanning electron microscopy (SEM). The density and transverse rupture strength (TRS) of green compact, relative density, hardness (HRA), fracture toughness (KIC) and TRS of Mo2FeB2 based cermets were also measured. The results indicate that, compared with the Mo2FeB2 based cermets without PVA, the density of green compact with PVA can be improved slightly at the same pressure. However, the much higher TRS is obtained for the green compact without PVA. Meanwhile, Mo2FeB2 particles exhibit the finer and less congruity feature for Mo2FeB2 based cermets without PVA. In addition, the higher relative density, hardness, fracture toughness and TRS can be acquired for the cermets without PVA. Obviously, considering the mechanical properties and preparation period of Mo2FeB2 based cermets, no adding PVA is the optimized process of powder molding in the manufacture of Mo2FeB2 based cermets.

Preparation of MWCNT-Fe3O4 Nanocomposites from Iron Sand Using Sonochemical Route

NASA Astrophysics Data System (ADS)

Rahmawati, R.; Melati, A.; Taufiq, A.; Sunaryono; Diantoro, M.; Yuliarto, B.; Suyatman, S.; Nugraha, N.; Kurniadi, D.

2017-05-01

The composites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sand were successfully prepared via the sonochemical route. In this experiment, the MWCNT-Fe3O4 nanocomposites were prepared with different compositions of MWCNT (0.01%, 0.02%, and 0.04%) with the constant composition of Fe3O4 particles. The characterizations were performed by means of X-Ray Diffractometry (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer and Scanning Electron Microscopy (SEM) integrated with Energy Dispersive X-Ray (EDX). The XRD data analysis showed that the Fe3O4 crystallize in spinel structure in nanometric size. Furthermore, the crystallinity of the samples tended to reduce by increasing the MWCNT compositions. The SEM images showed that Fe3O4 tend to agglomerate in nanometric size. The FTIR spectra detected the functional groups of Fe-O bonding that showed the existence of Fe2+ and Fe3+. In the composites, the Fe3O4 nanoparticles were physically mixed with the MWCNTs constructing a unique structure. The as prepared MWCNT-Fe3O4 nanocomposites have the potential for bio-applications.

Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

NASA Astrophysics Data System (ADS)

Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

2015-08-01

Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H2SO4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO2 particles. The results obtained show that addition of ZrO2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO2 addition, combination of high hardness of Ti2Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

Pulse electrodeposition of self-lubricating Ni-W/PTFE nanocomposite coatings on mild steel surface

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Kalaignan, G. Paruthimal; Anthuvan, J. Tennis

2015-12-01

Ni-W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni-W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni-W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni-W/PTFE nanocomposite coating has better corrosion resistance than the Ni-W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni-W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

Ion-induced crystal damage during plasma-assisted MBE growth of GaN layers

NASA Astrophysics Data System (ADS)

Kirchner, V.; Heinke, H.; Birkle, U.; Einfeldt, S.; Hommel, D.; Selke, H.; Ryder, P. L.

1998-12-01

Gallium nitride layers were grown by plasma-assisted molecular-beam epitaxy on (0001)-oriented sapphire substrates using an electron cyclotron resonance (ECR) and a radio frequency (rf) plasma source. An applied substrate bias was varied from -200 to +250 V, resulting in a change of the density and energy of nitrogen ions impinging the growth surface. The layers were investigated by high-resolution x-ray diffractometry and high-resolution transmission electron microscopy (HRTEM). Applying a negative bias during growth has a marked detrimental effect on the crystal perfection of the layers grown with an ECR plasma source. This is indicated by a change in shape and width of (0002) and (202¯5) reciprocal lattice points as monitored by triple axis x-ray measurements. In HRTEM images, isolated basal plane stacking faults were found, which probably result from precipitation of interstitial atoms. The crystal damage in layers grown with a highly negative substrate bias is comparable to that observed for ion implantation processes at orders of magnitude larger ion energies. This is attributed to the impact of ions on the growing surface. None of the described phenomena was observed for the samples grown with the rf plasma source.

Gold Nanoparticles: An Efficient Antimicrobial Agent against Enteric Bacterial Human Pathogen

PubMed Central

Shamaila, Shahzadi; Zafar, Noshin; Riaz, Saira; Sharif, Rehana; Nazir, Jawad; Naseem, Shahzad

2016-01-01

Enteric bacterial human pathogens, i.e., Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Klebsiella pneumoniae, are the major cause of diarrheal infections in children and adults. Their structure badly affects the human immune system. It is important to explore new antibacterial agents instead of antibiotics for treatment. This project is an attempt to explain how gold nanoparticles affect these bacteria. We investigated the important role of the mean particle size, and the inhibition of a bacterium is dose-dependent. Ultra Violet (UV)-visible spectroscopy revealed the size of chemically synthesized gold nanoparticle as 6–40 nm. Atomic force microscopy (AFM) analysis confirmed the size and X-ray diffractometry (XRD) analysis determined the polycrystalline nature of gold nanoparticles. The present findings explained how gold nanoparticles lyse Gram-negative and Gram-positive bacteria. PMID:28335198

Gold leaf counter electrodes for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Shimada, Kazuhiro; Toyoda, Takeshi

2018-03-01

In this study, a gold leaf 100 nm thin film is used as the counter electrode in dye-sensitized solar cells. The traditional method of hammering gold foil to obtain a thin gold leaf, which requires only small amounts of gold, was employed. The gold leaf was then attached to the substrate using an adhesive to produce the gold electrode. The proposed approach for fabricating counter electrodes is demonstrated to be facile and cost-effective, as opposed to existing techniques. Compared with electrodes prepared with gold foil and sputtered gold, the gold leaf counter electrode demonstrates higher catalytic activity with a cobalt-complex electrolyte and higher cell efficiency. The origin of the improved performance was investigated by surface morphology examination (scanning electron microscopy), various electrochemical analyses (cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy), and crystalline analysis (X-ray diffractometry).

Characterization of home-made silver sulphide based iodide selective electrode.

PubMed

Rajbhandari Nyachhyon, A; Yadav, A P; Manandhar, K; Pradhananga, R R

2010-09-15

Polycrystalline silver sulphide/silver iodide ion selective electrodes (ISEs) with four different compositions, 9:1, 2:1, 1:1, 1:9 Ag(2)S-AgI mole ratios, have been fabricated in the laboratory and characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). X-ray diffraction studies show the presence of Ag(3)SI, Ag(2)S and AgI crystalline phases in the electrode material. The electrode surfaces have been found to become smoother and lustrous with increasing percentage of silver sulphide in silver iodide. ISE 1:1, ISE 2:1 and ISE 9:1 all responded in Nernstian manner with slopes of about 60 mV/decade change in iodide ion concentration in the linear range of 1 x 10(-1) to 1 x 10(-6)M while ISE 1:9 showed sub-Nernstian behavior with slope of about 45 mV up to the concentration 1 x 10(-5)M. Two capacitive loops, one corresponding to the charge transfer process at metal electrode and the back contact and a second loop corresponding to the charge transfer process at membrane-electrolyte interface have been observed at high and low frequency ranges, respectively. Mott-Schottky analysis shows that the materials are n-type semiconductors with donor defect concentrations in the range of 5.1 x 10(14) to 2.4 x 10(19)/cm(3). Copyright (c) 2010 Elsevier B.V. All rights reserved.

Method for improving x-ray diffraction determinations of residual stress in nickel-base alloys

DOEpatents

Berman, R.M.; Cohen, I.

1988-04-26

A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys is discussed. Part of a predetermined area of the surface of a nickel-base alloy is covered with a dispersion. This exposes the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose, since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample. 2 figs.

Strength Characteristics of Resorbable Osteoconductive Ceramics Based on Diphosphates of Calcium and Alkali Metals

NASA Astrophysics Data System (ADS)

Putlayev, V. I.; Evdokimov, P. V.; Garshev, A. V.; Prosvirin, D. V.; Klimashina, E. S.; Safronova, T. V.; Ivanov, V. K.

2014-02-01

An investigation into the strength characteristics of ceramics based on diphosphates Ca(3- x)М2 x (PO4)2 ( x = 0-1 and М = Na, K) provides evidence of composition strengthening in the range х = 0.6-0.8 containing the greatest amount of the supercooled high-temperature modification α-СаМРО4. The method of high-temperature x-ray diffractometry is used to examine thermal expansion of rhenanite phases of СаМРО4.

Thin calcium phosphate coatings on titanium by electrochemical deposition in modified simulated body fluid.

PubMed

Peng, Ping; Kumar, Sunil; Voelcker, Nicolas H; Szili, Endre; Smart, Roger St C; Griesser, Hans J

2006-02-01

Adherent and optically semitransparent thin calcium phosphate (CaP) films were electrochemically deposited on titanium substrates in a modified simulated body fluid at 37 degrees C. Coatings deposited by using periodic pulsed potentials showed better adhesion and better mechanical properties than coatings deposited with use of a constant potential. Scanning electron microscopy was used to study the morphology of the coatings. The coatings displayed a polydispersed porous structure with pores in the range of a few nanometers to 1 mum. Furthermore, X-ray diffractometry and the O(1s) satellite peaks in X-ray photoelectron spectroscopy indicated that the coatings possessed a similar surface chemistry to that of natural bone minerals. These results were confirmed by inductively coupled plasma optical emission spectrometry, which yielded a Ca:P ratio of 1.65, close to that of hydroxyapatite. Contact mode atomic force microscopy (AFM) showed the average thickness of the coatings was in the order of 200 nm. Root-mean-square (RMS) roughness values, also derived by AFM, were shown to be much higher on the titanium-CaP surfaces in comparison with untreated titanium substrates, with RMS values of about 300 and 110 nm, respectively. Cell culture experiments showed that the CaP surfaces are nontoxic to MG63 osteoblastic cells in vitro and were able to support cell growth for up to 4 days, outperforming the untreated titanium surface in a direct comparison. These easily prepared coatings show promise for hard-tissue biomaterials. (c) 2005 Wiley Periodicals, Inc.

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

Lan, Xiaodong; Wu, Hong, E-mail: wuhong927@126.com

Metallic glass composite coatings Ti{sub 45}Cu{sub 41}Ni{sub 9}Zr{sub 5} and Ti{sub 45}Cu{sub 41}Ni{sub 6}Zr{sub 5}Sn{sub 3} (at.%) on a Ti-30Nb-5Ta-7Zr (wt.%) (TNTZ) alloy were prepared by laser cladding. The microstructures of the coatings were characterized by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analyzer (EDXA), and transmission electron microscopy (TEM). Results indicated that the coatings have an amorphous structure embedded with a few nanocrystalline phases and dendrites. A partial substitution of Ni by Sn can improve the glass forming ability of Ti-base metallic glass system, and induce the formation of nano-sized Ni{sub 2}SnTimore » phase during the cyclic laser heating. The tribological behavior of both the substrate and the coatings was investigated in detail. A significant improvement in both the hardness and the wear resistance of the coatings was achieved with the addition of Sn. The relationship between the wear resistance and the microstructures of the coatings was discussed. - Highlights: •Ti-based metallic glass composite coatings were prepared by laser cladding. •The wear resistance is greatly improved by laser cladding of composite coatings. •Substitution of Ni by Sn increases GFA and wear resistance of the coatings. •A good balance of crystalline/amorphous phases improves the wear resistance. •Adhesive wear serves as the dominant wear mechanism of the composite coatings.« less

Synthesis of core–shell structured FAU/SBA-15 composite molecular sieves and their performance in catalytic cracking of polystyrene

PubMed Central

Du, Jinlong; Shi, Chunwei; Wu, Wenyuan; Bian, Xue; Chen, Ping; Cui, Qingzhu; Cui, Zhixuan

2017-01-01

Abstract Composite molecular sieves, FAU/SBA-15, having core-shell structure were synthesized. The synthesized composite sieves were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), pyrolysis fourier transform infrared (Py-FTIR) spectroscopy, temperature programmed desorption spectra (NH3-TPD), UV Raman spectroscopy, nuclear magnetic resonance (NMR) and other techniques. XRD, SEM, TEM, N2 adsorption-desorption, mass spectrometry, NMR and EDS results showed that the composite molecular sieve contained two pore channels. Py-FTIR results showed that the addition of HY molecular sieves improved the acidity of the composite zeolite. The crystallization mechanism during the growth of FAU/SBA-15 shell was deduced from the influence of crystallization time on the synthesis of FAU/SBA-15 core-shell structured composite molecular sieve. HY dissociated partially in H2SO4 solution, and consisted of secondary structural units. This framework structure was more stable than its presence in the isolated form on the same ring or in the absence of Al. Thus it played a guiding role and connected with SBA-15 closely through the Si-O bond. This resulted in the gradual covering of the exterior surface of FAU phase by SBA-15 molecular sieves. The presence of SBA-15 restricted the formation of the other high mass components and increased the selectivity towards ethylbenzene. PMID:29383044

Effect of milling atmosphere on structural and magnetic properties of Ni-Zn ferrite nanocrystalline

NASA Astrophysics Data System (ADS)

Hajalilou, Abdollah; Hashim, Mansor; Ebrahimi-Kahrizsangi, Reza; Masoudi Mohamad, Taghi

2015-04-01

Powder mixtures of Zn, NiO, and Fe2O3 are mechanically alloyed by high energy ball milling to produce Ni-Zn ferrite with a nominal composition of Ni0.36Zn0.64Fe2O4. The effects of milling atmospheres (argon, air, and oxygen), milling time (from 0 to 30 h) and heat treatment are studied. The products are characterized using x-ray diffractometry, field emission scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and transmitted electron microscopy. The results indicate that the desired ferrite is not produced during the milling in the samples milled under either air or oxygen atmospheres. In those samples milled under argon, however, Zn/NiO/Fe2O3 reacts with a solid-state diffusion mode to produce Ni-Zn ferrite nanocrystalline in a size of 8 nm after 30-h-milling. The average crystallite sizes decrease to 9 nm and 10 nm in 30-h-milling samples under air and oxygen atmospheres, respectively. Annealing the 30-h-milling samples at 600 °C for 2 h leads to the formation of a single phase of Ni-Zn ferrite, an increase of crystallite size, and a reduction of internal lattice strain. Finally, the effects of the milling atmosphere and heating temperature on the magnetic properties of the 30-h-milling samples are investigated. Project supported by the University Putra Malaysia Graduate Research Fellowship Section.

Spatial Distribution of Trehalose Dihydrate Crystallization in Tablets by X-ray Diffractometry.

PubMed

Thakral, Naveen K; Yamada, Hiroyuki; Stephenson, Gregory A; Suryanarayanan, Raj

2015-10-05

Crystallization of trehalose dihydrate (C12H22O11·2H2O) was induced by storing tablets of amorphous anhydrous trehalose (C12H22O11) at 65% RH (RT). Our goal was to evaluate the advantages and limitations of two approaches of profiling spatial distribution of drug crystallization in tablets. The extent of crystallization, as a function of depth, was determined in tablets stored for different time-periods. The first approach was glancing angle X-ray diffractometry, where the penetration depth of X-rays was modulated by the incident angle. Based on the mass attenuation coefficient of the matrix, the depth of X-ray penetration was calculated as a function of incident angle, which in turn enabled us to "calculate" the extent of crystallization to different depths. In the second approach, the tablets were split into halves and the split surfaces were analyzed directly. Starting from the tablet surface and moving toward the midplane, XRD patterns were collected in 36 "regions", in increments of 0.05 mm. The results obtained by the two approaches were, in general, in good agreement. Additionally, the results obtained were validated by determining the "average" crystallization in the entire tablet by using synchrotron radiation in the transmission mode. The glancing angle method could detect crystallization up to ∼650 μm and had a "surface bias". Being a nondestructive technique, this method will permit repeated analyses of the same tablet at different time points, for example, during a stability study. However, split tablet analyses, while a "destructive" technique, provided comprehensive and unbiased depth profiling information.

Gradient doping - a case study with Ti-Fe2O3 towards an improved photoelectrochemical response.

PubMed

Srivastav, Anupam; Verma, Anuradha; Banerjee, Anamika; Khan, Saif A; Gupta, Mukul; Satsangi, Vibha Rani; Shrivastav, Rohit; Dass, Sahab

2016-12-07

The present study investigates the effect of gradient doping on modifying the photoelectrochemical response of Ti-doped Fe 2 O 3 photoanodes for their use in sunlight based water splitting for hydrogen evolution. The deposition of a thin film over the ITO (tin doped indium oxide) substrate was carried out using a spray pyrolysis method. The concentration of dopant was varied from 0.5-8.0 at% and two sets of samples were also prepared with low to high (0.5-8%) and high to low (8-0.5%) dopant concentrations in the direction towards the substrate. The prepared thin films were characterized using X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS) and UV-visible Spectroscopy. The photoelectrochemical studies revealed that the deposition of dopant layers with a low to high concentration towards the substrate exhibited a highly improved photoresponse (200 times) in comparison to the pristine sample and a two fold enhancement in comparison to 2% Ti-doped Fe 2 O 3 . The improvement in the photoresponse has been attributed to the values of a high flat band potential, low resistance, high open circuit voltage, carrier separation efficiency, applied bias photon-to-current conversion efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). A reduced charge transfer resistance has been demonstrated with Nyquist plots.

Preparation and characterization of non-crystalline granular starch and corresponding carboxymethyl starch.

PubMed

Zhang, Bao; Li, Xiaomin; Xie, Qiutao; Tao, Han; Wang, Wu; Chen, Han-Qing

2017-10-01

Native corn starch slurried in 50% ethanol solution was treated at 60°C, 70°C, 80°C, and 85°C, respectively. The resultant starches were investigated by polarized microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The Maltese cross of ethanol-heating treated starch gradually weaken with increasing temperature and completely disappeared at 85°C. SEM data indicated the treated granular exhibited a rougher surface with more pores and grooves than native starch granular, but the shape of the treated starch was still intact. DSC and XRD data confirmed ethanol-heating treated starch changed from crystalline to non-crystalline structure at 85°C. The highest degree of substitution (DS) and corresponding reaction efficiency (RE) for the carboxymethylation of native starch were 0.66 and 36.7%, respectively, while the corresponding DS and RE for non-crystalline granular starches increased by 0.29 and 16.1% at the same reaction condition, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Review of Research Work on Ti-BASED Composite Coatings

NASA Astrophysics Data System (ADS)

Gabbitas, Brian; Salman, Asma; Zhang, Deliang; Cao, Peng

The service life of industrial components is limited predominantly by Chemical corrosion/mechanical wear. The project is concerned with the investigation of the capability of Ti(Al,O)/Al2O3 coatings to improve the service life of tool steel (H13) used for dies in aluminium high pressure die casting. This paper gives a general review on the research work conducted at the University of Waikato on producing and evaluating the titanium/alumina based composite coatings. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO2 powders in two different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity air-fuel (HVAF) technique on H13 steel substrates to produce a Ti(Al,O)/Al2O3 composite coatings. The performance of the coating was assessed in terms of thermal shock resistance and reaction kinetics with molten aluminium. The composite powders and coatings were characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD).

Different preparation methods and characterization of magnetic maghemite coated with chitosan

NASA Astrophysics Data System (ADS)

Hojnik Podrepšek, Gordana; Knez, Željko; Leitgeb, Maja

2013-06-01

The preparation of maghemite (γ-Fe2O3) micro- and nanoparticles coated with chitosan, used as carriers for immobilized enzymes, was investigated. γ-Fe2O3 nanoparticles were synthesized by coprecipitation of Fe2+ and Fe3+ ions in the presence of ammonium. They were coated with chitosan by the microemulsion process, suspension cross-linking technique, and covalent binding of chitosan on the γ-Fe2O3 surface. The methods distinguished the concentration of chitosan, concentration of acetic acid solution, concentration of a cross-linking agent, temperature of synthesis, pH of the medium, and time of synthesis. γ-Fe2O3 micro- and nanoparticles coated with chitosan prepared after three preparation methods were evaluated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy analysis, energy dispersive spectrometry, thermogravimetric analysis, differential scanning calorimetry analysis, vibrating sample magnetometry, dynamic light scattering, laser diffraction granulometry, and X-ray diffractometry. These positive attributes demonstrated that these magnetic micro- and nanoparticles coated with chitosan may be used as a promising carrier for further diverse biomedical applications.

Characterization and evaluation of miconazole salts and cocrystals for improved physicochemical properties.

PubMed

Tsutsumi, Shunichirou; Iida, Motoo; Tada, Norio; Kojima, Takashi; Ikeda, Yukihiro; Moriwaki, Toshiya; Higashi, Kenjirou; Moribe, Kunikazu; Yamamoto, Keiji

2011-12-15

Miconazole salts and cocrystals were studied to improve the physicochemical properties of miconazole. Maleate, hemifumarate, and hemisuccinate were prepared and characterized by powder X-ray diffractometry, differential scanning calorimetry, and single crystal X-ray diffractometry. The intrinsic dissolution rate and stability of each miconazole crystal form were compared to those of freebase and nitrate to evaluate the optimal crystal form. Crystal structure analysis indicated that maleate was a salt formed by proton transfer from the acid to the imidazole group of miconazole. Hemifumarate and hemisuccinate were determined to be cocrystals formed by hydrogen bonding between the acids and the base in their crystal lattices. Intrinsic dissolution tests showed that the formation of salts and cocrystals improved the dissolution rate of miconazole. Stability tests of preliminary formulations prepared with each crystal form indicated that maleate and hemifumarate were unstable at 80°C and generated a specific degraded product, i.e., a Michael adduct, between miconazole and the acids. Hemisuccinate had a superior intrinsic dissolution rate and stability, and is thus considered a promising crystal form of miconazole. Copyright © 2011 Elsevier B.V. All rights reserved.

X-ray microscopy of live biological micro-organisms

NASA Astrophysics Data System (ADS)

Raja Al-Ani, Ma'an Nassar

Real-time, compact x-ray microscopy has the potential to benefit many scientific fields, including microbiology, pharmacology, organic chemistry, and physics. Single frame x-ray micro-radiography, produced by a compact, solid-state laser plasma source, allows scientists to use x-ray emission for elemental analysis, and to observe biological specimens in their natural state. In this study, x-ray images of mouse kidney tissue, live bacteria, Pseudomonas aeruginosa and Burkholderia cepacia, and the bacteria's interaction with the antibiotic gentamicin, are examined using x-ray microscopy. For the purposes of comparing between confocal microscopy and x-ray microscopy, we introduced to our work the technique of gold labeling. Indirect immunofluorescence staining and immuno-gold labeling were applied on human lymphocytes and human tumor cells. Differential interference contrast microscopy (DIC) showed the lymphocyte body and nucleus, as did x-ray microscopy. However, the high resolution of x-ray microscopy allows us to differentiate between the gold particles bound to the antibodies and the free gold. A compact, tabletop Nd: glass laser is used in this study to produce x-rays from an Yttrium target. An atomic force microscope is used to scan the x-ray images from the developed photo-resist. The use of compact, tabletop laser plasma sources, in conjunction with x-ray microscopy, is a new technique that has great potential as a flexible, user-friendly scientific research tool.

Asbestiform minerals in ophiolitic rocks of Calabria (southern Italy).

PubMed

Campopiano, Antonella; Olori, Angelo; Spadafora, Alessandra; Rosaria Bruno, Maria; Angelosanto, Federica; Iannò, Antonino; Casciardi, Stefano; Giardino, Renato; Conte, Maurizio; Oranges, Teresa; Iavicoli, Sergio

2018-03-22

Ophiolitic rocks cropping on Calabria territory, southern Italy, can hold asbestiform minerals potentially harmful for human health. The aim of this work was to detect the fibrous phases of ophiolites along the Coastal Chain of northern Calabria and southern part of the Sila massif. Above 220 massive samples were collected in the study areas and analyzed using optical and electron microscopy, X-ray diffractometry, and Fourier transform infra-red spectrometry. The main fibrous constituent belonged to tremolite-actinolite series followed by fibrous antigorite that becomes more abundant in the samples collected in Reventino Mount surroundings. Results highlighted that serpentinites samples mainly consisted of antigorite and minor chrysotile. Samples collected along the coastal chain of northern Calabria did not hold fibrous materials. The results will be useful for Italian natural occurrences of asbestos (NOA) mapping in order to avoid an unintentional exposition by human activity or weathering processes.

Low Temperature Synthesis of Cobalt-Chromium Carbide Nanoparticles-Doped Carbon Nanofibers.

PubMed

Yousef, Ayman; Brooks, Robert M; Abutaleb, Ahmed; Al-Deyab, Salem S; El-Newehy, Mohamed H

2018-04-01

Electrospinning has been used to synthesize cobalt-chromium carbide nanoparticles (NPs)-doped carbon nanofibers (CNFs) (Composite). Electrospun mat comprising of cobalt acetate, chromium acetate and poly(vinyl alcohol) (PVA) has been carbonized at low temperature (850 °C) for 3 h under argon atmosphere to produce the introduced composite. The process was achieved at low temperature due to the presence of cobalt as an activator. Field emission scanning electron microscope (FE-SEM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) equipped with EDX techniques were used to determine the products characteristics. The results indicated the formation of pure cobalt (Co), Cr7C3 NPs and crystalline CNFs. The Co and Cr7C3 NPs were covered with CNFs. Overall, the proposed NFs open new avenue to prepare different metals-metal carbides-carbon NFs at low temperature and short reaction time.

Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

PubMed

Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

2015-06-01

Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Different decay patterns observed in a nineteenth-century building (Palma, Spain).

PubMed

Genestar, Catalina; Pons, Carmen; Cerro, José Carlos; Cerdà, Víctor

2014-01-01

The effects of atmospheric pollutants and climatic conditions were studied in a decayed column in the Seminary of Sant Pere. This nineteenth-century building is situated in the historic centre of Palma (Mallorca, Spain), less than 0.5 km from the sea. Samples were collected from the internal and external part of the crusts formed in the four sides of the column. The samples were analysed by means of thermal analysis, X-ray diffractometry, scanning electron microscopy, Fourier transform infrared spectroscopy and ion chromatography. Results show significant differences in the four sides of the column. A high degree of carbonate stone sulfation is observed in all of the samples analysed. A synergistic effect between atmospheric factors and micropollutants on the deterioration of stone is observed. A high uptake of atmospheric particulate matter is found in the external part of the black crusts.

The microstructure and tensile properties of extruded melt-spun ribbons of iron-rich B2 FeAl

NASA Technical Reports Server (NTRS)

Baker, I.; Gaydosh, D. J.

1987-01-01

The microstructure of extruded rods of iron-rich FeAl(B2-structure), as characterized by TEM, SEM, optical microscopy and x-ray diffractometry, consisted of elongated grains with a 111-line fibre texture containing a high dislocation density. Numerous oxide particles were found, mostly in lines which reflected the matrix flow during extrusion. In addition, some large inclusions were present. Tensile testing of annealed, relatively dislocation-free specimens as a function of increasing temperature found increasing ductility up to 900K, above which a ductility drop occurred accompanied by a change in fracture mode, from transgranular cleavage to intergranular fracture. The yield strength, which was independent of temperature up to 800K (at about 500MPa), also decreased rapidly as diffusion became more important. The predominant slip vector changed from 111-line to 100-line around 700K.

Synthesis of vaterite and aragonite crystals using biomolecules of tomato and capsicum

NASA Astrophysics Data System (ADS)

Chen, Long; Xu, Wang-Hua; Zhao, Ying-Guo; Kang, Yan; Liu, Shao-Hua; Zhang, Zai-Yong

2012-12-01

In this paper, biomimetic synthesis of calcium carbonate (CaCO3) in the presence of biomolecules of two vegetables-tomato and capsicum is investigated. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the CaCO3 obtained. The biomolecules in the extracts of two vegetables are determined by UV-vis or FTIR. The results indicate that a mixture of calcite and vaterite spheres constructed from small particles is produced with the extract of tomato, while aragonite rods or ellipsoids are formed in the presence of extract of capsicum. The possible formation mechanism of the CaCO3 crystals with tomato biomolecules can be interpreted by particle-aggregation based non-classical crystallization laws. The proteins and/or other biomolecules in tomato and capsicum may control the formation of vaterite and aragonite crystals by adsorbing onto facets of them.

Gold nanoparticle decorated multi-walled carbon nanotubes as counter electrode for dye sensitized solar cells.

PubMed

Kaniyoor, Adarsh; Ramaprabhu, Sundara

2012-11-01

A novel counter electrode material for dye sensitized solar cells (DSSCs) composed of nanostructured Au particles decorated on functionalized multi-walled carbon nanotubes (f-MWNTs) is demonstrated for the first time. MWNTs synthesized by catalytic chemical vapor deposition technique are purified and functionalized by treating with concentrated acids. Au nanoparticles are decorated on f-MWNTs by a rapid and facile microwave assisted polyol reduction method. The materials are characterized by X-ray diffractometry, Fourier transform infra red spectroscopy and electron microscopy. The DSSC fabricated with Au/f-MWNTs based counter electrode shows enhanced power conversion efficiency (eta) of 4.9% under AM 1.5G simulated solar radiation. In comparison, the reference DSSCs fabricated with f-MWNTs and Pt counter electrodes show eta of 2.1% and 4.5%. This high performance of Au/f-MWNTs counter electrode is investigated using electrochemical impedance spectroscopy and cyclic voltammetry studies.

Improvement in the Shape Memory Response of Ti50.5Ni24.5Pd25 High-Temperature Shape Memory Alloy with Scandium Microalloying

NASA Technical Reports Server (NTRS)

Atli, K. C.; Karaman, I; Noebe, R. D.; Garg, A.; Chumlyakov, Y. I.; Kireeva, I. V.

2010-01-01

A Ti(50.5)Ni(24.5)Pd25 high-temperature shape memory alloy (HTSMA) is microalloyed with 0.5 at. pct scandium (Sc) to enhance its shape-memory characteristics, in particular, dimensional stability under repeated thermomechanical cycles. For both Ti(50.5)Ni(24.5)Pd25 and the Sc-alloyed material, differential scanning calorimetry is conducted for multiple cycles to characterize cyclic stability of the transformation temperatures. The microstructure is evaluated using electron microscopy, X-ray diffractometry, and wavelength dispersive spectroscopy. Isobaric thermal cycling experiments are used to determine transformation temperatures, dimensional stability, and work output as a function of stress. The Sc-doped alloy displays more stable shape memory response with smaller irrecoverable strain and narrower thermal hysteresis than the baseline ternary alloy. This improvement in performance is attributed to the solid solution hardening effect of Sc.

Petro-mineralogical Studies of the Paleoproterozoic Phosphorites in the Sonrai basin, Lalitpur District, Uttar Pradesh, India

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

Dar, Shamim A., E-mail: sjshamim@gmail.com; Khan, K. F.; Khan, Saif A.

2015-09-15

The Paleoproterozoic phosphorites constitute an economically significant component of the Sonrai basin of Lalitpur district. These are associated with ferruginous shale, ironstone, limestone and quartz breccia. Petro-mineralogical studies of samples of the phosphorites, using X-ray diffractometry and scanning electron microscopy, reveal that the collophane (carbonate-fluorapatite) is the dominant phosphate mineral. Calcite, dolomite, quartz, mica and haematite are the dominant gangue constituents. The phosphate minerals occur as oolites mutually replaced by carbonate and silica. The presence of iron oxides has been found in most of the thin sections. There is meagre evidence of organic matter in the form of filaments ofmore » microbial phosphate laminae in the samples of phosphorite. The mineral assemblages, their texture and various forms in these phosphorites may be due to some environmental vicissitudes followed by replacement processes and biogenic activities.« less

Growth, structural, optical, thermal and mechanical properties of ammonium pentaborate single crystal.

PubMed

Balakrishnan, T; Bhagavannarayana, G; Ramamurthi, K

2008-11-15

Nonlinear optical single crystals of ammonium pentaborate (APB) were grown by the slow cooling method from aqueous solution. Grown crystal was characterized by powder X-ray diffraction (PXRD) and FT-IR spectral analysis. Perfection of the grown crystal was evaluated by high-resolution X-ray diffractometry (HRXRD). The effect of nylon threading on the perfection of the grown bigger crystal was also studied by HRXRD. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. Thermal properties were investigated by TG-DTA and DSC analyses. Its mechanical hardness was estimated by Vickers microhardness tester.

Pseudomorphic GeSiSn, SiSn and Ge layers in strained heterostructures

NASA Astrophysics Data System (ADS)

Timofeev, V. A.; Nikiforov, A. I.; Tuktamyshev, A. R.; Mashanov, V. I.; Loshkarev, I. D.; Bloshkin, A. A.; Gutakovskii, A. K.

2018-04-01

The GeSiSn, SiSn layer growth mechanisms on Si(100) were investigated and the kinetic diagrams of the morphological GeSiSn, SiSn film states in the temperature range of 150 °C-450 °C at the tin content from 0% to 35% were built. The phase diagram of the superstructural change on the surface of Sn grown on Si(100) in the annealing temperature range of 0 °C-850 °C was established. The specular beam oscillations were first obtained during the SiSn film growth from 150 °C to 300 °C at the Sn content up to 35%. The transmission electron microscopy and x-ray diffractometry data confirm the crystal perfection and the pseudomorphic GeSiSn, SiSn film state, and also the presence of smooth heterointerfaces between GeSiSn or SiSn and Si. The photoluminescence for the multilayer periodic GeSiSn/Si structures in the range of 0.6-0.8 eV was detected. The blue shift with the excitation power increase is observed suggesting the presence of a type II heterostructure. The creation of tensile strained Ge films, which are pseudomorphic to the underlying GeSn layer, is confirmed by the results of the formation and analysis of the reciprocal space map in the x-ray diffractometry. The tensile strain in the Ge films reached the value in the range of 0.86%-1.5%. The GeSn buffer layer growth in the Sn content range from 8% to 12% was studied. The band structure of heterosystems based on pseudomorphic GeSiSn, SiSn and Ge layers was calculated and the valence and conduction band subband position dependences on the Sn content were built. Based on the calculation, the Sn content range in the GeSiSn, SiSn, and GeSn layers, which corresponds to the direct bandgap GeSiSn, SiSn, and Ge material, was obtained.

Use of glancing angle X-ray powder diffractometry to depth-profile phase transformations during dissolution of indomethacin and theophylline tablets.

PubMed

Debnath, Smita; Predecki, Paul; Suryanarayanan, Raj

2004-01-01

The purpose of this study was (i) to develop glancing angle x-ray powder diffractometry (XRD) as a method for profiling phase transformations as a function of tablet depth; and (ii) to apply this technique to (a) study indomethacin crystallization during dissolution of partially amorphous indomethacin tablets and to (b) profile anhydrate --> hydrate transformations during dissolution of theophylline tablets. The intrinsic dissolution rates of indomethacin and theophylline were determined after different pharmaceutical processing steps. Phase transformations during dissolution were evaluated by various techniques. Transformation in the bulk and on the tablet surface was characterized by conventional XRD and scanning electron microscopy, respectively. Glancing angle XRD enabled us to profile these transformations as a function of depth from the tablet surface. Pharmaceutical processing resulted in a decrease in crystallinity of both indomethacin and theophylline. When placed in contact with the dissolution medium, while indomethacin recrystallized, theophylline anhydrate rapidly converted to theophylline monohydrate. Due to intimate contact with the dissolution medium, drug transformation occurred to a greater extent at or near the tablet surface. Glancing angle XRD enabled us to depth profile the extent of phase transformations as a function of the distance from the tablet surface. The processed sample (both indomethacin and theophylline) transformed more rapidly than did the corresponding unprocessed drug. Several challenges associated with the glancing angle technique, that is, the effects of sorbed water, phase transformations during the experimental timescale, and the influence of phase transformation on penetration depth, were addressed. Increased solubility, and consequently dissolution rate, is one of the potential advantages of metastable phases. This advantage is negated if, during dissolution, the metastable to stable transformation rate > dissolution rate. Glancing angle XRD enabled us to quantify and thereby profile phase transformations as a function of compact depth. The technique has potential utility in monitoring surface reactions, both chemical decomposition and physical transformations, in pharmaceutical systems.

Single Crystal Diffractometry

NASA Astrophysics Data System (ADS)

Arndt, U. W.; Willis, B. T. M.

2009-06-01

Preface; Acknowledgements; Part I. Introduction; Part II. Diffraction Geometry; Part III. The Design of Diffractometers; Part IV. Detectors; Part V. Electronic Circuits; Part VI. The Production of the Primary Beam (X-rays); Part VII. The Production of the Primary Beam (Neutrons); Part VIII. The Background; Part IX. Systematic Errors in Measuring Relative Integrated Intensities; Part X. Procedure for Measuring Integrated Intensities; Part XI. Derivation and Accuracy of Structure Factors; Part XII. Computer Programs and On-line Control; Appendix; References; Index.

The effect of X-ray exposure on Ba2SiO4:Eu3+

NASA Astrophysics Data System (ADS)

Volhard, Max-Fabian; Jüstel, Thomas

2018-03-01

The ortho-silicates Ba2SiO4:Eu3+ and Ba2SiO4:Eu2+ are well-established materials for fluorescent light sources, e.g., phosphor converted LEDs. Samples containing Eu2+or Eu3+were synthesised by the solid-state-method, and the phase purity was determined by X-ray powder diffractometry. The photoluminescence of both phosphors was examined as a function of the pre-treatment. Upon irradiation of Ba2SiO4:Eu3+ with X-rays (tungsten target source), the reduction of Eu3+ towards Eu2+ was observed. This reduction behaviour was thoroughly recorded, and the linearity of the process was determined. Furthermore, the relationship between the acceleration voltage and the reduction process is discussed.

Single-crystal sapphire microstructure for high-resolution synchrotron X-ray monochromators

DOE PAGES

Asadchikov, Victor E.; Butashin, Andrey V.; Buzmakov, Alexey V.; ...

2016-03-22

We report on the growth and characterization of several sapphire single crystals for the purpose of x-ray optics applications. Structural defects were studied by means of laboratory double-crystal X-ray diffractometry and white beam synchrotron-radiation topography. The investigations confirmed that the main defect types are dislocations. The best quality crystal was grown using the Kyropoulos technique with a dislocation density of 10 2-10 3 cm -2 and a small area with approximately 2*2 mm 2 did not show dislocation contrast in many reflections and has suitable quality for application as a backscattering monochromator. As a result, a clear correlation between growthmore » rate and dislocation density is observed, though growth rate is not the only parameter impacting the quality.« less

Preparation and characterization of silk sericin/PVA blend film with silver nanoparticles for potential antimicrobial application.

PubMed

He, Huawei; Cai, Rui; Wang, Yejing; Tao, Gang; Guo, Pengchao; Zuo, Hua; Chen, Liqun; Liu, Xinyu; Zhao, Ping; Xia, Qingyou

2017-11-01

Sericin has great potentials in biomedical applications for its good reactive activity, biocompatibility and biodegradability. However, the undesirable mechanical performance limits its application. Here, we developed a green, facile and economic approach to prepare sericin/polyvinyl alcohol (PVA) blend film. Further, silver nanoparticles (AgNPs) were synthesized in situ on the surface of sericin/PVA film via UV-assisted green synthesis method. Mechanical performance, swelling, mass losing and water retention tests showed the blend film had good mechanical performance, hygroscopicity, water retention capacity and low mass losing ratio. Scanning electron microscopy, fourier transfer infrared spectroscopy, X-ray diffractometry diffraction and X-ray photoelectron spectroscopy indicated the blending of PVA and sericin promoted the formation of hydrogen bond network between sericin and PVA, thus enhanced the mechanical performance and the stability of sericin, as well as the hygroscopicity and water retention capacity. UV irradiation and AgNPs modification did not affect the inner crystalline structure of sericin/PVA blend film. The inhibition zone and bacteria growth curve assay suggested AgNPs-sericin/PVA film had good antibacterial activities against E. coli and S. aureus. This novel AgNPs-sericin/PVA film shows great potentials in biomedical materials such as wound dressing and skin tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of microsphere silicon carbide/nanoneedle manganese oxide composites and their electrochemical properties as supercapacitors

NASA Astrophysics Data System (ADS)

Kim, Myeongjin; Yoo, Youngjae; Kim, Jooheon

2014-11-01

Synthesis of microsphere silicon carbide/nanoneedle MnO2 (SiC/N-MnO2) composites for use as high-performance materials in supercapacitors is reported herein. The synthesis procedure involves the initial treatment of silicon carbide (SiC) with hydrogen peroxide to obtain oxygen-containing functional groups to provide anchoring sites for connection of SiC and the MnO2 nanoneedles (N-MnO2). MnO2 nanoneedles are subsequently formed on the SiC surface. The morphology and microstructure of the as-prepared composites are characterized via X-ray diffractometry, field-emission scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The characterizations indicate that MnO2 nanoneedles are homogeneously formed on the SiC surface in the composite. The capacitive properties of the as-prepared SiC/N-MnO2 electrodes are evaluated using cyclic voltammetry, galvanostatic charge/discharge testing, and electrochemical impedance spectroscopy in a three-electrode experimental setup using a 1-M Na2SO4 aqueous solution as the electrolyte. The SiC/N-MnO2(5) electrode, for which the MnO2/SiC feed ratio is 5:1, displays a specific capacitance as high as 273.2 F g-1 at 10 mV s-1.

Synthesis of Ti-6Al-4V alloy with nano-TiN microstructure via spark plasma sintering technique

NASA Astrophysics Data System (ADS)

E Falodun, O.; Obadele, B. A.; Oke, S. R.; E Maja, M.; Olubambi, P. A.

2017-12-01

The effect of nano-TiN dispersion strengthened Ti-6Al-4V via spark plasma sintering method has been investigated. Ti-6Al-4V with 4 vol. percent of nano-TiN were mixed in a Turbula shaker mixer for 8 h at a speed of 49 rpm and the admixed powders were sintered at sintering temperature range of 1000 - 1100 °C, holding time of 10-30 mins, heating rate of 100 °C/min under an applied pressure of 50 MPa. The morphology of the as-received and sintered compacts was examined by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and phase analysis was done by X-ray diffractometry (XRD). The sintered compacts without nano-TiN reveal lamellar structure while reinforced Ti-6Al-4V with nano-TiN shows a bimodal structure and titanium nitride has a great influence on a grain growth at high temperature. Furthermore, the microstructural formation mechanism was investigated. With the addition of the content of Ti-6Al-4V with 4 vol.% of nano-TiN, the micro-hardness also improved and this was due to homogenous distribution of TiN in Ti-6Al-4V matrix.

New thin films of NiO doped with V2O5 for electrochromic applications

NASA Astrophysics Data System (ADS)

Azevedo, Cristiane F.; Balboni, Raphael D. C.; Cholant, Camila M.; Moura, Elton A.; Lemos, Rafaela M. J.; Pawlicka, Agnieszka; Gündel, Andre; Flores, Wladimir H.; Pereira, Marcelo; Avellaneda, César O.

2017-11-01

This paper reports on synthesis and characterization of new electrochromic thin films of NiO doped with V2O5 that were prepared by the sol-gel method and deposited by the spin coating technique. The confirmation of the presence of the dopant in the structure of the films was given by energy-dispersive X-ray spectroscopy (EDX). The effect of the addition of vanadium to the films of NiO was evaluated by electrochemical techniques such as cyclic voltammetry, chronocoulometry, and chronoamperometry in 0.5 mol/L KOH electrolyte. The morphology and the structure of the films, determined by microscopies (SEM and AFM), reveal smooth and slightly rough surfaces. The addition of vanadium as a dopant does not produce changes in the host NiO matrix as evidenced by X-ray diffractometry (XRD). However, the addition of the dopant causes a significant improvement in a charge density values of the films that increase more than twice from 25.5 mC/cm2 for NiO to 52.8 mC/cm2 for NiO with 10 mol% of V2O5. V2O5 doping of NiO films also improved their optical properties as well as kinetics of insertion and extraction processes.

Influence of Sintering Temperature on Mechanical and Physical properties of Mill Scale based Bipolar Plates for PEMFC

NASA Astrophysics Data System (ADS)

Khaerudini, Deni S.; Berliana, Rina; Prakoso, Gatra B.; Insiyanda, Dita R.; Alva, Sagir

2018-03-01

This work concerns the utilization of mill scale, a by-product of iron and steel formed during the hot rolling of steel, as a potential material for use as bipolar plates in proton exchange membrane fuel cells (PEMFCs). On the other hand, mill scale is considered a very rich in iron source having characteristic required such as for current collector in bipolar plate and would significantly contribute to lower the overall cost of PEMFC based fuel cell systems. In this study, the iron reach source of mill scale powder, after sieving of 150 mesh, was mechanically alloyed with the aluminium source containing 30 wt.% using a shaker mill for 3 h. The mixed powders were then pressed at 300 MPa and sintered at various temperatures of 400, 450 and 500 °C for 1 h under inert gas atmosphere. The structural changes of powder particles during mechanical alloying and after sintering were studied by x-ray diffractometry, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), microhardness measurement, and density - porosity analysis. The details of the performance variation of three different sintering conditions can be preliminary explained by the metallographic and crystallographic structure and phase analysis as well as sufficient mechanical strength of the sintered materials was presented in this report.

Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

PubMed Central

Kim, Hae Ri; Jang, Seong-Ho; Kim, Young Kyung; Son, Jun Sik; Min, Bong Ki; Kim, Kyo-Han; Kwon, Tae-Yub

2016-01-01

The microstructures and mechanical properties of cobalt-chromium (Co-Cr) alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique. Four groups of disc- (microstructures) or dumbbell- (mechanical properties) specimens made of Co-Cr alloys were prepared using casting (CS), milling (ML), selective laser melting (SLM), and milling/post-sintering (ML/PS). For each technique, the corresponding commercial alloy material was used. The microstructures of the specimens were evaluated via X-ray diffractometry, optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy, and electron backscattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test according to ISO 22674 (n = 6). The microstructure of the alloys was strongly influenced by the manufacturing processes. Overall, the SLM group showed superior mechanical properties, the ML/PS group being nearly comparable. The mechanical properties of the ML group were inferior to those of the CS group. The microstructures and mechanical properties of Co-Cr alloys were greatly dependent on the manufacturing technique as well as the chemical composition. The SLM and ML/PS techniques may be considered promising alternatives to the Co-Cr alloy casting process. PMID:28773718

Formation of Al3Ti/Mg composite by powder metallurgy of Mg-Al-Ti system.

PubMed

Yang, Zi R; Qi Wang, Shu; Cui, Xiang H; Zhao, Yu T; Gao, Ming J; Wei, Min X

2008-07-01

An in situ titanium trialuminide (Al 3 Ti)-particle-reinforced magnesium matrix composite has been successfully fabricated by the powder metallurgy of a Mg-Al-Ti system. The reaction processes and formation mechanism for synthesizing the composite were studied by differential scanning calorimetry (DSC), x-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Al 3 Ti particles are found to be synthesized in situ in the Mg alloy matrix. During the reaction sintering of the Mg-Al-Ti system, Al 3 Ti particles are formed through the reaction of liquid Al with as-dissolved Ti around the Ti particles. The formed intermetallic particles accumulate at the original sites of the Ti particles. As sintering time increases, the accumulated intermetallic particles disperse and reach a relatively homogeneous distribution in the matrix. It is found that the reaction process of the Mg-Al-Ti system is almost the same as that of the Al-Ti system. Mg also acts as a catalytic agent and a diluent in the reactions and shifts the reactions of Al and Ti to lower temperatures. An additional amount of Al is required for eliminating residual Ti and solid-solution strengthening of the Mg matrix.

Iron-antimony-based hybrid oxides as high-performance anodes for lithium-ion storage

NASA Astrophysics Data System (ADS)

Nguyen, Tuan Loi; Kim, Doo Soo; Hur, Jaehyun; Park, Min Sang; Yoon, Sukeun; Kim, Il Tae

2018-06-01

We report a facile approach to synthesize Fe-Sb-based hybrid oxides nanocomposites consisting of Sb, Sb2O3, and Fe3O4 for use as new anode materials for lithium-ion batteries. The composites are synthesized via galvanic replacement between Fe3+ and Sb at high temperature in triethylene glycol medium. The phase, morphology, and composition changes of the composites involved in the various stages of the replacement reaction are characterized using X-ray diffractometry, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The as-prepared composites have different compositions with very small particle sizes (<< 10 nm). The FexSbyOz-18 h composite, for instance, exhibits high capacity, better cyclic stability, and rate performance than other composites, with a highly stable specific capacity of 434 mAh g-1 at 500 cycles. The excellent electrochemical performance can be ascribed to the high interfacial contact area between the nanocomposite and electrolyte, stable structure of the composites owing to a mixture of inactive phases generated by the conversion reaction between Li+ and oxide metal-whose structure serves as an electron conductor, inhibits agglomeration of Sb particles, and acts as an effective buffer against volume change of Sb during cycling-and high Li+ diffusion ability.

Ultrasonic spray pyrolysis synthesis of reduced graphene oxide/anatase TiO2 composite and its application in the photocatalytic degradation of methylene blue in water.

PubMed

Park, Jeong-Ann; Yang, Boram; Lee, Joongki; Kim, In Gyeom; Kim, Jae-Hyun; Choi, Jae-Woo; Park, Hee-Deung; Nah, In Wook; Lee, Sang-Hyup

2018-01-01

Reduced graphene oxide (RGO)/anatase TiO 2 composite was prepared using a simple one-step technique-ultrasonic spray pyrolysis-in order to inhibit the aggregation of TiO 2 nanoparticles and to improve the photocatalytic performance for degradation of methylene blue (MB). Different proportions (0-5 wt%) of RGO/TiO 2 composites were characterized by scanning electronic microscopy (SEM), dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), Raman spectroscopy, UV-vis spectroscopy, and electrochemical impedance spectroscopy (EIS) to verify mechanism. From these analysis, TiO 2 nanoparticles are distributed uniformly on the RGO sheets with crumpled shape during ultrasonic spray pyrolysis and surface area is increasing by increasing portion of RGO. Band gap of RGO 5 /TiO 2 (5 wt% of RGO) composite is 2.72 eV and band gap was reduced by increasing portion of RGO in RGO/TiO 2 composites. The RGO 5 /TiO 2 composite was superior to other lower content of RGO/TiO 2 composites with a rapid transport of charge carriers and an effective charge separation. The highest removal efficiency of MB was obtained at the RGO 5 /TiO 2 composite under UVC irradiation, which coincided with the EIS, and the optimal dose of the composite was determined to be 0.5 g/L. The RGO 5 /TiO 2 composite improve the photocatalytic degradation rate of MB over the TiO 2 due to a retardation of electron-hole recombination. The MB adsorption capacity and photocatalytic degradation efficiency were greatly affected by pH changes and increased with increasing pH due to electrostatic interactions and generation of more hydroxyl radicals. The reusability of RGO 5 /TiO 2 composite was examined during 3 cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced Photocatalytic Activity toward Organic Pollutants Degradation and Mechanism Insight of Novel CQDs/Bi₂O₂CO₃ Composite.

PubMed

Zhang, Zisheng; Lin, Shuanglong; Li, Xingang; Li, Hong; Zhang, Tong; Cui, Wenquan

2018-05-15

Novel carbon quantum dots (CQDs) modified with Bi₂O₂CO₃ (CQDs/Bi₂O₂CO₃) were prepared using a simple dynamic-adsorption precipitation method. X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) were used to test the material composition, structure, and band structures of the as-prepared samples. Methylene blue (MB) and colorless phenol, as target organic pollutants, were used to evaluate the photocatalytic performance of the CQDs/Bi₂O₂CO₃ hybrid materials under visible light irradiation. Experimental investigation shows that 2⁻5 nm CQDs were uniformly decorated on the surface of Bi₂O₂CO₃; CQDs/Bi₂O₂CO₃ possess an efficient photocatalytic performance, and the organic matter removal rate of methylene blue and phenol can reach up to 94.45% and 61.46% respectively, within 2 h. In addition, the degradation analysis of phenol by high performance liquid chromatography (HPLC) proved that there are no other impurities in the degradation process. Photoelectrochemical testing proved that the introduction of CQDs (electron acceptor) effectively suppresses the recombination of e - -h⁺, and promotes charge transfer. Quenching experiments and electron spin resonance (ESR) suggested that ·OH, h⁺, and ·O₂ - were involved in the photocatalytic degradation process. These results suggested that the up-conversion function of CQDs could improve the electron transfer and light absorption ability of photocatalysts and ·O₂ - formation. Furthermore, the up-conversion function of CQDs would help maintain photocatalytic stability. Finally, the photocatalytic degradation mechanism was proposed according to the above experimental result.

Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

2016-03-01

To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

Mineralogical variation in the size fractions of a Ranong kaolin, southern Thailand

NASA Astrophysics Data System (ADS)

Pisutha-Arnond, Visut; Phuvichit, Suraphol; Leepowpanth, Quanchai

A representative crude Ranong kaolin from the Thungkla-Ranong mine was separated into > 2 mm (granule), 2-1 mm (very coarse sand), 1-0.5 mm (coarse sand), 0.5-0.25 mm (medium sand), 0.25-0.125 mm (fine sand), 0.125-0.062 mm (very fine sand) and 62-28, 28-14, 17-7, 7-4, 4-2, 2-1 and < 1 μ m size fractions. Those size fractions were analyzed by X-ray powder diffractometry (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with attached energy dispersive X-ray spectrometer (EDX). Kaolin group minerals were differentiated by using XRD in combination with various chemical and heat treatments together with TEM, SEM and DTA. The Ranong kaolin consists predominantly of tubular halloysite, poorly crystallized kaolinite and quartz with minor amounts of mica and K-feldspars. Other trace constituents include gibbsite, tourmaline, zircon and colored impurities (i.e. extractable iron hydroxide coating on clay mineral surface). The kaolin minerals are found in all size fractions by which their contents and halloysite/kaolinite ratios increase as the particle sizes become finer. Quartz and mica are also detected in almost all size fractions. They are, however, more abundant with coarsening particle size. Gibbsite, K-feldspar and tourmaline are mainly concentrated in the fine sand to silt size fractions. Crystallinity of kaolin minerals as measured by XRD varied moderately with size. Relatively pure kaolin minerals, predominantly halloysite and kaolinite, can be obtained in the particle size below 1 or 2 μm.

Microstructure and properties of Fe-based composite coating by laser cladding Fe-Ti-V-Cr-C-CeO2 powder

NASA Astrophysics Data System (ADS)

Zhang, Hui; Zou, Yong; Zou, Zengda; Wu, Dongting

2015-01-01

In situ TiC-VC reinforced Fe-based cladding layer was obtained on low carbon steel surface by laser cladding with Fe-Ti-V-Cr-C-CeO2 alloy powder. The microstructure, phases and properties of the cladding layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe-Ti-V-Cr-C-CeO2 alloy powder formed a good cladding layer without defects such as cracks and pores. The phases of the cladding layer were α-Fe, γ-Fe, TiC, VC and TiVC2. The microstructures of the cladding layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5-2 μm and distributed uniformly in the cladding layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC2. The cladding layer with a hardness of 1030 HV0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.

Heats of immersion of titania powders in primer solutions

NASA Technical Reports Server (NTRS)

Siriwardane, R.; Wightman, J. P.

1983-01-01

The oxide layer present on titanium alloys can play an important role in determining the strength and durability of adhesive bonds. Here, three titania powders in different crystalline phases, rutile-R1, anatase-A1, and anatase-A2, are characterized by several techniques. These include microelectrophoresis, X-ray diffractometry, surface area pore volume analysis, X-ray photoelectron spectroscopy, and measurements of the heats of immersion. Of the three powders, R1 has the highest heat of immersion in water, while the interaction between water and A1 powder is low. Experimental data also suggest a specific preferential interaction of polyphenylquinoxaline with anatase.

Structural properties of ultrafine Ba-hexaferrite nanoparticles

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

Makovec, Darko, E-mail: Darko.Makovec@ijs.si; Primc, Darinka; Sturm, Saso

2012-12-15

Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Moessbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH{sup -}. The ultrafine nanoparticles were formed in a discoid shape, {approx}10 nm wide and only {approx}3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction.more » The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe{sub 12}O{sub 19} formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization. - Graphical abstract: Left: HREM image of an ultrafine Ba-hexaferrite nanoparticle (inset: TEM image of the nanoparticles); Right: the experimental HRTEM image is compared with calculated image and corresponding atomic model. Highlights: Black-Right-Pointing-Pointer Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was compared to the structure of the bulk. Black-Right-Pointing-Pointer Thickness the discoid nanoparticles was comparable to the size of the hexagonal unit cell in the c-direction. Black-Right-Pointing-Pointer Considerable disorder of the nanoparticles' structure is most probably responsible for their low magnetization.« less

Chemical compositions, infrared spectroscopy, and X-ray diffractometry study on brown-rotted woods

Treesearch

Gai-Yun Li; Luo-Hua Huang; Chung Hse; Te-Fu Qin

2011-01-01

The effect of brown-rot decay on the chemical composition and crystallinity of Masson pine was studied by exposing it to Wolfiporia cocos (Schwein.) Ryvarden and Gilbn. for durations of up to 15 weeks in the field. The holocellulose content, α-cellulose content, and wood crystallinity decreased slowly in the initial stage, followed by a significant reduction...

Synthesis of high generation thermo-sensitive dendrimers for extraction of rivaroxaban from human fluid and pharmaceutic samples.

PubMed

Parham, Negin; Panahi, Homayon Ahmad; Feizbakhsh, Alireza; Moniri, Elham

2018-04-13

In this present study, poly (N-isopropylacrylamide) as a thermo-sensitive agent was grafted onto magnetic nanoparticles, then ethylenediamine and methylmethacrylate were used to synthesize the first generation of poly amidoamine (PAMAM) dendrimers successively and the process continued alternatively until the ten generations of dendrimers. The synthesized nanocomposite was investigated using Fourier transform infrared spectrometry, thermalgravimetry analysis, X-ray diffractometry, elemental analysis and vibrating-sample magnetometer. The particle size and morphology were characterized using dynamic light scattering, field emission scanning electron microscopy and transmission electron microscopy. Batch experiments were conducted to investigate the parameters affecting adsorption and desorption of rivaroxaban by synthesized nanocomposite. The maximum sorption of rivaroxaban by the synthesized nanocomposite was obtained at pH of 8. The resulting grafted magnetic nanoparticle dendrimers were applied for extraction of rivaroxaban from biologic human liquids and medicinal samples. The specifications of rivaroxaban sorbed by a magnetic nanoparticle dendrimer showed good accessibility and high capacity of the active sites within the dendrimers. Urine and drug matrix extraction recoveries of more than 92.5 and 99.8 were obtained, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Growth of ferroelectric Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} epitaxial films by ultraviolet pulsed laser irradiation of chemical solution derived precursor layers

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

Queraltó, A.; Pérez del Pino, A., E-mail: aperez@icmab.es; Mata, M. de la

2015-06-29

Highly crystalline epitaxial Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} (BST) thin-films are grown on (001)-oriented LaNiO{sub 3}-buffered LaAlO{sub 3} substrates by pulsed laser irradiation of solution derived barium-zirconium-titanium precursor layers using a UV Nd:YAG laser source at atmospheric conditions. The structural analyses of the obtained films, studied by X-ray diffractometry and transmission electron microscopy, demonstrate that laser processing allows the growth of tens of nm-thick BST epitaxial films with crystalline structure similar to that of films obtained through conventional thermal annealing methods. However, the fast pulsed nature of the laser employed leads to crystallization kinetic evolution orders of magnitude faster than inmore » thermal treatments. The combination of specific photothermal and photochemical mechanisms is the main responsible for the ultrafast epitaxial laser-induced crystallization. Piezoresponse microscopy measurements demonstrate equivalent ferroelectric behavior in laser and thermally annealed films, being the piezoelectric constant ∼25 pm V{sup −1}.« less

Effect of heavy tempering on microstructure and yield strength of 28CrMo48VTiB martensitic steel

NASA Astrophysics Data System (ADS)

Sun, Yu; Gu, Shunjie; Wang, Qian; Wang, Huibin; Wang, Qingfeng; Zhang, Fucheng

2018-02-01

The 28CrMo48VTiB martensitic steel for sulfide stress cracking (SSC) resistance oil country tubular goods (OCTG) of C110 grade was thermally processed through quenching at 890 °C and tempering at 600 °C-720 °C for 30-90 min. The microstructures of all samples were characterized using field emission scanning electron microscopy (FESEM), electron backscattering diffraction (EBSD), transmission electron microscopy (TEM) and x-ray diffractometry (XRD). Also, the tensile properties were measured. The results indicated that the yield strength (YS) decreased as both the tempering temperature and duration increased, due to the coarsening of martensitic packet/block/lath structures, the reduction of dislocation density, as well as the increase of both the volume fraction and average diameter of the precipitates. The martensitic lath width was the key microstructural parameter controlling the YS of this heavily-tempered martensitic steel, whereas the corresponding relationship was in accordance with the Langford-Cohen model. Furthermore, the martensitic structure boundary and the solid solution strengthening were the two most significant factors dominating the YS, in comparison with the dislocation and precipitation strengthening.

Effect of Ca addition on the damping capacity of Mg-Al-Zn casting alloys

NASA Astrophysics Data System (ADS)

Jun, Joong-Hwan; Moon, Jung-Hyun

2015-07-01

The influences of Ca addition on the microstructures and damping capacities of AZ91-(0˜2)%Ca casting alloys were investigated, on the basis of the results of X-ray diffractometry, optical microscopy, scanning electron microscopy and vibration tests in a single cantilever mode. The amount of intermetallic compounds decreased with increasing Ca content up to 0.5%, above which it increased; the average cell size showed the opposite tendency. All alloys exhibited similar damping levels in the strain-amplitude independent region. Considering the very low solubility of Ca in the matrix, and that most of the Ca elements are consumed by the formation of the Al2Ca phase and incorporation into the Mg17Al12 phase, this would be ascribed to the almost identical concentrations of Ca solutes distributed in the matrix. In the strain-amplitude dependent region, however, the AZ91-0.5%Ca alloy possessed the maximum damping capacity. From the viewpoint of microstructural evolution with Ca addition, the number density of compound particles is considered to be the principal factor affecting the damping behavior in the strain-amplitude dependent region.

Observation of defect-induced Photoresponse and charge carrier transport in single GeSe2 nanobelt devices

NASA Astrophysics Data System (ADS)

Mukherjee, Bablu; Tok, Eng Soon; Haur Sow, Chorng

2013-03-01

Single crystal GeSe2 nanobelts were grown using chemical vapor deposition techniques. Morphology of the nanostructures was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectroscopy. Electronic transport properties, impedance spectroscopy, photoconductive characteristics and temperature-dependent electrical resistivity measurements were carried out on individual GeSe2 nanobelt devices. The photosensitivity of single GeSe2 nanobelt (NB) devices was examined with two different excitation wavelengths of laser beams with photon energies above band gap and at sub-band gap of the NB. A maximum photoconductive gain 106 % was achieved at a wavelength of 808 nm. The magnitude of the photocurrent and response time of the individual GeSe2 NB device indicate that the photoresponse could be attributed to the presence of isolated mid band gap defect levels. Temperature dependent photocurrent measurements indicate the rough estimation of the energy levels for the defect states. Localized photostudy shows that the large photoresponse of the device primarily occurs at the metal-NB contact regions. Department of Physics, 2 Science Drive 3, National University of Singapore (NUS), Singapore 117542

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB2 powders

NASA Astrophysics Data System (ADS)

Diao, Yunhua; Zhang, Kemin

2015-10-01

In the present work, a TiC/TiB2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB2 powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB2. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB2 intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens' corrosion property is clearly becoming better than that of the substrate.

Chitosan microparticles: influence of the gelation process on the release profile and oral bioavailability of albendazole, a class II compound.

PubMed

Piccirilli, Gisela N; García, Agustina; Leonardi, Darío; Mamprin, María E; Bolmaro, Raúl E; Salomón, Claudio J; Lamas, María C

2014-11-01

Encapsulation of albendazole, a class II compound, into polymeric microparticles based on chitosan-sodium lauryl sulfate was investigated as a strategy to improve drug dissolution and oral bioavailability. The microparticles were prepared by spray drying technique and further characterized by means of X-ray powder diffractometry, infrared spectroscopy and scanning electron microscopy. The formation of a novel polymeric structure between chitosan and sodium lauryl sulfate, after the internal or external gelation process, was observed by infrared spectroscopy. The efficiency of encapsulation was found to be between 60 and 85% depending on the internal or external gelation process. Almost spherically spray dried microparticles were observed using scanning electron microscopy. In vitro dissolution results indicated that the microparticles prepared by internal gelation released 8% of the drug within 30 min, while the microparticles prepared by external gelation released 67% within 30 min. It was observed that the AUC and Cmax values of ABZ from microparticles were greatly improved, in comparison with the non-encapsulated drug. In conclusion, the release properties and oral bioavailability of albendazole were greatly improved by using spraydried chitosan-sodium lauryl sulphate microparticles.

X-Ray Microanalytic Concentration Measurements in Unsectioned Specimens: a Technique and its Application to Zinc, Manganese, and Iron Enriched Mechanical Structures of Organisms from Three Phyla

NASA Astrophysics Data System (ADS)

Schofield, Robert M. S.

A method for measuring concentrations of minor elements in microscopic volumes of heterogeneous, unsectioned biological specimens using an ion microprobe is developed. The element quantity is obtained from PIXE (Proton Induced X-ray Emission) and the total quantity of material is derived from STIM (Scanning Transmission Ion Microscopy) energy loss measurements. Sources of error, including changes in x-ray production cross section with proton energy and absorption of induced x-rays, are discussed and a method of calculating the total measurement uncertainty, typically about 25% here, is developed. The measurement accuracy is shown to be improved for symmetric specimens, and a method of using the bremsstrahlung background to correct for x-ray attenuation within irregular specimens is developed. Methods for measuring local concentrations in internal features are also discussed. With this technique, scorpions were found to contain cuticular accumulations of one or more heavy metals (manganese up to 5% of dry weight, iron up to 8%, zinc up to 24%) in the chelicera, pedipalp denticles, tarsal claws, and stingers; different region soften contained different metals. The stingers are argued to be of particular interest because they are not homologous to legs. Similar accumulations were found in spiders, some other chelicerates and crustaceans. Previous reports of manganese and zinc accumulations in insect and worm mouth parts were augmented with local concentration measurements and with the detection of other enrichment features (such as 6% iron in the paragnaths of the worm Nereis vexillosa). Zinc accumulations (up to only 0.1%) were also found in the tips of the teeth of a hagfish, Myxine + glutinosa. X-ray images of several of these features are presented. It is argued that the extreme magnitude of some concentration values suggests that some metals are incorporated in unusual biominerals rather than organically bound. Results of x-ray diffractometry and Vickers microhardness measurements are reported although the results are inconclusive. The atomic ratio of zinc to chlorine in these accumulations is shown not to be constant. It is suggested from their typical locations that at least two of the observed accumulation patterns impart different mechanical properties to the cuticle.

Correlation Between the Extent of Catalytic Activity and Charge Density of Montmorillonites

PubMed Central

Steudel, Annett; Emmerich, Katja; Lagaly, Gerhard; Schuhmann, Rainer

2010-01-01

Abstract The clay mineral montmorillonite is a member of the phyllosilicate group of minerals, which has been detected on martian soil. Montmorillonite catalyzes the condensation of activated monomers to form RNA-like oligomers. Extent of catalysis, that is, the yield of oligomers, and the length of the longest oligomer formed in these reactions widely varies with the source of montmorillonite (i.e., the locality where the mineral is mined). This study was undertaken to establish whether there exists a correlation between the extent of catalytic property and the charge density of montmorillonites. Charge density was determined by saturating the montmorillonites with alkyl ammonium cations that contained increasing lengths of alkyl chains, [CH3-(CH2)n-NH3]+, where n = 3–16 and 18, and then measuring d(001), interlayer spacing of the resulting montmorillonite-alkyl ammonium-montmorillonite complex by X-ray diffractometry (XRD). Results demonstrate that catalytic activity of montmorillonites with lower charge density is superior to that of higher charge density montmorillonite. They produce longer oligomers that contain 9 to 10 monomer units, while montmorillonite with high charge density catalyzes the formation of oligomers that contain only 4 monomer units. The charge density of montmorillonites can also be calculated from the chemical composition if elemental analysis data of the pure mineral are available. In the next mission to Mars, CheMin (Chemistry and Mineralogy), a combined X-ray diffraction/X-ray fluorescence instrument, will provide information on the mineralogical and elemental analysis of the samples. Possible significance of these results for planning the future missions to Mars for the search of organic compounds and extinct or extant life is discussed. Key Words: Mars—Origin of life—Montmorillonite—Mineral catalysis—Layer charge density—X–ray diffractometry. Astrobiology 10, 743–749. PMID:20854214

Modified extrusion-spheronization as a technique of microencapsulation for stabilization of choline bitartrate using hydrogenated soya bean oil.

PubMed

Gangurde, Avinash Bhaskar; Sav, Ajay Kumar; Javeer, Sharadchandra Dagadu; Moravkar, Kailas K; Pawar, Jaywant N; Amin, Purnima D

2015-01-01

Choline bitartrate (CBT) is a vital nutrient for fetal brain development and memory function. It is hygroscopic in nature which is associated with stability related problem during storage such as development of fishy odor and discoloration. Microencapsulation method was adopted to resolve the stability problem and for this hydrogenated soya bean oil (HSO) was used as encapsulating agent. Industrially feasible modified extrusion-spheronization technique was selected for microencapsulation. HSO was used as encapsulating agent, hydroxypropyl methyl cellulose E5/E15 as binder and microcrystalline cellulose as spheronization aid. Formulated pellets were evaluated for parameters such as flow property, morphological characteristics, hardness-friability index (HFI), drug content, encapsulation efficiency, and in vitro drug release. The optimized formulations were also characterized for particle size (by laser diffractometry), differential scanning calorimetry, powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy, and scanning electron microscopy. The results from the study showed that coating of 90% and 60% CBT was successful with respect to all desired evaluation parameters. Optimized formulation was kept for 6 months stability study as per ICH guidelines, and there was no change in color, moisture content, drug content, and no fishy odor was observed. Microencapsulated pellets of CBT using HSO as encapsulating agent were developed using modified extrusion spheronization technique. Optimized formulations, CBT 90% (F5), and CBT 60% (F10), were found to be stable for 4M and 6M, respectively, at accelerated conditions.

LiFePO4 Nanostructures Fabricated from Iron(III) Phosphate (FePO4 x 2H2O) by Hydrothermal Method.

PubMed

Saji, Viswanathan S; Song, Hyun-Kon

2015-01-01

Electrode materials having nanometer scale dimensions are expected to have property enhancements due to enhanced surface area and mass/charge transport kinetics. This is particularly relevant to intrinsically low electronically conductive materials such as lithium iron phosphate (LiFePO4), which is of recent research interest as a high performance intercalation electrode material for Li-ion batteries. Many of the reported works on LiFePO4 synthesis are unattractive either due to the high cost of raw materials or due to the complex synthesis technique. In this direction, synthesis of LiFePO4 directly from inexpensive FePO4 shows promise.The present study reports LiFePO4 nanostructures prepared from iron (III) phosphate (FePO4 x 2H2O) by precipitation-hydrothermal method. The sintered powder was characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Inductive coupled plasma-optical emission spectroscopy (ICP-OES), and Electron microscopy (SEM and TEM). Two synthesis methods, viz. bulk synthesis and anodized aluminum oxide (AAO) template-assisted synthesis are reported. By bulk synthesis, micro-sized particles having peculiar surface nanostructuring were formed at precipitation pH of 6.0 to 7.5 whereas typical nanosized LiFePO4 resulted at pH ≥ 8.0. An in-situ precipitation strategy inside the pores of AAO utilizing the spin coating was utilized for the AAO-template-assisted synthesis. The template with pores filled with the precipitate was subsequently subjected to hydrothermal process and high temperature sintering to fabricate compact rod-like structures.

The Synergistic Effect of Iodide and Sodium Nitrite on the Corrosion Inhibition of Mild Steel in Bicarbonate-Chloride Solution.

PubMed

Eyu, Gaius Debi; Will, Geoffrey; Dekkers, Willem; MacLeod, Jennifer

2016-10-26

The effect of potassium iodide (KI) and sodium nitrite (NaNO₂ inhibitor on the corrosion inhibition of mild steel in chloride bicarbonate solution has been studied using electrochemical techniques. Potentiodynamic polarisation data suggest that, when used in combination, KI and NaNO₂ function together to inhibit reactions at both the anode and the cathode, but predominantly anodic. KI/NO₂ - concentration ratios varied from 2:1 to 2:5; inhibition efficiency was optimized for a ratio of 1:1. The surface morphology and corrosion products were analysed using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The latter shows that the addition of I - to NO₂ facilitates the formation of a passivating oxide (γ-Fe₂O₃) as compared to NO₂ - alone, decreasing the rate of metal dissolution observed in electrochemical testing. The synergistic effect of KI/NO₂ - inhibition was enhanced under the dynamic conditions associated with testing in a rotating disc electrode.

Mortar radiocarbon dating: preliminary accuracy evaluation of a novel methodology.

PubMed

Marzaioli, Fabio; Lubritto, Carmine; Nonni, Sara; Passariello, Isabella; Capano, Manuela; Terrasi, Filippo

2011-03-15

Mortars represent a class of building and art materials that are widespread at archeological sites from the Neolithic period on. After about 50 years of experimentation, the possibility to evaluate their absolute chronology by means of radiocarbon ((14)C) remains still uncertain. With the use of a simplified mortar production process in the laboratory environment, this study shows the overall feasibility of a novel physical pretreatment for the isolation of the atmospheric (14)CO(2) (i.e., binder) signal absorbed by the mortars during their setting. This methodology is based on the assumption that an ultrasonic attack in liquid phase isolates a suspension of binder carbonates from bulk mortars. Isotopic ((13)C and (14)C), % C, X-ray diffractometry (XRD), and scanning electron microscopy (SEM) analyses were performed to characterize the proposed methodology. The applied protocol allows suppression of the fossil carbon (C) contamination originating from the incomplete burning of the limestone during the quick lime production, providing unbiased dating for "laboratory" mortars produced operating at historically adopted burning temperatures.

Phase purity of NiCo2O4, a catalyst candidate for electrolysis of water

NASA Technical Reports Server (NTRS)

Singer, J.; Fielder, W. L.; Garlick, R. G.; Negas, T.

1987-01-01

NiCo2O4 is shown to be difficult to obtain as a pure phase, and may never have been so obtained. High resolution x-ray diffractometry is required for its precise characterization. Film XRD is not likely to show the asymmetry in the spinel diffraction lines, caused by poorly crystallized NiO, as seen in diffractometer traces. The Co3O4 which is expected to accompany NiO as an impurity in NiCo2O4 syntheses has the same diffraction pattern as the binary oxide. Firings of the co-precipitated hydroxides at 300, 350, and 400 C, including one in pure O2, failed to produce single phase cobaltate. Scanning electron microscopy showed all the sintered products to range over several orders of magnitude in agglomerate/particle size. Surface areas by BET were all in the range 40 to 110 m sq/g, equivalent to particles of 200 to 100 Angstrom diameter. The spinel diffraction line breadths were compatible with those approximate dimensions.

Hydrothermal synthesis of nanostructured Y2O3 and (Y0.75Gd0.25)2O3 based phosphors

NASA Astrophysics Data System (ADS)

Mančić, Lidija; Lojpur, Vesna; Marinković, Bojan A.; Dramićanin, Miroslav D.; Milošević, Olivera

2013-08-01

Examples of (Y2O3-Gd2O3):Eu3+ and Y2O3:(Yb3+/Er3+) rare earth oxide-based phosphors are presented to highlight the controlled synthesis of 1D and 2D nanostructures through simple hydrothermal method. Conversion of the starting nitrates mixture into carbonate hydrate phase is performed with the help of ammonium hydrogen carbonate solution during hydrothermal treatment at 200 °C/3 h. Morphological architectures of rare earth oxides obtained after subsequent powders thermal treatment at 600 and 1100 °C for 3 and 12 h and their correlation with the optical characteristics are discussed based on X-ray powder diffractometry, field emission scanning electron microscopy, infrared spectroscopy and photoluminescence measurements. Strong red and green emission followed by the superior decay times are attributed to the high powders purity and homogeneous dopants distribution over the host lattice matrix.

Effect of Laser Powder Bed Fusion Parameters on the Microstructure and Texture Development in Superelastic Ti-18Zr-14Nb Alloy

NASA Astrophysics Data System (ADS)

Kreitcberg, A.; Brailovski, V.; Sheremetyev, V.; Prokoshkin, S.

2017-12-01

The effect of different laser powder bed fusion (L-PBF) parameters on the phase composition, microstructure, and crystallographic texture of Ti-18Zr-14Nb alloy was studied. Two levels of laser power, scanning speed, and hatching space were used, while the layer thickness was kept constant. The resulting volume energy density was ranged from 20 to 60 J/mm3, and the build rate, from 12 to 36 cm3/h. The manufactured coupons were analyzed by X-ray diffractometry, transmission, and scanning electron microscopy. It was found that the greater influence observed on the microstructure and texture development was caused by the value of laser power, while the lowest, by that of hatching space. Based on the results obtained, the processing optimization strategy aimed at improving the density, superelastic, and fatigue properties of the L-PBF manufactured Ti-18Zr-14Nb alloy was proposed.

Synthesis of barium and strontium carbonate crystals with unusual morphologies using an organic additive

NASA Astrophysics Data System (ADS)

Chen, Long; Jiang, Jizhong; Bao, Zuben; Pan, Jian; Xu, Weibing; Zhou, Lili; Wu, Zhigang; Chen, Xu

2013-12-01

In this paper, strontium carbonate (SrCO3) and barium carbonate (BaCO3) crystals were synthesized in the presence of an organic additive-hexamethylenetetramine (HMT) using two CO2 sources. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the products. The results showed that the morphologies of orthorhombic strontianite SrCO3 transformed from branch-like to flower-like, and to capsicum-like at last, while the morphologies of BaCO3 change from fiber-like to branchlike, and to rod-like finally with an increase of the molar ratio HMT/Sr2+ and HMT/Ba2+ from 0.2 to 10 using ammonium carbonate as CO2 source. When using diethyl carbonate instead of ammonium carbonate as CO2 source, SrCO3 flowers aggregated by rods and BaCO3 shuttles were formed. The possible formation mechanisms of SrCO3 and BaCO3 crystals obtained in different conditions were also discussed.

Hierarchical macro-mesoporous structures in the system TiO{sub 2}-Al{sub 2}O{sub 3}, obtained by hydrothermal synthesis using Tween-20 as a directing agent

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

Garcia-Benjume, M.L.; Espitia-Cabrera, M.I.; Contreras-Garcia, M.E., E-mail: eucontre@zeus.umich.mx

2009-12-15

Macro-mesoporous powders of titania, alumina, and mixed titania-20%alumina systems were obtained by hydrothermal synthesis employing surfactant Tween-20 as structural directing agent in order to promote the textural properties of titania. The effect of the alumina in the titania phase and on textural properties was analyzed. The obtained powders presented a macroporous channel structure that was characterized by X-ray diffractometry, scanning and transmission electron microscopy, N{sub 2} adsorption-desorption analysis, pore size distribution, Fourier transform infrared spectrometry, and thermogravimetric analysis. It was found that alumina content retarded the anatase phase crystallization and increased the Brunauer-Emmet-Teller surface area from 136 to 210 m{supmore » 2}/g. The powders calcined at 400 deg. C are thermally stable and possess an interconnected macro-mesoporous hierarchical structure; the results indicate that this synthesis can be employed to prepare mixed titania-alumina with good textural properties.« less

Preparation of CMC-modified melamine resin spherical nano-phase change energy storage materials.

PubMed

Hu, Xiaofeng; Huang, Zhanhua; Zhang, Yanhua

2014-01-30

A novel carboxymethyl cellulose (CMC)-modified melamine-formaldehyde (MF) phase change capsule with excellent encapsulation was prepared by in situ polymerization. Effects of CMC on the properties of the capsules were studied by Fourier transformation infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). The results showed that the CMC-modified capsules had an average diameter of about 50nm and good uniformity. The phase change enthalpy of the capsules was increased and the cracking ratio decreased by incorporating a suitable amount of CMC. The optimum phase change enthalpy of the nanocapsules was 83.46J/g, and their paraffin content was 63.1%. The heat resistance of the capsule shells decreased after CMC modification. In addition, the nanocapsule cracking ratio of the nanocapsules was 11.0%, which is highly attractive for their application as nano phase change materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

Change Spectrum Characteristics Modification of Films Deposited by Magnetron Sputtering with the Assistance of Argon Ions Beam

NASA Astrophysics Data System (ADS)

Umnov, S.; Asainov, O.

2015-04-01

Thin aluminum films were prepared using the method of magnetron sputtering with and without argon ion beam assistance. The influence of argon ion beam on the reflectivity in the UV range and the structure of aluminum films was studied. The structure of the films was studied by transmission electron microscopy (TEM), X-ray diffractometry (XRD) and atomic- force microscope (AFM). The study has shown that the films deposed with the assistance of the argon ion beam have more significant microstresses associated with an increase of crystallites microstructure defects as compared to the films deposed without ion assistance. Comparison of the measured reflectivity of aluminum films deposed without and with the assistance of the ion beam has shown that the films characterized by a higher level of microstructure def ects have increased reflectivity in the UV range. The studies suggest that the defects of thin aluminum films crystal structure influence its optical properties.

Encapsulation of Ethylene Gas into Granular Cold-Water-Soluble Starch: Structure and Release Kinetics.

PubMed

Shi, Linfan; Fu, Xiong; Tan, Chin Ping; Huang, Qiang; Zhang, Bin

2017-03-15

Ethylene gas was introduced into granular cold-water-soluble (GCWS) starches using a solid encapsulation method. The morphological and structural properties of the novel inclusion complexes (ICs) were characterized using scanning electron microscopy, X-ray diffractometry, and Raman spectroscopy. The V-type single helix of GCWS starches was formed through controlled gelatinization and ethanol precipitation and was approved to host ethylene gas. The controlled release characteristics of ICs were also investigated at various temperature and relative humidity conditions. Avrami's equation was fitted to understand the release kinetics and showed that the release of ethylene from the ICs was accelerated by increasing temperature or RH and was decelerated by increased degree of amylose polymerization. The IC of Hylon-7 had the highest ethylene concentration (31.8%, w/w) among the five starches, and the IC of normal potato starch showed the best controlled release characteristics. As a renewable and inexpensive material, GCWS starch is a desirable solid encapsulation matrix with potential in agricultural and food applications.

Synthesization, Characterization, and in Vitro Evaluation of Cytotoxicity of Biomaterials Based on Halloysite Nanotubes.

PubMed

Sánchez-Fernández, Antonio; Peña-Parás, Laura; Vidaltamayo, Román; Cué-Sampedro, Rodrigo; Mendoza-Martínez, Ana; Zomosa-Signoret, Viviana C; Rivas-Estilla, Ana M; Riojas, Paulina

2014-12-04

Halloysite is an aluminosilicate clay that has been widely used for controlled drug delivery, immobilization of enzymes, and for the capture of circulating tumor cells (CTCs). Surface modification of halloysite by organosilanes has been explored to improve their properties. In this study halloysite clay nanotubes (HNTs) were functionalized by two different organosilanes: Trimethoxy(propyl)silane (TMPS), and Triethoxy(octyl)silane (EOS). Untreated and modified samples were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetrical analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Results showed a strong interaction of organosilanes with the chemical groups present in HNTs. Biocompatibility and cytotoxicity of these nanomaterials were determined using C6 rat glioblastoma cells. Our results indicate that prior to functionalization, HNTs show a high biocompatibility and low cytotoxicity. However, HNTs functionalized with EOS and TMPS showed high cytotoxicity by inducing apoptosis. These results allow the identification of potential applications in biomedical areas for HNTs.

Synthesization, Characterization, and in Vitro Evaluation of Cytotoxicity of Biomaterials Based on Halloysite Nanotubes

PubMed Central

Sánchez-Fernández, Antonio; Peña-Parás, Laura; Vidaltamayo, Román; Cué-Sampedro, Rodrigo; Mendoza-Martínez, Ana; Zomosa-Signoret, Viviana C.; Rivas-Estilla, Ana M.; Riojas, Paulina

2014-01-01

Halloysite is an aluminosilicate clay that has been widely used for controlled drug delivery, immobilization of enzymes, and for the capture of circulating tumor cells (CTCs). Surface modification of halloysite by organosilanes has been explored to improve their properties. In this study halloysite clay nanotubes (HNTs) were functionalized by two different organosilanes: Trimethoxy(propyl)silane (TMPS), and Triethoxy(octyl)silane (EOS). Untreated and modified samples were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetrical analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Results showed a strong interaction of organosilanes with the chemical groups present in HNTs. Biocompatibility and cytotoxicity of these nanomaterials were determined using C6 rat glioblastoma cells. Our results indicate that prior to functionalization, HNTs show a high biocompatibility and low cytotoxicity. However, HNTs functionalized with EOS and TMPS showed high cytotoxicity by inducing apoptosis. These results allow the identification of potential applications in biomedical areas for HNTs. PMID:28788274

Characterization of the bioactive and mechanical behavior of dental ceramic/sol-gel derived bioactive glass mixtures.

PubMed

Abbasi, Zahra; Bahrololoum, Mohammad E; Bagheri, Rafat; Shariat, Mohammad H

2016-02-01

Dental ceramics can be modified by bioactive glasses in order to develop apatite layer on their surface. One of the benefits of such modification is to prolong the lifetime of the fixed dental prosthesis by preventing the formation of secondary caries. Dental ceramic/sol-gel derived bioactive glass mixture is one of the options for this modification. In the current study, mixtures of dental ceramic/bioactive glass with different compositions were successfully produced. To evaluate their bioactive behavior, prepared samples were immersed in a simulated body fluid at various time intervals. The prepared and soaked specimens were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Since bioactive glasses have deleterious effects on the mechanical properties of dental ceramics, 3-point bending tests were used to evaluate the flexural strength, flexural strain, tangent modulus of elasticity and Weibull modulus of the specimens in order to find the optimal relationship between mechanical and bioactive properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Capillary optics for radiation focusing

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

Peurrung, A.J.; Reeder, P.L.; Bliss, M.

Capillary lens technology may ultimately bring benefits to neutron and x-ray-based science like conventional lenses with visible light. Although the technology is not yet 10 years old, these lenses have already had a significant impact in engineering, science, and medicine. Capillary lenses are advantageous when it is desirable to increase the radiation flux at a location without regard to its angular divergence. PNNL has worked to improve the technology in several ways. A single, optimally tapered capillary was manufactured, which allows intensity gains of a factor of 270 for an initially parallel, incident x-ray beam. Feasibility of constructing neutron lensesmore » using {sup 58}Ni (particularly effective at reflecting neutrons) has been explored. Three applications for capillary optics have been identified and studied: neutron telescope, Gandolphi x-ray diffractometry, and neutron radiotherapy. A brief guide is given for determining which potential applications are likely to be helped by capillary optics.« less

In vitro biocompatibility of magnesium-incorporated submicro-porous titanium oxide surface produced by hydrothermal treatment

NASA Astrophysics Data System (ADS)

Park, Jin-Woo; Kim, Youn-Jeong; Jang, Je-Hee; An, Chang-Hyeon

2010-11-01

This study investigated the surface characteristics and in vitro biocompatibility of titanium (Ti) oxide surface incorporating magnesium ions (Mg), produced by hydrothermal treatment using an alkaline Mg-containing solution, for future biomedical applications. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and optical profilometry. Mouse calvaria-derived osteoblastic cell (MC3T3-E1) attachment, spreading, proliferation, alkaline phosphatase (ALP) activity, and osteoblastic gene expression on Mg-containing surfaces were compared with untreated Ti surfaces. Hydrothermal treatment resulted in Mg-incorporated Ti oxide layer with submicro-porous surface structures approximately 2 μm in thickness. ICP-AES analysis revealed Mg ions release from treated surfaces into the solution. The Mg-incorporated surface displayed significantly increased cellular attachment and ALP activity compared with untreated surface ( p < 0.05), and supported better cell spreading. Real-time polymerase chain reaction analysis showed notably higher mRNA expression of the osteoblast transcription factor genes (Dlx5, Runx2) and the osteoblast phenotype genes (ALP, bone sialoprotein and osteocalcin) in cells grown on the Mg-incorporated surfaces than untreated surfaces. These results demonstrate that the Mg-incorporated submicro-porous Ti oxide surface produced by hydrothermal treatment may improve implant osseointegration by enhancing the attachment, spreading and differentiation of osteoblastic cells.

Enhancement of the dissolution rate and bioavailability of fenofibrate by a melt-adsorption method using supercritical carbon dioxide

PubMed Central

Cha, Kwang-Ho; Cho, Kyung-Jin; Kim, Min-Soo; Kim, Jeong-Soo; Park, Hee Jun; Park, Junsung; Cho, Wonkyung; Park, Jeong-Sook; Hwang, Sung-Joo

2012-01-01

Background: The aim of this study was to enhance the bioavailability of fenofibrate, a poorly water-soluble drug, using a melt-adsorption method with supercritical CO2. Methods: Fenofibrate was loaded onto Neusilin® UFL2 at different weight ratios of fenofibrate to Neusilin UFL2 by melt-adsorption using supercritical CO2. For comparison, fenofibrate-loaded Neusilin UFL2 was prepared by solvent evaporation and hot melt-adsorption methods. The fenofibrate formulations prepared were characterized by differential scanning calorimetry, powder x-ray diffractometry, specific surface area, pore size distribution, scanning electron microscopy, and energy-dispersive x-ray spectrometry. In vitro dissolution and in vivo bioavailability were also investigated. Results: Fenofibrate was distributed into the pores of Neusilin UFL2 and showed reduced crystal formation following adsorption. Supercritical CO2 facilitated the introduction of fenofibrate into the pores of Neusilin UFL2. Compared with raw fenofibrate, fenofibrate from the prepared powders showed a significantly increased dissolution rate and better bioavailability. In particular, the area under the drug concentration-time curve and maximal serum concentration of the powders prepared using supercritical CO2 were 4.62-fold and 4.52-fold greater than the corresponding values for raw fenofibrate. Conclusion: The results of this study highlight the usefulness of the melt-adsorption method using supercritical CO2 for improving the bioavailability of fenofibrate. PMID:23118538

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

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

Ferencz, Zs.; Szabados, M.; Varga, G.

2016-01-15

A mechanochemical method (grinding the components without added water – dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution – wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure wasmore » also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic–inorganic nanocomposites: LDHs intercalated with amino acid anions. - Graphical abstract: Amino acid anion-Ca(II)Fe(III)-LDHs were successfully prepared by a two-step milling procedure. - Highlights: • Synthesis of pristine and amino acid intercalated CaFe-LDHs by two-step milling. • Identifying the optimum synthesis and intercalation parameters. • Characterisation of the samples with a range of instrumental methods.« less

Oxidation study of coated Crofer 22 APU steel in dry oxygen

NASA Astrophysics Data System (ADS)

Molin, Sebastian; Chen, Ming; Hendriksen, Peter Vang

2014-04-01

The effect of a dual layer coating composed of a layer of a Co3O4 and a layer of a La0.85Sr0.15MnO3/Co3O4 mixture on the high temperature corrosion of the Crofer 22 APU alloy is reported. Oxidation experiments were performed in dry oxygen at three temperatures: 800 °C, 850 °C and 900 °C for periods up to 1000 h. Additionally at 850 °C a 5000 h long oxidation test was performed to evaluate longer term suitability of the proposed coating. Corrosion kinetics were evaluated by measuring mass gain during oxidation. The corrosion kinetics for the coated samples are analyzed in terms of a parabolic rate law. Microstructural features were investigated by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffractometry. The coating is effective in reducing the corrosion rate and in ensuring long lifetime of coated alloys. The calculated activation energy for the corrosion process is around 1.8 eV. A complex Co-Mn-Cr spinel is formed caused by diffusion of Cr and Mn from the alloy into the Co3O4 coating and by additional diffusion of Mn from the LSM layer. Adding a layer of LSM/Co3O4, acting as an additional Mn source, on top of the cobalt spinel is beneficial for the improved corrosion resistance.

The effect of nanoparticles size on photocatalytic and antimicrobial properties of Ag-Pt/TiO2 photocatalysts

NASA Astrophysics Data System (ADS)

Zielińska-Jurek, Anna; Wei, Zhishun; Wysocka, Izabela; Szweda, Piotr; Kowalska, Ewa

2015-10-01

Ag-Pt-modified TiO2 nanocomposites were synthesized using the sol-gel method. Bimetallic modified TiO2 nanoparticles exhibited improved photocatalytic activity under visible-light irradiation, better than monometallic Ag/TiO2 and Pt/TiO2 nanoparticles (NPs). All modified powders showed localized surface plasmon resonance (LSPR) in visible region. The photocatalysts' characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption (BET method for specific surface area) showed that sample with the highest photocatalytic activity had anatase structure, about 93 m2/g specific surface area, maximum plasmon absorption at ca. 420 nm and contained small NPs of silver of 6 nm and very fine platinum NPs of 3 nm. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/vis light irradiation. It was found that size of platinum was decisive for the photocatalytic activity under visible light irradiation, i.e., the smaller Pt NPs were, the higher was photocatalytic activity. While, antimicrobial activities, estimated for bacteria Escherichia coli and Staphylococcus aureus, and pathogenic fungi belonging to Candida family, were only observed for photocatalysts containing silver, i.e., Ag/TiO2 and Ag-Pt/TiO2 nanocomposites.

Surface modification using the biomimetic method in alumina-zirconia porous ceramics obtained by the replica method.

PubMed

Silva, André D R; Rigoli, Willian R; Osiro, Denise; Mello, Daphne C R; Vasconcellos, Luana M R; Lobo, Anderson O; Pallone, Eliria M J A

2018-01-12

The modification of biomaterials approved by the Food and Drug Administration could be an alternative to reduce the period of use in humans. Porous bioceramics are widely used as support structures for bone formation and repair. This composite has essential characteristics for an implant, including good mechanical properties, high chemical stability, biocompatibility and adequate aesthetic appearance. Here, three-dimensional porous scaffolds of Al 2 O 3 containing 5% by volume of ZrO 2 were produced by the replica method. These scaffolds had their surfaces chemically treated with phosphoric acid and were coated with calcium phosphate using the biomimetic method simulated body fluid (SBF, 5×) for 14 days. The scaffolds, before and after biomimetic coating, were characterized mechanically, morphologically and structurally by axial compression tests, scanning electron microscopy, microtomography, apparent porosity, X-ray diffractometry, near-infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy and reactivity. The in vitro cell viability and formation of mineralization nodules were used to identify the potential for bone regeneration. The produced scaffols after immersion in SBF were able to induce the nodules formation. These characteristics are advantaged by the formation of different phases of calcium phosphates on the material surface in a reduced incubation period. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

Antibacterial activity and cytotoxicity of multi-walled carbon nanotubes decorated with silver nanoparticles

PubMed Central

Seo, Youngmin; Hwang, Jangsun; Kim, Jieun; Jeong, Yoon; Hwang, Mintai P; Choi, Jonghoon

2014-01-01

Recently, various nanoscale materials, including silver (Ag) nanoparticles, have been actively studied for their capacity to effectively prevent bacterial growth. A critical challenge is to enhance the antibacterial properties of nanomaterials while maintaining their biocompatibility. The conjugation of multiple nanomaterials with different dimensions, such as spherical nanoparticles and high-aspect-ratio nanotubes, may increase the target-specific antibacterial capacity of the consequent nanostructure while retaining an optimal biocompatibility. In this study, multi-walled carbon nanotubes (MWCNTs) were treated with a mixture of acids and decorated with Ag nanoparticles via a chemical reduction of Ag cations by ethanol solution. The synthesized Ag-MWCNT complexes were characterized by transmission electron microscopy, X-ray diffractometry, and energy-dispersive X-ray spectroscopy. The antibacterial function of Ag-MWCNTs was evaluated against Methylobacterium spp. and Sphingomonas spp. In addition, the biocompatibility of Ag-MWCNTs was evaluated using both mouse liver hepatocytes (AML 12) and human peripheral blood mononuclear cells. Finally, we determined the minimum amount of Ag-MWCNTs required for a biocompatible yet effective antibacterial treatment modality. We report that 30 μg/mL of Ag-MWCNTs confers antibacterial functionality while maintaining minimal cytotoxicity toward both human and animal cells. The results reported herein would be beneficial for researchers interested in the efficient preparation of hybrid nanostructures and in determining the minimum amount of Ag-MWCNTs necessary to effectively hinder the growth of bacteria. PMID:25336943

Morphology and structure features of ZnAl{sub 2}O{sub 4} spinel nanoparticles prepared by matrix-isolation-assisted calcination

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

Du, Xuelian, E-mail: xueliandu@126.com; Li, Liqiang; Zhang, Wenxing

2015-01-15

Graphical abstract: The substrate ZnO as the isolation medium is effective in preventing the sintering and agglomeration of ZnAl{sub 2}O{sub 4} nanoparticles, and it also prevents their contamination. High purity, well-dispersed, and single-crystal ZnAl{sub 2}O{sub 4} nanoparticles with 3.72 eV band gap were obtained. - Abstract: Well-dispersed ZnAl{sub 2}O{sub 4} spinel nanoparticles with an average crystalline size of 25.7 nm were synthesized successfully and easily by polymer-network and matrix-isolation-assisted calcination. The product microstructure and features were investigated by X-ray diffractometry, thermogravimetric and differential thermal analysis, Fourier transform-infrared spectroscopy, N{sub 2} adsorption–desorption isotherms, and energy dispersive X-ray spectra. The morphology andmore » optical performance of the as-prepared ZnAl{sub 2}O{sub 4} nanoparticles were characterized by scanning electron microscope, transmission electron microscopy, and photoluminescence spectrometer. Experimental results indicate that excess ZnO acted as the isolation medium is effective in preventing the sintering and agglomeration of ZnAl{sub 2}O{sub 4} nanoparticles, and it also prevents their contamination. Then, high purity and well-dispersed ZnAl{sub 2}O{sub 4} nanoparticles with single-crystal structure were obtained.« less

Synthesis of magnetic mesoporous metal-organic framework-5 for the effective enrichment of malachite green and crystal violet in fish samples.

PubMed

Zhou, Zhihui; Fu, Yanqing; Qin, Qian; Lu, Xin; Shi, Xianzhe; Zhao, Chunxia; Xu, Guowang

2018-07-27

A novel, magnetic and mesoporous Fe 3 O 4 @PEI-MOF-5 material was synthesized for the effective enrichment of malachite green (MG) and crystal violet (CV) in fish samples. The Fe 3 O 4 @PEI-MOF-5 material was prepared by a facile two-step solvothermal approach in which Fe 3 O 4 @PEI and MOF-5 were connected through chemical bonds. Characterization of the newly synthesized Fe 3 O 4 @PEI-MOF-5 material was performed by Fourier transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. This new material was determined to have high magnetization and chemical stability, a large surface area and a distinctive morphology. An effective enrichment and detection method for MG and CV was subsequently developed by combining the Fe 3 O 4 @PEI-MOF-5 material with ultra-high-performance liquid chromatography-tandem mass spectrometry. The linearity ranges of this approach for MG and CV were 1-500ng/mL and 0.25-500ng/mL, respectively, with correlation coefficients (R 2 ) of 0.999. The limits of detection (LODs) of the method for MG and CV were 0.30ng/mL and 0.08ng/mL, respectively, indicating that the Fe 3 O 4 @PEI-MOF-5 material had good adsorption properties for MG and CV. Fe 3 O 4 @PEI-MOF-5 can be expected to also provide efficient enrichment of MG and CV in other complex matrices. Copyright © 2018 Elsevier B.V. All rights reserved.

Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

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

Zhai, Bao-gai; Ma, Qing-lan; School of Electronics and Information, Nantong University, Jiangsu 226019

Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of themore » absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.« less

A Compact X-Ray System for Support of High Throughput Crystallography

NASA Technical Reports Server (NTRS)

Ciszak, Ewa; Gubarev, Mikhail; Gibson, Walter M.; Joy, Marshall K.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Standard x-ray systems for crystallography rely on massive generators coupled with optics that guide X-ray beams onto the crystal sample. Optics for single-crystal diffractometry include total reflection mirrors, polycapillary optics or graded multilayer monochromators. The benefit of using polycapillary optic is that it can collect x-rays over tile greatest solid angle, and thus most efficiently, utilize the greatest portion of X-rays emitted from the Source, The x-ray generator has to have a small anode spot, and thus its size and power requirements can be substantially reduced We present the design and results from the first high flux x-ray system for crystallography that combine's a microfocus X-ray generator (40microns FWHM Spot size at a power of 45 W) and a collimating, polycapillary optic. Diffraction data collected from small test crystals with cell dimensions up to 160A (lysozyme and thaumatin) are of high quality. For example, diffraction data collected from a lysozyme crystal at RT yielded R=5.0% for data extending to 1.70A. We compare these results with measurements taken from standard crystallographic systems. Our current microfocus X-ray diffraction system is attractive for supporting crystal growth research in the standard crystallography laboratory as well as in remote, automated crystal growth laboratory. Its small volume, light-weight, and low power requirements are sufficient to have it installed in unique environments, i.e.. on-board International Space Station.

Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in Escherichia coli and M13 bacteriophage

PubMed Central

Jin, Su-Eon; Hwang, Woochul; Lee, Hyo Jung; Jin, Hyo-Eon

2017-01-01

Metal oxide (MO) nanoparticles have been studied as nano-antibiotics due to their antimicrobial activities even in antibiotic-resistant microorganisms. We hypothesized that a hybrid system of dual UV irradiation and MO nanoparticles would have enhanced antimicrobial activities compared with UV or MO nanoparticles alone. In this study, nanoparticles of ZnO, ZnTiO3, MgO, and CuO were selected as model nanoparticles. A dual UV collimated beam device of UV-A and UV-C was developed depending upon the lamp divided by coating. Physicochemical properties of MO nanoparticles were determined using powder X-ray diffractometry (PXRD), Brunauer-Emmett-Teller analysis, and field emission-scanning electron microscopy with energy-dispersive X-ray spectroscopy. Atomic force microscopy with an electrostatic force microscopy mode was used to confirm the surface topology and electrostatic characteristics after dual UV irradiation. For antimicrobial activity test, MO nanoparticles under dual UV irradiation were applied to Escherichia coli and M13 bacteriophage (phage). The UV-A and UV-C showed differential intensities in the coated and uncoated areas (UV-A, coated = uncoated; UV-C, coated ≪ uncoated). MO nanoparticles showed sharp peaks in PXRD patterns, matched to pure materials. Their primary particle sizes were less than 100 nm with irregular shapes, which had an 8.6~25.6 m2/g of specific surface area with mesopores of 22~262 nm. The electrostatic properties of MO nanoparticles were modulated after UV irradiation. ZnO, MgO, and CuO nanoparticles, except ZnTiO3 nanoparticles, showed antibacterial effects on E. coli. Antimicrobial effects on E. coli and phages were also enhanced after cyclic exposure of dual UV and MO nanoparticle treatment using the uncoated area, except ZnO nanoparticles. Our results demonstrate that dual UV-MO nanoparticle hybrid system has a potential for disinfection. We anticipate that it can be developed as a next-generation disinfection system in pharmaceutical industries and water purification systems. PMID:29138562

Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in Escherichia coli and M13 bacteriophage.

PubMed

Jin, Su-Eon; Hwang, Woochul; Lee, Hyo Jung; Jin, Hyo-Eon

2017-01-01

Metal oxide (MO) nanoparticles have been studied as nano-antibiotics due to their antimicrobial activities even in antibiotic-resistant microorganisms. We hypothesized that a hybrid system of dual UV irradiation and MO nanoparticles would have enhanced antimicrobial activities compared with UV or MO nanoparticles alone. In this study, nanoparticles of ZnO, ZnTiO 3 , MgO, and CuO were selected as model nanoparticles. A dual UV collimated beam device of UV-A and UV-C was developed depending upon the lamp divided by coating. Physicochemical properties of MO nanoparticles were determined using powder X-ray diffractometry (PXRD), Brunauer-Emmett-Teller analysis, and field emission-scanning electron microscopy with energy-dispersive X-ray spectroscopy. Atomic force microscopy with an electrostatic force microscopy mode was used to confirm the surface topology and electrostatic characteristics after dual UV irradiation. For antimicrobial activity test, MO nanoparticles under dual UV irradiation were applied to Escherichia coli and M13 bacteriophage (phage). The UV-A and UV-C showed differential intensities in the coated and uncoated areas (UV-A, coated = uncoated; UV-C, coated ≪ uncoated). MO nanoparticles showed sharp peaks in PXRD patterns, matched to pure materials. Their primary particle sizes were less than 100 nm with irregular shapes, which had an 8.6~25.6 m 2 /g of specific surface area with mesopores of 22~262 nm. The electrostatic properties of MO nanoparticles were modulated after UV irradiation. ZnO, MgO, and CuO nanoparticles, except ZnTiO 3 nanoparticles, showed antibacterial effects on E. coli . Antimicrobial effects on E. coli and phages were also enhanced after cyclic exposure of dual UV and MO nanoparticle treatment using the uncoated area, except ZnO nanoparticles. Our results demonstrate that dual UV-MO nanoparticle hybrid system has a potential for disinfection. We anticipate that it can be developed as a next-generation disinfection system in pharmaceutical industries and water purification systems.

Phase transition behavior of (K,Na)NbO3-based high-performance lead-free piezoelectric ceramic composite with different phase compositions depending on Na fraction

NASA Astrophysics Data System (ADS)

Yamada, Hideto; Matsuoka, Takayuki; Yamazaki, Masato; Ohbayashi, Kazushige; Ida, Takashi

2018-01-01

The structures of the main (K1- x Na x )NbO3 perovskite in a high-performance lead-free piezoelectric ceramic composite (K1- x Na x )0.86Ca0.04Li0.02Nb0.85O3-δ-K0.85Ti0.85Nb1.15O5-BaZrO3-MgO-Fe2O3 (x = 0.52 and 0.70) with trace amounts of LiMgFeTiO4 inverse spinel and (Li,K)2(Mg,Fe,Ti,Nb)6O13 layered structure have been investigated by transmission electron microscopy (TEM) and synchrotron powder X-ray diffractometry (XRD) with varying temperatures. The bright-field TEM images have shown tetragonal 90°-domain contrasts at 80 and 40 °C, and the XRD profile has been simulated by adding an average structure of two differently oriented tetragonal structures bound by a 90°-domain wall for the x = 0.52 sample. Aggregates of tilted NbO6 nanodomains have been observed in a high-resolution TEM image, and the crossover of P4mm-Amm2 features from 60 to 20 °C and diffuse 2 × 2 × 2 superlattice reflections of the tilted NbO6 Imm2 structure have been observed in XRD data for the x = 0.70 sample.

W{sub 18}O{sub 49} nanorods decorated with Ag/AgCl nanoparticles as highly-sensitive gas-sensing material and visible-light-driven photocatalyst

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

Sun Shibin; Chang Xueting, E-mail: xuetingchang@yahoo.cn; Dong Lihua

2011-08-15

A novel gas-sensing material and photocatalyst was successfully obtained by decorating Ag/AgCl nanoparticles on the W{sub 18}O{sub 49} nanorods through a clean photochemical route. The as-prepared samples were characterized using combined techniques of X-ray diffractometry, electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy. Gas-sensing measurements indicate that the Ag/AgCl/W{sub 18}O{sub 49} NRs sensors exhibit superior reducing gas-sensing properties to those of bare W{sub 18}O{sub 49} NRs, and they are highly selective and sensitive to NH{sub 3}, acetone, and H{sub 2}S with short response and recovery times. The Ag/AgCl/W{sub 18}O{sub 49} NRs photocatlysts also possess higher photocatalytic performance thanmore » bare W{sub 18}O{sub 49} NRs for degradation of methyl orange under simulated sunlight irradiation. Possible mechanisms concerning the enhancement of gas-sensing and photocatalytic activities of the Ag/AgCl/W{sub 18}O{sub 49} NRs composite were proposed. - Graphical Abstract: The Ag/AgCl nanoparticles adhered well to the W{sub 18}O{sub 49} nanorod. The Ag could act as transfer center of the photoexcited carriers, prohibiting their recombinations in both W{sub 18}O{sub 49} and AgCl. Highlights: > Ag/AgCl/W{sub 18}O{sub 49} NRs were successfully obtained via a clean photochemical route. > The Ag/AgCl nanoparticles decorated on the W{sub 18}O{sub 49} NRs possessed cladding structure. > The Ag/AgCl/W{sub 18}O{sub 49} NRs exhibited excellent gas-sensing and photocatalytic properties.« less

X-ray ptychography

NASA Astrophysics Data System (ADS)

Pfeiffer, Franz

2018-01-01

X-ray ptychographic microscopy combines the advantages of raster scanning X-ray microscopy with the more recently developed techniques of coherent diffraction imaging. It is limited neither by the fabricational challenges associated with X-ray optics nor by the requirements of isolated specimen preparation, and offers in principle wavelength-limited resolution, as well as stable access and solution to the phase problem. In this Review, we discuss the basic principles of X-ray ptychography and summarize the main milestones in the evolution of X-ray ptychographic microscopy and tomography over the past ten years, since its first demonstration with X-rays. We also highlight the potential for applications in the life and materials sciences, and discuss the latest advanced concepts and probable future developments.

An x-ray diffraction study of microstructural deformation induced by cyclic loading of selected steel

NASA Astrophysics Data System (ADS)

Fourspring, Patrick Michael

X-ray double crystal diffractometry (XRDCD) and X-ray scanning diffractometry (XRSD) were used to assess cyclic microstructural deformation in a face centered cubic (fcc) steel (AISI304) and a body centered cubic (bcc) steel (SA508 class 2). The objectives of the investigation were to determine if X-ray diffraction could be used effectively to monitor cyclic microstructural deformation in polycrystalline Fe alloys and to study the distribution of the microstructural deformation induced by cyclic loading in these alloys. The approach used in the investigation was to induce fatigue damage in a material and to characterize the resulting microstructural deformation at discrete fractions of the fatigue life of the material. Also, characterization of microstructural deformation was carried out to identify differences in the accumulation of damage from the surface to the bulk, focusing on the following three regions: near surface (0-10 mum), subsurface (10-300 mum), and bulk. Characterization of the subsurface region was performed only on the AISI304 material because of the limited availability of the SA508 material. The results from the XRDCD data indicate a measurable change induced by fatigue from the initial state to subsequent states of both the AISI304 and the SA508 materials. The results from the XRSD data show similar but less coherent trends than the results from the XRDCD data. Therefore, the XRDCD technique was shown to be sensitive to the microstructural deformation caused by fatigue in steels; thus, the technique can be used to monitor fatigue damage in steels. In addition, for the AISI304 material, the level of cyclic microstructural deformation in the bulk material was found to be greater than the level in the near surface material. In contrast, previous investigations have shown that the deformation is greater in the near surface than the bulk for Al alloys and bcc Fe alloys.

A two-dimensional polymer synthesized at the air/water interface.

PubMed

Schlüter, A Dieter; Müller, Vivian; Hinaut, Antoine; Moradi, Mina; Baljozovic, Milos; Jung, Thomas; Shahgaldian, Patrick; Möhwald, Helmuth; Hofer, Gregor; Kröger, Martin; King, Benjamin; Meyer, Ernst; Glatzel, Thilo

2018-06-11

A trifunctional, partially fluorinated anthracene-substituted triptycene monomer is spread at the air/water interface into a monolayer, which is transformed into a long-range ordered 2D polymer by irradiation with a standard ultraviolet lamp using 365 nm light. The polymer is analyzed by Brewster angle microscopy directly at this interface and by scanning tunneling microscopy measurements and non-contact atomic force microscopy (nc-AFM), both after transfer from below the interface onto highly oriented pyrolytic graphite and then into ultra-high vacuum. Both methods confirm a network structure, the lattice parameters of which are virtually identical to a structural model network based on X-ray diffractometry of a closely related 2D polymer unequivocally established in a single crystal. The nc-AFM images are obtained with unprecedentedly high resolution and prove long-range order over areas of at least 300 × 300 nm2. As required for a 2D polymer, the pore sizes are monodisperse, except for the regions, where the network is somewhat stretched because it spans over protrusions. Together with a previous report on the nature of the cross-links in this network, the structural information provided here leaves no doubt that a 2D polymer has been synthesized under ambient conditions at an air/water interface. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CXRO - Mi-Young Im, Staff Scientist

Science.gov Websites

X-Ray Database Zone Plate Education Nanomagnetism X-Ray Microscopy LDJIM EUV Lithography EUV Mask Publications Contact The Center for X-Ray Optics is a multi-disciplined research group within Lawrence Berkeley -Ray Optics X-Ray Database Nanomagnetism X-Ray Microscopy EUV Lithography EUV Mask Imaging

The X-ray Fluorescence Microscopy Beamline at the Australian Synchrotron

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

Paterson, D.; Jonge, M. D. de; Howard, D. L.

2011-09-09

A hard x-ray micro-nanoprobe has commenced operation at the Australian Synchrotron providing versatile x-ray fluorescence microscopy across an incident energy range from 4 to 25 keV. Two x-ray probes are used to collect {mu}-XRF and {mu}-XANES for elemental and chemical microanalysis: a Kirkpatrick-Baez mirror microprobe for micron resolution studies and a Fresnel zone plate nanoprobe capable of 60-nm resolution. Some unique aspects of the beamline design and operation are discussed. An advanced energy dispersive x-ray fluorescence detection scheme named Maia has been developed for the beamline, which enables ultrafast x-ray fluorescence microscopy.

Effect of Heat Treatment Temperature on Chemical Compositions of Extracted Hydroxyapatite from Bovine Bone Ash

NASA Astrophysics Data System (ADS)

Younesi, M.; Javadpour, S.; Bahrololoom, M. E.

2011-11-01

This article presents the effect of heat treating temperature on chemical composition of hydroxyapatite (HA) that was produced by burning bovine bone, and then heat treating the obtained bone ash at different temperatures in range of 600-1100 °C in air. Bone ash and the resulting white powder from heat treating were characterized by Fourier transformed infrared spectroscopy (FT-IR) and x-ray diffractometry (XRD). The FT-IR spectra confirmed that heat treating of bone ash at temperature of 800 °C removed the total of organic substances. x-ray diffraction analysis showed that the white powder was HA and HA was the only crystalline phase indicated in heat treating product. x-ray fluorescence analyses revealed that calcium and phosphorous were the main elements and magnesium and sodium were minor impurities of produced powder at 800 °C. The results of the energy dispersive x-ray analysis showed that Ca/P ratio in produced HA varies in range of 1.46-2.01. The resulting material was found to be thermally stable up to 1100 °C.

Quantitative X-ray Differential Interference Contrast Microscopy

NASA Astrophysics Data System (ADS)

Nakamura, Takashi

Full-field soft x-ray microscopes are widely used in many fields of sciences. Advances in nanofabrication technology enabled short wavelength focusing elements with significantly improved spatial resolution. In the soft x-ray spectral region, samples as small as 12 nm can be resolved using micro zone-plates as the objective lens. In addition to conventional x-ray microscopy in which x-ray absorption difference provides the image contrast, phase contrast mechanisms such as differential phase contrast (DIC) and Zernike phase contrast have also been demonstrated These phase contrast imaging mechanisms are especially attractive at the x-ray wavelengths where phase contrast of most materials is typically 10 times stronger than the absorption contrast. With recent progresses in plasma-based x- ray sources and increasing accessibility to synchrotron user facilities, x-ray microscopes are quickly becoming standard measurement equipment in the laboratory. To further the usefulness of x-ray DIC microscopy this thesis explicitly addresses three known issues with this imaging modality by introducing new techniques and devices First, as opposed to its visible-light counterpart, no quantitative phase imaging technique exists for x-ray DIC microscopy. To address this issue, two nanoscale x-ray quantitative phase imaging techniques, using exclusive OR (XOR) patterns and zone-plate doublets, respectively, are proposed. Unlike existing x-ray quantitative phase imaging techniques such as Talbot interferometry and ptychography, no dedicated experimental setups or stringent illumination coherence are needed for quantitative phase retrieval. Second, to the best of our knowledge, no quantitative performance characterization of DIC microscopy exists to date. Therefore the imaging system's response to sample's spatial frequency is not known In order to gain in-depth understanding of this imaging modality, performance of x-ray DIC microscopy is quantified using modulation transfer function. A new illumination apparatus required for the transfer function analysis under partially coherent illumination is also proposed. Such a characterization is essential for a proper selection of DIC optics for various transparent samples under study. Finally, optical elements used for x-ray DIC microscopy are highly absorptive and high brilliance x-ray sources such as synchrotrons are generally needed for image contrast. To extend the use of x-ray DIC microscopy to a wider variety of applications, a high efficiency large numerical aperture optical element consisting of high reflective Bragg reflectors is proposed. Using Bragg reflectors, which have 70% ˜99% reflectivity at extreme ultraviolet and soft x-rays for all angles of glancing incidence, the first order focusing efficiency is expected to increase by ˜ 8 times compared to that of a typical Fresnel zone-plate. This thesis contributes to current nanoscale x-ray phase contrast imaging research and provides new insights for biological, material, and magnetic sciences

Synchrotron radiation beamline to study radioactive materials at the Photon Factory

NASA Astrophysics Data System (ADS)

Konishi, Hiroyuki; Yokoya, Akinari; Shiwaku, Hideaki; Motohashi, Haruhiko; Makita, Tomoko; Kashihara, Yasuharu; Hashimoto, Shinya; Harami, Taikan; Sasaki, Teikichi A.; Maeta, Hiroshi; Ohno, Hideo; Maezawa, Hideki; Asaoka, Seiji; Kanaya, Noriichi; Ito, Kenji; Usami, Noriko; Kobayashi, Katsumi

1996-02-01

Design and construction of a new beamline have been described. The beamline is housed in a specially designed area controlled for radioactive materials at the Photon Factory (PF) in the National Laboratory for High Energy Physics (KEK). The beamline system consists of a front-end and two branchlines. One of the branchlines is used for X-ray photoelectron spectroscopy and radiation biology in the energy range of 1.8-6 keV and the other for X-ray diffractometry and XAFS studies as well as radiation biology in the range of 4-20 keV. The former was particularly equipped for the protection against accidental scattering of radioactive materials both inside and outside of the vacuum system.

X-ray dense cellular inclusions in the cells of the green alga Chlamydomonas reinhardtii as seen by soft-x-ray microscopy

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

Stead, A.D.; Ford, T.W.; Page, A.M.

1997-04-01

Soft x-rays, having a greater ability to penetrate biological material than electrons, have the potential for producing images of intact, living cells. In addition, by using the so-called {open_quotes}water window{close_quotes} area of the soft x-ray spectrum, a degree of natural contrast is introduced into the image due to differential absorption of the wavelengths by compounds with a high carbon content compared to those with a greater oxygen content. The variation in carbon concentration throughout a cell therefore generates an image which is dependent upon the carbon density within the specimen. Using soft x-ray contact microscopy the authors have previously examinedmore » the green alga Chlamydomonas reinhardtii, and the most prominent feature of the cells are the numerous x-ray absorbing spheres, But they were not seen by conventional transmission electron microscopy. Similar structures have also been reported by the Goettingen group using their cryo transmission x-ray microscope at BESSY. Despite the fact that these spheres appear to occupy up to 20% or more of the cell volume when seen by x-ray microscopy, they are not visible by transmission electron microscopy. Given the difficulties and criticisms associated with soft x-ray contact microscopy, the present study was aimed at confirming the existence of these cellular inclusions and learning more of their possible chemical composition.« less

Investigations of interatomic interaction in InAs-InAs1-xSbx heterostructures on a base of x-ray diffractometry

NASA Astrophysics Data System (ADS)

Babjuck, T. I.; Buntar, A. G.; Shevtchuk, L. S.

2001-06-01

Hetero-transitions on a base of InAs and AnSb compounds permitted to obtain cheap light diodes and detectors with the atmosphere maximal transparency region sensibility. There is assumed simultaneously, that the phon radiation in InAs-InAs1-xSbx is not large, which positively effects on receiver parameters. Changing the composition of InAs-InAs1- xSbx solution, one may obtain the structure with the width of forbidden zone of the want of 0.35 to 0,1 eV. There is developed the heterostructures crystalline lattice parameters determining method (for substrate and film) with the DRON-3M x-ray diffractometer. There was found the nonlinear dependence of the heterostructures lattice parameter on the composition. Investigations of interatomic interaction in dependence on composition and also on the forbidden zone width Eg(x) have show, that solid solutions InAs-InAs1- xSbx may be used for the obtaining of infra-red receiver.

Nanocrystalline Ce 1- xY xO 2- x/2 (0≤ x≤0.35) Oxides via Carbonate Precipitation: Synthesis and Characterization

NASA Astrophysics Data System (ADS)

Li, Ji-Guang; Ikegami, Takayasu; Wang, Yarong; Mori, Toshiyuki

2002-10-01

A novel carbonate (co)precipitation method, employing nitrates as the starting salts and ammonium carbonate as the precipitant, has been used to synthesize nanocrystalline CeO 2 and Ce 1- xY xO 2- x/2 ( x≤0.35) solid-solutions. The resultant powders are characterized by elemental analysis, differential thermal analysis/thermogravimetry (DTA/TG), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis, and high-resolution scanning electron microscopy (HRSEM). Due to the direct formation of carbonate solid-solutions during precipitation, Ce 1- xY xO 2- x/2 solid-solution oxides are formed directly during calcination at a very low temperature of ˜300°C for 2 h. The thus-produced oxide nanopowders are essentially non-agglomerated, as revealed by BET in conjunction with XRD analysis. The solubility of YO 1.5 in CeO 2 is determined via XRD to be somewhere in the range from 27 to 35 mol%, from which a Y 2O 3-related type-C phase appears in the final product. Y 3+-doping promotes the formation of spherical nanoparticles, retards thermal decomposition of the precursors, and suppresses significantly crystallite coarsening of the oxides during calcination. The activation energy for crystallite coarsening increases gradually from 68.7 kJ mol -1 for pure CeO 2 to 138.6 kJ mol -1 for CeO 2 doped with 35 mol% YO 1.5. The dopant effects on crystallite coarsening is elaborated from the view point of solid-state chemistry.

Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline

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

Jones, Michael W. M.; Phillips, Nicholas W.; van Riessen, Grant A.

2016-08-11

Owing to its extreme sensitivity, quantitative mapping of elemental distributionsviaX-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated.

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

PubMed Central

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; Shapiro, David; Kirz, Janos; Marchesini, Stefano; Neiman, Aaron M.; Turner, Joshua J.; Jacobsen, Chris

2010-01-01

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11–13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane and freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy. PMID:20368463

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

DOE PAGES

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; ...

2010-04-20

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane andmore » freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.« less

Investigation of recrystallization of amorphous trehalose through hot-humidity stage X-ray powder diffraction.

PubMed

Jójárt-Laczkovich, Orsolya; Katona, Gábor; Aigner, Zoltán; Szabó-Révész, Piroska

2016-12-01

The aim of this work was an investigation of the physical changes of the amorphous model material spray-dried trehalose through the use of various analytical techniques and to identify a suitable, rapid method able to quantify the changes. The crystallinity changes and recrystallization process of amorphous samples were investigated by hot-humidity stage X-ray powder diffractometry (HH-XRPD) with fresh samples, conventional X-ray powder diffractometry (XRPD) used stored samples and by differential scanning calorimetry (DSC). The data from the three methods were compared and the various forms of trehalose were analysed. HH-XRPD demonstrated that the recrystallization began at 40 and 60°C up to 45% RH and at 70°C up to 30% RH into dihydrate form. At 70°C up to 60% RH the anhydrous form of trehalose appeared too. Conventional XRPD results showed, that in the 28days stored samples the dihydrate form was detected at 40°C, 50% RH. Storage at 60°C, 40% RH resulted in the appearance of the anhydrous form and at 60°C, 50% RH both polymorphic forms were detected. By carrying out the DSC measurements at different temperatures the fraction of recrystallized trehalose dihydrate was detected. The recrystallization investigated by HH-XRPD and DSC followed Avrami kinetics, the calculated rate constants of isothermal crystallization (K) were same. Both HH-XRPD and conventional XRPD was suitable for the detection of the physical changes of the amorphous model material. DSC measurements showed similar results as HH-XRPD. Primarily HH-XRPD could be suggested for prediction, because the method is fast and every changes could be studied on one sample. Copyright © 2016 Elsevier B.V. All rights reserved.

Compression-induced crystallization of amorphous indomethacin in tablets: characterization of spatial heterogeneity by two-dimensional X-ray diffractometry.

PubMed

Thakral, Naveen K; Mohapatra, Sarat; Stephenson, Gregory A; Suryanarayanan, Raj

2015-01-05

Tablets of amorphous indomethacin were compressed at 10, 25, 50, or 100 MPa using either an unlubricated or a lubricated die and stored individually at 35 °C in sealed Mylar pouches. At selected time points, tablets were analyzed by two-dimensional X-ray diffractometry (2D-XRD), which enabled us to profile the extent of drug crystallization in tablets, in both the radial and axial directions. To evaluate the role of lubricant, magnesium stearate was used as "internal" and/or "external" lubricant. Indomethacin crystallization propensity increased as a function of compression pressure, with 100 MPa pressure causing crystallization immediately after compression (detected using synchrotron radiation). However, the drug crystallization was not uniform throughout the tablets. In unlubricated systems, pronounced crystallization at the radial surface could be attributed to die wall friction. The tablet core remained substantially amorphous, irrespective of the compression pressure. Lubrication of the die wall with magnesium stearate, as external lubricant, dramatically decreased drug crystallization at the radial surface. The spatial heterogeneity in drug crystallization, as a function of formulation composition and compression pressure, was systematically investigated. When formulating amorphous systems as tablets, the potential for compression induced crystallization warrants careful consideration. Very low levels of crystallization on the tablet surface, while profoundly affecting product performance (decrease in dissolution rate), may not be readily detected by conventional analytical techniques. Early detection of crystallization could be pivotal in the successful design of a dosage form where, in order to obtain the desired bioavailability, the drug may be in a high energy state. Specialized X-ray diffractometric techniques (2D; use of high intensity synchrotron radiation) enabled detection of very low levels of drug crystallization and revealed the heterogeneity in crystallization within the tablet.

Anti-contamination device for cryogenic soft X-ray diffraction microscopy

DOE PAGES

Huang, Xiaojing; Miao, Huijie; Nelson, Johanna; ...

2011-05-01

Cryogenic microscopy allows one to view frozen hydrated biological and soft matter specimens with good structural preservation and a high degree of stability against radiation damage. We describe a liquid nitrogen-cooled anti-contamination device for cryogenic X-ray diffraction microscopy. The anti-contaminator greatly reduces the buildup of ice layers on the specimen due to condensation of residual water vapor in the experimental vacuum chamber. We show by coherent X-ray diffraction measurements that this leads to fivefold reduction of background scattering, which is important for far-field X-ray diffraction microscopy of biological specimens.

Modified extrusion-spheronization as a technique of microencapsulation for stabilization of choline bitartrate using hydrogenated soya bean oil

PubMed Central

Gangurde, Avinash Bhaskar; Sav, Ajay Kumar; Javeer, Sharadchandra Dagadu; Moravkar, Kailas K; Pawar, Jaywant N; Amin, Purnima D

2015-01-01

Introduction: Choline bitartrate (CBT) is a vital nutrient for fetal brain development and memory function. It is hygroscopic in nature which is associated with stability related problem during storage such as development of fishy odor and discoloration. Aim: Microencapsulation method was adopted to resolve the stability problem and for this hydrogenated soya bean oil (HSO) was used as encapsulating agent. Materials and Methods: Industrially feasible modified extrusion-spheronization technique was selected for microencapsulation. HSO was used as encapsulating agent, hydroxypropyl methyl cellulose E5/E15 as binder and microcrystalline cellulose as spheronization aid. Formulated pellets were evaluated for parameters such as flow property, morphological characteristics, hardness-friability index (HFI), drug content, encapsulation efficiency, and in vitro drug release. The optimized formulations were also characterized for particle size (by laser diffractometry), differential scanning calorimetry, powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy, and scanning electron microscopy. Results and Discussions: The results from the study showed that coating of 90% and 60% CBT was successful with respect to all desired evaluation parameters. Optimized formulation was kept for 6 months stability study as per ICH guidelines, and there was no change in color, moisture content, drug content, and no fishy odor was observed. Conclusion: Microencapsulated pellets of CBT using HSO as encapsulating agent were developed using modified extrusion spheronization technique. Optimized formulations, CBT 90% (F5), and CBT 60% (F10), were found to be stable for 4M and 6M, respectively, at accelerated conditions. PMID:26682198

Grid-enhanced X-ray coded aperture microscopy with polycapillary optics

PubMed Central

Sowa, Katarzyna M.; Last, Arndt; Korecki, Paweł

2017-01-01

Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10–100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy. PMID:28322316

Grid-enhanced X-ray coded aperture microscopy with polycapillary optics.

PubMed

Sowa, Katarzyna M; Last, Arndt; Korecki, Paweł

2017-03-21

Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10-100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy.

Green synthesis palladium nanoparticles mediated by white tea (Camellia sinensis) extract with antioxidant, antibacterial, and antiproliferative activities toward the human leukemia (MOLT-4) cell line.

PubMed

Azizi, Susan; Mahdavi Shahri, Mahnaz; Rahman, Heshu Sulaiman; Rahim, Raha Abdul; Rasedee, Abdullah; Mohamad, Rosfarizan

2017-01-01

Among nanoparticles used for medical applications, palladium nanoparticles (PdNPs) are among the least investigated. This study was undertaken to develop PdNPs by green synthesis using white tea (W.tea; Camellia sinensis ) extract to produce the Pd@W.tea NPs. The Pd@W.tea NPs were characterized by UV-vis spectroscopy and X-ray diffractometry, and evaluated with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The Pd@W.tea NPs were spherical (size 6-18 nm) and contained phenols and flavonoids acquired from the W.tea extract. Pd@W.tea NPs has good 1-diphenyl-2-picrylhydrazyl (DPPH), OH, and NO-scavenging properties as well as antibacterial effects toward Staphylococcus epidermidis and Escherichia coli . MTT assay showed that Pd@W.tea NPs (IC 50 =0.006 μM) were more antiproliferative toward the human leukemia (MOLT-4) cells than the W.tea extract (IC 50 =0.894 μM), doxorubicin (IC 50 =2.133 μM), or cisplatin (IC 50 =0.013 μM), whereas they were relatively innocuous for normal human fibroblast (HDF-a) cells. The anticancer cell effects of Pd@W.tea NPs are mediated through the induction of apoptosis and G2/M cell-cycle arrest.

Raman mapping of mannitol/lysozyme particles produced via spray drying and single droplet drying.

PubMed

Pajander, Jari Pekka; Matero, Sanni; Sloth, Jakob; Wan, Feng; Rantanen, Jukka; Yang, Mingshi

2015-06-01

This study aimed to investigate the effect of a model protein on the solid state of a commonly used bulk agent in spray-dried formulations. A series of lysozyme/mannitol formulations were spray-dried using a lab-scale spray dryer. Further, the surface temperature of drying droplet/particles was monitored using the DRYING KINETICS ANALYZER™ (DKA) with controllable drying conditions mimicking the spray-drying process to estimate the drying kinetics of the lysozyme/mannitol formulations. The mannitol polymorphism and the spatial distribution of lysozyme in the particles were examined using X-ray powder diffractometry (XRPD) and Raman microscopy. Partial Least Squares Discriminant Analysis was used for analyzing the Raman microscopy data. XRPD results indicated that a mixture of β-mannitol and α-mannitol was produced in the spray-drying process which was supported by the Raman analysis, whereas Raman analysis indicated that a mixture of α-mannitol and δ-mannitol was detected in the single particles from DKA. In addition Raman mapping indicated that the presence of lysozyme seemed to favor the appearance of α-mannitol in the particles from DKA evidenced by close proximity of lysozyme and mannitol in the particles. It suggested that the presence of lysozyme tend to induce metastable solid state forms upon the drying process.

Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device.

PubMed

Sanctis, Shawn; Hoffmann, Rudolf C; Eiben, Sabine; Schneider, Jörg J

2015-01-01

Tobacco mosaic virus (TMV) has been employed as a robust functional template for the fabrication of a TMV/zinc oxide field effect transistor (FET). A microwave based approach, under mild conditions was employed to synthesize stable zinc oxide (ZnO) nanoparticles, employing a molecular precursor. Insightful studies of the decomposition of the precursor were done using NMR spectroscopy and material characterization of the hybrid material derived from the decomposition was achieved using dynamic light scattering (DLS), transmission electron microscopy (TEM), grazing incidence X-ray diffractometry (GI-XRD) and atomic force microscopy (AFM). TEM and DLS data confirm the formation of crystalline ZnO nanoparticles tethered on top of the virus template. GI-XRD investigations exhibit an orientated nature of the deposited ZnO film along the c-axis. FET devices fabricated using the zinc oxide mineralized virus template material demonstrates an operational transistor performance which was achieved without any high-temperature post-processing steps. Moreover, a further improvement in FET performance was observed by adjusting an optimal layer thickness of the deposited ZnO on top of the TMV. Such a bio-inorganic nanocomposite semiconductor material accessible using a mild and straightforward microwave processing technique could open up new future avenues within the field of bio-electronics.

Direct observation of the ferroelectric polarization in the layered perovskite Bi{sub 4}Ti{sub 3}O{sub 12}

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

Urushihara, Daisuke; Asaka, Toru, E-mail: asaka.toru@nitech.ac.jp; Frontier Research Institute for Materials Science, Nagoya Institute of Technology, Nagoya 466-8555

We investigated the crystal structure and ferroelectric domains of Bi{sub 4}Ti{sub 3}O{sub 12} (BTO) by means of transmission electron microscopy (TEM) and single-crystal X-ray diffractometry. From the extinction rule, we determined that the space group in the ferroelectric phase of BTO is P1a1 rather than B2cb and B1a1 which have been proposed previously. We successfully refined the crystal structure based on the space group P1a1. The 180° and 90° ferroelectric domain structures were observed by the [001]-zone dark-field TEM imaging. In the 180° domain structure, we determined that one component of the polarization vector is parallel to the a-axis. Anmore » annular bright-field scanning transmission electron microscopy (ABF-STEM) was performed for the direct observation of the crystal structures. The ABF-STEM images displayed the contrasts with respect to every atomic position in spite of the highly distorted structure of BTO. We could evaluate the tilting and distortion of the [TiO{sub 6}] octahedra relatively. Therefore, we directly observed the ferroelectric displacements of Bi and Ti ions.« less

Nanostructured lipid carriers as novel ophthalmic delivery system for mangiferin: improving in vivo ocular bioavailability.

PubMed

Liu, Rui; Liu, Zhidong; Zhang, Chengui; Zhang, Boli

2012-10-01

The aim of this study was to develop a novel nanostructured lipid carriers (NLCs) system to improve ocular bioavailability of mangiferin (MGN) for the potential treatment of cataract. The physicochemical properties of MGN-loaded NLC (MGN-NLC) formulation were characterized by particle size, polydispersity index, zeta potential, entrapment efficiency, drug loading, morphological property, and crystalline state. in vitro characteristics were investigated by drug release from NLC system, physical stability, and corneal permeation through excised rabbit cornea. Moreover, in vivo ocular tolerability was assessed by a modified Draize test and histological microscopy. Preocular retention capability was evaluated by slit-lamp observation. Pharmacokinetic study in the aqueous humor was performed by microdialysis technique. Transmission electron microscopy depicted spherical and uniform morphology. Differential scanning calorimetry and X-ray diffractometry displayed imperfect crystalline lattice. The optimized MGN-NLC formulation exhibited a sustained drug release with 3 months stability and 4.31-fold increase of in vitro corneal permeation. Furthermore, in vivo studies exhibited a high tolerance in the ocular tissues and prolonged drug retention capacity on the corneal surface. Finally, pharmacokinetic study suggested a 5.69-fold increase of ocular bioavailability compared with MGN solution (MGN-SOL). Therefore, NLC system is a promising approach for ocular delivery of MGN. Copyright © 2012 Wiley Periodicals, Inc.

Ergonomic Synthesis Suitable for Industrial Production of Silver-Festooned Zinc Oxide Nanorods

NASA Astrophysics Data System (ADS)

Khan, G. R.; Khan, R. A.

2015-07-01

For maximizing productivity, minimizing cost, time-boxing process and optimizing human effort, a single-step, cost-effective, ultra-fast and environmentally benign synthesis suitable for industrial production of nanocrystalline ZnO, and Ag-doped ZnO has been reported in this paper. The synthesis based on microwave-supported aqueous solution method used zinc acetate dehydrate and silver nitrate as precursors for fabrication of nanorods. The synthesized products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and UV-Vis-NIR spectroscopy. The undoped and Ag-doped ZnO nanorods crystallized in a hexagonal wurtzite structure having spindle-like morphology. The blue shift occurred at absorption edge of Ag-doped ZnO around 260 nm compared to 365 nm of bulk ZnO. The red shift occurred at Raman peak site of 434 cm-1 compared to characteristic wurtzite phase peak of ZnO (437 cm-1). The bandgap energies were found to be 3.10 eV, 3.11 eV and 3.18 eV for undoped, 1% Ag-doped, and 3% Ag-doped ZnO samples, respectively. The TEM results provided average particle sizes of 17 nm, 15 nm and 13 nm for undoped, and 1% and 3% Ag-doped ZnO samples, respectively.

Mineral shock signatures in rocks from Dhala (Mohar) impact structure, Shivpuri district, Madhya Pradesh, India

NASA Astrophysics Data System (ADS)

Roy, Madhuparna; Pandey, Pradeep; Kumar, Shailendra; Parihar, P. S.

2017-12-01

A concrete study combining optical microscopy, Raman spectroscopy and X-ray diffractometry, was carried out on subsurface samples of basement granite and melt breccia from Mohar (Dhala) impact structure, Shivpuri district, Madhya Pradesh, India. Optical microscopy reveals aberrations in the optical properties of quartz and feldspar in the form of planar deformation feature-like structures, lowered birefringence and mosaics in quartz, toasting, planar fractures and ladder texture in alkali feldspar and near-isotropism in bytownite. It also brings to light incidence of parisite, a radioactive rare mineral in shocked granite. Raman spectral pattern, peak positions, peak widths and multiplicity of peak groups of all minerals, suggest subtle structural/crystallographic deviations. XRD data further reveals minute deviations of unit cell parameters of quartz, alkali feldspar and plagioclase, with respect to standard α-quartz, high- and low albite and microcline. Reduced cell volumes in these minerals indicate compression due to pressure. The c0/a0 values indicate an inter-tetrahedral angle roughly between 120o and 144o, further pointing to a possible pressure maxima of around 12 GPa. The observed unit cell aberration of minerals may indicate an intermediate stage between crystalline and amorphous stages, thereby, signifying possible overprinting of decompression signatures over shock compression effects, from a shock recovery process.

Nanoscale quantification of intracellular element concentration by X-ray fluorescence microscopy combined with X-ray phase contrast nanotomography

NASA Astrophysics Data System (ADS)

Gramaccioni, Chiara; Yang, Yang; Procopio, Alessandra; Pacureanu, Alexandra; Bohic, Sylvain; Malucelli, Emil; Iotti, Stefano; Farruggia, Giovanna; Bukreeva, Inna; Notargiacomo, Andrea; Fratini, Michela; Valenti, Piera; Rosa, Luigi; Berlutti, Francesca; Cloetens, Peter; Lagomarsino, Stefano

2018-01-01

We present here a correlative X-ray microscopy approach for quantitative single cell imaging of molar concentrations. By combining the elemental content provided by X-ray fluorescence microscopy and the morphology information extracted from X-ray phase nanotomography, we determine the intracellular molarity distributions. This correlative method was demonstrated on a freeze-dried human phagocytic cell to obtain the absolute elemental concentration maps of K, P, and Fe. The cell morphology results showed a very good agreement with atomic-force microscopy measurements. This work opens the way for non-destructive single cell chemical analysis down to the sub-cellular level using exclusively synchrotron radiation techniques. It will be of high interest in the case where it is difficult to access the morphology using atomic-force microscopy, for example, on frozen-hydrated cells or tissues.

High-speed X-ray microscopy by use of high-resolution zone plates and synchrotron radiation.

PubMed

Hou, Qiyue; Wang, Zhili; Gao, Kun; Pan, Zhiyun; Wang, Dajiang; Ge, Xin; Zhang, Kai; Hong, Youli; Zhu, Peiping; Wu, Ziyu

2012-09-01

X-ray microscopy based on synchrotron radiation has become a fundamental tool in biology and life sciences to visualize the morphology of a specimen. These studies have particular requirements in terms of radiation damage and the image exposure time, which directly determines the total acquisition speed. To monitor and improve these key parameters, we present a novel X-ray microscopy method using a high-resolution zone plate as the objective and the matching condenser. Numerical simulations based on the scalar wave field theory validate the feasibility of the method and also indicate the performance of X-ray microscopy is optimized most with sub-10-nm-resolution zone plates. The proposed method is compatible with conventional X-ray microscopy techniques, such as computed tomography, and will find wide applications in time-resolved and/or dose-sensitive studies such as living cell imaging.

X-ray reciprocal space mapping of dislocation-mediated strain relaxation during InGaAs/GaAs(001) epitaxial growth

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

Sasaki, Takuo; Ohshita, Yoshio; Kamiya, Itaru

2011-12-01

Dislocation-mediated strain relaxation during lattice-mismatched InGaAs/GaAs(001) heteroepitaxy was studied through in situ x-ray reciprocal space mapping (in situ RSM). At the synchrotron radiation facility SPring-8, a hybrid system of molecular beam epitaxy and x-ray diffractometry with a two-dimensional detector enabled us to perform in situ RSM at high-speed and high-resolution. Using this experimental setup, four results in terms of film properties were simultaneously extracted as functions of film thickness. These were the lattice constants, the diffraction broadenings along in-plane and out-of-plane directions, and the diffuse scattering. Based on correlations among these results, the strain relaxation processes were classified into fourmore » thickness ranges with different dislocation behavior. In addition, the existence of transition regimes between the thickness ranges was identified. Finally, the dominant dislocation behavior corresponding to each of the four thickness ranges and transition regimes was noted.« less

Fluorescence properties of alloyed ZnSeS quantum dots overcoated with ZnTe and ZnTe/ZnS shells

NASA Astrophysics Data System (ADS)

Adegoke, Oluwasesan; Mashazi, Philani; Nyokong, Tebello; Forbes, Patricia B. C.

2016-04-01

Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.

Synthesis of LiFePO4/C composites based on natural iron stone using a sol gel method

NASA Astrophysics Data System (ADS)

Angela, Riyan; Islam, Humaatul; Sari, Vamellia; Latif, Chaironi; Zainuri, Mochamad; Pratapa, Suminar

2017-01-01

Synthesis of LiFePO4/C composites has been carried out using a sol gel method. The Fe precursor was made from a natural iron stone of Tanah Laut, South Kalimantan, while the other raw materials were commercial Li2CO3 powder and NH4H2PO4 powder with HCl and water as solvents. Citric acid was used as the carbon source in the synthesis. This study used a molar ratio of 1:1:2 for Li:Fe:P with variation of added citric acid of 1.5 and 2.5 g. The solutions were dried in air at 100°C. The dried powders were characterized using DSC-TGA and then calcined at 600 and 700°C under argon environment for 10 hours. The calcined powders were characterized by X-ray diffractometry (XRD), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), and LCR meter. It was found that the samples contained LiFePO4 as the dominant phase and LiFeP2O7 and Fe2O3 as secondary phases. The analysis showed that the addition of citric acid influenced the electronic conductivity of the composites. A Rietveld relative weight fraction of up to 94.7% was achieved in the synthesis at temperature 600°C. The LFP/C sample exhibited electronic conductivity of 4.56×10-3 Scm-1 which was six times of that of the pure LFP.

SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

NASA Astrophysics Data System (ADS)

Chanadee, Tawat

2017-11-01

Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

Fluorine incorporation into SnO2 nanoparticles by co-milling with polyvinylidene fluoride

NASA Astrophysics Data System (ADS)

Senna, Mamoru; Turianicová, Erika; Šepelák, Vladimír; Bruns, Michael; Scholz, Gudrun; Lebedkin, Sergei; Kübel, Christian; Wang, Di; Kaňuchová, Mária; Kaus, Maximilian; Hahn, Horst

2014-04-01

Fluorine was incorporated into SnO2 nanoparticles from polyvinylidene fluoride (PVdF) by co-milling. The incorporation process was triggered by an oxidative partial decomposition of PVdF due to the abstraction of oxygen atoms, and began soon after milling with a simultaneous decrease in the crystallite size of SnO2 from 56 nm to 19 nm, and increase in the lattice strain by a factor 7. Appearance of D and G Raman peaks indicated that the decomposition of PVdF was accompanied by the formation of nanometric carbon species. Decomposing processes of PVdF were accompanied by the continuous change in the states of F, with a decrease of C-F in PVdF and increase in Sn-F. This indicates the gradual incorporation of F into SnO2, by replacing a part of oxygen in the oxide with fluorine. These serial mechanochemical reaction processes were discussed on the basis of X-ray diffractometry, FT-IR, Raman and UV-Vis diffuse reflectance spectroscopy, transmission electron microscopy, F1s, Sn3d and C1s X-ray photoelectron spectroscopy and Auger electron spectra, as well as magic angle spinning NMR spectroscopy of 19F and 119Sn. The present findings serve as an initial stage of incorporating fluorine into SnO2 via a solvent-free solid-state process, toward the rational fabrication of fluorine doped SnO2 powders.

Growth and Characteristic of Amorphous Nano-Granular TeO2-V2O5-NiO Thin Films

NASA Astrophysics Data System (ADS)

Hosseinzadeh, Sh.; Rahmati, A.; Bidadi, H.

2016-12-01

TeO2-V2O5-NiO thin films were deposited using thermal evaporation from 40TeO2-(60-y)V2O5-yNiO (y=0-30mol%) target. Structural analysis of the films was identified by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The amorphous TeO2-V2O5-NiO films have nanosized clear grain structure and sharp grain boundaries. DC conductivity and current-voltage (I-V) characteristic of TeO2-V2O5-NiO thin films were measured in the temperature range of 300-423K. As nickel oxide (NiO) content increases, the DC conductivity decreases up to two orders in value (10-9-10-11Sṡcm-1). Temperature dependence of conductivity is described using the small polaron hopping (SPH) model as well. Poole-Frenkel effect is observed at high external electric field. The optical absorption spectra of the TeO2-V2O5-NiO thin films were recorded in the wavelength range of 380-1100nm. The absorption coefficient revealed bandgap shrinkage (3.01-2.3eV) and band tail widening, due to an increase in NiO content. Energy dispersive X-ray spectroscopy (EDX) was used to determine elemental composition. In TeO2-V2O5-NiO thin films, the NiO content is around fifth of the initial target.

Surface engineering of nanoparticles with macromolecules for epoxy curing: Development of super-reactive nitrogen-rich nanosilica through surface chemistry manipulation

NASA Astrophysics Data System (ADS)

Jouyandeh, Maryam; Jazani, Omid Moini; Navarchian, Amir H.; Shabanian, Meisam; Vahabi, Henri; Saeb, Mohammad Reza

2018-07-01

Curing behavior of epoxy-based nanocomposites depends on dispersion state of nanofillers and their physical and chemical interactions with the curing moieties. In this work, a systematic approach was introduced for chemical functionalization of nanoparticles with macromolecules in order to enrich crosslinking potential of epoxy/amine systems, particularly at late stages of cure where the curing is diffusion-controlled. Super-reactive hyperbranched polyethylenimine (PEI)-attached nanosilica was materialized in this work to facilitate epoxy-amine curing. Starting from coupling [3-(2,3-epoxypropoxy) propyl] trimethoxysilane (EPPTMS) with hyperbranched PEI, a super-reactive macromolecule was obtained and subsequently grafted onto the nanosilica surface. Eventually, a thermally-stable highly-curable nanocomposite was attained by replacement of amine and imine groups of the PEI with imide and amide groups through the reaction with pyromellitic acid dianhydride. Fourier-transform infrared spectrophotometry, X-ray diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy approved successful grafting of polymer chains onto the nanosilica surface. Thermogravimetric analyses approved a relatively high grafting ratio of ca. 21%. Curing potential of the developed super-reactive nanoparticle was uncovered through nonisothermal differential scanning calorimetry signifying an enthalpy rise of ca. 120 J/g by addition of 2 wt.% to epoxy at 5 °C/min heating rate. Even at low concentration of 0.5 wt.%, the glass transition temperature of epoxy increased from 128 to 156 °C, demonstrating prolonged crosslinking.

A novel analytical method for pharmaceutical polymorphs by terahertz spectroscopy and the optimization of crystal form at the discovery stage.

PubMed

Ikeda, Yukihiro; Ishihara, Yoko; Moriwaki, Toshiya; Kato, Eiji; Terada, Katsuhide

2010-01-01

A novel analytical method for the determination of pharmaceutical polymorphs was developed using terahertz spectroscopy. It was found out that each polymorph of a substance showed a specific terahertz absorption spectrum. In particular, analysis of the second derivative spectrum was enormously beneficial in the discrimination of closely related polymorphs that were difficult to discern by powder X-ray diffractometry. Crystal forms that were obtained by crystallization from various solvents and stored under various conditions were specifically characterized by the second derivative of each terahertz spectrum. Fractional polymorphic transformation for substances stored under stressed conditions was also identified by terahertz spectroscopy during solid-state stability test, but could not be detected by powder X-ray diffractometry. Since polymorphs could be characterized clearly by terahertz spectroscopy, further physicochemical studies could be conducted in a timely manner. The development form of compound examined was determined by the results of comprehensive physicochemical studies that included thermodynamic relationships, as well as chemical and physicochemical stability. In conclusion, terahertz spectroscopy, which has unique power in the elucidation of molecular interaction within a crystal lattice, can play more important role in physicochemical research. Terahertz spectroscopy has a great potential as a tool for polymorphic determination, particularly since the second derivative of the terahertz spectrum possesses high sensitivity for pharmaceutical polymorphs.

Quantitative determination of airborne respirable non-fibrous alpha-silicon carbide by x-ray powder diffractometry.

PubMed

Bye, E; Føreland, S; Lundgren, L; Kruse, K; Rønning, R

2009-06-01

The purpose of the present investigation was to establish a method for the determination of airborne respirable non-fibrous silicon carbide (SiC). The main application is within the industrial production of SiC. Due to the complex airborne aerosol mixture of crystalline compounds in the SiC industry, X-ray powder diffractometry was selected as the most appropriate method. Without any international standard material for the respirable fraction of non-fibrous SiC, pure and suitable products from three SiC plants in Norway were selected. These products have a median particle diameter in the range 4.4-5.1 mum. The method is based on thin sample technique, with the dust deposited on a polycarbonate filter. Absorption correction is done by standard procedures with the use of a silver filter, situated below the polycarbonate filter. The diffraction line used for quantitative determination was selected carefully. This was done to avoid interferences from quartz, cristobalite, and graphite, which all are airborne components present in the atmosphere during the industrial process. The instrumental limit of detection for the method is 12 microg. This method has been used to determine airborne non-fibrous SiC in a comprehensive ongoing project in the Norwegian SiC industry for further epidemiological studies. The method is fully applicable for compliance work.

PtyNAMi: ptychographic nano-analytical microscope at PETRA III: interferometrically tracking positions for 3D x-ray scanning microscopy using a ball-lens retroreflector

NASA Astrophysics Data System (ADS)

Schroer, Christian G.; Seyrich, Martin; Kahnt, Maik; Botta, Stephan; Döhrmann, Ralph; Falkenberg, Gerald; Garrevoet, Jan; Lyubomirskiy, Mikhail; Scholz, Maria; Schropp, Andreas; Wittwer, Felix

2017-09-01

In recent years, ptychography has revolutionized x-ray microscopy in that it is able to overcome the diffraction limit of x-ray optics, pushing the spatial resolution limit down to a few nanometers. However, due to the weak interaction of x rays with matter, the detection of small features inside a sample requires a high coherent fluence on the sample, a high degree of mechanical stability, and a low background signal from the x-ray microscope. The x-ray scanning microscope PtyNAMi at PETRA III is designed for high-spatial-resolution 3D imaging with high sensitivity. The design concept is presented with a special focus on real-time metrology of the sample position during tomographic scanning microscopy.

Triaxial Measurement Method for Analysis of Residual Stress after High Feed Milling by X-Ray Diffraction

NASA Astrophysics Data System (ADS)

Čuma, Matúš; Török, Jozef; Telišková, Monika

2016-12-01

Surface integrity is a broad term which includes various quality factors affecting the functional properties of parts. Residual stress is one of these factors. Machining generates residual stresses in the surface and subsurface layers of the structural elements. X-ray diffractometry is a non-destructive method applicable for the measurement of residual stresses in surface and subsurface layers of components. The article is focused on the non-destructive progressive method of triaxial measurement of residual stress after machining the surface of sample by high feed milling technology. Significance of triaxial measuring is the capability of measuring in different angles so it is possible to acquire stress tensor containing normal and shear stress components acting in the spot of measuring, using a Cartesian coordinate system.

Symposium LL: Nanowires--Synthesis Properties Assembly and Application

DTIC Science & Technology

2010-09-10

dedicated hard x - ray microscopy beamline is operated in partnership with the Advanced Photon Source to provide fluorescence, diffraction, and...characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X - ray diffraction (XRD) measurements, proving it to be...Investigation of Preferred Growth Direction of GaN Nanorods by Synchrotron X - ray Reciprocal Space Mapping. Yuri Sohn1, Sanghwa Lee1, Chinkyo Kim1 and Dong

Development of Thin Films as Potential Structural Cathodes to Enable Multifunctional Energy-Storage Structural Composite Batteries for the U.S. Army’s Future Force

DTIC Science & Technology

2011-09-01

glancing angle X - ray diffraction (GAXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrochemical...Emission SEM FWHM full width at half maximum GAXRD glancing angle X - ray diffraction H3COCH2CH2OH 2-methoxyethanol LiMn2O4 lithium manganese oxide...were characterized by scanning electron microscopy (SEM), X - ray diffraction (XRD), and atomic force microscopy (AFM). In addition,

Study the effect of mechanical alloying parameters on synthesis of Cr{sub 2}Nb–Al{sub 2}O{sub 3} nanocomposite

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

Shayesteh, Payam, E-mail: shayesteh.payam@gmail.com; Mirdamadi, Shamseddin; Razavi, Hossein

2014-01-01

Graphical abstract: - Highlights: • Cr{sub 2}Nb–Al{sub 2}O{sub 3} nanocomposite synthesized through MA. • Effect of BPR, rotating speed, milling time and PCA concentration investigated. • After annealing at 1100 °C crystalline phase were appeared. • Williamson–Hall analysis was used in order to study the grain size of nano composite. - Abstract: In this study, Cr{sub 2}Nb–20 vol.% Al{sub 2}O{sub 3} nanocomposite was prepared successfully by mechanochemical reaction between Al, Nb and Cr{sub 2}O{sub 3} powders. Amorphization of powder occurred during mechanical alloying because of high energy collisions between powders and steel balls in milling container which transfer high degreemore » of energy to powders. Therefore, annealing was needed to form crystalline phases. The influence of different mechanical alloying parameters such as BPR, rotating speed, milling time and PCA concentration on synthesis of composite material were investigated. After mechanical alloying, the powder was encapsulated in quartz and then annealed at 1100 °C for 3 h. After annealing, 3 different phases were appeared (Cr{sub 2}Nb (cubic), Cr{sub 2}Nb (hexagonal) and α-Al{sub 2}O{sub 3}). The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM)« less

Solid-state characterization of mefenamic acid.

PubMed

Panchagnula, Ramesh; Sundaramurthy, Prakash; Pillai, Omathanu; Agrawal, Shrutidevi; Raj, Yasvanth Ashok

2004-04-01

The purpose of this study was to characterize mefenamic acid (MA) from commercial samples and samples crystallized from different solvents. Various techniques used for characterization included microscopy (hot stage microscopy, scanning electron microscopy), intrinsic dissolution rate, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffractometry (pXRD). The commercial samples varied in their crystal habit, thermal behavior, and intrinsic dissolution rate. It was found that the commercial samples were polymorphic Form I, which converted to Form II on heating in a DSC pan. Similarly, compression in an intrinsic dissolution rate (IDR) press resulted in the conversion of Form I to Form II. On the other hand, the samples recrystallized from different solvents under varying conditions yielded different crystal habits. Stirring and degree of supersaturation significantly influenced the crystal habit in all the solvents used in the study. Samples crystallized from ethanol and tetrahydrofuran yielded Form I, which behaved similarly to the commercial samples (M1 and M3). Recrystallization from ethyl acetate at a fast cooling rate yielded Form I, which on melting crystallized to Form II. The form I crystallized from ethyl acetate by fast cooling converted partially to form II on storing at ambient conditions. Forms I and II of MA were enantiotropically related. The results demonstrate the variable material characteristics of the commercial samples of MA and the influence of the crystallizing conditions on the formation of the polymorphs. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association.

Electrochemical properties of monolithic nickel sulfide electrodes for use in sodium batteries

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

Go, Dae-Yeon; Park, Jinsoo, E-mail: jsp@ikw.ac.kr; Noh, Pan-Jin

2014-10-15

Highlights: • We succeeded in preparing monolithic Ni{sub 3}S{sub 2} integrated electrode through the sulfuration. • The sulfuration is a facile and useful method to synthesize metal sulfides with nanostructure. • As-prepared monolithic Ni{sub 3}S{sub 2} electrodes showed very stable and cycle performance over charge/discharge cycling. - Abstract: Monolithic nickel sulfide electrodes were prepared using a facile synthesis method, sulfuration and annealing. As-prepared Ni{sub 3}S{sub 2} electrodes were characterized by X-ray diffractometry and field emission scanning electron microscopy. Thermal stability was determined by thermal gravimetric analysis and differential scanning calorimetry. Electrochemical properties were measured by galvanostatic charge and discharge cyclingmore » for Na-ion batteries. Three kinds of Ni{sub 3}S{sub 2} electrodes were prepared by varying the sulfuration time (5, 15 and 25 min). The electrochemical results indicated that the capacities increased with an increase in sulfuration time and the cycle performance was stable as a result of monolithic integration of nanostructured Ni{sub 3}S{sub 2} on Ni plates, leading to low interfacial resistance.« less

Preparation and physical properties of tara gum film reinforced with cellulose nanocrystals.

PubMed

Ma, Qianyun; Hu, Dongying; Wang, Lijuan

2016-05-01

Cellulose nanocrystals (CNC) prepared from microcrystalline cellulose were blended in tara gum solution to prepare nanocomposite films. The morphology, crystallinity, and thermal properties of the CNC and films were evaluated by using transmission electron microscopy, X-ray diffractometry, and thermogravimetric analysis, respectively. The resultant CNC was rod-shaped with diameters of around 8.6 nm. The effect of CNC content on physical and thermal properties of films was studied. The composite film tensile strength increased from 27.86 to 65.73 MPa, elastic modulus increased from 160.98 MPa to 882.49 MPa and the contact angle increased from 55.8° to 98.7° with increasing CNC content from 0 to 6 wt%. However, CNC addition increased the thermal stability slightly and CNC content above 6 wt% decreased the tensile strength by CNC aggregation in the matrix. The nanocomposite film containing 6 wt% CNC possessed the highest light transmittance, mechanical properties, and lowest oxygen permeability. CNC addition is a suitable method to modify tara gum matrix polymer properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of Copper-Antimony-Sulfide Nanocrystals for Solution-Processed Solar Cells.

PubMed

Suehiro, Satoshi; Horita, Keisuke; Yuasa, Masayoshi; Tanaka, Tooru; Fujita, Katsuhiko; Ishiwata, Yoichi; Shimanoe, Kengo; Kida, Tetsuya

2015-08-17

The p-type nanocrystals (NCs) of copper-based chalcogenides, such as CuInSe2 and Cu2ZnSnS4, have attracted increasing attention in photovoltaic applications due to their potential to produce cheap solution-processed solar cells. Herein, we report the synthesis of copper-antimony-sulfide (CAS) NCs with different crystal phases including CuSbS2, Cu3SbS4, and Cu12Sb4S13. In addition, their morphology, crystal phase, and optical properties were characterized using transmission electron microscopy, X-ray diffractometry, UV-vis-near-IR spectroscopy, and photoemission yield spectroscopy. The morphology, crystal phase, and electronic structure were significantly dependent on the chemical composition in the CAS system. Devices were fabricated using particulate films consisting of CAS NCs prepared by spin coating without a high-temperature treatment. The CAS NC-based devices exhibited a diode-like current-voltage characteristic when coupled with an n-type CdS layer. In particular, the CuSbS2 NC devices exhibited photovoltaic responses under simulated sunlight, demonstrating its applicability for use in solution-processed solar cells.

Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas.

PubMed

Tanaka, Manabu; Kageyama, Takuya; Sone, Hirotaka; Yoshida, Shuhei; Okamoto, Daisuke; Watanabe, Takayuki

2016-04-06

Lithium metal oxide nanoparticles were synthesized by induction thermal plasma. Four different systems-Li-Mn, Li-Cr, Li-Co, and Li-Ni-were compared to understand formation mechanism of Li-Me oxide nanoparticles in thermal plasma process. Analyses of X-ray diffractometry and electron microscopy showed that Li-Me oxide nanoparticles were successfully synthesized in Li-Mn, Li-Cr, and Li-Co systems. Spinel structured LiMn₂O₄ with truncated octahedral shape was formed. Layer structured LiCrO₂ or LiCoO₂ nanoparticles with polyhedral shapes were also synthesized in Li-Cr or Li-Co systems. By contrast, Li-Ni oxide nanoparticles were not synthesized in the Li-Ni system. Nucleation temperatures of each metal in the considered system were evaluated. The relationship between the nucleation temperature and melting and boiling points suggests that the melting points of metal oxides have a strong influence on the formation of lithium metal oxide nanoparticles. A lower melting temperature leads to a longer reaction time, resulting in a higher fraction of the lithium metal oxide nanoparticles in the prepared nanoparticles.

Interaction of pulsed laser radiation with a powder complex based on the Al-Mg-C matrix

NASA Astrophysics Data System (ADS)

Voznesenskaya, A.; Khorkov, K.; Kochuev, D.; Zhdanov, A.; Morozov, V.

2018-01-01

Experimental work on laser melting of the Al powder composition has been carried out. The influence of the duration of the laser pulse on the result of processing the powder composition has been studied. In this work, the powder material was obtained by the joint mechanical activation of matrix material and filler particles in high-energy ball mills. The research work consisted of analyzing the starting material, the phase composition, the particle size distribution, and the morphology of the powder particles. The obtained samples also studied the phase composition, the presence of pores, cracks, the surface of the formed coating, the average height of the roller. The obtained samples were studied by X-ray diffractometry, Raman spectroscopy, and microsections of the structures obtained by optical microscopy. On the basis of the data obtained, conclusions were drawn about changes in the structural-phase composition, the nature of the distribution, the localization of alloying additives in the course of phase-to-phase transitions, and the change in the phase states of alloying additives.

Characterization and electrochemical properties of Ni(Si)/Ni5Si2 multiphase coatings prepared by HVOF spraying

NASA Astrophysics Data System (ADS)

Verdian, M. M.; Raeissi, K.; Salehi, M.

2012-11-01

Ni(Si)/Ni5Si2 powders were produced by mechanical alloying (MA) of Ni-25 at.% Si powder mixture. Then, the as-milled powders were sprayed onto copper substrate using high velocity oxy-fuel (HVOF) process. The phase composition and microstructure of the coatings were examined by X-ray diffractometry and scanning electron microscopy. Polarization tests and electrochemical impedance spectroscopy (EIS) measurements were also employed to study corrosion performance of the coatings in 3.5% NaCl solution. The results showed that although single phase Ni3Si was formed during annealing of Ni(Si)/Ni5Si2 powders, but, only Ni(Si) and Ni5Si2 are present in HVOF coatings and no new phase has been formed during spraying. The coatings had microhardness up to 746 HV0.05. Further investigations showed the corrosion performance of multiphase coatings in 3.5% NaCl solution was better than that of copper substrate. The phase transitions during MA, HVOF and annealing processes were discussed in association with Ni-Si phase diagram and nature of each process.

Novel Solid Encapsulation of Ethylene Gas Using Amorphous α-Cyclodextrin and the Release Characteristics.

PubMed

Ho, Binh T; Bhandari, Bhesh R

2016-05-04

This research investigated the encapsulation of ethylene gas into amorphous α-cyclodextrins (α-CDs) at low (LM) and high (HM) moisture contents at 1.0-1.5 MPa for 24-120 h and its controlled release characteristics at 11.2-52.9% relative humidity (RH) for 1-168 h. The inclusion complexes (ICs) were characterized using X-ray diffractometry (XRD), nuclear magnetic resonance spectroscopy (CP-MAS (13)C NMR), and scanning electron microscopy (SEM). Ethylene concentrations in the ICs were from 0.45 to 0.87 mol of ethylene/mol CD and from 0.42 to 0.54 mol of ethylene/mol CD for LM and HM α-CDs, respectively. Ethylene gas released from the encapsulated powder at higher rates with increasing RH. An analysis of release kinetics using Avrami's equation showed that the LM and HM amorphous α-CDs were not associated with significant differences in release constant k and parameter n for any given RH condition. NMR spectra showed the presence of the characteristic carbon-carbon double bond of ethylene gas in the encapsulated α-CD powder.

Photocatalytic degradation of an azo textile dye (C.I. Reactive Red 195 (3BF)) in aqueous solution over copper cobaltite nanocomposite coated on glass by Doctor Blade method

NASA Astrophysics Data System (ADS)

Habibi, Mohammad Hossein; Rezvani, Zoya

2015-08-01

The degradation of C.I. Reactive Red 195 (3BF) in aqueous solution using copper cobaltite nanocomposite coated on glass by Doctor Blade method was studied. Structural, optical and morphological properties of nanocomposite coatings were characterized by X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and field emission scanning electron microscopy (FESEM). The nanoparticles exhibit a particle size of 31 nm, showing a good nanoscale crystalline morphology. The photocatalytic activity of copper cobaltite nanocomposite coated on glass was studied by performing the photocatalytic degradation of 3BF at different irradiation time. The effect of irradiation time on the degradation of 3BF was studied and the results showed that more than 85% of the 3BF was degraded in 45 min of irradiation. The pseudo-first-order kinetic models were used and the rate constants were evaluated with pseudo first order rate constants of 4.10 × 10-2 min-1. The main advantage of the photocatalyst coated on glass overcomes the difficulties in separation and recycle of photocatalyst suspensions.

Coherent x-ray zoom condenser lens for diffractive and scanning microscopy.

PubMed

Kimura, Takashi; Matsuyama, Satoshi; Yamauchi, Kazuto; Nishino, Yoshinori

2013-04-22

We propose a coherent x-ray zoom condenser lens composed of two-stage deformable Kirkpatrick-Baez mirrors. The lens delivers coherent x-rays with a controllable beam size, from one micrometer to a few tens of nanometers, at a fixed focal position. The lens is suitable for diffractive and scanning microscopy. We also propose non-scanning coherent diffraction microscopy for extended objects by using an apodized focused beam produced by the lens with a spatial filter. The proposed apodized-illumination method will be useful in highly efficient imaging with ultimate storage ring sources, and will also open the way to single-shot coherent diffraction microscopy of extended objects with x-ray free-electron lasers.

X-ray microscopy with high-resolution zone plates: recent developments

NASA Astrophysics Data System (ADS)

Schneider, Gerd; Wilhein, Thomas; Niemann, Bastian; Guttman, P.; Schliebe, T.; Lehr, J.; Aschoff, H.; Thieme, Juergen; Rudolph, Dietbert M.; Schmahl, Guenther A.

1995-09-01

In order to expand the applications of x-ray microscopy, developments in the fields of zone plate technology, specimen preparation and imaging techniques have been made. A new cross- linked polymer chain electron beam resist allows us to record zone plate pattern down to 19 nm outermost zone width. High resolution zone plates in germanium with outermost zone widths down to 19 nm have been developed. In addition, phase zone plates in nickel down to 30 nm zone width have been made by electroplating. In order to enhance the image contrast for weak absorbing objects, the phase contrast method for x-ray microscopy was developed and implemented on the Gottingen x-ray microscope at BESSY. The effects of x ray absorption on the structure of biological specimen limits the maximum applicable radiation dose and therefore the achievable signal to noise ratio for an artifact-free x-ray image. To improve the stability especially of biological specimen, a cryogenic object chamber has been developed and tested. It turns out that at the operating temperature T less than or equal to 130 K unfixed biological specimen can be exposed to a radiation dose of 109 - 1010 Gy without any observable structural changes. A multiple-angle viewing stage allows us to take stereoscopic images with the x-ray microscope, giving a 3D-impression of the object. As an example for the applications of x-ray microscopy in biology, erythrocytes infected by malaria parasite have been examined. Studies of the aggregation of hematite by sodium sulfate gives an example for the application of x-ray microscopy in the field of colloid research.

Ultrafast Science Opportunities with Electron Microscopy

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

Durr, Hermann

X-rays and electrons are two of the most fundamental probes of matter. When the Linac Coherent Light Source (LCLS), the world’s first x-ray free electron laser, began operation in 2009, it transformed ultrafast science with the ability to generate laser-like x-ray pulses from the manipulation of relativistic electron beams. This document describes a similar future transformation. In Transmission Electron Microscopy, ultrafast relativistic (MeV energy) electron pulses can achieve unsurpassed spatial and temporal resolution. Ultrafast temporal resolution will be the next frontier in electron microscopy and can ideally complement ultrafast x-ray science done with free electron lasers. This document describes themore » Grand Challenge science opportunities in chemistry, material science, physics and biology that arise from an MeV ultrafast electron diffraction & microscopy facility, especially when coupled with linac-based intense THz and X-ray pump capabilities.« less

Molecular beam epitaxial growth and structural characterization of ZnS on (001) GaAs

NASA Technical Reports Server (NTRS)

Benz, R. G., II; Huang, P. C.; Stock, S. R.; Summers, C. J.

1988-01-01

The effect of surface nucleation processes on the quality of ZnS layers grown on (001) GaAs substrates by molecular beam epitaxy is reported. Reflection high energy electron diffraction indicated that nucleation at high temperatures produced more planar surfaces than nucleation at low temperatures, but the crystalline quality as assessed by X-ray double crystal diffractometry is relatively independent of nucleation temperature. A critical factor in layer quality was the initial roughness of the GaAs surfaces.

Transmission X-ray microscopy for full-field nano-imaging of biomaterials

PubMed Central

ANDREWS, JOY C; MEIRER, FLORIAN; LIU, YIJIN; MESTER, ZOLTAN; PIANETTA, PIERO

2010-01-01

Imaging of cellular structure and extended tissue in biological materials requires nanometer resolution and good sample penetration, which can be provided by current full-field transmission X-ray microscopic techniques in the soft and hard X-ray regions. The various capabilities of full-field transmission X-ray microscopy (TXM) include 3D tomography, Zernike phase contrast, quantification of absorption, and chemical identification via X-ray fluorescence and X-ray absorption near edge structure (XANES) imaging. These techniques are discussed and compared in light of results from imaging of biological materials including microorganisms, bone and mineralized tissue and plants, with a focus on hard X-ray TXM at ≤ 40 nm resolution. PMID:20734414

Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO2.

PubMed

Ozmen, Murat; Güngördü, Abbas; Erdemoglu, Sema; Ozmen, Nesrin; Asilturk, Meltem

2015-08-01

The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO2. Undoped and Mn-doped TiO2 nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO2 was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO2 nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO2 increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2-4h of degradation. However, biochemical assays showed that both Mn-doped TiO2 and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn-doped TiO2 should be considered due to nanomaterial applications and for spilled nanoparticles in an aquatic ecosystem. Also, the risk of nanoparticles should be considered using indicator reference biochemical markers to verify the environmental health impacts. Copyright © 2015 Elsevier B.V. All rights reserved.

Relationship between crystal structure and solid-state properties of pharmaceuticals

NASA Astrophysics Data System (ADS)

Sheth, Agam R.

This thesis strives to understand the structure-property relationships of some pharmaceutical crystals at the molecular level with emphasis on the effect of secondary processing on the solid phase. Using single crystal X-ray diffractometry (SCXRD), the structure of warfarin sodium 2-propanol adduct (W) was established to be a true solvate, contrary to previous reports. Using dynamic water vapor sorption, optical and environmental scanning electron microscopy, SCXRD, powder X-ray diffractometry (PXRD), volume computations and molecular modeling, the effect of relative humidity and temperature on the crystal structure of W was investigated. Ab initio calculations on piroxicam showed that the difference in energy between the two polymorphs, I and II, arises predominantly from the difference between their lattice energies. The detailed hydrogen bonding networks of the two polymorphs are described and compared using graph sets. Despite stabilization of the polymorphs by hydrogen bonds, pair-wise distribution function transforms show a loss of polymorphic memory upon cryogrinding the two polymorphs, leading to a difference in recrystallization behavior between amorphous piroxicam prepared from polymorphs I and II. Structural and solid-state changes of piroxicam polymorphs under mechanical stress were investigated using cryogenic grinding, PXRD, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, and diffuse-reflectance solid-state Fourier-transform infrared spectroscopy. Intermolecular proton transfer was found to accompany changes in phase and color observed upon cryogrinding the two polymorphs. Model-free and model-fitting studies of the dehydration kinetics of piroxicam monohydrate (PM) showed the dependence of activation energy ( Ea) on both isothermal and non-isothermal heating conditions, and on the fraction of conversion. In the constant-E a region, isothermal dehydration follows the two-dimensional phase boundary model, while non-isothermal dehydration follows a mechanism intermediate between two- and three-dimensional diffusion that cannot be described by any of the common models. Structural studies suggest that the complex hydrogen bond pattern in PM is responsible for the observed dehydration behavior. Ab initio calculations provide an explanation for the changes in the molecular and crystal structures accompanying the reversible change in hydration state between anhydrous piroxicam Form I and PM. The thesis further demonstrates the utility of model-free analysis in describing complex dehydration kinetics.

Thermal behavior of potato starch and water-vaporization behavior of its paste controlled with amino acid and peptide-rich food materials.

PubMed

Sakauchi, Satoshi; Hattori, Makoto; Yoshida, Tadashi; Yagishita, Takahiro; Ito, Koichi; Akemitsu, Shin-Ichi; Takahashi, Koji

2010-03-01

The particular effect of 4 kinds of amino acid and peptide-rich food material (APRM) containing different charged amino acid contents on the gelatinization and retrogradation behavior of potato starch granules and on the water-vaporization behavior was analyzed by differential scanning calorimetry, rapid viscoanalysis, x-ray diffractometry, thermal gravimetry-differential thermal analysis, and pulsed NMR. APRM with a high-charged amino acid content produced unique gelatinization and retrogradation behavior in terms of an elevated gelatinization temperature, reduced viscosity, higher setback, and lower retrograded starch melting enthalpy. The recovered x-ray diffraction intensity decreased with increasing charged amino acid content. APRM with high-charged amino acid content could provide an improved paste having easy vaporization of external water in the swollen starch granules due to the reduced swelling.

Laser formation of titanium nitride films as a result of Ti coating modification in a nitrogen atmosphere

NASA Astrophysics Data System (ADS)

Eskin, Sergei

1998-12-01

Laser treatment of the 303 and 416 stainless steels with Ti precoating was studied. CW CO2 and UV ArF excimer lasers were used. The TiN films were formed at a treatment velocity of 0.5 to 3 - 5 cm/sec and a power density of CO2 laser at (3 - 5) 104 W/cm2. X-ray diffractometry, x-ray mapping and Auger electron spectroscopy techniques indicated a TiN phase on the surface with oxygen content 12 - 25 at%. The thickness of the TiN film was 0.3 - 0.4 micrometers after treatment of the 5 micrometers Ti coating and about 900 angstroms for the 0.3 micrometers coating. Some characteristics of TiN films were examined and features of the nitriding process are discussed.

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

DOE PAGES

Du, Ming; Jacobsen, Chris

2017-10-07

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

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

Du, Ming; Jacobsen, Chris

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

Hard and soft X-ray microscopy and tomography in catalysis: bridging the different time and length scales.

PubMed

Grunwaldt, Jan-Dierk; Schroer, Christian G

2010-12-01

X-ray microscopic techniques are excellent and presently emerging techniques for chemical imaging of heterogeneous catalysts. Spatially resolved studies in heterogeneous catalysis require the understanding of both the macro and the microstructure, since both have decisive influence on the final performance of the industrially applied catalysts. A particularly important aspect is the study of the catalysts during their preparation, activation and under operating conditions, where X-rays have an inherent advantage due to their good penetration length especially in the hard X-ray regime. Whereas reaction cell design for hard X-rays is straightforward, recently smart in situ cells have also been reported for the soft X-ray regime. In the first part of the tutorial review, the constraints from a catalysis view are outlined, then the scanning and full-field X-ray microscopy as well as coherent X-ray diffraction imaging techniques are described together with the challenging design of suitable environmental cells. Selected examples demonstrate the application of X-ray microscopy and tomography to monitor structural gradients in catalytic reactors and catalyst preparation with micrometre resolution but also the possibility to follow structural changes in the sub-100 nm regime. Moreover, the potential of the new synchrotron radiation sources with higher brilliance, recent milestones in focusing of hard X-rays as well as spatiotemporal studies are highlighted. The tutorial review concludes with a view on future developments in the field of X-ray microscopy that will have strong impact on the understanding of catalysts in the future and should be combined with in situ electron microscopic studies on the nanoscale and other spectroscopic studies like microRaman, microIR and microUV-vis on the macroscale.

Transmission X-ray microscopy for full-field nano imaging of biomaterials.

PubMed

Andrews, Joy C; Meirer, Florian; Liu, Yijin; Mester, Zoltan; Pianetta, Piero

2011-07-01

Imaging of cellular structure and extended tissue in biological materials requires nanometer resolution and good sample penetration, which can be provided by current full-field transmission X-ray microscopic techniques in the soft and hard X-ray regions. The various capabilities of full-field transmission X-ray microscopy (TXM) include 3D tomography, Zernike phase contrast, quantification of absorption, and chemical identification via X-ray fluorescence and X-ray absorption near edge structure imaging. These techniques are discussed and compared in light of results from the imaging of biological materials including microorganisms, bone and mineralized tissue, and plants, with a focus on hard X-ray TXM at ≤ 40-nm resolution. Copyright © 2010 Wiley-Liss, Inc.

Microwave-driven asbestos treatment and its scale-up for use after natural disasters.

PubMed

Horikoshi, Satoshi; Sumi, Takuya; Ito, Shigeyuki; Dillert, Ralf; Kashimura, Keiichiro; Yoshikawa, Noboru; Sato, Motoyasu; Shinohara, Naoki

2014-06-17

Asbestos-containing debris generated by the tsunami after the Great East Japan Earthquake of March 11, 2011, was processed by microwave heating. The analysis of the treated samples employing thermo gravimetry, differential thermal analysis, X-ray diffractometry, scanning electron microscopy, and phase-contrast microscopy revealed the rapid detoxification of the waste by conversion of the asbestos fibers to a nonfibrous glassy material. The detoxification by the microwave method occurred at a significantly lower processing temperature than the thermal methods actually established for the treatment of asbestos-containing waste. The lower treatment temperature is considered to be a consequence of the microwave penetration depth into the waste material and the increased intensity of the microwave electric field in the gaps between the asbestos fibers resulting in a rapid heating of the fibers inside the debris. A continuous treatment plant having a capacity of 2000 kg day(-1) of asbestos-containing waste was built in the area affected by the earthquake disaster. This treatment plant consists of a rotary kiln to burn the combustible waste (wood) and a microwave rotary kiln to treat asbestos-containing inorganic materials. The hot flue gas produced by the combustion of wood is introduced into the connected microwave rotary kiln to increase the energy efficiency of the combined process. Successful operation of this combined device with regard to asbestos decomposition is demonstrated.

High-throughput cocrystal slurry screening by use of in situ Raman microscopy and multi-well plate.

PubMed

Kojima, Takashi; Tsutsumi, Shunichirou; Yamamoto, Katsuhiko; Ikeda, Yukihiro; Moriwaki, Toshiya

2010-10-31

Cocrystal has attracted much attention in order to improve poor physicochemical properties, since cocrystal former crystallize with the ionic drugs as well as nonionic drugs. Cocrystal screening was usually conducted by crystallization, slurry and co-grinding techniques, however sensitivity, cost and time for screening were limited because of issues such as dissociation of cocrystal during crystallization and cost and time required for slurry and co-grinding methods. To overcome these issues, novel high-throughput cocrystal slurry screening was developed by using in situ Raman microscope and a multi-well plate. Cocrystal screening of indomethacin was conducted with 46 cocrystal formers and potential cocrystals were prepared on a large scale for the characterization with powder X-ray diffractometry, thermal analysis, and Raman microscopy and (1)H NMR spectroscopy. Compared with the characterization of scale-up cocrystals, the cocrystal screening indicated that indomethacin structured novel cocrystals with D/L-mandelic acid, nicotinamide, lactamide and benzamide which was not obtained in the screening with crystallization technique previously reported. In addition, the screening provided not only information of cocrystal formation within a day but also information of equilibrium of cocrystal formation and polymorphic transformation in one screening. Information obtained in this screening allows effective solid form selection by saving cost and time for the development. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of graphite addition into mill scale waste as a potential bipolar plates material of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Khaerudini, D. S.; Prakoso, G. B.; Insiyanda, D. R.; Widodo, H.; Destyorini, F.; Indayaningsih, N.

2018-03-01

Bipolar plates (BPP) is a vital component of proton exchange membrane fuel cells (PEMFC), which supplies fuel and oxidant to reactive sites, remove reaction products, collects produced current and provide mechanical support for the cells in the stack. This work concerns the utilization of mill scale, a by-product of iron and steel formed during the hot rolling of steel, as a potential material for use as BPP in PEMFC. On the other hand, mill scale is considered a very rich in iron source having characteristic required such as for current collector in BPP and would significantly contribute to lower the overall cost of PEMFC based fuel cell systems. In this study, the iron reach source of mill scale powder, after sieving of 150 mesh, was mechanically alloyed with the carbon source containing 5, 10, and 15 wt.% graphite using a shaker mill for 3 h. The mixed powders were then pressed at 300 MPa and sintered at 900 °C for 1 h under inert gas atmosphere. The structural changes of powder particles during mechanical alloying and after sintering were studied by X-ray diffractometry, optical microscopy, scanning electron microscopy, and microhardness measurement. The details of the presence of iron, carbon, and iron carbide (Fe-C) as the products of reactions as well as sufficient mechanical strength of the sintered materials were presented in this report.

Sonochemical synthesis of highly crystalline photocatalyst for industrial applications.

PubMed

Noman, Muhammad Tayyab; Militky, Jiri; Wiener, Jakub; Saskova, Jana; Ashraf, Muhammad Azeem; Jamshaid, Hafsa; Azeem, Musaddaq

2018-02-01

Highly photo active pure anatase form of TiO 2 nanoparticles with average particle size 4nm have been successfully synthesized by ultrasonic acoustic method (UAM). The effects of process variables i.e. precursors concentration and sonication time were investigated based on central composite design and response surface methodology. The characteristics of the resulting nanoparticles (RNP) were analyzed by scanning electron microscopy, dynamic light scattering, transmission electron microscopy, X-ray diffractometry and Raman spectroscopy. Photocatalytic experiments were performed with methylene blue dye which is considered as model organic pollutant in textile industry. A comparative analysis between the RNP and commercially available Degussa P25 for photocatalytic performance against dye removal efficiency was performed. The rapid removal of methylene blue in case of RNP indicates their higher photocatalytic activity than P25. Maximum dye removal efficiency 98.45% was achieved with optimal conditions i.e. TTIP conc. 10mL, EG conc. 4mL and sonication time 1h. Interestingly, no significant difference was found in the photocatalytic performance of RNP after calcination. Moreover, self-cleaning efficiency of RNP deposited on cotton was evaluated in RGB color space. The obtained results indicate the significant impact of ultrasonic irradiations on the photocatalytic performance of pure anatase form than any other hybrid type of TiO 2 nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroellipsometric studies of sol-gel derived Sr0.6Ba0.4Nb2O6 films

NASA Astrophysics Data System (ADS)

Ho, Melanie M. T.; Tang, T. B.; Mak, C. L.; Pang, G. K. H.; Chan, K. Y.; Wong, K. H.

2006-10-01

Sr0.6Ba0.4Nb2O6 (SBN) films have been fabricated on (001)Si substrates by a sol-gel technique. The annealing process was carried out in air at various temperatures ranging from 200to700°C. Studies using x-ray diffractometry, high resolution transmission electron microscopy, and scanning electron microscopy showed that polycrystalline films, with a grain size of about 100nm, were obtained only for annealing temperatures ⩾600°C. The optical properties of these sol-gel derived SBN films were studied by spectroscopic ellipsometry (SE). In the analysis of the measured SE spectra, a triple-layer Lorentz model has been developed and used to deduce the optical properties of the SBN films. Our systematic SE measurements revealed that the refractive indices of the SBN films increase with the annealing temperature. This increase is more pronounced at around the crystallization temperature, i.e., between 500 and 600°C. The extinction coefficients of the films also exhibit a similar trend, showing a zero value for amorphous films and larger values for films annealed at above 600°C. Our results demonstrate that while crystallization helps to raise the refractive index of the film due to film densification, it also promotes scattering by grain boundary, resulting in a larger extinction coefficient.

Concave Urinary Crystallines: Direct Evidence of Calcium Oxalate Crystals Dissolution by Citrate In Vivo

PubMed Central

Shang, Yun-Feng; Xu, Meng; Zhang, Guang-Na; Ouyang, Jian-Ming

2013-01-01

The changes in urinary crystal properties in patients with calcium oxalate (CaOx) calculi after oral administration of potassium citrate (K3cit) were investigated via atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and zeta potential analyzer. The AFM and SEM results showed that the surface of urinary crystals became concave, the edges and corners of crystals became blunt, the average size of urinary crystallines decreased significantly, and aggregation of urinary crystals was reduced. These changes were attributed to the significant increase in concentration of excreted citrate to 492 ± 118 mg/L after K3cit intake from 289 ± 83 mg/L before K3cit intake. After the amount of urinary citrate was increased, it complexed with Ca2+ ions on urinary crystals, which dissolved these crystals. Thus, the appearance of concave urinary crystals was a direct evidence of CaOx dissolution by citrate in vivo. The XRD results showed that the quantities and species of urinary crystals decreased after K3cit intake. The mechanism of inhibition of formation of CaOx stones by K3cit was possibly due to the complexation of Ca2+ with citrate, increase in urine pH, concentration of urinary inhibitor glycosaminoglycans (GAGs), and the absolute value of zeta potential after K3cit intake. PMID:24363634

Development and evaluation of paclitaxel nanoparticles using a quality-by-design approach.

PubMed

Yerlikaya, Firat; Ozgen, Aysegul; Vural, Imran; Guven, Olgun; Karaagaoglu, Ergun; Khan, Mansoor A; Capan, Yilmaz

2013-10-01

The aims of this study were to develop and characterize paclitaxel nanoparticles, to identify and control critical sources of variability in the process, and to understand the impact of formulation and process parameters on the critical quality attributes (CQAs) using a quality-by-design (QbD) approach. For this, a risk assessment study was performed with various formulation and process parameters to determine their impact on CQAs of nanoparticles, which were determined to be average particle size, zeta potential, and encapsulation efficiency. Potential risk factors were identified using an Ishikawa diagram and screened by Plackett-Burman design and finally nanoparticles were optimized using Box-Behnken design. The optimized formulation was further characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, and gas chromatography. It was observed that paclitaxel transformed from crystalline state to amorphous state while totally encapsulating into the nanoparticles. The nanoparticles were spherical, smooth, and homogenous with no dichloromethane residue. In vitro cytotoxicity test showed that the developed nanoparticles are more efficient than free paclitaxel in terms of antitumor activity (more than 25%). In conclusion, this study demonstrated that understanding formulation and process parameters with the philosophy of QbD is useful for the optimization of complex drug delivery systems. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

PubMed

Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

2017-08-01

Continuous flow experiments (450 mL min -1 ) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 5  UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

Ultrasonically-enhanced preparation, characterization of CaFe-layered double hydroxides with various interlayer halide, azide and oxo anions (CO32-, NO3-, ClO4-).

PubMed

Szabados, Márton; Varga, Gábor; Kónya, Zoltán; Kukovecz, Ákos; Carlson, Stefan; Sipos, Pál; Pálinkó, István

2018-01-01

An ultrasonically-enhanced mechanochemical method was developed to synthesize CaFe-layered double hydroxides (LDHs) with various interlayer anions (CO 3 2- , NO 3 - , ClO 4 - , N 3 - , F - , Cl - , Br - and I - ). The duration of pre-milling and ultrasonic irradiation and the variation of synthesis temperature in the wet chemical step were investigated to obtain the optimal parameters of preparation. The main method to characterize the products was X-ray diffractometry, but infrared and synchrotron-based X-ray absorption spectroscopies as well as thermogravimetric measurements were also used to learn about fine structural details. The synthesis method afforded successful intercalation of the anions, among others the azide anion, a rarely used counter ion providing a system, which enables safe handling the otherwise highly reactive anion. The X-ray absorption spectroscopic measurements revealed that the quality of the interlayered anions could modulate the spatial arrangement of the calcium ions around the iron(III) ions, but only in the second coordination sphere. Copyright © 2017 Elsevier B.V. All rights reserved.

High resolution imaging and lithography with hard x rays using parabolic compound refractive lenses

NASA Astrophysics Data System (ADS)

Schroer, C. G.; Benner, B.; Günzler, T. F.; Kuhlmann, M.; Zimprich, C.; Lengeler, B.; Rau, C.; Weitkamp, T.; Snigirev, A.; Snigireva, I.; Appenzeller, J.

2002-03-01

Parabolic compound refractive lenses are high quality optical components for hard x rays. They are particularly suited for full field imaging, with applications in microscopy and x-ray lithography. Taking advantage of the large penetration depth of hard x rays, the interior of opaque samples can be imaged with submicrometer resolution. To obtain the three-dimensional structure of a sample, microscopy is combined with tomographic techniques. In a first hard x-ray lithography experiment, parabolic compound refractive lenses have been used to project the reduced image of a lithography mask onto a resist. Future developments are discussed.

Ultrastructural imaging and molecular modeling of live bacteria using soft x-ray contact microscopy with nanoseconds laser-plasma radiation

NASA Astrophysics Data System (ADS)

Kado, Masataka; Richardson, Martin C.; Gaebel, Kai; Torres, David S.; Rajyaguru, Jayshree; Muszynski, Michael J.

1995-09-01

X-ray images of the various live bacteria, such as Staphylococcus and Streptococcus, and micromolecule such as chromosomal DNA from Escherichis coli, and Lipopolysacchride from Burkholderia cepacia, are obtained with soft x-ray contact microscopy. A compact tabletop type glass laser system is used to produce x-rays from Al, Si, and Au targets. The PMMA photoresists are used to record x-ray images. An AFM (atomic force microscope) is used to reproduce the x-ray images from the developed photoresists. The performance of the 50nm spatial resolutions are achieved and images are able to be discussed on the biological view.

Optical and low-temperature thermoelectric properties of phase-pure p-type InSe thin films

NASA Astrophysics Data System (ADS)

Urmila, K. S.; Namitha, T. A.; Philip, R. R.; Pradeep, B.

2015-08-01

Polycrystalline phase-pure p-type InSe thin films were deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 473 ± 5 K and pressure of 10-5 mbar. The as-prepared InSe thin films were analyzed by X-ray diffractometry, energy-dispersive X-ray spectroscopy, atomic force microscopy, UV-Vis-NIR spectroscopy, electrical conductivity and Hall measurements. The lattice parameters, particle size, dislocation density, number of crystallites per unit area and the lattice strain of the prepared InSe thin films were calculated and found as a = 4.00 ± 0.002 Å and c = 16.68 ± 0.002 Å, 48 ± 2 nm, 4.34 × 1010 lines cm-2, 15.37 × 1010 cm-2 and 1.8 × 10-3, respectively. The as-deposited InSe thin films showed a direct allowed transition with an optical band gap of 1.35 ± 0.02 eV and high absorption coefficient of about 105 cm-1. The oscillator energy ( E o) and dispersion energy ( E d) were calculated using the single-oscillator Wemple and DiDomenico model. The p-type conductivity and photosensitivity of the as-prepared InSe thin films confirmed their potential application in photovoltaic devices. The mean free path, relaxation time, density of states, Fermi energy and effective mass of holes in the film were determined by correlating the results of thermopower and Hall measurements. The sudden and sharp increase in thermopower from 80 to 37 K was explained as due to the effect of phonon drag on charge carriers.

[The "silica" component in the PM10 of an urban site].

PubMed

De Berardis, Barbara; Incocciati, Emma; Massera, S; Gargaro, G; Paoletti, L

2007-01-01

In vivo and in vitro toxicological studies have shown that the aged fracturated crystalline silica, which is a component of airborne particulate, exerts an important inflammatory action on airways. The evaluation of the concentration level of airborne crystalline silica in an urban area is an important research subject in order to determine the exposure levels of the general population. The aim was to study the seasonal trend of the quartz (the most common form of crystalline silica) concentration levels in the particulate inhalable faction (PM10) in the urban area of Rome. PM10, sampled by a cascade impactor, was analysed by scanning electron microscopy, equipped with a thin-window system for X-ray microanalysis (SEM/EDX) for qualitative analysis. Parallely the concentration levels of quartz in the particulate were determined by X-ray diffractometry (XRD) for quantitative analysis, using the NIOSH 7500 method (NIOSH, 1994). From September 2004 to October 2005 the abundance of silica particles, evaluated by SEM/EDX was in the range 1.6/10.4%, with a concentration level of free crystalline silica in the range 0.25/2.87 microg/mi. The equivalent diameter of silica particles ranged from 0.3 to 10.5 mircom, moreover, more than 87% of particles showed a diameter less than 2.5 microm. The correlations between SEM/EDX and XRD data seem to suggest that the airborne silica particles in the urban location studied consisted mostly of crystalline silica. Moreover, the data suggest the existence of a significant contribution of silica particles due to southwest wind carrying a fine dust from the Sahara desert to Mediterranean Europe.

Elucidating the Wavelength Dependence of Phonon Scattering in Nanoparticle-Matrix Composites using Phonon Spectroscopy

DTIC Science & Technology

2016-07-11

composites with x - ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy...RBS), particle-induced x - ray emission (PIXE), and energy dispersive x - ray spectroscopy (EDX). This work complements earlier works on CdSe...sample shows only In2Se3 and CdIn2Se4 XRD peaks (Figure 1.4e), it is stoichiometrically   Figure 1.4. X - ray diffraction patterns of (a) γ-In2Se3

Gold nanoparticle flow sensors designed for dynamic X-ray imaging in biofluids.

PubMed

Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Kim, Hae Koo; Lee, Sang Joon

2010-07-27

X-ray-based imaging is one of the most powerful and convenient methods in terms of versatility in applicable energy and high performance in use. Different from conventional nuclear medicine imaging, contrast agents are required in X-ray imaging especially for effectively targeted and molecularly specific functions. Here, in contrast to much reported static accumulation of the contrast agents in targeted organs, dynamic visualization in a living organism is successfully accomplished by the particle-traced X-ray imaging for the first time. Flow phenomena across perforated end walls of xylem vessels in rice are monitored by a gold nanoparticle (AuNP) (approximately 20 nm in diameter) as a flow tracing sensor working in nontransparent biofluids. AuNPs are surface-modified to control the hydrodynamic properties such as hydrodynamic size (DH), zeta-potential, and surface plasmonic properties in aqueous conditions. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray nanoscopy (XN), and X-ray microscopy (XM) are used to correlate the interparticle interactions with X-ray absorption ability. Cluster formation and X-ray contrast ability of the AuNPs are successfully modulated by controlling the interparticle interactions evaluated as flow-tracing sensors.

Alkyl group effects on CO insertion into coordinatively unsaturated early-transition-metal alkyls. Preparations and the first structural characterizations of tantalum enolate-O and tantalum. eta. sup 2 -acyl complexes

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

Meyer, T.Y.; Garner, L.R.; Baenziger, N.C.

1990-10-03

Low-pressure carbonylation of the mono(peralkylcyclopentadienyl)tantalum(V) alkyls ({eta}-C{sub 5}Me{sub 4}R)TaR{prime}Cl{sub 3} (R = Me, Et; R{prime} = CH{sub 2}C{sub 6}H{sub 4}-p-Me, CH{sub 2}CMe{sub 3}) yields either the O-bound enolate or the {eta}{sup 2}-acyl as shown by ir/NMR spectroscopy and x-ray diffractometry. The p-tolyl enolate ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3}, derived directly from carbonylation of the tantalum 4-methylbenzyl precursor, is shown to possess a cis configuration in solution and in the solid state. Key structural features from a single-crystal x-ray diffraction study of the tetrahydrofuran-ligated enolate complex are reported. The mechanism of formation of the enolate from carbonylation of themore » 4-methylbenzyl complex is discussed. The previously reported acyl ({eta}-C{sub 5}Me{sub 4}R)Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3} has been reexamined and found to possess a symmetric, strongly distorted {eta}{sup 2}-acyl coordination by solution {sup 1}H NMR spectroscopy and solid-state x-ray diffractometry. The molecular structures of ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3} and ({eta}-C{sub 5}Me{sub 5})Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3}, which are reported here, are the first structural determinations of a tantalum enolate and of a tantalum {eta}{sup 2}-acyl. 41 refs., 2 figs., 8 tabs.« less

Intracellular distribution and stability of a luminescent rhenium(I) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging

DOE PAGES

Wedding, Jason L.; Harris, Hugh H.; Bader, Christie A.; ...

2016-11-23

Optical fluorescence microscopy was used in conjunction with X-ray fluorescence microscopy to monitor the stability and intracellular distribution of the luminescent rhenium(I) complex fac-[Re(CO) 3(phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex, in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence techniques. Furthermore, X-ray fluorescence also showed that the Re-I complex disrupted the homeostasis of some biologically relevant elements,more » such as chlorine, potassium and zinc.« less

Symposium N: Materials and Devices for Thermal-to-Electric Energy Conversion

DTIC Science & Technology

2010-08-24

X - ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements...SEM), X - ray diffraction (XRD) measurements as well as Raman spectroscopy. The results from these techniques indicate a clear modification...was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x - ray spectroscopy. The electrical

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials.

PubMed

Du, Ming; Jacobsen, Chris

2018-01-01

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zero loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 µm (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Finally, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified. Copyright © 2017 Elsevier B.V. All rights reserved.

X-Ray Absorption Microspectroscopy with Electrostatic Force Microscopy and its Application to Chemical States Mapping

NASA Astrophysics Data System (ADS)

Ishii, M.; Rigopoulos, N.; Poolton, N. R. J.; Hamilton, B.

2007-02-01

A new technique named X-EFM that measures the x-ray absorption fine structure (XAFS) of nanometer objects was developed. In X-EFM, electrostatic force microscopy (EFM) is used as an x-ray absorption detector, and photoionization induced by x-ray absorption of surface electron trapping sites is detected by EFM. An EFM signal with respect to x-ray photon energy provides the XAFS spectra of the trapping sites. We adopted X-EFM to observe Si oxide thin films. An edge jump shift intrinsic to the X-EFM spectrum was found, and it was explained with a model where an electric field between the trapping site and probe deepens the energy level of the inner-shell. A scanning probe under x-rays with fixed photon energy provided the chemical state mapping on the surface.

Advantages of intermediate X-ray energies in Zernike phase contrast X-ray microscopy.

PubMed

Wang, Zhili; Gao, Kun; Chen, Jian; Hong, Youli; Ge, Xin; Wang, Dajiang; Pan, Zhiyun; Zhu, Peiping; Yun, Wenbing; Jacobsen, Chris; Wu, Ziyu

2013-01-01

Understanding the hierarchical organizations of molecules and organelles within the interior of large eukaryotic cells is a challenge of fundamental interest in cell biology. Light microscopy is a powerful tool for observations of the dynamics of live cells, its resolution attainable is limited and insufficient. While electron microscopy can produce images with astonishing resolution and clarity of ultra-thin (<1 μm thick) sections of biological specimens, many questions involve the three-dimensional organization of a cell or the interconnectivity of cells. X-ray microscopy offers superior imaging resolution compared to light microscopy, and unique capability of nondestructive three-dimensional imaging of hydrated unstained biological cells, complementary to existing light and electron microscopy. Until now, X-ray microscopes operating in the "water window" energy range between carbon and oxygen k-shell absorption edges have produced outstanding 3D images of cryo-preserved cells. The relatively low X-ray energy (<540 eV) of the water window imposes two important limitations: limited penetration (<10 μm) not suitable for imaging larger cells or tissues, and small depth of focus (DoF) for high resolution 3D imaging (e.g., ~1 μm DoF for 20 nm resolution). An X-ray microscope operating at intermediate energy around 2.5 keV using Zernike phase contrast can overcome the above limitations and reduces radiation dose to the specimen. Using a hydrated model cell with an average chemical composition reported in literature, we calculated the image contrast and the radiation dose for absorption and Zernike phase contrast, respectively. The results show that an X-ray microscope operating at ~2.5 keV using Zernike phase contrast offers substantial advantages in terms of specimen size, radiation dose and depth-of-focus. Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical imaging analysis of the brain with X-ray methods

NASA Astrophysics Data System (ADS)

Collingwood, Joanna F.; Adams, Freddy

2017-04-01

Cells employ various metal and metalloid ions to augment the structure and the function of proteins and to assist with vital biological processes. In the brain they mediate biochemical processes, and disrupted metabolism of metals may be a contributing factor in neurodegenerative disorders. In this tutorial review we will discuss the particular role of X-ray methods for elemental imaging analysis of accumulated metal species and metal-containing compounds in biological materials, in the context of post-mortem brain tissue. X-rays have the advantage that they have a short wavelength and can penetrate through a thick biological sample. Many of the X-ray microscopy techniques that provide the greatest sensitivity and specificity for trace metal concentrations in biological materials are emerging at synchrotron X-ray facilities. Here, the extremely high flux available across a wide range of soft and hard X-rays, combined with state-of-the-art focusing techniques and ultra-sensitive detectors, makes it viable to undertake direct imaging of a number of elements in brain tissue. The different methods for synchrotron imaging of metals in brain tissues at regional, cellular, and sub-cellular spatial resolution are discussed. Methods covered include X-ray fluorescence for elemental imaging, X-ray absorption spectrometry for speciation imaging, X-ray diffraction for structural imaging, phase contrast for enhanced contrast imaging and scanning transmission X-ray microscopy for spectromicroscopy. Two- and three-dimensional (confocal and tomographic) imaging methods are considered as well as the correlation of X-ray microscopy with other imaging tools.

X-ray microscopy of human malaria

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

Magowan, C.; Brown, J.T.; Mohandas, N.

Associations between intracellular organisms and host cells are complex and particularly difficult to examine. X-ray microscopy provides transmission images of subcellular structures in intact cells at resolutions superior to available methodologies. The spatial resolution is 50-60nm with a 1 micron depth of focus, superior to anything achievable with light microscopy. Image contrast is generated by differences in photoelectric absorption by the atoms in different areas (i.e. subcellular structures) throughout the full thickness of the sample. Absorption due to carbon dominates among all the elements in the sample at 2.4 nm x-ray wavelength. Thus images show features or structures, in amore » way not usually seen by other types of microscopy. The authors used soft x-ray microscopy to investigate structural development of Plasmodium falciparum malaria parasites in normal and genetically abnormal erythrocytes, and in infected erythrocytes treated with compounds that have anti-malarial effects. X-ray microscopy showed newly elaborated structures in the cytosol of unstained, intact erythrocytes, redistribution of mass (carbon) in infected erythrocytes, and aberrant parasite morphology. Better understanding of the process of intracellular parasite maturation and the interactions between the parasite and its host erythrocyte can help define new approaches to the control of this deadly disease.« less

A hard X-ray nanoprobe beamline for nanoscale microscopy.

PubMed

Winarski, Robert P; Holt, Martin V; Rose, Volker; Fuesz, Peter; Carbaugh, Dean; Benson, Christa; Shu, Deming; Kline, David; Stephenson, G Brian; McNulty, Ian; Maser, Jörg

2012-11-01

The Hard X-ray Nanoprobe Beamline (or Nanoprobe Beamline) is an X-ray microscopy facility incorporating diffraction, fluorescence and full-field imaging capabilities designed and operated by the Center for Nanoscale Materials and the Advanced Photon Source at Sector 26 of the Advanced Photon Source at Argonne National Laboratory. This facility was constructed to probe the nanoscale structure of biological, environmental and material sciences samples. The beamline provides intense focused X-rays to the Hard X-ray Nanoprobe (or Nanoprobe) which incorporates Fresnel zone plate optics and a precision laser sensing and control system. The beamline operates over X-ray energies from 3 to 30 keV, enabling studies of most elements in the periodic table, with a particular emphasis on imaging transition metals.

Soft X-Ray Diffraction Microscopy of a Frozen Hydrated Yeast Cell

DOE PAGES

Huang, Xiaojing; Nelson, Johanna; Kirz, Janos; ...

2009-11-01

We report the first image of an intact, frozen hydrated eukaryotic cell using x-ray diffraction microscopy, or coherent x-ray diffraction imaging. By plunge freezing the specimen in liquid ethane and maintaining it below -170 °C, artifacts due to dehydration, ice crystallization, and radiation damage are greatly reduced. In this example, coherent diffraction data using 520 eV x rays were recorded and reconstructed to reveal a budding yeast cell at a resolution better than 25 nm. This demonstration represents an important step towards high resolution imaging of cells in their natural, hydrated state, without limitations imposed by x-ray optics.

p-type zinc-blende GaN on GaAs substrates

NASA Astrophysics Data System (ADS)

Lin, M. E.; Xue, G.; Zhou, G. L.; Greene, J. E.; Morkoç, H.

1993-08-01

We report p-type cubic GaN. The Mg-doped layers were grown on vicinal (100) GaAs substrates by plasma-enhanced molecular beam epitaxy. Thermally sublimed Mg was, with N2 carrier gas, fed into an electron-cyclotron resonance source. p-type zinc-blende-structure GaN films were achieved with hole mobilities as high as 39 cm2/V s at room temperature. The cubic nature of the films were confirmed by x-ray diffractometry. The depth profile of Mg was investigated by secondary ions mass spectroscopy.

Thermally Stable Nanocrystalline Steel

NASA Astrophysics Data System (ADS)

Hulme-Smith, Christopher Neil; Ooi, Shgh Woei; Bhadeshia, Harshad K. D. H.

2017-10-01

Two novel nanocrystalline steels were designed to withstand elevated temperatures without catastrophic microstructural changes. In the most successful alloy, a large quantity of nickel was added to stabilize austenite and allow a reduction in the carbon content. A 50 kg cast of the novel alloy was produced and used to verify the formation of nanocrystalline bainite. Synchrotron X-ray diffractometry using in situ heating showed that austenite was able to survive more than 1 hour at 773 K (500 °C) and subsequent cooling to ambient temperature. This is the first reported nanocrystalline steel with high-temperature capability.

Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

NASA Astrophysics Data System (ADS)

Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.

2012-06-01

Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

Growth and Electronic Structure of Heusler Compounds for Use in Electron Spin Based Devices

DTIC Science & Technology

2015-06-01

either Co– or MnSi– initiated films on c(4x4) GaAs. Studies using x - ray photoemission spectroscopy (XPS), STM/STS, and transmission electron microscopy...Co– or MnSi– initiated films on c(4x4) GaAs. Studies using x - ray photoemission spectroscopy (XPS), STM/STS, and transmission electron microscopy (TEM...diagram of the Palmstrøm lab in-situ growth and char- acterization setup, with 6 MBE growth chambers, 3 scanning probe microscopes, an x - ray

Publications - GMC 58 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 58 Publication Details Title: X-ray diffraction and scanning electron microscopy mineral , Michael, and Core Laboratories, 1985, X-ray diffraction and scanning electron microscopy mineral analyses

X-ray ptychographic and fluorescence microscopy of frozen-hydrated cells using continuous scanning

DOE PAGES

Deng, Junjing; Vine, David J.; Chen, Si; ...

2017-03-27

X-ray microscopy can be used to image whole, unsectioned cells in their native hydrated state. It complements the higher resolution of electron microscopy for submicrometer thick specimens, and the molecule-specific imaging capabilites of fluorescence light microscopy. We describe here the first use of fast, continuous x-ray scanning of frozen hydrated cells for simultaneous sub-20 nm resolution ptychographic transmission imaging with high contrast, and sub-100 nm resolution deconvolved x-ray fluorescence imaging of diffusible and bound ions at native concentrations, without the need to add specific labels. Here, by working with cells that have been rapidly frozen without the use of chemicalmore » fixatives, and imaging them under cryogenic conditions, we are able to obtain images with well preserved structural and chemical composition, and sufficient stability against radiation damage to allow for multiple images to be obtained with no observable change.« less

Cryotomography x-ray microscopy state

DOEpatents

Le Gros, Mark; Larabell, Carolyn A.

2010-10-26

An x-ray microscope stage enables alignment of a sample about a rotation axis to enable three dimensional tomographic imaging of the sample using an x-ray microscope. A heat exchanger assembly provides cooled gas to a sample during x-ray microscopic imaging.

PREFACE: XTOP 2004 -- 7th Biennial Conference on High Resolution X-Ray Diffraction and Imaging

NASA Astrophysics Data System (ADS)

Holý, Vaclav

2005-05-01

The 7th Biennial Conference on High Resolution X-Ray Diffraction and Imaging (XTOP 2004) was held in the Prague suburb of Pruhonice, Czech Republic, during 7-10 September 2004. It was organized by the Czech and Slovak Crystallographic Association in cooperation with the Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Masaryk University, Brno, and Charles University, Prague. XTOP 2004 took place just after EPDIC IX (European Powder Diffraction Conference) organised in Prague by the same Association during 2-5 September 2004. The Organizing Committee was supported by an International Programme Committee including about 20 prominent scientists from several European and overseas countries, whose helpful suggestions for speakers are acknowledged. The conference was sponsored by the International Union of Crystallography and by several industrial sponsors; this sponsorship allowed us to support about 20 students and young scientists. In total, 147 official delegates and 8 accompanying persons from 16 countries of three continents attended our conference. The scientific programme of the conference was divided into 11 half-day sessions and 2 poster sessions. The participants presented 147 accepted contributions; of these 9 were 45-minute long invited talks, 34 were 20-minute oral presentations and 104 were posters. All posters were displayed for the whole meeting to ensure maximum exposure and interaction between delegates. We followed the very good experience from the previous conference, XTOP 2002, and also organized pre-conference tutorial lectures presented by experts in the field: `Imaging with hard synchrotron radiation' (J Härtwig, Grenoble), `High-resolution x-ray diffractometry: determination of strain and composition' (J Stangl, Linz), `X-ray grazing-incidence scattering from surfaces and nanostructures' (U Pietsch, Potsdam) and `Hard x-ray optics' (J Hrdý, Prague). According to the recommendation of the International Program Committee, the invited lectures covered a broader field than the original conference subject, namely coherent speckle diffraction (I Robinson, Urbana), scattering from soft-matter films (W de Jeu, Amsterdam), femtosecond diffraction (J Wark, Oxford), magnetic soft x-ray microscopy (P Fischer, Stuttgart), x-ray standing-wave imaging (J Zegenhagen, Grenoble), new trends in hard x-ray imaging (J Baruchel, Grenoble), anomalous x-ray scattering from nanostructures, (T Schülli, Grenoble), in-situ x-ray scattering (G Renaud, Grenoble) and x-ray waveguides (W Jark, Trieste). The topics of the oral presentations and posters can be divided into two large groups, namely x-ray imaging and x-ray diffraction. In the first group, the contributions concentrated on new developments in methods and instrumentation, including in-situ imaging, phase-contrast imaging and three-dimensional imaging. In the second group, attention was paid to anomalous scattering methods and scattering from thin films and nanostructures. The full list of all contributions together with their abstracts are available at the website http://www.xray.cz/xtop. During one session, Professor Andrew Lang, one of the pioneers of x-ray topography who gave his name to the popular topographic technique, and honorary guest of XTOP 2004, celebrated his 80th birthday. In a celebration address Professor A Authier reviewed Professor Lang's career and his invaluable contribution to the development of our field. We continue the tradition of previous XTOPs and publish a selection of original contributions from the conference in this special issue of Journal of Physics D: Applied Physics. The papers have been subject to peer review according to the normal practice of the journal. Generally, we observed that a new generation of young and very talented scientists has appeared, who are publishing very interesting and important papers. Therefore, the future prospects of x-ray imaging and high-resolution diffraction are bright and we all look forward to the next XTOP conference, organized by Tilo Baumbach and his group, which will take place in Karlsruhe, Germany, in 2006.

Characterization of X80 and X100 Microalloyed Pipeline Steel Using Quantitative X-ray Diffraction

NASA Astrophysics Data System (ADS)

Wiskel, J. B.; Li, X.; Ivey, D. G.; Henein, H.

2018-06-01

Quantitative X-ray diffraction characterization of four (4) X80 and three (3) X100 microalloyed steels was undertaken. The effect of through-thickness position, processing parameters, and composition on the measured crystallite size, microstrain, and J index (relative magnitude of crystallographic texture) was determined. Microstructure analysis using optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron-backscattered diffraction was also undertaken. The measured value of microstrain increased with increasing alloy content and decreasing cooling interrupt temperature. Microstructural features corresponding to crystallite size in the X80 steels were both above and below the detection limit for quantitative X-ray diffraction. The X100 steels consistently exhibited microstructure features below the crystallite size detection limit. The yield stress of each steel increased with increasing microstrain. The increase in microstrain from X80 to X100 is also associated with a change in microstructure from predominantly polygonal ferrite to bainitic ferrite.

Ferric ion-assisted in situ synthesis of silver nanoplates on polydopamine-coated silk.

PubMed

Xiao, Jing; Zhang, Huihui; Mao, Cuiping; Wang, Ying; Wang, Ling; Lu, Zhisong

2016-10-01

In the present study, a ferric ion (Fe(3+))-assisted in situ synthesis approach was developed to grow silver (Ag) nanoplates on the polydopamine (PDA)-coated silk without the use of additional reductants. The essential role of Fe(3+) in the formation of Ag nanoplates is revealed by comparing the morphologies of Ag nanostructures prepared on the silk-coated PDA film with/without Fe(3+) doping. Scanning electron micrographs show that high-density Ag nanoplates could be synthesized in the reaction system containing 50μg/mL FeCl3 and 50mM AgNO3. The size of the Ag nanoplate could be tuned by adjusting the reaction duration. Based on the data, a mechanism involving the Fe(3+)-selected growth of Ag atoms along the certain crystal faces was proposed to explain the fabrication process. Transmission electron microscopy and X-ray diffractometry indicate that the Ag nanoplates possess good crystalline structures. Raman spectra demonstrate that the nanoplates could strongly enhance the Raman scattering of the PDA molecules. The Ag nanoplate-coated silk could be utilized as a flexible substrate for the development of surface-enhanced Raman scattering biosensors. Copyright © 2016 Elsevier Inc. All rights reserved.

One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications.

PubMed

Cai, Rui; Tao, Gang; He, Huawei; Song, Kai; Zuo, Hua; Jiang, Wenchao; Wang, Yejing

2017-04-30

Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs) modified on polydopamine-coated sericin/polyvinyl alcohol (PVA) composite films was developed. Polydopamine (PDA) acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine.

Molecular inclusion complex of curcumin-β-cyclodextrin nanoparticle to enhance curcumin skin permeability from hydrophilic matrix gel.

PubMed

Rachmawati, Heni; Edityaningrum, Citra Ariani; Mauludin, Rachmat

2013-12-01

Curcumin (CUR) has various pharmacological effects, but its extensive first-pass metabolism and short elimination half-life limit its bioavailability. Therefore, transdermal application has become a potential alternative to delivery CUR. To increase CUR solubility for the development of a transparent homogenous gel and also enhance the permeation rate of CUR into the skin, β-cyclodextrin-curcumin nanoparticle complex (BCD-CUR-N) was developed. CUR encapsulation efficiency was increased by raising the percentage of CUR to BCD up to 20%. The mean particle size of the best CUR loading formula was 156 nm. All evaluation data using infrared spectroscopy, Raman spectroscopy, powder X-ray diffractometry, differential thermal analysis and scanning electron microscopy confirmed the successful formation of the inclusion complex. BCD-CUR-N increased the CUR dissolution rate of 10-fold (p < 0.01). In addition, the improvement of CUR permeability acrossed skin model tissue was observed in gel containing the BCD-CUR-N and was about 1.8-fold when compared with the free CUR gel (p < 0.01). Overall, CUR in the form of the BCD-CUR-N improved the solubility further on the penetration of CUR.

Dissolution enhancement of tadalafil by liquisolid technique.

PubMed

Lu, Mei; Xing, Haonan; Yang, Tianzhi; Yu, Jiankun; Yang, Zhen; Sun, Yanping; Ding, Pingtian

2017-02-01

This study aimed to enhance the dissolution of tadalafil, a poorly water-soluble drug by applying liquisolid technique. The effects of two critical formulation variables, namely drug concentration (17.5% and 35%, w/w) and excipients ratio (10, 15 and 20) on dissolution rates were investigated. Pre-compression tests, including particle size distribution, flowability determination, Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and scanning electron microscopy (SEM), were carried out to investigate the mechanism of dissolution enhancement. Tadalafil liquisolid tablets were prepared and their quality control tests, dissolution study, contact angle measurement, Raman mapping, and storage stability test were performed. The results suggested that all the liquisolid tablets exhibited significantly higher dissolution rates than the conventional tablets and pure tadalafil. FT-IR spectrum reflected no drug-excipient interactions. DSC and XRD studies indicated reduction in crystallinity of tadalafil, which was further confirmed by SEM and Raman mapping outcomes. The contact angle measurement demonstrated obvious increase in wetting property. Taken together, the reduction of particle size and crystallinity, and the improvement of wettability were the main mechanisms for the enhanced dissolution rate. No significant changes were observed in drug crystallinity and dissolution behavior after storage based on XRD, SEM and dissolution results.

Synthesis and surface properties of submicron barium sulfate particles

NASA Astrophysics Data System (ADS)

Zhang, Ming; Zhang, Bao; Li, Xinhai; Yin, Zhoulan; Guo, Xueyi

2011-10-01

Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO 4 particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO 4 particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO 4 were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaSO 4 was presented. The FTIR result indicates that the surface of the prepared BaSO 4 absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.

Formation and characterization of calcium orthophosphates in the presence of two different acidic macromolecules

NASA Astrophysics Data System (ADS)

Pelin, Irina M.; Maier, Vasilica; Suflet, Dana M.; Popescu, Irina; Darie-Nita, Raluca N.; Aflori, Magdalena; Butnaru, Maria

2017-10-01

The synthetic nanocrystalline calcium orthophosphates have a notable bioactivity due to the chemical similarity with biological apatite from calcified tissues. In mineralized tissues, the highly ordered structures come from organized assemblies of biomacromolecules and inorganic nanoparticles. One of the purposes of this work was to study the effect of two types of acidic macromolecules: atelocollagen and phosphorylated curdlan onto calcium orthophosphates formation after 30 days of maturation at 2 ± 2 °C. The resulted samples after a long aging time, either calcium orthophosphates or composites, were first investigated by FT-IR spectroscopy and X-ray diffractometry and the results indicated that precipitated hydroxyapatite with low crystallinity was obtained when the synthesis was performed in the presence of phosphorylated curdlan. The macromolecules influenced the morphology of the particles as shown by scanning and transmission electron microscopy. The presence of macromolecules as demonstrated by thermal investigation also influenced the rheological properties of the samples. The second purpose of the work was to evaluate the cytotoxicity of the samples using the MTT assay, and the results revealed very good cells viability. The preliminary results are encouraging regarding the use of these materials for further tests in order to develop injectable bone substitutes.

Structural and optical properties of low temperature grown AlN films on sapphire using helicon sputtering system

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

Chen, Meei-Ru; Chen, Hou-Guang; Kao, Hui-Ling, E-mail: hlkao@cycu.edu.tw

2015-05-15

AlN thin films have been deposited directly on c-plane sapphire substrates at low temperatures by a helicon sputtering system. The structural quality of AlN epitaxial films was characterized by x-ray diffractometry and transmission electron microscopy. The films exhibit smooth surface with root-mean-square roughness as small as 0.7 nm evaluated by atomic force microscope. The optical transmittance spectra show a steep absorption edge at the wavelength of 200 nm and a high transmittance of over 80% in the visible range. The band-edge transition (6.30 eV) of AlN film was observed in the cathodoluminescence spectrum recorded at 11 K. The spectral response of metal–semiconductor–metal photodetectors constructedmore » with AlN/sapphire reveals the peak responsivity at 200 nm and a UV/visible rejection ratio of about two orders of magnitude. The results of this low temperature deposition suggest the feasibility of the epitaxial growth of AlN on sapphire substrates and the incorporation of the AlN films in the surface acoustic wave devices and the optical devices at deep ultraviolet region.« less

Structural characterization and bioavailability of ternary nanoparticles consisting of amylose, α-linoleic acid and β-lactoglobulin complexed with naringin.

PubMed

Feng, Tao; Wang, Ke; Liu, Fangfang; Ye, Ran; Zhu, Xiao; Zhuang, Haining; Xu, Zhimin

2017-06-01

Naringin is a bioflavonoid that is rich in citrus plants and possesses enormous health benefits. However, the use of naringin as a nutraceutical is significantly limited by its low bioavailability. In this study, a novel water-soluble ternary nanoparticle material consisting of amylose, α-linoleic acid and β-lactoglobulin was developed to encapsulate naringin to improve its bioavailability. The physicochemical characteristics of the ternary nanoparticle-naringin inclusion complex were analysed by ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), high-resolution transmission electron microscopy (TEM), X-ray diffractometry (XRD) and particle size distribution. The results confirmed the formation of the ternary nanoparticle-naringin inclusion complex. The encapsulation efficiency (EE) and loading content (LC) of the ternary nanoparticle-naringin inclusion complex were 78.73±4.17% and 14.51±3.43%, respectively. In addition, the results of the ternary nanoparticle-naringin inclusion complex in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) demonstrated that naringin can be gradually released from the complex. In conclusion, ternary nanoparticles are considered promising carriers to effectively improve the bioavailability of naringin. Copyright © 2017 Elsevier B.V. All rights reserved.

LiMn2O4–yBryNanoparticles Synthesized by a Room Temperature Solid-State Coordination Method

PubMed Central

2009-01-01

LiMn2O4–yBrynanoparticles were synthesized successfully for the first time by a room temperature solid-state coordination method. X-ray diffractometry patterns indicated that the LiMn2O4–yBrypowders were well-crystallized pure spinel phase. Transmission electron microscopy images showed that the LiMn2O4–yBrypowders consisted of small and uniform nanosized particles. Synthesis conditions such as the calcination temperature and the content of Br−were investigated to optimize the ideal condition for preparing LiMn2O4–yBrywith the best electrochemical performances. The optimized synthesis condition was found in this work; the calcination temperature is 800 °C and the content of Br−is 0.05. The initial discharge capacity of LiMn2O3.95Br0.05obtained from the optimized synthesis condition was 134 mAh/g, which is far higher than that of pure LiMn2O4, indicating introduction of Br−in LiMn2O4is quite effective in improving the initial discharge capacity. PMID:20628635

Modification of the crystal habit of celecoxib for improved processability.

PubMed

Banga, Sheere; Chawla, Garima; Varandani, Deepak; Mehta, B R; Bansal, Arvind K

2007-01-01

Crystallization is often used in the pharmaceutical industry for purification and isolation of drugs, and also as a means of generating polymorphs or isomorphs. The aim of this study was to investigate the role of extrinsic crystallization parameters on the crystallized product, with special emphasis on improving the mechanical properties of acicular celecoxib. Celecoxib isomorphs were prepared using different techniques (solvent crystallization and vapour diffusion) and crystallization conditions (solvents, stirring, degree of supersaturation, crystallization temperature and seeding). Powder X-ray diffractometry, spectroscopic and thermal methods were used to investigate physical characteristics of crystals. Growth kinetics and aggregation dynamics of crystallization in polar and non-polar solvents were simulated using a dynamic light scattering method. The quick appearance of broad peaks over the range of 10-8000 nm in chloroform during crystallization simulation studies indicated faster aggregation in non-polar solvents. Aspect ratio, flow, compressibility and surface area of recrystallized products were also determined. Surface topography was determined by atomic force microscopy and the lath-shaped crystals (aspect ratio of 2-4) exhibited a roughness index of 1.79 in comparison with 2.92 for needles. Overall, the lath-shaped isomorphs exhibited improved flow and better compressibility.

Synthesis and characterization of ferrite-semiconductor nano composite for photocatalytic degradation of aqueous nitrobenzene solution

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

Modi, K. B.; Kathad, C. R.; Raval, P. Y.

2016-05-06

Nanoparticles of semiconductor TiO{sub 2}, zinc ferrite (ZnFe{sub 2}O{sub 4}) and ZnFe{sub 2}O{sub 4}-TiO{sub 2} composite, were synthesized by auto combustion route. Subsequent characterization of synthesized photocatalysts was carried out by X-ray powder diffractometry, transmission electron microscopy, UV-Vis-Diffuse Reflectance Spectroscopy to study the structural and textural properties. The specific surface area, pore diameter and pore volume of synthesized materials were investigated by N{sub 2} adsorption analysis while the presence of TiO{sub 2} in the composite material was verified by infrared spectral analysis. The photocatalytic activity of synthesized photocatalysts was evaluated by degradation of nitrobenzene (NB) in aqueous medium under irradiationmore » of ultraviolet light. The result revealed that 77, 73 and 70% of NB was degraded using TiO{sub 2}, ZnFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4}-TiO{sub 2} photocatalysts after 4h in the presence of UV irradiation. The composite photocatalyst was found easy to separate from the treated solution.« less

Photocatalytic degradation of an azo textile dye (C.I. Reactive Red 195 (3BF)) in aqueous solution over copper cobaltite nanocomposite coated on glass by Doctor Blade method.

PubMed

Habibi, Mohammad Hossein; Rezvani, Zoya

2015-08-05

The degradation of C.I. Reactive Red 195 (3BF) in aqueous solution using copper cobaltite nanocomposite coated on glass by Doctor Blade method was studied. Structural, optical and morphological properties of nanocomposite coatings were characterized by X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and field emission scanning electron microscopy (FESEM). The nanoparticles exhibit a particle size of 31 nm, showing a good nanoscale crystalline morphology. The photocatalytic activity of copper cobaltite nanocomposite coated on glass was studied by performing the photocatalytic degradation of 3BF at different irradiation time. The effect of irradiation time on the degradation of 3BF was studied and the results showed that more than 85% of the 3BF was degraded in 45 min of irradiation. The pseudo-first-order kinetic models were used and the rate constants were evaluated with pseudo first order rate constants of 4.10 × 10(-2) min(-1). The main advantage of the photocatalyst coated on glass overcomes the difficulties in separation and recycle of photocatalyst suspensions. Copyright © 2015 Elsevier B.V. All rights reserved.

Piroxicam/2-hydroxypropyl-beta-cyclodextrin inclusion complex prepared by a new fluid-bed coating technique.

PubMed

Zhang, Xingwang; Wu, Danni; Lai, Jie; Lu, Yi; Yin, Zongning; Wu, Wei

2009-02-01

This work was aimed at investigating the feasibility of fluid-bed coating as a new method to prepare cyclodextrin inclusion complex. The inclusion complex of the model drug piroxicam (PIX) and 2-hydroxypropyl-beta-cyclodextrin (HPCD) in aqueous ethanol solution was sprayed and deposited onto the surface of the pellet substrate upon removal of the solvent. The coating process was fluent with high coating efficiency. Scanning electron microscopy revealed a coarse pellet surface, and a loosely packed coating structure. Significantly enhanced dissolution, over 90% at 5 min, was observed at stoichiometric PIX/HPCD molar ratio (1/1) and at a ratio with excessive HPCD (1/2). Differential scanning calorimetry and powder X-ray diffractometry confirmed absence of crystallinity of PIX at PIX/HPCD molar ratio of 1/1 and 1/2. Fourier transform-infrared spectrometry and Raman spectrometry revealed interaction between PIX and HPCD adding evidence on inclusion of PIX moieties into HPCD cavities. Solid-state (13)C NMR spectrometry indicated possible inclusion of PIX through the pyridine ring. It is concluded that fluid-bed coating has potential to be used as a new technique to prepare cyclodextrin inclusion complex.

A hard X-ray nanoprobe beamline for nanoscale microscopy

PubMed Central

Winarski, Robert P.; Holt, Martin V.; Rose, Volker; Fuesz, Peter; Carbaugh, Dean; Benson, Christa; Shu, Deming; Kline, David; Stephenson, G. Brian; McNulty, Ian; Maser, Jörg

2012-01-01

The Hard X-ray Nanoprobe Beamline (or Nanoprobe Beamline) is an X-ray microscopy facility incorporating diffraction, fluorescence and full-field imaging capabilities designed and operated by the Center for Nanoscale Materials and the Advanced Photon Source at Sector 26 of the Advanced Photon Source at Argonne National Laboratory. This facility was constructed to probe the nanoscale structure of biological, environmental and material sciences samples. The beamline provides intense focused X-rays to the Hard X-ray Nanoprobe (or Nanoprobe) which incorporates Fresnel zone plate optics and a precision laser sensing and control system. The beamline operates over X-ray energies from 3 to 30 keV, enabling studies of most elements in the periodic table, with a particular emphasis on imaging transition metals. PMID:23093770

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

Moraes, Paulo E.L., E-mail: pauloeduardo.leitedemoraes@gmail.com; Contieri, Rodrigo J., E-mail: contieri@fem.unicamp.br; Lopes, Eder S.N., E-mail: ederlopes@fem.unicamp.br

Ti and Ti alloys are widely used in restorative surgery because of their good biocompatibility, enhanced mechanical behavior and high corrosion resistance in physiological media. The corrosion resistance of Ti-based materials is due to the spontaneous formation of the TiO{sub 2} oxide film on their surface, which exhibits elevated stability in biological fluids. Ti–Nb alloys, depending on the composition and the processing routes to which the alloys are subjected, have high mechanical strength combined with low elastic modulus. The addition of Sn to Ti–Nb alloys allows the phase transformations to be controlled, particularly the precipitation of ω phase. The aimmore » of this study is to discuss the microstructure, mechanical properties and corrosion behavior of cast Ti–Nb alloys to which Sn has been added. Samples were centrifugally cast in a copper mold, and the microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffractometry. Mechanical behavior evaluation was performed using Berkovich nanoindentation, Vickers hardness and compression tests. The corrosion behavior was evaluated in Ringer's solution at room temperature using electrochemical techniques. The results obtained suggested that the physical, mechanical and chemical behaviors of the Ti–Nb–Sn alloys are directly dependent on the Sn content. - Graphical abstract: Effects of Sn addition to the Ti–30Nb alloy on the elastic modulus. - Highlights: • Sn addition causes reduction of the ω phase precipitation. • Minimum Vickers hardness and elastic modulus occurred for 6 wt.% Sn content. • Addition of 6 wt.% Sn resulted in maximum ductility and minimum compression strength. • All Ti–30Nb–XSn (X = 0, 2, 4, 6, 8 and 10%) alloys are passive in Ringer's solution. • Highest corrosion resistance was observed for 6 wt.% Sn content.« less

Quantitative 3D comparison of biofilm imaged by X-ray micro-tomography and two-photon laser scanning microscopy.

PubMed

Larue, A E; Swider, P; Duru, P; Daviaud, D; Quintard, M; Davit, Y

2018-06-21

Optical imaging techniques for biofilm observation, like laser scanning microscopy, are not applicable when investigating biofilm formation in opaque porous media. X-ray micro-tomography (X-ray CMT) might be an alternative but it finds limitations in similarity of X-ray absorption coefficients for the biofilm and aqueous phases. To overcome this difficulty, barium sulphate was used in Davit et al. (2011) to enable high-resolution 3D imaging of biofilm via X-ray CMT. However, this approach lacks comparison with well-established imaging methods, which are known to capture the fine structures of biofilms, as well as uncertainty quantification. Here, we compare two-photon laser scanning microscopy (TPLSM) images of Pseudomonas Aeruginosa biofilm grown in glass capillaries against X-ray CMT using an improved protocol where barium sulphate is combined with low-gelling temperature agarose to avoid sedimentation. Calibrated phantoms consisting of mono-dispersed fluorescent and X-ray absorbent beads were used to evaluate the uncertainty associated with our protocol along with three different segmentation techniques, namely hysteresis, watershed and region growing, to determine the bias relative to image binarization. Metrics such as volume, 3D surface area and thickness were measured and comparison of both imaging modalities shows that X-ray CMT of biofilm using our protocol yields an accuracy that is comparable and even better in certain respects than TPLSM, even in a nonporous system that is largely favourable to TPLSM. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Possible role of Prussian blue nanoparticles in chemical evolution: interaction with ribose nucleotides

NASA Astrophysics Data System (ADS)

Sharma, Rachana; Iqubal, Md. Asif; Kamaluddin

2016-01-01

Ribonucleotides (RMPs) are the building blocks of genetic material consisting of a sugar group, a phosphate group and a nucleobase. Prussian blue (PB) is an ancient compound which is supposed to have formed under the conditions of primitive Earth. The interaction between nucleotides and mineral surfaces is of primary importance in the context of prebiotic chemistry. In the present work, the adsorption of RMPs on PB has been studied in the concentration range 0.4 × 10-4-3.0 × 10-4 M of RMPs at pH 7.5, T = 27°C and found to be 53.1, 41.7, 25.8 and 24.0% for adenosine 5'-monophosphate (5'-AMP), guanosine 5'-monophosphate, cytidine 5'-monophosphate and uridine 5'-monophosphate, respectively. Optimum conditions for the adsorption were studied as a function of concentration, time, amount of adsorbent and pH and data obtained were found to fit the Langmuir adsorption isotherm. Langmuir constants (K L and X m ) values were calculated. Fourier transform infrared spectroscopy, Raman spectroscopy, field-emission scanning electron microscopy and X-ray diffractometry techniques were used to investigate the interaction of RMPs on PB surface. Adsorption kinetics of 5'-AMP on PB has been found to be pseudo-second order. Results obtained from this study should prove valuable for a better understanding of the mechanism of RMP-PB interaction.

Aplanatic Three-Mirror Objective for High-Magnification Soft X-Ray Microscopy

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

Toyoda, M.; Jinno, T.; Yanagihara, M.

2011-09-09

An innovative solution for high-magnification microscopy, based on attaching afocal optics for focal length reduction, is proposed. The solution, consisting of three spherical mirrors, allows one to enhance a magnification of a laboratory based soft x-ray microscope over 1000x, where movies with diffraction-limited resolution can be observed with an x-ray CCD. The design example, having a numerical aperture of 0.25, was successfully demonstrated both a high magnification and a large field of view.

Rapid disintegrating tablets of simvastatin dispersions in polyoxyethylene–polypropylene block copolymer for maximized disintegration and dissolution

PubMed Central

Balata, Gehan F; Zidan, Ahmad S; Abourehab, Mohamad AS; Essa, Ebtessam A

2016-01-01

The objective of this research was to improve the dissolution of simvastatin and to incorporate it in rapid disintegrating tablets (RDTs) with an optimized disintegration and dissolution characteristics. Polyoxyethylene–polypropylene block copolymer (poloxamer 188) was employed as a hydrophilic carrier to prepare simvastatin solid dispersions (SDs). Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and X-ray diffractometry were employed to understand the interaction between the drug and the carrier in the solid state. The results obtained from Fourier transform infrared spectroscopy showed absence of any chemical interaction between the drug and poloxamer. The results of differential scanning calorimetry and X-ray diffractometry confirmed the conversion of simvastatin to distorted crystalline state. The SD of 1:2 w/w drug to carrier ratio showed the highest dissolution; hence, it was incorporated in RDT formulations using a 32 full factorial design and response surface methodology. The initial assessments of RDTs demonstrated an acceptable flow, hardness, and friability to indicate good mechanical strength. The interaction and Pareto charts indicated that percentage of croscarmellose sodium incorporated was the most important factor affecting the disintegration time and dissolution parameter followed by the hardness value and their interaction effect. Compression force showed a superior influence to increase RDT’s porosity and to fasten disintegration rather than swelling action by croscarmellose sodium. On the other hand, croscarmellose sodium was most important for the initial simvastatin release. The results suggest the potential use of poloxamer 188-based SD in RDT for the oral delivery of poor water-soluble antihyperlipidemic drug, simvastatin. PMID:27757012

Cryogenic X-Ray Diffraction Microscopy for Biological Samples

NASA Astrophysics Data System (ADS)

Lima, Enju; Wiegart, Lutz; Pernot, Petra; Howells, Malcolm; Timmins, Joanna; Zontone, Federico; Madsen, Anders

2009-11-01

X-ray diffraction microscopy (XDM) is well suited for nondestructive, high-resolution biological imaging, especially for thick samples, with the high penetration power of x rays and without limitations imposed by a lens. We developed nonvacuum, cryogenic (cryo-) XDM with hard x rays at 8 keV and report the first frozen-hydrated imaging by XDM. By preserving samples in amorphous ice, the risk of artifacts associated with dehydration or chemical fixation is avoided, ensuring the imaging condition closest to their natural state. The reconstruction shows internal structures of intact D. radiodurans bacteria in their natural contrast.

Simultaneous scanning tunneling microscopy and synchrotron X-ray measurements in a gas environment.

PubMed

Mom, Rik V; Onderwaater, Willem G; Rost, Marcel J; Jankowski, Maciej; Wenzel, Sabine; Jacobse, Leon; Alkemade, Paul F A; Vandalon, Vincent; van Spronsen, Matthijs A; van Weeren, Matthijs; Crama, Bert; van der Tuijn, Peter; Felici, Roberto; Kessels, Wilhelmus M M; Carlà, Francesco; Frenken, Joost W M; Groot, Irene M N

2017-11-01

A combined X-ray and scanning tunneling microscopy (STM) instrument is presented that enables the local detection of X-ray absorption on surfaces in a gas environment. To suppress the collection of ion currents generated in the gas phase, coaxially shielded STM tips were used. The conductive outer shield of the coaxial tips can be biased to deflect ions away from the tip core. When tunneling, the X-ray-induced current is separated from the regular, 'topographic' tunneling current using a novel high-speed separation scheme. We demonstrate the capabilities of the instrument by measuring the local X-ray-induced current on Au(1 1 1) in 800 mbar Ar. Copyright © 2017 Elsevier B.V. All rights reserved.

Synchrotron X-ray microscopy and spectroscopy analysis of iron in hemochromatosis liver and intestines

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

Ko, J .Y. Peter; Sham, Tsun-Kong; Chakrabarti, Subrata

2009-12-01

Hemochromatosis is a genetic disorder that causes body to store excess iron in organs such as heart or liver. Distribution of iron, as well as copper, zinc and calcium, and chemical identity of iron in hemochromatosis liver and intestine were investigated by X-ray microprobe experiments, which consist of X-ray microscopy and micro-X-ray absorption fine structure. Our results show that iron concentration in hemochromatosis liver tissue is high, while much less Fe is found in intestinal tissue. Moreover, chemical identity of Fe in hemochromatosis liver can be identified. X-ray microprobe experiments allows for examining elemental distribution at an excellent spatial resolution.more » Moreover, chemical identity of element of interest can be obtained.« less

Observation of electromigration in a Cu thin line by in situ coherent x-ray diffraction microscopy

NASA Astrophysics Data System (ADS)

Takahashi, Yukio; Nishino, Yoshinori; Furukawa, Hayato; Kubo, Hideto; Yamauchi, Kazuto; Ishikawa, Tetsuya; Matsubara, Eiichiro

2009-06-01

Electromigration (EM) in a 1-μm-thick Cu thin line was investigated by in situ coherent x-ray diffraction microscopy (CXDM). Characteristic x-ray speckle patterns due to both EM-induced voids and thermal deformation in the thin line were observed in the coherent x-ray diffraction patterns. Both parts of the voids and the deformation were successfully visualized in the images reconstructed from the diffraction patterns. This result not only represents the first demonstration of the visualization of structural changes in metallic materials by in situ CXDM but is also an important step toward studying the structural dynamics of nanomaterials using x-ray free-electron lasers in the near future.

Preparation, characterization and cytotoxic evaluation of bovine serum albumin nanoparticles encapsulating 5-methylmellein: A secondary metabolite isolated from Xylaria psidii.

PubMed

Arora, Divya; Kumar, Amit; Gupta, Prasoon; Chashoo, Gousia; Jaglan, Sundeep

2017-12-01

In this study, 5-methylmellein (5-MM) loaded bovine serum albumin nanoparticles (BSA NPs) were developed using desolvation technique. The developed nanoparticles were characterized for their mean particle size, polydispersity, zeta potential, loading efficiency, X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and release profile. The developed nanoparticles were spherical in shape under transmission electron microscopy (TEM) and atomic force microscopy (AFM). The developed 5-MM loaded BSA NPs demonstrated a mean particle size with a diameter of 154.95 ± 4.44 nm. The results from XRD and DSC studies demonstrated that the crystal state of the 5-MM was converted to an amorphous state in polymeric matrix. The encapsulation and loading efficiency was found to be 73.26 ± 4.48% and 7.09 ± 0.43%. The in vitro cytotoxicity in human prostate cancer cell line (PC-3), human colon cancer cells (HCT-116) and human breast adenocarcinoma cell line (MCF-7) cells demonstrated enhanced cytotoxicity of 5-MM BSA NPs as compared to native 5-MM after 72-h treatment. The enhancement in cytotoxicity of 5-MM BSA NPs was also supported by increase in cellular apoptosis, mitochondrial membrane potential loss and generation of high reactive oxygen species (ROS). In conclusion, these findings collectively indicated that BSA nanoparticles may serve as promising drug delivery system for improving the efficacy of 5-methylmellein. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crystallization of D-mannitol in binary mixtures with NaCl: phase diagram and polymorphism.

PubMed

Telang, Chitra; Suryanarayanan, Raj; Yu, Lian

2003-12-01

To study the crystallization, polymorphism, and phase behavior of D-mannitol in binary mixtures with NaCl to better understand their interactions in frozen aqueous solutions. Differential scanning calorimetry, hot-stage microscopy, Raman microscopy, and variable-temperature X-ray diffractometry were used to characterize D-mannitol-NaCl mixtures. NaCl and D-mannitol exhibited significant melt miscibility (up to 7.5% w/w or 0.20 mole fraction of NaCl) and a eutectic phase diagram (eutectic composition 7.5% w/w NaCl; eutectic temperature 150 degrees C for the alpha and beta polymorphs of D-mannitol and 139 degrees C for the delta). The presence of NaCl did not prevent mannitol from crystallizing but, depending on sample size, affected the polymorph crystallized: below 10 mg, delta was obtained; above 100 mg, alpha was obtained. Pure mannitol crystallized under the same conditions first as the delta polymorph and then as the a polymorph, with the latter nucleating on the former. KCl showed similar eutectic points and melt miscibility with D-mannitol as NaCl. LiCl yielded lower eutectic melting points, inhibited the crystallization of D-mannitol during cooling, and enabled the observation of its glass transition. Despite their structural dissimilarity, significant melt miscibility exists between D-mannitol and NaCl. Their phase diagram has been determined and features polymorph-dependent eutectic points. NaCl influences the polymorphic behavior of mannitol, and the effect is linked to the crystallization of mannitol in two polymorphic stages.

He-irradiation effects on glass-ceramics for joining of SiC-based materials

NASA Astrophysics Data System (ADS)

Gozzelino, L.; Casalegno, V.; Ghigo, G.; Moskalewicz, T.; Czyrska-Filemonowicz, A.; Ferraris, M.

2016-04-01

CaO-Al2O3 (CA) and SiO2-Al2O3-Y2O3 (SAY) glass-ceramics are promising candidates for SiC/SiC indirect joints. In view of their use in locations where high radiation level is expected (i.e. fusion plants) it is important to investigate how radiation-induced damage can modify the material microstructure. To this aim, pellets of both types were irradiated with 5.5 MeV 4He+ ions at an average temperature of 75 °C up to a fluence of almost 2.3·1018 cm-2. This produces a displacement defect density that increases with depth and reaches a value of about 40 displacements per atom in the ion implantation region, where the He-gas reaches a concentration of several thousands of atomic parts per million. X-ray diffractometry and scanning electron microscopy showed no change in the microstructure and in the morphology of the pellet surface. Moreover, a transmission electron microscopy investigation on cross-section lamellas revealed the occurrence of structural defects and agglomerates of He-bubbles in the implantation region for the CA sample and a more homogeneous He-bubble distribution in the SAY pellet, even outside the implantation layer. In addition, no amorphization was found in both samples, even in correspondence to the He implantation zone. The radiation damage induced only occasional micro-cracks, mainly located at grain boundaries (CA) or within the grains (SAY).

Amorphous Sulfadoxine: A Physical Stability and Crystallization Kinetics Study.

PubMed

Aucamp, Marique; Milne, Marnus; Liebenberg, Wilna

2016-10-01

Poor aqueous solubility of drugs and the improvement thereof has always been a challenge for the pharmaceutical industry. With this, one of the focuses of the pharmaceutical research scientist involves investigating possible metastable forms of a given drug to be incorporated into solid dosage forms. The rationale being, the improved solubility offered by the metastable solid-state forms of drugs. Solubility remains a major challenge for formulation scientists, especially with antimicrobial agents where the emergence of resistance is directly dependent on the concentration and duration of the parasite exposed to the drug. Sulfadoxine-pyrimethamine combination therapies are still the recommended treatments for uncomplicated Plasmodium falciparum malaria. The aim of this study was to prepare an amorphous form of sulfadoxine and to investigate the stability and recrystallization behavior thereof. The amorphous form was prepared by the well-known quench cooling of the melt. The physico-chemical properties and stability of amorphous sulfadoxine were studied using hot-stage microscopy (HSM), scanning electron microscopy (SEM), x-ray powder diffractometry (XRPD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), as well as microcalorimetry. The recrystallization kinetics were studied isothermally by applying the Johnson-Mehl-Avrami model and non-isothermally by applying the Kissinger model. The physical stabilization of the amorphous form was investigated using physical mixtures of amorphous sulfadoxine with polyvinylpyrrolidone-25 (PVP-25). It was proved that sulfadoxine is a good glass former with relative high physical stability; however, water acts as a strong plasticizer for amorphous sulfadoxine, detrimentally affecting the stability during exposure to high moisture conditions.

Tribological Properties of Ti(Al,O)/Al2O3 Composite Coating by Thermal Spraying

NASA Astrophysics Data System (ADS)

Salman, Asma; Gabbitas, Brian; Cao, Peng; Zhang, Deliang

The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity air fuel (HVAF) thermally sprayed wear resistant Ti(Al,O)/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting and dummy blocks aluminium extrusion. A feedstock of Ti(Al,O)/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity air-fuel (HVAF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The wear resistance of the coating was investigated by a tribometer using a spherical ended alumina pin as a counter body under dry and lubricating conditions. The results showed that composite coating has lower wear rate at high temperature than at room temperature without using lubricant. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

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

Liu, Zheng; Li, Zhilin; Institute of Carbon Fibers and Composites, Beijing University of Chemical Technology, Beijing 100029

Graphical abstract: The MWCNT/Ni-B catalyst has been successfully prepared by an electroless deposition process. The Ni-B nanoparticles on the supporter are amorphous and are well-distributed. The catalytic conversion towards hydrogenation of styrene shows excellent catalytic activity of the obtained materials. Highlights: Black-Right-Pointing-Pointer A two-step treatment of MWCNTs enabled the homogeneous growth of Ni-B nanoparticles. Black-Right-Pointing-Pointer Ni-B nanoparticles were amorphous with an average size of 60 nm. Black-Right-Pointing-Pointer There were electron transfer between Ni and B. Black-Right-Pointing-Pointer The catalyst had excellent catalytic activity towards hydrogenation of styrene. -- Abstract: Nickel-boron (Ni-B) nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were successfully synthesizedmore » through an electroless deposition process using the plating bath with sodium borohydride as a reducing agent. The structural and morphological analyses using field-emission scanning electron microscopy, X-ray diffractometry and high-resolution transmission electron microscopy have shown that the Ni-B nanoparticles deposited on the sidewalls of MWCNTs are fine spheres comprised of amorphous structure with the morphologically unique fine-structure like flowers, and homogenously dispersed with a narrow particle size distribution centered at around 60 nm diameter. The catalytic activity of MWCNT/Ni-B nanoparticles was evaluated with respect to hydrogenation of styrene. The hydrogenation catalyzed by MWCNT-supported Ni-B nanoparticles has been found to make styrene selectively converted into ethylbenzene. The highest conversion reaches 99.8% under proper reaction conditions, which demonstrates the high catalytic activity of MWCNT/Ni-B nanoparticles.« less

Upgrading pyrolytic residue from waste tires to commercial carbon black.

PubMed

Zhang, Xue; Li, Hengxiang; Cao, Qing; Jin, Li'e; Wang, Fumeng

2018-05-01

The managing and recycling of waste tires has become a worldwide environmental challenge. Among the different disposal methods for waste tires, pyrolysis is regarded as a promising route. How to effectively enhance the added value of pyrolytic residue (PR) from waste tires is a matter of great concern. In this study, the PRs were treated with hydrochloric and hydrofluoric acids in turn under ultrasonic waves. The removal efficiency for the ash and sulfur was investigated. The pyrolytic carbon black (PCB) obtained after treating PR with acids was analyzed by X-ray fluorescence spectrophotometry, Fourier transform infrared spectrometry, X-ray diffractometry, laser Raman spectrometry, scanning electron microscopy, thermogravimetric (TG) analysis, and physisorption apparatus. The properties of PCB were compared with those of commercial carbon black (CCB) N326 and N339. Results showed PRs from waste tires were mainly composed of carbon, sulfur, and ash. The carbon in PCB was mainly from the CCB added during tire manufacture rather than from the pyrolysis of pure rubbers. The removal percentages for the ash and sulfur of PR are 98.33% (from 13.98 wt % down to 0.24 wt %) and 70.16% (from 1.81 wt % down to 0.54 wt %), respectively, in the entire process. The ash was mainly composed of metal oxides, sulfides, and silica. The surface properties, porosity, and morphology of the PCB were all close to those of N326. Therefore, PCB will be a potential alternative of N326 and reused in tire manufacture. This route successfully upgrades PR from waste tires to the high value-added CCB and greatly increases the overall efficiency of the waste tire pyrolysis industry.

First Evidence of Epithermal Gold Occurrences in the SE Afar Rift, Republic of Djibouti

NASA Astrophysics Data System (ADS)

Moussa, Nima; Fouquet, Yves; Caminiti, Antoine Marie; Le Gall, Bernard; Rolet, Joel; Bohn, Marcel; Etoubleau, Joel; Delacourt, Christophe; Jalludin, Mohamed

2010-05-01

The Republic of Djibouti, located at the SE part of the Afar volcanic Triangle, is characterized by intense tectonic and bimodal volcanic activity, and is emplaced over an earlier magmatic rift system, as old as 25-30 Ma. Each magmatic event is accompanied by hydrothermal activity. Few works have been so far published on hydrothermal mineralization in the Afar area. Mineralization generally occur as veins and are mainly associated with acidic volcanic intrusions along the fractures at the edges of grabens established during the last 4 Ma. Eighty samples from hydrothermal quartz ± carbonate veins and breccias were studied on 9 different sites representative of 4 main volcanic events ranging in age from early Miocene up to Present. Gold was found in excess of 200 ppb in 30% of the samples. Mineralogical analyses based on optical reflected light microscopy, X-Ray diffractometry, X-Ray fluorescence, inductively coupled plasma mass spectroscopy and electron microprobe, led us to identify two types of gold mineralization (i) native gold, electrum, hessite and sulfides (chalcopyrite, pyrite, bornite, ± sphalerite, and galena) in massive quartz breccias and banded chalcedony, (ii) gold, electrum, hematite, magnetite, trace minerals (argentite) and adularia in banded chalcedony. Another group without gold is characterized by quartz, pyrite ± goethite. Secondary minerals are characterized by goethite, native silver and native copper. Arsenic is enriched in pyrite in samples with a high gold content. The bimodal volcanism, the occurrence of adularia, the native gold and electrum in banded silica veins, are classically observed in neutral epithermal systems. The discovery of this type of mineralization in a recent-active continental rift system supplies new insights about hydrothermal processes associated with volcanic activity in a spreading context. Keywords: Republic of Djibouti, Afar Triangle, Hydrothermal, Epithermal system, Gold

Electronic, optical and photocatalytic behavior of Mn, N doped and co-doped TiO{sub 2}: Experiment and simulation

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

Zhao, Ya Fei; Li, Can, E-mail: canli1983@gmail.com; Lu, Song

2016-03-15

The crystal phase structure, surface morphology, chemical states and optical properties of Mn, N mono-doped and co-doped TiO{sub 2} nanoparticles were investigated by X-ray powder diffractometry, Raman spectra, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. Meanwhile, geometry structures, formation energies, electronic and optical properties of all systems have been also analyzed by density functional theory. The results showed that the band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO{sub 2}. The number and themore » carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light. Especially, the photocatalytic activity of Mn-2N co-doped TiO{sub 2} beyond three-fold than that of pure TiO{sub 2} under visible-light. - Graphical abstract: The ILs formed by N-2p orbital in N single doped specimen lie above the VB, while the ILs formed by Mn-3d orbital in Mn single doped specimen appear below the CB. However, a large amount of ILs formed by N-2p orbital and Mn-3d orbital in N and Mn codoped specimens. The band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO{sub 2}. The number and the carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light.« less

The effect of metal cluster deposition route on structure and photocatalytic activity of mono- and bimetallic nanoparticles supported on TiO2 by radiolytic method

NASA Astrophysics Data System (ADS)

Klein, Marek; Nadolna, Joanna; Gołąbiewska, Anna; Mazierski, Paweł; Klimczuk, Tomasz; Remita, Hynd; Zaleska-Medynska, Adriana

2016-08-01

TiO2 (P25) was modified with small and relatively monodisperse mono- and bimetallic clusters (Ag, Pd, Pt, Ag/Pd, Ag/Pt and Pd/Pt) induced by radiolysis to improve its photocatalytic activity. The as-prepared samples were characterized by X-ray fluorescence spectrometry (XRF), photoluminescence spectrometry (PL), diffuse reflectance spectroscopy (DRS), X-ray powder diffractometry (XRD), scanning transition electron microscopy (STEM) and BET surface area analysis. The effect of metal type (mono- and bimetallic modification) as well as deposition method (simultaneous or subsequent deposition of two metals) on the photocatalytic activity in toluene removal in gas phase under UV-vis irradiation (light-emitting diodes- LEDs) and phenol degradation in liquid phase under visible light irradiation (λ > 420 nm) were investigated. The highest photoactivity under Vis light was observed for TiO2 co-loaded with platinum (0.1%) and palladium (0.1%) clusters. Simultaneous addition of metal precursors results in formation of larger metal nanoparticles (15-30 nm) on TiO2 surface and enhances the Vis-induced activity of Ag/Pd-TiO2 up to four times, while the subsequent metal ions addition results in formation of metal particle size ranging from 4 to 20 nm. Subsequent addition of metal precursors results in formation of BNPs (bimetallic nanoparticle) composites showing higher stability in four cycles of toluene degradation under UV-vis. Obtained results indicated that direct electron transfer from the BNPs to the conduction band of the semiconductor is responsible for visible light photoactivity, whereas superoxide radicals (such as O2rad- and rad OOH) are responsible for pollutants degradation over metal-TiO2 composites.

Engineering solar cells based on correlative X-ray microscopy

DOE PAGES

Stuckelberger, Michael; West, Bradley; Nietzold, Tara; ...

2017-05-01

In situ and operando measurement techniques combined with nanoscale resolution have proven invaluable in multiple fields of study. We argue that evaluating device performance as well as material behavior by correlative X-ray microscopy with <100 nm resolution can radically change the approach for optimizing absorbers, interfaces and full devices in solar cell research. Here, we thoroughly discuss the measurement technique of X-ray beam induced current and point out fundamental differences between measurements of wafer-based silicon and thin-film solar cells. Based on reports of the last years, we showcase the potential that X-ray microscopy measurements have in combination with in situmore » and operando approaches throughout the solar cell lifecycle: from the growth of individual layers to the performance under operating conditions and degradation mechanisms. Enabled by new developments in synchrotron beamlines, the combination of high spatial resolution with high brilliance and a safe working distance allows for the insertion of measurement equipment that can pave the way for a new class of experiments. When applied to photovoltaics research, we highlight today’s opportunities and challenges in the field of nanoscale X-ray microscopy, and give an outlook on future developments.« less

The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy.

PubMed

Chen, Jun; Lan, Xiangna; Wang, Chao; Zhang, Qinyong

2018-03-08

Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO₄·3H₂O, MnHPO₄·2.25H₂O, BaHPO₄·3H₂O, BaMg₂(PO₄)₂, Mg₃(PO₄)₂·22H₂O, Ca₃(PO₄)₂·xH₂O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl.

Reversible Li storage for nanosize cation/anion-disordered rocksalt-type oxyfluorides: LiMoO2 - x LiF (0 ≤ x ≤ 2) binary system

NASA Astrophysics Data System (ADS)

Takeda, Nanami; Hoshino, Satoshi; Xie, Lixin; Chen, Shuo; Ikeuchi, Issei; Natsui, Ryuichi; Nakura, Kensuke; Yabuuchi, Naoaki

2017-11-01

A binary system of LiMoO2 - x LiF (0 ≤ x ≤ 2), Li1+xMoO2Fx, is systematically studied as potential positive electrode materials for rechargeable Li batteries. Single phase and nanosized samples on this binary system are successfully prepared by using a mechanical milling route. Crystal structures and Li storage properties on the binary system are also examined. Li2MoO2F (x = 1), which is classified as a cation-/anion-disordered rocksalt-type structure and is a thermodynamically metastable phase, delivers a large reversible capacity of over 300 mAh g-1 in Li cells with good reversibility. Highly reversible Li storage is realized for Li2MoO2F consisting of nanosized particles based on Mo3+/Mo5+ two-electron redox as evidenced by ex-situ X-ray absorption spectroscopy coupled with ex-situ X-ray diffractometry. Moreover, the presence of the most electronegative element in the framework structure effectively increases the electrode potential of Mo redox through an inductive effect. From these results, potential of nanosized lithium molybdenum oxyfluorides for high-capacity positive electrode materials of rechargeable Li batteries are discussed.

Methods of chemical and phase composition analysis of gallstones

NASA Astrophysics Data System (ADS)

Suvorova, E. I.; Pantushev, V. V.; Voloshin, A. E.

2017-11-01

This review presents the instrumental methods used for chemical and phase composition investigation of gallstones. A great body of data has been collected in the literature on the presence of elements and their concentrations, obtained by fluorescence microscopy, X-ray fluorescence spectroscopy, neutron activation analysis, proton (particle) induced X-ray emission, atomic absorption spectroscopy, high-resolution gamma-ray spectrometry, electron paramagnetic resonance. Structural methods—powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy—provide information about organic and inorganic phases in gallstones. Stone morphology was studied at the macrolevel with optical microscopy. Results obtained by analytical scanning and transmission electron microscopy with X-ray energy dispersive spectrometry are discussed. The chemical composition and structure of gallstones determine the strategy of removing stone from the body and treatment of patients: surgery or dissolution in the body. Therefore one chapter of the review describes the potential of dissolution methods. Early diagnosis and appropriate treatment of the disease depend on the development of clinical methods for in vivo investigation, which gave grounds to present the main characteristics and potential of ultrasonography (ultrasound scanning), magnetic resonance imaging, and X-ray computed tomography.

Biological imaging by soft x-ray diffraction microscopy

DOE PAGES

Shapiro, D.; Thibault, P.; Beetz, T.; ...

2005-10-25

We have used the method of x-ray diffraction microscopy to image the complex-valued exit wave of an intact and unstained yeast cell. The images of the freeze-dried cell, obtained by using 750-eV x-rays from different angular orientations, portray several of the cell's major internal components to 30-nm resolution. The good agreement among the independently recovered structures demonstrates the accuracy of the imaging technique. To obtain the best possible reconstructions, we have implemented procedures for handling noisy and incomplete diffraction data, and we propose a method for determining the reconstructed resolution. This work represents a previously uncharacterized application of x-ray diffractionmore » microscopy to a specimen of this complexity and provides confidence in the feasibility of the ultimate goal of imaging biological specimens at 10-nm resolution in three dimensions.« less

Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research

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

Moffet, Ryan C.; Tivanski, Alexei V.; Gilles, Mary K.

Scanning transmission x-ray microscopy (STXM) combines x-ray microscopy and near edge x-ray absorption fine structure spectroscopy (NEXAFS). This combination provides spatially resolved bonding and oxidation state information. While there are reviews relevant to STXM/NEXAFS applications in other environmental fields (and magnetic materials) this chapter focuses on atmospheric aerosols. It provides an introduction to this technique in a manner approachable to non-experts. It begins with relevant background information on synchrotron radiation sources and a description of NEXAFS spectroscopy. The bulk of the chapter provides a survey of STXM/NEXAFS aerosol studies and is organized according to the type of aerosol investigated. Themore » purpose is to illustrate the current range and recent growth of scientific investigations employing STXM-NEXAFS to probe atmospheric aerosol morphology, surface coatings, mixing states, and atmospheric processing.« less

Hydration reactivity of crystalline and vitrified diopside under hydrothermal conditions

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

Grzeszczyk, S.; Szuba, J.

1990-07-01

Hydration reactivity of diopside in both the crystalline and amorphous (glassy) phase was studied under hydrothermal conditions. Samples were treated in an autoclave at 200{degrees}C in saturated vapor for 24 and 72 h. The progress of hydration was determined by X-ray powder diffractometry and IR spectroscopy. Results indicate that crystalline diopside possessed poor hydraulic activity. However, once vitrified it proved to be much more reactive. The principal hydration products found for the glassy diopside after 24 and 72 h of treatment were calcium silicate hydrate (xonotlite) and magnesium silicate hydrates (chrysotile and tremolite).

Functionalization of 2D macroporous silicon under the high-pressure oxidation

NASA Astrophysics Data System (ADS)

Karachevtseva, L.; Kartel, M.; Kladko, V.; Gudymenko, O.; Bo, Wang; Bratus, V.; Lytvynenko, O.; Onyshchenko, V.; Stronska, O.

2018-03-01

Addition functionalization after high-pressure oxidation of 2D macroporous silicon structures is evaluated. X-ray diffractometry indicates formation of orthorhombic SiO2 phase on macroporous silicon at oxide thickness of 800-1200 nm due to cylindrical symmetry of macropores and high thermal expansion coefficient of SiO2. Pb center concentration grows with the splitting energy of LO- and TO-phonons and SiO2 thickness in oxidized macroporous silicon structures. This increase EPR signal amplitude and GHz radiation absorption and is promising for development of high-frequency devices and electronically controlled elements.

Structural and mechanical behaviour of LLDPE/HNT nanocomposite films

NASA Astrophysics Data System (ADS)

Čermák, M.; Kadlec, P.; Šutta, P.; Polanský, R.

2016-03-01

The paper briefly describes structural and mechanical influences of Halloysite nanotubes (HNT) in different level of fulfilment (0, 1, 3, 7 wt%) in the LLDPE commonly used in the cable industry. The influence of HNT on the polymer has been observed and evaluated through the average crystallite size and the micro- deformation by X-Ray diffractometry and the imaging of SEM. Despite the certain inter-phase tension between the polymer and HNT, the influence on the mechanical and combustion behaviour was observed. Measurement showed a higher content of agglomerates in the sample with 7 wt% HNT fulfilment.

3D nanoscale imaging of biological samples with laboratory-based soft X-ray sources

NASA Astrophysics Data System (ADS)

Dehlinger, Aurélie; Blechschmidt, Anne; Grötzsch, Daniel; Jung, Robert; Kanngießer, Birgit; Seim, Christian; Stiel, Holger

2015-09-01

In microscopy, where the theoretical resolution limit depends on the wavelength of the probing light, radiation in the soft X-ray regime can be used to analyze samples that cannot be resolved with visible light microscopes. In the case of soft X-ray microscopy in the water-window, the energy range of the radiation lies between the absorption edges of carbon (at 284 eV, 4.36 nm) and oxygen (543 eV, 2.34 nm). As a result, carbon-based structures, such as biological samples, posses a strong absorption, whereas e.g. water is more transparent to this radiation. Microscopy in the water-window, therefore, allows the structural investigation of aqueous samples with resolutions of a few tens of nanometers and a penetration depth of up to 10μm. The development of highly brilliant laser-produced plasma-sources has enabled the transfer of Xray microscopy, that was formerly bound to synchrotron sources, to the laboratory, which opens the access of this method to a broader scientific community. The Laboratory Transmission X-ray Microscope at the Berlin Laboratory for innovative X-ray technologies (BLiX) runs with a laser produced nitrogen plasma that emits radiation in the soft X-ray regime. The mentioned high penetration depth can be exploited to analyze biological samples in their natural state and with several projection angles. The obtained tomogram is the key to a more precise and global analysis of samples originating from various fields of life science.

3-D Cellular Ultrastructure Can Be Resolved by X-ray Microscopy | Center for Cancer Research

Cancer.gov

X-ray microscopy (XRM) is more rapid than cryoelectron tomography or super-resolution fluorescence microscopy and could fill an important gap in current technologies used to investigate in situ three-dimensional structure of cells. New XRM methods developed by first author Gerd Schneider, Ph.D., working with James McNally. Ph.D., and a team of colleagues, is capable of

The X-ray microscopy beamline UE46-PGM2 at BESSY

NASA Astrophysics Data System (ADS)

Follath, R.; Schmidt, J. S.; Weigand, M.; Fauth, K.

2010-06-01

The Max Planck Institute for Metal Physics in Stuttgart and the Helmholtz Center Berlin operate a soft X-ray microscopy beamline at the storage ring BESSY II. A collimated PGM serves as monochromator for a scanning X-ray microscope and a full field X-ray microscope at the helical undulator UE46. The selection between both instruments is accomplished via two switchable focusing mirrors. The scanning microscope (SM) is based on the ALS STXM microscope and fabricated by the ACCEL company. The full field microscope (FFM) is currently in operation at the U41-SGM beamline and will be relocated to its final location this year.

X-ray Full Field Microscopy at 30 keV

NASA Astrophysics Data System (ADS)

Marschall, F.; Last, A.; Simon, M.; Kluge, M.; Nazmov, V.; Vogt, H.; Ogurreck, M.; Greving, I.; Mohr, J.

2014-04-01

In our X-ray full field microscopy experiments, we demonstrated a resolution better than 260 nm over the entire field of view of 80 μm × 80 μm at 30 keV. Our experimental setup at PETRA III, P05, had a length of about 5 m consisting of an illumination optics, an imaging lens and a detector. For imaging, we used a compound refractive lens (CLR) consisting of mr-L negative photo resist, which was fabricated by deep X-ray lithography. As illumination optics, we choose a refractive rolled X-ray prism lens, which was adapted to the numerical aperture of the imaging lens.

Recent progress of hard x-ray imaging microscopy and microtomography at BL37XU of SPring-8

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

Suzuki, Yoshio, E-mail: yoshio@spring8.or.jp; Takeuchi, Akihisa; Terada, Yasuko

2016-01-28

A hard x-ray imaging microscopy and microtomography system is now being developed at the beamline 37XU of SPring-8. In the latest improvement, a spatial resolution of about 50 nm is achieved in two-dimensional imaging at 6 keV x-ray energy using a Fresnel zone plate objective with an outermost zone width of 35 nm. In the tomographic measurement, a spatial resolution of about 100 nm is achieved at 8 keV using an x-ray guide tube condenser optic and a Fresnel zone plate objective with an outermost zone width of 50 nm.

Structural and elemental changes in glioblastoma cells in situ: complementary imaging with high resolution visible light- and X-ray microscopy

DOE PAGES

Ducic, Tanja; Paunesku, Tatjana; Chen, Si; ...

2016-12-09

The glioblastoma (GBM) is characterized by a short median survival and an almost 100% tumor related mortality. GBM cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores application of X-ray and visible light microscopy to display the elemental and structural images of cells from 3 patient derived GMB samples and an established GMB cell line. Slight differences in elemental concentrations, in actin cytoskeleton organization and cell morphology were noted between all cells types by X-ray fluorescence and full field soft X-ray microscopy, as well as the Structured Illumination Super-resolution Microscope (SIM). Different samplemore » preparation approaches were used to match each imaging technique. While preparation for SIM included cell fixation and staining, intact frozen hydrated cells were used for the trace element imaging by hard X-ray fluorescence and exploration of the structural features by soft X-ray absorption tomography. In conclusion, each technique documented differences between samples with regard to morphology and elemental composition and underscored the importance of use of multiple patient derived samples for detailed GBM study.« less

Structural and elemental changes in glioblastoma cells in situ: complementary imaging with high resolution visible light- and X-ray microscopy

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

Ducic, Tanja; Paunesku, Tatjana; Chen, Si

The glioblastoma (GBM) is characterized by a short median survival and an almost 100% tumor related mortality. GBM cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores application of X-ray and visible light microscopy to display the elemental and structural images of cells from 3 patient derived GMB samples and an established GMB cell line. Slight differences in elemental concentrations, in actin cytoskeleton organization and cell morphology were noted between all cells types by X-ray fluorescence and full field soft X-ray microscopy, as well as the Structured Illumination Super-resolution Microscope (SIM). Different samplemore » preparation approaches were used to match each imaging technique. While preparation for SIM included cell fixation and staining, intact frozen hydrated cells were used for the trace element imaging by hard X-ray fluorescence and exploration of the structural features by soft X-ray absorption tomography. In conclusion, each technique documented differences between samples with regard to morphology and elemental composition and underscored the importance of use of multiple patient derived samples for detailed GBM study.« less

Hard X-ray-induced damage on carbon–binder matrix for in situ synchrotron transmission X-ray microscopy tomography of Li-ion batteries

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

Lim, Cheolwoong; Kang, Huixiao; De Andrade, Vincent

2017-03-21

The electrode of Li-ion batteries is required to be chemically and mechanically stable in the electrolyte environment forin situmonitoring by transmission X-ray microscopy (TXM). Evidence has shown that continuous irradiation has an impact on the microstructure and the electrochemical performance of the electrode. To identify the root cause of the radiation damage, a wire-shaped electrode is soaked in an electrolyte in a quartz capillary and monitored using TXM under hard X-ray illumination. The results show that expansion of the carbon–binder matrix by the accumulated X-ray dose is the key factor of radiation damage. Forin situTXM tomography, intermittent X-ray exposure duringmore » image capturing can be used to avoid the morphology change caused by radiation damage on the carbon–binder matrix.« less

Preparation and Thermoelectric Properties of IR(sub x)Co(sub 1-x)Sb(sub 2) Alloys

NASA Technical Reports Server (NTRS)

Caillat, Thierry

1995-01-01

The preparation and characterization of the binary arsenopyrite compounds CoSb2 and IrSb2 and IrxCo1-xSb2 alloys is reported. Single crystals of CoSb2 were grown by the vertical gradient freeze technique from solution rich in antimony. Polycrystalline samples of IrSb2 and IrxCo1-xSb2 alloys were prepared by hot-pressing of prereacted elemental powders. Samples were investigated by X-ray diffractometry, microprobe analysis and density measurements. It was found that a range of solid solution exist in the system IrxCo1-xSb2 for 0.1

Self-assembled flower-like antimony trioxide microstructures with high infrared reflectance performance

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

Ge, Shengsong, E-mail: geshengsong@126.com; Yang, Xiaokun; Shao, Qian

A simple hydrothermal process was adopted to self-assembly prepare high infrared reflective antimony trioxide with three-dimensional flower-like microstructures. The morphologies of antimony trioxide microstructures were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM) respectively. It is also found that experimental parameters, such as NaOH concentration, surfactant concentration and volume ratio of ethanol–water played crucial roles in controlling the morphologies of Sb{sub 2}O{sub 3} microstructures. A possible growth mechanism of flower-like Sb{sub 2}O{sub 3} microstructure was proposed based on the experimental data. UV–vis–NIR spectra verified that the near infraredmore » reflectivity of the obtained flower-like microstructures could averagely achieve as 92% with maximum reflectivity of 98%, obviously higher than that of other different morphologies of antimony trioxide microstructures. It is expected that the flower-like Sb{sub 2}O{sub 3} nanostructures have some applications in optical materials and heat insulation coatings. - Graphical abstract: Flower-like Sb{sub 2}O{sub 3} microstructures that composed of nanosheets with thickness of ca. 100 nm exhibit high reflectivity under UV–vis–NIR spectra. Highlights: ► Uniform flower-like microstructures were synthesized via simple hydrothermal reaction. ► The flower-like Sb{sub 2}O{sub 3} microstructures exhibited higher reflectivity than other morphologies under the UV–vis–NIR light. ► Influencing parameters on the Sb{sub 2}O{sub 3} morphologies have been discussed in detail. ► Possible mechanism leading to flower-like microstructures was proposed.« less

3D X-ray ultra-microscopy of bone tissue.

PubMed

Langer, M; Peyrin, F

2016-02-01

We review the current X-ray techniques with 3D imaging capability at the nano-scale: transmission X-ray microscopy, ptychography and in-line phase nano-tomography. We further review the different ultra-structural features that have so far been resolved: the lacuno-canalicular network, collagen orientation, nano-scale mineralization and their use as basis for mechanical simulations. X-ray computed tomography at the micro-metric scale is increasingly considered as the reference technique in imaging of bone micro-structure. The trend has been to push towards increasingly higher resolution. Due to the difficulty of realizing optics in the hard X-ray regime, the magnification has mainly been due to the use of visible light optics and indirect detection of the X-rays, which limits the attainable resolution with respect to the wavelength of the visible light used in detection. Recent developments in X-ray optics and instrumentation have allowed to implement several types of methods that achieve imaging that is limited in resolution by the X-ray wavelength, thus enabling computed tomography at the nano-scale. We review here the X-ray techniques with 3D imaging capability at the nano-scale: transmission X-ray microscopy, ptychography and in-line phase nano-tomography. Further, we review the different ultra-structural features that have so far been resolved and the applications that have been reported: imaging of the lacuno-canalicular network, direct analysis of collagen orientation, analysis of mineralization on the nano-scale and use of 3D images at the nano-scale to drive mechanical simulations. Finally, we discuss the issue of going beyond qualitative description to quantification of ultra-structural features.

Synthesis of samarium doped gadolinium oxide nanorods, its spectroscopic and physical properties

NASA Astrophysics Data System (ADS)

Boopathi, G.; Gokul Raj, S.; Ramesh Kumar, G.; Mohan, R.; Mohan, S.

2018-06-01

One-dimensional samarium doped gadolinium oxide [Sm:Gd2O3] nanorods have been synthesized successfully through co-precipitation technique in aqueous solution. The as-synthesized and calcined products were characterized by using powder X-ray diffraction pattern, Fourier transform Raman spectroscopy, thermogravimetric/differential thermal analysis, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, Ultraviolet-Visible spectrometry, photoluminescence spectrophotometer and X-ray photoelectron spectroscopy techniques. The obtained results are discussed in detailed manner.

Intracellular distribution and stability of a luminescent rhenium(i) tricarbonyl tetrazolato complex using epifluorescence microscopy in conjunction with X-ray fluorescence imaging.

PubMed

Wedding, J L; Harris, H H; Bader, C A; Plush, S E; Mak, R; Massi, M; Brooks, D A; Lai, B; Vogt, S; Werrett, M V; Simpson, P V; Skelton, B W; Stagni, S

2017-04-19

Optical epifluorescence microscopy was used in conjunction with X-ray fluorescence imaging to monitor the stability and intracellular distribution of the luminescent rhenium(i) complex fac-[Re(CO) 3 (phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence imaging techniques. X-ray fluorescence also showed that the rhenium complex disrupted the homeostasis of some biologically relevant elements, such as chlorine, potassium and zinc.

X-ray microscopy using reflection targets based on SEM with tungsten filament

NASA Astrophysics Data System (ADS)

Liu, Junbiao; Ma, Yutian; Zhao, Weixia; Niu, Geng; Chu, Mingzhang; Yin, Bohua; Han, Li; Liu, Baodong

2016-10-01

X-ray MicroandNano imaging is developed based on the conventional x-ray tomography, it can not only provide nondestructive testing with higher resolution measurement, but also be used to examine the material or the structure with low atomic number and low density. The source with micro-focal spot size is one of the key components of x-ray MicroandNano imaging. The focused electron beam from SEM bombarding the metal target can generate x-ray with ultra-small size. It is convenient to set up x-ray microscopy based on SEM for laboratory use. This paper describes a new x-ray microscopy using reflection targets based on FEI Quanta600 SEM with tungsten filament. The flat panel detector is placed outside of the vacuum chamber with 300μm thickness Be-window to isolate vacuum from the air. A stage with 3 DOFs is added to adjust the positions of the target, the SEM's sample stage is used to move sample. And the shape of target is designed as cone with 60° half cone angle to get the maximum x-ray dosage. The attenuation coefficient of Bewindow for x-ray is about 25%. Finally, the line pair card is used to evaluate the resolution and the result shows that the resolution of the system can receive less than 750nm, when the acceleration voltage is 30keV, the beam current is 160nA, the SEM working distance is 5mm and the acquisition time of the detector is 60s.

Synthesis and Characterization of Cu- and Co-Doped Bi4V2O11 for Intermediate-Temperature Solid Oxide Fuel Cell Electrolytes by Carbonate Coprecipitation

NASA Astrophysics Data System (ADS)

Lee, Jin Goo; Yoon, Hyon Hee

2011-01-01

Bi2MexV1-xO5.5-3x/2 (Me = Cu; 0≤x≤0.2) powders were prepared by the ammonium carbonate coprecipitation method. The starting salts were bismuth nitrate, copper nitrate, cobalt nitrate, and vanadium sulphate. The thermal decomposition of Bi2MexV1-xO5.5-3x/2 precursors was completed at about 500 °C. The crystallite structure, surface morphology, and ionic conductivity of the prepared powders and pellets were examined using X-ray diffractometry, field emission scanning electron microscopy, and an impedance analyzer, respectively. The average particle sizes of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 powders were 10-50 nm. The tetragonal structure (γ-phase) appeared at sintering temperatures higher than 700 °C and the peak intensity increased at higher sintering temperatures. The ionic conductivities of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 pellets sintered at 800 °C showed the highest values of 6.8×10-2 S cm-1 at 700 °C and 9.1×10-2 S cm-1 at 700 °C, respectively. The optimum concentration of the Cu and Co dopants in Bi2MexV1-xO5.5-3x/2 was determined to be 0.1. The results of this study demonstrated that the ammonium carbonate coprecipitation process could be used as an economical method for the preparation of Bi2MexV1-xO5.5-3x/2 electrolytes for intermediate-temperature solid oxide fuel cells.

Growth of single crystals of mercuric iodide (HgI/sub 2/) in spacelab III

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

Van Den Berg, L.; Schnepple, W.F.

1981-01-01

Continued development of a system designed to grow crystals by physical vapor transport in the environment of Spacelab III will be described, with special emphasis on simulation of expected space conditions, adjustment of crystal growth parameters, and on board observation and control of the experiment by crew members and ground personnel. A critical factor in the use of mercuric iodide for semiconductor detectors of x-rays and gamma-rays is the crystalline quality of the material. The twofold purpose of the Spacelab III experiment is therefore to grow single crystals with superior electronic properties as an indirect result of the greatly reducedmore » gravity field during the growth, and to obtain data which will lead to improved understanding of the vapor transport mechanism. The experiments planned to evaluate the space crystals, including gamma-ray diffractometry and measurements of stoichiometry, lattice dimensions, mechanical strength, luminescense, and detector performance are discussed.« less

Doped Lanthanum Hafnates as Scintillating Materials for High-Energy Photon Detection

NASA Astrophysics Data System (ADS)

Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing

Recent years have seen the emergence of nanocrystalline complex oxide scintillators for use in X-ray and gamma-ray detection. In this study, we investigate the structural and optical properties of La2Hf2O7 nanoparticles doped with varying levels of Eu3+ or Ce3+ by use of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and optical photoluminescence. In addition, scintillation response under X-ray and gamma-ray exposure is reported. The authors thank the support from the Defense Threat Reduction Agency (DTRA) of the U.S. Department of Defense (Award #HDTRA1-10-1-0114).

Estimation of Crystallinity of Nifedipine-Polyvinylpyrrolidone Solid Dispersion by Usage of Terahertz Time-Domain Spectroscopy and of X-Ray Powder Diffractometer.

PubMed

Takeuchi, Issei; Shimakura, Kemmaro; Kuroda, Hideki; Nakajima, Takehisa; Goto, Satoru; Makino, Kimiko

2015-12-01

Crystalline state of pharmaceutical materials is of great importance in preparation of pharmaceutics, because their physicochemical properties affect bioavailability, quality of products, therapeutic level and manufacturing process. In this study, we have estimated time-dependent changes of nifedipine in nifedipine-polyvinylpyrrolidone (PVP) solid dispersion by measuring terahertz time-domain spectroscopy (THz-TDS) and by X-ray powder diffractometry (XRPD), and compared their correlativity. Crystallinity of nifedipine-PVP solid dispersion was changed by storing the amorphous sample at 25°C-75°C and relative humidity of over 80% for 0.25-24.00 h. To compare the results of two types of measurements, we have used a general method of linear regression analysis. Crystallinities estimated using THz-TDS were plotted on the x-axis and that of XRPD were on the y-axis. From the result of the calculation, the correlativity of them was confirmed. THz-TDS has the capability of becoming the replacement of XRPD. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

High spatial resolution soft-x-ray microscopy

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

Meyer-Ilse, W.; Medecki, H.; Brown, J.T.

1997-04-01

A new soft x-ray microscope (XM-1) with high spatial resolution has been constructed by the Center for X-ray Optics. It uses bending magnet radiation from beamline 6.1 at the Advanced Light Source, and is used in a variety of projects and applications in the life and physical sciences. Most of these projects are ongoing. The instrument uses zone plate lenses and achieves a resolution of 43 nm, measured over 10% to 90% intensity with a knife edge test sample. X-ray microscopy permits the imaging of relatively thick samples, up to 10 {mu}m thick, in water. XM-1 has an easy tomore » use interface, that utilizes visible light microscopy to precisely position and focus the specimen. The authors describe applications of this device in the biological sciences, as well as in studying industrial applications including structured polymer samples.« less

3D nanoscale imaging of the yeast, Schizosaccharomyces pombe, by full-field transmission X-ray microscopy at 5.4 keV.

PubMed

Chen, Jie; Yang, Yunhao; Zhang, Xiaobo; Andrews, Joy C; Pianetta, Piero; Guan, Yong; Liu, Gang; Xiong, Ying; Wu, Ziyu; Tian, Yangchao

2010-07-01

Three-dimensional (3D) nanoscale structures of the fission yeast, Schizosaccharomyces pombe, can be obtained by full-field transmission hard X-ray microscopy with 30 nm resolution using synchrotron radiation sources. Sample preparation is relatively simple and the samples are portable across various imaging environments, allowing for high-throughput sample screening. The yeast cells were fixed and double-stained with Reynold's lead citrate and uranyl acetate. We performed both absorption contrast and Zernike phase contrast imaging on these cells in order to test this method. The membranes, nucleus, and subcellular organelles of the cells were clearly visualized using absorption contrast mode. The X-ray images of the cells could be used to study the spatial distributions of the organelles in the cells. These results show unique structural information, demonstrating that hard X-ray microscopy is a complementary method for imaging and analyzing biological samples.

Well-aligned polycrystalline lanthanum silicate oxyapatite grown by reactive diffusion between solid La{sub 2}SiO{sub 5} and gases [SiO+1/2O{sub 2}

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

Fukuda, Koichiro, E-mail: fukuda.koichiro@nitech.ac.jp; Hasegawa, Ryo; Kitagawa, Takuya

2016-03-15

The c-axis-oriented polycrystalline lanthanum silicate oxyapatite, La{sub 9.48}(Si{sub 5.89}□{sub 0.11})O{sub 26} (□ denotes a vacancy in the Si site), was successfully prepared by the reactive diffusion between randomly grain-oriented La{sub 2}SiO{sub 5} polycrystal and [SiO+1/2O{sub 2}] gases at 1873 K in Ar atmosphere. The polycrystal was characterized using optical microscopy, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, micro-Raman spectroscopy, X-ray diffractometry, and impedance spectroscopy. The crystal structure (space group P6{sub 3}/m) showed the deficiency of Si site at ca. 1.9%. The bulk oxide-ion conductivity along the grain-alignment direction steadily increased from 9.2 × 10{sup −3} to 1.17 ×more » 10{sup −2} S/cm with increasing temperature from 923 to 1073 K. The activation energy of conduction was 0.23(2) eV. - Graphical abstract: We have successfully prepared the highly c-axis-oriented polycrystalline La{sub 9.48}(Si{sub 5.89}□{sub 0.11})O{sub 26} by the reactive diffusion between randomly grain-oriented La{sub 2}SiO{sub 5} polycrystal and [SiO + 1/2O{sub 2}] gases at 1873 K in Ar atmosphere. The crystal structure (space group P6{sub 3}/m) showed the deficiency of Si site of ca. 1.9%. - Highlights: • The c-axis-oriented polycrystalline La{sub 9.48}(Si{sub 5.89}□{sub 0.11})O{sub 26} is successfully prepared. • Crystal structure of La{sub 9.48}(Si{sub 5.89}□{sub 0.11})O{sub 26} is determined by single-crystal XRD. • The polycrystal shows relatively high oxide ion conductivity along the common c-axis. • Reactive diffusion is successfully used for the preparation of grain-aligned ceramics.« less

Advancement of X-Ray Microscopy Technology and its Application to Metal Solidification Studies

NASA Technical Reports Server (NTRS)

Kaukler, William F.; Curreri, Peter A.

1996-01-01

The technique of x-ray projection microscopy is being used to view, in real time, the structures and dynamics of the solid-liquid interface during solidification. By employing a hard x-ray source with sub-micron dimensions, resolutions of 2 micrometers can be obtained with magnifications of over 800 X. Specimen growth conditions need to be optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. It turns out that no single imaging technology offers the best solution and traditional methods like radiographic film cannot be used due to specimen motion (solidification). In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast.

Electrochromic Properties of Tungsten Oxide Films Prepared by Reactive Sputtering

NASA Astrophysics Data System (ADS)

Kim, Min Hong; Kang, Tai Young; Jung, Yu Sup; Kim, Kyung Hwan

2013-05-01

WO3-x thin films were deposited on induim tin oxide (ITO) glass substrates with various oxygen flow ratios from 0.55 to 0.7 by the reactive facing-target sputtering method, at a power density of 4 W/cm2 and room temperature. The structural properties of the WO3-x thin films were measured by X-ray diffractometry and Raman spectral analysis. As-deposited WO3-x thin films had an amorphous structure. In the Raman spectra, WO3-x thin films exhibited two strong peaks at 770 and 950 cm-1 attributed to the vibrations of W6+-O and W6+=O bonds, respectively. The electrochemical and optical properties of WO3-x thin films were measured by cyclic voltammetry and UV/vis spectrometry. The results showed the highest charge density at an oxygen flow ratio of 0.7 and the highest transmittance in the visible range. The maximum coloration efficiency was 30.82 cm2/C at an oxygen flow ratio of 0.7.

Optical, Fluorescence with quantum analysis of hydrazine (1, 3- Dinitro Phenyl) by DFT and Ab initio approach

NASA Astrophysics Data System (ADS)

Cecily Mary Glory, D.; Sambathkumar, K.; Madivanane, R.; Velmurugan, G.; Gayathri, R.; Nithiyanantham, S.; Venkatachalapathy, M.; Rajkamal, N.

2018-07-01

Experimental and computational study of molecular structure, vibrational and UV-spectral analysis of Hydrazine (1, 3- Dinitrophenyl) (HDP) derivatives. The crystal was grown by slow cooling method and the crystalline perfection of single crystals was evaluated by high resolution X-ray diffractometry (HRXRD) using a multicrystal X-ray diffractometer. Fluorescence, FT-IR and FT-Raman spectra of HDP crystal were recorded. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) followed by scaled quantum force field methodology (SQMFF). NMR studies have confirmed respectively the crystal structure and functional groups of the grown crystal. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated MESP, UV, HOMO-LUMO energies show that charge transfer done within the molecule. And various thermodynamic parameters are studied. Fukui determines the local reactive site of electrophilic, nucleophilic, descriptor.

Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

NASA Astrophysics Data System (ADS)

Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

2018-02-01

A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

Microscopy of biological sample through advanced diffractive optics from visible to X-ray wavelength regime.

PubMed

Di Fabrizio, Enzo; Cojoc, Dan; Emiliani, Valentina; Cabrini, Stefano; Coppey-Moisan, Maite; Ferrari, Enrico; Garbin, Valeria; Altissimo, Matteo

2004-11-01

The aim of this report is to demonstrate a unified version of microscopy through the use of advanced diffractive optics. The unified scheme derives from the technical possibility of realizing front wave engineering in a wide range of electromagnetic spectrum. The unified treatment is realized through the design and nanofabrication of phase diffractive elements (PDE) through which wave front beam shaping is obtained. In particular, we will show applications, by using biological samples, ranging from micromanipulation using optical tweezers to X-ray differential interference contrast (DIC) microscopy combined with X-ray fluorescence. We report some details on the design and physical implementation of diffractive elements that besides focusing also perform other optical functions: beam splitting, beam intensity, and phase redistribution or mode conversion. Laser beam splitting is used for multiple trapping and independent manipulation of micro-beads surrounding a cell as an array of tweezers and for arraying and sorting microscopic size biological samples. Another application is the Gauss to Laguerre-Gauss mode conversion, which allows for trapping and transfering orbital angular momentum of light to micro-particles immersed in a fluid. These experiments are performed in an inverted optical microscope coupled with an infrared laser beam and a spatial light modulator for diffractive optics implementation. High-resolution optics, fabricated by means of e-beam lithography, are demonstrated to control the intensity and the phase of the sheared beams in x-ray DIC microscopy. DIC experiments with phase objects reveal a dramatic increase in image contrast compared to bright-field x-ray microscopy. Besides the topographic information, fluorescence allows detection of certain chemical elements (Cl, P, Sc, K) in the same setup, by changing the photon energy of the x-ray beam. (c) 2005 Wiley-Liss, Inc.

Amino Acid Interaction with and Adsorption on Clays: FT-IR and Mössbauer Spectroscopy and X-ray Diffractometry Investigations

NASA Astrophysics Data System (ADS)

Benetoli, Luís O. B.; de Souza, Cláudio M. D.; da Silva, Klébson L.; de Souza, Ivan G.; de Santana, Henrique; Paesano, Andrea; da Costa, Antonio C. S.; Zaia, Cássia Thaïs B. V.; Zaia, Dimas A. M.

2007-12-01

In the present paper, the adsorption of amino acids (Ala, Met, Gln, Cys, Asp, Lys, His) on clays (bentonite, kaolinite) was studied at different pH (3.00, 6.00, 8.00). The amino acids were dissolved in seawater, which contains the major elements. There were two main findings in this study. First, amino acids with a charged R group (Asp, Lys, His) and Cys were adsorbed on clays more than Ala, Met and Gln (uncharged R groups). However, 74% of the amino acids in the proteins of modern organisms have uncharged R groups. These results raise some questions about the role of minerals in providing a prebiotic concentration mechanism for amino acids. Several mechanisms are also discussed that could produce peptide with a greater proportion of amino acids with uncharged R groups. Second, Cys could play an important role in prebiotic chemistry besides participating in the structure of peptides/proteins. The FT-IR spectra showed that the adsorption of amino acids on the clays occurs through the amine group. However, the Cys/clay interaction occurs through the sulfhydryl and amine groups. X-ray diffractometry showed that pH affects the bentonite interlayer, and at pH 3.00 the expansion of Cys/bentonite was greater than that of the samples of ethylene glycol/bentonite saturated with Mg. The Mössbauer spectrum for the sample with absorbed Cys showed a large increase (˜20%) in ferrous ions. This means that Cys was able to partially reduce iron present in bentonite. This result is similar to that which occurs with aconitase where the ferric ions are reduced to Fe 2.5.

3D elemental sensitive imaging using transmission X-ray microscopy.

PubMed

Liu, Yijin; Meirer, Florian; Wang, Junyue; Requena, Guillermo; Williams, Phillip; Nelson, Johanna; Mehta, Apurva; Andrews, Joy C; Pianetta, Piero

2012-09-01

Determination of the heterogeneous distribution of metals in alloy/battery/catalyst and biological materials is critical to fully characterize and/or evaluate the functionality of the materials. Using synchrotron-based transmission x-ray microscopy (TXM), it is now feasible to perform nanoscale-resolution imaging over a wide X-ray energy range covering the absorption edges of many elements; combining elemental sensitive imaging with determination of sample morphology. We present an efficient and reliable methodology to perform 3D elemental sensitive imaging with excellent sample penetration (tens of microns) using hard X-ray TXM. A sample of an Al-Si piston alloy is used to demonstrate the capability of the proposed method.

Cryogenic x-ray diffraction microscopy utilizing high-pressure cryopreservation

NASA Astrophysics Data System (ADS)

Lima, Enju; Chushkin, Yuriy; van der Linden, Peter; Kim, Chae Un; Zontone, Federico; Carpentier, Philippe; Gruner, Sol M.; Pernot, Petra

2014-10-01

We present cryo x-ray diffraction microscopy of high-pressure-cryofixed bacteria and report high-convergence imaging with multiple image reconstructions. Hydrated D. radiodurans cells were cryofixed at 200 MPa pressure into ˜10-μm-thick water layers and their unstained, hydrated cellular environments were imaged by phasing diffraction patterns, reaching sub-30-nm resolutions with hard x-rays. Comparisons were made with conventional ambient-pressure-cryofixed samples, with respect to both coherent small-angle x-ray scattering and the image reconstruction. The results show a correlation between the level of background ice signal and phasing convergence, suggesting that phasing difficulties with frozen-hydrated specimens may be caused by high-background ice scattering.

Near-edge X-ray refraction fine structure microscopy

DOE PAGES

Farmand, Maryam; Celestre, Richard; Denes, Peter; ...

2017-02-06

We demonstrate a method for obtaining increased spatial resolution and specificity in nanoscale chemical composition maps through the use of full refractive reference spectra in soft x-ray spectro-microscopy. Using soft x-ray ptychography, we measure both the absorption and refraction of x-rays through pristine reference materials as a function of photon energy and use these reference spectra as the basis for decomposing spatially resolved spectra from a heterogeneous sample, thereby quantifying the composition at high resolution. While conventional instruments are limited to absorption contrast, our novel refraction based method takes advantage of the strongly energy dependent scattering cross-section and can seemore » nearly five-fold improved spatial resolution on resonance.« less

Applications of Hard X-ray Full-Field Transmission X-ray Microscopy at SSRL

NASA Astrophysics Data System (ADS)

Liu, Y.; Andrews, J. C.; Meirer, F.; Mehta, A.; Gil, S. Carrasco; Sciau, P.; Mester, Z.; Pianetta, P.

2011-09-01

State-of-the-art hard x-ray full-field transmission x-ray microscopy (TXM) at beamline 6-2C of Stanford Synchrotron Radiation Lightsource has been applied to various research fields including biological, environmental, and material studies. With the capability of imaging a 32-micron field-of-view at 30-nm resolution using both absorption mode and Zernike phase contrast, the 3D morphology of yeast cells grown in gold-rich media was investigated. Quantitative evaluation of the absorption coefficient was performed for mercury nanoparticles in alfalfa roots exposed to mercury. Combining XANES and TXM, we also performed XANES-imaging on an ancient pottery sample from the Roman pottery workshop at LaGraufesenque (Aveyron).

Identifying and managing radiation damage during in situ transmission x-ray microscopy of Li-ion batteries

NASA Astrophysics Data System (ADS)

Nelson, Johanna; Yang, Yuan; Misra, Sumohan; Andrews, Joy C.; Cui, Yi; Toney, Michael F.

2013-09-01

Radiation damage is a topic typically sidestepped in formal discussions of characterization techniques utilizing ionizing radiation. Nevertheless, such damage is critical to consider when planning and performing experiments requiring large radiation doses or radiation sensitive samples. High resolution, in situ transmission X-ray microscopy of Li-ion batteries involves both large X-ray doses and radiation sensitive samples. To successfully identify changes over time solely due to an applied current, the effects of radiation damage must be identified and avoided. Although radiation damage is often significantly sample and instrument dependent, the general procedure to identify and minimize damage is transferable. Here we outline our method of determining and managing the radiation damage observed in lithium sulfur batteries during in situ X-ray imaging on the transmission X-ray microscope at Stanford Synchrotron Radiation Lightsource.

Homepage P. Fischer, LBNL, Berkeley CA | UC Santa Cruz CA

Science.gov Websites

mesoscale magnetic x-ray microscopy and spectroscopy (ultra-)fast spin dynamics soft x-ray tomography of condensed matter x-ray optics publications presentations invited talks conference contributions curriculum

Nanoscale characterization of local structures and defects in photonic crystals using synchrotron-based transmission soft X-ray microscopy

PubMed Central

Nho, Hyun Woo; Kalegowda, Yogesh; Shin, Hyun-Joon; Yoon, Tae Hyun

2016-01-01

For the structural characterization of the polystyrene (PS)-based photonic crystals (PCs), fast and direct imaging capabilities of full field transmission X-ray microscopy (TXM) were demonstrated at soft X-ray energy. PS-based PCs were prepared on an O2-plasma treated Si3N4 window and their local structures and defects were investigated using this label-free TXM technique with an image acquisition speed of ~10 sec/frame and marginal radiation damage. Micro-domains of face-centered cubic (FCC (111)) and hexagonal close-packed (HCP (0001)) structures were dominantly found in PS-based PCs, while point and line defects, FCC (100), and 12-fold symmetry structures were also identified as minor components. Additionally, in situ observation capability for hydrated samples and 3D tomographic reconstruction of TXM images were also demonstrated. This soft X-ray full field TXM technique with faster image acquisition speed, in situ observation, and 3D tomography capability can be complementally used with the other X-ray microscopic techniques (i.e., scanning transmission X-ray microscopy, STXM) as well as conventional characterization methods (e.g., electron microscopic and optical/fluorescence microscopic techniques) for clearer structure identification of self-assembled PCs and better understanding of the relationship between their structures and resultant optical properties. PMID:27087141

Imaging connected porosity of crystalline rock by contrast agent-aided X-ray microtomography and scanning electron microscopy.

PubMed

Kuva, J; Sammaljärvi, J; Parkkonen, J; Siitari-Kauppi, M; Lehtonen, M; Turpeinen, T; Timonen, J; Voutilainen, M

2018-04-01

We set out to study connected porosity of crystalline rock using X-ray microtomography and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) with caesium chloride as a contrast agent. Caesium is an important radionuclide regarding the final deposition of nuclear waste and also forms dense phases that can be readily distinguished by X-ray microtomography and SEM-EDS. Six samples from two sites, Olkiluoto (Finland) and Grimsel (Switzerland), where transport properties of crystalline rock are being studied in situ, were investigated using X-ray microtomography and SEM-EDS. The samples were imaged with X-ray microtomography, immersed in a saturated caesium chloride (CsCl) solution for 141, 249 and 365 days and imaged again with X-ray microtomography. CsCl inside the samples was successfully detected with X-ray microtomography and it had completely penetrated all six samples. SEM-EDS elemental mapping was used to study the location of caesium in the samples in detail with quantitative mineral information. Precipitated CsCl was found in the connected pore space in Olkiluoto veined gneiss and in lesser amounts in Grimsel granodiorite. Only a very small amount of precipitated CsCl was observed in the Grimsel granodiorite samples. In Olkiluoto veined gneiss caesium was found in pinitised areas of cordierite grains. In the pinitised areas caesium was found in notable excess compared to chloride, possibly due to the combination of small pore size and negatively charged surfaces. In addition, elevated concentrations of caesium were found in kaolinite and sphalerite phases. The findings concerning the location of CsCl were congruent with X-ray microtomography. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Interactions between carbamazepine and polyethylene glycol (PEG) 6000: characterisations of the physical, solid dispersed and eutectic mixtures.

PubMed

Naima, Z; Siro, T; Juan-Manuel, G D; Chantal, C; René, C; Jerome, D

2001-02-01

The influence of a hydrophilic carrier (PEG 6000) on the polymorphism of carbamazepine, an antiepileptic drug, was investigated in binary physical mixtures and solid dispersions by means of differential scanning calorimetry (DSC), thermal gravimetry, hot-stage microscopy (HSM), and X-ray diffractometry, respectively. This study provides also an attempt to develop a method to calculate more precisely the eutectic composition. In rather ideal physical mixtures, carbamazepine was found as monoclinic Form III. In solid dispersions, the drug was found to crystallize as trigonal Form II; a eutectic invariant in the PEG 6000-rich composition domain (6% of carbamazepine mass) was evidenced by DSC experiments and confirmed by HSM observations. In the binary phase diagram the ideal carbamazepine liquidus curve was located at temperatures higher than the respective experimental ones. This suggests that drug can be maintained in the liquid state in the temperature-mass fraction (T--x) region between the two carbamazepine liquidus curves. This indicates in turn that attractive interactions occur between carbamazepine and PEG 6000-chains. These interactions have been also claimed to prevent carbamazepine from degradation into iminostilbene (a compound resulting from the chemical degradation of carbamazepine which is postulated to be responsible for the idiosyncratic toxicity of the drug) and thought to lead to the crystallization of metastable Carbamazepine II from melt. The negative excess entropy for eutectic mixtures indicated that the drug crystals are finely dispersed in the bulk of polymer chains.

Polymorphism of Alprazolam (Xanax): a review of its crystalline phases and identification, crystallographic characterization, and crystal structure of a new polymorph (form III).

PubMed

de Armas, Héctor Novoa; Peeters, Oswald M; Van den Mooter, Guy; Blaton, Norbert

2007-05-01

A new polymorphic form of Alprazolam (Xanax), 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo-[4,3-alpha][1,4]benzodiazepine, C(17)H(13)ClN(4), has been investigated by means of X-ray powder diffraction (XRPD), single crystal X-ray diffraction, and differential scanning calorimetry (DSC). This polymorphic form (form III) was obtained during DSC experiments after the exothermic recrystallization of the melt of form I. The crystal unit cell dimensions for form III were determined from diffractometer methods. The monoclinic unit cell found for this polymorph using XRPD after indexing the powder diffractogram was confirmed by the cell parameters obtained from single crystal X-ray diffractometry on a crystal isolated from the DSC pans. The single crystal unit cell parameters are: a = 28.929(9), b = 13.844(8), c = 7.361(3) angstroms, beta = 92.82(3) degrees , V = 2944(2) angstroms(3), Z = 8, space group P2(1) (No.4), Dx = 1.393 Mg/m(3). The structure obtained from single crystal X-ray diffraction was used as initial model for Rietveld refinement on the powder diffraction data of form III. The temperature phase transformations of alprazolam were also studied using high temperature XRPD. A review of the different phases available in the Powder Diffraction File (PDF) database for this drug is described bringing some clarification and corrections. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

Ultraviolet germicidal irradiation and its effects on elemental distributions in mouse embryonic fibroblast cells in x-ray fluorescence microanalysis

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

Jin, Qiaoling; Vogt, Stefan; Lai, Barry

Rapidly-frozen hydrated (cryopreserved) specimens combined with cryo-scanning x-ray fluorescence microscopy provide an ideal approach for investigating elemental distributions in biological cells and tissues. However, because cryopreservation does not deactivate potentially infectious agents associated with Risk Group 2 biological materials, one must be concerned with contamination of expensive and complicated cryogenic x-ray microscopes when working with such materials. We employed ultraviolet germicidal irradiation to decontaminate previously cryopreserved cells under liquid nitrogen, and then investigated its effects on elemental distributions under both frozen hydrated and freeze dried states with x-ray fluorescence microscopy. We show that the contents and distributions of most biologicallymore » important elements remain nearly unchanged when compared with non-ultraviolet-irradiated counterparts, even after multiple cycles of ultraviolet germicidal irradiation and cryogenic x-ray imaging. This provides a potential pathway for rendering Risk Group 2 biological materials safe for handling in multiuser cryogenic x-ray microscopes without affecting the fidelity of the results.« less

Ultraviolet germicidal irradiation and its effects on elemental distributions in mouse embryonic fibroblast cells in x-ray fluorescence microanalysis

DOE PAGES

Jin, Qiaoling; Vogt, Stefan; Lai, Barry; ...

2015-02-23

Rapidly-frozen hydrated (cryopreserved) specimens combined with cryo-scanning x-ray fluorescence microscopy provide an ideal approach for investigating elemental distributions in biological cells and tissues. However, because cryopreservation does not deactivate potentially infectious agents associated with Risk Group 2 biological materials, one must be concerned with contamination of expensive and complicated cryogenic x-ray microscopes when working with such materials. We employed ultraviolet germicidal irradiation to decontaminate previously cryopreserved cells under liquid nitrogen, and then investigated its effects on elemental distributions under both frozen hydrated and freeze dried states with x-ray fluorescence microscopy. We show that the contents and distributions of most biologicallymore » important elements remain nearly unchanged when compared with non-ultraviolet-irradiated counterparts, even after multiple cycles of ultraviolet germicidal irradiation and cryogenic x-ray imaging. This provides a potential pathway for rendering Risk Group 2 biological materials safe for handling in multiuser cryogenic x-ray microscopes without affecting the fidelity of the results.« less

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1-xGaxSe₂ Growth: Indium-Gallium Selenide Co-Evaporation.

PubMed

Pradhan, Puja; Aryal, Puruswottam; Attygalle, Dinesh; Ibdah, Abdel-Rahman; Koirala, Prakash; Li, Jian; Bhandari, Khagendra P; Liyanage, Geethika K; Ellingson, Randy J; Heben, Michael J; Marsillac, Sylvain; Collins, Robert W; Podraza, Nikolas J

2018-01-16

Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In 1- x Ga x )₂Se₃ (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε₁ - iε₂, spectra. Here, RTSE has been used to obtain the (ε₁, ε₂) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents ( x ) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε₁, ε₂) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x . From the resulting database of polynomial coefficients, the (ε₁, ε₂) spectra can be generated for any composition of IGS from the single parameter, x . The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε₁, ε₂) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control.

An epistemology on the nature of polymers.

PubMed

Laridjani, Mortéza; Leboucher, Pierre

2014-01-01

Liquids have neither a periodic structure nor the completely random character of gases therefore the detailed study of their x-ray scattering diagram encounters many difficulties. The idea of periodic regularity in molecules of liquid polymers has been an attractive proposition for the simple interpretation of liquid polymer x-ray diagrams. The categorisation of polymer substances as being between a crystal phase with a perfect order and an amorphous disordered state is an over simplification of the complex reality. For obtaining structural information, during the early stages of the application of x-ray diffraction, a near crystalline model of the molecular arrangements in liquids was utilised. However, the results from these investigations led to just an approximation of the crystalline state. Our studies have analysed the real image of Fourier space of liquid polymers, for the first time, using anomalous diffractometry. The findings show the precise atomic structure of liquid polymers when transformed, by cooling, to solid polymers. We demonstrate that there is an intermediate ordered structure, characterised by the real full image of Fourier space. This prominent state of matter, an intermediate ordered structure, is defined by a regular unit cell with a five-fold symmetry. These structural atomic studies contribute to a more detailed understanding of the properties of polymers than the traditional studies of the degree of crystallinity.

An Epistemology on the Nature of Polymers

PubMed Central

Laridjani, Mortéza; Leboucher, Pierre

2014-01-01

Liquids have neither a periodic structure nor the completely random character of gases therefore the detailed study of their x-ray scattering diagram encounters many difficulties. The idea of periodic regularity in molecules of liquid polymers has been an attractive proposition for the simple interpretation of liquid polymer x-ray diagrams. The categorisation of polymer substances as being between a crystal phase with a perfect order and an amorphous disordered state is an over simplification of the complex reality. For obtaining structural information, during the early stages of the application of x-ray diffraction, a near crystalline model of the molecular arrangements in liquids was utilised. However, the results from these investigations led to just an approximation of the crystalline state. Our studies have analysed the real image of Fourier space of liquid polymers, for the first time, using anomalous diffractometry. The findings show the precise atomic structure of liquid polymers when transformed, by cooling, to solid polymers. We demonstrate that there is an intermediate ordered structure, characterised by the real full image of Fourier space. This prominent state of matter, an intermediate ordered structure, is defined by a regular unit cell with a five-fold symmetry. These structural atomic studies contribute to a more detailed understanding of the properties of polymers than the traditional studies of the degree of crystallinity. PMID:25329440

Complete p-type activation in vertical-gradient freeze GaAs co-implanted with gallium and carbon

NASA Astrophysics Data System (ADS)

Horng, S. T.; Goorsky, M. S.

1996-03-01

High-resolution triple-axis x-ray diffractometry and Hall-effect measurements were used to characterize damage evolution and electrical activation in gallium arsenide co-implanted with gallium and carbon ions. Complete p-type activation of GaAs co-implanted with 5×1014 Ga cm-2 and 5×1014 C cm-2 was achieved after rapid thermal annealing at 1100 °C for 10 s. X-ray diffuse scattering was found to increase after rapid thermal annealing at 600-900 °C due to the aggregation of implantation-induced point defects. In this annealing range, there was ˜10%-72% activation. After annealing at higher annealing temperatures, the diffuse scattered intensity decreased drastically; samples that had been annealed at 1000 °C (80% activated) and 1100 °C (˜100% activated) exhibited reciprocal space maps that were indicative of high crystallinity. The hole mobility was about 60 cm2/V s for all samples annealed at 800 °C and above, indicating that the crystal perfection influences dopant activation more strongly than it influences mobility. Since the high-temperature annealing simultaneously increases dopant activation and reduces x-ray diffuse scattering, we conclude that point defect complexes which form at lower annealing temperatures are responsible for both the diffuse scatter and the reduced activation.

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

NASA Astrophysics Data System (ADS)

Jin, Kuijuan; Wang, Jiesu; Gu, Junxing; L03 Group in Institute of Physics, Chinese Academy of Sciences Team

BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/ χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films. email: kjjin@iphy.ac.cn

Effect of Grinding on the Solid-State Stability and Particle Dissolution of Acyclovir Polymorphs.

PubMed

Magnoni, Federico; Gigliobianco, Maria Rosa; Vargas Peregrina, Dolores; Censi, Roberta; Di Martino, Piera

2017-10-01

The present work investigated the solid state change of 4 acyclovir polymorphs when ground at room temperature (Method A) and under cryo-grinding in the presence of liquid nitrogen (Method B). Modifications in particle size and shape (evaluated by scanning electron microscopy) and in the water content (evaluated by thermal analysis) were related to transitions at the solid state, as confirmed by X-ray powder diffractometry. Anhydrous Form I was stable under grinding by both Methods A and B. The anhydrous Form II was stable during grinding under Method A, whereas it was progressively converted to the hydrate Form V during grinding under Method B. The hydrate Form V was stable under Method A, whereas it was converted to the anhydrous Form I after 15 min and then to the hydrate Form VI after 45 min of grinding. The hydrate Form VI proved to be stable under grinding by both Methods A and B. Thus, Form I and VI were the only forms that yielded a sizeable decrease in particle size under grinding, with a consequent increase in particle dissolution rate, while maintaining solid state physicochemical stability. Form I treated under Method B grinding gave the best dissolution rate. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Oxygen sorption and desorption properties of selected lanthanum manganites and lanthanum ferrite manganites.

PubMed

Nielsen, Jimmi; Skou, Eivind M; Jacobsen, Torben

2015-06-08

Temperature-programmed desorption (TPD) with a carrier gas was used to study the oxygen sorption and desorption properties of oxidation catalysts and solid-oxide fuel cell (SOFC) cathode materials (La(0.85) Sr(0.15)0.95 MnO(3+δ) (LSM) and La(0.60) Sr(0.40) Fe(0.80) Mn(0.20) O(3-δ) (LSFM). The powders were characterized by X-ray diffractometry, atomic force microscopy (AFM), and BET surface adsorption. Sorbed oxygen could be distinguished from oxygen originating from stoichiometry changes. The results indicated that there is one main site for oxygen sorption/desorption. The amount of sorbed oxygen was monitored over time at different temperatures. Furthermore, through data analysis it was shown that the desorption peak associated with oxygen sorption is described well by second-order desorption kinetics. This indicates that oxygen molecules dissociate upon adsorption and that the rate-determining step for the desorption reaction is a recombination of monatomic oxygen. Typical problems with re-adsorption in this kind of TPD setup were revealed to be insignificant by using simulations. Finally, different key parameters of sorption and desorption were determined, such as desorption activation energies, density of sorption sites, and adsorption and desorption reaction order. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of mineralized electrospun PLGA and PLGA/gelatin nanofibers and their potential in bone tissue engineering.

PubMed

Meng, Z X; Li, H F; Sun, Z Z; Zheng, W; Zheng, Y F

2013-03-01

Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(D,L-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity. Copyright © 2012 Elsevier B.V. All rights reserved.

A Novel Microcharacterization Technique in the Measurement of Strain and Orientation Gradient in Advanced Materials

NASA Technical Reports Server (NTRS)

Garmestai, H.; Harris, K.; Lourenco, L.

1997-01-01

Representation of morphology and evolution of the microstructure during processing and their relation to properties requires proper experimental techniques. Residual strains, lattice distortion, and texture (micro-texture) at the interface and the matrix of a layered structure or a functionally gradient material and their variation are among parameters important in materials characterization but hard to measure with present experimental techniques. Current techniques available to measure changes in interred material parameters (residual stress, micro-texture, microplasticity) produce results which are either qualitative or unreliable. This problem becomes even more complicated in the case of a temperature variation. These parameters affect many of the mechanical properties of advanced materials including stress-strain relation, ductility, creep, and fatigue. A review of some novel experimental techniques using recent advances in electron microscopy is presented here to measure internal stress, (micro)texture, interracial strength and (sub)grain formation and realignment. Two of these techniques are combined in the chamber of an Environmental Scanning Electron Microscope to measure strain and orientation gradients in advanced materials. These techniques which include Backscattered Kikuchi Diffractometry (BKD) and Microscopic Strain Field Analysis are used to characterize metallic and intermetallic matrix composites and superplastic materials. These techniques are compared with the more conventional x-ray diffraction and indentation techniques.

Cu-Doped ZnO Thin Films Deposited by a Sol-Gel Process Using Two Copper Precursors: Gas-Sensing Performance in a Propane Atmosphere.

PubMed

Gómez-Pozos, Heberto; Arredondo, Emma Julia Luna; Maldonado Álvarez, Arturo; Biswal, Rajesh; Kudriavtsev, Yuriy; Pérez, Jaime Vega; Casallas-Moreno, Yenny Lucero; Olvera Amador, María de la Luz

2016-01-29

A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS), respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C₃H₈, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 10⁴, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C₃H₈ gas.

Separation of Lead from Crude Antimony by Pyro-Refining Process with NaPO3 Addition

NASA Astrophysics Data System (ADS)

Ye, Longgang; Hu, Yuejie; Xia, Zhimei; Chen, Yongming

2016-06-01

The main purpose of this study was to separate lead from crude antimony through an oxidation pyro-refining process and by using sodium metaphosphate as a lead elimination reagent. The process parameters that will affect the refining results were optimized experimentally under controlled conditions, such as the sodium metaphosphate charging dosage, the refining temperature and duration, and the air flow rate, to determine their effect on the lead content in refined antimony and the lead removal rate. A minimum lead content of 0.0522 wt.% and a 98.6% lead removal rate were obtained under the following optimal conditions: W_{{{NaPO}_{{3}} }} = 15% W Sb (where W represents weight), a refining temperature of 800°C, a refining time of 30 min, and an air flow rate of 3 L/min. X-ray diffractometry and scanning electron microscopy showed that high-purity antimony was obtained. The smelting operation is free from smoke or ammonia pollution when using monobasic sodium phosphate or ammonium dihydrogen phosphate as the lead elimination reagent. However, this refining process can also remove a certain amount of sulfur, cobalt, and silicon simultaneously, and smelting results also suggest that sodium metaphosphate can be used as a potential lead elimination reagent for bismuth and copper refining.

Composite HPMC and sodium alginate based buccal formulations for nicotine replacement therapy.

PubMed

Okeke, Obinna C; Boateng, Joshua S

2016-10-01

Smoking cessation is of current topical interest due to the significant negative health and economic impact in many countries. This study aimed to develop buccal films and wafers comprising HPMC and sodium alginate (SA) for potential use in nicotine replacement therapy via the buccal mucosa, as a cheap but effective alternative to currently used nicotine patch and chewing gum. The formulations were characterised using texture analyser (tensile and hardness, mucoadhesion), scanning electron microscopy, X-ray diffractometry, attenuated total reflection-Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC) and swelling capacity. Drug loaded films and wafers were characterised for content uniformity (HPLC) whilst the drug loaded wafers only were further characterised for in vitro drug dissolution. SA modified and improved the functional properties of HPMC at optimum ratio of HPMC: SA of 1.25: 0.75. Generally, both films and wafers (blank and drug loaded) were amorphous in nature which impacted on swelling and mucoadhesive performance. HPMC-SA composite wafers showed a porous internal morphology with higher mucoadhesion, swelling index and drug loading capacity compared to the HPMC-SA composite films which were non-porous. The study demonstrates the potential use of composite HPMC-SA wafers in the buccal delivery nicotine. Copyright © 2016 Elsevier B.V. All rights reserved.

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation.

PubMed

Wang, Jie-Su; Jin, Kui-Juan; Guo, Hai-Zhong; Gu, Jun-Xing; Wan, Qian; He, Xu; Li, Xiao-Long; Xu, Xiu-Lai; Yang, Guo-Zhen

2016-12-01

BiFeO 3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO 3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO 3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO 3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO 3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO 3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ 31 /χ 15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO 3 thin films.

Evolution of structural distortion in BiFeO3 thin films probed by second-harmonic generation

PubMed Central

Wang, Jie-su; Jin, Kui-juan; Guo, Hai-zhong; Gu, Jun-xing; Wan, Qian; He, Xu; Li, Xiao-long; Xu, Xiu-lai; Yang, Guo-zhen

2016-01-01

BiFeO3 thin films have drawn much attention due to its potential applications for novel magnetoelectric devices and fundamental physics in magnetoelectric coupling. However, the structural evolution of BiFeO3 films with thickness remains controversial. Here we use an optical second-harmonic generation technique to explore the phase-related symmetry evolution of BiFeO3 thin films with the variation of thickness. The crystalline structures for 60 and 180-nm-thick BiFeO3 thin films were characterized by high-resolution X-ray diffractometry reciprocal space mapping and the local piezoelectric response for 60-nm-thick BiFeO3 thin films was characterized by piezoresponse force microscopy. The present results show that the symmetry of BiFeO3 thin films with a thickness below 60 nm belongs to the point group 4 mm. We conclude that the disappearance of fourfold rotational symmetry in SHG s-out pattern implies for the appearance of R-phase. The fact that the thinner the film is, the closer to 1 the tensor element ratio χ31/χ15 tends, indicates an increase of symmetry with the decrease of thickness for BiFeO3 thin films. PMID:27905565

In Situ Synthesis of Silver Nanoparticles on the Polyelectrolyte-Coated Sericin/PVA Film for Enhanced Antibacterial Application

PubMed Central

Cai, Rui; Tao, Gang; Guo, Pengchao; Yang, Meirong; Ding, Chaoxiang; Zuo, Hua; Wang, Lingyan; Zhao, Ping; Wang, Yejing

2017-01-01

To develop silk sericin (SS) as a potential antibacterial biomaterial, a novel composite of polyelectrolyte multilayers (PEMs) coated sericin/poly(vinyl alcohol) (SS/PVA) film modified with silver nanoparticles (AgNPs) has been developed using a layer-by-layer assembly technique and ultraviolet-assisted AgNPs synthesis method. Ag ions were enriched by PEMs via the electrostatic attraction between Ag ions and PEMs, and then reduced to AgNPs in situ with the assistance of ultraviolet irradiation. PEMs facilitated the high-density growth of AgNPs and protected the synthesized AgNPs due to the formation of a 3D matrix, and thus endowed SS/PVA film with highly effective and durable antibacterial activity. Scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, Fourier transfer infrared spectroscopy, water contact angle, mechanical property and thermogravimetric analysis were applied to characterize SS/PVA, PEMs-SS/PVA and AgNPs-PEMs-SS/PVA films, respectively. AgNPs-PEMs-SS/PVA film has exhibited good mechanical performance, hydrophilicity, water absorption capability as well as excellent and durable antibacterial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and good stability and degradability. This study has developed a simple method to design and prepare AgNPs-PEMs-SS/PVA film for potential antibacterial application. PMID:28820482

Influence of the interface layer on the adhesion of pulsed laser deposited hydroxyapatite coatings on titanium alloy

NASA Astrophysics Data System (ADS)

Fernández-Pradas, J. M.; García-Cuenca, M. V.; Clèries, L.; Sardin, G.; Morenza, J. L.

2002-07-01

Hydroxyapatite (HA) coatings were deposited on Ti-6Al-4V substrates by laser ablation with a KrF excimer laser. Depositions were performed at 45 Pa of water vapour and at a substrate temperature of 575 °C. After 7 min of deposition, coatings were left at this temperature for different times before cooling down. The samples morphology and structure were characterised by scanning electron microscopy, X-ray diffractometry and Raman spectroscopy. The mechanical performance of the coatings was evaluated through the scratch-test technique. The coatings do not present important differences between them. However, there is an interface layer between the coating and the substrate that indeed presents an evolution with the heating time. This interface layer is constituted by two different species: titanium oxide and Ti-6Al-4V with oxygen diffused in its lattice. Its thickness increases during the first minutes of heating after deposition. An evolution of the titanium oxide phases with the time of heating has been detected by Raman spectroscopy. The samples fail at lower loads in the scratch-test as longer is the time that they remained at high temperature. The mode of failure of the samples suggests that failure occurs at the interface.

Devitrification studies of wollastonite-tricalcium phosphate eutectic glass.

PubMed

Magallanes-Perdomo, M; Pena, P; De Aza, P N; Carrodeguas, R G; Rodríguez, M A; Turrillas, X; De Aza, S; De Aza, A H

2009-10-01

The present paper describes and discusses the devitrification and crystallization process of wollastonite-tricalcium phosphate (W-TCP) eutectic glass. This process was studied in situ from room temperature up to 1375 degrees C, by neutron diffractometry in vacuum. The data obtained were combined and compared with those performed in ambient atmosphere by differential thermal analysis and with those of samples fired in air at selected temperatures, and then cooled down and subsequently studied by laboratory XRD and field emission scanning electron microscopy fitted with energy X-ray dispersive spectroscopy. The experimental evidence indicates that the devitrification of W-TCP eutectic glass begins at approximately 870 degrees C with the crystallization of a Ca-deficient apatite phase, followed by wollastonite-2M (CaSiO(3)) crystallization at approximately 1006 degrees C. At 1375 degrees C, the bio-glass-ceramic is composed of quasi-rounded colonies formed by a homogeneous mixture of pseudowollastonite (CaSiO(3)) and alpha-tricalcium phosphate (Ca(3)(PO(4))(2)). This microstructure corresponds to irregular eutectic structures. It was also found that it is possible to obtain from the eutectic composition of the wollastonite-tricalcium phosphate binary system a wide range of bio-glass-ceramics, with different crystalline phases present, through appropriate design of thermal treatments.

Effect of Temperature and Growth Time on Vertically Aligned ZnO Nanorods by Simplified Hydrothermal Technique for Photoelectrochemical Cells.

PubMed

Mohd Fudzi, Laimy; Zainal, Zulkarnain; Lim, Hong Ngee; Chang, Sook-Keng; Holi, Araa Mebdir; Sarif Mohd Ali, Mahanim

2018-04-29

Despite its large band gap, ZnO has wide applicability in many fields ranging from gas sensors to solar cells. ZnO was chosen over other materials because of its large exciton binding energy (60 meV) and its stability to high-energy radiation. In this study, ZnO nanorods were deposited on ITO glass via a simple dip coating followed by a hydrothermal growth. The morphological, structural and compositional characteristics of the prepared films were analyzed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Photoelectrochemical conversion efficiencies were evaluated via photocurrent measurements under calibrated halogen lamp illumination. Thin film prepared at 120 °C for 4 h of hydrothermal treatment possessed a hexagonal wurtzite structure with the crystallite size of 19.2 nm. The average diameter of the ZnO nanorods was 37.7 nm and the thickness was found to be 2680.2 nm. According to FESEM images, as the hydrothermal growth temperature increases, the nanorod diameter become smaller. Moreover, the thickness of the nanorods increase with the growth time. Therefore, the sample prepared at 120 °C for 4 h displayed an impressive photoresponse by achieving high current density of 0.1944 mA/cm².

Comparative evaluation of ibuprofen/beta-cyclodextrin complexes obtained by supercritical carbon dioxide and other conventional methods.

PubMed

Hussein, Khaled; Türk, Michael; Wahl, Martin A

2007-03-01

The preparation of drug/cyclodextrin complexes is a suitable method to improve the dissolution of poor soluble drugs. The efficacy of the Controlled Particle Deposition (CPD) as a new developed method to prepare these complexes in a single stage process using supercritical carbon dioxide is therefore compared with other conventional methods. Ibuprofen/beta-cyclodextrin complexes were prepared with different techniques and characterized using FTIR-ATR spectroscopy, powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In addition, the influences of the processing technique on the drug content (HPLC) and the dissolution behavior were studied. Employing the CPD-process resulted in a drug content of 2.8+/-0.22 wt.% in the carrier. The material obtained by CPD showed an improved dissolution rate of ibuprofen at pH 5 compared with the pure drug and its physical mixture with beta-cyclodextrin. In addition CPD material displays the highest dissolution (93.5+/- 2.89% after 75 min) compared to material obtained by co-precipitation (61.3 +/-0.52%) or freeze-drying (90.6 +/-2.54%). This study presents the CPD-technique as a well suitable method to prepare a drug/beta-cyclodextrin complex with improved drug dissolution compared to the pure drug and materials obtained by other methods.

Enhanced bioactivity, biocompatibility and mechanical behavior of strontium substituted bioactive glasses.

PubMed

Arepalli, Sampath Kumar; Tripathi, Himanshu; Hira, Sumit Kumar; Manna, Partha Pratim; Pyare, Ram; S P Singh

2016-12-01

Strontium contained biomaterials have been reported as a potential bioactive material for bone regeneration, as it reduces bone resorption and stimulates bone formation. In the present investigation, the bioactive glasses were designed to partially substitute SrO for SiO2 in Na2O-CaO-SrO-P2O5-SiO2 system. This work demonstrates that the substitution of SrO for SiO2 has got significant benefit than substitution for CaO in the bioactive glass. Bioactivity was assessed by the immersion of the samples in simulated body fluid for different intervals. The formation of hydroxy carbonate apatite layer was identified by X-ray diffractometry, scanning electron microscopy (SEM) and energy dispersive spectroscopy. The elastic modulus of the bioactive glasses was measured and found to increase with increasing SrO for SiO2. The blood compatibility of the samples was evaluated. In vitro cell culture studies of the samples were performed using human osteosarcoma U2-OS cell lines and found a significant improvement in cell viability and proliferation. The investigation showed enhancement in bioactivity, mechanical and biological properties of the strontia substituted for silica in glasses. Thus, these bioactive glasses would be highly potential for bone regeneration. Copyright © 2016 Elsevier B.V. All rights reserved.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

PubMed Central

Liu, Peng; Chen, Ying; Yu, Zhiwu

2016-01-01

A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570), and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrscopy, X-ray diffractometry (XRD), contact angle meter (CA), and scanning electron microscope (SEM). The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570). Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures. PMID:28774141

Microstructure and Plastic Deformation of the As-Welded Invar Fusion Zones

NASA Astrophysics Data System (ADS)

Yao, D. J.; Zhou, D. R.; Xu, P. Q.; Lu, F. G.

2017-05-01

The as-welded Invar fusion zones were fabricated between cemented carbides and carbon steel using a Fe-Ni Invar interlayer and laser welding method. Three regions in the as-welded Invar fusion zones were defined to compare microstructures, and these were characterized and confirmed by scanning electron microscopy and X-ray diffractometry. The structure and plastic deformation mechanism for initial Invar Fe-Ni alloys and the as-welded Invar fusion zones are discussed. (1) After undergoing high-temperature thermal cycles, the microstructure of the as-welded Invar fusion zones contains γ-(Fe, Ni) solid solution (nickel dissolving in γ-Fe) with a face-centered cubic (fcc) crystal structure and mixed carbides (eutectic colonies, mixed carbides between two adjacent grains). The mixed carbides exhibited larger, coarser eutectic microstructures with a decrease in welding speed and an increase in heat input. (2) The structure of the initial Invar and the as-welded Invar is face-centered cubic γ-(Fe, Ni). (3) The as-welded Invar has a larger plastic deformation than initial Invar with an increase in local strain field and dislocation density. Slip deformation is propagated along the (111) plane. This finding helps us to understand microstructure and the formation of dislocation and plastic deformation when the Invar Fe-Ni alloy undergoes a high-temperature process.

Improving the Thermal Shock Resistance of Thermal Barrier Coatings Through Formation of an In Situ YSZ/Al2O3 Composite via Laser Cladding

NASA Astrophysics Data System (ADS)

Soleimanipour, Zohre; Baghshahi, Saeid; Shoja-razavi, Reza

2017-04-01

In the present study, laser cladding of alumina on the top surface of YSZ thermal barrier coatings (TBC) was conducted via Nd:YAG pulsed laser. The thermal shock behavior of the TBC before and after laser cladding was modified by heating at 1000 °C for 15 min and quenching in cold water. Phase analysis, microstructural evaluation and elemental analysis were performed using x-ray diffractometry, scanning electron microscopy (SEM), and energy-dispersive spectroscopy. The results of thermal shock tests indicated that the failure in the conventional YSZ (not laser clad) and the laser clad coatings happened after 200 and 270 cycles, respectively. The SEM images of the samples showed that delamination and spallation occurred in both coatings as the main mechanism of failure. Formation of TGO was also observed in the fractured cross section of the samples, which is also a main reason for degradation. Thermal shock resistance in the laser clad coatings improved about 35% after cladding. The improvement is due to the presence of continuous network cracks perpendicular to the surface in the clad layer and also the thermal stability and high melting point of alumina in Al2O3/ZrO2 composite.

A study of Bi-Pb-Sn-Cd-Sb penta-alloys rapidly quenched from melt

NASA Astrophysics Data System (ADS)

Kamal, M.; El-Bediwi, A. B.

2004-11-01

Optical microscopy, X-ray diffractometry, the double bridge method, the Vickers microhardness testing and dynamic resonance techniques have been used to investigate structure, electrical resistivity, hardness, internal friction and elastic modulus of quenched Bi-Pb-Sn-Cd-Sb penta-alloys. The properties of these penta-alloys are greatly affected by rapid quenching. The intermetallic compound chi(Pb-Bi) or Bi3Pb7 is obtained after rapid quenching using the melt-spinning technique, and this is in agreement with reports by other authors [Marshall, T.J., Mott, G. T. and Grieverson, M. H. (1975). Br. J. Radiol., 48, 924, Kamal, M., El-Bediwi, A. B. and Karman, M. B. (1998). Structure, mechanical properties and electrical resistivity of rapidly solidified Pb-Sn-Cd and Pb-Bi-Sn-Cd alloys. J. Mater. Sci.: Mater. Electron., 9, 425, Borromee-Gautier, C., Giessen, B. C. and Grrant, N. J. (1968). J. Chem. Phys., 48,1905, Moon, K.-W., Boettinger, W. J., Kanner, U. R., Handwerker, C. A. and Lee, D.-J. (2001). The effect of Pb contamination on the solidification behavior of Sn-Bi solders. J. Electron. Mater, 30, 45.]. The quenched Bi43.5Pb44.5Cd5Sn2Sb5 alloy has important properties for safety devices in fire detection and extinguishing systems.

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

Chen Long; Department of Chemistry, Huangshan University, Huangshan 245041; Post-Doctoral Scientific Research Workstation, HuangShan NOVEL Co. Ltd, Huangshan 245061

In this paper, biomimetic synthesis of aragonite superstructures using a low molecular weight organic-hexamethylenetetramine (HMT) as an additive in the presence of CO{sub 2} supplied by an ammonium carbonate ((NH{sub 4}){sub 2}CO{sub 3}) diffusion method at room temperature was studied. The products were characterized by scanning or transmission electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffractometry, and selected area electron diffraction. The results showed the aragonite superstructures especially dumbbell-flower-like ones were obtained. The formation process of calcium carbonate (CaCO{sub 3}) in HMT aqueous solution was investigated, suggesting that the products transformed from calcite to vaterite primarily, and thenmore » changed into a mixture of aragonite and calcite with an increase of reaction time. The formation mechanism of CaCO{sub 3} in HMT solution was also discussed, revealing that aragonite might be controlled by HMT molecules and NH{sub 4}{sup +} ions together. - Graphical abstract: The well-defined aragonite hierarchical superstructures are formed using hexamethylenetetramine in aqueous solution. Highlights: > Aragonite superstructures are formed with hexamethylenetetramine at about 25 deg. C. > Dumbbell-flower-like aragonite produces when hexamethylenetetramine/Ca{sup 2+}=10:1. > CaCO{sub 3} formation in hexamethylenetetramine solution violates the Ostwald ripening. > Hexamethylenetetramine and NH{sub 4}{sup +} might control the growth of aragonite together.« less

Wood (Bagassa guianensis Aubl) and green coconut mesocarp (cocos nucifera) residues as textile dye removers (Remazol Red and Remazol Brilliant Violet).

PubMed

Monteiro, Mônica S; de Farias, Robson F; Chaves, José Alberto Pestana; Santana, Sirlane A; Silva, Hildo A S; Bezerra, Cícero W B

2017-12-15

In this work the efficiency of two lignocellulosic waste materials, wood residues and coconut mesocarp, were investigated as adsorbents towards two representative textile dyes (Remazol Red, RR and Remazol Brilliant Violet, RBV). The moisture, carbohydrate, protein, lipid, ash and fiber contents of both natural matrices were characterized. The materials were also characterized by infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, specific surface area analysis and thermogravimetry. The adsorption of dyes was monitored by using UV-Vis spectrophotometry. It was verified that both, coconut mesocarp (CM) and wood residues can act as effective adsorbents towards the investigated dyes. It is verified that the maximum adsorption capacity Γ M (mg g -1 ) for RBV and RR are 7.28 and 3.97 towards CM and 0.64 and 0.71 towrads SD. Furthermore, it was verified that the adsorption is strongly pH dependent and, as a general behavior, an increase in the pH value is associated with a decrease of the total amount of adsorbed dye. The adsorption of violet dye onto coconut mesocarp is well described by the Langmuir model, while all the remazol red fitted better with the Freundlich equation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Scanning electron and atomic force microscopy, and raman and x-ray photoelectron spectroscopy characterization of near-isogenic soft and hard wheat kernels and corresponding flours

USDA-ARS?s Scientific Manuscript database

Atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) are used to investigate vitreous (hard) and non-vitreous (soft) wheat kernels and their corresponding wheat flours. AFM data reveal two different microstructures. The vitreous kernel reveals a granular text...

Refractive Optics for Hard X-ray Transmission Microscopy

NASA Astrophysics Data System (ADS)

Simon, M.; Ahrens, G.; Last, A.; Mohr, J.; Nazmov, V.; Reznikova, E.; Voigt, A.

2011-09-01

For hard x-ray transmission microscopy at photon energies higher than 15 keV we design refractive condenser and imaging elements to be used with synchrotron light sources as well as with x-ray tube sources. The condenser lenses are optimized for low x-ray attenuation—resulting in apertures greater than 1 mm—and homogeneous intensity distribution on the detector plane, whereas the imaging enables high-resolution (<100 nm) full-field imaging. To obtain high image quality at reasonable exposure times, custom-tailored matched pairs of condenser and imaging lenses are being developed. The imaging lenses (compound refractive lenses, CRLs) are made of SU-8 negative resist by deep x-ray lithography. SU-8 shows high radiation stability. The fabrication technique enables high-quality lens structures regarding surface roughness and arrangement precision with arbitrary 2D geometry. To provide point foci, crossed pairs of lenses are used. Condenser lenses have been made utilizing deep x-ray lithographic patterning of thick SU-8 layers, too, whereas in this case, the aperture is limited due to process restrictions. Thus, in terms of large apertures, condenser lenses made of structured and rolled polyimide film are more attractive. Both condenser types, x-ray mosaic lenses and rolled x-ray prism lenses (RXPLs), are considered to be implemented into a microscope setup. The x-ray optical elements mentioned above are characterized with synchrotron radiation and x-ray laboratory sources, respectively.

Structure-substitution limit correlation study on Cr{sup 3+} substituted polycrystalline yttrium iron garnet

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

Modi, K. B.; Saija, K. G.; Sharma, P. U.

2016-05-06

Polycrystalline samples of Cr{sup 3+} - substituted yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}) system with general chemical formula, Y{sub 3}Fe{sub 5-x}Cr{sub x}O{sub 12}, x = 0.0, 0.2, 0.4 and 0.6 were synthesized by double sintering ceramic technique and characterized by X-ray powder diffractometry. The Rietveld fitted X-ray diffraction patterns analysis revealed mono phase formation for x = 0.0 - 0.4 compositions while x = 0.6 composition possesses mixed phase character. The observed substitution limit has been discussed in the light of ionic size of substituent, electrostatic energy, electronic configuration and synthesis parameters. These observations strongly suggest that the electronicmore » configuration of Cr{sup 3+}, which is favorable to the formation of d2sp3 (octahedral) type bonds, must be important. In the case of Cr{sup 3+}, the substitution does not appear to proceed well for x much greater than 0.5, this limitation probably is a consequence of the strong preference of a smaller ion Cr{sup 3+}, for a larger octahedral site which quickly leads to a condition not comparable with the requirement of the structure. The distribution of cations, mean ionic radii and theoretical lattice constant values have been determined.« less

3-D Cellular Ultrastructure Can Be Resolved by X-ray Microscopy | Center for Cancer Research

Cancer.gov

X-ray microscopy (XRM) is more rapid than cryoelectron tomography or super-resolution fluorescence microscopy and could fill an important gap in current technologies used to investigate in situ three-dimensional structure of cells. New XRM methods developed by first author Gerd Schneider, Ph.D., working with James McNally. Ph.D., and a team of colleagues, is capable of revealing full cellular ultrastructure without requiring fixation, staining, or sectioning.

Laboratory-size three-dimensional water-window x-ray microscope with Wolter type I mirror optics

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

Ohsuka, Shinji; The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsu-cho, Nishi-ku, Hamamatsu-City, 431-1202; Ohba, Akira

2016-01-28

We constructed a laboratory-size three-dimensional water-window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques. It consists of an electron-impact x-ray source emitting oxygen Kα x-rays, Wolter type I grazing incidence mirror optics, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit better than 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-μm-scale three-dimensional fine structures were resolved.

The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy

PubMed Central

Lan, Xiangna; Wang, Chao; Zhang, Qinyong

2018-01-01

Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO4·3H2O, MnHPO4·2.25H2O, BaHPO4·3H2O, BaMg2(PO4)2, Mg3(PO4)2·22H2O, Ca3(PO4)2·xH2O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl. PMID:29518038

Contact x-ray microscopy using Asterix

NASA Astrophysics Data System (ADS)

Conti, Aldo; Batani, Dimitri; Botto, Cesare; Masini, Alessandra; Bernardinello, A.; Bortolotto, Fulvia; Moret, M.; Poletti, G.; Piccoli, S.; Cotelli, F.; Lora Lamia Donin, C.; Stead, Anthony D.; Marranca, A.; Eidmann, Klaus; Flora, Francesco; Palladino, Libero; Reale, Lucia

1997-10-01

The use of a high energy laser source for soft x-ray contact microscopy is discussed. Several different targets were used and their emission spectra compared. The x-ray emission, inside and outside the Water Window, was characterized in detail by means of many diagnostics, including pin hole and streak cameras. Up to 12 samples holders per shot were exposed thanks to the large x-ray flux and the geometry of the interaction chamber. Images of several biological samples were obtained, including Chlamydomonas and Crethidia green algae, fish and boar sperms and Saccharomyces Cerevisiae yeast cells. A 50 nm resolution was reached on the images of boar sperm. Original information concerning the density of inner structures of Crethidia green algae were obtained.

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

Wedding, Jason L.; Harris, Hugh H.; Bader, Christie A.

Optical fluorescence microscopy was used in conjunction with X-ray fluorescence microscopy to monitor the stability and intracellular distribution of the luminescent rhenium(I) complex fac-[Re(CO) 3(phen)L], where phen = 1,10-phenathroline and L = 5-(4-iodophenyl)tetrazolato, in 22Rv1 cells. The rhenium complex showed no signs of ancillary ligand dissociation, a conclusion based on data obtained via X-ray fluorescence imaging aligning iodine and rhenium distributions. A diffuse reticular localisation was detected for the complex, in the nuclear/perinuclear region of cells, by either optical or X-ray fluorescence techniques. Furthermore, X-ray fluorescence also showed that the Re-I complex disrupted the homeostasis of some biologically relevant elements,more » such as chlorine, potassium and zinc.« less

Microstructure Analysis of Bismuth Absorbers for Transition-Edge Sensor X-ray Microcalorimeters

NASA Astrophysics Data System (ADS)

Yan, Daikang; Divan, Ralu; Gades, Lisa M.; Kenesei, Peter; Madden, Timothy J.; Miceli, Antonino; Park, Jun-Sang; Patel, Umeshkumar M.; Quaranta, Orlando; Sharma, Hemant; Bennett, Douglas A.; Doriese, William B.; Fowler, Joseph W.; Gard, Johnathon D.; Hays-Wehle, James P.; Morgan, Kelsey M.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N.

2018-03-01

Given its large X-ray stopping power and low specific heat capacity, bismuth (Bi) is a promising absorber material for X-ray microcalorimeters and has been used with transition-edge sensors (TESs) in the past. However, distinct X-ray spectral features have been observed in TESs with Bi absorbers deposited with different techniques. Evaporated Bi absorbers are widely reported to have non-Gaussian low-energy tails, while electroplated ones do not show this feature. In this study, we fabricated Bi absorbers with these two methods and performed microstructure analysis using scanning electron microscopy and X-ray diffraction microscopy. The two types of material showed the same crystallographic structure, but the grain size of the electroplated Bi was about 40 times larger than that of the evaporated Bi. This distinction in grain size is likely to be the cause of their different spectral responses.

High-resolution ab initio three-dimensional x-ray diffraction microscopy

DOE PAGES

Chapman, Henry N.; Barty, Anton; Marchesini, Stefano; ...

2006-01-01

Coherent x-ray diffraction microscopy is a method of imaging nonperiodic isolated objects at resolutions limited, in principle, by only the wavelength and largest scattering angles recorded. We demonstrate x-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images. These images are retrieved from the three-dimensional diffraction data using no a priori knowledge about the shape or composition of the object, which has never before been demonstrated on a nonperiodic object. We also construct two-dimensional images of thick objects with greatly increased depth of focus (without loss of transverse spatialmore » resolution). These methods can be used to image biological and materials science samples at high resolution with x-ray undulator radiation and establishes the techniques to be used in atomic-resolution ultrafast imaging at x-ray free-electron laser sources.« less

A versatile soft X-ray transmission system for time resolved in situ microscopy with chemical contrast.

PubMed

Forsberg, J; Englund, C-J; Duda, L-C

2009-08-01

We present the design and operation of a versatile soft X-ray transmission system for time resolved in situ microscopy with chemical contrast. The utility of the setup is demonstrated by results from following a corrosion process of iron in saline environment, subjected to a controlled humid atmosphere. The system includes a transmission flow-cell reactor that allows for in situ microscopic probing with soft X-rays. We employ a full field technique by using a nearly collimated X-ray beam that produces an unmagnified projection of the transmitted soft X-rays (below 1.1 keV) which is magnified and recorded by an optical CCD camera. Time lapse series with chemical contrast allow us to follow and interpret the chemical processes in detail. The obtainable lateral resolution is a few mum, sufficient to detect filiform corrosion on iron.

Investigation and Control of "Sphere-Like" Buckminsterfullerene C60 and "Disk-Like" Copper(II) Phthalocyanine

NASA Astrophysics Data System (ADS)

McAfee, Terry Richard

Due to the growing global need for cheap, flexible, and portable electronics, numerous research groups from mechanical and electrical engineering, material science, chemistry, and physics have increasingly turned to organic electronics research over the last ˜5--10 years. Largely, the focus of researchers in this growing field have sought to obtain the next record holding device, allowing a heuristic approach of trial and error to become dominant focus of research rather than a fundamental understanding. Rather than working with the latest high performance organic semiconducting materials and film processing techniques, I have chosen to investigate and control the fundamental self-assembly interactions of organic photovoltaic thin films using simplified systems. Specifically, I focus on organic photovoltaic research using two of the oldest and well studies semiconducting materials, namely "sphere-like" electron donor material Buckminsterfullerene C60 and "disklike" electron acceptor material Copper(II) Phthalocyanine. I manufactured samples using the well-known technique of physical vapor deposition using a high vacuum chamber that I designed and built to accommodate my need of precise material deposition control, with codeposition capability. Films were characterized using microscopy and spectroscopy techniques locally at NCSU, including Atomic Force Microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and Ultraviolet-visible spectroscopy, as well as at National Laboratory based synchrotron x-ray techniques, including Carbon and Nitrogen k-edge Total Electron Yield and Transmission Near Edge X-ray absorption fine structure spectroscopy, Carbon k-edge Resonant Soft x-ray Microscopy, Resonant Soft x-ray reflectivity, and Grazing Incidence Wide-Angle X-ray scattering.

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

Alves, L. M. S., E-mail: leandro-fisico@hotmail.com; Lima, B. S. de; Santos, C. A. M. dos

K{sub 0.05}MoO{sub 2} has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO{sub 2} compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature.

Effect of thermal history on Mossbauer signature and hyperfine interaction parameters of copper ferrite

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

Modi, K. B., E-mail: kunalbmodi2003@yahoo.com; Raval, P. Y.; Dulera, S. V.

Two specimens of copper ferrite, CuFe{sub 2}O{sub 4}, have been synthesized by double sintering ceramic technique with different thermal history i.e. slow cooled and quenched. X-ray diffractometry has confirmed single phase fcc spinel structure for slow cooled sample while tetragonal distortion is present in quenched sample. Mossbauer spectral analysis for slow-cooled copper ferrite reveals super position of two Zeeman split sextets along with paramagnetic singlet in the centre position corresponds to delafossite (CuFeO{sub 2}) phase that is completely absent in quenched sample. The hyperfine interaction parameters are highly influenced by heat treatment employed.

The polymorphic and mesomorphic behavior of four esters of cholesterol.

NASA Technical Reports Server (NTRS)

Merritt, W. G.; Cole, G. D.; Walker, W. W.

1971-01-01

The techniques of differential scanning calorimetry, X-ray powder diffractometry, and positron annihilation have been used to study the polymorphic and mesomorphic behavior of the following esters of cholesterol: cholesteryl formate, cholesteryl butyrate, cholesteryl benzoate, and cholesteryl cinnamate. Each of these compounds exhibits a single mesophase of the cholesteric type. The solid phase formed from the melt for each ester was observed to be structurally different from the solid phase obtained from solution. Solvents from which the solution-grown samples were crystallized were as follows: cholesteryl formate and cholesteryl butyrate from acetone, cholesteryl benzoate from benzene, and cholesteryl cinnamate from 2-butanone.

You can't measure what you can't see - detectors for microscopies

NASA Astrophysics Data System (ADS)

Denes, Peter

For centuries, the human eye has been the imaging detector of choice thanks to its high sensitivity, wide dynamic range, and direct connection to a built-in data recording and analysis system. The eye, however, is limited to visible light, which excludes microscopies with electrons and X-rays, and the built-in recording system stores archival information at very low rates. The former limitation has been overcome by ``indirect'' detectors, which convert probe particles to visible light, and the latter by a variety of recording techniques, from photographic film to semiconductor-based imagers. Semiconductor imagers have been used for decades as ``direct'' detectors in particle physics, and almost as long for hard X-rays. For soft X-ray microscopy, the challenge has been the small signal levels - plus getting the X-rays into the detector itself, given how quickly they are absorbed in inert layers. For electron microscopy, the challenge has been reconciling detector spatial resolution and pixel count with the large multiple scattering of electrons with energies used for microscopy. Further, a high recording rate (``movies'' rather than ``snapshots'') enables time-resolved studies, time-dependent corrections, shot-by-shot experiments and scanning techniques - at the expense of creating large data volumes. This talk will discuss solutions to these challenges, as well as an outlook towards future developments.

Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy

PubMed Central

Withers, P. J.

2015-01-01

To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored. PMID:25624521

Dark-field X-ray microscopy for multiscale structural characterization

NASA Astrophysics Data System (ADS)

Simons, H.; King, A.; Ludwig, W.; Detlefs, C.; Pantleon, W.; Schmidt, S.; Snigireva, I.; Snigirev, A.; Poulsen, H. F.

2015-01-01

Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. Here we present dark-field X-ray microscopy; a non-destructive microscopy technique for the three-dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1 mm within embedded sampling volumes. The technique, which allows ‘zooming’ in and out in both direct and angular space, is demonstrated by an annealing study of plastically deformed aluminium. Facilitating the direct study of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements (for example, positioned at interfaces) is crucial to the performance and lifetime of macro-scale devices and components thereof.

Imaging nanoscale lattice variations by machine learning of x-ray diffraction microscopy data

DOE PAGES

Laanait, Nouamane; Zhang, Zhan; Schlepütz, Christian M.

2016-08-09

In this paper, we present a novel methodology based on machine learning to extract lattice variations in crystalline materials, at the nanoscale, from an x-ray Bragg diffraction-based imaging technique. By employing a full-field microscopy setup, we capture real space images of materials, with imaging contrast determined solely by the x-ray diffracted signal. The data sets that emanate from this imaging technique are a hybrid of real space information (image spatial support) and reciprocal lattice space information (image contrast), and are intrinsically multidimensional (5D). By a judicious application of established unsupervised machine learning techniques and multivariate analysis to this multidimensional datamore » cube, we show how to extract features that can be ascribed physical interpretations in terms of common structural distortions, such as lattice tilts and dislocation arrays. Finally, we demonstrate this 'big data' approach to x-ray diffraction microscopy by identifying structural defects present in an epitaxial ferroelectric thin-film of lead zirconate titanate.« less

Imaging nanoscale lattice variations by machine learning of x-ray diffraction microscopy data

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

Laanait, Nouamane; Zhang, Zhan; Schlepütz, Christian M.

In this paper, we present a novel methodology based on machine learning to extract lattice variations in crystalline materials, at the nanoscale, from an x-ray Bragg diffraction-based imaging technique. By employing a full-field microscopy setup, we capture real space images of materials, with imaging contrast determined solely by the x-ray diffracted signal. The data sets that emanate from this imaging technique are a hybrid of real space information (image spatial support) and reciprocal lattice space information (image contrast), and are intrinsically multidimensional (5D). By a judicious application of established unsupervised machine learning techniques and multivariate analysis to this multidimensional datamore » cube, we show how to extract features that can be ascribed physical interpretations in terms of common structural distortions, such as lattice tilts and dislocation arrays. Finally, we demonstrate this 'big data' approach to x-ray diffraction microscopy by identifying structural defects present in an epitaxial ferroelectric thin-film of lead zirconate titanate.« less

3D nanoscale imaging of the yeast, Schizosaccharomyces pombe, by full-field transmission x-ray microscopy at 5.4 keV

PubMed Central

Chen, Jie; Yang, Yunhao; Zhang, Xiaobo; Andrews, Joy C.; Pianetta, Piero; Guan, Yong; Liu, Gang; Xiong, Ying; Wu, Ziyu; Tian, Yangchao

2010-01-01

Three-dimensional (3D) nanoscale structures of the fission yeast, Schizosaccharomyces pombe, can be obtained by full-field transmission hard x-ray microscopy with 30 nm resolution using synchrotron radiation sources. Sample preparation is relatively simple and the samples are portable across various imaging environments, allowing for high throughput sample screening. The yeast cells were fixed and double stained with Reynold’s lead citrate and uranyl acetate. We performed both absorption contrast and Zernike phase contrast imaging on these cells in order to test this method. The membranes, nucleus and subcellular organelles of the cells were clearly visualized using absorption contrast mode. The x-ray images of the cells could be used to study the spatial distributions of the organelles in the cells. These results show unique structural information, demonstrating that hard x-ray microscopy is a complementary method for imaging and analyzing biological samples. PMID:20349228

High-throughput multipesticides residue analysis in earthworms by the improvement of purification method: Development and application of magnetic Fe3 O4 -SiO2 nanoparticles based dispersive solid-phase extraction.

PubMed

Sun, Yuhan; Qi, Peipei; Cang, Tao; Wang, Zhiwei; Wang, Xiangyun; Yang, Xuewei; Wang, Lidong; Xu, Xiahong; Wang, Qiang; Wang, Xinquan; Zhao, Changshan

2018-06-01

As a key representative organism, earthworms can directly illustrate the influence of pesticides on environmental organisms in soil ecosystems. The present work aimed to develop a high-throughput multipesticides residue analytical method for earthworms using solid-liquid extraction with acetonitrile as the solvent and magnetic material-based dispersive solid-phase extraction for purification. Magnetic Fe 3 O 4 nanoparticles were modified with a thin silica layer to form Fe 3 O 4 -SiO 2 nanoparticles, which were fully characterized by field-emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffractometry, and vibrating sample magnetometry. The Fe 3 O 4 -SiO 2 nanoparticles were used as the separation media in dispersive solid-phase extraction with primary secondary amine and ZrO 2 as the cleanup adsorbents to eliminate matrix interferences. The amounts of nanoparticles and adsorbents were optimized for the simultaneous determination of 44 pesticides and six metabolites in earthworms by liquid chromatography with tandem mass spectrometry. The method performance was systematically validated with satisfactory results. The limits of quantification were 20 μg/kg for all analytes studied, while the recoveries of the target analytes ranged from 65.1 to 127% with relative standard deviation values lower than 15.0%. The developed method was subsequently utilized to explore the bioaccumulation of bitertanol in earthworms exposed to contaminated soil, verifying its feasibility for real sample analysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tribological properties of thermally sprayed TiAl-Al2O3 composite coating

NASA Astrophysics Data System (ADS)

Salman, A.; Gabbitas, B.; Li, J.; Zhang, D.

2009-08-01

The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

In Situ Identification of Mineral Resources with an X-Ray-Optical "Hands-Lens" Instrument

NASA Technical Reports Server (NTRS)

Marshall, J.; Koppel, L.; Bratton, C.; Metzger, E.; Hecht, M.

1999-01-01

The recognition of material resources on a planetary surface requires exploration strategies not dissimilar to those employed by early field geologists who searched for ore deposits primarily from surface clues. In order to determine the location of mineral ores or other materials, it will be necessary to characterize host terranes at regional or subregional scales. This requires geographically broad surveys in which statistically significant numbers of samples are rapidly scanned from a roving platform. To enable broad-scale, yet power-conservative planetary-surface exploration, we are developing an instrument that combines x-ray diffractometry (XRD), x-ray fluorescence spectrometry (XRF), and optical capabilities; the instrument can be deployed at the end of a rover's robotic arm, without the need for sample capture or preparation. The instrument provides XRD data for identification of mineral species and lithological types; diffractometry of minerals is conducted by ascertaining the characteristic lattice parameters or "d-spacings" of mineral compounds. D-spacings of 1.4 to 25 angstroms can be determined to include the large molecular structures of hydrated minerals such as clays. The XRF data will identify elements ranging from carbon (Atomic Number = 6) to elements as heavy as barium (Atomic Number = 56). While a sample is being x-rayed, the instrument simultaneously acquires an optical image of the sample surface at magnifications from lx to at least 50x (200x being feasible, depending on the sample surface). We believe that imaging the sample is extremely important as corroborative sample-identification data (the need for this capability having been illustrated by the experience of the Pathfinder rover). Very few geologists would rely on instrument data for sample identification without having seen the sample. Visual inspection provides critical recognition data such as texture, crystallinity, granularity, porosity, vesicularity, color, lustre, opacity, and so forth. These data can immediately distinguish sedimentary from igneous rocks, for example, and can thus eliminate geochemical or mineral ambiguities arising, say between arkose and granite. It would be important to know if the clay being analyzed was part of a uniform varve deposit laid down in a quiescent lake, or the matrix of a megabreccia diamictite deposited as a catastrophic impact ejecta blanket. The unique design of the instrument, which combines Debye-Scherrer geometry with elements of standard goniometry, negates the need for sample preparation of any kind, and thus negates the need for power-hungry and mechanically-complex sampling systems that would have to chip, crush, sieve, and mount the sample for x-ray analysis. Instead, the instrument is simply rested on the sample surface of interest (like a hand lens); the device can interrogate rough rock surfaces, coarse granular material, or fine rock flour. A breadboard version of the instrument has been deployed from the robotic arm of the Marsokhod rover in field trials at NASA Ames, where large vesicular boulders were x-rayed to demonstrate the functionality of the instrument design, and the ability of such a device to comply with constraints imposed by a roving platform. Currently under development is a flight prototype concept of this instrument that will weigh 0.3 kg, using about 4500 J of energy per sample analysis. It requires about 5 min. for XRD analysis, and about 30 min. for XRF interrogation. Its small mass and rugged design make it ideal for deployment on small rovers of the type currently envisaged for the exploration of Mars (e.g., Sojourner-scale platforms). The design utilizes a monolithic P-N junction photodiode pixel array for XRD, a Si PIN photodiode/avalanche photodiode system for XRF, and an endoscopic imaging camera system unobtrusively embedded between the detectors and the x-ray source (the endoscope with its board-mounted camera can be adapted for IR light in addition to visible wavelenths. A rugged, miniature (7 cu cm) x-ray source for the instrument has already been breadboarded.

In Situ Identification of Mineral Resources with an X-Ray-Optical "Hands-Lens" Instrument

NASA Astrophysics Data System (ADS)

Marshall, J.; Koppel, L.; Bratton, C.; Metzger, E.; Hecht, M.

1999-09-01

The recognition of material resources on a planetary surface requires exploration strategies not dissimilar to those employed by early field geologists who searched for ore deposits primarily from surface clues. In order to determine the location of mineral ores or other materials, it will be necessary to characterize host terranes at regional or subregional scales. This requires geographically broad surveys in which statistically significant numbers of samples are rapidly scanned from a roving platform. To enable broad-scale, yet power-conservative planetary-surface exploration, we are developing an instrument that combines x-ray diffractometry (XRD), x-ray fluorescence spectrometry (XRF), and optical capabilities; the instrument can be deployed at the end of a rover's robotic arm, without the need for sample capture or preparation. The instrument provides XRD data for identification of mineral species and lithological types; diffractometry of minerals is conducted by ascertaining the characteristic lattice parameters or "d-spacings" of mineral compounds. D-spacings of 1.4 to 25 angstroms can be determined to include the large molecular structures of hydrated minerals such as clays. The XRF data will identify elements ranging from carbon (Atomic Number = 6) to elements as heavy as barium (Atomic Number = 56). While a sample is being x-rayed, the instrument simultaneously acquires an optical image of the sample surface at magnifications from lx to at least 50x (200x being feasible, depending on the sample surface). We believe that imaging the sample is extremely important as corroborative sample-identification data (the need for this capability having been illustrated by the experience of the Pathfinder rover). Very few geologists would rely on instrument data for sample identification without having seen the sample. Visual inspection provides critical recognition data such as texture, crystallinity, granularity, porosity, vesicularity, color, lustre, opacity, and so forth. These data can immediately distinguish sedimentary from igneous rocks, for example, and can thus eliminate geochemical or mineral ambiguities arising, say between arkose and granite. It would be important to know if the clay being analyzed was part of a uniform varve deposit laid down in a quiescent lake, or the matrix of a megabreccia diamictite deposited as a catastrophic impact ejecta blanket. The unique design of the instrument, which combines Debye-Scherrer geometry with elements of standard goniometry, negates the need for sample preparation of any kind, and thus negates the need for power-hungry and mechanically-complex sampling systems that would have to chip, crush, sieve, and mount the sample for x-ray analysis. Instead, the instrument is simply rested on the sample surface of interest (like a hand lens); the device can interrogate rough rock surfaces, coarse granular material, or fine rock flour. A breadboard version of the instrument has been deployed from the robotic arm of the Marsokhod rover in field trials at NASA Ames, where large vesicular boulders were x-rayed to demonstrate the functionality of the instrument design, and the ability of such a device to comply with constraints imposed by a roving platform. Currently under development is a flight prototype concept of this instrument that will weigh 0.3 kg, using about 4500 J of energy per sample analysis. It requires about 5 min. for XRD analysis, and about 30 min. for XRF interrogation. Its small mass and rugged design make it ideal for deployment on small rovers of the type currently envisaged for the exploration of Mars (e.g., Sojourner-scale platforms). The design utilizes a monolithic P-N junction photodiode pixel array for XRD, a Si PIN photodiode/avalanche photodiode system for XRF, and an endoscopic imaging camera system unobtrusively embedded between the detectors and the x-ray source (the endoscope with its board-mounted camera can be adapted for IR light in addition to visible wavelenths. A rugged, miniature (7 cu cm) x-ray source for the instrument has already been breadboarded.

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

PubMed Central

Pradhan, Puja; Aryal, Puruswottam; Attygalle, Dinesh; Ibdah, Abdel-Rahman; Koirala, Prakash; Li, Jian; Bhandari, Khagendra P.; Liyanage, Geethika K.; Ellingson, Randy J.; Heben, Michael J.; Marsillac, Sylvain; Collins, Robert W.; Podraza, Nikolas J.

2018-01-01

Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In1−xGax)2Se3 (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε1 − iε2, spectra. Here, RTSE has been used to obtain the (ε1, ε2) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents (x) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε1, ε2) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x. From the resulting database of polynomial coefficients, the (ε1, ε2) spectra can be generated for any composition of IGS from the single parameter, x. The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε1, ε2) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control. PMID:29337931

Synchrotron-based X-ray Fluorescence Microscopy in Conjunction with Nanoindentation to Study Molecular-Scale Interactions of Phenol–Formaldehyde in Wood Cell Walls

Treesearch

Joseph E. Jakes; Christopher G. Hunt; Daniel J. Yelle; Linda Lorenz; Kolby Hirth; Sophie-Charlotte Gleber; Stefan Vogt; Warren Grigsby; Charles R. Frihart

2015-01-01

Understanding and controlling molecular-scale interactions between adhesives and wood polymers are critical to accelerate the development of improved adhesives for advanced wood-based materials. The submicrometer resolution of synchrotron-based X-ray fluorescence microscopy (XFM) was found capable of mapping and quantifying infiltration of Br-labeled phenol−...

High-Resolution Detector For X-Ray Diffraction

NASA Technical Reports Server (NTRS)

Carter, Daniel C.; Withrow, William K.; Pusey, Marc L.; Yost, Vaughn H.

1988-01-01

Proposed x-ray-sensitive imaging detector offers superior spatial resolution, counting-rate capacity, and dynamic range. Instrument based on laser-stimulated luminescence and reusable x-ray-sensitive film. Detector scans x-ray film line by line. Extracts latent image in film and simultaneously erases film for reuse. Used primarily for protein crystallography. Principle adapted to imaging detectors for electron microscopy and fluorescence spectroscopy and general use in astronomy, engineering, and medicine.

Time-Resolved, High-Resolution, X-Ray Microscopy of In-Vitro Biological and Life Science Specimens with the Aid of Laser Plasmas

DTIC Science & Technology

1994-06-30

transmissive Fresnel lens. We have made considerable effort in the last few years to explore the potential of x-ray multilayer-coated Schwarzschild x-ray...ray mirror fabrication and efficient x-ray mirror design. A 120mm diameter, NA = 0.35, 15X Schwarzschild microscope coated with Ni/C multilayer mios for...et al 2 developed a smaller, 33mm diameter, NA - 0.28, 15X Schwarzschild microscope coated with a W/C multilayer mirror for 4.4nm, in the socalled

X-ray induced chemical reaction revealed by in-situ X-ray diffraction and scanning X-ray microscopy in 15 nm resolution (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ge, Mingyuan; Liu, Wenjun; Bock, David; De Andrade, Vincent; Yan, Hanfei; Huang, Xiaojing; Marschilok, Amy; Takeuchi, Esther; Xin, Huolin; Chu, Yong S.

2016-09-01

The detection sensitivity of synchrotron-based X-ray techniques has been largely improved due to the ever increasing source brightness, which have significantly advanced ex-situ and in-situ research for energy materials, such as lithium-ion batteries. However, the strong beam-matter interaction arisen from the high beam flux can significantly modify the material structure. The parasitic beam-induced effect inevitably interferes with the intrinsic material property, which brings difficulties in interpreting experimental results, and therefore requires comprehensive evaluation. Here we present a quantitative in-situ study of the beam-effect on one electrode material Ag2VO2PO4 using four different X-ray probes with different radiation dose rate. The material system we reported exhibits interesting and reversible radiation-induced thermal and chemical reactions, which was further evaluated under electron microscopy to illustrate the underlying mechanism. The work we presented here will provide a guideline in using synchrotron X-rays to distinguish the materials' intrinsic behavior from extrinsic structure changed induced by X-rays, especially in the case of in-situ and operando study where the materials are under external field of either temperature or electric field.

Contrast enhancement of biological nanoporous materials with zinc oxide infiltration for electron and X-ray nanoscale microscopy

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

Ocola, L. E.; Sampathkumar, V.; Kasthuri, N.

Here, we show that using infiltration of ZnO metal oxide can be useful for high resolution imaging of biological samples in electron and X-ray microscopy. This method is compatible with standard fixation techniques that leave the sample dry, such as finishing with super critical CO 2 drying, or simple vacuum drying at 95°C. We demonstrate this technique can be applied on tooth and brain tissue samples. We also show that high resolution X-ray tomography can be performed on biological systems using Zn K edge (1s) absorption to enhance internal structures, and obtained the first nanoscale 10 KeV X-ray absorption imagesmore » of the interior regions of a tooth.« less

Contrast enhancement of biological nanoporous materials with zinc oxide infiltration for electron and X-ray nanoscale microscopy

DOE PAGES

Ocola, L. E.; Sampathkumar, V.; Kasthuri, N.; ...

2017-07-19

Here, we show that using infiltration of ZnO metal oxide can be useful for high resolution imaging of biological samples in electron and X-ray microscopy. This method is compatible with standard fixation techniques that leave the sample dry, such as finishing with super critical CO 2 drying, or simple vacuum drying at 95°C. We demonstrate this technique can be applied on tooth and brain tissue samples. We also show that high resolution X-ray tomography can be performed on biological systems using Zn K edge (1s) absorption to enhance internal structures, and obtained the first nanoscale 10 KeV X-ray absorption imagesmore » of the interior regions of a tooth.« less

An instrument for 3D x-ray nano-imaging

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

Holler, M.; Raabe, J.; Diaz, A.

We present an instrument dedicated to 3D scanning x-ray microscopy, allowing a sample to be precisely scanned through a beam while the angle of x-ray incidence can be changed. The position of the sample is controlled with respect to the beam-defining optics by laser interferometry. The instrument achieves a position stability better than 10 nm standard deviation. The instrument performance is assessed using scanning x-ray diffraction microscopy and we demonstrate a resolution of 18 nm in 2D imaging of a lithographic test pattern while the beam was defined by a pinhole of 3 {mu}m in diameter. In 3D on amore » test object of copper interconnects of a microprocessor, a resolution of 53 nm is achieved.« less

Picosecond excimer laser-plasma x-ray source for microscopy, biochemistry, and lithography

NASA Astrophysics Data System (ADS)

Turcu, I. C. Edmond; Ross, Ian N.; Trenda, P.; Wharton, C. W.; Meldrum, R. A.; Daido, Hiroyuki; Schulz, M. S.; Fluck, P.; Michette, Alan G.; Juna, A. P.; Maldonado, Juan R.; Shields, Harry; Tallents, Gregory J.; Dwivedi, L.; Krishnan, J.; Stevens, D. L.; Jenner, T.; Batani, Dimitri; Goodson, H.

1994-02-01

At Rutherford Appleton Laboratory we developed a high repetition rate, picosecond, excimer laser system which generates a high temperature and density plasma source emitting approximately 200 mW (78 mW/sr) x ray average power at h(nu) approximately 1.2 KeV or 0.28 KeV < h(nu) < 0.53 KeV (the `water window'). At 3.37 nm wavelength the spectral brightness of the source is approximately 9 X 1011 photons/s/mm2/mrad2/0.1% bandwidth. The x-ray source serves a large user community for applications such as: scanning and holographic microscopy, the study of the biochemistry of DNA damage and repair, microlithography and spectroscopy.

Anisotropic magnetic properties of the KMo4O6

NASA Astrophysics Data System (ADS)

Andrade, M.; Maffei, M. L.; Dos Santos, C. A. M.; Ferreira, B.; Sartori, A. F.

2012-02-01

Electrical resistivity measurements in the tetragonal KMo4O6 single crystals show a metal-insulator transition (MIT) near 100K. Magnetization measurements as a function of temperature show no evidence of magnetic ordering at this MIT [1]. Single crystals of KMo4O6 were obtained by electrolysis of a melt with a molar ratio of K2MoO4:MoO3 = 6:1. The process were carried out at 930 C with a current of 20-25mA for 52h in argon atmosphere. After that, electrodes were removed from the melt alloying the crystals to cool down to room temperature rapidly. Scanning Electron Microscopy (SEM) showed that the black single crystals were grown on the platinum cathode. Typical dimensions of the single crystals are 1x0.2x0.2mm^3. X-ray diffractometry confirmed that the single crystals have KMo4O6 tetragonal crystalline structure with space group P4. Magnetization measurements were performed parallel and perpendicular to the c-axis from 2 to 300K. The results show anisotropic behavior between both directions. Furthermore, the temperature independence of the magnetization at high temperature and the upturn at low temperature are observed in agreement with previous results [1]. MxH curves measured at several temperatures show nonlinear behavior and a small magnetic ordering. The magnetic ordering seems to be related to the MIT near 100K. This material is based upon support by FAPESP (2009/14524-6 and 2009/54001-6) and CNPq/NSF (490182/2009-7). M. Andrade is CAPES fellow and C.A.M. dos Santos is CNPq fellow. [4pt] [1] K. V. Ramanujachary et al., J. Sol. State Chem.102 (1993) 69.

National Synchrotron Light Source annual report 1991

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

Hulbert, S.L.; Lazarz, N.M.

1992-04-01

This report discusses the following research conducted at NSLS: atomic and molecular science; energy dispersive diffraction; lithography, microscopy and tomography; nuclear physics; UV photoemission and surface science; x-ray absorption spectroscopy; x-ray scattering and crystallography; x-ray topography; workshop on surface structure; workshop on electronic and chemical phenomena at surfaces; workshop on imaging; UV FEL machine reviews; VUV machine operations; VUV beamline operations; VUV storage ring parameters; x-ray machine operations; x-ray beamline operations; x-ray storage ring parameters; superconducting x-ray lithography source; SXLS storage ring parameters; the accelerator test facility; proposed UV-FEL user facility at the NSLS; global orbit feedback systems; and NSLSmore » computer system.« less

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

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

Deng, Junjing; Vine, David J.; Chen, Si

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolutionmore » beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ~90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. Finally, this combined approach offers a way to study the role of trace elements in their structural context.« less

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

DOE PAGES

Deng, Junjing; Vine, David J.; Chen, Si; ...

2015-02-24

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolutionmore » beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and ~90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. Finally, this combined approach offers a way to study the role of trace elements in their structural context.« less

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

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

Deng, Junjing; Vine, David J.; Chen, Si

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolutionmore » beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and similar to 90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context.« less

Synchrotron-based X-ray microscopic studies for bioeffects of nanomaterials.

PubMed

Zhu, Ying; Cai, Xiaoqing; Li, Jiang; Zhong, Zengtao; Huang, Qing; Fan, Chunhai

2014-04-01

There have been increasing interests in studying biological effects of nanomaterials, which are nevertheless faced up with many challenges due to the nanoscale dimensions and unique chemical properties of nanomaterials. Synchrotron-based X-ray microscopy, an advanced imaging technology with high spatial resolution and excellent elemental specificity, provides a new platform for studying interactions between nanomaterials and living systems. In this article, we review the recent progress of X-ray microscopic studies on bioeffects of nanomaterials in several living systems including cells, model organisms, animals and plants. We aim to provide an overview of the state of the art, and the advantages of using synchrotron-based X-ray microscopy for characterizing in vitro and in vivo behaviors and biodistribution of nanomaterials. We also expect that the use of a combination of new synchrotron techniques should offer unprecedented opportunities for better understanding complex interactions at the nano-biological interface and accounting for unique bioeffects of nanomaterials. Synchrotron-based X-ray microscopy is a non-destructive imaging technique that enables high resolution spatial mapping of metals with elemental level detection methods. This review summarizes the current use and perspectives of this novel technique in studying the biology and tissue interactions of nanomaterials. Copyright © 2014 Elsevier Inc. All rights reserved.

Apparatus for X-ray diffraction microscopy and tomography of cryo specimens

DOE PAGES

Beetz, T.; Howells, M. R.; Jacobsen, C.; ...

2005-03-14

An apparatus for diffraction microscopy of biological and materials science specimens is described. In this system, a coherent soft X-ray beam is selected with a pinhole, and the illuminated specimen is followed by an adjustable beamstop and CCD camera to record diffraction data from non-crystalline specimens. In addition, a Fresnel zone plate can be inserted to allow for direct imaging. The system makes use of a cryogenic specimen holder with cryotransfer capabilities to allow frozen hydrated specimens to be loaded. The specimen can be tilted over a range of ± 80 ° degrees for three-dimensional imaging; this is done bymore » computer-controlled motors, enabling automated alignment of the specimen through a tilt series. The system is now in use for experiments in soft X-ray diffraction microscopy.« less

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

Deng, Junjing; Vine, David J.; Chen, Si

X-ray microscopy can be used to image whole, unsectioned cells in their native hydrated state. It complements the higher resolution of electron microscopy for submicrometer thick specimens, and the molecule-specific imaging capabilites of fluorescence light microscopy. We describe here the first use of fast, continuous x-ray scanning of frozen hydrated cells for simultaneous sub-20 nm resolution ptychographic transmission imaging with high contrast, and sub-100 nm resolution deconvolved x-ray fluorescence imaging of diffusible and bound ions at native concentrations, without the need to add specific labels. Here, by working with cells that have been rapidly frozen without the use of chemicalmore » fixatives, and imaging them under cryogenic conditions, we are able to obtain images with well preserved structural and chemical composition, and sufficient stability against radiation damage to allow for multiple images to be obtained with no observable change.« less

Some radiation effects on organic binders in X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Novosel-Radović, Vj.; MaljkoviĆ, Da.; NenadiĆ, N.

The paper deals with diminished wear resistance of standard samples in X-ray fluorescence spectrometry. The effect of X-ray irradiation on pellet samples, pressed with starch as organic binder, was investigated by sieve analysis and scanning electron microscopy. A change in the starch grain size was found as a result of swelling and cracking.

Laser-induced Multi-energy Processing in Diamond Growth

DTIC Science & Technology

2012-05-01

microscopy (SEM) and energy dispersive X - ray (EDX) measurements, Drs. Yi Liu and Shah Valloppilly from Nebraska Center for Materials and Nanoscience...NCMN) at UNL for help on X - Ray diffraction (XRD) measurements, and Professor Steve W. Martin and Dr. Young Sik Kim from the Department of Material...spectroscopy and X - ray diffraction ................... 62 4.4 Conclusions

X-ray/EUV optics for astronomy, microscopy, polarimetry, and projection lithography; Proceedings of the Meeting, San Diego, CA, July 9-13, 1990

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Editor); Walker, Arthur B. C., Jr. (Editor)

1991-01-01

Topics discussed in this issue include the fabrication of multilayer X-ray/EUV coatings; the design, characterization, and test of multilayer X-ray/EUV coatings; multilayer X-ray/EUV monochromators and imaging microscopes; X-ray/EUV telescopes; the test and calibration performance of X-ray/EUV instruments; XUV/soft X-ray projection lithography; X-ray/EUV space observatories and missions; X-ray/EUV telescopes for solar research; X-ray/EUV polarimetry; X-ray/EUV spectrographs; and X-ray/EUV filters and gratings. Papers are presented on the deposition-controlled uniformity of multilayer mirrors, interfaces in Mo/Si multilayers, the design and analysis of an aspherical multilayer imaging X-ray microscope, recent developments in the production of thin X-ray reflecting foils, and the ultraprecise scanning technology. Consideration is also given to an active sun telescope array, the fabrication and performance at 1.33 nm of a 0.24-micron-period multilayer grating, a cylindrical proportional counter for X-ray polarimetry, and the design and analysis of the reflection grating arrays for the X-Ray Multi-Mirror Mission.

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

Stuckelberger, Michael; West, Bradley; Nietzold, Tara

In situ and operando measurement techniques combined with nanoscale resolution have proven invaluable in multiple fields of study. We argue that evaluating device performance as well as material behavior by correlative X-ray microscopy with <100 nm resolution can radically change the approach for optimizing absorbers, interfaces and full devices in solar cell research. Here, we thoroughly discuss the measurement technique of X-ray beam induced current and point out fundamental differences between measurements of wafer-based silicon and thin-film solar cells. Based on reports of the last years, we showcase the potential that X-ray microscopy measurements have in combination with in situmore » and operando approaches throughout the solar cell lifecycle: from the growth of individual layers to the performance under operating conditions and degradation mechanisms. Enabled by new developments in synchrotron beamlines, the combination of high spatial resolution with high brilliance and a safe working distance allows for the insertion of measurement equipment that can pave the way for a new class of experiments. When applied to photovoltaics research, we highlight today’s opportunities and challenges in the field of nanoscale X-ray microscopy, and give an outlook on future developments.« less

Cryogenic coherent X-ray diffraction imaging of biological samples at SACLA: a correlative approach with cryo-electron and light microscopy.

PubMed

Takayama, Yuki; Yonekura, Koji

2016-03-01

Coherent X-ray diffraction imaging at cryogenic temperature (cryo-CXDI) allows the analysis of internal structures of unstained, non-crystalline, whole biological samples in micrometre to sub-micrometre dimensions. Targets include cells and cell organelles. This approach involves preparing frozen-hydrated samples under controlled humidity, transferring the samples to a cryo-stage inside a vacuum chamber of a diffractometer, and then exposing the samples to coherent X-rays. Since 2012, cryo-coherent diffraction imaging (CDI) experiments have been carried out with the X-ray free-electron laser (XFEL) at the SPring-8 Ångstrom Compact free-electron LAser (SACLA) facility in Japan. Complementary use of cryo-electron microscopy and/or light microscopy is highly beneficial for both pre-checking samples and studying the integrity or nature of the sample. This article reports the authors' experience in cryo-XFEL-CDI of biological cells and organelles at SACLA, and describes an attempt towards reliable and higher-resolution reconstructions, including signal enhancement with strong scatterers and Patterson-search phasing.

Signal-to-noise and radiation exposure considerations in conventional and diffraction x-ray microscopy

DOE PAGES

Huang, Xiaojing; Miao, Huijie; Steinbrener, Jan; ...

2009-01-01

Using a signal-to-noise ratio estimation based on correlations between multiple simulated images, we compare the dose efficiency of two soft x-ray imaging systems: incoherent brightfield imaging using zone plate optics in a transmission x-ray microscope (TXM), and x-ray diffraction microscopy (XDM) where an image is reconstructed from the far-field coherent diffraction pattern. In XDM one must computationally phase weak diffraction signals; in TXM one suffers signal losses due to the finite numerical aperture and efficiency of the optics. In simulations with objects representing isolated cells such as yeast, we find that XDM has the potential for delivering equivalent resolution imagesmore » using fewer photons. As a result, this can be an important advantage for studying radiation-sensitive biological and soft matter specimens.« less

An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy.

PubMed

Wang, Kangkang; Rosenmann, Daniel; Holt, Martin; Winarski, Robert; Hla, Saw-Wai; Rose, Volker

2013-06-01

In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements of topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.

The use of radiation for the study of material of cultural heritage significance

NASA Astrophysics Data System (ADS)

Creagh, D. C.; Otieno-Alego, V.

2004-01-01

For the indigenous people of Northern Australia the expression of their experience of life, their "dreaming", is in the form of painting, usually on the bark stripped from trees growing in their tribal lands. These are often works of great beauty and the major collecting institutions in Australia and elsewhere have significant holdings of Aboriginal bark paintings. A wide range of analytical techniques (optical microscopy, FTIR microscopy, Raman microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, and synchrotron radiation X-ray diffraction) has been used in a project to determine how best to conserve Aboriginal bark paintings.

Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

NASA Technical Reports Server (NTRS)

Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

2015-01-01

Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

Proteomic analysis of a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate: a case report.

PubMed

Kaneko, Kiyoko; Matsuta, Yosuke; Moriyama, Manabu; Yasuda, Makoto; Chishima, Noriharu; Yamaoka, Noriko; Fukuuchi, Tomoko; Miyazawa, Katsuhito; Suzuki, Koji

2014-03-01

The objective of the present study was to investigate the matrix protein of a rare urinary stone that contained calcium carbonate. A urinary stone was extracted from a 34-year-old male patient with metabolic alkalosis. After X-ray diffractometry and infrared analysis of the stone, proteomic analysis was carried out. The resulting mass spectra were evaluated with protein search software, and matrix proteins were identified. X-ray diffraction and infrared analysis confirmed that the stone contained calcium carbonate and calcium oxalate dihydrate. Of the identified 53 proteins, 24 have not been previously reported from calcium oxalate- or calcium phosphate-containing stones. The protease inhibitors and several proteins related to cell adhesion or the cytoskeleton were identified for the first time. We analyzed in detail a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate. Considering the formation of a calcium carbonate stone, the new identified proteins should play an important role on the urolithiasis process in alkaline condition. © 2013 The Japanese Urological Association.

Uncommon and Emissive {[Au2(C3H6NS2)2][Au(C3H6NS2)2]2(PF6)2} Mixed Au+ and Au3+ Pseudotetranuclear Crystalline Compound: Synthesis, Structural Characterization, and Optical Properties.

PubMed

Langaro, Ana P; Souza, Ana K R; Morassuti, Claudio Y; Lima, Sandro M; Casagrande, Gleison A; Deflon, Victor M; Nunes, Luiz A O; Da Cunha Andrade, Luis H

2016-11-23

An uncommon emissive pseudotetranuclear compound, {[Au 2 (C 3 H 6 NS 2 ) 2 ][Au(C 3 H 6 NS 2 ) 2 ] 2 (PF 6 ) 2 }, was synthesized and characterized in terms of its structure and optical properties. The synthesis produced a crystalline compound composed of four gold atoms with two different oxidation states (Au + and Au 3+ ) in the same crystalline structure. The title complex belonged to a triclinic crystalline system involving the centrosymmetric P1̅ space group. X-ray diffractometry and vibrational spectroscopy (infrared, Raman, and SERS) were used for structural characterization of the new crystal. The vibrational spectroscopy techniques supported the X-ray diffraction results and confirmed the presence of bonds including Au-Au and Au-S. Optical characterization performed using UV-vis spectroscopy showed that under ultraviolet excitation, the emissive crystalline complex presented characteristic broad luminescent bands centered at 420 and 670 nm.

Crystal structure and thermal expansion of a CsCe 2Cl 7 scintillator

DOE PAGES

Zhuravleva, M.; Lindsey, A.; Chakoumakos, B. C.; ...

2015-04-06

Here we used single-crystal X-ray diffraction data to determine crystal structure of CsCe 2Cl 7. It crystallizes in a P112 1/b space group with a = 19.352(1) Å, b = 19.352(1) Å, c = 14.838(1) Å, γ = 119.87(2) ° , and V = 4818.6(5) Å 3. Differential scanning calorimetry measurements combined with the structural evolution of CsCe 2Cl 7 via X-ray diffractometry over a temperature range from room temperature to the melting point indicates no obvious intermediate solid-solid phase transitions. The anisotropy in the average linear coefficient of thermal expansion of the a axis (21.3 10 -6/ °C) withmore » respect to the b and c axes (27.0 10 -6/ °C) was determined through lattice parameter refinement of the temperature dependent diffraction patterns. Lastly, these findings suggest that the reported cracking behavior during melt growth of CsCe 2Cl 7 bulk crystals using conventional Bridgman and Czochralski techniques may be largely attributed to the anisotropy in thermal expansion.« less

Behavior of pure gallium in water and various saline solutions.

PubMed

Horasawa, N; Nakajima, H; Takahashi, S; Okabe, T

1997-12-01

This study investigated the chemical stability of pure gallium in water and saline solutions in order to obtain fundamental knowledge about the corrosion mechanism of gallium-based alloys. A pure gallium plate (99.999%) was suspended in 50 mL of deionized water, 0.01%, 0.1% or 1% NaCl solution at 24 +/- 2 degrees C for 1, 7, or 28 days. The amounts of gallium released into the solutions were determined by atomic absorption spectrophotometry. The surfaces of the specimens were examined after immersion by x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). In the solutions containing 0.1% or more NaCl, the release of gallium ions into the solution was lowered when compared to deionized water after 28-day immersion. Gallium oxide monohydroxide was found by XRD on the specimens immersed in deionized water after 28-day immersion. XPS indicated the formation of gallium oxide/hydroxide on the specimens immersed in water or 0.01% NaCl solution. The chemical stability of pure solid gallium was strongly affected by the presence of Cl- ions in the aqueous solution.

Soft X-Ray Microscopy Radiation Damage On Fixed Cells Investigated With Synchrotron Radiation FTIR Microscopy.

PubMed

Gianoncelli, A; Vaccari, L; Kourousias, G; Cassese, D; Bedolla, D E; Kenig, S; Storici, P; Lazzarino, M; Kiskinova, M

2015-05-14

Radiation damage of biological samples remains a limiting factor in high resolution X-ray microscopy (XRM). Several studies have attempted to evaluate the extent and the effects of radiation damage, proposing strategies to minimise or prevent it. The present work aims to assess the impact of soft X-rays on formalin fixed cells on a systematic manner. The novelty of this approach resides on investigating the radiation damage not only with XRM, as often reported in relevant literature on the topic, but by coupling it with two additional independent non-destructive microscopy methods: Atomic Force Microscopy (AFM) and FTIR Microscopy (FTIRM). Human Embryonic Kidney 293 cells were exposed to different radiation doses at 1 keV. In order to reveal possible morphological and biochemical changes, the irradiated cells were systematically analysed with AFM and FTIRM before and after. Results reveal that while cell morphology is not substantially affected, cellular biochemical profile changes significantly and progressively when increasing dose, resulting in a severe breakdown of the covalent bonding network. This information impacts most soft XRM studies on fixed cells and adds an in-depth understanding of the radiation damage for developing better prevention strategies.

Soft X-Ray Microscopy Radiation Damage On Fixed Cells Investigated With Synchrotron Radiation FTIR Microscopy

PubMed Central

Gianoncelli, A.; Vaccari, L.; Kourousias, G.; Cassese, D.; Bedolla, D. E.; Kenig, S.; Storici, P.; Lazzarino, M.; Kiskinova, M.

2015-01-01

Radiation damage of biological samples remains a limiting factor in high resolution X-ray microscopy (XRM). Several studies have attempted to evaluate the extent and the effects of radiation damage, proposing strategies to minimise or prevent it. The present work aims to assess the impact of soft X-rays on formalin fixed cells on a systematic manner. The novelty of this approach resides on investigating the radiation damage not only with XRM, as often reported in relevant literature on the topic, but by coupling it with two additional independent non-destructive microscopy methods: Atomic Force Microscopy (AFM) and FTIR Microscopy (FTIRM). Human Embryonic Kidney 293 cells were exposed to different radiation doses at 1 keV. In order to reveal possible morphological and biochemical changes, the irradiated cells were systematically analysed with AFM and FTIRM before and after. Results reveal that while cell morphology is not substantially affected, cellular biochemical profile changes significantly and progressively when increasing dose, resulting in a severe breakdown of the covalent bonding network. This information impacts most soft XRM studies on fixed cells and adds an in-depth understanding of the radiation damage for developing better prevention strategies. PMID:25974639

Multimodal imaging of human cerebellum - merging X-ray phase microtomography, magnetic resonance microscopy and histology

NASA Astrophysics Data System (ADS)

Schulz, Georg; Waschkies, Conny; Pfeiffer, Franz; Zanette, Irene; Weitkamp, Timm; David, Christian; Müller, Bert

2012-11-01

Imaging modalities including magnetic resonance imaging and X-ray computed tomography are established methods in daily clinical diagnosis of human brain. Clinical equipment does not provide sufficient spatial resolution to obtain morphological information on the cellular level, essential for applying minimally or non-invasive surgical interventions. Therefore, generic data with lateral sub-micrometer resolution have been generated from histological slices post mortem. Sub-cellular spatial resolution, lost in the third dimension as a result of sectioning, is obtained using magnetic resonance microscopy and micro computed tomography. We demonstrate that for human cerebellum grating-based X-ray phase tomography shows complementary contrast to magnetic resonance microscopy and histology. In this study, the contrast-to-noise values of magnetic resonance microscopy and phase tomography were comparable whereas the spatial resolution in phase tomography is an order of magnitude better. The registered data with their complementary information permit the distinct segmentation of tissues within the human cerebellum.

Synergic Investigation Of The Self-Assembly Structure And Mechanism Of Retroviral Capsid Proteins By Solid State NMR, Transmission Electron Microscopy And Multiscale simulation

DTIC Science & Technology

2017-03-29

310 helix. Green: this work. Cyans: solution NMR RSV CA structure in PDB entry 1D1D.[18] Magentas: X-ray crystallography structure of flat hexameric...to combine cryo-electron microscopy and X-ray crystallography , Methods, 49 (2009) 174-180. [8] K.Y. Chan, J. Gumbart, R. McGreevy, J.M. Watermeyer

Investigation of nanoparticulate silicon as printed layers using scanning electron microscopy, transmission electron microscopy, X-ray absorption spectroscopy and X-ray photoelectron spectroscopy

DOE PAGES

Unuigbe, David M.; Harting, Margit; Jonah, Emmanuel O.; ...

2017-08-21

The presence of native oxide on the surface of silicon nanoparticles is known to inhibit charge transport on the surfaces. Scanning electron microscopy (SEM) studies reveal that the particles in the printed silicon network have a wide range of sizes and shapes. High-resolution transmission electron microscopy reveals that the particle surfaces have mainly the (111)- and (100)-oriented planes which stabilizes against further oxidation of the particles. X-ray absorption spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) measurements at the O 1s-edge have been utilized to study the oxidation and local atomic structure of printed layers of silicon nanoparticles which were milledmore » for different times. XANES results reveal the presence of the +4 (SiO 2) oxidation state which tends towards the +2 (SiO) state for higher milling times. Si 2pXPS results indicate that the surfaces of the silicon nanoparticles in the printed layers are only partially oxidized and that all three sub-oxide, +1 (Si 2O), +2 (SiO) and +3 (Si 2O 3), states are present. The analysis of the change in the sub-oxide peaks of the silicon nanoparticles shows the dominance of the +4 state only for lower milling times.« less

Quantitative Imaging of Single Unstained Magnetotactic Bacteria by Coherent X-ray Diffraction Microscopy.

PubMed

Fan, Jiadong; Sun, Zhibin; Zhang, Jian; Huang, Qingjie; Yao, Shengkun; Zong, Yunbing; Kohmura, Yoshiki; Ishikawa, Tetsuya; Liu, Hong; Jiang, Huaidong

2015-06-16

Novel coherent diffraction microscopy provides a powerful lensless imaging method to obtain a better understanding of the microorganism at the nanoscale. Here we demonstrated quantitative imaging of intact unstained magnetotactic bacteria using coherent X-ray diffraction microscopy combined with an iterative phase retrieval algorithm. Although the signal-to-noise ratio of the X-ray diffraction pattern from single magnetotactic bacterium is weak due to low-scattering ability of biomaterials, an 18.6 nm half-period resolution of reconstructed image was achieved by using a hybrid input-output phase retrieval algorithm. On the basis of the quantitative reconstructed images, the morphology and some intracellular structures, such as nucleoid, polyβ-hydroxybutyrate granules, and magnetosomes, were identified, which were also confirmed by scanning electron microscopy and energy dispersive spectroscopy. With the benefit from the quantifiability of coherent diffraction imaging, for the first time to our knowledge, an average density of magnetotactic bacteria was calculated to be ∼1.19 g/cm(3). This technique has a wide range of applications, especially in quantitative imaging of low-scattering biomaterials and multicomponent materials at nanoscale resolution. Combined with the cryogenic technique or X-ray free electron lasers, the method could image cells in a hydrated condition, which helps to maintain their natural structure.

Characterization of (Ba(0.5)Sr(0.5)) TiO3 Thin Films for Ku-Band Phase Shifters

NASA Technical Reports Server (NTRS)

Mueller, Carl H.; VanKeuls, Fredrick W.; Romanofsky, Robert R.; Miranda, Felix A.; Warner, Joseph D.; Canedy, Chadwick L.; Ramesh, Rammamoorthy

1999-01-01

The microstructural properties of (Ba(0.5)Sr(0.5)TiO3) (BSTO) thin films (300, 700, and 1400 nm thick) deposited on LaAlO3 (LAO) substrates were characterized using high-resolution x-ray diffractometry. Film crystallinity was the parameter that most directly influenced tunability, and we observed that a) the crystalline quality was highest in the thinnest film and progressively degraded with increasing film thickness; and b) strain at the film/substrate interface was completely relieved via dislocation formation. Paraelectric films such as BSTO offer an attractive means of incorporating low-cost phase shifter circuitry into beam-steerable reflectarray antennas.

Solid-state properties and crystallization behavior of PHA-739521 polymorphs.

PubMed

Sun, Changquan Calvin

2006-08-17

PHA-739521 is an experimental compound that exhibits polymorphism. The two anhydrous crystal forms, I and II, are characterized using powder X-ray diffractometry, thermal analyses, moisture sorption gravimetry. Both Forms I and II are non-hygroscopic and are stable to compaction pressure. The melting temperature is about 152 degrees C for Form I and 168 degrees C for Form II. Forms I and II are enantiotropically related where Form I is more stable below a transition temperature of approximately 70 degrees C. Crystallization behavior of this compound from solutions and during heating is also studied. Information obtained is used to design an appropriate crystallization process to successfully manufacture desired polymorph at large scale.

Effects of W on microstructure of as-cast 28 wt.%Cr–2.6 wt.%C–(0–10)wt.%W irons

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

Imurai, S.; Thanachayanont, C.; Pearce, J.T.H.

2015-01-15

Microstructures of as-cast 28 wt.%Cr–2.6 wt.%C irons containing (0–10)wt.%W with the Cr/C ratio about 10 were studied and related to their hardness. The experimental irons were cast into dry sand molds. Microstructural investigation was performed by light microscopy, X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometry. It was found that the irons with 1 to 10 wt.%W addition was hypereutectic containing large primary M{sub 7}C{sub 3}, whereas the reference iron without W addition was hypoeutectic. The matrix in all irons was austenite, partly transformed to martensite during cooling. The volume fractions of primary M{sub 7}C{sub 3}more » and the total carbides increased, but that of eutectic carbides decreased with increasing the W content of the irons. W addition promoted the formation of W-rich M{sub 7}C{sub 3}, M{sub 6}C and M{sub 23}C{sub 6}. At about 4 wt.%W, two eutectic carbides including M{sub 7}C{sub 3} and M{sub 6}C were observed together with primary M{sub 7}C{sub 3}. At 10 wt.%W, multiple carbides including primary M{sub 7}C{sub 3}, fish-bone M{sub 23}C{sub 6}, and M{sub 6}C were observed. M{sub x}C where x = 3 or less has not been found due possibly to the high M/C ratio in the studied irons. W distribution to all carbides has been determined increasing from ca. 0.3 to 0.8 in mass fraction as the W content in the irons was increased. W addition led to an increase in Vickers macro-hardness of the irons up to 671 kgf/(mm){sup 2} (HV30/15) obtained from the iron with 10 wt.%W. The formation of primary M{sub 7}C{sub 3} and aggregates of M{sub 6}C and M{sub 23}C{sub 6} were the main reasons for hardness increase, indicating potentially improved wear performance of the as-cast irons with W addition. - Highlights: • W addition at 1 up to 10 wt.%W to Fe–28Cr–2.6C produced “hypereutectic” structure. • W addition promoted the formation of W-rich M{sub 7}C{sub 3}, M{sub 6}C and M{sub 23}C{sub 6}. • M{sub 23}C{sub 6} has higher Fe/Cr and W/Cr atm% ratios than those in M{sub 7}C{sub 3}. • Si content and high W content over about 11 atm% are characteristics of M{sub 6}C. • Primary M{sub 7}C{sub 3} and aggregates of M{sub 6}C and M{sub 23}C{sub 6} increased the alloy macro-hardness.« less

Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

NASA Astrophysics Data System (ADS)

Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

2016-03-01

Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization of the resin embedded (originally polycrystalline) silicate sample. We explore the astrophysical implications of this laboratory result as an upper limit to the effect of X-rays on the structure of cosmic silicates.

X-ray elemental mapping techniques for elucidating the ecophysiology of hyperaccumulator plants.

PubMed

van der Ent, Antony; Przybyłowicz, Wojciech J; de Jonge, Martin D; Harris, Hugh H; Ryan, Chris G; Tylko, Grzegorz; Paterson, David J; Barnabas, Alban D; Kopittke, Peter M; Mesjasz-Przybyłowicz, Jolanta

2018-04-01

Contents Summary 432 I. Introduction 433 II. Preparation of plant samples for X-ray micro-analysis 433 III. X-ray elemental mapping techniques 438 IV. X-ray data analysis 442 V. Case studies 443 VI. Conclusions 446 Acknowledgements 449 Author contributions 449 References 449 SUMMARY: Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate sample preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a sample, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on sample collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the individual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future. © 2017 University of Queensland. New Phytologist © 2017 New Phytologist Trust.

Preparation, characterization and millimetre wave attenuation performance of carbon fibers coated with nickel-wolfram-phosphorus and nickel-cobalt-wolfram- phosphorus

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

Ye, Mingquan; Li, Zhitao; Wang, Chen

2016-04-15

Highlights: • SEM, XRD, EDS and MMW attenuation performances of alloys coated CFs were studied. • Resistivity and P content in alloys were main factors on MMW attenuation property. • The weight gain of coated CFs has effects on the MMW attenuation performance. - Abstract: Carbon fibers (CFs) coated with Ni–X–P (X = W, Co–W or none) alloys were prepared by electroless plating. The morphology, crystal structure, and element composition of alloy-coated CFs were characterized by scanning electron microscopy, X-ray diffractometry, energy-dispersive spectrometry and microwave attenuation. The results showed that CFs were coated with a layer of alloy particles. Pmore » content in Ni–Co–W–P or Ni–W–P alloys was lower than that in Ni–P alloy, and coating alloy Ni–P was amorphous. After W or Co introduction, coating alloys exhibited crystal characteristics. MMW-attenuation performance analysis showed that the 3 mm wave attenuation performance of CFs/Ni–Co–W–P, CFs/Ni–W–P and CFs/Ni–P increased by 7.27 dBm, 4.88 dBm and 3.55 dBm, and the 8 mm wave attenuation effects increased by 11.61 dBm, 6.11 dBm, and 4.06 dBm respectively, compared with those of CFs. MMW-attenuation performance is attributable to the sample bulk resistivity and P content in the alloy. Moreover, an optimal weight gain value existed for the MMW-attenuation performance of alloy-coated CFs.« less

Synthesis and CO2/CH4 separation peformance of Bio-MOF-1 membranes

NASA Astrophysics Data System (ADS)

Bohrman, Joseph Allen

The separation of carbon dioxide from natural gas is of great interest from the environmental and energy perspective, respectively. From the environmental point of view, capturing CO2 effectively from power plants can have a positive impact on reducing greenhouse gas emissions. From the energy point of view, CO2 is an undesirable impurity in natural gas wells, with concentrations as high as 70%. Membrane technology can play a major role in making natural gas purification processes economically feasible. A novel membrane composed of Metal-organic-framework material Zn 8(Ad)4(BPDC)6O 2Me2NH2 (Bio-MOF-1) was designed and created to effectively separate CO2/CH4 gas mixtures. The crystalline structure, composition, and textural properties of Bio-MOF-1 membranes were confirmed through x-ray diffractometry, CHN analysis, transmission electron microscopy, adsorption measurements and BET surface area. A secondary seeded growth approach was employed to prepare these membranes on tubular stainless steel porous support. These membranes displayed high CO2 permeances (11.5x10-7 mol / m2 s Pa) and moderate CO2/CH4 separation selectivities (1.2--2.5). The observed selectivities are above the Knudsen selectivity and indicate that the separation is promoted by preferential CO2 adsorption over CH4. This preferential adsorption is attributed to the presence of adeninate amino basic sites present in the Bio-MOF-1 structure. The work demonstrated shows the feasibility of the development of a novel type of membrane that could be promising for diverse molecular gas separations.

National Synchrotron Light Source annual report 1991. Volume 1, October 1, 1990--September 30, 1991

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

Hulbert, S.L.; Lazarz, N.M.

1992-04-01

This report discusses the following research conducted at NSLS: atomic and molecular science; energy dispersive diffraction; lithography, microscopy and tomography; nuclear physics; UV photoemission and surface science; x-ray absorption spectroscopy; x-ray scattering and crystallography; x-ray topography; workshop on surface structure; workshop on electronic and chemical phenomena at surfaces; workshop on imaging; UV FEL machine reviews; VUV machine operations; VUV beamline operations; VUV storage ring parameters; x-ray machine operations; x-ray beamline operations; x-ray storage ring parameters; superconducting x-ray lithography source; SXLS storage ring parameters; the accelerator test facility; proposed UV-FEL user facility at the NSLS; global orbit feedback systems; and NSLSmore » computer system.« less

Oxidation characteristics of porous-nickel prepared by powder metallurgy and cast-nickel at 1273 K in air for total oxidation time of 100 h.

PubMed

Mohamed, Lamiaa Z; Ghanem, Wafaa A; El Kady, Omayma A; Lotfy, Mohamed M; Ahmed, Hafiz A; Elrefaie, Fawzi A

2017-11-01

The oxidation behavior of two types of inhomogeneous nickel was investigated in air at 1273 K for a total oxidation time of 100 h. The two types were porous sintered-nickel and microstructurally inhomogeneous cast-nickel. The porous-nickel samples were fabricated by compacting Ni powder followed by sintering in vacuum at 1473 K for 2 h. The oxidation kinetics of the samples was determined gravimetrically. The topography and the cross-section microstructure of each oxidized sample were observed using optical and scanning electron microscopy. X-ray diffractometry and X-ray energy dispersive analysis were used to determine the nature of the formed oxide phases. The kinetic results revealed that the porous-nickel samples had higher trend for irreproducibility. The average oxidation rate for porous- and cast-nickel samples was initially rapid, and then decreased gradually to become linear. Linear rate constants were 5.5 × 10 -8  g/cm 2  s and 3.4 × 10 -8  g/cm 2  s for the porous- and cast-nickel samples, respectively. Initially a single-porous non-adherent NiO layer was noticed on the porous- and cast-nickel samples. After a longer time of oxidation, a non-adherent duplex NiO scale was formed. The two layers of the duplex scales were different in color. NiO particles were observed in most of the pores of the porous-nickel samples. Finally, the linear oxidation kinetics and the formation of porous non-adherent duplex oxide scales on the inhomogeneous nickel substrates demonstrated that the addition of new layers of NiO occurred at the scale/metal interface due to the thermodynamically possible reaction between Ni and the molecular oxygen migrating inwardly.

Dissolution of Gold and Silver with Ammonium Thiosulfate from Mangano-Argentiferous Ores Treated in Acid-Reductive Conditions

NASA Astrophysics Data System (ADS)

Tiburcio Munive, G.; Encinas Romero, M. A.; Vazquez, V. M.; Valenzuela García, J. L.; Valenzuela Soto, A.; Coronado Lopez, J. H.

2017-10-01

A novel process was studied to extract economic metals from refractory ores that are difficult to leach with cyanide and ammonium thiosulfate, such as the well-known mangano argentiferous minerals, which are minerals of manganese, iron, and silver. The mineral under consideration originates from the tailings of the Monte del Favor, Hostotipaquillo Jalisco, Mexico. The sample was characterized by x-ray diffractometry, atomic absorption spectroscopy, scanning electron microscopy, and microanalysis by energy-dispersive x-ray spectroscopy. First, the material was passed through a 100-mesh screen, and then it was subjected to reductive leaching by varying the liquid-solid ( L/ S) ratio from 2:1 to 10:1 (observations were carried out at a ratio of 5:1, which yielded higher extraction of manganese). With H2SO4 and Na2SO3 as the reducing agents, manganese extraction of up to 96.05% was achieved during the first 3 h with a mineral head of manganese 3.58%, acid consumption of 90.74 g/L, and sulfite consumption of 25.8 g/L. The mineral was then filtered and proceeded to neutralize the acidity, reaching a pH of 8 with calcium hydroxide. Then, the material was subjected to a new leaching of gold and silver values with ammonium thiosulfate. The L/ S ratio was varied (1:1, 2:1, 3:1, 4:1), and the contact time and the concentration of ammonium thiosulfate was investigated, while controlling the pH using Ca(OH)2 and NH4Cl. An L/ S ratio of 2:1 showed the best extraction of silver (97.06%) and gold (86.66%), and the thiosulfate consumption was 10.36 g/L. The mineral head of gold and silver was 0.30 g/ton and 310 g/ton, respectively. The pH was maintained between 9.8 and 8.4, such that ammonium thiosulfate stabilized with lime, and ammonium chloride did not suffer any decomposition.

Thin Film Research. Volume 1

DTIC Science & Technology

1985-05-30

Order (FECO) ......... 23 3. X -Ray Diffraction ............................... 26 4. Transmission Electron Microscopy (TEM) ............... 26 5...remained amorphous after bombardment, as evidenced by X - ray diffraction, and showed no other changes. 0 (2) For Sb203, the crystallite size was reduced...main effect on MgF2 was the reduction in crystallite size. The films were too thir. for meaningful x - ray diffraction analysis. Durability and

Soft x-ray spectromicroscopy using compact scanning transmission x-ray microscope at the photon factory

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

Takeichi, Yasuo, E-mail: yasuo.takeichi@kek.jp; Inami, Nobuhito; Ono, Kanta

We report the stability and recent performances of a new type of scanning transmission X-ray microscopy. The optics and compact design of the microscope realized mobility and robust performance. Detailed consideration to the vibration control will be described. The insertion device upgraded to elliptical polarization undulator enabled linear dichroism and circular dichroism experiments.

X-ray structure determination using low-resolution electron microscopy maps for molecular replacement

DOE PAGES

Jackson, Ryan N.; McCoy, Airlie J.; Terwilliger, Thomas C.; ...

2015-07-30

Structures of multi-subunit macromolecular machines are primarily determined by either electron microscopy (EM) or X-ray crystallography. In many cases, a structure for a complex can be obtained at low resolution (at a coarse level of detail) with EM and at higher resolution (with finer detail) by X-ray crystallography. The integration of these two structural techniques is becoming increasingly important for generating atomic models of macromolecular complexes. A low-resolution EM image can be a powerful tool for obtaining the "phase" information that is missing from an X-ray crystallography experiment, however integration of EM and X-ray diffraction data has been technically challenging.more » Here we show a step-by-step protocol that explains how low-resolution EM maps can be placed in the crystallographic unit cell by molecular replacement, and how initial phases computed from the placed EM density are extended to high resolution by averaging maps over non-crystallographic symmetry. As the resolution gap between EM and Xray crystallography continues to narrow, the use of EM maps to help with X-ray crystal structure determination, as described in this protocol, will become increasingly effective.« less

Hybrid setup for micro- and nano-computed tomography in the hard X-ray range

NASA Astrophysics Data System (ADS)

Fella, Christian; Balles, Andreas; Hanke, Randolf; Last, Arndt; Zabler, Simon

2017-12-01

With increasing miniaturization in industry and medical technology, non-destructive testing techniques are an area of ever-increasing importance. In this framework, X-ray microscopy offers an efficient tool for the analysis, understanding, and quality assurance of microscopic samples, in particular as it allows reconstructing three-dimensional data sets of the whole sample's volume via computed tomography (CT). The following article describes a compact X-ray microscope in the hard X-ray regime around 9 keV, based on a highly brilliant liquid-metal-jet source. In comparison to commercially available instruments, it is a hybrid that works in two different modes. The first one is a micro-CT mode without optics, which uses a high-resolution detector to allow scans of samples in the millimeter range with a resolution of 1 μm. The second mode is a microscope, which contains an X-ray optical element to magnify the sample and allows resolving 150 nm features. Changing between the modes is possible without moving the sample. Thus, the instrument represents an important step towards establishing high-resolution laboratory-based multi-mode X-ray microscopy as a standard investigation method.

Imaging fully hydrated whole cells by coherent x-ray diffraction microscopy.

PubMed

Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Naitow, Hisashi; Kunishima, Naoki; Yoshida, Takashi; Ishikawa, Tetsuya; Song, Changyong

2013-03-01

Nanoscale imaging of biological specimens in their native condition is of long-standing interest, in particular with direct, high resolution views of internal structures of intact specimens, though as yet progress has been limited. Here we introduce wet coherent x-ray diffraction microscopy capable of imaging fully hydrated and unstained biological specimens. Whole cell morphologies and internal structures better than 25 nm can be clearly visualized without contrast degradation.

High resolution x-ray microtomography of biological samples: Requirements and strategies for satisfying them

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

Loo, B.W. Jr.

High resolution x-ray microscopy has been made possible in recent years primarily by two new technologies: microfabricated diffractive lenses for soft x-rays with about 30-50 nm resolution, and high brightness synchrotron x-ray sources. X-ray microscopy occupies a special niche in the array of biological microscopic imaging methods. It extends the capabilities of existing techniques mainly in two areas: a previously unachievable combination of sub-visible resolution and multi-micrometer sample size, and new contrast mechanisms. Because of the soft x-ray wavelengths used in biological imaging (about 1-4 nm), XM is intermediate in resolution between visible light and electron microscopies. Similarly, the penetrationmore » depth of soft x-rays in biological materials is such that the ideal sample thickness for XM falls in the range of 0.25 - 10 {mu}m, between that of VLM and EM. XM is therefore valuable for imaging of intermediate level ultrastructure, requiring sub-visible resolutions, in intact cells and subcellular organelles, without artifacts produced by thin sectioning. Many of the contrast producing and sample preparation techniques developed for VLM and EM also work well with XM. These include, for example, molecule specific staining by antibodies with heavy metal or fluorescent labels attached, and sectioning of both frozen and plastic embedded tissue. However, there is also a contrast mechanism unique to XM that exists naturally because a number of elemental absorption edges lie in the wavelength range used. In particular, between the oxygen and carbon absorption edges (2.3 and 4.4 nm wavelength), organic molecules absorb photons much more strongly than does water, permitting element-specific imaging of cellular structure in aqueous media, with no artifically introduced contrast agents. For three-dimensional imaging applications requiring the capabilities of XM, an obvious extension of the technique would therefore be computerized x-ray microtomography (XMT).« less

Room temperature synthesis of Cu₂O nanospheres: optical properties and thermal behavior.

PubMed

Nunes, Daniela; Santos, Lídia; Duarte, Paulo; Pimentel, Ana; Pinto, Joana V; Barquinha, Pedro; Carvalho, Patrícia A; Fortunato, Elvira; Martins, Rodrigo

2015-02-01

The present work reports a simple and easy wet chemistry synthesis of cuprous oxide (Cu2O) nanospheres at room temperature without surfactants and using different precursors. Structural characterization was carried out by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with focused ion beam and energy-dispersive X-ray spectroscopy. The optical band gaps were determined from diffuse reflectance spectroscopy. The photoluminescence behavior of the as-synthesized nanospheres showed significant differences depending on the precursors used. The Cu2O nanospheres were constituted by aggregates of nanocrystals, in which an on/off emission behavior of each individual nanocrystal was identified during transmission electron microscopy observations. The thermal behavior of the Cu2O nanospheres was investigated with in situ X-ray diffraction and differential scanning calorimetry experiments. Remarkable structural differences were observed for the nanospheres annealed in air, which turned into hollow spherical structures surrounded by outsized nanocrystals.

The application of scanning electron microscopy to fractography

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

Brooks, C.R.; McGill, B.L.

1994-10-01

Many failures involve fracture, and determination of the fracture process is a key factor in understanding the failure. This is frequently accomplished by characterizing the topography of the fracture surface. Scanning electron microscopy has a prominent role in fractography due to three features of the scanning electron microscope (SEM): high resolution, great depth of field, and the ability to obtain chemical information via analysis of the X-rays generated by the electrons. A qualitative treatment is presented of the interaction of electrons with a sample and the effect of the SEM operating parameters on image formation, quality, and X-ray analysis. Fractographsmore » are presented to illustrate these features of scanning electron microscopy and to illustrate the limitations and precautions in obtaining fractographs and x-ray analyses. The review is concluded with examples of fracture surface features of metallic, ceramic, and polymeric materials.« less

Retrieving spin textures on curved magnetic thin films with full-field soft X-ray microscopies

DOE PAGES

Streubel, Robert; Kronast, Florian; Fischer, Peter; ...

2015-07-03

X-ray tomography is a well-established technique to characterize 3D structures in material sciences and biology; its magnetic analogue—magnetic X-ray tomography—is yet to be developed. We demonstrate the visualization and reconstruction of magnetic domain structures in a 3D curved magnetic thin films with tubular shape by means of full-field soft X-ray microscopies. In the 3D arrangement of the magnetization is retrieved from a set of 2D projections by analysing the evolution of the magnetic contrast with varying projection angle. By using reconstruction algorithms to analyse the angular evolution of 2D projections provides quantitative information about domain patterns and magnetic coupling phenomenamore » between windings of azimuthally and radially magnetized tubular objects. In conclusion, the present approach represents a first milestone towards visualizing magnetization textures of 3D curved thin films with virtually arbitrary shape.« less

Component analyses of urinary nanocrystallites of uric acid stone formers by combination of high-resolution transmission electron microscopy, fast Fourier transformation, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy.

PubMed

Sun, Xin-Yuan; Xue, Jun-Fa; Xia, Zhi-Yue; Ouyang, Jian-Ming

2015-06-01

This study aimed to analyse the components of nanocrystallites in urines of patients with uric acid (UA) stones. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy (HRTEM), fast Fourier transformation (FFT) of HRTEM, and energy dispersive X-ray spectroscopy (EDS) were performed to analyse the components of these nanocrystallites. XRD and FFT showed that the main component of urinary nanocrystallites was UA, which contains a small amount of calcium oxalate monohydrate and phosphates. EDS showed the characteristic absorption peaks of C, O, Ca and P. The formation of UA stones was closely related to a large number of UA nanocrystallites in urine. A combination of HRTEM, FFT, EDS and XRD analyses could be performed accurately to analyse the components of urinary nanocrystallites.

Retrieving spin textures on curved magnetic thin films with full-field soft X-ray microscopies

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

Streubel, Robert; Kronast, Florian; Fischer, Peter

X-ray tomography is a well-established technique to characterize 3D structures in material sciences and biology; its magnetic analogue—magnetic X-ray tomography—is yet to be developed. We demonstrate the visualization and reconstruction of magnetic domain structures in a 3D curved magnetic thin films with tubular shape by means of full-field soft X-ray microscopies. In the 3D arrangement of the magnetization is retrieved from a set of 2D projections by analysing the evolution of the magnetic contrast with varying projection angle. By using reconstruction algorithms to analyse the angular evolution of 2D projections provides quantitative information about domain patterns and magnetic coupling phenomenamore » between windings of azimuthally and radially magnetized tubular objects. In conclusion, the present approach represents a first milestone towards visualizing magnetization textures of 3D curved thin films with virtually arbitrary shape.« less

Thermal analysis, X-ray powder diffraction and electron microscopy data related with the production of 1:1 Caffeine:Glutaric Acid cocrystals.

PubMed

Duarte, Íris; Andrade, Rita; Pinto, João F; Temtem, Márcio

2016-09-01

The data presented in this article are related to the production of 1:1 Caffeine:Glutaric Acid cocrystals as part of the research article entitled "Green production of cocrystals using a new solvent-free approach by spray congealing" (Duarte et al., 2016) [1]. More specifically, here we present the thermal analysis and the X-ray powder diffraction data for pure Glutaric Acid, used as a raw material in [1]. We also include the X-ray powder diffraction and electron microscopy data obtained for the 1:1 Caffeine:Glutaric Acid cocrystal (form II) produced using the cooling crystallization method reported in "Operating Regions in Cooling Cocrystallization of Caffeine and Glutaric Acid in Acetonitrile" (Yu et al., 2010) [2]. Lastly, we show the X-ray powder diffraction data obtained for assessing the purity of the 1:1 Caffeine:Glutaric cocrystals produced in [1].

An easy-to-implement filter for separating photo-excited signals from topography in scanning tunneling microscopy

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

Wang Kangkang; Rosenmann, Daniel; Holt, Martin

2013-06-15

In order to achieve elemental and chemical sensitivity in scanning tunneling microscopy (STM), synchrotron x-rays have been applied to excite core-level electrons during tunneling. The x-ray photo-excitations result in tip currents that are superimposed onto conventional tunneling currents. While carrying important physical information, the varying x-ray induced currents can destabilize the feedback loop causing it to be unable to maintain a constant tunneling current, sometimes even causing the tip to retract fully or crash. In this paper, we report on an easy-to-implement filter circuit that can separate the x-ray induced currents from conventional tunneling currents, thereby allowing simultaneous measurements ofmore » topography and chemical contrasts. The filter and the schematic presented here can also be applied to other variants of light-assisted STM such as laser STM.« less

A soft X-ray beamline for transmission X-ray microscopy at ALBA.

PubMed

Pereiro, E; Nicolás, J; Ferrer, S; Howells, M R

2009-07-01

The MISTRAL beamline is one of the seven phase-I beamlines at the ALBA synchrotron light source (Barcelona, Spain) that will be opened to users at the end of 2010. MISTRAL will be devoted to cryotomography in the water window and multi-keV spectral regions for biological applications. The optics design consists of a plane-grating monochromator that has been implemented using variable-line-spacing gratings to fulfil the requirements of X-ray microscopy using a reflective condenser. For instance, a fixed-focus condition independent of the included angle, constant magnification as well as coma and spherical aberration corrections are achieved with this system. The reported design is of wider use.

Three-dimensional imaging of nanoscale materials by using coherent x-rays

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

Miao, Jianwei

X-ray crystallography is currently the primary methodology used to determine the 3D structure of materials and macromolecules. However, many nanostructures, disordered materials, biomaterials, hybrid materials and biological specimens are noncrystalline and, hence, their structures are not accessible by X-ray crystallography. Probing these structures therefore requires the employment of different approaches. A very promising technique currently under rapid development is X-ray diffraction microscopy (or lensless imaging), in which the coherent X-ray diffraction pattern of a noncrystalline specimen is measured and then directly phased to obtain a high-resolution image. Through the DOE support over the past three years, we have applied X-raymore » diffraction microscopy to quantitative imaging of GaN quantum dot particles, and revealed the internal GaN-Ga2O3 core shell structure in three dimensions. By exploiting the abrupt change in the scattering cross-section near electronic resonances, we carried out the first experimental demonstration of resonant X-ray diffraction microscopy for element specific imaging. We performed nondestructive and quantitative imaging of buried Bi structures inside a Si crystal by directly phasing coherent X-ray diffraction patterns acquired below and above the Bi M5 edge. We have also applied X-ray diffraction microscopy to nondestructive imaging of mineral crystals inside biological composite materials - intramuscular fish bone - at the nanometer scale resolution. We identified mineral crystals in collagen fibrils at different stages of mineralization and proposed a dynamic mechanism to account for the nucleation and growth of mineral crystals in the collagen matrix. In addition, we have also discovered a novel 3D imaging modality, denoted ankylography, which allows for complete 3D structure determination without the necessity of sample titling or scanning. We showed that when the diffraction pattern of a finite object is sampled at a sufficiently fine scale on the Ewald sphere, the 3D structure of the object is determined by the 2D spherical pattern. We confirmed the theoretical analysis by performing 3D numerical reconstructions of a sodium silicate glass structure at 2 A resolution from a 2D spherical diffraction pattern alone. As X-ray free electron lasers are under rapid development worldwide, ankylography may open up a new horizon to obtain the 3D structure of a non-crystalline specimen from a single pulse and allow time-resolved 3D structure determination of disordered materials.« less

Composition measurement in substitutionally disordered materials by atomic resolution energy dispersive X-ray spectroscopy in scanning transmission electron microscopy.

PubMed

Chen, Z; Taplin, D J; Weyland, M; Allen, L J; Findlay, S D

2017-05-01

The increasing use of energy dispersive X-ray spectroscopy in atomic resolution scanning transmission electron microscopy invites the question of whether its success in precision composition determination at lower magnifications can be replicated in the atomic resolution regime. In this paper, we explore, through simulation, the prospects for composition measurement via the model system of Al x Ga 1-x As, discussing the approximations used in the modelling, the variability in the signal due to changes in configuration at constant composition, and the ability to distinguish between different compositions. Results are presented in such a way that the number of X-ray counts, and thus the expected variation due to counting statistics, can be gauged for a range of operating conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Laboratory-size three-dimensional x-ray microscope with Wolter type I mirror optics and an electron-impact water window x-ray source

NASA Astrophysics Data System (ADS)

Ohsuka, Shinji; Ohba, Akira; Onoda, Shinobu; Nakamoto, Katsuhiro; Nakano, Tomoyasu; Miyoshi, Motosuke; Soda, Keita; Hamakubo, Takao

2014-09-01

We constructed a laboratory-size three-dimensional water window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques, and observed bio-medical samples to evaluate its applicability to life science research fields. It consists of a condenser and an objective grazing incidence Wolter type I mirror, an electron-impact type oxygen Kα x-ray source, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit of around 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-μm scale three-dimensional fine structures were resolved.

Laboratory-size three-dimensional x-ray microscope with Wolter type I mirror optics and an electron-impact water window x-ray source.

PubMed

Ohsuka, Shinji; Ohba, Akira; Onoda, Shinobu; Nakamoto, Katsuhiro; Nakano, Tomoyasu; Miyoshi, Motosuke; Soda, Keita; Hamakubo, Takao

2014-09-01

We constructed a laboratory-size three-dimensional water window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques, and observed bio-medical samples to evaluate its applicability to life science research fields. It consists of a condenser and an objective grazing incidence Wolter type I mirror, an electron-impact type oxygen Kα x-ray source, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit of around 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-μm scale three-dimensional fine structures were resolved.

Simple route to (NH4)xWO3 nanorods for near infrared absorption

NASA Astrophysics Data System (ADS)

Guo, Chongshen; Yin, Shu; Dong, Qiang; Sato, Tsugio

2012-05-01

Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows.Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30612c

X-ray photoelectron spectroscopy and atomic force microscopy characterization of the effects of etching Zn xCd 1- xTe surfaces

NASA Astrophysics Data System (ADS)

George, M. A.; Azoulay, M.; Jayatirtha, H. N.; Burger, A.; Collins, W. E.; Silberman, E.

1993-10-01

X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) was used for the first time to characterize the chemical composition of modified surfaces of Zn xCd 1- xTe single crystals. These surface treatments were selected for their relevance to device preparation procedures. The XPS peaks indicated an increase of the tellurium and a depletion of the cadmium concentrations upon etching in bromine methanol solution. AFM revealed the formation of pronounced Te inclusions. Higher x values correlated with a decrease in residual bromine left on the surface, while cut and polished samples had higher oxide concentrations and increased bromination of the surface than cleaved samples.

The Feeding Habits of Mesosauridae

NASA Astrophysics Data System (ADS)

Silva, Rivaldo R.; Ferigolo, Jorge; Bajdek, Piotr; Piñeiro, Graciela

2017-03-01

Mesosauridae comprises the oldest known aquatic amniotes which lived in Gondwana during the Early Permian. Previous work in the Uruguayan mesosaur-bearing Mangrullo Formation suggested that mesosaurids lived in an inland water body, inferred as moderately hypersaline, with exceptional preservational conditions that justified describing these strata as a Fossil-Lagerstätte. Exquisitely preserved articulated mesosaur skeletons, including gastric content and associated coprolites, from the Brazilian Iratí Formation in the State of Goiás (central-western Brazil) indicate excellent conditions of preservation, extending the Konservat-Lagerstätte designation to both units in the Paraná Basin. The near-absence of more resistant fossil remains, like actinopterygian and temnospondyl bones, demonstrates the faunistic poverty of the mesosaur-bearing “salty sea”. Our studies of the alimentary habits of mesosaurids through the use of stereoscopic microscopy, light and electronic microscopy, and X-ray diffractometry suggest that the diet of mesosaurids was predominantly composed of pygocephalomorph crustaceans (possibly not exceeding 20 mm in length). However, the presence of bones and bone fragments of small mesosaurs in the gastric content, cololites, coprolites, and possible regurgitalites may also indicate cannibalistic and/or scavenging habits. Cannibalism is relatively common among vertebrates, particularly during conditions of environmental stress, like food shortage. Likewise, the apparent abundance of pygocephalomorph crustacean fossils in the Iratí and Mangrullo Formations, outside and within the studied gastric, cololite, and coprolite contents, might have to do with environmental stress possibly caused by volcanic activity, in particular ash spread into the basin during the Early Permian. In this context, casual necrophagy on the dead bodies of small mesosaurs and large pygocephalomorphs might have been an alternative alimentary behavior adopted for survival in mesosaurs.

Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine.

PubMed

Hu, Liang; Sun, Hongrui; Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying; Wang, Siling

2015-02-01

We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers. Copyright © 2014 Elsevier B.V. All rights reserved.

Physical and structural changes induced by high pressure on corn starch, rice flour and waxy rice flour.

PubMed

Cappa, Carola; Lucisano, Mara; Barbosa-Cánovas, Gustavo V; Mariotti, Manuela

2016-07-01

The impact of high pressure (HP) processing on corn starch, rice flour and waxy rice flour was investigated as a function of pressure level (400MPa; 600MPa), pressure holding time (5min; 10min), and temperature (20°C; 40°C). Samples were pre-conditioned (final moisture level: 40g/100g) before HP treatments. Both the HP treated and the untreated raw materials were evaluated for pasting properties and solvent retention capacity, and investigated by differential scanning calorimetry, X-ray diffractometry and environmental scanning electron microscopy. Different pasting behaviors and solvent retention capacities were evidenced according to the applied pressure. Corn starch presented a slower gelatinization trend when treated at 600MPa. Corn starch and rice flour treated at 600MPa showed a higher retention capacity of carbonate and lactic acid solvents, respectively. Differential scanning calorimetry and environmental scanning electron microscopy investigations highlighted that HP affected the starch structure of rice flour and corn starch. Few variations were evidenced in waxy rice flour. These results can assist in advancing the HP processing knowledge, as the possibility to successfully process raw samples in a very high sample-to-water concentration level was evidenced. This work investigates the effect of high pressure as a potential technique to modify the processing characteristics of starchy materials without using high temperature. In this case the starches were processed in the powder form - and not as a slurry as in previously reported studies - showing the flexibility of the HP treatment. The relevance for industrial application is the possibility to change the structure of flour starches, and thus modifying the processability of the mentioned products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Surface microstructure and high temperature corrosion resistance of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam

NASA Astrophysics Data System (ADS)

Hao, Shengzhi; Zhao, Limin; He, Dongyun

2013-10-01

The surface microstructure of arc-sprayed FeCrAl coating irradiated by high current pulsed electron beam (HCPEB) with long pulse duration of 200 μs was characterized by using optical microscopy, scanning electron microscopy and X-ray diffractometry. The distribution of chemical composition in modified surface layer was measured with electron probe micro-analyzer. The high temperature corrosion resistance of FeCrAl coating was tested in a saturated Na2SO4 and K2SO4 solution at 650 °C. After HCPEB irradiation, the coarse surface of arc-sprayed coating was changed as discrete bulged nodules with smooth and compact appearance. When using low energy density of 20 J/cm2, the surface modified layer was continuous entirely with an average melting depth of ˜30 μm. In the surface remelted layer, Fe and Cr elements gave a uniform distribution, while Al and O elements agglomerated particularly at the concave part between nodule structures to form α-Al2O3 phase. After high temperature corrosion tests, the FeCrAl coating treated with HCPEB of 20 J/cm2 remained a glossy surface with weight increment of ˜51 mg/cm2, decreased by 20% as compared to the initial sample. With the increasing energy density of HCPEB irradiation, the integrity of surface modified layer got segmented due to the formation of larger bulged nodules and cracks at the concave parts. For the HCPEB irradiation of 40 J/cm2, the high temperature corrosion resistance of FeCrAl coating was deteriorated drastically.

Effects of Nano-CeO₂ with Different Nanocrystal Morphologies on Cytotoxicity in HepG2 Cells.

PubMed

Wang, Lili; Ai, Wenchao; Zhai, Yanwu; Li, Haishan; Zhou, Kebin; Chen, Huiming

2015-09-02

Cerium oxide nanoparticles (nano-CeO₂) have been reported to cause damage and apoptosis in human primary hepatocytes. Here, we compared the toxicity of three types of nano-CeO₂ with different nanocrystal morphologies (cube-, octahedron-, and rod-like crystals) in human hepatocellular carcinoma cells (HepG2). The cells were treated with the nano-CeO₂ at various concentrations (6.25, 12.5, 25, 50, 100 μg/mL). The crystal structure, size and morphology of nano-CeO₂ were investigated by X-ray diffractometry and transmission electron microscopy. The specific surface area was detected using the Brunauer, Emmet and Teller method. The cellular morphological and internal structure were observed by microscopy; apoptotic alterations were measured using flow cytometry; nuclear DNA, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and glutathione (GSH) in HepG2 cells were measured using high content screening technology. The scavenging ability of hydroxyl free radicals and the redox properties of the nano-CeO₂ were measured by square-wave voltammetry and temperature-programmed-reduction methods. All three types of nano-CeO₂ entered the HepG2 cells, localized in the lysosome and cytoplasm, altered cellular shape, and caused cytotoxicity. The nano-CeO₂ with smaller specific surface areas induced more apoptosis, caused an increase in MMP, ROS and GSH, and lowered the cell's ability to scavenge hydroxyl free radicals and antioxidants. In this work, our data demonstrated that compared with cube-like and octahedron-like nano-CeO₂, the rod-like nano-CeO₂ has lowest toxicity to HepG2 cells owing to its larger specific surface areas.

Use of nanoindentation technique for a better understanding of the fracture toughness of Strombus gigas conch shell

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

Romana, L., E-mail: laurence.romana@univ-ag.fr; Thomas, P.; Bilas, P.

2013-02-15

In this work the nanochemical properties of the composite organomineral biomaterial constituting Strombus gigas conch shell are studied by means of dynamic mechanical analyses associated to nanoidentation technique. The measurements are performed on shell samples presenting different surface orientations relative to the growth axis of the conch shell. The influence of the organic component of the biomaterial on its nanomechanical properties is also investigated by studying fresh and dried S. gigas conch shells. Monocrystalline aragonite is used as a reference. For the understanding of nanochemical behaviour, special attention is paid to the pop in events observed on the load/displacement curvesmore » which results from nanofractures' initiation and propagation occuring during the load process. In order to better understand the mechanical properties systematic studies of the structure and morphology are performed using scanning electron microscopy, atomic force microscopy and X-ray diffractometry. The hardness and Young's modulus values measured on bio aragonite samples are close to those of the aragonite mineral standard. This surprising result shows that, H and E values are not related to the bio composition and lamellar structure of the bio aragonite. However, it was found that the organic layer and the micro architecture strongly influence the nanofracture initiation and propagation processes in the samples. Statistic study of the pop-in events can help to predict the macroscopic mechanical behaviour of the material. - Highlights: ► Nanomechanical properties of Strombus gigas conch shell ► Low influence of the crossed lamellar structure on H and E values at the nano scale ► Strong influence of the crossed lamellar on nanocracks initiation ► Correlation between mechanical behaviors at the macro and nano scales.« less

Effects of solution pH and electrical parameters on hydroxyapatite coatings deposited by a plasma-assisted electrophoresis technique.

PubMed

Nie, X; Leyland, A; Matthews, A; Jiang, J C; Meletis, E I

2001-12-15

Hydroxyapatite (HA) coatings can be deposited using a hybrid process of plasma electrolysis and electrophoresis, called plasma-assisted electrophoretic deposition (PEPD). HA aqueous suspensions with various pH values were prepared using a modified ultrasonic cleaning bath as an agitator/stirrer. Both DC and unbalanced AC power supplies were used to bias the titanium alloy substrate materials employed in this work. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to observe and analyze coating morphology and microstructure. It was shown that the morphology and composition of the calcium phosphate coatings were significantly influenced by solution pH values; the level of "pure" HA in the coatings' composition corresponded to both solution pH and the type of power supply employed. Loss of hydroxyl radials (i.e., dehydroxylation), which degrades the performance of the hydroxyapatite coating in terms of long-term chemical and mechanical stability, can be virtually eliminated by a combination of high pH and unbalanced AC plasma power. In addition, the underlying TiO2 coatings used to support the HA layer (preproduced by plasma electrolysis process) have a nanoscaled (10-20 nm) polycrystalline structure. TEM studies also revealed a dense, continuous amorphous titania layer (10 nm in thickness) at the interface between the Ti alloy substrate and the TiO2 layer, which may play a role in improving the corrosion resistance of the substrate. Such a nanophase TiO2 layer (if used as a coating alone) may also provide a further improvement in osteoinductive properties, compared to a conventional TiO2 coating on the Ti alloy substrate. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 612-618, 2001

A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel.

PubMed

Rakhshaei, Rasul; Namazi, Hassan

2017-04-01

Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV-vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles solved this problem and the CMC/ZnO-MCM-41 showed a great improvement in tensile strength (12%), swelling (100%), erosion (53%) and gas permeability (500%) properties. Drug delivery and antibacterial properties of the nanocomposite hydrogel films studied using tetracycline (TC) as a broad spectrum antibiotic and showed a sustained TC release. This could efficiently decrease bandage exchange. Cytocompatibility of the nanocomposite hydrogel films has been analyzed in adipose tissue-derived stem cells (ADSCs) and results showed cytocompatibility of CMC/ZnO-MCM-41. Based on these results the prepared CMC nanocomposite hydrogel containing ZnO impregnated MCM-41, could serve as a kind of promising wound dressing with sustained drug delivery properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Structural characterization of silver nanoparticles phyto-mediated by a plant waste, seed hull of Vigna mungo and their biological applications

NASA Astrophysics Data System (ADS)

Varadavenkatesan, Thivaharan; Vinayagam, Ramesh; Selvaraj, Raja

2017-11-01

Nanobiotechnology has rapidly become a critical facet of nanotechnology. The green synthesis of silver nanoparticles, making use of the hull of black gram (Vigna mungo), paves the way for a simple and eco-friendly utilization of a domestic waste to a product with antioxidant and anticoagulant activities. The emergence of silver nanoparticles was characterized by a variety of methods UV-visible spectrophotometry, scanning electron microscopy added to energy dispersive spectroscopy, X-ray diffractometry, particle size distribution and FT-IR spectroscopy analyses. A discrete band at 421 nm was obtained from UV-visible spectroscopy of the silver nanoparticle suspension. The extract sourced from the hull of black gram showed evidence of the presence of a variety of functional moieties of phytochemicals using FTIR spectroscopy. These were also deemed responsible for maintaining the stability of silver nanoparticles. SEM and EDAX techniques combined, proved that the zero-valent silver nanoparticles were lesser than 100 nm in size. The crystallinity of the nanoparticles was confirmed, as deduced by the (1 1 1) plane, from XRD analysis. The potential of the phytochemicals in maintaining the steadiness of nanoparticles was implied by the zeta potential value that stood at -30.3 mV. In the current study, we have endeavored to comprehend the antioxidant and anticoagulant nature of the green-synthesized benign silver nanoparticles.

In vitro/in vivo evaluation of an optimized fast dissolving oral film containing olanzapine co-amorphous dispersion with selected carboxylic acids.

PubMed

Maher, Eman Magdy; Ali, Ahmed Mahmoud Abdelhaleem; Salem, Heba Farouk; Abdelrahman, Ahmed Abdelbary

2016-10-01

Improvement of water solubility, dissolution rate, oral bioavailability, and reduction of first pass metabolism of OL (OL), were the aims of this research. Co-amorphization of OL carboxylic acid dispersions at various molar ratios was carried out using rapid solvent evaporation. Characterization of the dispersions was performed using differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FTIR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Dispersions with highest equilibrium solubility were formulated as fast dissolving oral films. Modeling and optimization of film formation were undertaken using artificial neural networks (ANNs). The results indicated co-amorphization of OL-ascorbic acid through H-bonding. The co-amorphous dispersions at 1:2 molar ratio showed more than 600-fold increase in solubility of OL. The model optimized fast dissolving film prepared from the dispersion was physically and chemically stable, demonstrated short disintegration time (8.5 s), fast dissolution (97% in 10 min) and optimum tensile strength (4.9 N/cm 2 ). The results of in vivo data indicated high bioavailability (144 ng h/mL) and maximum plasma concentration (14.2 ng/mL) compared with the marketed references. Therefore, the optimized co-amorphous OL-ascorbic acid fast dissolving film could be a valuable solution for enhancing the physicochemical and pharmacokinetic properties of OL.

Material Analysis of Coated Siliconized Silicon Carbide (SiSiC) Honeycomb Structures for Thermochemical Hydrogen Production

PubMed Central

Neises-von Puttkamer, Martina; Simon, Heike; Schmücker, Martin; Roeb, Martin; Sattler, Christian; Pitz-Paal, Robert

2013-01-01

In the present work, thermochemical water splitting with siliconized silicon carbide (SiSiC) honeycombs coated with a zinc ferrite redox material was investigated. The small scale coated monoliths were tested in a laboratory test-rig and characterized by X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) with corresponding micro analysis after testing in order to characterize the changes in morphology and composition. Comparison of several treated monoliths revealed the formation of various reaction products such as SiO2, zircon (ZrSiO4), iron silicide (FeSi) and hercynite (FeAl2O4) indicating the occurrence of various side reactions between the different phases of the coating as well as between the coating and the SiSiC substrate. The investigations showed that the ferrite is mainly reduced through reaction with silicon (Si), which is present in the SiSiC matrix, and silicon carbide (SiC). These results led to the formulation of a new redox mechanism for this system in which Zn-ferrite is reduced through Si forming silicon dioxide (SiO2) and through SiC forming SiO2 and carbon monoxide. A decline of hydrogen production within the first 20 cycles is suggested to be due to the growth of a silicon dioxide and zircon layer which acts as a diffusion barrier for the reacting specie. PMID:28809316

Material Analysis of Coated Siliconized Silicon Carbide (SiSiC) Honeycomb Structures for Thermochemical Hydrogen Production.

PubMed

Neises-von Puttkamer, Martina; Simon, Heike; Schmücker, Martin; Roeb, Martin; Sattler, Christian; Pitz-Paal, Robert

2013-01-31

In the present work, thermochemical water splitting with siliconized silicon carbide (SiSiC) honeycombs coated with a zinc ferrite redox material was investigated. The small scale coated monoliths were tested in a laboratory test-rig and characterized by X-ray diffractometry (XRD) and Scanning Electron Microscopy (SEM) with corresponding micro analysis after testing in order to characterize the changes in morphology and composition. Comparison of several treated monoliths revealed the formation of various reaction products such as SiO₂, zircon (ZrSiO₄), iron silicide (FeSi) and hercynite (FeAl₂O₄) indicating the occurrence of various side reactions between the different phases of the coating as well as between the coating and the SiSiC substrate. The investigations showed that the ferrite is mainly reduced through reaction with silicon (Si), which is present in the SiSiC matrix, and silicon carbide (SiC). These results led to the formulation of a new redox mechanism for this system in which Zn-ferrite is reduced through Si forming silicon dioxide (SiO₂) and through SiC forming SiO₂ and carbon monoxide. A decline of hydrogen production within the first 20 cycles is suggested to be due to the growth of a silicon dioxide and zircon layer which acts as a diffusion barrier for the reacting specie.

Pretreatment of eucalyptus wood chips for enzymatic saccharification using combined sulfuric acid-free ethanol cooking and ball milling.

PubMed

Teramoto, Yoshikuni; Tanaka, Noriko; Lee, Seung-Hwan; Endo, Takashi

2008-01-01

A combined sulfuric acid-free ethanol cooking and pulverization process was developed in order to achieve the complete saccharification of the cellulosic component of woody biomass, thereby avoiding the problems associated with the use of strong acid catalysts. Eucalyptus wood chips were used as a raw material and exposed to an ethanol/water/acetic acid mixed solvent in an autoclave. This process can cause the fibrillation of wood chips. During the process, the production of furfural due to an excessive degradation of polysaccharide components was extremely low and delignification was insignificant. Therefore, the cooking process is regarded not as a delignification but as an activation of the original wood. Subsequently, the activated solid products were pulverized by ball-milling in order to improve their enzymatic digestibility. Enzymatic hydrolysis experiments demonstrated that the conversion of the cellulosic components into glucose attained 100% under optimal conditions. Wide-angle X-ray diffractometry and particle size distribution analysis revealed that the scale affecting the improvement of enzymatic digestibility ranged from 10 nm to 1 microm. Field emission scanning electron microscopy depicted that the sulfuric acid-free ethanol cooking induced a pore formation by the removal of part of the lignin and hemicellulose fractions in the size range from a few of tens nanometers to several hundred nanometers. (c) 2007 Wiley Periodicals, Inc.

Xylitol as a potential co-crystal co-former for enhancing dissolution rate of felodipine: preparation and evaluation of sublingual tablets.

PubMed

Arafa, Mona F; El-Gizawy, Sanaa A; Osman, Mohamed A; El Maghraby, Gamal M

2018-06-01

Dissolution enhancement is a promising strategy for improving drug bioavailability. Co-crystallization of drugs with inert material can help in this direction. The benefit will become even greater if the inert material can form co-crystal while maintaining its main function as excipient. Accordingly, the objective of the current study was to investigate xylitol as a potential co-crystal co-former for felodipine with the goal of preparing felodipine sublingual tablets. Co-crystallization was achieved by wet co-grinding of the crystals deposited from methanolic solutions containing felodipine with increasing molar ratios of xylitol (1:1, 1:2 and 1:3). The developed co-crystals were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) before monitoring drug dissolution. These results reflected the development of new crystalline species depending on the relative proportions of felodipine and xylitol with complete co-crystallization of felodipine being achieved in the presence of double its molar concentration of xylitol. This co-crystal formulation was compressed into sublingual tablet with ultrashort disintegration time with subsequent fast dissolution. Co-crystal formation was associated with enhanced dissolution with the optimum formulation producing the fastest dissolution rate. In conclusion, xylitol can be considered as a co-crystal co-former for enhanced dissolution rate of drugs.

Development of highly porous scaffolds based on bioactive silicates for dental tissue engineering

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

Goudouri, O.M., E-mail: menti.goudouri@ww.uni-erlangen.de; Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki; Theodosoglou, E.

Graphical abstract: - Highlights: • Synthesis of an Mg-based glass-ceramic via the sol–gel technique. • The heat treatment of the glass-ceramic promoted the crystallization of akermanite. • Akermanite scaffolds coated with gelatin were successfully fabricated. • An HCAp layer was developed on the surface of all scaffolds after 9 days in SBF. - Abstract: Various scaffolding materials, ceramics and especially Mg-based ceramic materials, including akermanite (Ca{sub 2}MgSi{sub 2}O{sub 7}) and diopside (CaMgSi{sub 2}O{sub 6}), have attracted interest for dental tissue regeneration because of their improved mechanical properties and controllable biodegradation. The aim of the present work was the synthesis ofmore » an Mg-based glass-ceramic, which would be used for the construction of workable akermanite scaffolds. The characterization of the synthesized material was performed by Fourier Transform Infrared Spectroscopy (FTIR) X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). Finally, the apatite forming ability of the scaffolds was assessed by immersion in simulated body fluid. The scaffolds were fabricated by the foam replica technique and were subsequently coated with gelatin to provide a functional surface for increased cell attachment. Finally, SEM microphotographs and FTIR spectra of the scaffolds after immersion in SBF solution indicated the inorganic bioactive character of the scaffolds suitable for the intended applications in dental tissue engineering.« less

Differentiations of Chitin Content and Surface Morphologies of Chitins Extracted from Male and Female Grasshopper Species

PubMed Central

Kaya, Murat; Lelešius, Evaldas; Nagrockaitė, Radvilė; Sargin, Idris; Arslan, Gulsin; Mol, Abbas; Baran, Talat; Can, Esra; Bitim, Betul

2015-01-01

In this study, we used Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), and scanning electron microscopy (SEM) to investigate chitin structure isolated from both sexes of four grasshopper species. FT-IR, EA, XRD, and TGA showed that the chitin was in the alpha form. With respect to gender, two main differences were observed. First, we observed that the quantity of chitin was greater in males than in females and the dry weight of chitin between species ranged from 4.71% to 11.84%. Second, using SEM, we observed that the male chitin surface structure contained 25 – 90nm wide nanofibers and 90 – 250 nm nanopores, while no pores or nanofibers were observed in the chitin surface structure of the majority of females (nanofibers were observed only in M. desertus females). In contrast, the elemental analysis, thermal properties, and crystalline index values for chitin were similar in males and females. Also, we carried out enzymatic digestion of the isolated chitins using commercial chitinase from Streptomyces griseus. We observed that there were no big differences in digestion rate of the chitins from both sexes and commercial chitin. The digestion rates were for grasshoppers’ chitins; 88.45–95.48% and for commercial chitin; 94.95%. PMID:25635814

Cu-Doped ZnO Thin Films Deposited by a Sol-Gel Process Using Two Copper Precursors: Gas-Sensing Performance in a Propane Atmosphere

PubMed Central

Gómez-Pozos, Heberto; Arredondo, Emma Julia Luna; Maldonado Álvarez, Arturo; Biswal, Rajesh; Kudriavtsev, Yuriy; Pérez, Jaime Vega; Casallas-Moreno, Yenny Lucero; Olvera Amador, María de la Luz

2016-01-01

A study on the propane gas-sensing properties of Cu-doped ZnO thin films is presented in this work. The films were deposited on glass substrates by sol-gel and dip coating methods, using zinc acetate as a zinc precursor, copper acetate and copper chloride as precursors for doping. For higher sensitivity values, two film thickness values are controlled by the six and eight dippings, whereas for doping, three dippings were used, irrespective of the Cu precursor. The film structure was analyzed by X-ray diffractometry, and the analysis of the surface morphology and film composition was made through scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS), respectively. The sensing properties of Cu-doped ZnO thin films were then characterized in a propane atmosphere, C3H8, at different concentration levels and different operation temperatures of 100, 200 and 300 °C. Cu-doped ZnO films doped with copper chloride presented the highest sensitivity of approximately 6 × 104, confirming a strong dependence on the dopant precursor type. The results obtained in this work show that the use of Cu as a dopant in ZnO films processed by sol-gel produces excellent catalysts for sensing C3H8 gas. PMID:28787885

Magnetron sputtering fabrication and photoelectric properties of WSe2 film solar cell device

NASA Astrophysics Data System (ADS)

Mao, Xu; Zou, Jianpeng; Li, Hongchao; Song, Zhengqi; He, Siru

2018-06-01

Tungsten diselenide (WSe2) films with different growing orientations exhibit diverse photoelectric properties. The WSe2 film with C-axis⊥substrate texture has been prepared and applied to thin-film solar cells. W nanofilms with a thickness of 270 nm were deposited onto the Mo bottom electrode and then heat-treated in selenium vapor to synthesize WSe2 films with a thickness of 1 μm. ZnO films were deposited onto WSe2 films to form a P-N junction and ITO films were deposited subsequently as the conductive layer. X-ray diffractometry, scanning electron microscopy and UV-vis-NIR spectro-analysis instrument were employed to analyze the phase composition, optical absorptivity and micromorphology of WSe2 films and the WSe2 solar cell device. WSe2 films exhibit excellent photoelectric performance with an optical absorption coefficient greater than 105 cm-1 across the visible spectrum. The calculated direct and indirect band gap of the WSe2 films is 1.48 eV and 1.25 eV, respectively. With the application of standard glass/Mo/WSe2/ZnO/ITO/Ag device structure, the open-circuit voltage of the battery device is 82 mV. The short-circuit current density is 2.98 mA/cm2 and the filling factor is 0.32. The photoelectric conversion efficiency of the WSe2 film solar cell device is 0.79%.

Effect of spark plasma sintering on the microstructure and in vitro behavior of plasma sprayed HA coatings.

PubMed

Yu, L-G; Khor, K A; Li, H; Cheang, P

2003-07-01

The crystalline phases and degree of crystallinity in plasma sprayed calcium phosphate coatings on Ti substrates are crucial factors that influence the biological interactions of the materials in vivo. In this study, plasma sprayed hydroxyapatite (HA) coatings underwent post-spray treatment by the spark plasma sintering (SPS) technique at 500 degrees C, 600 degrees C, and 700 degrees C for duration of 5 and 30 min. The activity of the HA coatings before and after SPS are evaluated in vitro in a simulated body fluid. The surface microstructure, crystallinity, and phase composition of each coating is characterized by scanning electron microscopy and X-ray diffractometry before, and after in vitro incubation. Results show that the plasma sprayed coatings treated for 5 min in SPS demonstrated increased proportion of beta-TCP phase with a preferred-orientation in the (214) plane, and the content of beta-TCP phase corresponded to SPS temperature, up to 700 degrees C. SPS treatment at 700 degrees C for 30 min enhanced the HA content in the plasma spray coating as well. The HA coatings treated in SPS for 5 min revealed rapid surface morphological changes during in vitro incubation (up to 12 days), indicating that the surface activity is enhanced by the SPS treatment. The thickest apatite layer was found in the coating treated by SPS at 700 degrees C for 5 min.

Starch-based xerogels: Effect of acetylation on Physicochemical and rheological properties.

PubMed

Kemas, Chinwe U; Ngwuluka, Ndidi C; Ochekpe, Nelson A; Nep, Elijah I

2017-05-01

This study was aimed at evaluating the physicochemical and rheological properties of starch-based xerogels. The starch from the shoots of Borassus aethiopium was physically modified by xerogelization, and chemically by acetylation, and combination of acetylation and xerogelization. The solubility, swelling and syneresis of the starches were determined by gravimetric techniques. Evaluation of the native starch and derivatives was done using microscopy, Fourier transform infra-red (FTIR), x-ray diffractometry (XRD), and 1 H NMR spectroscopy. Rheological evaluation was done on 10%w/v dispersions using a Bohlin Gemini rheometer (fitted with a 55mm and 2° cone and plate geometry with gap of 70). The diffractograms displayed three peaks, centered on 2θ=15.3, 17.2 and 23.1° for the native and the starch acetate while the xerogel and the starch acetate xerogel were amorphous. The 1 H NMR and FTIR confirmed the presence of acetyl groups at about 2.05ppm and 1720cm -1 , respectively. Acetylation of the native starch resulted in improvement of solubility. The starch acetate-xerogel sample formed viscoelastic gels without the need for heating. Acetylation and/or xerogelization of the native starch inhibited syneresis. Starch acetate-xerogels, may find application as stabilizer or suspending agent in liquid food and pharmaceutical formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of osteoinduction using a porous hydroxyapatite coating prepared by micro-arc oxidation on a new titanium alloy.

PubMed

Jing, Wensen; Zhang, Minghua; Jin, Lei; Zhao, Jian; Gao, Qing; Ren, Min; Fan, Qingyu

2015-12-01

Surface modification and material improvement is now an important way to improve the osseointegration between bone and uncemented prothesis. The purpose of this study was to investigate the bone ingrowth potential of porous hydroxyapatite (HA) coatings prepared by micro-arc oxidation (MAO) on Ti-3Zr-2Sn-3Mo-25Nb, a new titanium alloy. HA-coated specimens were implanted in the left proximal femoral medullary canal of beagles for 4, 12, and 24 weeks, and uncoated specimens were implanted in the right as a control. The surface morphology and phase composition were investigated with environmental scanning electron microscopy and X-ray diffractometry. The bone ingrowth was assessed by histomorphometry. A pull-out test was performed to assess the mechanical performance of the bone-implant interface. A porous coating was well prepared on the new titanium alloy by using the MAO method. The bone-to-implant contact was significantly higher for the HA-coated group compared to that in the uncoated group. Mechanical tests showed that the HA-coated group had significantly higher maximum force at the bone-implant interface compared to the uncoated specimens. MAO is a suitable coating approach for this new titanium alloy. The HA coating prepared by this approach can significantly promote bone ingrowth and the mechanical performance of the bone-implant interface. Copyright © 2015. Published by Elsevier Ltd.

The negative electrode development for a Ni-MH battery prototype

NASA Astrophysics Data System (ADS)

Cuscueta, D. J.; Ghilarducci, A. A.; Salva, H. R.; Milocco, R. H.; Castro, E. B.

2009-10-01

The negative electrode development for a nickel-metal hydride battery (Ni-MH) prototype was performed with the following procedure: (1) the Lm 0.95Ni 3.8Co 0.3Mn 0.3Al 0.4 (Lm=lanthanum rich mischmetal) intermetallic alloy was elaborated by melting the pure elements in an induction furnace inside a boron nitride crucible under an inert atmosphere, (2) the obtained alloy was crushed and sieved between 44 and 74 μm and mixed with teflonized carbon; (3) the compound was assembled together with a current collector and pressed in a cylindrical matrix. The obtained electrode presented a disc shape, with 11 mm diameter and approximately 1 mm thickness. The crystalline structure of the hydrogen storage alloy was examined using X-ray diffractometry. The measured hcp lattice volume was 1.78% larger than the precursor LaNi 5 intermetallic alloy, increasing the available space for hydrogen movement. Energy dispersive spectroscopy (EDS) and scanning electronic microscopy (SEM) measurements were used before and after hydriding in order to verify the alloy sample homogeneity. The negative electrode was electrochemically tested by using a laboratory cell. It activates almost totally in its first cycle, which is an excellent characteristic from the commercial point of view. The maximum discharge capacity reached was 314.2 mA h/g in the 10th cycle.

Synthesis and characterization of carboxymethyl potato starch and its application in reactive dye printing.

PubMed

Zhang, Bing; Gong, Honghong; Lü, Shaoyu; Ni, Boli; Liu, Mingzhu; Gao, Chunmei; Huang, Yinjuan; Han, Fei

2012-11-01

Carboxymethyl potato starch (CMPS) was synthesized with a simple dry and multi-step method as a product of the reaction of native potato starch and monochloroacetic acid in the presence of sodium hydroxide. The influence of the molar ratio of sodium hydroxide to anhydroglucose unit, the volume of 95% (v/v) ethanol, the rotation rate of motor driven stirrer and the reaction time for degree of substitution (DS) were evaluated. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). FTIR spectrometry showed new bonds at 1618 and 1424 cm⁻¹ when native starch underwent carboxymethylation. SEM pictures showed that the smooth surface of native starch particles was mostly ruptured. XRD revealed that starch crystallinity was reduced after carboxymethylation. The viscosity of the mixture paste of carboxymethyl starch and sodium alginate (SA) was measured using a rotational viscometer. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with SA. And the results indicated that the mixed paste could partially replace SA as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermal transport through Ge-rich Ge/Si superlattices grown on Ge(0 0 1)

NASA Astrophysics Data System (ADS)

Thumfart, L.; Carrete, J.; Vermeersch, B.; Ye, N.; Truglas, T.; Feser, J.; Groiss, H.; Mingo, N.; Rastelli, A.

2018-01-01

The cross-plane thermal conductivities of Ge-rich Si/Ge superlattices have been measured using both time-domain thermoreflectance and the differential 3ω method. The superlattices were grown by molecular beam epitaxy on Ge(0 0 1) substrates. Crystal quality and structural information were investigated by x-ray diffractometry and transmission electron microscopy. The influence of segregation during growth on the composition profiles was modeled using the experimental growth temperatures and deposition rates. Those profiles were then employed to obtain parameter-free theoretical estimates of the thermal conductivity by combining first-principles calculations, Boltzmann transport theory and phonon Green’s functions. Good agreement between theory and experiment is observed. The thermal conductivity shows a strong dependence on the composition and the thickness of the samples. Moreover, the importance of the composition profile is reflected in the fact that the thermal conductivity of the superlattices is considerably lower than predicted values for alloys with the same average composition and thickness. Measurement on different samples with the same Si layer thickness and number of periods, but different Ge layer thickness, show that the thermal resistance is only weakly dependent on the Ge layers. We analyze this phenomenon based on the first-principles mode, and build an approximate parametrization showing that, in this regime, the resistivity of a SL is roughly linear on the amount of Si.

Spray-Freeze Drying: a Suitable Method for Aerosol Delivery of Antibodies in the Presence of Trehalose and Cyclodextrins.

PubMed

Pouya, Maryam Amini; Daneshmand, Behnaz; Aghababaie, Shabnam; Faghihi, Homa; Vatanara, Alireza

2018-05-08

We aimed to prepare spray-freeze-dried powder of IgG considering physicochemical stability and aerodynamic aspects. Spray-freeze drying (SFD) exposes proteins to various stresses which should be compensated by suitable stabilizers. The competence of cyclodextrins (CDs), namely beta-cyclodextrin (βCD) and hydroxypropyl βCD (HPβCD), at very low concentrations, was investigated in the presence of separate mannitol- and trehalose-based formulations. Spray-freeze-dried preparations were quantified in terms of monomer recovery and conformation by size exclusion chromatography (SEC-HPLC) and Fourier transform infrared (FTIR) spectroscopy, respectively. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) were employed to identify the thermal characteristics of powders. Particle morphology was visualized by scanning electron microscopy (SEM). Aerodynamic behavior of powders was checked through an Anderson cascade impactor (ACI). Although all formulations protected antibody from aggregation during the SFD process (aggregation < 1%), mannitol-containing ones failed upon the storage (19.54% in the worst case). Trehalose-HPβCD incomparably preserved the formulation with fine particle fraction (FPF) of 51.29%. Crystallization of mannitol resulted in IgG destabilization upon storage. Although employed concentration of CDs is too low (less than 50:1 molar ratio to protein), they successfully served as stabilizing agents in SFD with perfect improvement in aerosol functionality. Graphical Abstract ᅟ.