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

Structural interpretation in composite systems using powder X-ray diffraction: applications of error propagation to the pair distribution function.

PubMed

Moore, Michael D; Shi, Zhenqi; Wildfong, Peter L D

2010-12-01

To develop a method for drawing statistical inferences from differences between multiple experimental pair distribution function (PDF) transforms of powder X-ray diffraction (PXRD) data. The appropriate treatment of initial PXRD error estimates using traditional error propagation algorithms was tested using Monte Carlo simulations on amorphous ketoconazole. An amorphous felodipine:polyvinyl pyrrolidone:vinyl acetate (PVPva) physical mixture was prepared to define an error threshold. Co-solidified products of felodipine:PVPva and terfenadine:PVPva were prepared using a melt-quench method and subsequently analyzed using PXRD and PDF. Differential scanning calorimetry (DSC) was used as an additional characterization method. The appropriate manipulation of initial PXRD error estimates through the PDF transform were confirmed using the Monte Carlo simulations for amorphous ketoconazole. The felodipine:PVPva physical mixture PDF analysis determined ±3σ to be an appropriate error threshold. Using the PDF and error propagation principles, the felodipine:PVPva co-solidified product was determined to be completely miscible, and the terfenadine:PVPva co-solidified product, although having appearances of an amorphous molecular solid dispersion by DSC, was determined to be phase-separated. Statistically based inferences were successfully drawn from PDF transforms of PXRD patterns obtained from composite systems. The principles applied herein may be universally adapted to many different systems and provide a fundamentally sound basis for drawing structural conclusions from PDF studies.

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.

Utilization of oriented crystal growth for screening of aromatic carboxylic acids cocrystallization with urea

NASA Astrophysics Data System (ADS)

Przybyłek, Maciej; Ziółkowska, Dorota; Kobierski, Mirosław; Mroczyńska, Karina; Cysewski, Piotr

2016-01-01

The possibility of molecular complex formation in the solid state of urea with benzoic acid analogues was measured directly on the crystallite films deposited on the glass surface using powder X-ray diffractometry (PXRD). Obtained solid mixtures were also analyzed using Fourier transform infrared spectroscopy (FTIR). The simple droplet evaporation method was found to be efficient, robust, fast and cost-preserving approach for first stage cocrystal screening. Additionally, the application of orientation effect to cocrystal screening simplifies the analysis due to damping of majority of diffraction signals coming from coformers. During validation phase the proposed approach successfully reproduced both positive cases of cocrystallization (urea:salicylic acid and urea:4-hydroxy benzoic acid) as well as pairs of co-formers immiscible in the solid state (urea:benzoic acid and urea:acetylsalicylic acids). Based on validated approach new cocrystals of urea were identified in complexes with 3-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid and 3,5-dihydroxybenzoic acid. In all cases formation of multicomponent crystal phase was confirmed by the appearance of new reflexes on the diffraction patterns and FTIR absorption band shifts of O-H and N-H groups.

Modification of solid-state property of sulfasalazine by using the supercritical antisolvent process

NASA Astrophysics Data System (ADS)

Wu, Wei-Yi; Su, Chie-Shaan

2017-02-01

In this study, the supercritical antisolvent (SAS) process was used to recrystallize an active pharmaceutical ingredient, sulfasalazine, to modify the solid-state properties including particle size, crystal habit and polymorphic form. Supercritical CO2 and tetrahydrofuran were used as the antisolvent and solvent, respectively. SAS results obtained from different operating temperatures (35, 45, 55 and 65 °C) were compared and discussed. The results indicate that at 55 °C, spherical sulfasalazine crystals were produced and that their mean particle size was micronized to approximately 1 μm. In addition, according to the analytical results of powder X-ray diffractometry (PXRD), a novel polymorphic form of sulfasalazine was obtained after SAS. Furthermore, the spectroscopic and thermal behavior of produced sulfasalazine crystals were also studied by Fourier transform infrared spectrometry (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Finally, SAS results obtained from different operating temperature was discussed on the basis of the mixture critical point (MCP) of CO2 and tetrahydrofuran. Operation at slightly higher than the MCP is favorable for recrystallization of sulfasalazine through SAS. These results demonstrate that the SAS process is an efficient tool for controlling and modifying the solid-state property of sulfasalazine.

Thermal decomposition of ammonium hexachloroosmate.

PubMed

Asanova, T I; Kantor, I; Asanov, I P; Korenev, S V; Yusenko, K V

2016-12-07

Structural changes of (NH 4 ) 2 [OsCl 6 ] occurring during thermal decomposition in a reduction atmosphere have been studied in situ using combined energy-dispersive X-ray absorption spectroscopy (ED-XAFS) and powder X-ray diffraction (PXRD). According to PXRD, (NH 4 ) 2 [OsCl 6 ] transforms directly to metallic Os without the formation of any crystalline intermediates but through a plateau where no reactions occur. XANES and EXAFS data by means of Multivariate Curve Resolution (MCR) analysis show that thermal decomposition occurs with the formation of an amorphous intermediate {OsCl 4 } x with a possible polymeric structure. Being revealed for the first time the intermediate was subjected to determine the local atomic structure around osmium. The thermal decomposition of hexachloroosmate is much more complex and occurs within a minimum two-step process, which has never been observed before.

A structural investigation into the compaction behavior of pharmaceutical composites using powder X-ray diffraction and total scattering analysis.

PubMed

Moore, Michael D; Steinbach, Alison M; Buckner, Ira S; Wildfong, Peter L D

2009-11-01

To use advanced powder X-ray diffraction (PXRD) to characterize the structure of anhydrous theophylline following compaction, alone, and as part of a binary mixture with either alpha-lactose monohydrate or microcrystalline cellulose. Compacts formed from (1) pure theophylline and (2) each type of binary mixture were analyzed intact using PXRD. A novel mathematical technique was used to accurately separate multi-component diffraction patterns. The pair distribution function (PDF) of isolated theophylline diffraction data was employed to assess structural differences induced by consolidation and evaluated by principal components analysis (PCA). Changes induced in PXRD patterns by increasing compaction pressure were amplified by the PDF. Simulated data suggest PDF dampening is attributable to molecular deviations from average crystalline position. Samples compacted at different pressures were identified and differentiated using PCA. Samples compacted at common pressures exhibited similar inter-atomic correlations, where excipient concentration factored in the analyses involving lactose. Practical real-space structural analysis of PXRD data by PDF was accomplished for intact, compacted crystalline drug with and without excipient. PCA was used to compare multiple PDFs and successfully differentiated pattern changes consistent with compaction-induced disordering of theophylline as a single component and in the presence of another material.

Characterization of two polymorphs of salmeterol xinafoate crystallized from supercritical fluids.

PubMed

Tong, H H; Shekunov, B Y; York, P; Chow, A H

2001-06-01

To characterize two polymorphs of salmeterol xinafoate (SX-I and SX-II) produced by supercritical fluid crystallization. SX-I and SX-II were crystallized as fine powders using Solution Enhanced Dispersion by Supercritical Fluids (SEDS). The two polymorphs and a reference micronized SX sample (MSX) were characterized using powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), aqueous solubility (and dissolution) determination at 5-40 degrees C, BET adsorption analysis, and inverse gas chromatography (IGC). Compared with SX-I, SX-II exhibited a lower enthalpy of fusion, a higher equilibrium solubility, a higher intrinsic dissolution rate, a lower enthalpy of solution (based on van't Hoff solubility plots), and a different FTIR spectrum (reflecting differences in intermolecular hydrogen bonding). Solubility ratio plot yielded a transition temperature (-99 degrees C) below the melting points of both polymorphs. MSX showed essentially the same crystal form as SX-I (confirmed by PXRD and FTIR), but a distinctly different thermal behaviour. Mild trituration of SX-I afforded a similar DSC profile to MSX while prolonged grinding of SX-I gave rise to an endotherm at -109 degrees C, corresponding to solid-solid transition of SX-I to SX-II. Surface analysis of MSX, SX-I, and SX-II by IGC revealed significant differences in surface free energy in terms of both dispersive (nonpolar) interactions and specific (polar) acid-base properties. The SEDS-processed SX-I and SX-II display high polymorphic purity and distinctly different physical and surface properties. The polymorphs are related enantiotropically with SX-I being the thermodynamically stable form at room temperature.

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.

Probing the evolution of palladium species in Pd@MOF catalysts during the Heck coupling reaction: An operando X-ray absorption spectroscopy study.

PubMed

Yuan, Ning; Pascanu, Vlad; Huang, Zhehao; Valiente, Alejandro; Heidenreich, Niclas; Leubner, Sebastian; Inge, A Ken; Gaar, Jakob; Stock, Norbert; Persson, Ingmar; Martin-Matute, Belen; Zou, Xiaodong

2018-06-11

The mechanism of the Heck C-C coupling reaction catalyzed by Pd@MOFs has been investigated using operando X-ray absorption spectroscopy (XAS) and powder X-ray diffraction (PXRD) combined with transmission electron microscopy (TEM) analysis and nuclear magnetic resonance ( 1 H NMR) kinetic studies. A custom-made reaction cell was used allowing operando PXRD and XAS data collection using high-energy synchrotron radiation. By analyzing the XAS data in combination with ex situ studies, the evolution of the palladium species is followed from the as-synthesized to its deactivated form. An adaptive reaction mechanism is pro-posed. Mononuclear Pd(II) complexes are found to be the dominant active species at the beginning of the reaction, which then gradually transform into Pd nanoclusters with 13-20 Pd atoms on average in later catalytic turnovers. Consumption of available reagent and substrate leads to coordination of Cl - ions to their surfaces, which causes the poisoning of the active sites. By understanding the deactivation process, it was possible to tune the reaction conditions and prolong the lifetime of the catalyst.

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.

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

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.

Solid-State Characterization and Relative Formation Enthalpies To Evaluate Stability of Cocrystals of an Antidiabetic Drug.

PubMed

Duggirala, Naga Kiran; Frericks Schmidt, Heather L; Lei, Zhaohui; Zaworotko, Michael J; Krzyzaniak, Joseph F; Arora, Kapildev K

2018-05-07

The current study integrates formation enthalpy and traditional slurry experiments to quickly assess the physical stability of cocrystal drug substance candidates for their potential to support drug development. Cocrystals of an antidiabetic drug (GKA) with nicotinamide (NMA), vanillic acid (VLA), and ethyl vanillin (EVL) were prepared and characterized by powder X-ray diffractometry (PXRD), spectroscopic, and thermal techniques. The formation enthalpies of the cocrystals, and their physical mixtures (GKA + coformer) were measured by the differential scanning calorimetry (DSC) method reported by Zhang et al. [ Cryst. Growth Des. 2012 , 12 ( 8 ), 4090 - 4097 ]. The experimentally measured differences in the relative formation enthalpies obtained by integrating the heat flow of each cocrystal against the respective physical mixture were correlated to the physical stability of the cocrystals in the solid state. The relative formation enthalpies of all of the cocrystals studied suggest that the cocrystals are not physically stable at room temperature versus their physical mixtures. To further address relative stability, the cocrystals were slurried in 30% v/v aqueous ethanol, and it was observed that all of the cocrystals revert to GKA within 48 h at room temperature. The slurry experiments are consistent with the relative instability of the cocrystals with respect to their physical mixtures suggested by the DSC results.

Parts per Million Powder X-ray Diffraction

DOE PAGES

Newman, Justin A.; Schmitt, Paul D.; Toth, Scott J.; ...

2015-10-14

Here in this paper we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect lowmore » crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.« less

Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazole

NASA Astrophysics Data System (ADS)

Kürkçüoğlu, Güneş Süheyla; Kiraz, Fulya Çetinkaya; Sayın, Elvan

2015-10-01

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbreviated as M-Ni-etim, M = Mn(II), Fe(II) or Co(II); etim = 1-ethylimidazole, C5H8N2) were prepared in powder form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal (TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were elucidated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide a better understanding of the structures. It is shown that the spectra are consistent with a proposed crystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrational spectra of the complexes were presented and discussed with respect to the internal modes of both the etim and the cyanide ligands. The C, H and N analyses were carried out for all the complexes. Thermal behaviors of these complexes were followed using TG, DTG and DTA curves in the temperature range 30-700 °C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powder X-ray analyses revealed no significant differences between the single crystal and powder forms. Additionally, electrical and magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopy, PXRD, thermal and elemental analyses results propose that these complexes are similar in structure to the Hofmann-type complexes.

In Situ Investigation of a Self-Accelerated Cocrystal Formation by Grinding Pyrazinamide with Oxalic Acid.

PubMed

Kulla, Hannes; Greiser, Sebastian; Benemann, Sigrid; Rademann, Klaus; Emmerling, Franziska

2016-07-14

A new cocrystal of pyrazinamide with oxalic acid was prepared mechanochemically and characterized by PXRD, Raman spectroscopy, solid-state NMR spectroscopy, DTA-TG, and SEM. Based on powder X-ray diffraction data the structure was solved. The formation pathway of the reaction was studied in situ using combined synchrotron PXRD and Raman spectroscopy. Using oxalic acid dihydrate the initially neat grinding turned into a rapid self-accelerated liquid-assisted grinding process by the release of crystallization water. Under these conditions, the cocrystal was formed directly within two minutes.

Copper doped TiO2 nanoparticles characterized by X-ray absorption spectroscopy, total scattering, and powder diffraction--a benchmark structure-property study.

PubMed

Lock, Nina; Jensen, Ellen M L; Mi, Jianli; Mamakhel, Aref; Norén, Katarina; Qingbo, Meng; Iversen, Bo B

2013-07-14

Metal functionalized nanoparticles potentially have improved properties e.g. in catalytic applications, but their precise structures are often very challenging to determine. Here we report a structural benchmark study based on tetragonal anatase TiO2 nanoparticles containing 0-2 wt% copper. The particles were synthesized by continuous flow synthesis under supercritical water-isopropanol conditions. Size determination using synchrotron PXRD, TEM, and X-ray total scattering reveals 5-7 nm monodisperse particles. The precise dopant structure and thermal stability of the highly crystalline powders were characterized by X-ray absorption spectroscopy and multi-temperature synchrotron PXRD (300-1000 K). The combined evidence reveals that copper is present as a dopant on the particle surfaces, most likely in an amorphous oxide or hydroxide shell. UV-VIS spectroscopy shows that copper presence at concentrations higher than 0.3 wt% lowers the band gap energy. The particles are unaffected by heating to 600 K, while growth and partial transformation to rutile TiO2 occur at higher temperatures. Anisotropic unit cell behavior of anatase is observed as a consequence of the particle growth (a decreases and c increases).

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.

Powder X-ray diffraction method for the quantification of cocrystals in the crystallization mixture.

PubMed

Padrela, Luis; de Azevedo, Edmundo Gomes; Velaga, Sitaram P

2012-08-01

The solid state purity of cocrystals critically affects their performance. Thus, it is important to accurately quantify the purity of cocrystals in the final crystallization product. The aim of this study was to develop a powder X-ray diffraction (PXRD) quantification method for investigating the purity of cocrystals. The method developed was employed to study the formation of indomethacin-saccharin (IND-SAC) cocrystals by mechanochemical methods. Pure IND-SAC cocrystals were geometrically mixed with 1:1 w/w mixture of indomethacin/saccharin in various proportions. An accurately measured amount (550 mg) of the mixture was used for the PXRD measurements. The most intense, non-overlapping, characteristic diffraction peak of IND-SAC was used to construct the calibration curve in the range 0-100% (w/w). This calibration model was validated and used to monitor the formation of IND-SAC cocrystals by liquid-assisted grinding (LAG). The IND-SAC cocrystal calibration curve showed excellent linearity (R(2) = 0.9996) over the entire concentration range, displaying limit of detection (LOD) and limit of quantification (LOQ) values of 1.23% (w/w) and 3.74% (w/w), respectively. Validation results showed excellent correlations between actual and predicted concentrations of IND-SAC cocrystals (R(2) = 0.9981). The accuracy and reliability of the PXRD quantification method depend on the methods of sample preparation and handling. The crystallinity of the IND-SAC cocrystals was higher when larger amounts of methanol were used in the LAG method. The PXRD quantification method is suitable and reliable for verifying the purity of cocrystals in the final crystallization product.

Study of the specific features of single-crystal boron microstructure

NASA Astrophysics Data System (ADS)

Blagov, A. E.; Vasil'ev, A. L.; Dmitriev, V. P.; Ivanova, A. G.; Kulikov, A. G.; Marchenkov, N. V.; Popov, P. A.; Presnyakov, M. Yu.; Prosekov, P. A.; Pisarevskii, Yu. V.; Targonskii, A. V.; Chernaya, T. S.; Chernyshov, D. Yu.

2017-09-01

A complex study of the structure of β-boron single crystal grown by the floating-zone method, with sizes significantly exceeding the analogs known in the literature, has been performed. The study includes X-ray diffraction analysis and X-ray diffractometry (measurement of pole figures and rocking curves), performed on both laboratory and synchrotron sources; atomic-resolution scanning transmission electron microscopy with spherical aberration correction; and energy-dispersive microanalysis. X-ray diffraction analysis using synchrotron radiation has been used to refine the β-boron structure and find impurity Si atoms. The relative variations in the unit-cell parameters a and c for the crystal bulk are found to be δ a/ a ≈ 0.4 and δ c/ c ≈ 0.1%. X-ray diffractometry has revealed that the single-crystal growth axis coincides with the [2\\bar 2013] crystallographic axis and makes an angle of 21.12° with the [0001] threefold axis. Electron microscopy data have confirmed that the sample under study is a β-boron crystal, which may contain 0.3-0.4 at % Si as an impurity. Planar defects (stacking faults and dislocations) are found. The results of additional measurements of the temperature dependence of the thermal conductivity of the crystal in the range of 50-300 K are indicative of its high structural quality.

Investigating the effect of moisture protection on solid-state stability and dissolution of fenofibrate and ketoconazole solid dispersions using PXRD, HSDSC and Raman microscopy.

PubMed

Kanaujia, Parijat; Lau, Grace; Ng, Wai Kiong; Widjaja, Effendi; Schreyer, Martin; Hanefeld, Andrea; Fischbach, Matthias; Saal, Christoph; Maio, Mario; Tan, Reginald B H

2011-09-01

Enhanced dissolution of poorly soluble active pharmaceutical ingredients (APIs) in amorphous solid dispersions often diminishes during storage due to moisture-induced re-crystallization. This study aims to investigate the influence of moisture protection on solid-state stability and dissolution profiles of melt-extruded fenofibrate (FF) and ketoconazole (KC) solid dispersions. Samples were kept in open, closed and Activ-vials(®) to control the moisture uptake under accelerated conditions. During 13-week storage, changes in API crystallinity were quantified using powder X-ray diffraction (PXRD) (Rietveld analysis) and high sensitivity differential scanning calorimetry (HSDSC) and compared with any change in dissolution profiles. Trace crystallinity was observed by Raman microscopy, which otherwise was undetected by PXRD and HSDSC. Results showed that while moisture protection was ineffective in preventing the re-crystallization of amorphous FF, KC remained X-ray amorphous despite 5% moisture uptake. Regardless of the degree of crystallinity increase in FF, the enhanced dissolution properties were similarly diminished. Moisture uptake above 10% in KC samples also led to re-crystallization and significant decrease in dissolution rates. In conclusion, eliminating moisture sorption may not be sufficient in ensuring the stability of solid dispersions. Analytical quantification of API crystallinity is crucial in detecting subtle increase in crystallinity that can diminish the enhanced dissolution properties of solid dispersions.

Three pharmaceuticals cocrystals of adefovir: Syntheses, structures and dissolution study

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Sun, Fuxing; Zhang, Tingting; Jia, Jiangtao; Su, Hongmin; Wang, Chenhui; Zhu, Guangshan

2015-11-01

We report here three novel cocrystals, which are composed of adefovir as the API (Active Pharmaceutical Ingredient) with p-aminobenzoic acid (1, 2C8H12N5O4P·C7H6NO2·3H2O), 3,5-dihydroxybenzoic acid (2, C8H12N5O4P·C7H6O4·H2O) and 2,6-pyridinedicarboxlic acid (3, C8H12N5O4P·C7H5NO4) as CCFs (cocrystal formers) respectively by crystal engineering strategy. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), elemental analysis (EA) and infrared spectral analysis (IR). The analysis of single crystal X-ray diffraction demonstrate that cocrystal 1 and 2 form a strong hydrogen-bonded assembly through the phosphoric acids of API with water in the lattice and carboxylic acids of CCF respectively. Cocrystal 3 is formed in which the phosphoric acid groups of API are also held by the carboxylic acid groups of CCF. The PXRD results indicate their high purity of as-synthesized samples. The TGA, EA, IR and dissolution study of API and the cocrystals were also measured and discussed.

Synthesis, characterization and dissolution of three pharmaceutical cocrystals based on deferiprone

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Tian, Yuyang; Jia, Jiangtao; Zhang, Tingting; Zhu, Guangshan

2016-03-01

In this paper we present three new cocrystals based on deferiprone which is the first oral medicine as iron chelator. Solitary deferiprone possesses some known problems due to its good solubility and frequent dosing side effects. For these three novel co crystals, deferiprone is the active pharmaceutical ingredient (API), p-hydroxybenzoic acid (1, C7H9NO2·C7H6O3), 2, 5-dihydroxybenzoic acid (2, C7H9NO2·C7H6O4) and maleic acid (3, C7H9NO2·C4H4O4) are used as cocrystal formers (CCFs), respectively. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), differential thermal analysis (DTA), elemental analysis (EA) and infrared spectral analysis (IR). Single crystal X-ray diffraction demonstrates that all three cocrystals (1-3) possess strong hydrogen-bondings assembled through hydroxyl of API and carboxylic acids of CCFs. The PXRD results indicate their high purity of as-synthesized samples. TGA, DTA, EA, IR and dissolution study of API and cocrystals were also measured and discussed, respectively. The results suggest that the cocrystals exhibit low dissolution rates comparing with solitary deferiprone, which is very advantageous for the oral medicine with frequent dosing side effects.

High-throughput continuous hydrothermal synthesis of an entire nanoceramic phase diagram.

PubMed

Weng, Xiaole; Cockcroft, Jeremy K; Hyett, Geoffrey; Vickers, Martin; Boldrin, Paul; Tang, Chiu C; Thompson, Stephen P; Parker, Julia E; Knowles, Jonathan C; Rehman, Ihtesham; Parkin, Ivan; Evans, Julian R G; Darr, Jawwad A

2009-01-01

A novel High-Throughput Continuous Hydrothermal (HiTCH) flow synthesis reactor was used to make directly and rapidly a 66-sample nanoparticle library (entire phase diagram) of nanocrystalline Ce(x)Zr(y)Y(z)O(2-delta) in less than 12 h. High resolution PXRD data were obtained for the entire heat-treated library (at 1000 degrees C/1 h) in less than a day using the new robotic beamline I11, located at Diamond Light Source (DLS). This allowed Rietveld-quality powder X-ray diffraction (PXRD) data collection of the entire 66-sample library in <1 day. Consequently, the authors rapidly mapped out phase behavior and sintering behaviors for the entire library. Out of the entire 66-sample heat-treated library, the PXRD data suggests that 43 possess the fluorite structure, of which 30 (out of 36) are ternary compositions. The speed, quantity and quality of data obtained by our new approach, offers an exciting new development which will allow structure-property relationships to be accessed for nanoceramics in much shorter time periods.

Detecting phase separation of freeze-dried binary amorphous systems using pair-wise distribution function and multivariate data analysis.

PubMed

Chieng, Norman; Trnka, Hjalte; Boetker, Johan; Pikal, Michael; Rantanen, Jukka; Grohganz, Holger

2013-09-15

The purpose of this study is to investigate the use of multivariate data analysis for powder X-ray diffraction-pair-wise distribution function (PXRD-PDF) data to detect phase separation in freeze-dried binary amorphous systems. Polymer-polymer and polymer-sugar binary systems at various ratios were freeze-dried. All samples were analyzed by PXRD, transformed to PDF and analyzed by principal component analysis (PCA). These results were validated by differential scanning calorimetry (DSC) through characterization of glass transition of the maximally freeze-concentrate solute (Tg'). Analysis of PXRD-PDF data using PCA provides a more clear 'miscible' or 'phase separated' interpretation through the distribution pattern of samples on a score plot presentation compared to residual plot method. In a phase separated system, samples were found to be evenly distributed around the theoretical PDF profile. For systems that were miscible, a clear deviation of samples away from the theoretical PDF profile was observed. Moreover, PCA analysis allows simultaneous analysis of replicate samples. Comparatively, the phase behavior analysis from PXRD-PDF-PCA method was in agreement with the DSC results. Overall, the combined PXRD-PDF-PCA approach improves the clarity of the PXRD-PDF results and can be used as an alternative explorative data analytical tool in detecting phase separation in freeze-dried binary amorphous systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Dehydration of detomidine hydrochloride monohydrate.

PubMed

Veldre, K; Actiņš, A; Jaunbergs, J

2011-10-09

The thermodynamic stability of detomidine hydrochloride monohydrate has been evaluated on the basis of phase transition kinetics in solid state. A method free of empirical models was used for the treatment of kinetic data, and compared to several known solid state kinetic data processing methods. Phase transitions were monitored by powder X-ray diffraction (PXRD) and thermal analysis. Full PXRD profiles were used for determining the phase content instead of single reflex intensity measurements, in order to minimize the influence of particle texture. We compared the applicability of isothermal and nonisothermal methods to our investigation of detomidine hydrochlorine monohydrate dehydration. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

Processing of copper converter slag for metals reclamation: Part II: mineralogical study.

PubMed

Deng, Tong; Ling, Yunhan

2004-10-01

Chemical and mineralogical characterizations of a copper converter slag, and its products obtained by curing with strong sulphuric acid and leaching with hot water, were carried out using ore microscopy, scanning electronic microscopy with energy dispersive spectrometry, wave-length dispersive X-ray fluorescence spectrometry, X-ray diffractometry and chemical phase analysis, which provided necessary information to develop a new process for treating such slag and further understanding of the chemical and mineralogical changes in the process.

Time-dependent gel to gel transformation of a peptide based supramolecular gelator.

PubMed

Baral, Abhishek; Basak, Shibaji; Basu, Kingshuk; Dehsorkhi, Ashkan; Hamley, Ian W; Banerjee, Arindam

2015-06-28

A dipeptide with a long fatty acid chain at its N-terminus gives hydrogels in phosphate buffer in the pH range 7.0-8.5. The hydrogel with a gelator concentration of 0.45% (w/v) at pH 7.46 (physiological pH) provides a very good platform to study dynamic changes within a supramolecular framework as it exhibits remarkable change in its appearance with time. Interestingly, the first formed transparent hydrogel gradually transforms into a turbid gel within 2 days. These two forms of the hydrogel have been thoroughly investigated by using small angle X-ray scattering (SAXS), powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FE-SEM) and high-resolution transmission electron microscopic (HR-TEM) imaging, FT-IR and rheometric analyses. The SAXS and low angle PXRD studies substantiate different packing arrangements for the gelator molecules for these two different gel states (the freshly prepared and the aged hydrogel). Moreover, rheological studies of these two gels reveal that the aged gel is stiffer than the freshly prepared gel.

A Green Protocol for Synthesis of MAl2O4, [M=Cu and Co] Spinels Under Microwave Irradiation Method

NASA Astrophysics Data System (ADS)

Yuvasravana, R.; George, P. P.

Nanosized metal aluminates MAl2O4, [M=Cu and Co] are synthesized from their nitrates solution by using pomegranate peel extract as fuel in microwave combustion. MAl2O4 [M=Cu and Co] nanoparticles are grown in microwave assisted synthesis followed by annealing at 700∘C. The nanoparticles have been characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-VIS spectroscopy and photoluminescence (PL) spectroscopy. The PXRD analysis has confirmed their spinel composition. The green protocol and microwave combustion route for spinel synthesis are rapid, simple, without any hazardous chemicals as reducing or stabilizing agents and economical.

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.

New metastable form of glibenclamide prepared by redispersion from ternary solid dispersions containing polyvinylpyrrolidone-K30 and sodium lauryl sulfate.

PubMed

Thongnopkoon, Thanu; Puttipipatkhachorn, Satit

2016-01-01

Modification of polymorphic forms of poorly water-soluble drugs is one way to achieve the desirable properties. In this study, glibenclamide (GBM) particles with different polymorphic forms, including a new metastable form, were obtained from redispersion of ternary solid dispersion systems. The ternary solid dispersion systems, consisting of GBM, polyvinylpyrrolidone-K30 (PVP-K30) and sodium lauryl sulfate (SLS), were prepared by solvent evaporation method and subsequently redispersed in deionized water. The precipitated drug particles were then collected at a given time period. The drug particles with different polymorphic forms could be achieved depending on the polymer/surfactant ratio. Amorphous drug nanoparticles could be obtained by using a high polymer/surfactant ratio, whereas two different crystalline forms were obtained from the systems containing low polymer/surfactant ratios. Interestingly, a new metastable form IV of GBM with improved dissolution behavior could be obtained from the system of GBM:PVP-K30:SLS with the weight ratio of 2:2:4. This new polymorphic form IV of GBM was confirmed by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffractometry (PXRD) and solid state 13 C nuclear magnetic resonance (NMR) spectroscopy. The molecular arrangement of the new polymorphic form IV of GBM was proposed. The GBM particles with polymorphic form IV also showed an improved dissolution behavior. In addition, it was found that the formation of the new polymorphic form IV of GBM by this process was reproducible.

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.

Physical solid-state properties and dissolution of sustained-release matrices of polyvinylacetate.

PubMed

Gonzalez Novoa, Gelsys Ananay; Heinämäki, Jyrki; Mirza, Sabir; Antikainen, Osmo; Colarte, Antonio Iraizoz; Paz, Alberto Suzarte; Yliruusi, Jouko

2005-02-01

Solid-state compatibility and in vitro dissolution of direct-compressed sustained-release matrices of polyvinylacetate (PVAc) and polyvinylpyrrolidone (PVP) containing ibuprofen as a model drug were studied. Polyvinylalcohol (PVA) was used as an alternative water-soluble polymer to PVP. Differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) were used for characterizing solid-state polymer-polymer and drug-polymer interactions. The mechanical treatment for preparing physical mixtures of polyvinyl polymers and the drug (i.e. simple blending or stressed cogrinding) was shown not to affect the physical state of the drug and the polymers. With the drug-polymer mixtures the endothermic effect due to drug melting was always evident, but a considerable modification of the melting point of the drug in physical binary mixtures (drug:PVP) was observed, suggesting some interaction between the two. On the other hand, the lack of a significant shift of the melting endothermic peak of the drug in physical tertiary drug-polymer mixtures revealed no evidence of solid-state interaction between the drug and the present polymers. Sustained-release dissolution profiles were achieved from the direct-compressed matrices made from powder mixtures of the drug and PVAc combined with PVP, and the proportion of PVAc in the mixture clearly altered the drug release profiles in vitro. The drug release from the present matrix systems is controlled by both diffusion of the drug through the hydrate matrix and the erosion of the matrix itself.

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.

Portable X-ray powder diffractometer for the analysis of art and archaeological materials

NASA Astrophysics Data System (ADS)

Nakai, Izumi; Abe, Yoshinari

2012-02-01

Phase identification based on nondestructive analytical techniques using portable equipment is ideal for the analysis of art and archaeological objects. Portable(p)-XRF and p-Raman are very widely used for this purpose, yet p-XRD is relatively rare despite its importance for the analysis of crystalline materials. This paper overviews 6 types of p-XRD systems developed for analysis of art and archaeological materials. The characteristics of each system are compared. One of the p-XRD systems developed by the authors was brought to many museums as well as many archeological sites in Egypt and Syria to characterize the cultural heritage artifacts, e.g., amulet made of Egyptian blue, blue painted pottery, and Islamic pottery from Egypt, jade from China, variscite from Syria, a Japanese classic painting drawn by Korin Ogata, and oil paintings drawn by Taro Okamoto. Practical application data are shown to demonstrate the potential ability of the method for analysis of various art and archaeological materials.

Zinc-doped cerium oxide nanoparticles: Sol-gel synthesis, characterization, and investigation of their in vitro cytotoxicity effects

NASA Astrophysics Data System (ADS)

Akbari, Alireza; Khammar, Mansoureh; Taherzadeh, Danial; Rajabian, Arezoo; Khorsand Zak, Ali; Darroudi, Majid

2017-12-01

Zinc-doped cerium oxide nanoparticles (Zn-doped CeO2-NPs) with Ce1-xZnxO2 composition, where x equals to 0.0, 0.01, 0.03, and 0.05 are synthesized through a green based sol-gel method from nitrate precursors and gelatin at the fixed calcination temperature of 600 °C maintained for 2 h. The powder X-ray diffraction (PXRD) patterns displayed the single-crystalline structure of these particular samples, which seemed to be completely indexed with the cubic fluorite phase. The evolution of crystalline phases in Ce1-xZnxO2 are assured by the observed broadening in PXRD peaks, while the field emission scanning electron microscopy (FE-SEM) images revealed that the spherical-shaped single-crystalline NPs do exist and confirmed the size estimations that were obtained from the Scherrer's equation. A dose dependent toxicity with non-toxic effects of concentrations up to 31.25 μg/ml is illustrated through the In vitro cytotoxicity studies regarding Neuro2A cells.

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.

Pulsed supercritical synthesis of anatase TiO₂ nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction.

PubMed

Rostgaard Eltzholtz, Jakob; Tyrsted, Christoffer; Ørnsbjerg Jensen, Kirsten Marie; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Brummerstedt Iversen, Bo

2013-03-21

A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol(-1) for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.

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.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Nanometric MgFe2O4: Synthesis, characterization and its application towards supercapacitor and electrochemical uric acid sensor

NASA Astrophysics Data System (ADS)

Majumder, S.; Kumar, S.; Banerjee, S.

2017-05-01

In this paper, we have synthesized nanocrystalline MgFe2O4 (S1) by auto-combustion assisted sol-gel method. The structure and morphology and elemental study of S1 are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM) and energy dispersive X-ray spectroscopic (EDS) techniques. The FESEM images reveal that the morphology of the sample is rough and average particle size is 50 nm. The PXRD study indicates that the samples are well crystalline and single phase in nature. Moreover, we have performed supercapacitor study by electrochemical galvanostatic charge-discharge (GCD) measurement, which shows pseudo capacitive behavior. S1 contains a high specific capacitance of 428.9 Fg-1 at the current density 0.0625 Ag-1 and can deliver high energy and power density of 18.01 Wh kg-1 and 21468 Wkg-1 respectively. Moreover, uric acid (UA) sensing study has also been performed by cyclic voltmetry (CV) and electrochemical impedance spectroscopy measurement (EIS) of S1. We can use nanocrystalline MgFe2O4 as supercapacitor and UA sensor applications purpose.

Mechanochemical synthesis and structural characterization of three novel cocrystals of dimethylglyoxime with N-heterocyclic aromatic compounds and acetamide

NASA Astrophysics Data System (ADS)

Abidi, Syed Sibte Asghar; Azim, Yasser; Gupta, Abhishek Kumar; Pradeep, Chullikkattil P.

2017-12-01

With an aim to explore the interactions of (RR'Cdbnd Nsbnd OH) oxime moiety of dimethylglyoxime (DMG) with pyridyl ring of N-heterocyclic aromatic compounds and acetamide, three novel cocrystals of dimethylglyoxime with acridine (ACR), 1,10-phenanthroline monohydrate (PT) and acetamide (ACT) are reported. These three cocrystals were obtained with a mechanochemical synthesis approach and were characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), fourier transform-infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, Hirshfeld surface analysis is used to investigate the intermolecular interaction and the crystal packing of cocrystals.

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.

Synthesis, characterization and photoluminescence properties of Bi³⁺ co-doped CaSiO₃:Eu³⁺ nanophosphor.

PubMed

Kumar, M Madesh; Krishna, R Hari; Nagabhushana, B M; Shivakumara, C

2015-03-15

Ceramic luminescent powders with the composition Ca(0.96-x)Eu0.04Bi(x)SiO3 (x=0.01-0.05) were prepared by solution combustion method. The nanopowders are characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) techniques. PXRD patterns of calcined (950°C for 3h) Ca(0.96-x)Eu0.04Bi(x)SiO3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 28 to 48 nm. SEM micrographs show the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. TEM micrograph shows the crystalline characteristics of the nanoparticles. Upon 280 nm excitation, the photoluminescence of the Ca(0.96-x)Eu0.04Bi(x)SiO3 particles show red emission at 611 nm corresponding to 5D0→7F2 transition. It is observed that PL intensity increases with Bi(3+) concentration. Our work demonstrates very interesting energy transfer from Bi(3+) to Eu(3+) in CaSiO3 host. Copyright © 2014 Elsevier B.V. All rights reserved.

Syntheses, structures and luminescent properties of two novel Zn (II) coordination polymers

NASA Astrophysics Data System (ADS)

Huang, Ya-Ru; Gao, Ling-Ling; Wang, Xiao-Qing; Fan, Li-Ming; Hu, Tuo-Ping

2018-02-01

Two new coordination polymers, namely [Zn(TZMB)]n (1) and {[Zn(TZMB)](H2TZMB)]·(C2H5OH)0.5(H2O)2.5}n (2), (H2TZMB = 4,4‧-(1H-1,2,4-triazol-1-yl)methylene-bis(benzonic acid), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction analysis, elemental analysis (EA), IR spectrum analysis (IR), powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Single X-ray diffraction analysis reveals that complex 1 is a 3D 3,6-connected net with the point symbol of (6110.84)(63)2 and complex 2 is a 2D 3-connected net with the point symbol of (63). Furthermore, luminescent properties of complexes 1 and 2 were also investigated in detail.

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.

Evolution of Constitution, Structure, and Morphology in FeCo-Based Multicomponent Alloys

NASA Astrophysics Data System (ADS)

Li, R.; Stoica, M.; Liu, G.; Eckert, J.

2010-07-01

Constituent phases, melting behaviors, and microstructure of multicomponent (Fe0.5Co0.5) x (Mo0.1C0.2B0.5Si0.2)100- x alloys ( x = 95, 90, 85, 80, and 70) produced by copper mold casting were evaluated by various analysis techniques, i.e., X-ray diffractometry, scanning electronic microscopy with energy dispersive X-ray spectrometry, and differential scanning calorimetry. Metastable Fe3C- and Cr23C6-type phases were identified in the chill-cast alloys. A schematic illustration was proposed to explain the evolution of constituent phases and microstructure for the alloys with x = 95, 90, and 85 during the solidification process, which could be applicable to controlling microstructural formation of other multicomponent alloys with similar microstructures by artificially adjusting the composition.

Application of powder X-ray diffraction in studying the compaction behavior of bulk pharmaceutical powders.

PubMed

Bandyopadhyay, Rebanta; Selbo, Jon; Amidon, Gregory E; Hawley, Michael

2005-11-01

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds.

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

Evaluation of physicochemical properties and in vivo efficiency of atorvastatin calcium/ezetimibe solid dispersions.

PubMed

Jahangiri, Azin; Barzegar-Jalali, Mohammad; Garjani, Alireza; Javadzadeh, Yousef; Hamishehkar, Hamed; Asadpour-Zeynali, Karim; Adibkia, Khosro

2016-01-20

Fixed-dose combination of atorvastatin calcium (ATV) and ezetimibe (EZT) provides a considerable advantage in the management of hyperlipidemia. However, both ATV and EZT suffer from the poor aqueous solubility, which can limit their oral bioavailability. The aim of the present study was to improve the in vitro performance and evaluate the in vivo efficiency of the improved (ATV/EZT) fixed-dose combination. The formulation was prepared through solid dispersion (SD)technique, using Polyvinylpyrrolidone K30 via solvent method. Solid-state analysis and the in vitro drug release of the prepared formulations were also assessed. In order to estimate the therapeutic efficiency of the prepared SDs, in vivo studies including measurement of serum lipid levels, liver index and histological analysis of the liver tissue in hyperlipidemic rats were conducted. Differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) showed that the drugs crystallinity was notably decreased during the preparation process. All SDs showed enhanced release for both drugs compared to their binary mixture, drugs: polymer physical mixtures (PMs) and marketed product. Administration of ATV/EZT SD led to a remarkable decrease (P<0.05) in the serum levels of total cholesterol (TC) and LDL-C in the high fat diet-induced hyperlipidemic rats compared to the PM. Additionally, the histopathological examination of the liver tissue revealed the improved efficiency of the SDs on the liver steatosis. According to the obtained results, ATV/EZT SD with improved physicochemical characteristics, showed favorable effects on the serum lipid levels and liver steatosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of titanium on the structural and optical property of NiO nano powders

NASA Astrophysics Data System (ADS)

Amin, Ruhul; Mishra, Prashant; Khatun, Nasima; Ayaz, Saniya; Srivastava, Tulika; Sen, Somaditya

2018-05-01

Nickel Oxide (NiO) and Ti doped NiO nanoparticles were prepared by sol-gel auto combustion method. Powder x-ray diffraction (PXRD) structural studies revealed face centered cubic (FCC) structure of the NiO nanopowders. The crystallite size decreased with Ti incorporation. UV-Vis spectroscopy carried out in diffused reflectance mode revealed decrease in band gap with increment in Urbach energy with doping.

Analysis of a nanocrystalline polymer dispersion of ebselen using solid-state NMR, Raman microscopy, and powder X-ray diffraction.

PubMed

Vogt, Frederick G; Williams, Glenn R

2012-07-01

Nanocrystalline drug-polymer dispersions are of significant interest in pharmaceutical delivery. The purpose of this work is to demonstrate the applicability of methods based on two-dimensional (2D) and multinuclear solid-state NMR (SSNMR) to a novel nanocrystalline pharmaceutical dispersion of ebselen with polyvinylpyrrolidone-vinyl acetate (PVP-VA), after initial characterization with other techniques. A nanocrystalline dispersion of ebselen with PVP-VA was prepared and characterized by powder X-ray diffraction (PXRD), confocal Raman microscopy and mapping, and differential scanning calorimetry (DSC), and then subjected to detailed 1D and 2D SSNMR analysis involving ¹H, ¹³C, and ⁷⁷Se isotopes and ¹H spin diffusion. PXRD was used to show that dispersion contains nanocrystalline ebselen in the 35-60 nm size range. Confocal Raman microscopy and spectral mapping were able to detect regions where short-range interactions may occur between ebselen and PVP-VA. Spin diffusion effects were analyzed using 2D SSNMR experiments and are able to directly detect interactions between ebselen and the surrounding PVP-VA. The methods used here, particularly the 2D SSNMR methods based on spin diffusion, provided detailed structural information about a nanocrystalline polymer dispersion of ebselen, and should be useful in other studies of these types of materials.

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.

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...

Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

NASA Astrophysics Data System (ADS)

Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai

2016-11-01

Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag-ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag-ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag-ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

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

Newman, Justin A.; Schmitt, Paul D.; Toth, Scott J.

Here in this paper we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect lowmore » crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.« less

Study on photocatalytic activity of nanosized Co0.3Zn0.7Fe2O4 synthesized by hydrothermal method

NASA Astrophysics Data System (ADS)

Mondal, R.; Sarkar, K.; Dey, S.; Bhattacharjee, S.; Ghosh, C. K.; Kumar, S.

2018-04-01

We have reported the photocatalytic activity of nanosized Co0.3Zn0.7Fe2O4 (CZM) synthesized by hydrothermal method. Powder x-ray diffraction (PXRD), field emission and transmission electron microscopic techniques have been employed for structural and microstructural characterization of the sample. The Rietveld refinement of the PXRD pattern of CZM reveals that the sample is a single phase spinel ferrite of F d 3 ¯m symmetry having crystallite size ˜ 20 nm. The average particle size is ˜ 23 nm. The photocatalytic study suggests that CZM can be suitably used as an efficient (rate constant and % degradation are 7.4×10-2 min-1, 95.76 % at 40 min, respectively), magnetically separable, recyclable photocatalyst for removal of Congo Red from its aqueous solution.

Leaching behavior and ESEM characterization of water-sensitive mudstone in southwestern Taiwan.

PubMed

Chen, Hung-Ta; Lin, Tzong-Tzeng; Chang, Juu-En

2003-05-01

This investigation attempts to understand the critical soluble salts in natural mudstone and the leaching, microstructural, and microchemical characteristics in soaked mudstone using scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDAX), X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), conductivity measurement, ion chromatography (IC), and environmental scanning electron microscopy (ESEM)/EDAX techniques. Natural mudstone probably includes soluble salts such as Na2SO4, NaCl, NaCO3, and CaCO3. The dissolution of Na2SO4 controls water-sensitive mudstone very susceptible to slaking and dispersion. ESEM micrographs clearly show evidence of mudstone-slaking during soaking since the visible pores are filled with small aggregative masses. A calcium-bearing precipitate from the soaked mudstone is speculated to be attributable to the decomposition of the hydrated product of the fresh mudstone.

Bimetal-organic frameworks for functionality optimization: MnFe-MOF-74 as a stable and efficient catalyst for the epoxidation of alkenes with H2O2.

PubMed

Yuan, Kuo; Song, Tianqun; Wang, Dawei; Zou, Ye; Li, Jinfeng; Zhang, Xiaotao; Tang, Zhiyong; Hu, Wenping

2018-01-25

In this work, we synthesized a series of microcrystalline Mn x N 100-x -MOF-74 (N = Fe, Co and Ni) materials by a one-pot reaction. Powder X-ray diffraction (PXRD) patterns of Mn x N 100-x -MOF-74 matched well with those of single-metal MOF-74, and the scanning electron microscopy (SEM) images exhibited homogeneous nanocrystallites aggregated together. The amounts and dispersion of metals were analyzed by using inductively coupled plasma (ICP) and energy-dispersive X-ray spectroscopy (EDS), separately. Mn x N 100-x -MOF-74 could remain crystalline and efficiently catalyze the epoxidation of alkenes in DMF with NaHCO 3 and 30% H 2 O 2 . In particular, Mn 29.39 Fe 70.61 -MOF-74 can achieve almost 100% conversion for styrene with 95.0% selectivity towards styrene oxide and be reused at least five times without loss of activity.

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

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

Inorganic fullerene-like tungsten disulfide nanocoating for friction reduction of nickel-titanium alloys.

PubMed

Samorodnitzky-Naveh, Gili R; Redlich, Meir; Rapoport, Lev; Feldman, Yishay; Tenne, Reshef

2009-12-01

To fabricate a friction-reducing coating onto different nickel-titanium (NiTi) substrates using inorganic fullerene-like tungsten disulfide (IF-WS(2)) nanoparticles and to estimate in vitro friction reducing extent of the coating. Different NiTi substrates were coated with cobalt and IF-WS(2) nanoparticles film by the electrodeposition procedure. Coating composition analyses was made by scanning-electron microscopy, energy dispersive x-ray spectroscopy, x-ray powder diffractometry and x-ray photoelectron spectroscopy. Friction evaluation was carried out using standard tribological tests and an Instron system. Stable and well-adhered cobalt + IF-WS(2) coating of the NiTi substrates was obtained. Friction tests presented up to 66% reduction of the friction coefficient. NiTi alloy is widely used for many medical appliances; hence, this unique friction-reducing coating could be implemented to provide better manipulation and lower piercing rates.

Structural transformations of sVI tert-butylamine hydrates to sII binary hydrates with methane.

PubMed

Prasad, Pinnelli S R; Sugahara, Takeshi; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2009-10-22

Binary clathrate hydrates with methane (CH(4), 4.36 A) and tert-butylamine (t-BuNH(2), 6.72 A) as guest molecules were synthesized at different molar concentrations of t-BuNH(2) (1.00-9.31 mol %) with methane at 7.0 MPa and 250 K, and were characterized by powder X-ray diffraction (PXRD) and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed on pressurizing with methane. The PXRD showed sII signatures and the remnant sVI signatures were insignificant, implying the metastable nature of sVI binary hydrates. Raman spectroscopic data on these binary hydrates suggest that the methane molecules occupy the small cages and vacant large cages. The methane storage capacity in this system was nearly doubled to approximately 6.86 wt % for 5.56 mol % > t-BuNH(2) > 1.0 mol %.

Fine refinement of solid state structure of racemic form of phospho-tyrosine employing NMR Crystallography approach.

PubMed

Paluch, Piotr; Pawlak, Tomasz; Oszajca, Marcin; Lasocha, Wieslaw; Potrzebowski, Marek J

2015-02-01

We present step by step facets important in NMR Crystallography strategy employing O-phospho-dl-tyrosine as model sample. The significance of three major techniques being components of this approach: solid state NMR (SS NMR), X-ray diffraction of powdered sample (PXRD) and theoretical calculations (Gauge Invariant Projector Augmented Wave; GIPAW) is discussed. Each experimental technique provides different set of structural constraints. From the PXRD measurement the size of the unit cell, space group and roughly refined molecular structure are established. SS NMR provides information about content of crystallographic asymmetric unit, local geometry, molecular motion in the crystal lattice and hydrogen bonding pattern. GIPAW calculations are employed for validation of quality of elucidation and fine refinement of structure. Crystal and molecular structure of O-phospho-dl-tyrosine solved by NMR Crystallography is deposited at Cambridge Crystallographic Data Center under number CCDC 1005924. Copyright © 2014 Elsevier Inc. All rights reserved.

Preparation and characterization of 'green' hybrid clay-dye nanopigments

NASA Astrophysics Data System (ADS)

Kaya, Mehmet; Onganer, Yavuz; Tabak, Ahmet

2015-03-01

We obtained a low cost and abundant nanopigment material composed of Rhodamine B (Rh-B) organic dye compound and Unye bentonite (UB) clay from Turkey. The characterization of the nanopigment was investigated using scanning electron microscopy (SEM), particle size distribution, powder X-ray diffraction (PXRD), Fourier transformed infra-red spectroscopy (FT-IR) and thermal analysis techniques. According to the result of texture analyses, we showed that the particle size distribution (d: 0.5-mean distribution) of Rh-B/UB nanopigment material was around 100 nm diameter. It was also demonstrated that the samples had a particle size around nm diameter in SEM images. As seen in the PXRD and thermal analysis, there is a difference in basal spacing by 1.46° (2θ) and a higher mass loss by 7.80% in the temperature range 200-500 °C compared to the raw bentonite.

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.

Modelling Assisted Design and Synthesis of Highly Porous Materials for Chemical Adsorbents

DTIC Science & Technology

2010-10-01

two phases of crystal, a monoclinic phase within the solution, and after removal from solution a trigonal phase is obtained. The single crystal...days. Single crystal X-ray data showed there existed a monoclinic phase within the solution that, upon removal from solution, rapidly converted to a... monoclinic to trigonal upon desolvation, as the new peak which has emerged matches the simulated PXRD of the trigonal phase. Also, as the sample is

Quantification of febuxostat polymorphs using powder X-ray diffraction technique.

PubMed

Qiu, Jing-bo; Li, Gang; Sheng, Yue; Zhu, Mu-rong

2015-03-25

Febuxostat is a pharmaceutical compound with more than 20 polymorphs of which form A is most widely used and usually exists in a mixed polymorphic form with form G. In the present study, a quantification method for polymorphic form A and form G of febuxostat (FEB) has been developed using powder X-ray diffraction (PXRD). Prior to development of a quantification method, pure polymorphic form A and form G are characterized. A continuous scan with a scan rate of 3° min(-1) over an angular range of 3-40° 2θ is applied for the construction of the calibration curve using the characteristic peaks of form A at 12.78° 2θ (I/I0100%) and form G at 11.72° 2θ (I/I0100%). The linear regression analysis data for the calibration plots shows good linear relationship with R(2)=0.9985 with respect to peak area in the concentration range 10-60 wt.%. The method is validated for precision, recovery and ruggedness. The limits of detection and quantitation are 1.5% and 4.6%, respectively. The obtained results prove that the method is repeatable, sensitive and accurate. The proposed developed PXRD method can be applied for the quantitative analysis of mixtures of febuxostat polymorphs (forms A and G). Copyright © 2015 Elsevier B.V. All rights reserved.

Niclosamide methanol solvate and niclosamide hydrate: structure, solvent inclusion mode and implications for properties.

PubMed

Harriss, Bethany I; Wilson, Claire; Radosavljevic Evans, Ivana

2014-08-01

Structural studies have been carried out of two solid forms of niclosamide [5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide, NCL], a widely used anthelmintic drug, namely niclosamide methanol monosolvate, C13H8Cl2N2O4·CH3OH or NCL·MeOH, and niclosamide monohydrate, denoted HA. The structure of the methanol solvate obtained from single-crystal X-ray diffraction is reported for the first time, elucidating the key host-guest hydrogen-bonding interactions which lead to solvate formation. The essentially planar NCL host molecules interact via π-stacking and pack in a herringbone-type arrangement, giving rise to channels along the crystallographic a axis in which the methanol guest molecules are located. The methanol and NCL molecules interact via short O-H...O hydrogen bonds. Laboratory powder X-ray diffraction (PXRD) measurements reveal that the initially phase-pure NCL·MeOH solvate readily transforms into NCL monohydrate within hours under ambient conditions. PXRD further suggests that the NCL monohydrate, HA, is isostructural with the NCL·MeOH solvate. This is consistent with the facile transformation of the methanol solvate into the hydrate when stored in air. The crystal packing and the topology of guest-molecule inclusion are compared with those of other NCL solvates for which the crystal structures are known, giving a consistent picture which correlates well with known experimentally observed desolvation properties.

Enhanced oral bioavailability of felodipine by novel solid self-microemulsifying tablets.

PubMed

Jing, Boyu; Wang, Zhiyuan; Yang, Rui; Zheng, Xia; Zhao, Jia; Tang, Si; He, Zhonggui

2016-01-01

The novel self-microemulsifying (SME) tablets were developed to enhance the oral bioavailability of a poor water-soluble drug felodipine (FDP). Firstly, FDP was dissolved in the optimized liquid self-microemusifying drug delivery systems (SMEDDS) containing Miglyol® 812, Cremophor® RH 40, Tween 80 and Transcutol® P, and the mixture was solidified with porous silicon dioxide and crospovidone as adsorbents. Then after combining the solidified powders with other excipients, the solid SME tablets were prepared by wet granulation-compression method. The prepared tablets possessed satisfactory characterization; the droplet size of the SME tablets following self-emulsification in water was nearly equivalent to the liquid SMEDDS (68.4 ± 14.0 and 64.4 ± 12.0 nm); differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) analysis demonstrated that FDP in SME tablets had undergone a polymorphism transition from a crystal form to an amorphous state, which was further confirmed by transmission electron microscopy (TEM). A similar dissolution performance of SME tablets and liquid SMEDDS was also obtained under the sink condition (85% within 10 min), both significantly higher than commercial tablets. The oral bioavailability was evaluated for the SME tablets, liquid SMEDDS and commercial conventional tablets in the fasted beagle dogs. The AUC of FDP from the SME tablets was about 2-fold greater than that of conventional tablets, but no significant difference was found when compared with the liquid SMEDDS. Accordingly, these preliminary results suggest that this formulation approach offers a useful large-scale producing method to prepare the solid SME tablets from the liquid SMEDDS for oral bioavailability equivalent enhancement of poorly soluble FDP.

Fabrication of a novel scaffold of clotrimazole-microemulsion-containing nanofibers using an electrospinning process for oral candidiasis applications.

PubMed

Tonglairoum, Prasopchai; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Kaomongkolgit, Ruchadaporn; Opanasopit, Praneet

2015-02-01

Clotrimazole (CZ)-loaded microemulsion-containing nanofiber mats were developed as an alternative for oral candidiasis applications. The microemulsion was composed of oleic acid (O), Tween 80 (T80), and a co-surfactant such as benzyl alcohol (BzOH), ethyl alcohol (EtOH) or isopropyl alcohol (IPA). The nanofiber mats were obtained by electrospinning a blended solution of a CZ-loaded microemulsion and a mixed polymer solution of 2% (w/v) chitosan (CS) and 10% (w/v) polyvinyl alcohol (PVA) at a weight ratio of 30:70. The nanofiber mats were characterized using various analytical techniques. The entrapment efficiency, drug release, antifungal activity and cytotoxicity were investigated. The average diameter of the nanofiber mats was in the range of 105.91-125.56 nm. The differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) results revealed the amorphous state of the CZ-loaded microemulsions incorporated into the nanofiber mats. The entrapment efficiency of CZ in the mats was approximately 72.58-98.10%, depended on the microemulsion formulation. The release experiment demonstrated different CZ release characteristics from nanofiber mats prepared using different CZ-loaded microemulsions. The extent of drug release from the fiber mats at 4h was approximately 64.81-74.15%. The release kinetics appeared to follow Higuchi's model. In comparison with CZ lozenges (10mg), the nanofiber mats exhibited more rapid killing activity. Moreover, the nanofiber mats demonstrated desirable mucoadhesive properties and were safe for 2h. Therefore, the nanofiber mats have the potential to be promising candidates for oral candidiasis applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of polymer type and storage relative humidity on the kinetics of felodipine crystallization from amorphous solid dispersions.

PubMed

Rumondor, Alfred C F; Stanford, Lindsay A; Taylor, Lynne S

2009-12-01

The objective of this study was to investigate the effects of polymer type and storage relative humidity (RH) on the crystallization kinetics of felodipine from amorphous solid dispersions. Crystallization of the model drug felodipine from amorphous solid dispersion samples containing poly(vinyl pyrrolidone) (PVP) and hypromellose acetate succinate (HPMCAS) were evaluated. Samples at three different drug-polymer weight ratios (10, 25, and 50 wt. % polymer) were prepared and stored at six different RHs (0%, 32%, 52% or 66%, 75%, 86%, and 93%). Periodically, the fraction of the drug that had crystallized from the samples was quantified using powder X-ray diffractometry (PXRD). Felodipine crystallization rates from PVP-containing dispersions were found to be very sensitive to changes in storage RH, while crystallization rates from HPMCAS-containing dispersions were not. PVP and HPMCAS were similar in terms of their ability to inhibit crystallization at low RH, but when the storage RH was increased to 75% or above, felodipine crystallization from PVP-containing solid dispersions proceeded much faster. It is hypothesized that this trend was caused by moisture-induced drug-polymer immiscibility in PVP-felodipine system. For PVP-containing solid dispersion samples stored at 75% RH and above, crystallization of the model drug felodipine seemed to approach a kinetic plateau, whereby a fraction of the drug still remained amorphous even after storage for 500 days or more. The physical stability of solid dispersions as a function of RH is highly dependent on the polymer used to form the solid dispersion, with PVP-containing dispersions being much less physically stable at high RH than HPMCAS-containing dispersions.

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.

Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis.

PubMed

Chatterjee, Paramita; Chakraborty, Arup; Mukherjee, Alok K

2018-07-05

Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)-155 (4) nm and 69 (1)-123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)-21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (whewellite, weddellite or mixture of whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Single crystal X-ray structure of the artists' pigment zinc yellow

NASA Astrophysics Data System (ADS)

Simonsen, Kim Pilkjær; Christiansen, Marie Bitsch; Vinum, Morten Gotthold; Sanyova, Jana; Bendix, Jesper

2017-08-01

The artists' pigment zinc yellow is in general described as a complex potassium zinc chromate with the empirical formula 4ZnCrO4·K2O·3H2O. Even though the pigment has been in use since the second half of the 19th century also in large-scale industrial applications, the exact structure had hitherto been unknown. In this work, zinc yellow was synthesised by precipitation from an aqueous solution of zinc nitrate and potassium chromate under both neutral and basic conditions, and the products were compared with the pigment used in industrial paints. Analyses by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and powder X-ray diffraction (PXRD), showed that the synthesised products and the industrial pigment were identical. Single-crystal X-ray crystallography determined the structure of zinc yellow as KZn2(CrO4)2(H2O)(OH) or as KZn2(CrO4)2(H3O2) emphasizing the μ-H3O2- moiety. Notably, the zinc yellow is isostructural to the recently structurally characterized cadmium analog and both belong to the natrochalcite structure type.

Silica nanoparticles produced by DC arc plasma from a solid raw materials

NASA Astrophysics Data System (ADS)

Kosmachev, P. V.; Vlasov, V. A.; Skripnikova, N. K.

2017-05-01

Plasma synthesis of SiO2 nanoparticles in experimental atmospheric pressure plasma reactor on the basis of DC arc plasma generator was presented in this paper. Solid high-silica raw materials such as diatomite from Kamyshlovskoye deposit in Russia, quartzite from Chupinskoye deposit in Russia and milled window glass were used. The obtained nanoparticles were characterized based on their morphology, chemical composition and size distribution. Scanning electron microscopy, laser diffractometry, nitrogen absorption (Brunauer-Emmett-Teller method), X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy were used to characterize the synthesized products. The obtained silica nanoparticles are agglomerated, have spherical shape and primary diameters between 10-300 nm. All samples of synthesized nanopowders were compared with commercial nanopowders.

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.

Characterization of ALD grown TixAlyN and TixAlyC thin films

NASA Astrophysics Data System (ADS)

Kinnunen, S. A.; Malm, J.; Arstila, K.; Lahtinen, M.; Sajavaara, T.

2017-09-01

Atomic layer deposition (ALD) was used to grow TixAlyN and TixAlyC thin films using trimethylaluminum (TMA), titanium tetrachloride and ammonia as precursors. Deposition temperature was varied between 325 °C and 500 °C. Films were also annealed in vacuum and N2-atmosphere at 600-1000 °C. Wide range of characterization methods was used including time-of-flight elastic recoil detection analysis (ToF-ERDA), X-ray diffractometry (XRD), X-ray reflectometry (XRR), Raman spectroscopy, ellipsometry, helium ion microscopy (HIM), atomic force microscopy (AFM) and 4-point probe measurement for resistivity. Deposited films were roughly 100 nm thick and contained mainly desired elements. Carbon, chlorine and hydrogen were found to be the main impurities.

Characterization of the modified nickel-zinc ferrite nanoparticles coated with APTES by salinization reaction

NASA Astrophysics Data System (ADS)

Zainal, Israa G.; Al-Shammari, Ahmed Majeed; Kachi, Wjeah

2018-05-01

Surface functionalization of magnetic iron oxide nanoparticles (NPs) is a kind of functional materials, which have been widely used in the biotechnology and catalysis. In this study, Nickel-Zinc ferrite nanoparticles was functionalized with amino propyl triethoxy silane (APTES) by silanization reaction and both non coated and organosilane-coated magnetite characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometry, Fourier transformed infrared spectroscopy (FTIR) and atomic force microscopy. Basic groups of amino anchored on the external surface of the coated magnetite were observed. Our study procedure nanoparticles which have surface with free - NH2 groups which can carry out ionic interaction with carboxylic groups and act as a carrier of biological molecules, drugs and metals.

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.

A novel energy transfer inducing strong enhancement of electric dipole transition in Na3Mo12PO40:xEu3+ phosphors

NASA Astrophysics Data System (ADS)

Long, Jinqiao; Wang, Tianman; Luo, Zhirong; Gao, Yong; Song, Baoling; Liang, Jing; Liao, Sen; Huang, Yingheng; Zhang, Huaxin

2017-08-01

A series of Na3Mo12PO40:xEu3+ phosphors have been successfully synthesized by a solid-state method, and characterized by powder x-ray diffraction (PXRD). The PXRD results confirm that the samples have crystal phases of Na3Mo12PO40. For PL spectra of Na3Mo12PO40:2.0Eu3+ excited by 394 and 465 nm, R (R is the peak area ratio of 5D0  →  7F2 to 5D0  →  7F1) is only 1.46 with an excitation of 394 nm, but increases to 3.03 with an excitation of 465 nm. Furthermore, a new enhancement of electric dipole transition is observed. Emission spectrum (PL) intensity at 617 nm excited by 465 nm is 1.95 times as high as the excitation spectrum (PLE) intensity at 465 nm. Thus, cooperative energy transfers from the magnetic dipole (MD) Eu3+ center to the electric dipole (ED) Eu3+ center when excited by 465 nm is demonstrated for the new fluorescent behavior.

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.

Investigation on structural and electrical properties of Fe doped ZnO nanoparticles synthesized by solution combustion method

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

Ram, Mast, E-mail: mastram1999@yahoo.com; Bala, Kanchan; Sharma, Hakikat

In the present study, nanoparticles of Fe doped zinc oxide (ZnO) [Zn{sub 1-x}Fe{sub x}O where x=0.0, 0.01, 0.02, 0.03 and 0.05] were prepared by cost effective solution combustion method. The powder X-ray diffractometry confirms the formation of single phase wurtzite structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the micrsostructure of Fe-doped ZnO nanoparticles. The DC electrical conductivity was found to increase with temperature and measurement was carried out in the temperature range of 300-473K. DC electrical conductivity increases with temperature and decreases with Fe doping concentration.

Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles.

PubMed

Pidchenko, Ivan; Kvashnina, Kristina O; Yokosawa, Tadahiro; Finck, Nicolas; Bahl, Sebastian; Schild, Dieter; Polly, Robert; Bohnert, Elke; Rossberg, André; Göttlicher, Jörg; Dardenne, Kathy; Rothe, Jörg; Schäfer, Thorsten; Geckeis, Horst; Vitova, Tonya

2017-02-21

Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M 4 high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U(IV), U(V), and U(VI) existing simultaneously in the same sample. The contributions of the three different uranium redox states are quantified with the iterative transformation factor analysis (ITFA) method. U L 3 XAS and transmission electron microscopy (TEM) reveal that initially sorbed U(VI) species recrystallize to nonstoichiometric UO 2+x nanoparticles within 147 days when stored under anoxic conditions. These U(IV) species oxidize again when exposed to air. U M 4 HR-XANES data demonstrate strong contribution of U(V) at day 10 and that U(V) remains stable over 142 days under ambient conditions as shown for magnetite nanoparticles containing 1000 ppm U. U L 3 XAS indicates that this U(V) species is protected from oxidation likely incorporated into octahedral magnetite sites. XAS results are supported by density functional theory (DFT) calculations. Further characterization of the samples include powder X-ray diffraction (pXRD), scanning electron microscopy (SEM) and Fe 2p X-ray photoelectron spectroscopy (XPS).

A porous Cd(II) metal-organic framework with high adsorption selectivity for CO2 over CH4

NASA Astrophysics Data System (ADS)

Zhu, Chunlan

2017-05-01

Metal-organic frameworks (MOFs) have attracted a lot of attention in recent decades. We applied a semi-rigid four-carboxylic acid linker to assemble with Cd(II) ions to generate a novel microporous Cd(II) MOF material. Single crystal X-ray diffraction study reveals the different two dimension (2D) layers can be further packed together with an AB fashion by hydrogen bonds (O4sbnd H4⋯O7 = 1.863 Å) to construct a three dimension (3D) supermolecular architecture. The resulting sample can be synthesized under solvothermal reactions successfully, which exhibits high selectivity adsorption of CO2 over CH4 at room temperature. In addition, the obtained sample was characterized by thermal gravimetric analyses (TGA), Fourier-transform infrared spectra (FT-IR), elemental analysis (CHN) and powder X-ray diffraction (PXRD).

Synthesis of nano-sized crystalline oxide ion conducting fluorite-type Y 2O 3-doped CeO 2 using perovskite-like BaCe 0.9Y 0.1O 2.95 (BCY) and study of CO 2 capture properties of BCY

NASA Astrophysics Data System (ADS)

Sneha, B. R.; Thangadurai, V.

2007-10-01

Formation of nano-sized Y 2O 3-doped CeO 2 (YCO) was observed in the chemical reaction between proton conducting Y 2O 3-doped BaCeO 3 (BCY) and CO 2 in the temperature range 700-1000 °C, which is generally prepared by wet-chemical methods that include sol-gel, hydrothermal, polymerization, combustion, and precipitation reactions. BCY can capture CO 2 of 0.13 g per ceramic gram at 700 °C, which is comparable to that of the well-known Li 2ZrO 3 (0.15 g per ceramic gram at 600 °C). Powder X-ray diffraction (PXRD), energy dispersive X-ray analysis (EDX), laser particle size analysis (LPSA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ac impedance spectroscopy were employed to characterize the reaction product obtained from reaction between BCY and CO 2 and subsequent acid washing. PXRD study reveals presence of fluorite-like CeO 2 ( a=5.410 (1) Å) structure and BaCO 3 in reaction products. TEM investigation of the acid washed product showed the formation of nano-sized material with particle sizes of about 50 nm. The electrical conductivity of acid washed product (YCO) in air was found to be about an order higher than the undoped CeO 2 reported in the literature.

Uptake Mechanisms of Eu(III) on Hydroxyapatite: A Potential Permeable Reactive Barrier Backfill Material for Trapping Trivalent Minor Actinides.

PubMed

Xu, Lin; Zheng, Tao; Yang, Shitong; Zhang, Linjuan; Wang, Jianqiang; Liu, Wei; Chen, Lanhua; Diwu, Juan; Chai, Zhifang; Wang, Shuao

2016-04-05

The permeable reactive barrier (PRB) technique has attracted an increasing level of attention for the in situ remediation of contaminated groundwater. In this study, the macroscopic uptake behaviors and microscopic speciation of Eu(III) on hydroxyapatite (HAP) were investigated by a combination of theoretical modeling, batch experiments, powder X-ray diffraction (PXRD) fitting, and X-ray absorption spectroscopy (XAS). The underlying removal mechanisms were identified to further assess the application potential of HAP as an effective PRB backfill material. The macroscopic analysis revealed that nearly all dissolved Eu(III) in solution was removed at pH 6.5 within an extremely short reaction time of 5 min. In addition, the thermodynamic calculations, desorption experiments, and PXRD and XAS analyses definitely confirmed the formation of the EuPO4·H2O(s) phase during the process of uptake of dissolved Eu(III) by HAP via the dissolution-precipitation mechanism. A detailed comparison of the present experimental findings and related HAP-metal systems suggests that the relative contribution of precipitation to the total Eu(III) removal increases as the P:Eu ratio decreases. The dosage of HAP-based PRB for the remediation of groundwater polluted by Eu(III) and analogous trivalent actinides [e.g., Am(III) and Cm(III)] should be strictly controlled depending on the dissolved Eu(III) concentration to obtain an optimal P:M (M represents Eu, Am, or Cm) ratio and treatment efficiency.

Kinetics of intercalation of fluorescent probes in magnesium–aluminium layered double hydroxide within a multiscale reaction–diffusion framework

PubMed Central

Saliba, Daniel

2016-01-01

We report the synthesis of magnesium–aluminium layered double hydroxide (LDH) using a reaction–diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium–aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’. PMID:27698034

Kinetics of intercalation of fluorescent probes in magnesium-aluminium layered double hydroxide within a multiscale reaction-diffusion framework

NASA Astrophysics Data System (ADS)

Saliba, Daniel; Al-Ghoul, Mazen

2016-11-01

We report the synthesis of magnesium-aluminium layered double hydroxide (LDH) using a reaction-diffusion framework (RDF) that exploits the multiscale coupling of molecular diffusion with chemical reactions, nucleation and growth of crystals. In an RDF, the hydroxide anions are allowed to diffuse into an organic gel matrix containing the salt mixture needed for the precipitation of the LDH. The chemical structure and composition of the synthesized magnesium-aluminium LDHs are determined using powder X-ray diffraction (PXRD), thermo-gravimetric analysis, differential scanning calorimetry, solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared and energy dispersive X-ray spectroscopy. This novel technique also allows the investigation of the mechanism of intercalation of some fluorescent probes, such as the neutral three-dimensional rhodamine B (RhB) and the negatively charged two-dimensional 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), using in situ steady-state fluorescence spectroscopy. The incorporation of these organic dyes inside the interlayer region of the LDH is confirmed via fluorescence microscopy, solid-state lifetime, SSNMR and PXRD. The activation energies of intercalation of the corresponding molecules (RhB and HPTS) are computed and exhibit dependence on the geometry of the involved probe (two or three dimensions), the charge of the fluorescent molecule (anionic, cationic or neutral) and the cationic ratio of the corresponding LDH. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

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

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.

Microporous Cd(II) metal-organic framework as fluorescent sensor for nitroaromatic explosives at the sub-ppm level

NASA Astrophysics Data System (ADS)

Wang, Xing-Po; Han, Lu-Lu; Wang, Zhi; Guo, Ling-Yu; Sun, Di

2016-03-01

A novel Cd(II) metal-organic framework (MOF) based on a rigid biphenyltetracarboxylic acid, [Cd4(bptc)2(DMA)4(H2O)2·4DMA] (1) was successfully synthesized under the solvothermal condition and characterized by single-crystal X-ray diffraction and further consolidated by elemental analyses, powder X-ray diffraction (PXRD), infrared spectra (IR) and luminescent measurements. Single crystal X-ray diffraction analysis reveals that compound 1 is 4-connected PtS (Point symbol: {42·84}) network based on [Cd2(COO)4] secondary building units (SBUs). Its inherent porous and emissive characteristics make them to be a suitable fluorescent probe to sense small solvents and nitroaromatic explosives. Compound 1 shows obviously solvent-dependent emissive behaviors, especially for acetone with very high fluorescence quenching effect. Moreover, compound 1 displays excellent sensing of nitroaromatic explosives at sub-ppm level, giving a detection limit of 0.43 ppm and 0.37 ppm for nitrobenzene (NB) and p-nitrotoluene (PNT), respectively. This shows this Cd(II) MOF can be used as fluorescence probe for the detection of nitroaromatic explosives.

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.

Crystal structure of cobalt hydroxide carbonate Co2CO3(OH)2: density functional theory and X-ray diffraction investigation.

PubMed

González-López, Jorge; Cockcroft, Jeremy K; Fernández-González, Ángeles; Jimenez, Amalia; Grau-Crespo, Ricardo

2017-10-01

The cobalt carbonate hydroxide Co 2 CO 3 (OH) 2 is a technologically important solid which is used as a precursor for the synthesis of cobalt oxides in a wide range of applications. It also has relevance as a potential immobilizer of the toxic element cobalt in the natural environment, but its detailed crystal structure is so far unknown. The structure of Co 2 CO 3 (OH) 2 has now been investigated using density functional theory (DFT) simulations and powder X-ray diffraction (PXRD) measurements on samples synthesized via deposition from aqueous solution. Two possible monoclinic phases are considered, with closely related but symmetrically different crystal structures, based on those of the minerals malachite [Cu 2 CO 3 (OH) 2 ] and rosasite [Cu 1.5 Zn 0.5 CO 3 (OH) 2 ], as well as an orthorhombic phase that can be seen as a common parent structure for the two monoclinic phases, and a triclinic phase with the structure of the mineral kolwezite [Cu 1.34 Co 0.66 CO 3 (OH) 2 ]. The DFT simulations predict that the rosasite-like and malachite-like phases are two different local minima of the potential energy landscape for Co 2 CO 3 (OH) 2 and are practically degenerate in energy, while the orthorhombic and triclinic structures are unstable and experience barrierless transformations to the malachite phase upon relaxation. The best fit to the PXRD data is obtained using a rosasite model [monoclinic with space group P112 1 /n and cell parameters a = 3.1408 (4) Å, b = 12.2914 (17) Å, c = 9.3311 (16) Å and γ = 82.299 (16)°]. However, some features of the PXRD pattern are still not well accounted for by this refinement and the residual parameters are relatively poor. The relationship between the rosasite and malachite phases of Co 2 CO 3 (OH) 2 is discussed and it is shown that they can be seen as polytypes. Based on the similar calculated stabilities of these two polytypes, it is speculated that some level of stacking disorder could account for the poor fit of the PXRD data. The possibility that Co 2 CO 3 (OH) 2 could crystallize, under different growth conditions, as either rosasite or malachite, or even as a stacking-disordered phase intermediate between the two, requires further investigation.

Quinoline derivative containing monomeric and polymeric metal carboxylates: Synthesis, crystal structure and gas adsorption study over a 2D layered framework

NASA Astrophysics Data System (ADS)

Gayen, Saikat; Saha, Debraj; Koner, Subratanath

2018-06-01

A new supramolecular metal-carboxylate framework [Co(mqc)2]n (1), and another monomeric compound [Zn (mqc)2(H2O)] (2) (mqcH = 4-methoxy 2-quinolinecarboxylic acid) have been synthesized solvothermally and characterized by single crystal X-ray diffraction, elemental analysis, IR spectra, UV-vis spectra, powdered X-ray diffraction (PXRD) and thermogravimetric analysis. Compound 1 is a 2D coordination polymer, extended to a 3D porous supramolecular network having void space in between 2D layers. Compound 1 exhibits gas uptake capacity of N2, H2, CO2 and CH4 like small gas molecules in which moderately high uptake of H2 and CO2 takes place among the 2D MOFs. While the Zn variety, compound 2 features a one-dimensional chain like structure through strong intermolecular hydrogen-bonding.

Crystal structure, spectrum character and explosive property of a new cocrystal CL-20/DNT

NASA Astrophysics Data System (ADS)

Liu, Ke; Zhang, Gao; Luan, Jieyu; Chen, Zhiqun; Su, Pengfei; Shu, Yuanjie

2016-04-01

A new cocrystal explosive of 2,4,6,8,10,12-hexanitrohexaazaiso-wurtzitane(CL-20) and 2,5-dinitrotoluene(DNT) in a molar ratio of 1:2 has been prepared by slow solvent evaporation method. Crystal structure of the cocrystal characterized by single crystal X-ray diffraction (SXRD) reveals that the cocrystal is formed by intermolecular hydrogen bond interactions and belongs to the triclinic system with P-1 group. Moreover, the obivious differences of powder X-ray diffraction (PXRD) patterns, infrared spectroscopy and Raman spectroscopy confirm that the intermolecular interactions have great influence for the crystal structure and formation of cocrystal. The cocrystal exhibits a lower impact height of 44 cm, suggesting a substantial reduction of sensitivity in comparison with CL-20. And thermal test results showed cocrystal obtains a lower melting point than DNT, which means huge advantages in blasting engineering.

Syntheses, structure characterization and dissolution of two novel cocrystals of febuxostat

NASA Astrophysics Data System (ADS)

Kang, Yanlei; Gu, Jianming; Hu, Xiurong

2017-02-01

Febuxostat was investigated due to its significant effect in the treatment of gout. However, its poor water solubility hinder its potential applications. In recent years, cocrystals have increasingly being applied to enhance the drug solubility. To improve the solubility, two cocrystals of Febuxostat were synthesized through the method of cooling crystallization. The prepared cocrystals febuxostat-isonicotinamide(FEB-INA) and febuxostat-arginine(FEB-Arg) were studied by microscopical observation, Powder X-Ray Diffraction(PXRD), Single Crystal X-ray Diffraction, Differential Scanning Calorimetry(DSC), and infrared spectrometry. At the same time, the cocrystals' solubility and dissolution rate were explored. Both the cocrystals showed higher solubility compared to the pure drug. The FEB-Arg cocrystal enhanced about 900 times of solubility compared to the pure drug. The current study proved that cocrystallization can be a better way to enhance the solubility of the poorly water-soluble drug.

Structural, mechanical, electrical and optical properties of a new lithium boro phthalate NLO crystal synthesized by a slow evaporation method

NASA Astrophysics Data System (ADS)

Mohanraj, K.; Balasubramanian, D.; Jhansi, N.

2017-11-01

A new non-linear optical (NLO) single crystal of lithium boro phthalate (LiBP) was grown by slow solvent evaporation technique. The powder sample was subjected to powder X-ray diffraction (PXRD) to find its crystalline nature and the crystal structure of the grown crystal was determined using single crystal X-ray (SXRD) diffraction analysis. The Fourier Transform Infrared (FTIR) spectrum was recorded for grown crystal to identify the various functional groups present in the compound. The mechanical property of the LiBP single crystal was studied using Vickers microhardness tester. The dielectric constant and dielectric loss measurements were carried out for the grown crystal at various temperatures. The grown crystal was subjected to UV-Visible Spectral Studies to analyze the linear optical behavior of the grown crystal. The Kurtz-Perry Powder technique was employed to measure the Second Harmonic Generation efficiency of the grown crystal.

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.

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.

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.

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).

Carbon Coated α-Fe2O3 Photoanode Synthesized by a Facile Anodic Electrodeposition for Highly Efficient Water Oxidation

NASA Astrophysics Data System (ADS)

Zhang, Honglei; Li, Longzhu; Liu, Changhai; Wang, Wenchang; Liang, Penghua; Mitsuzak, Naotoshi; Chen, Zhidong

2018-05-01

This work provides a facile anodic electrodeposition method for synthesizing carbon coated α-Fe2O3 photoanode followed by annealing treatment with argon atmosphere. Compared with bare hematite photoanode, the carbon coated α-Fe2O3 photoanodes annealed at lower temperature (Fe2O3/C-L) and higher temperature (Fe2O3/C-H) have higher photocurrent density as 0.3 and 0.5 mA cm-2 (at 1.23 V vs. RHE), respectively. The excellent PEC performance is attributed to the synergistic reaction of carbon and vacancy oxygen. The morphology and properties of the sample were characterized with scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, UV-Vis spectra, X-ray diffractometry, X-ray photoelectron spectra, and photoelectrical measurements.

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.

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.

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.

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.

Synthesis and characterization of a series of nickel( ii ) alkoxide precursors and their utility for Ni(0) nanoparticle production

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

Treadwell, LaRico J.; Boyle, Timothy J.; Phelan, W. Adam

2017-02-22

We synthesized a series of nickel(II) aryloxide ([Ni(OAr) 2(py) x]) precursors from an amide-alcohol exchange using [Ni(NR 2) 2] in the presence of pyridine (py). The H-OAr selected were the mono- and di-ortho-substituted 2-alkyl phenols: alkyl = methyl (H-oMP), iso-propyl (H-oPP), tert-butyl (H-oBP) and 2,6-di-alkyl phenols (alkyl = di-iso-propyl (H-DIP), di-tert-butyl (H-DBP), di-phenyl (H-DPhP)). Furthermore, the crystalline products were solved as solvated monomers and structurally characterized as [Ni(OAr) 2(py) x], where x = 4: OAr = oMP (1), oPP (2); x = 3: OAr = oBP (3), DIP (4); x = 2: OAr = DBP (5), DPhP (6). The excitedmore » states (singlet or triplet) and various geometries of 1–6 were identified by experimental UV-vis and verified by computational modeling. Magnetic susceptibility of the representative compound 4 was fit to a Curie Weiss model that yielded a magnetic moment of 4.38(3)μ B consistent with a Ni 2+ center. Compounds 1 and 6 were selected for decomposition studied under solution precipitation routes since they represent the two extremes of coordination. The particle size and crystalline structure were characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). Finally, the materials isolated from 1 and 6 were found by TEM to form irregular shape nanomaterials (8–15 nm), which by PXRD were found to be Ni 0 hcp (PDF: 01-089-7129) and fcc (PDF: 01-070-0989), respectively.« less

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

Sonochemical synthesis and structural characterization of a new nanostructured Co(II) supramolecular coordination polymer with Lewis base sites as a new catalyst for Knoevenagel condensation.

PubMed

Joharian, Monika; Abedi, Sedigheh; Morsali, Ali

2017-11-01

A new Co(II) mixed-ligand coordination supramolecular polymer with composition [Co 2 (ppda)(4-bpdh) 2 (NO 3 ) 2 ] n (1) (where, ppda=p-phenylenediacrylic acid, 4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) was synthesized using solvothermal, mechanochemical and sonochemical methods. Compound 1 and the new nanostructure have been characterized by single-crystal X-ray, infrared spectroscopy (IR), powder X-ray diffraction (PXRD) analysis and scanning electron microscopy (SEM). The thermal stability of compound 1 was also studied by thermal gravimetric analysis (TGA). The surface area of these compounds was determined by BET. The single-crystal X-ray data shows a new interesting two-dimensional coordination polymer (CP). In addition, the effect of various sonication concentrations of initial reagents, power of ultrasound irradiation and also the time on the size and morphology of nano-structured coordination polymer 1 were evaluated. Moreover, it has been demonstrated that the nanostructure of the CP1 can be used as a catalyst in Knoevenagel condensation reaction. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and Characterization of Cabamazepine Cocrystal in Polymer Solution.

PubMed

Zhang, Hao; Zhu, Ying; Qiao, Ning; Chen, Yang; Gao, Linghuan

2017-12-01

In this study, we attempted to prepare carbamazepine (CBZ) cocrystal through the solution method in ethanol-water solvent mixture (volume ratio 1:1) and polyvinyl pyrrolidone (PVP) solution. Nicotinamide (NIC) and saccharin (SAC) were selected as cocrystal coformers. Cocrystal screening products were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Powder X-ray Diffraction (PXRD) techniques. Characterization results show that in ethanol-water solvent mixture, pure CBZ-NIC cocrystal can be prepared, while CBZ-SAC cocrystal cannot be obtained. The addition of PVP can inhibit CBZ-NIC cocrystal formation and facilitate CBZ-SAC cocrystal formation.

Preparation and Characterization of Carbamazepine Cocrystal in Polymer Solution

PubMed Central

Zhang, Hao; Zhu, Ying; Chen, Yang; Gao, Linghuan

2017-01-01

In this study, we attempted to prepare carbamazepine (CBZ) cocrystal through the solution method in ethanol-water solvent mixture (volume ratio 1:1) and polyvinyl pyrrolidone (PVP) solution. Nicotinamide (NIC) and saccharin (SAC) were selected as cocrystal coformers. Cocrystal screening products were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and Powder X-ray Diffraction (PXRD) techniques. Characterization results show that in ethanol-water solvent mixture, pure CBZ-NIC cocrystal can be prepared, while CBZ-SAC cocrystal cannot be obtained. The addition of PVP can inhibit CBZ-NIC cocrystal formation and facilitate CBZ-SAC cocrystal formation. PMID:29194387

Characterization of dehydration and hydration behavior of calcium lactate pentahydrate and its anhydrate.

PubMed

Sakata, Yukoh; Shiraishi, Sumihiro; Otsuka, Makoto

2005-12-20

The use of calcium lactate pentahydrate (CLP) as an additional filler-binder for direct compaction of tablets has been reported to result in a short disintegration time and rapid drug release. The aim of this study was to understand the dehydration and hydration behavior of CLP and calcium lactate anhydrate (CLA) under various conditions of storage temperature and relative humidity. The removal and acquisition of crystal water were investigated by using differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The PXRD results indicated that CLP exists as a crystalline solid and CLA as an amorphous solid. Dehydration of CLP resulted in aggregated particles of CLA with an increase in average particle size. The dehydration and hydration kinetics of CLP were analyzed with the Hancock-Sharp equation on the basis of the isothermal DSC data. The dehydration of CLP followed a zero-order mechanism (Polany-Winger equation). In contrast, the surface roughness of CLA was significantly decreased by hydration. The hydration of CLA followed a three-dimensional diffusion model (Ginstling-Brounshtein equation).

Synthesis, characterization and solid-state properties of [Zn(Hdmmthiol)2]\\cdot2H2O complex

NASA Astrophysics Data System (ADS)

Dagdelen, Fethi; Aydogdu, Yildirim; Dey, Kamalendu; Biswas, Susobhan

2016-05-01

The zinc(II) complex with tridentate thiohydrazone ligand have been prepared by metal template reaction. The metal template reaction was used to prepare the zinc (II) complex with tridentate thiohydrazone ligand. The reaction of diacetylmonoxime and, morpholine N-thiohydrazidewith Zn(OAc)2 \\cdot2H2O under reflux yielded the formation of the [Zn(Hdmmthiol )2]\\cdot2H2O complex. The complex was characterized by a combination of protocols including elemental analysis, UV+vis, FT-IR, TG and PXRD. The temperature dependence of the electrical conductivity and the optical property of the [Zn(Hdmmthiol )2] \\cdot2H2O complex is called H2dammthiol was studied. Powder X-ray diffraction (PXRD) method was used to investigate the crystal structure of the sample. The zinc complex was shown to be a member of the triclinic system. The zinc complex was determined to have n-type conductivity as demonstrated in the hot probe measurements. The complex was determined to display direct optical transition with band gaps of 2.52eV as determined by the optical absorption analysis.

[Analysis and characterization of Belamcanda chinensis with space mutagenesis breeding by X-ray fluorescence analysis and X-ray diffraction].

PubMed

Guan, Ying; Ding, Xi-Feng; Wang, Wen-Jing; Guo, Xi-Hua; Zhu, Yan-Ying

2008-02-01

The contents of various elements in the fourth generation Belamcanda chinensis (L.) DC. with space mutagenesis breeding were analyzed and characterized. X-ray fluorescence spectrum analysis (XRF) and powder X-ray diffraction (PXRD) were applied jointly. It was found that the content of K element in the space flight mutagenesis increases 1.03 and 0.31 times, Mg enhances 1.44 and 0.06 times, but Al reduces 38.5% and 85.5% respectively compared to the contents in the ground group and the comparison group, while those of Ca, Mn and Fe enhance 0.95, 0.30 and 0.29 times respectively contrasted to the ground group. Besides, there was discovered the crystal of whewellite in the Belamcanda chinensis (L.) DC. and the content in the ground group is less than that of the outer space and the outer space group, which in turn is less than that of the comparison group. It is concluded that the contents of mineral elements indispensable to body in the space group are closer or superior to the comparison, group as compared to the ground group. In the present paper, a quick and simple appraising method is offered, which may be of great significance to the popularization of the planting outer space Chinese traditional medicine to filtrate more excellent breed and set up norm of quality appraisal.

Cationic surfactant assisted ultrasound synthesis of Dy3+ doped CdSiO3 nanostructures for white LED application

NASA Astrophysics Data System (ADS)

Basavaraj, R. B.; Nagabhushana, H.; Lingaraju, K.; Prasad, B. Daruka

2017-05-01

In this paper we report for the first time Dy3+ (1-7 mol %) doped CdSiO3 nanophosphors prepared via facile ultrasound supported sonochemical route using EGCG (epigallocatechin gallate). The final product was well characterized by PXRD, FTIR, SEM, TEM and PL. The powder X-ray diffraction (PXRD) profiles showed monoclinic phase with highly crystalline nature. The sonication time, concentration of the surfactant play vital role in tuning the morphology. The crystallite size was calculated from PXRD patterns as well as by TEM image and it was found to 20-30 nm. The Fourier transform infrared spectroscopy (FTIR) results confirmed the presence of Si-O-Si and Si-O stretching vibrations in CdSiO3. Photoluminescence properties of Dy3+ (1-7 mol %) doped CdSiO3 excited under near ultra violet wavelength (350 nm) was studied in order to investigate the possibility of its use in white light emitting diode applications. The emission spectra consists of intra 4f transitions of Dy3+, namely 4F9/2 → 6H15/2 (480 nm), and 4F9/2 → 6H13/2 (574 nm) respectively. The 3 mol% Dy3+ doped phosphor showed maximum intensity. The Commission Internationale de I'Eclairage (CIE) and correlated color temperature (CCT) was evaluated. Further, the quantum efficiency and color purity results of the product showed high efficiency and it was highly useful in white light emitting diodes (wLEDs) applications.

M(II)-dipyridylamide-based coordination frameworks (M=Mn, Co, Ni): Structural transformation

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

Tzeng, Biing-Chiau; Selvam, TamilSelvi; Tsai, Miao-Hsin

2016-11-15

A series of 1-D double-zigzag (([M(papx){sub 2}(H{sub 2}O){sub 2}](ClO{sub 4}){sub 2}){sub n}; M=Mn, x=s (1), x=o (3); M=Co, x=s (4), x=o (5); M=Ni, x=s (6), x=o (7)) and 2-D polyrotaxane ([Mn(paps){sub 2}(ClO{sub 4}){sub 2}]{sub n} (2)) frameworks were synthesized by reactions of M(ClO{sub 4}){sub 2} (M=Mn, Co, and Ni) with papx (paps, N,N’-bis(pyridylcarbonyl)-4,4’-diaminodiphenylthioether; papo, N,N’-bis(pyridylcarbonyl)-4,4’-diaminodiphenyl ether), which have been isolated and structurally characterized by X-ray diffraction. Based on powder X-ray diffraction (PXRD) experiments, heating the double-zigzag frameworks underwent structural transformation to give the respective polyrotaxane ones. Moreover, grinding the solid samples of the respective polyrotaxanes in the presence of moisturemore » also resulted in the total conversion to the original double-zigzag frameworks. In this study, we have successfully extended studies to Mn{sup II}, Co{sup II}, and Ni{sup II} frameworks from the previous Zn{sup II}, Cd{sup II}, and Cu{sup II} ones, and interestingly such structural transformation is able to be proven experimentally by powder and single-crystal X-ray diffraction studies as well. - Graphical abstract: 1-D double-zigzag and 2-D polyrotaxane frameworks of M(II)-papx (x=s, o; M=Mn, Co, Ni) frameworks can be interconverted by heating and grinding in the presence of moiture, and such structural transformation has be proven experimentally by powder and single-crystal X-ray diffraction studies.« less

Preparation, electronic structure, and chemical bonding of lead-free (1 - x)(K0.5Bi0.5)TiO3- xBaTiO3 solid solution

NASA Astrophysics Data System (ADS)

Sasikumar, S.; Saravanan, R.; Saravanakumar, S.; Robert, M. Charles

2018-01-01

Polycrystalline lead-free (1 - x)(K0.5Bi0.5)TiO3- xBaTiO3, ((1 - x)KBT- xBT) ( x = 0.00, 0.08, 0.12) ceramics were synthesized via solid-state reaction method. The powder X-ray diffraction (PXRD) and structural refinement results confirm that a single-phase tetragonal structure with space group P4mm. Charge density distribution inside the unit cell of (1 - x)KBT- xBT was investigated by the maximum entropy method. Charge density analysis reveals the reduction in ionic nature along K/Bi-O bond and enhancement of covalent nature along Ti-O bond with the addition of BaTiO3. The charge density distribution studies done using maximum entropy method for (1 - x)KBT- xBT have not been done so far. The surface morphology study was done using scanning electron microscopy (SEM). Energy dispersive X-rays spectra (EDS) were used to investigate the elemental compositions present in the system. The dielectric constant and loss tangent were studied as a function of frequency. The dielectric constant and loss were decreased with increase of frequency. Room temperature dielectric constant ( ɛ) and loss (tan δ) were measured for x = 0.00 about 511 and 0.51, respectively, at a frequency of 10 kHz.

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.

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

Petrova, V. A.; Orekhov, A. S.; Chernyakov, D. D.

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.

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.

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.

Hydrothermal epitaxy and resultant properties of EuTiO3 films on SrTiO3(001) substrate

PubMed Central

2014-01-01

We report a novel epitaxial growth of EuTiO3 films on SrTiO3(001) substrate by hydrothermal method. The morphological, structural, chemical, and magnetic properties of these epitaxial EuTiO3 films were examined by scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffractometry, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometry, respectively. As-grown EuTiO3 films with a perovskite structure were found to show an out-of-plane lattice shrinkage and room-temperature ferromagnetism, possibly resulting from an existence of Eu3+. Postannealing at 1,000°C could reduce the amount of Eu3+, relax the out-of-plane lattice shrinkage, and impact the magnetic properties of the films. PACS 81.10.Aj; 81.15.-z; 61.05.-a PMID:24948889

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

NASA Astrophysics Data System (ADS)

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-01

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO4·KOH·H2O or more accurately as KCd2(CrO4)2(H3O2) illustrating the μ-H3O2- species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V).

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

PubMed

Christiansen, Marie Bitsch; Sørensen, Mikkel Agerbæk; Sanyova, Jana; Bendix, Jesper; Simonsen, Kim Pilkjær

2017-03-15

In an investigation of the artists' materials used by P. S. Krøyer the contents of the tube colours found in Krøyer's painting cabinet were examined. In most cases, the results of the pigment analyses were as expected based on our knowledge of artists' colours used in the late 1800s and early 1900s. However, in one of the tube colours labelled "Jaune de Cadmium Citron" (cadmium lemon yellow) an extremely rare cadmium chromate pigment was found. The pigment was analysed and characterised by Raman microscopy (MRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (PXRD), single-crystal X-ray crystallography, and electron paramagnetic resonance (EPR) spectroscopy. Cadmium chromate was synthesised by precipitation from an aqueous solution of cadmium nitrate and potassium chromate, and the resulting yellow crystals proved identical to the pigment found in the tube colour "Jaune de Cadmium Citron". The structure determined by single-crystal X-ray diffraction identified the pigment as 2CdCrO 4 ·KOH·H 2 O or more accurately as KCd 2 (CrO 4 ) 2 (H 3 O 2 ) illustrating the μ-H 3 O 2 - species. The yellow colour of the paint sample taken from the tube had a greenish hue, which became even more prominent upon storage and drying. EPR analysis of the sample showed the presence of paramagnetic degradation products containing Cr(III) and Cr(V). Copyright © 2016 Elsevier B.V. All rights reserved.

First quadruple-glycine bridging mono-lanthanide-substituted borotungstate hybrids.

PubMed

Liu, Jiancai; Yu, Jing; Han, Qing; Wen, Yue; Chen, Lijuan; Zhao, Junwei

2016-10-18

A class of novel organic-inorganic hybrid lanthanide (Ln)-substituted Keggin-type borotungstates K 4 Na 4 H 4 [Ln 2 (gly) 4 (α-BW 11 O 39 ) 2 ]·23H 2 O [Ln = Ce 3+ (1), Pr 3+ (2), Nd 3+ (3), Sm 3+ (4), Eu 3+ (5), Tm 3+ (6); gly = glycine] have been synthesized from the reaction of K 8 [BW 11 O 39 H]·13H 2 O, NaAc·6H 2 O and Ln(NO 3 ) 3 ·6H 2 O by employing gly ligands as structure-stabilizing agents in the conventional aqueous solution system and structurally characterized by elemental analyses, IR spectroscopy, thermogravimetric (TG) analyses, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The common prominent structural feature of isomorphic 1-6 is that all of them consist of two mono-Ln-substituted Keggin [Ln(α-BW 11 O 39 )] 6- fragments linked by four gly ligands, furnishing an intriguing dimeric assembly of the quadruple-gly-connective mono-Ln-substituted borotungstate, in which each carboxylic oxygen atom from gly ligands is bound to Ln 3+ cations in the μ 2 -O or μ 3 -O mode. To the best of our knowledge, 1-6 represent the first examples of inorganic-organic hybrid Ln-substituted borotungstates functionalized by quadruple amino acid bridges. The solid-state photoluminescence properties of 3-5 have been determined at ambient temperature and the photoluminescence emission spectra exhibit the characteristic emission bands derived from Ln 3+ centers. The thermostability of 1-6 has been studied and the thermal decomposition procedure of 3 has been comprehensively investigated with the assistance of variable-temperature PXRD patterns and variable-temperature IR spectra. Furthermore, magnetic susceptibility measurements of 1, 2 and 4 have been conducted.

Sonochemical synthesis of a multi-responsive regenerable water-stable zinc(II) fluorescent probe for highly selective, sensitive and real-time sensing of benzaldehyde, ferric ion and PH.

PubMed

Wang, Xin Rui; Wang, Xing Ze; Li, Yong; Liu, Kun; Liu, Shi Xin; Du, Jing; Huang, Zhuo; Luo, Yan; Huo, Jian Zhong; Wu, Xiang Xia; Liu, Yuan Yuan; Ding, Bin

2018-06-01

In this work, a novel water-stable coordination polymer with {4 4 } network topology {[Zn(L) 2 (NO 3 ) 2 ]} n (1) (L = 4,4'-Bis(triazol-1-ylmethyl)biphenyl) has been synthesized through the hydrothermal and sonochemical approaches. 1 has been characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy, UV-vis absorption spectrum and scanning electron microscopy (SEM). PXRD patterns of the as-synthesized samples 1 have confirmed the purity of the bulky samples. In the sonochemical preparation approaches, different ultrasound irradiation power and ultrasound time were also used in order to investigate the impact factor for morphology and size of nano-structured 1. Photo-luminescence studies have revealed that 1 can efficiently distinguish Fe 3+ from Fe 2+ and other metal ions. On the other hand, 1 also can exhibit a highly sensitive, excellently selective and real-time detection of benzaldehyde and pH through photo-luminescence quenching process. As for 1, density functional theory (DFT) and time-dependent DFT (TDDFT) theory has been applied to calculate these spectroscopic data, the result agree with the experimental results for detection of benzaldehyde. Photo-luminescent recyclability results indicated 1 can be reused at least five times in the detection process. To the best of our knowledge, this is the first example of a multi-responsive regenerable luminescent sensor for highly selective, sensitive and real-time sensing of Fe 3+ over Fe 2+ , benzaldehyde and pH values. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

N-donor co-ligands driven two new Co(II)- coordination polymers with bi- and trinuclear units: Crystal structures, and magnetic properties

NASA Astrophysics Data System (ADS)

Zhou, Zhi-Hang; Han, Min-Le; Wu, Ya-Pan; Dong, Wen-Wen; Li, Dong-Sheng; Lu, Jack Y.

2016-10-01

Two new Co(II) coordination polymers(CPs), namely [Co2(bpe)2(Hbppc)]n (1) and [Co3(μ3-OH)(bppc)(bpm)(H2O)]·3H2O (2) (H5bppc=biphenyl-2,4,6,3‧,5‧-pentacarboxylic acid, bpe=1,2-bis(4-pyridyl)ethene, bpm=bis(4-pyridyl)amine), have been obtained and characterized by elemental analysis, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), IR spectra and thermogravimetric analysis (TGA). 1 shows a binodal (4,6)-connected fsc net with a (44·610·8)(44·62) topology, while 2 shows a binodal (5,7)-connected 3D network based on trinuclear [Co3(μ3-OH)]5+ units with unusual (3.46.52.6)(32.46.57.65.7) topology. Variable-temperature magnetic susceptibility measurements reveals that complex 1 shows ferromagnetic interactions between the adjacent Co(II) ions, whereas 2 is a antiferromagnetic system.

Design and synthesis of two luminescent Zn(II)-based coordination polymers with different structures regulated by different solvent system

NASA Astrophysics Data System (ADS)

Wu, Wei-Ping; Wen, Gui-Lin; Liao, Yi; Wang, Jun; Lu, Lu; Wu, Yu; Xie, Bin

2016-08-01

Two new coordination polymers (CPs) [Zn(HL)(H2O)]n (1) and [Zn3(L)2(H2O)2]n·(H2O)n (2), based on a multifunctional ligand combined carboxylate groups and a nitrogen donor group 5-(6-carboxypyridin-2-yl)isophthalic acid (H3L), have been synthesized under different solvent media and fully characterized by powder X-ray diffraction (PXRD), infrared (IR) spectra, elemental analyses (EA) and thermogravimetric analyses (TGA). Single-crystal X-ray diffraction analysis reveals that 1 shows 1D dimeric chain structure, while 2 gives a 3D dense packing framework. Topology analysis illustrates that 2 can be simplified as a 3-nodal net (4, 5, 6-connected net) with the point symbol of {44·62}{46·64}2{48·66·8}. In addition, solid state luminescent properties of two complexes have also been studied in detail, which may act as the potential optical materials.

Synthesis, structural, spectroscopic and optical studies of charge transfer complex salts.

PubMed

Manikandan, Maruthappan; Mahalingam, Thaiyan; Hayakawa, Yasuhiro; Ravi, Ganesan

2013-01-15

New charge transfer molecular complex adducts of picric acid (C6H3N3O7) with triethylamine (C6H15N) and dimethylformamide (HCON(CH3)2) were synthesized successfully for the first time. Chemical composition and stoichiometry of the synthesized complex salts were verified by CHN elemental analysis. Solubility of the complex salts have been determined by gravimetric method and single crystals of two new salts were grown by low temperature solution growth technique. Crystal system, crystalline nature and cell parameters of the grown crystals were determined by single crystal X-ray diffraction (SXRD) and powder X-ray diffraction (PXRD) analyses. The formations of the charge-transfer complex, functional groups and the modes of vibrations have been confirmed by Fourier transform infrared (FTIR) spectroscopy. In order to know the linear and nonlinear optical suitability for device fabrication, UV-Vis (UV) spectral analysis and relative second harmonic generation (SHG) efficiency test were performed for the grown crystals. Copyright © 2012 Elsevier B.V. All rights reserved.

Sulfaguanidine cocrystals: Synthesis, structural characterization and their antibacterial and hemolytic analysis.

PubMed

Abidi, Syed Sibte Asghar; Azim, Yasser; Khan, Shahper Nazeer; Khan, Asad U

2018-02-05

Sulfaguanidine (SG), belongs to the class of sulfonamide drug used as an effective antibiotic. In the present work, using crystal engineering approach two novel cocrystals of SG were synthesized (SG-TBA and SG-PT) with thiobarbutaric acid (TBA) and 1,10-phenanthroline (PT), characterized by solid state techniques viz., powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and the crystal structures were determined by single crystal X-ray diffraction studies. A comparative antibacterial activity and hemolytic potential was done on SG drug, coformers and their cocrystals. The tested cocrystals formulations showed almost two fold higher antibacterial activity against the tested strains of bacteria Gram-positive bacteria (S. mutans and E. faecalis) and Gram-negative bacteria (E. coli, K. pneumonia and E. clocae) over SG alone and their coformers. Cocrystal SG-TBA showed better antibacterial activity and reduced hemolysis, thereby, reduced cytotoxicity than SG-PT. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis, structural, spectroscopic and optical studies of charge transfer complex salts

NASA Astrophysics Data System (ADS)

Manikandan, Maruthappan; Mahalingam, Thaiyan; Hayakawa, Yasuhiro; Ravi, Ganesan

2013-01-01

New charge transfer molecular complex adducts of picric acid (C6H3N3O7) with triethylamine (C6H15N) and dimethylformamide (HCON(CH3)2) were synthesized successfully for the first time. Chemical composition and stoichiometry of the synthesized complex salts were verified by CHN elemental analysis. Solubility of the complex salts have been determined by gravimetric method and single crystals of two new salts were grown by low temperature solution growth technique. Crystal system, crystalline nature and cell parameters of the grown crystals were determined by single crystal X-ray diffraction (SXRD) and powder X-ray diffraction (PXRD) analyses. The formations of the charge-transfer complex, functional groups and the modes of vibrations have been confirmed by Fourier transform infrared (FTIR) spectroscopy. In order to know the linear and nonlinear optical suitability for device fabrication, UV-Vis (UV) spectral analysis and relative second harmonic generation (SHG) efficiency test were performed for the grown crystals.

Synthesis and spectral studies on Cd(II) dithiocarbamate complexes and their use as precursors for CdS nanoparticles

NASA Astrophysics Data System (ADS)

Sathiyaraj, Ethiraj; Padmavathy, Krishnaraj; Kumar, Chandran Udhaya; Krishnan, Kannan Gokula; Ramalingan, Chennan

2017-11-01

Bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (1) and (2,2‧-bipyridine) bis(N-cyclopropyl-N-4-chlorobenzyldithiocarbamato-S,S‧)cadmium(II) (2) have been synthesized and characterized by FT-IR, 1HNMR and 13C NMR analyses. For the complex 2, single crystal X-ray diffraction analysis and computational studies (optimized geometry, HOMO-LUMO and MEP) have been executed employing DFT/B3LYP method with LANL 2DZ basic set. The optimized bond lengths and bond angles agree well with the experimental results. The complexes 1 and 2 have been used as single source precursors for the synthesis of ethyleneglycol capped CdS1 and CdS2 nanoparticles, respectively. CdS1 and CdS2 nanoparticles have been synthesized by solvothermal method. PXRD, SEM, Elemental colour mapping, EDAX, TEM and UV-Vis spectroscopy have been used to characterize the as-prepared CdS nanoparticles. The X-ray diffraction pattern confirms both their hexagonal structures.

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

Coriandrum sativum mediated synthesis of silver nanoparticles and evaluation of their biological characteristics

NASA Astrophysics Data System (ADS)

Senthilkumar, N.; Aravindhan, V.; Ruckmani, K.; Vetha Potheher, I.

2018-05-01

Silver (Ag) nanoparticles (NPs) were prepared by percolated green synthesis method using Coriandrum sativum leaf, root, seed and stem extracts and reported its antibacterial activity. The synthesized Ag NPs were confirmed by UV–visible Spectroscopy, Powder x-ray Diffraction (PXRD), Fourier Transform Infra Red (FT-IR) Spectroscopy analyzes. The Maximum absorbance observed around 400–450 nm reveal the characteristic absorbance of Ag NPs. The Dynamic Light Scattering (DLS) analysis shows the stability of synthesized NPs with average size varying from 35 to 53 nm and also zeta potential stability varying from ‑20 to ‑30 mV. The cubic structure, crystalline nature and purity of the material was confirmed by powder x-ray diffraction studies. FT-IR spectrum shows the presence of various functional groups in the resultant material. The Field Emission Scanning Electron Microscopy (FESEM) image shows the surface morphology of the synthesized NPs and the Energy Dispersive x-ray Analysis (EDAX) confirms the presence of silver metal ions. The Coriandrum sativum aqueous extract exhibited excellent antimicrobial activity against Klebsiella pneumoniae (Gram -ve) bacteria. Numerous studies have been made previously in our field of study but optimization has not been carried out by both extract (different parts like leaf, root, seed and stem) and without addition of any external source such as chemicals, heat etc.

Ultra-small plutonium oxide nanocrystals: an innovative material in plutonium science.

PubMed

Hudry, Damien; Apostolidis, Christos; Walter, Olaf; Janssen, Arne; Manara, Dario; Griveau, Jean-Christophe; Colineau, Eric; Vitova, Tonya; Prüssmann, Tim; Wang, Di; Kübel, Christian; Meyer, Daniel

2014-08-11

Apart from its technological importance, plutonium (Pu) is also one of the most intriguing elements because of its non-conventional physical properties and fascinating chemistry. Those fundamental aspects are particularly interesting when dealing with the challenging study of plutonium-based nanomaterials. Here we show that ultra-small (3.2±0.9 nm) and highly crystalline plutonium oxide (PuO2 ) nanocrystals (NCs) can be synthesized by the thermal decomposition of plutonyl nitrate ([PuO2 (NO3 )2 ]⋅3 H2 O) in a highly coordinating organic medium. This is the first example reporting on the preparation of significant quantities (several tens of milligrams) of PuO2 NCs, in a controllable and reproducible manner. The structure and magnetic properties of PuO2 NCs have been characterized by a wide variety of techniques (powder X-ray diffraction (PXRD), X-ray absorption fine structure (XAFS), X-ray absorption near edge structure (XANES), TEM, IR, Raman, UV/Vis spectroscopies, and superconducting quantum interference device (SQUID) magnetometry). The current PuO2 NCs constitute an innovative material for the study of challenging problems as diverse as the transport behavior of plutonium in the environment or size and shape effects on the physics of transuranium elements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Nonlinear refraction properties of nickel oxide thin films at 800 nm

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

Melo, Ronaldo P. Jr. de; Silva, Blenio J. P. da; Santos, Francisco Eroni P. dos

2009-11-01

Measurements of the nonlinear refractive index, n{sub 2}, of nickel oxide films prepared by controlled oxidation of nickel films deposited on substrates of soda-lime glass are reported. The structure and morphology of the samples were characterized by scanning electron microscopy, atomic force microscopy, and x-ray diffractometry. Samples of excellent optical quality were prepared. The nonlinear measurements were performed using the thermally managed eclipse Z-scan technique at 800 nm. A large value of n{sub 2}approx =10{sup -12} cm{sup 2}/W and negligible nonlinear absorption were obtained.

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).

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

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.

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.

Application of carrier and plasticizer to improve the dissolution and bioavailability of poorly water-soluble baicalein by hot melt extrusion.

PubMed

Zhang, Yilan; Luo, Rui; Chen, Yi; Ke, Xue; Hu, Danrong; Han, Miaomiao

2014-06-01

The objective of this study was to develop a suitable formulation for baicalein (a poorly water-soluble drug exhibiting high melting point) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts. The characteristic of solid dispersions prepared by HME was evaluated. The dissolution performance of the extrudates was compared to the pure drug and the physical mixtures. Physicochemical properties of the extrudates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Relative bioavailability after oral administration in beagle dogs was assessed. As a result, Kollidon VA64 and Eudragit EPO were selected as two carriers; Cremophor RH was used as the plasticizer. The dissolution of all the extrudates was significantly improved. DSC and PXRD results suggested that baicalein in the extrudates was amorphous. FTIR spectroscopy revealed the interaction between drug and polymers. After oral administration, the relative bioavailability of solid dispersions with VA64 and EPO was comparative, about 2.4- and 2.9-fold greater compared to the pure drug, respectively.

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

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

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.

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.

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.

Magnetic force microscopy study of domain walls in Co{sub 2}Z ferrite

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

Qin, Lang; Verweij, Henk, E-mail: verweij.1@osu.edu

2014-03-01

Graphical abstract: - Highlights: • Hexaferrite Co{sub 2}Z is synthesized through the modified Pechini method. • Magnetic domains are observed in anisotropic Co{sub 2}Z single grain using MFM. • Observed single grain domain thickness is in good agreement with Dotsh model. - Abstract: Hexaferrite Co{sub 2}Z was synthesized through the modified Pechini method. Partially oriented samples were obtained after consolidation with uniaxial pressing and calcination/sintering at 1300 °C/1330 °C. The sample composition and morphology was identified with X-ray diffractometry (XRD) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometry (EDS). MFM studies of the single grains revealed a domain structuremore » with 0.7 μm wide. The Co{sub 2}Z static magnetization was measured with a vibrating sample magnetometer (VSM), and was used to calculate a single grain domain with a thickness of 4.8 μm. This result is in good agreement with SEM observations of the single grain thickness.« less

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.

Purification Procedures for Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Gorelik, Olga P.; Nikolaev, Pavel; Arepalli, Sivaram

2001-01-01

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SWNT) material. The material is characterized at each step of the purification procedures by using different techniques including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), nuclear magnetic resonance (NMR), and high-performance liquid chromatography (HPLC). The identified impurities are amorphous and graphitic carbon, catalyst particle aggregates, fullerenes, and hydrocarbons. Solvent extraction and low-temperature annealing are used to reduce the amount of volatile hydrocarbons and dissolve fullerenes. Metal catalysts and amorphous as well as graphitic carbon are oxidized by reflux in acids including HCl, HNO3 and HF and other oxidizers such as H2O2. High-temperature annealing in vacuum and in inert atmosphere helps to improve the quality of SWNTs by increasing crystallinity and reducing intercalation.

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.

Fracture resistance of dental nickel-titanium rotary instruments with novel surface treatment: Thin film metallic glass coating.

PubMed

Chi, Chih-Wen; Deng, Yu-Lun; Lee, Jyh-Wei; Lin, Chun-Pin

2017-05-01

Dental nickel-titanium (NiTi) rotary instruments are widely used in endodontic therapy because they are efficient with a higher success rate. However, an unpredictable fracture of instruments may happen due to the surface characteristics of imperfection (or irregularity). This study assessed whether a novel surface treatment could increase fatigue fracture resistance of dental NiTi rotary instruments. A 200- or 500-nm thick Ti-zirconium-boron (Ti-Zr-B) thin film metallic glass was deposited on ProTaper Universal F2 files using a physical vapor deposition process. The characteristics of coating were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. In cyclic fatigue tests, the files were performed in a simulated root canal (radius=5 mm, angulation=60°) under a rotating speed of 300rpm. The fatigue fractured cross sections of the files were analyzed with their fractographic performances through scanning electron microscopy images. The amorphous structure of the Ti-Zr-B coating was confirmed by transmission electron microscopy and X-ray diffractometry. The surface of treated files presented smooth morphologies without grinding irregularity. For the 200- and 500-nm surface treatment groups, the coated files exhibited higher resistance of cyclic fatigue than untreated files. In fractographic analysis, treated files showed significantly larger crack-initiation zone; however, no significant differences in the areas of fatigue propagation and catastrophic fracture were found compared to untreated files. The novel surface treatment of Ti-Zr-B thin film metallic glass on dental NiTi rotary files can effectively improve the fatigue fracture resistance by offering a smooth coated surface with amorphous microstructure. Copyright © 2016. Published by Elsevier B.V.

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.

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.

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound.

PubMed

Pais, Joana M; Barroca, Maria João; Marques, Maria Paula M; Almeida Paz, Filipe A; Braga, Susana S

2017-01-01

Fisetin is a natural antioxidant with a wide range of nutraceutical properties, including antidiabetic, neuroprotecting, and suppression or prevention of tumors. The present work describes the preparation of a water-soluble, solid inclusion compound of fisetin with gamma-cyclodextrin (γ-CD), a cyclic oligosaccharide approved for human consumption. A detailed physicochemical analysis of the product is carried out using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13 C{ 1 H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host-guest units. The antioxidant activity of the γ-CD·fisetin inclusion compound is evaluated by the DPPH assay.

Synthesis of highly nanoporous YBO3 architecture via a co-precipitation approach and tunable luminescent properties.

PubMed

Liu, Lili; Zhang, Xianwen; Chaudhuri, Jharna

2015-01-01

We present a simple co-precipitation method to prepare highly nanoporous YBO(3) architecture using NaBO(3) ·  4H(2)O as a boric source and 600°C as the annealing temperature. The reaction was carried out under an aqueous condition without any organic solvent, surfactant, or catalysts. The prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photoluminescence of doped-nanoporous YBO(3):Eu(3+) was further investigated. It is expected that highly nanoporous YBO(3) architecture can be an ideal candidate for applications in catalysis, adsorption, and optoelectronic devices. © Wiley Periodicals, Inc.

Synthesis of metal-fluoride nanoparticles supported on thermally reduced graphite oxide.

PubMed

Schmitz, Alexa; Schütte, Kai; Ilievski, Vesko; Barthel, Juri; Burk, Laura; Mülhaupt, Rolf; Yue, Junpei; Smarsly, Bernd; Janiak, Christoph

2017-01-01

Metal-fluoride nanoparticles, (MF x -NPs) with M = Fe, Co, Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO) were obtained by microwave-assisted thermal decomposition of transition-metal amidinates, (M{MeC[N(iPr)] 2 } n ) or [M(AMD) n ] with M = Fe(II), Co(II), Pr(III), and tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium, Eu(dpm) 3 , in the presence of TRGO in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]). The crystalline phases of the metal fluorides synthesized in [BMIm][BF 4 ] were identified by powder X-ray diffraction (PXRD) to be MF 2 for M = Fe, Co and MF 3 for M = Eu, Pr. The diameters and size distributions of MF x @TRGO were from (6 ± 2) to (102 ± 41) nm. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were used for further characterization of the MF x -NPs. Electrochemical investigations of the FeF 2 -NPs@TRGO as cathode material for lithium-ion batteries were evaluated by galvanostatic charge/discharge profiles. The results indicate that the FeF 2 -NPs@TRGO as cathode material can present a specific capacity of 500 mAh/g at a current density of 50 mA/g, including a significant interfacial charge storage contribution. The obtained nanomaterials show a good rate capacity as well (220 mAh/g and 130 mAh/g) at a current density of 200 and 500 mA/g, respectively.

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.

In situ hydrothermal syntheses, structures and photoluminescent properties of four novel metal-organic frameworks constructed by lanthanide (Ln=Ce(III), Pr(III), Eu(III)) and Cu(I) metals with flexible dicarboxylate acids and piperazine-based ligands

NASA Astrophysics Data System (ADS)

Ay, Burak; Karaca, Serkan; Yildiz, Emel; Lopez, Valerie; Nanao, Max H.; Zubieta, Jon

2016-01-01

Four novel metal-organic frameworks,[Cu2Cl2(pyrz)]n (1) and (H2pip)n[Ln2(pydc)4(H2O)2]n (Ln=Ce (2), Pr (3) and Eu (4), H2pzdc=2,3-pyrazinedicarboxylic acid, pyrz=pyrazine, H2pydc=2,6-pyridinedicarboxylic acid, H2pip=piperazine) have been synthesized under hydrothermal conditions and characterized by the elemental analysis, ICP, Far IR (FIR), FT-IR spectra, TGA, single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). Compound 1 is two-dimensional containing Cl-Cu-Cl sites, while the lanthanide complexes contain one-dimensional infinite Ln-O-Ln chains. All the complexes show high thermal stability. The complexes 1-3 exhibit luminescence emission bands at 584, 598 and 614 nm at room temperature when excited at 300 nm. Complex 4 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature.

Non-Aqueous Sol-Gel Synthesis of FePt Nanoparticles in the Absence of In Situ Stabilizers

PubMed Central

Preller, Tobias; Knickmeier, Saskia; Porsiel, Julian Cedric; Temel, Bilal

2018-01-01

The synthesis of FePt nanocrystals is typically performed in an organic solvent at rather high temperatures, demanding the addition of the in situ stabilizers oleic acid and oleylamine to produce monomodal particles with well-defined morphologies. Replacing frequently-used solvents with organic media bearing functional moieties, the use of the stabilizers can be completely circumvented. In addition, various morphologies and sizes of the nanocrystals can be achieved by the choice of organic solvent. The kinetics of particle growth and the change in the magnetic behavior of the superparamagnetic FePt nanocrystals during the synthesis with a set of different solvents, as well as the resulting morphologies and stoichiometries of the nanoparticles were determined by powder X-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES)/mass spectrometry (ICP-MS), and superconducting quantum interference device (SQUID) measurements. Furthermore, annealing of the as-prepared FePt nanoparticles led to the ordered L10 phase and, thus, to hard magnetic materials with varying saturation magnetizations and magnetic coercivities. PMID:29751508

Synthesis, crystal structures, and optical properties of the π-π interacting pyrrolo[2,3-b]quinoxaline derivatives containing 2-thienyl substituent

NASA Astrophysics Data System (ADS)

Goszczycki, Piotr; Stadnicka, Katarzyna; Brela, Mateusz Z.; Grolik, Jarosław; Ostrowska, Katarzyna

2017-10-01

Three (E/Z)-diastereoisomers, based on pyrrolo[2,3-b]quinoxaline system as fluorophore and containing: 2-thienylmethyl (1), bis(2-thienylmethyl)-2-aminoethyl (3a), bis(2-thienylmethyl)-3-aminopropyl (3b) groups as substituents, were synthesized and characterized by X-ray structural analysis, PXRD, NMR, UV-Vis as well as fluorescence. These compounds are non-fluorescent in acetonitrile solution, however, they exhibit aggregation induced emission enhancement (AIEE) upon water addition and in solid state. X-ray structural analysis revealed that molecules with 2-thienylmethyl and bis(2-thienylmethyl)-2-aminoethyl groups form dimers and π-stacks through π-π interactions between anitiparallel oriented pyrroloquinoxaline cores with interplanar distances 3.45 Å and 3.20 Å, respectively. Conformation of bis(2-thienylmethyl)-3-aminopropyl group is imposed by incorporated DMSO-d6 solvent molecule and weak intermolecular S-π and CH-π interactions, that prevents π-π interaction between fluorophore cores. The correlation between crystal structure and fluorescent properties of synthesized molecules was discussed. The DFT calculations were performed to rationalize the differences between considered systems.

Hydrothermal synthesis, crystal structures, and enantioselective adsorption property of bis(L-histidinato)nickel(II) monohydrate

NASA Astrophysics Data System (ADS)

Ramos, Christian Paul L.; Conato, Marlon T.

2018-05-01

Despite the numerous researches in metal-organic frameworks (MOFs), there are only few reports on biologically important amino acids, histidine in particular, on its use as bridging ligand in the construction of open-framework architectures. In this work, hydrothermal synthesis was used to prepare a compound based on Ni2+ and histidine. The coordination assembly of imidazole side chain of histidine with divalent nickel ions in aqueous condition yielded purple prismatic solids. Single crystal X-ray diffraction (XRD) analysis of the product revealed structure for Ni(C6H8N3O2)2 • H2O that has a monoclinic (C2) structure with lattice parameters, a = 29.41, b = 8.27, c = 6.31 Å, β = 90.01 ˚. Circular dichroism - optical rotatory dispersion (CD-ORD), Powder X-ray diffraction (PXRD) and Fourier transform - infrared spectroscopy (FT-IR) analyses are conducted to further characterize the crystals. Enantioselective adsorption analysis using racemic mixture of 2-butanol confirmed bis(L-histidinato)nickel(II) monohydrate MOF crystal's enantioselective property preferentially favoring the adsorption of (S)-2-butanol isomer.

Ligand exchange synthesis of organometallic Rh nanoparticles and application in explosive sensing

NASA Astrophysics Data System (ADS)

Srivastav, Amit K.; Agrawal, Bhavesh; Swami, Bhavya; Agrawal, Yadvendra K.; Maity, Prasenjit

2017-06-01

Alkyne {phenyl acetylene (PA) and 9-ethynylphenanthrene (EPT)}-ligated Rh nanoparticles ( 1 and 2, respectively) with mean diameter of 1.5 ± 0.2 nm were synthesized via a facile and high-yield biphasic ligand exchange protocol using similar sized ethylene glycol (EG)-stabilized Rh nanoparticles as precursors (EG:Rh). The synthesized organometallic Rh nanoparticles were convincingly characterized using several spectroscopic and microscopic techniques, e.g., Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), optical absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). We propose that the syntheses mechanism relies on catalytic acetylenic (≡C-H, carbon-hydrogen) bond breaking by EG:Rh followed by strong metal-carbon bond formation with a vinyldiene (>C═C═M) motif. The obtained 1 and 2 showed luminescence property, which arises from ligand structure through intraparticle conjugation. Electron-rich phenanthrene-ligated Rh nanoparticles ( 2) showed good sensing performance for detection of electron deficient nitro-aromatic explosive molecules (NA) in solution phase through luminescence quenching method.

Facile Synthesis of Self-Assembled Flower-Like Mesoporous Zinc Oxide Nanoflakes for Energy Applications

NASA Astrophysics Data System (ADS)

Saranya, P. E.; Selladurai, S.

Flower-shaped self-assembled zinc oxide (ZnO) nanoflakes were successfully synthesized via a temperature-controlled hydrothermal method. The crystallinity and phase formation of the compound were determined from powder X-ray diffraction (PXRD) result. Surface morphology investigations reveal the self-assembled ZnO nanoflakes to form a spherical flower-like structure. In addition, the particle size was determined from high-resolution transmission electron microscope measurement as 18nm which is in accord with XRD and UV results. X-ray photo electron spectroscopy studies reveal the chemical composition and oxidation state of the ZnO nanoparticle. The specific surface area was calculated, and mesoporous nature was confirmed using Brunauer-Emmett-Teller analysis. Results support the superior interaction between the electrode and electrolyte ions through surface pores. Capacitive performance of the ZnO electrode material was determined using cyclic voltammetry and galvanostatic charge/discharge studies, and a maximum specific capacitance of 322F/g was obtained at 5mV/sec. Electrochemical impedance spectrum reveals the materials fast charge transfer kinetics.

Selective sensing of two novel coordination polymers based on tris(4-carboxylphenyl)phosphine oxide for organic molecules and Fe3+ and Hg2+ ions

NASA Astrophysics Data System (ADS)

Huo, Liangqin; Zhang, Jie; Gao, Lingling; Wang, Xiaoqing; Fan, Liming; Fang, Kegong; Hu, Tuoping

2017-12-01

Two novel coordination polymers, formulated as {[Zn(HTPO)(bib)]·4H2O}n (1), {[Cu3(TPO)2 (bib)3]·2DMF·0.5EtOH·0.5H2O}n (2) (H3TPO = tris(4-carboxylphenyl)phosphine oxide; bib = 1,4-bis(1H-imidazol-4-yl) benzene), have been synthesized under solvothermal method and characterized by single-crystal X-ray diffraction, elemental analysis (EA), IR spectra, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD). Structural analysis reveals that complex 1 is a 2D 4-connected sheet with an intriguing 2D + 2D→2D network. Complex 2 displays a 3D 3,4-connected net with the point symbol of {103}2{106}3. Furthermore, the photoluminescence properties of 1 and 2 were investigated in the solid state and various solvent emulsions, the results show that 1 and 2 have better fluorescent recognition for organic molecules, Fe3+ and Hg2+ ions.

Direct structural evidence of commensurate-to-incommensurate transition of hydrocarbon adsorption in a microporous metal organic framework

DOE PAGES

Banerjee, Debasis; Wang, Hao; Gong, Qihan; ...

2015-10-27

Here, the efficiency of physisorption-based separation of gas-mixtures depends on the selectivity of adsorbent which is directly linked to size, shape, polarizability and other physical properties of adsorbed molecules. Commensurate adsorption is an interesting and important adsorption phenomenon, where the adsorbed amount, location, and orientation of an adsorbate are commensurate with the crystal symmetry of the adsorbent. Understanding this phenomenon is important and beneficial as it can provide vital information about adsorbate–adsorbent interaction and adsorption–desorption mechanism. So far, only sporadic examples of commensurate adsorption have been reported in porous materials such as zeolites and metal organic frameworks (MOFs). In thismore » work we show for the first time direct structural evidence of commensurate-to-incommensurate transition of linear hydrocarbon molecules (C 2–C7) in a microporous MOF, by employing a number of analytical techniques including single crystal X-ray diffraction (SCXRD), in situ powder X-ray diffraction coupled with differential scanning calorimetry (PXRD-DSC), gas adsorption and molecular simulations.« less

Critical size of crystalline ZrO(2) nanoparticles synthesized in near- and supercritical water and supercritical isopropyl alcohol.

PubMed

Becker, Jacob; Hald, Peter; Bremholm, Martin; Pedersen, Jan S; Chevallier, Jacques; Iversen, Steen B; Iversen, Bo B

2008-05-01

Nanocrystalline ZrO(2) samples with narrow size distributions and mean particle sizes below 10 nm have been synthesized in a continuous flow reactor in near and supercritical water as well as supercritical isopropyl alcohol using a wide range of temperatures, pressures, concentrations and precursors. The samples were comprehensively characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS), and the influence of the synthesis parameters on the particle size, particle size distribution, shape, aggregation and crystallinity was studied. On the basis of the choice of synthesis parameters either monoclinic or tetragonal zirconia phases can be obtained. The results suggest a critical particle size of 5-6 nm for nanocrystalline monoclinic ZrO(2) under the present conditions, which is smaller than estimates reported in the literature. Thus, very small monoclinic ZrO(2) particles can be obtained using a continuous flow reactor. This is an important result with respect to improvement of the catalytic properties of nanocrystalline ZrO(2).

New supramolecular cocrystal of 2-amino-5-chloropyridine with 3-methylbenzoic acids: Syntheses, structural characterization, Hirshfeld surfaces and quantum chemical investigations

NASA Astrophysics Data System (ADS)

Thanigaimani, Kaliyaperumal; Khalib, Nuridayanti Che; Temel, Ersin; Arshad, Suhana; Razak, Ibrahim Abdul

2015-11-01

2-amino-5-chloropyridine: 3-methylbenzoic acid [(2A5CP) (3MBA)] (I) cocrystal was synthesized and its single crystal was grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The cocrystal belongs to the monoclinic crystallographic system with space group P21/c, Z = 4, and a = 13.3155 (5) Å, b = 5.5980 (2) Å, c = 18.3787 (7) Å, β = 110.045 (2)°. The crystal structure is stabilized by Npyridine-H•••Odbnd C, Cdbnd O-H•••Npyridine and C-H⋯O type hydrogen bonding interactions. The presence of unionized -COOH functional group in the cocrystal was identified both by spectral methods and X-ray structural analysis. The experimental studies obtained by using the methods of single crystal X-ray analysis, powder X-ray diffraction (PXRD) analysis, FTIR, 1H NMR and 13C NMR spectroscopies confirmed the predicted cocrystal. The supramolecular assembly of the cocrystal was analyzed and discussed. The molecular geometry, vibrational frequencies of the compound in the ground state were calculated by using the density functional theory (DFT) method with 6-311++G (d,p) basis set and were compared with the experimental data. Additionally, HOMO-LUMO energy gap, natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of the compound were performed at B3LYP/6-311++G (d,p) level. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.

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.

Nonlinear optical imaging for sensitive detection of crystals in bulk amorphous powders.

PubMed

Kestur, Umesh S; Wanapun, Duangporn; Toth, Scott J; Wegiel, Lindsay A; Simpson, Garth J; Taylor, Lynne S

2012-11-01

The primary aim of this study was to evaluate the utility of second-order nonlinear imaging of chiral crystals (SONICC) to quantify crystallinity in drug-polymer blends, including solid dispersions. Second harmonic generation (SHG) can potentially exhibit scaling with crystallinity between linear and quadratic depending on the nature of the source, and thus, it is important to determine the response of pharmaceutical powders. Physical mixtures containing different proportions of crystalline naproxen and hydroxyl propyl methyl cellulose acetate succinate (HPMCAS) were prepared by blending and a dispersion was produced by solvent evaporation. A custom-built SONICC instrument was used to characterize the SHG intensity as a function of the crystalline drug fraction in the various samples. Powder X-ray diffraction (PXRD) and Raman spectroscopy were used as complementary methods known to exhibit linear scaling. SONICC was able to detect crystalline drug even in the presence of 99.9 wt % HPMCAS in the binary mixtures. The calibration curve revealed a linear dynamic range with a R(2) value of 0.99 spanning the range from 0.1 to 100 wt % naproxen with a root mean square error of prediction of 2.7%. Using the calibration curve, the errors in the validation samples were in the range of 5%-10%. Analysis of a 75 wt % HPMCAS-naproxen solid dispersion with SONICC revealed the presence of crystallites at an earlier time point than could be detected with PXRD and Raman spectroscopy. In addition, results from the crystallization kinetics experiment using SONICC were in good agreement with Raman spectroscopy and PXRD. In conclusion, SONICC has been found to be a sensitive technique for detecting low levels (0.1% or lower) of crystallinity, even in the presence of large quantities of a polymer. Copyright © 2012 Wiley-Liss, Inc.

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

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.

Atomic Layer Deposition of Rhenium Disulfide.

PubMed

Hämäläinen, Jani; Mattinen, Miika; Mizohata, Kenichiro; Meinander, Kristoffer; Vehkamäki, Marko; Räisänen, Jyrki; Ritala, Mikko; Leskelä, Markku

2018-06-01

2D materials research is advancing rapidly as various new "beyond graphene" materials are fabricated, their properties studied, and materials tested in various applications. Rhenium disulfide is one of the 2D transition metal dichalcogenides that has recently shown to possess extraordinary properties such as that it is not limited by the strict monolayer thickness requirements. The unique inherent decoupling of monolayers in ReS 2 combined with a direct bandgap and highly anisotropic properties makes ReS 2 one of the most interesting 2D materials for a plethora of applications. Here, a highly controllable and precise atomic layer deposition (ALD) technique is applied to deposit ReS 2 thin films. Film growth is demonstrated on large area (5 cm × 5 cm) substrates at moderate deposition temperatures between 120 and 500 °C, and the films are extensively characterized using field emission scanning electron microscopy/energy-dispersive X-ray spectroscopy, X-ray diffractometry using grazing incidence, atomic force microscopy, focused ion beam/transmission electron microscopy, X-ray photoelectron spectroscopy, and time-of-flight elastic recoil detection analysis techniques. The developed ReS 2 ALD process highlights the potential of the material for applications beyond planar structure architectures. The ALD process also offers a route to an upgrade to an industrial scale. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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

Probing the local structure of crystalline NaBiO3·XH2O and its acidified derivatives

NASA Astrophysics Data System (ADS)

Kozma, Karoly; Surta, T. Wesley; Molina, Pedro I.; Lyubinetsky, Igor; Stoxen, Wynn; Byrne, Nicole M.; Dolgos, Michelle; Nyman, May

2018-07-01

Sodium bismuthate is a commercially available, inexpensive, non-toxic and very potent inorganic oxidant and photocatalyst. It is one of the important reagents for oxidative separation of Am3+ from the chemically similar lanthanide ions, for its recovery or safe disposal from reprocessed nuclear fuel. While the structure of NaBiO3 has been described from powder and neutron diffraction; the structure of NaBiO3·XH2O, the manufactured form of sodium bismuthate, is currently unknown. Herein, we describe the structure of NaBiO3·XH2O (X = 3) using pair distribution function (PDF) analysis of X-ray total scattering data. In our proposed structure model, NaBiO3·3H2O is similar to NaBiO3, but with turbostratic disorder in the stacking direction of the alternating Bi-O and Na-O layers. We propose locations for the lattice water, and its role in creating turbostratic disorder. We also used PDF to describe the structural evolution of sodium bismuthate upon exposure to nitric acid, the conditions employed in for nuclear fuel reprocessing. We supported the proposed model for pristine NaBiO3·3H2O and its acidified derivatives by a variety of techniques including thermogravimetry, powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). By employing both surface and bulk techniques, we hypothesize that the bismuth reduced to Bi3+ upon aqueous acid exposure remains in the lattice, rather than completely dissolving and/or depositing on the surface, as prior suggested. Using pretreated acidified sodium bismuthate samples, we delineated the effects of acid strength vs. bismuthate structure/composition on Ce3+ to Ce4+ oxidation efficacy.

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

Novel Nd 2WO 6-type Sm 2- xA xM 1- yB yO 6- δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) mixed conductors

NASA Astrophysics Data System (ADS)

Li, Qin; Thangadurai, Venkataraman

In the present work, we have explored novel Nd 2WO 6-type structure Sm 2- xA xM 1- yB yO 6- δ (A = Ca, Sr; M = Mo, W; B = Ce, Ni) as precursor for the development of solid oxide fuel cells (SOFCs) anodes. The formation of single-phase monoclinic structure was confirmed by powder X-ray diffraction (PXRD) for the A- and B-doped Sm 2MO 6 (SMO). Samples after AC measurements under wet H 2 up to 850 °C changed from Nd 2WO 6-type structure into Sm 2MoO 5 due to the reduction of Mo VI that was confirmed by PXRD and is consistent with literature. The electrical conductivity was determined using 2-probe AC impedance and DC method and was compared with 4-probe DC method. The total electrical conductivity obtained from these two different techniques was found to vary within the experimental error over the investigated temperature of 350-650 °C. Ionic and electronic conductivity were studied using electron-blocking electrodes technique. Among the samples studied, Sm 1.8Ca 0.2MoO 6- δ exhibits total conductivity of 0.12 S cm -1 at 550 °C in wet H 2 with an activation energy of 0.06 eV. Ca-doped SMO appears to be chemically stable against reaction with YSZ electrolyte at 800 °C for 24 h in wet H 2. The ionic transference number (t i) of Sm 1.9Ca 0.1MoO 6- δ in wet H 2 at 550 °C (pO 2 = 10 -25.5 atm) was found to be about 0.012 after subtraction of electrical lead resistance from the 2-probe AC data and showed predominate electronic conductors.

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.

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.

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.

Studies on Optical and Electrical Properties of Hafnium Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Jayaraman, Venkatachalam; Sagadevan, Suresh; Sudhakar, Rajesh

2017-07-01

In this paper, the synthesis and physico-chemical properties of hafnium oxide nanoparticles (HfO2 NPs) are analyzed and reported. The synthesis was carried out by the precipitation route by using hafnium tetrachloride (HfCl4) as precursor material with potassium hydroxide (KOH) dissolved in Millipore water. In the precipitation technique, the chemical reaction is comparatively simple, low-cost and non-toxic compared to other synthetic methods. The synthesized HfO2 NPs were characterized by using powder x-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Raman analysis, and high-resolution transmission electron microscopy (HRTEM). The monoclinic structure of the HfO2 NPs was resolved utilizing x-ray diffraction (XRD). The optical properties were studied from the UV-Vis absorption spectrum. The optical band gap of the HfO2NPs was observed to be 5.1 eV. The Raman spectrum shows the presence of HfO2 NPs. The HRTEM image showed that the HfO2 NPs were of spherical shape with an average particle size of around 28 nm. The energy-dispersive x-ray spectroscopy (EDS) spectrum obviously demonstrated the presence of HfO2 NPs. Analysis and studies on the dielectric properties of the HfO2 NPs such as the dielectric constant, the dielectric loss, and alternating current (AC) conductivity were carried out at varying frequencies and temperatures.

Crystal growth, differential gas adsorption, high thermal stability, and reversible coordination of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O)

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

Halake, Shobha; Ok, Kang Min, E-mail: kmok@cau.ac.kr

2015-11-15

Single crystals of two barium-organic framework materials, Ba(SBA)(DMF){sub 4} (CAUMOF-15) and Ba{sub 2}(BTEC)(H{sub 2}O) (CAUMOF-16), have been grown through solvothermal reactions (H{sub 2}SBA=4,4′-sulfonyldibenzoic acid and H{sub 4}BTEC=1,2,4,5-benzenetetracarboxylic acid). The crystal structures of the reported frameworks have been determined by single-crystal X-ray diffraction. The materials have been fully characterized by powder X-ray diffraction (PXRD), elemental analyses, Infrared (IR) spectroscopy, and thermogravimetric analyses (TGA). CAUMOF-15 reveals a three-dimensional open-framework that comprises of an inorganic motif with one-dimensional chains and the SBA linkers. CAUMOF-16 shows another three-dimensional backbone consisting of layers of edge-shared BaO{sub 9} and BaO{sub 10} polyhedra, and BTEC pillars. Bothmore » of the 3D frameworks exhibit relatively high thermal stabilities. The PXRD and IR spectral data confirm that CAUMOF-15 and CAUMOF-16 reveal reversible coordinations of the respective solvent molecules, DMF and H{sub 2}O. Gas adsorption properties towards nitrogen, hydrogen, and carbon dioxide have been also investigated. - Graphical abstract: Crystals of two new barium-organic frameworks, Ba(SBA)(DMF){sub 4} and Ba{sub 2}(BTEC)(H{sub 2}O), exhibiting a differential gas adsorption, a high thermal stability, and a reversible coordination of solvent molecules have been grown. - Highlights: • Crystals of two new 3D Ba-MOFs are grown. • The two Ba-MOFs reveal very high thermal stabilities up to ca. 400 °C. • Ba(SBA)(DMF){sub 4} exhibits differential gas adsorption properties. • The two Ba-MOFs show reversible coordination of the solvent molecules.« less

The Synthesis and Characterization of Gold-Core/LDH-Shell Nanoparticles

NASA Astrophysics Data System (ADS)

Rearick, Colton

In recent years, the field of nanomedicine has progressed at an astonishing rate, particularly with respect to applications in cancer treatment and molecular imaging. Although organic systems have been the frontrunners, inorganic systems have also begun to show promise, especially those based upon silica and magnetic nanoparticles (NPs). Many of these systems are being designed for simultaneous therapeutic and diagnostic capabilities, thus coining the term, theranostics. A unique class of inorganic systems that shows great promise as theranostics is that of layered double hydroxides (LDH). By synthesis of a core/shell structures, e.g. a gold nanoparticle (NP) core and LDH shell, the multifunctional theranostic may be developed without a drastic increase in the structural complexity. To demonstrate initial proof-of-concept of a potential (inorganic) theranostic platform, a Au-core/LDH-shell nanovector has been synthesized and characterized. The LDH shell was heterogeneously nucleated and grown on the surface of silica coated gold NPs via a coprecipitation method. Polyethylene glycol (PEG) was introduced in the initial synthesis steps to improve crystallinity and colloidal stability. Additionally, during synthesis, fluorescein isothiocyanate (FITC) was intercalated into the interlayer spacing of the LDH. In contrast to the PEG stabilization, a post synthesis citric acid treatment was used as a method to control the size and short-term stability. The heterogeneous core-shell system was characterized with scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), dynamic light scattering (DLS), and powder x-ray diffraction (PXRD). A preliminary in vitro study carried out with the assistance of Dr. Kaushal Rege's group at Arizona State University was to demonstrate the endocytosis capability of homogeneously-grown LDH NPs. The DLS measurements of the core-shell NPs indicated an average particle size of 212nm. The PXRD analysis showed that PEG greatly improved the crystallinity of the system while simultaneously preventing aggregation of the NPs. The preliminary in vitro fluorescence microscopy revealed a moderate uptake of homogeneous LDH NPs into the cells.

Crystal engineering of stable temozolomide cocrystals.

PubMed

Babu, N Jagadeesh; Sanphui, Palash; Nangia, Ashwini

2012-10-01

The antitumor prodrug temozolomide (TMZ) decomposes in aqueous medium of pH≥7 but is relatively stable under acidic conditions. Pure TMZ is obtained as a white powder but turns pink and then brown, which is indicative of chemical degradation. Pharmaceutical cocrystals of TMZ were engineered with safe coformers such as oxalic acid, succinic acid, salicylic acid, d,l-malic acid, and d,l-tartaric acid, to stabilize the drug as a cocrystal. All cocrystals were characterized by powder X-ray diffraction (PXRD), single crystal X-ray diffraction, and FT-IR as well as FT-Raman spectroscopy. Temozolomide cocrystals with organic acids (pK(a) 2-6) were found to be more stable than the reference drug under physiological conditions. The half-life (T(1/2)) of TMZ-oxalic and TMZ-salicylic acid measured by UV/Vis spectroscopy in pH 7 buffer is two times longer than that of TMZ (3.5 h and 3.6 h vs. 1.7 h); TMZ-succinic acid, TMZ-tartaric acid, and TMZ-malic acid also exhibited a longer half-life (2.3, 2.5, and 2.8 h, respectively). Stability studies at 40 °C and 75 % relative humidity (ICH conditions) showed that hydrolytic degradation of temozolomide in the solid state started after one week, as determined by PXRD, whereas its cocrystals with succinic acid and oxalic acid were intact at 28 weeks, thus confirming the greater stability of cocrystals compared to the reference drug. The intrinsic dissolution rate (IDR) profile of TMZ-oxalic acid and TMZ-succinic acid cocrystals in buffer of pH 7 is comparable to that of temozolomide. Among the temozolomide cocrystals examined, those with succinic acid and oxalic acid exhibited both an improved stability and a comparable dissolution rate to the reference drug. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Reflection and Transmission Coefficient of Yttrium Iron Garnet Filled Polyvinylidene Fluoride Composite Using Rectangular Waveguide at Microwave Frequencies

PubMed Central

Soleimani, Hassan; Abbas, Zulkifly; Yahya, Noorhana; Shameli, Kamyar; Soleimani, Hojjatollah; Shabanzadeh, Parvaneh

2012-01-01

The sol-gel method was carried out to synthesize nanosized Yttrium Iron Garnet (YIG). The nanomaterials with ferrite structure were heat-treated at different temperatures from 500 to 1000 °C. The phase identification, morphology and functional groups of the prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The YIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by a solution casting method. The magnitudes of reflection and transmission coefficients of PVDF/YIG containing 6, 10 and 13% YIG, respectively, were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequencies. The results indicate that the presence of YIG in polymer composites causes an increase in reflection coefficient and decrease in transmission coefficient of the polymer. PMID:22942718

Occurrence and structural characterization of gas hydrates associated with a cold vent field, offshore Vancouver Island

NASA Astrophysics Data System (ADS)

Lu, Hailong; Moudrakovski, Igor; Riedel, Michael; Spence, George; Dutrisac, Regent; Ripmeester, John; Wright, Fred; Dallimore, Scott

2005-10-01

Gas hydrate samples recovered from a cold vent field offshore Vancouver Island were studied in detail both by macroscopic observations and instrumental methods (powder X-ray diffraction method (PXRD), nuclear magnetic resonance (NMR), and Raman spectroscopy). It was found that gas hydrates were massive from 2.64 to 2.94 m below seafloor (mbsf), elongated, nodular and tabular from 4.60 to 4.81 mbsf, and vein-like from 5.48 to 5.68 mbsf, showing a trend of decreasing hydrate content with increasing depth. All samples were determined to be structure I hydrate from PXRD, NMR, and Raman spectroscopies. The hydration numbers were estimated to be 6.1 ± 0.2 on average as determined from the methane distribution over the cage sites from NMR and Raman analytical results. Estimates of conversion levels indicated that ˜78% of the water in the massive samples was hydrate, down to a low value of ˜0.4% for the pore hydrate samples. The results are compared with measurements on synthetic hydrates and samples recovered from below the permafrost on the Mallik site. Differences in methane content and lattice parameters for synthetic and natural samples are relatively minor. Additional work is needed to address the presence of minor gas components and the heterogeneity of natural hydrate samples.

In Vitro-In Vivo Relationship of Amorphous Insoluble API (Progesterone) in PLGA Microspheres.

PubMed

Pu, Chenguang; Wang, Qiao; Zhang, Hongjuan; Gou, Jingxin; Guo, Yuting; Tan, Xinyi; Xie, Bin; Yin, Na; He, Haibing; Zhang, Yu; Wang, Yanjiao; Yin, Tian; Tang, Xing

2017-12-01

The mechanism of PRG release from PLGA microspheres was studied and the correlation of in vitro and in vivo analyses was assessed. PRG-loaded microspheres were prepared by the emulsion-evaporate method. The physical state of PRG and microstructure changings during the drug release period were evaluated by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) respectively. Pharmacokinetic studies were performed in male Sprague-Dawley rats, and the in vivo-in vitro correlation (IVIVC) was established by linear fitting of the cumulative release (%) in vitro and fraction of absorption (%) in vivo. PXRD results indicated recrystallization of PRG during release. The changes of microstructure of PRG-loaded microspheres during the release period could be observed in SEM micrographs. Pharmacokinetics results performed low burst-release followed a steady-released manner. The IVIVC assessment exhibited a good correlation between vitro and in vivo. The burst release phase was caused by diffusion of amorphous PRG near the surface, while the second release stage was impacted by PRG-dissolution from crystal depots formed in microspheres. The IVIVC assessment suggests that the in vitro test method used in this study could predict the real situation in vivo and is helpful to study the release mechanism in vivo.

Synthesis, characterisation and anion exchange properties of copper, magnesium, zinc and nickel hydroxy nitrates

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

Biswick, Timothy; Jones, William; Pacula, Aleksandra

2006-01-15

Anion exchange reactions of four structurally related hydroxy salts, Cu{sub 2}(OH){sub 3}NO{sub 3}, Mg{sub 2}(OH){sub 3}NO{sub 3}, Ni{sub 2}(OH){sub 3}NO{sub 3} and Zn{sub 3}(OH){sub 4}(NO{sub 3}){sub 2} are compared and trends rationalised in terms of the strength of the covalent bond between the nitrate group and the matrix cation. Powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis are used to characterise the materials. Replacement of the nitrate anions in the zinc and copper salts with benzoate anions is possible although exchange of the zinc salt is accompanied by modification of the layer structure frommore » one where zinc is exclusively six-fold coordinated to a structure where there is both six- and four-fold zinc coordination. Magnesium and nickel hydroxy nitrates, on the other hand, hydrolyse to their respective metal hydroxides. -- Graphical abstract: PXRD patterns of exchange products of (a) Zn{sub 3}(OH){sub 4}(NO{sub 3}){sub 2} (b) Zn{sub 5}(OH){sub 8}(NO{sub 3}){sub 2}.2H{sub 2}O and (c) Cu{sub 2}(OH){sub 3}NO{sub 3} with benzoate anions.« less

Supramolecular assembly in the epiisopiloturine hydrochloride salt

NASA Astrophysics Data System (ADS)

Mafud, Ana Carolina; Reinheimer, Eric W.; Lima, Filipe Camargo Dalmatti Alves; Batista, Larissa Fernandes; de Paula, Karina; Véras, Leiz Maria Costa; de Souza de Almeida Leite, José Roberto; Venancio, Tiago; Mascarenhas, Yvonne Primerano

2017-05-01

Epiisopiloturine hydrochloride (Epi-HCl) salt was synthetized from epiisopiloturine, an in vivo anthelmintic compound against Schistosoma mansoni worms. Despite there being no acute toxicity in mammalian cells, the compound's water insolubility makes its administration difficult. In this communication, we report the characterization of Epi-HCl its features by spectroscopy, thermal analysis, and PXRD. The single crystals suitable to X-ray diffraction were grown by slow evaporation technique. To better understand the nature of Epi-HCl' solid state, SS-NMR was also used. The salt's intramolecular structure was maintained via cation-pi intramolecular interactions, which in conjunction with hydrogen bonding, gives rise to an extended supramolecular assembly. The interatomic distances within the cations and environment around the chloride anion vary as function of temperature, suggesting a packing relaxation.

Colloidal synthesis of monodispersed ZnS and CdS nanocrystals from novel zinc and cadmium complexes

NASA Astrophysics Data System (ADS)

Onwudiwe, Damian C.; Mohammed, Aliyu D.; Strydom, Christien A.; Young, Desmond A.; Jordaan, Anine

2014-06-01

Monodispersed spherical and hexagonal shaped ZnS and CdS nanocrystals respectively, have been synthesized using novel heteroleptic complexes of xanthate (S2CObu) and dithiocarbamate (S2CNMePh). The nanocrystals were prepared via colloidal route and stabilized in hexadecylamine (HDA). The morphology of the as-prepared nanocrystals was characterized using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and powdered X-ray diffraction (p-XRD) analysis. An average diameter of 7.2 nm and 8.6 nm were obtained for the ZnS and CdS respectively. The optical properties of the nanoparticles studied by UV-vis and photoluminescence (PL) spectroscopy showed a blue shift in the absorption spectra, and band edge emission respectively.

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.

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.

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

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.

MicroRaman, PXRD, EDS and microscopic investigation of magnesium calcite biomineral phases. The case of sea urchin biominerals

NASA Astrophysics Data System (ADS)

Borzęcka-Prokop, B.; Wesełucha-Birczyńska, A.; Koszowska, E.

2007-02-01

This study concerns Mg-calcite characterization (and in particular molecular structure and microstructural studies of mineral phases) of a sea urchin mineralised test and spines. Sea urchins are spiny sea animals (kingdom Animalia, phylum Echinodermata, class Echinoidea). Microscopic observations, SEM, EDS, PXRD and spectroscopic microRaman methods have been applied to characterize the biomineral parts of the sea urchin. The latter technique is very useful in research of biological systems and especially suitable for monitoring differences within biomineral phases exhibiting varieties of morphological forms. Crystalline magnesium calcium carbonate, Mg xCa 1- xCO 3 (magnesian calcite; space group R-3 cH; a = 4.9594(8) Å, c = 16.886(6) Å), has been identified as the predominant biomineral component.

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.

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.

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.

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

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.

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

Yin, Fei; Chen, Jing; Liang, Yongfeng

Two coordination polymers [Co(dnbab){sub 2}(bimb)](H{sub 2}O){sub 4} (1) and [Zn(dnbab){sub 2}(bimb)](H{sub 2}O){sub 5} (2) (Hdnbab=4-[(3,5-dinitrobenzoyl)amino]benzoic acid, bimb=1,4-bis(1-imidazolyl) benzene) have been solvothermally synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Complexes 1 and 2 are isostructures and each displays an one-dimensional (1D) zigzag chain, which further forms a 3D supramolecular architecture with 1-D channels via inter-chain π–π interactions and hydrogen bonds. Moreover, the magnetic properties of 1 and fluorescent properties of 2 have been investigated. - Graphical abstract: Two coordination supramolecular frameworks [Co(dnbab){sub 2}(bimb)](H{sub 2}O){sub 4}(1)more » and [Zn(dnbab){sub 2}(bimb)](H{sub 2}O){sub 5}(2) (Hdnbab=4-[(3,5-dinitrobenzoyl)amino]benzoic acid, bimb=1,4-bis(1-imidazolyl) benzene) have been synthesized and characterized by X-ray single-crystal diffraction. Their thermal, magnetic and fluorescent properties have also been studied. - Highlights: • Two isomorphic Co(II)/Zn(II) complexes with the mixed-ligands have been synthesized. • Hydrogen bonds and π–π stacking interactions directed the final 3-D architecture assembly. • Both Co(II) and Zn(II) complexes show good thermal stability. • Co complex exhibits antiferromagnetic interaction. • The fluorescent property of Zn(II) complex has been investigated in the solid state.« less

Study on four polymorphs of bifendate based on X-ray crystallography.

PubMed

Nie, Jinju; Yang, Dezhi; Hu, Kun; Lu, Yang

2016-05-01

Bifendate, a synthetic anti-hepatitis drug, exhibits polycrystalline mode phenomena with 2 polymorphs reported (forms A and B). Single crystals of the known crystalline form B and 3 new crystallosolvates involving bifendate solvated with tetrahydrofuran (C), dioxane (D), and pyridine (E) in a stoichiometric ratio of 1:1 were obtained and characterized by X-ray crystallography, thermal analysis, and Fourier transform infrared (FT-IR) spectroscopy. The differences in molecular conformation, intermolecular interaction and crystal packing arrangement for the four polymorphs were determined and the basis for the polymorphisms was investigated. The rotation of single bonds resulted in different orientations for the biphenyl, methyl ester and methoxyl groups. All guest solvent molecules interacted with the host molecule via an interesting intercalative mode along the [1 0 0] direction in the channel formed by the host molecules through weak aromatic stacking interactions or non-classical hydrogen bonds, of which the volume and planarity played an important role in the intercalation of the host with the guest. The incorporation of solvent-augmented rotation of the C-C bond of the biphenyl group had a striking effect on the host molecular conformation and contributed to the formation of bifendate polymorphs. Moreover, the simulated powder X-ray diffraction (PXRD) patterns for each form were calculated on the basis of the single-crystal data and proved to be unique. The single-crystal structures of the four crystalline forms are reported in this paper.

A water stable europium coordination polymer as fluorescent sensor for detecting Fe3+, CrO42-, and Cr2O72- ions

NASA Astrophysics Data System (ADS)

Chen, Chen; Zhang, Xiaolei; Gao, Peng; Hu, Ming

2018-02-01

A europium coordination polymer constructed by the 4‧-(4-carboxyphenyl)- 2,2‧:6‧,2″-terpyridine ligand (HL), namely, [EuL(CH3COO)Cl]n (1), has been prepared by the solvothermal method. Compound 1 was structurally characterized by the elemental analysis, FT-IR, powder X-ray diffractions (PXRD), thermogravimetric (TG) analysis, and single-crystal X-ray diffraction. Complex 1 displays a novel linear chain structure, which further extends to the 3D supramolecular structure via π···π and hydrogen bonds interactions. The luminescent properties of 1 were investigated in detail, which exhibit the fluorescent sensing for detecting Fe3+, CrO42-, and Cr2O72- ions in aqueous solution, respectively. In addition, 1 shows high sensitive and selective sensing for CrO42- and Cr2O72- anions with the great quenching efficiency. Furthermore, the luminescent sensing mechanisms of differentiating analytes are explored in detail. It is worth noting that there exists the weak interaction between Fe3+ ions and carboxylate oxygen atoms of CH3COO- groups through XPS characterization, resulting in the high quenching effect of 1.

Three coordination polymers constructed from 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid: Synthesis, crystal structure and properties

NASA Astrophysics Data System (ADS)

Zhai, Dandan; Sun, Wujuan; Fan, Fei; Liao, Xuzhao; Chen, Sanping; Yang, Xuwu

2017-04-01

Three new coordination polymers, namely, {[Co2(TPA)(μ3-O)3]·0.5DMA}n (1), {[Co(H2TPA)(bibp)(H2O)3]·H2O}n (2) and {[Cd3(TPA)2(phen)4]·4H2O}n (3), (H3TPA = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid, bibp = 4,4'-bis(imidazolyl)biphenyl, phen = 1,10-phenanthroline and DMA = N,N-dimethylacetamide), have been synthesized under solvothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analysis. Polymer 1 exhibits a three-dimensional (3D) structure constructed from 5-connected secondary building units (SBUs) [Co3(μ3-O)] and 3-connected H3TPA ligands. Polymer 2 has a 1D zigzag polymer chain connected by H3TPA and bibp ligands. Polymer 3 features an unusual 3D framework with a (3,4,2)-connected {4; 6;8}{4; 62;83} topology. Moreover, the thermal stabilities of 1-3 and photoluminescence properties of 3 have been investigated. Magnetic susceptibility measurements indicate that polymers 1-2 display antiferromagnetic exchange properties.

Different water clusters dependent on long-chain dicarboxylates in two Ag(I) coordination polymers: Synthesis, structure and thermal stability

NASA Astrophysics Data System (ADS)

Sun, Di; Liu, Fu-Jing; Hao, Hong-Jun; Huang, Rong-Bin; Zheng, Lan-Sun

2011-10-01

Two mixed-ligand Ag(I) coordination polymers (CPs), [Ag 2(bipy) 2(sub)·5H 2O] n ( 1), [Ag 2(bipy) 2(aze)·3H 2O] n ( 2), (bipy = 4,4'-bipyridine, H 2sub = suberic acid, H 2aze = azelaic acid) have been synthesized and structurally characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis, and single crystal X-ray diffraction. Both 1 and 2 are two-dimensional (2D) sheets based on infinite [Ag(bipy)] n double chain incorporating Ag⋯Ag interactions. Interestingly, two different water clusters are encapsulated in the voids between the sheets of 1 and 2. For 1, one water decamer (H 2O) 10 based on a cyclic water tetramer was hydrogen-bonded with the host 2D sheet. While, one water hexamer (H 2O) 6 also based on a cyclic water tetramer was observed in 2. Comparing the experimental results, it is comprehensible that the dicarboxylates play a crucial role in the formation of the different water clusters. Moreover, the thermal stabilities of them were also discussed.

Effect of sample preparation method on quantification of polymorphs using PXRD.

PubMed

Alam, Shahnwaz; Patel, Sarsvatkumar; Bansal, Arvind Kumar

2010-01-01

The purpose of this study was to improve the sensitivity and accuracy of quantitative analysis of polymorphic mixtures. Various techniques such as hand grinding and mixing (in mortar and pestle), air jet milling and ball milling for micronization of particle and mixing were used to prepare binary mixtures. Using these techniques, mixtures of form I and form II of clopidogrel bisulphate were prepared in various proportions from 0-5% w/w of form I in form II and subjected to x-ray powder diffraction analysis. In order to obtain good resolution in minimum time, step time and step size were varied to optimize scan rate. Among the six combinations, step size of 0.05 degrees with step time of 5 s demonstrated identification of maximum characteristic peaks of form I in form II. Data obtained from samples prepared using both grinding and mixing in ball mill showed good analytical sensitivity and accuracy compared to other methods. Powder x-ray diffraction method was reproducible, precise with LOD of 0.29% and LOQ of 0.91%. Validation results showed excellent correlation between actual and predicted concentration with R2 > 0.9999.

Visible-light-driven Bi 2 O 3 /WO 3 composites with enhanced photocatalytic activity

DOE PAGES

Adhikari, Shiba P.; Dean, Hunter; Hood, Zachary D.; ...

2015-10-19

Semiconductor heterojunctions (composites) have been shown to be effective photocatalytic materials to overcome the drawbacks of low photocatalytic efficiency that results from electron–hole recombination and narrow photo-response range. We prepared a novel visible-light-driven Bi 2O 3/WO 3 composite photocatalyst by hydrothermal synthesis. The composite was characterized by scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS) to better understand the structures, compositions, morphologies and optical properties. Bi 2O 3/WO 3 heterojunction was found to exhibit significantly higher photocatalyticmore » activity towards the decomposition of Rhodamine B (RhB) and 4-nitroaniline (4-NA) under visible light irradiation compared to that of Bi 2O 3 and WO 3. A tentative mechanism for the enhanced photocatalytic activity of the heterostructured composite is discussed based on observed activity, band position calculations, photoluminescence, and electrochemical impedance data. Our study provides a new strategy for the design of composite materials with enhanced visible light photocatalytic performance.« less

Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

NASA Astrophysics Data System (ADS)

Li, Yanzhou; Luo, Jie; Zhang, Yanting; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

2013-09-01

An inorganic-organic hybrid hexa-copper-substituted germanotungstate Na2[Cu(dap)2]2[Cu(dap)2] {[Cu6(H2O)2(dap)2][B-α-GeW9O34]2}·4H2O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP-AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O'Keefe) vertex symbol is 4·4·64·4·4·4·4·64·4·4·4·64·4·4·4 and the short vertex (Schläfli) symbol of 41263. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-CuII cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the WVI-based wave.

New SnO2/MgAl-layered double hydroxide composites as photocatalysts for cationic dyes bleaching.

PubMed

Dvininov, E; Ignat, M; Barvinschi, P; Smithers, M A; Popovici, E

2010-05-15

A new type of nanocomposite containing SnO(2) has been obtained by wet impregnation of dehydrated Mg/Al-hydrotalcite-type compounds with ethanolic solutions of SnCl(4).2H(2)O. Tin chloride hydrolysis was achieved using NaOH or NH(4)OH aqueous solutions, at pH around 9, followed by the conversion into corresponding hydroxides through calcinations. The powder X-ray diffraction (PXRD) and UV-Vis diffuse reflectance (UV-DR) methods confirmed the structure of as-synthesized solids. The chemical composition and morphology of the synthesized materials were investigated by energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-synthesized materials were used for photocatalytic studies showing a good activity for methylene blue decolourization, which varies with SnO(2) content and used as a hydrolysing agent. The proposed mechanism is based on the shifting of flat band potential of SnO(2) due to the interaction with Mg/Al-LDH, this being energetically favourable to the formation of hydroxyl radicals responsible for methylene blue degradation. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Room temperature synthesis of a Zn(II) metal-organic coordination polymer for dye removal

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

Abbasi, Alireza, E-mail: aabbasi@khayam.ut.ac.ir; Gharib, Maniya; Najafi, Mahnaz

2016-03-15

A new one-dimensional (1D) coordination polymer, [Zn(4,4′-bpy)(H{sub 2}O){sub 4}](ADC)·4H{sub 2}O (1) (4,4′-bpy=4,4′-bipyridine and H{sub 2}ADC=acetylenedicarboxylic acid), was synthesized at room temperature. The crystal structure of the coordination polymer was determined by single-crystal X-ray diffraction analysis. Compound 1 was also characterized by FT-IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The catalytic activity of 1 was evaluated in the color removal of Bismarck brown as a representative of dye pollutant in water under mild conditions. Coordination polymer 1 exhibited good catalytic activity and stability in the decolorization of Bismarck brown and could be easily recovered and reused for at leastmore » three cycles. - Graphical abstract: A new 1D coordination polymer as catalyst for the degradation of Bismarck brown aqueous solution. - Highlights: • A 1D coordination polymer has been synthesized at room temperature. • The prepared compound was utilized for color removal of Bismarck brown dye. • Good catalytic activity and stability in the dye decolorization has been found.« less

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.

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.

Comparison of structural and magnetic properties of Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} spinel oxides

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

Thummer, K. P., E-mail: kpthummer@yahoo.co.in; Tanna, A. R., E-mail: ashish.tanna@rku.ac.in; Joshi, H. H.

2016-05-23

The spinel oxides Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} (x = 0.0 to 0.6) and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} (x = 0.0 to 0.6) abbreviated as ZMMFO and MACFO respectively, were synthesized by standard ceramic processing. The compositional purity of all the specimens was checked by EDAX technique. The X-ray diffractometry was employed to determine the lattice constants and distribution of cations in the interstitial voids. The initial decrease of cell edge parameter (a) for ZMMFO up to x = 0.2 and thereafter expected rise in the ‘a’ and the initial slower rate of reduction in the lattice constant formore » MACFO are explained as basic of cation occupancy. The magnetic ordering in both systems is explained by invoking statistical canting models. The compositional variation of magneton number (n{sub B}) for ZMMFO could be very well explained by Localized canting of spin (LCS) model while Random canting of spin (RCS) model was used for MACFO system.« less

Comparative analysis of strain fields in layers of step-graded metamorphic buffers of various designs

NASA Astrophysics Data System (ADS)

Aleshin, A. N.; Bugaev, A. S.; Ruban, O. A.; Tabachkova, N. Yu.; Shchetinin, I. V.

2017-10-01

Spatial distribution of residual elastic strain in the layers of two step-graded metamophic buffers of various designs, grown by molecular beam epitaxy from ternary InxAl1-xAs solutions on GaAs(001) substrates, is obtained using reciprocal space mapping by three-axis X-ray diffractometry and the linear theory of elasticity. The difference in the design of the buffers enabled the formation of a dislocation-free layer with different thickness in each of the heterostructures, which was the main basis of this study. It is shown that, in spite of the different design of graded metamorphic buffers, the nature of strain fields in them is the same, and the residual elastic strains in the final elements of both buffers adjusted for the effect of work hardening subject to the same phenomenological law, which describes the strain relief process in single-layer heterostructures.

Cd(II)-coordination polymers based on tetracarboxylic acid and diverse bis(imidazole) ligands: Synthesis, structural diversity and photoluminescence properties

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

Arıcı, Mürsel, E-mail: marici@ogu.edu.tr; Yeşilel, Okan Zafer; Taş, Murat

Three new Cd(II)-coordination polymers, namely, ([Cd{sub 2}(μ{sub 6}-ao{sub 2}btc)(μ-1,5-bipe){sub 2}]·2H{sub 2}O){sub n} (1), ([Cd{sub 2}(μ{sub 6}-ao{sub 2}btc)(μ-1,4-bix){sub 2}]{sub n}·2DMF) (2) and ([Cd{sub 2}(μ{sub 8}-abtc)(μ-1,4-betix)]·DMF·H{sub 2}O){sub n} (3) (ao{sub 2}btc=di-oxygenated form of 3,3′,5,5′-azobenzenetetracarboxylate, 1,5-bipe: 1,5-bis(imidazol-1yl)pentane, 1,4-bix=1,4-bis(imidazol-1ylmethyl)benzene, 1,4-betix=1,4-bis(2-ethylimidazol-1ylmethyl)benzene) were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1–3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the raremore » sqc27 topology. When semi-flexible substituted bis(imidazole) linker was used, 3D framework of complex 3 was obtained with the paddlewheel Cd{sub 2}(CO{sub 2}){sub 4}-type binuclear SBU. Moreover, thermal and photoluminescence properties of the complexes were determined in detailed. - Graphical abstract: In this study, three novel Cd(II)-coordination polymers were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1–3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the rare sqc27 topology. When semi-flexible substituted bis(imidazole) linker was used, 3D framework of complex 3 was obtained with the paddlewheel Cd{sub 2}(CO{sub 2}){sub 4}-type binuclear SBU. - Highlights: • Three new Cd(II)-coordination polymers with azobenzenetetracarboxylic acid and diverse bis(imidazole) linkers. • Complex 1 is 2D structure with 3,6L18 topology. • 3D pillar-layered framework of 2 with the rare sqc27 topology. • 3D framework of 3 with the paddlewheel Cd{sub 2}(CO{sub 2}){sub 4}-type SBU.« less

Mimosa pudica (L.) assisted green synthesis and photoluminescence studies of Y2O3:Mg2+ nanophosphor for display applications

NASA Astrophysics Data System (ADS)

Venkatachalaiah, KN; Venkataravanappa, M.; Nagabhushana, H.; Basavaraj, R. B.

2016-09-01

For the first time green route method was used to synthesize pure and Mg2+(1-11 mol %) doped Y2O3 nanophosphors by using Mimosa pudica leaves extract as a fuel. The final product was well characterized by powder x-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL).The PXRD result shows the formation of single phase, cubic structure of Y2O3 with crystallite sizes ∼25 nm. The SEM results showed porous and agglomerated structures, TEM images showed the crystallite size of the material and was found to be around ∼ 25 nm. PL emission spectra show the blue light emission under the excitation wavelength of 315 nm. The emission peaks of Mg2+were observed at 428 nm, 515 nm and 600 nm corresponding to the transitions of 4F9/2 → 6Hi7/2 (violet), 4F9/2 → 6Hi5/2 (blue), 4F9/2 → 6HJ3/2 (yellow) respectively. The estimated CIE chromaticity co-ordinate was very close to the national television standard committee value of blue emission. CCT was found to be ∼ 6891 K as a result the present phosphor was potential to be used for warm white light emitting display applications.

Ultrasound assisted sonochemical synthesis of samarium doped Y2O3 nanostructures for display applications

NASA Astrophysics Data System (ADS)

Venkatachalaiah, K. N.; Nagabhushana, H.; Basavaraj, R. B.; Venkataravanappa, M.; Suresh, C.

2018-04-01

Sm3+ doped (1-11 mol %) cubic Y2O3 nanoflowers were fabricated by simple low temperature Sonochemical method using Aloe Vera gel as fuel. The product was characterized by PXRD, SEM, TEM, DRS, PL etc. The powder X-ray diffraction (PXRD) profiles of nanophosphors showed cubic phase structure. The particle size was further confirmed by transmission electron microscope (TEM) and it was found to be in the range of 17-25 nm. The PL emission results reveal that the phosphor nanoparticles (NPs) emit an intensive yellowish light under 367 nm excitation. The excitation spectrum of Y2O3: Sm3+ (5 mol %) obtained by monitoring the emission of the 4f - 4f (4G5/2→6H7/2) transition of Sm3+ at 612 nm As can be seen that the excitation spectrum consists of strong band at 332 nm and a broad band centered at 367 nm which corresponds to host absorption, confirming the effective energy transfer from Y2O3 host to Sm3+ ions. In the present study, CIE and CCT were estimated and found to be (0.45688, 0.51727) and the CCT of Y2O3: Sm3+ at 367 nm excitation was found to be 3357 K which was within the range of vertical daylight. Thus it can be useful for artificial production of illumination devices.

Erythritol: crystal growth from the melt.

PubMed

Lopes Jesus, A J; Nunes, Sandra C C; Ramos Silva, M; Matos Beja, A; Redinha, J S

2010-03-30

The structural changes occurring on erythritol as it is cooled from the melt to low temperature, and then heated up to the melting point have been investigated by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM), X-ray powder diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). By DSC, it was possible to set up the conditions to obtain an amorphous solid, a crystalline solid, or a mixture of both materials in different proportions. Two crystalline forms have been identified: a stable and a metastable one with melting points of 117 and 104 degrees C, respectively. The fusion curve decomposition of the stable form revealed the existence of three conformational structures. The main paths of the crystallization from the melt were followed by PLTM. The texture and colour changes allowed the characterization of the different phases and transitions in which they are involved on cooling as well as on heating processes. The type of crystallization front and its velocity were also followed by microscopic observation. These observations, together with the data provided by PXRD, allowed elucidating the transition of the metastable form into the stable one. The structural changes occurring upon the cooling and subsequent heating processes, namely those arising from intermolecular hydrogen bonds, were also accompanied by infrared spectroscopy. Particular attention was given to the spectral changes occurring in the OH stretching region. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Characterization of a nonribosomal peptide antibiotic solid dispersion formulation by process analytical technologies sensors.

PubMed

Rahman, Ziyaur; Siddiqui, Akhtar; Khan, Mansoor A

2013-12-01

The focus of present investigation was to characterize and evaluate the variability of solid dispersion (SD) of amorphous vancomycin (VCM), utilizing crystalline polyethylene glycol (PEG-6000) as a carrier and subsequently, determining their percentage composition by nondestructive method of process analytical technology (PAT) sensors. The SD were prepared by heat fusion method and characterized for physicochemical and spectral properties. Enhanced dissolution was shown by the SD formulations. Decreased crystallinity of PEG-6000 was observed indicating that the drug was present as solution and dispersed form within the polymer. The SD formulations were homogenous as shown by near infrared (NIR) chemical imaging data. Principal component analysis (PCA) and partial least square (PLS) method were applied to NIR and PXRD (powder X-ray diffraction) data to develop model for quantification of drug and carrier. PLS of both data showed correlation coefficient >0.9934 with good prediction capability as revealed by smaller value of root mean square and standard error. The model based on NIR and PXRD were two folds more accurate in estimating PEG-6000 than VCM. In conclusion, the drug dissolution from the SD increased by decreasing crystallinity of PEG-6000, and the chemometric models showed usefulness of PAT sensor in estimating percentage of both VCM and PEG-600 simultaneously. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Multistimuli-responsive benzothiadiazole-cored phenylene vinylene derivative with nanoassembly properties.

PubMed

Dou, Chuandong; Chen, Dong; Iqbal, Javed; Yuan, Yang; Zhang, Hongyu; Wang, Yue

2011-05-17

A trifluoromethyl-substituted benzothiadiazole-cored phenylene vinylene fluorophore (1) was synthesized and displayed piezo- and vapochromism and thermo-induced fluorescence variation in solid phase. Grinding could disrupt the crystalline compound 1 with orange emission into amorphous compound 1 with green emission, and heating treatment could change the amorphous compound 1 into crystalline compound 1. Ultraviolet-visible (UV-vis) absorption spectra, (13)C nuclear magnetic resonance (NMR), and powder X-ray diffraction (PXRD) characterizations demonstrated that crystalline and amorphous compound 1 possess different molecular packing. A differential scanning calorimetry (DSC) measurement revealed that the emission switching was due to the exchange between the thermodynamic-stable crystalline and metastable amorphous states. The ground sample exhibited vapochromic fluorescence property. Furthermore, compound 1 showed interesting supramolecular assembly characteristics in solution. Slowly cooling the hot N,N-dimethylformamide (DMF) solution of compound 1 resulted in the formation of orange fluorescent fibers, whereas sonication treatment of the cooling solution led to the generation of organic molecular gel. The field emission scanning electronic microscope (FESEM) and fluorescent microscopy images revealed smooth nano- or microfiber and network morphology properties. The PXRD spectra confirmed that these nano- or microstructures had a similar molecular-packing model with the crystalline state of compound 1. Slow evaporation of the toluene solution of compound 1 could produce green emissive microrods, which exhibited interesting thermo-induced fluorescence variation.

The conversion process of hydrocarbon hydrates into CO2 hydrates and vice versa: thermodynamic considerations.

PubMed

Schicks, J M; Luzi, M; Beeskow-Strauch, B

2011-11-24

Microscopy, confocal Raman spectroscopy and powder X-ray diffraction (PXRD) were used for in situ investigations of the CO(2)-hydrocarbon exchange process in gas hydrates and its driving forces. The study comprises the exposure of simple structure I CH(4) hydrate and mixed structure II CH(4)-C(2)H(6) and CH(4)-C(3)H(8) hydrates to gaseous CO(2) as well as the reverse reaction, i.e., the conversion of CO(2)-rich structure I hydrate into structure II mixed hydrate. In the case of CH(4)-C(3)H(8) hydrates, a conversion in the presence of gaseous CO(2) from a supposedly more stable structure II hydrate to a less stable structure I CO(2)-rich hydrate was observed. PXRD data show that the reverse process requires longer initiation times, and structural changes seem to be less complete. Generally, the exchange process can be described as a decomposition and reformation process, in terms of a rearrangement of molecules, and is primarily induced by the chemical potential gradient between hydrate phase and the provided gas phase. The results show furthermore the dependency of the conversion rate on the surface area of the hydrate phase, the thermodynamic stability of the original and resulting hydrate phase, as well as the mobility of guest molecules and formation kinetics of the resulting hydrate phase.

Preparation, structural analysis, and properties of tenoxicam cocrystals.

PubMed

Patel, Jagdishwar R; Carlton, Robert A; Needham, Thomas E; Chichester, Clinton O; Vogt, Frederick G

2012-10-15

Cocrystals of tenoxicam, a non-steroidal anti-inflammatory drug, are screened, prepared, and characterized in this study. Nine tenoxicam cocrystals were identified using solvent-drop grinding (SDG) techniques. Structural characterization was performed using powder X-ray diffraction (PXRD), differential scanning calorimetry, and multinuclear solid-state NMR (SSNMR). Thermal analysis, PXRD, and 1D SSNMR are used to detect solvates and phase mixtures encountered in SDG cocrystal screening. 2D SSNMR methods are then used to confirm cocrystal formation and determine structural aspects for selected cocrystals formed with saccharin, salicylic acid, succinic acid, and glycolic acid in comparison to Forms I and III of tenoxicam. Molecular association is demonstrated using cross-polarization heteronuclear dipolar correlation (CP-HETCOR) methods involving (1)H and (13)C nuclei. Short-range (1)H-(13)C CP-HETCOR and (1)H-(1)H double-quantum interactions between atoms of interest, including those engaged in hydrogen bonding, are used to reveal local aspects of the cocrystal structure. (15)N SSNMR is used to assess ionization state and the potential for zwitterionization in the selected cocrystals. The tenoxicam saccharin cocrystal was found to be similar in structure to a previously-reported cocrystal of piroxicam and saccharin. The four selected cocrystals yielded intrinsic dissolution rates that were similar or reduced relative to tenoxicam Form III. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of the solid state properties of amoxicillin trihydrate and the effect of powder pH.

PubMed

Ghassempour, Alireza; Rafati, Hasan; Adlnasab, Laleh; Bashour, Yosef; Ebrahimzadeh, Homeira; Erfan, Mohammad

2007-11-09

The purpose of this research was to investigate some physicochemical and solid-state properties of amoxicillin trihydrate (AMT) with different powder pH within the pharmacopoeia-specified range. AMT batches prepared using Dane salt method with the pH values from 4.39 to 4.97 were subjected to further characterization studies. Optical and scanning electron microscopy showed that different batches of AMT powders were similar in crystal habit, but the length of the crystals increased as the pH increased. Further solid-state investigations using powder x-ray diffraction (PXRD) demonstrated the same PXRD pattern, but the intensity of the peaks raised by the powder pH, indicated increased crystallinity. Differential scanning calorimetry (DSC) studies further confirmed that as the powder pH increased, the crystallinity and, hence, thermal stability of AMT powders increased. Searching for the possible cause of the variations in the solid state properties, HPLC analysis showed that despite possessing the requirements of the United States Pharmacopoeia (USP) for purity/impurity profile, there was a direct relationship between the increase of the powder pH and the purity of AMT, and also decrease in the impurity I (alpha-Hydroxyphenylglycine) concentration in AMT powder. Recrystallization studies confirmed that the powder pH could be controlled by adjusting the pH of the crystallization.

Synthesis and investigation of proton conductivity for intercalated kaolinite with 4-amidinopyridinium chloride

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

Ren, Li-Te; College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009; Li, Xiao-Pei

2015-12-15

The proton-conducting materials have potential application in devices such as fuel cells. In this study, a mineral kaolinite-based proton conducting material, kaolinite-4-amidinopyridinium hydrochloride (K-4-APy–HCl), was synthesized by the intercalated compound kaolinite-4-amidinopyridine (K-4-APy) adsorbing volatilizing HCl. The thermogravimetric analysis (TG), powder X-ray diffraction (PXRD) and IR spectrum confirmed the HCl successfully inserting into the interlayer space of kaolinite and the 4-aminopyridine being protonated. The intercalation efficiency is estimated to be ca. 85.6%. With respect to K-4-APy, the interlayer space expends by 1.53 Å. The thermal decomposition mechanism was studied by PXRD and TG techniques. The K-4-APy–HCl shows proton conductivity with σ=3.379×10{supmore » −8} S cm{sup −1} at 373 K and E{sub a}=1.159 eV in the anhydrous condition, which are comparable to MOFs-based proton conducting materials. - Graphical abstract: The intercalated hybrid of mineral kaolinite with 4-amidinopyridinium hydrochloride is prepared to use as proton conducting material. - Highlights: • A new strategy is proposed for preparation of kaolinite-based proton conductor. • Intercalatied hybrid was prepared by sequentially inserting 4-amidinopyridine and adsorbing HCl. • The proton conductivity of intercalated hybrid is comparable to MOFs-based proton-conductors.« less

[Subtype classification of ceftriaxone sodium and its influence on the quality of product].

PubMed

Xue, Jing; Jia, Yan-Hua; Li, Jin; Yin, Li-Hui; Hu, Chang-Qin

2014-07-01

Powder X-ray diffraction (PXRD) technology combined with cluster analysis method was used to classify 75 batches of crystalline ceftriaxone sodium into subtypes, the crystalline characteristics of each subtype were measured with scanning electron microscope (SEM). By comparing some parameters of these subtypes correlated to crystallization process of ceftriaxone sodium, such as salification rate, water content in different subtypes, as well as by studying different lattice stabilities, different compatibilities with rubber closures during accelerated stability tests, the key point to improve the quality of domestic ceftriaxone sodium was disclosed. The results of this paper indicated that the fine structure of the products could be controlled well by improving the salification and crystallization process. As a result, the subtype II of ceftriaxone sodium with high stability can be produced.

Syntheses, crystal structures and properties of series of 4d-4f ln(III)-Ag(I) heterometallic coordination polymers

NASA Astrophysics Data System (ADS)

Ran, Xing-Rui; Wang, Ning; Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian; Long, Yi; Yue, Shan-Tang; Liu, Ying-Liang

2015-05-01

By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d-4f Ln(III)-Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, {[LnIIIAgI(na)(ina)(ox)]·2(H2O)}n [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail.

Hydrothermally synthesized flower like MoS2 microsphere: A highly efficient adsorbent for methylene blue dye removal

NASA Astrophysics Data System (ADS)

Panda, Jnanranjan; Tudu, Bharati

2018-05-01

Herein, a flower like MoS2 (M1) microsphere assembled by layered porous nanosheet was successfully prepared by facile hydrothermal synthesis procedure. The structural, chemical and morphological characterizations for the as synthesized sample (M1) were carried out by powder x-ray diffraction (PXRD), Fourier-transform infrared (FTIR) and Field Emission Scanning Electron microscope (FESEM) respectively and spectroscopic characterization was performed by UV-Vis absorption and photoluminescence emission spectroscopy. The photocatalytic activity of the product was evaluated through photocatalytic degradation of Methylene Blue under visible light irradiation. The results indicate that layered MoS2structures possess significant adsorption ability, which may be useful for further research and practical applications of the layered MoS2 adsorbent in wastewater treatment.

Enhancing the bioavailability of mebendazole by integrating the principles solid dispersion and nanocrystal techniques, for safe and effective management of human echinococcosis.

PubMed

Chaudhary, Sushant; Garg, Tarun; Rath, Goutam; Murthy, Rs Rayasa; Goyal, Amit K

2016-05-01

The method based on integrating the principles of solid dispersion and nanocrystal techniques was developed to prepare polymer crystals (PCs) of mebendazole (MBZ) and polyethylene glycol (PEG). Powder X-Ray diffraction (PXRD) of the PC crystals shows the required integrated crystalline and amorphous regions. The in vitro solubility studies showed a 32-fold increase in the solubility of the drug. Tests of dissolution of the PCs showed that the crystals have an enhanced dissolution rate in comparison to those in the MF. The results of the pharmacokinetic study showed a 2.12-fold increase in the bioavailability of the drug. Thus, the present study has proved the potential in enhancing solubility, dissolution, and bioavailability of the drug.

High-throughput syntheses of iron phosphite open frameworks in ionic liquids

NASA Astrophysics Data System (ADS)

Wang, Zhixiu; Mu, Ying; Wang, Yilin; Bing, Qiming; Su, Tan; Liu, Jingyao

2017-02-01

Three open-framework iron phosphites: Feп5(NH4)2(HPO3)6 (1), Feп2Fe♯(NH4)(HPO3)4 (2) and Fe♯2(HPO3)3 (3) have been synthesized under ionothermal conditions. How the different synthesis parameters, such as the gel concentrations, synthetic times, reaction temperatures and solvents affect the products have been monitored by using high-throughput approaches. Within each type of experiment, relevant products have been investigated. The optimal reaction conditions are obtained from a series of experiments by high-throughput approaches. All the structures are determined by single-crystal X-ray diffraction analysis and further characterized by PXRD, TGA and FTIR analyses. Magnetic study reveals that those three compounds show interesting magnetic behavior at low temperature.

Green engineered ZnO nanopowders by Banyan Tree and E. tirucalli plant latex: auto ignition route, photoluminescent and photocatalytic properties

NASA Astrophysics Data System (ADS)

Anilkumar, M. R.; Nagaswarupa, H. P.; Anantharaju, K. S.; Gurushantha, K.; Pratapkumar, C.; Prashantha, S. C.; Shashi Shekhar, T. R.; Nagabhushana, H.; Sharma, S. C.; Vidya, Y. S.; Prasad, Daruka

2015-03-01

A simple and eco-friendly solution combustion route was used to prepare ZnO nanoparticles (ZNPs) using Banyan Tree (BT) and Euphorbia tirucalli (ET) plant latexes as fuels. The final products were characterized by powder x-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), UV-visible, scanning electron microcopy (SEM) and transmission electron microscopy (TEM). The PXRD result reveals the formation of hexagonal phase with Wurtzite structure. The crystallite size obtained from TEM was found to be ˜20-25 nm. SEM results reveal rose-like morphology with BT latex and hexagonal shaped with ET latex. The energy band gap of ZNPs obtained by BT and ET latex were found to be 3.20 and 3.38 eV, respectively. Photoluminescence (PL) emission peaks at ˜421, 458, 505, 522, 628 and 695 nm were observed in both the samples when excited at 383 nm. These emission peaks were mainly attributed to deep level oxygen (blue-green) defect and exciton (UV) defects, respectively. The international commission on illumination (CIE) chromaticity co-ordinates, as well as co-ordinated color temperature (CCT), were estimated from the emission spectra; the values (x, y) were very close to national television system committee (NTSC) standard values of pure white emission. Photocatalytic activity (PCA) of ZNPs prepared was studied in detail. The ZNPs prepared using BT latex showed highest PCA under sunlight. The results demonstrate that the synthesized product could be quite useful for display applications as well as photocatalyst. Further, the material prepared by this route was found to be non-toxic, environmentally friendly and could be a potential alternative to economical routes.

Nitriding of titanium and titanium: 8 percent aluminum, 1 percent molybdenum, 1 percent vanadium alloy with an ion-beam source

NASA Technical Reports Server (NTRS)

Gill, A.

1983-01-01

Titanium and Ti-8Al-1Mo-1V alloy were nitrided with an ion-beam source of nitrogen or argon and nitrogen at a total pressure of 2 x 10 to the minus 4th power to 10 x 10 to the minus 4th power torr. The treated surface was characterized by surface profilometry, X-ray diffractometry, Auger electron spectroscopy and microhardness measurements. The tetragonal Ti2N phase formed in pure titanium and Ti-8Al-1Mo-1V alloy with traces of AlN in the alloy. Two opposite processes competed during the ion-beam-nitriding process: (1) formation of nitrides in the surface layer and (2) sputtering of the nitrided layers by the ion beam. The highest surface hardnesses, about 500 kg/sq mm in titanium and 800 kg/sq mm in Ti-8Al-1Mo-1V, were obtained by ion nitriding with an ion beam of pure nitrogen at 4.2 x 10 to the minus 4th power torr at a beam voltage of 1000 V.

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.

Synthesis of Single Crystalline ZnO Nanoparticles by Salt-Assisted Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Panatarani, Camellia; Lenggoro, I. Wuled; Okuyama, Kikuo

2003-04-01

LiNO3 was used as a shield in the preparation of single crystalline ZnO particles by a spray pyrolysis process in order to prevent agglomeration and enhance the crystallinity of the ZnO. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor.

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.

Growth of indium gallium arsenide thin film on silicon substrate by MOCVD technique

NASA Astrophysics Data System (ADS)

Chowdhury, Sisir; Das, Anish; Banerji, Pallab

2018-05-01

Indium gallium arsenide (InGaAs) thin film with indium phosphide (InP) buffer has been grown on p-type silicon (100) by Metal Organic Chemical Vapor Deposition (MOCVD) technique. To get a lattice matched substrate an Indium Phosphide buffer thin film is deposited onto Si substrate prior to InGaAs growth. The grown films have been investigated by UV-Vis-NIR reflectance spectroscopy. The band gap energy of the grown InGaAs thin films determined to be 0.82 eV from reflectance spectrum and the films are found to have same thickness for growth between 600 °C and 650 °C. Crystalline quality of the grown films has been studied by grazing incidence X-ray diffractometry (GIXRD).

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.

Optical Fourier diffractometry applied to degraded bone structure recognition

NASA Astrophysics Data System (ADS)

Galas, Jacek; Godwod, Krzysztof; Szawdyn, Jacek; Sawicki, Andrzej

1993-09-01

Image processing and recognition methods are useful in many fields. This paper presents the hybrid optical and digital method applied to recognition of pathological changes in bones involved by metabolic bone diseases. The trabecular bone structure, registered by x ray on the photographic film, is analyzed in the new type of computer controlled diffractometer. The set of image parameters, extracted from diffractogram, is evaluated by statistical analysis. The synthetic image descriptors in discriminant space, constructed on the base of 3 training groups of images (control, osteoporosis, and osteomalacia groups) by discriminant analysis, allow us to recognize bone samples with degraded bone structure and to recognize the disease. About 89% of the images were classified correctly. This method after optimization process will be verified in medical investigations.

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.

Removal of р-nitrophenol from aqueous solution by magnetically modified activated carbon

NASA Astrophysics Data System (ADS)

Han, Shuai; Zhao, Feng; Sun, Jian; Wang, Bin; Wei, Rongyan; Yan, Shiqiang

2013-09-01

Activated carbon was modified with γ-Fe2O3 nanoparticles, using the chemical co-precipitation technique and the carboxylic acid vapor treatment technique. Two magnetic composites were characterized and compared by Fourier Transform Infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry and nitrogen adsorption-desorption. Then the two materials were used to remove p-nitrophenol in water. The equilibrium data revealed that the Langmuir isotherm was better in fitting the experiment result than the Freundlich isotherm, and the sorption capacity of the nanocomposite made by the chemical co-precipitation technique was higher than that of the other one. We suggest that the chemical co-precipitation technique is a more efficient and practical method to produce magnetically modified activated carbon.

Clay-mineraloid weathering products in Antarctic meteorites

NASA Technical Reports Server (NTRS)

Gooding, James L.

1986-01-01

The production of clay mineraloids (CMs) in the weathering of stony meteorites recovered in the Allan Hills and Elephant Moraine areas of Antarctica is investigated, applying electron microbeam analysis, pyrolysis/mass spectroscopy, X-ray diffractometry, and differential scanning calorimetry to whole-rock chips from two eucrites, two diogenites, and an H5 chondrite. The data are presented in tables, graphs, and photomicrographs and characterized in detail. Massive to incipient-vermicular CM formations with smectitelike or micalike compositions and indications of poor crystallization are observed and attributed to hydrocryogenic diagenesis (with little or no liquid water) on time scales of 10-1000 kyr. The need to take the compositional effects of weathering into account before attempting to reconstruct the preterrestrial histories of meteorites is stressed.

Lattice distortion and strain relaxation in epitaxial thin films of multiferroic TbMnO3 probed by X-ray diffractometry and micro-Raman spectroscopy

NASA Astrophysics Data System (ADS)

Hu, Y.; Stender, D.; Medarde, M.; Lippert, T.; Wokaun, A.; Schneider, C. W.

2013-08-01

A detailed structural XRD analysis of (1 1 0)-oriented TbMnO3 thin films grown on (1 1 0)-YAlO3 substrates shows the co-existence of a strained and relaxed "sublayer" within the films due to strain relaxation during epitaxial growth by pulsed laser deposition. The substrate-film lattice mismatch yields a compressive strain anisotropy along the two in-plane directions, i.e. [1 -1 0] and [0 0 1] and a monoclinic distortion. A further manifestation of the growth-induced strain is the hardening of Raman active modes as a result of changed atomic motions along the [1 -1 0] and [0 0 1] directions.

A new nanospray drying method for the preparation of nicergoline pure nanoparticles

NASA Astrophysics Data System (ADS)

Martena, Valentina; Censi, Roberta; Hoti, Ela; Malaj, Ledjan; Di Martino, Piera

2012-06-01

Three different batches of pure nanoparticles (NPs) of nicergoline (NIC) were prepared by spray drying a water:ethanol solution by a new Nano Spray Dryer Büchi B-90. Spherical pure NPs were obtained, and several analytical techniques such as differential scanning calorimetry and X-ray powder diffractometry permitted to assess their amorphous character. A comparison of the solubility, intrinsic dissolution, and drug release of original particles and pure amorphous NPs were determined, revealing an interesting improvement of biopharmaceutical properties of amorphous NPs, due to both amorphous properties and nanosize dimensions. Since in a previous work, the high-thermodynamic stability of amorphous NIC was demonstrated, this study is addressed toward the formulation of NIC as pure amorphous NPs.

A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy

PubMed Central

Trivedi, Mahendra Kumar; Sethi, Kalyan Kumar; Panda, Parthasarathi; Jana, Snehasis

2017-01-01

Objective: Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. Materials and Methods: The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques. Results: The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70–55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 (d10), 3.025 (d50), and 6.712 (d90) μm and average surface area of 2.71 m2/g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed Tmax at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λmax), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn–Cl stretching. Conclusions: These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications. PMID:28405577

Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1-Butyl-3-Methylimidazolium Ionic Liquids and Propylene Carbonate.

PubMed

Schütte, Kai; Barthel, Juri; Endres, Manuel; Siebels, Marvin; Smarsly, Bernd M; Yue, Junpei; Janiak, Christoph

2017-02-01

Decomposition of transition-metal amidinates [M{MeC(N i Pr) 2 } n ] [M(AMD) n ; M=Mn II , Fe II , Co II , Ni II , n= 2; Cu I , n= 1) induced by microwave heating in the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1-butyl-3-methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition-metal nanoparticles (M-NPs) in non-fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF 2 -NPs) for M=Mn, Fe, and Co in [BMIm][BF 4 ]. FeF 2 -NPs can be prepared upon Fe(AMD) 2 decomposition in [BMIm][BF 4 ], [BMIm][PF 6 ], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6 weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF 4 ] were identified by powder X-ray diffraction (PXRD) to exclusively Ni- and Cu-NPs or to solely MF 2 -NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4) nm for the M-NPs, except for the Cu-NPs in PC, which were 51(±8) nm. The MF 2 -NPs from [BMIm][BF 4 ] were 15(±4) to 65(±18) nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy-dispersive X-ray spectroscopy (EDX). Electrochemical investigations of the CoF 2 -NPs as cathode materials for lithium-ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF 2 -NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles.

In-situ X-ray diffraction activation study on an Fe/TiO2 pre-catalyst.

PubMed

Rayner, Matthew K; Billing, David G; Coville, Neil J

2014-06-01

This study focuses on the use of in situ powder X-ray diffraction (PXRD) and quantitative phase analysis using the Rietveld method to monitor the structural properties of a titania-supported iron (10% Fe/TiO2) pre-catalyst during calcination (oxidation) and activation (reduction) in the temperature range 25-900°C. The TiO2 oxidation study revealed an increase in anatase particle size before the anatase to rutile phase transformation, lending credibility to the bridging mechanism proposed by Kim et al. [(2007), Mater. Sci. Forum, 534-536, 65-68]. Pre-catalyst oxidation experiments allowed for the determination of a suitable calcination temperature (450°C) of the pre-catalyst in terms of maximum hematite concentration and appropriate particle size. These experiments also confirmed that the anatase to rutile phase transformation occurred at higher temperatures after Fe addition and that anatase was the sole donor of Ti(4+) ions, which are known to migrate into hematite (Gennari et al., 1998), during the formation of pseudobrookite (Fe2TiO5) at temperatures above 690°C. Using the results from the oxidation experiments, two pre-catalyst samples were calcined at different temperatures; one to represent the preferred case and one to represent a case where the pre-catalyst had been excessively heated. Samples of the excessively heated catalysts were exposed to different reducing gas atmospheres (5, 10 and 100% H2/N2) and heated in the in situ PXRD reactor, so that diffraction data could be collected during the activation process. The results show that reduction with gases containing low concentrations of H2 (5 and 10%) led to the formation of ilmenite (FeTiO3) and we were able to show that both anatase and rutile are consumed in the reaction. Higher concentrations of H2 led to the formation of magnetite (Fe3O4) and metallic iron (Fe(0)). We also noted a decrease in the anatase to rutile transformation temperature under reducing atmospheres when compared with the pre-catalyst heat-treatment experiment. A reduced calcination temperature prior to reduction allowed more facile Fe reduction.

A comprehensive physicochemical, thermal, and spectroscopic characterization of zinc (II) chloride using X-ray diffraction, particle size distribution, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetric analysis, ultraviolet-visible, and Fourier transform-infrared spectroscopy.

PubMed

Trivedi, Mahendra Kumar; Sethi, Kalyan Kumar; Panda, Parthasarathi; Jana, Snehasis

2017-01-01

Zinc chloride is an important inorganic compound used as a source of zinc and has other numerous industrial applications. Unfortunately, it lacks reliable and accurate physicochemical, thermal, and spectral characterization information altogether. Hence, the authors tried to explore in-depth characterization of zinc chloride using the modern analytical technique. The analysis of zinc chloride was performed using powder X-ray diffraction (PXRD), particle size distribution, differential scanning calorimetry (DSC), thermogravimetric analysis/differential thermogravimetric analysis (TGA/DTG), ultraviolet-visible spectroscopy (UV-vis), and Fourier transform-infrared (FT-IR) analytical techniques. The PXRD patterns showed well-defined, narrow, sharp, and the significant peaks. The crystallite size was found in the range of 14.70-55.40 nm and showed average crystallite size of 41.34 nm. The average particle size was found to be of 1.123 ( d 10 ), 3.025 ( d 50 ), and 6.712 ( d 90 ) μm and average surface area of 2.71 m 2 /g. The span and relative span values were 5.849 μm and 1.93, respectively. The DSC thermogram showed a small endothermic inflation at 308.10°C with the latent heat (ΔH) of fusion 28.52 J/g. An exothermic reaction was observed at 449.32°C with the ΔH of decomposition 66.10 J/g. The TGA revealed two steps of the thermal degradation and lost 8.207 and 89.72% of weight in the first and second step of degradation, respectively. Similarly, the DTG analysis disclosed T max at 508.21°C. The UV-vis spectrum showed absorbance maxima at 197.60 nm (λ max ), and FT-IR spectrum showed a peak at 511/cm might be due to the Zn-Cl stretching. These in-depth, comprehensive data would be very much useful in all stages of nutraceuticals/pharmaceuticals formulation research and development and other industrial applications.

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.

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.

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.

Electronic structure and bonding interactions in Ba1- x Sr x Zr0.1Ti0.9O3 ceramics

NASA Astrophysics Data System (ADS)

Mangaiyarkkarasi, Jegannathan; Sasikumar, Subramanian; Saravanan, Olai Vasu; Saravanan, Ramachandran

2017-06-01

An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1- x Sr x Zr0.1Ti0.9O3 (short for BSZT, x = 0, 0.05, 0.07 and 0.14) ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method (MEM). Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiO3 structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.

A nanoporous 3D zinc(II) metal–organic framework for selective absorption of benzaldehyde and formaldehyde

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

Moradpour, Tahereh; Abbasi, Alireza, E-mail: aabbassi@khayam.ut.ac.ir; Van Hecke, Kristof

A new 3D nanoporous metal–organic framework (MOF), [[Zn{sub 4}O(C{sub 24}H{sub 15}N{sub 6}O{sub 6}){sub 2}(H{sub 2}O){sub 2}]·6H{sub 2}O·DMF]{sub n} (1) based on 4,4′,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB) ligand was solvothermally synthesized and characterized by single–crystal X-ray diffraction, Powder X-ray diffraction (PXRD), infrared spectroscopy (IR) and Brunauer–Emmett–Teller (BET) analyses. X-ray single crystal diffraction analysis reveals that 1 exhibits a 3D network with new kvh1 topology. Semi-empirical (AM1) calculations were carried out to obtain stable conformers for TATAB ligand. In addition, the absorption of two typical aldehydes (benzaldehyde and formaldehyde) in the presence of 1 was investigated and the effect of the aldehyde concentration, exposure timemore » and temperature was studied. It was found that compound 1 has a potential for the absorption of aldehydes under mild conditions. - Graphical abstract: Absorption of two typical aldehydes (formaldehyde and benzaldehyde) by solvothermally synthesized of a 3D nano-porous MOF based on TATAB tricarboxylate ligand and Zn (NO{sub 3}){sub 2}·6H{sub 2}O. - Highlights: • We present a 3D Zn(II)-MOF with TATAB linker by solvothermal method. • The framework possesses a new kvh1 topology. • The framework displays formaldehyde and benzaldehyde absorption property. • Conformational analysis was performed to determine the stable linker geometry.« less

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.

New insight into the promoting role of process on the CeO₂-WO₃/TiO₂ catalyst for NO reduction with NH₃ at low-temperature.

PubMed

Zhang, Shule; Zhong, Qin; Shen, Yuge; Zhu, Li; Ding, Jie

2015-06-15

This study aimed at investigating the reason of high catalytic activity for CeO2-WO3/TiO2 catalyst from the aspects of WO3 interaction with other species and the NO oxidation process. Analysis by X-ray diffractometry, photoluminescence spectra, diffuse reflectance UV-visible, X-ray photoelectron spectroscopy, density functional theory calculations, electron paramagnetic resonance spectroscopy, temperature-programmed-desorption of NO and in situ diffuse reflectance infrared transform spectroscopy showed that WO3 could interact with CeO2 to improve the electron gaining capability of CeO2 species. In addition, WO3 species acted as electron donating groups to transfer the electrons to CeO2 species. The two aspects enhanced the formation of reduced CeO2 species to improve the formation of superoxide ions. Furthermore, the Ce species were the active sites for the NO adsorption and the superoxide ions over the catalyst needed oxidizing the adsorbed NO to improve the NO oxidation. This process was responsible for the high catalytic activity of CeO2-WO3/TiO2 catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

Time-resolved x-ray diffraction and Raman studies of the phase transition mechanisms of methane hydrate

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

Hirai, Hisako, E-mail: hirai@sci.ehime-u.ac.jp; Kadobayashi, Hirokazu; Hirao, Naohisa

The mechanisms by which methane hydrate transforms from an sI to sH structure and from an sH to filled-ice Ih structure were examined using time-resolved X-ray diffractometry (XRD) and Raman spectroscopy in conjunction with charge-coupled device camera observation under fixed pressure conditions. The XRD data obtained for the sI–sH transition at 0.8 GPa revealed an inverse correlation between sI and sH, suggesting that the sI structure is replaced by sH. Meanwhile, the Raman analysis demonstrated that although the 12-hedra of sI are retained, the 14-hedra are replaced sequentially by additional 12-hedra, modified 12-hedra, and 20-hedra cages of sH. With themore » sH to filled-ice Ih transition at 1.8 GPa, both the XRD and Raman data showed that this occurs through a sudden collapse of the sH structure and subsequent release of solid and fluid methane that is gradually incorporated into the filled-ice Ih to complete its structure. This therefore represents a typical reconstructive transition mechanism.« less

X-ray characterization of indium during melting

NASA Astrophysics Data System (ADS)

Gondi, P.; Montanari, R.; Costanza, G.

During melting of Indium the structure of solid and liquid phases have been investigated by X-ray diffractometry (XRD) in 1-g conditions. At the melting point T M a re-orientation of crystalline grains occurs in the solid phase. The texture change, unusually rapid for a thermally activated process, is attributed to an abnormal increase of vacancy concentration. This explanation is in agreement with the observed shifts of XRD peaks towards lower angles. As a consequence of the texture change, the lattice planes facing the first formed liquid are (002) and (101) planes, i.e. those planes allocating 1st and 2nd neighbours around a given atom with shell radii very close to the mean distance of nearest neighbours in liquid as obtained from the radial distribution function (RDF). Convective motions in the liquid can be eliminated by repeating the same XRD measurements in μ-g. To get the best experimental conditions it is discussed the possibility to use thin oxide films grown on the external surface of samples as containers during melting. This technique was already successfully tested by present investigators in the experiment ES 311 A-B carried out during the mission SPACELAB-1.

Multivariate Quantification of the Solid State Phase Composition of Co-Amorphous Naproxen-Indomethacin.

PubMed

Beyer, Andreas; Grohganz, Holger; Löbmann, Korbinian; Rades, Thomas; Leopold, Claudia S

2015-10-27

To benefit from the optimized dissolution properties of active pharmaceutical ingredients in their amorphous forms, co-amorphisation as a viable tool to stabilize these amorphous phases is of both academic and industrial interest. Reports dealing with the physical stability and recrystallization behavior of co-amorphous systems are however limited to qualitative evaluations based on the corresponding X-ray powder diffractograms. Therefore, the objective of the study was to develop a quantification model based on X-ray powder diffractometry (XRPD), followed by a multivariate partial least squares regression approach that enables the simultaneous determination of up to four solid state fractions: crystalline naproxen, γ-indomethacin, α-indomethacin as well as co-amorphous naproxen-indomethacin. For this purpose, a calibration set that covers the whole range of possible combinations of the four components was prepared and analyzed by XRPD. In order to test the model performances, leave-one-out cross validation was performed and revealed root mean square errors of validation between 3.11% and 3.45% for the crystalline molar fractions and 5.57% for the co-amorphous molar fraction. In summary, even four solid state phases, involving one co-amorphous phase, can be quantified with this XRPD data-based approach.

DSC, X-ray and FTIR studies of a gemfibrozil/dimethyl-β-cyclodextrin inclusion complex produced by co-grinding.

PubMed

Aigner, Z; Berkesi, O; Farkas, G; Szabó-Révész, P

2012-01-05

The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25°C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil-dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

Ammonia induced precipitation of cobalt hydroxide: observation of turbostratic disorder

NASA Astrophysics Data System (ADS)

Ramesh, T. N.; Rajamathi, Michael; Kamath, P. Vishnu

2003-05-01

Cobalt hydroxide freshly precipitated from aqueous solutions of Co salts using ammonia, is a layered phase having a 9.17 Å interlayer spacing. DIFFaX simulations of the PXRD pattern reveal that it is turbostratically disordered.

Copper-based metal coordination complexes with Voriconazole ligand: Syntheses, structures and antimicrobial properties

NASA Astrophysics Data System (ADS)

Zhao, Yan-Ming; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Ng, Seik Weng

2018-03-01

Three new chiral metal coordination complexes, namely, [Cu(FZ)2(CH3COO)2(H2O)]·2H2O (1), [Cu(FZ)2(NO3)2] (2), and [Cu2(FZ)2 (H2O)8](SO4)2·4H2O (3) [FZ = (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoro-4-pyrimidiny)-1-(1H-1,2,4-triazol-1-yl)-2-butanol) (Voriconazole)] have been obtained by the reaction of Cu(II) salts and the free ligand FZ at room temperature. Complexes 1-3 were structurally characterized by X-ray single-crystal diffraction, IR, UV-vis, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Complex 1 crystallizes in the chiral space group C2, which exhibits a mono-nuclear structure. Both complexes 2 and 3 display a one-dimensional (1D) tape structure, which crystallize in chiral space group P21212 and P212121, respectively. Among these complexes, there exist a variety of hydrogen bonds and stacking interactions, through which a three-dimensional supramolecular architecture will be generated. Compared with the standard (Voriconazole), these Cu-based complexes show the more potent inhibiting efficiency against the species of Candida and Aspergillus. Moreover, among these complexes, complex 1 shows the most excellent efficiency.

In situ hydrothermal syntheses, structures and photoluminescent properties of four novel metal-organic frameworks constructed by lanthanide (Ln=Ce(III), Pr(III), Eu(III)) and Cu(I) metals with flexible dicarboxylate acids and piperazine-based ligands

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

Ay, Burak; Karaca, Serkan; Yildiz, Emel, E-mail: eeyildiz@cu.edu.tr

2016-01-15

Four novel metal-organic frameworks,[Cu{sub 2}Cl{sub 2}(pyrz)]{sub n} (1) and (H{sub 2}pip){sub n}[Ln{sub 2}(pydc){sub 4}(H{sub 2}O){sub 2}]{sub n} (Ln=Ce (2), Pr (3) and Eu (4), H{sub 2}pzdc=2,3-pyrazinedicarboxylic acid, pyrz=pyrazine, H{sub 2}pydc=2,6-pyridinedicarboxylic acid, H{sub 2}pip=piperazine) have been synthesized under hydrothermal conditions and characterized by the elemental analysis, ICP, Far IR (FIR), FT-IR spectra, TGA, single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). Compound 1 is two-dimensional containing Cl-Cu-Cl sites, while the lanthanide complexes contain one-dimensional infinite Ln–O-Ln chains. All the complexes show high thermal stability. The complexes 1–3 exhibit luminescence emission bands at 584, 598 and 614 nm at roommore » temperature when excited at 300 nm. Complex 4 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature. - Graphical abstract: Four novel metal-organic frameworks have been synthesized under hydrothermal conditions. Thermal and luminescent properties of the compounds have been investigated.« less

Three new hydrochlorothiazide cocrystals: Structural analyses and solubility studies

NASA Astrophysics Data System (ADS)

Ranjan, Subham; Devarapalli, Ramesh; Kundu, Sudeshna; Vangala, Venu R.; Ghosh, Animesh; Reddy, C. Malla

2017-04-01

Hydrochlorothiazide (HCT) is a diuretic BCS class IV drug with poor aqueous solubility and low permeability leading to poor oral absorption. The present work explores the cocrystallization technique to enhance the aqueous solubility of HCT. Three new cocrystals of HCT with water soluble coformers phenazine (PHEN), 4-dimethylaminopyridine (DMAP) and picolinamide (PICA) were prepared successfully by solution crystallization method and characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), fourier transform -infraredspectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Structural characterization revealed that the cocrystals with PHEN, DMAP and PICA exists in P21/n, P21/c and P21/n space groups, respectively. The improved solubility of HCT-DMAP (4 fold) and HCT-PHEN (1.4 fold) cocrystals whereas decreased solubility of HCT-PICA (0.5 fold) as compared to the free drug were determined after 4 h in phosphate buffer, pH 7.4, at 25 °C by using shaking flask method. HCT-DMAP showed a significant increase in solubility than all previously reported cocrystals of HCT suggest the role of a coformer. The study demonstrates that the selection of coformer could have pronounced impact on the physicochemical properties of HCT and cocrystallization can be a promising approach to improve aqueous solubility of drugs.

Three new 5-fold interpenetrating diamondoid frameworks constructed by rigid diimidazole and dicarboxylate ligands

NASA Astrophysics Data System (ADS)

Huo, Jianqiang; Yan, Shuai; Li, Haiqiang; Yu, Donghui; Arulsamy, Navamoney

2018-03-01

A series of three-dimensional coordination polymers, namely, [Cd(BIMB)(SCA)]n (1), [M(BIMB)(trans-CHDC)]n (2, M = Cd2+; 3, M = Co2+), where BIMB = 1,4-di(1H-imidazol-1-yl)benzene, SCA2- = succinate dianion, CHDC2- = cyclohexane-1,4-dicarboxylate dianion) are synthesized hydro/solvatothermal methods. The products are characterized by elemental analysis and single-crystal X-ray diffraction data. Both the dianion and BIMB bridge different pairs of the metal ions, the three complexes are polymeric and their three-dimensional topology feature a diamond-like metal-organic framework (MOF). Owing to the length of the two bridging ligands, moderate size voids are formed in the diamondoid networks. However, the voids are filled by mutual interpenetration of four independent equivalent frameworks in a 5-fold interpenetrating architecture, and there is no sufficient void volume available for any guest molecules. The phase purity and thermal stability of the compounds are verified by powder X-ray diffraction (PXRD) and thermogravimetric (TG) data. The solid-state fluorescence spectra for the 3d10 Cd2+ MOF's 1 and 2 reveal significant enhancement in their emission intensities in comparison to the non-metallated BIMB. The enhanced emission is attributed to perturbation of intra-ligand emission states due to Cd2+ coordination.

Synthesis, crystal structure, and luminescent properties of two coordination polymers based on 1,4-phenylenediacetic acid

NASA Astrophysics Data System (ADS)

Zhang, Meili; Ren, Yixia; Ma, Zhenzhen; Qiao, Lei

2017-06-01

Two coordination polymers, [Zn(pda)(bib)]n (1) and [Cd(pda)0.5(bib)Cl]n (2)]. (H2pda = 1,4-phenylenediacetic acid, bib = 1,2-bis(imidazol-1-ylmethyl)benzene), have been synthesized by using Zn(II)/Cd(II) salts with two flexible ligands pda and bib under hydrothermal conditions. Their structures have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography and powder X-ray diffraction (PXRD) analysis. Due to the coordination geometry around the metal ions and the diverse coordination modes of the flexible ligands, the obtained complex show diverse structures. In the structure of 1, a pair of bib ligands connect two Zn(II) atoms give rise a 22-membered ring, which is further extended by pda ligands in bidentate coordination mode leading a ring-containing 2D layer. In 2, bib ligands join [Cd2Cl2]2+ dimmers generate 1D polymeric ribbon, the pda ligands further extend such ribbon forming a 2D layer network containing rectangular windows, which discovers the effect of the central metal ions on the formation of metal-organic frameworks. In additional, luminescent properties of two complexes have also been studied, they could be potential fluorescence materials.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

NASA Astrophysics Data System (ADS)

Kumar, Danith; Yadav, L. S. Reddy; Lingaraju, K.; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.; Naika, H. Raja; Chikkahanumantharayappa, Nagaraju, G.

2015-06-01

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm-1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV -Vis spectrum was found to be in the range 5.40-5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

Synthesis, characterization and experimental investigation of Cu-BTC as CO2 adsorbent from flue gas.

PubMed

Xie, Jiangkun; Yan, Naiqiang; Qu, Zan; Yang, Shijian

2012-01-01

Porous Cu-BTC material was synthesized by the solvothermal method. Powder X-ray diffraction (PXRD) was used to test the phase purity of the synthesized material and investigate its structural stability under the influence of flue gas components. The thermal stability of the material was determined through thermal gravimetric (TG) analysis. Scanning electron microscopy (SEM) was employed to study the microstructure of the material. Cu-BTC was demonstrated not only to have high CO2 adsorption capacity but also good selectivity of CO2 over N2 by means of packed bed tests. The adsorption capacity of Cu-BTC for CO2 was about 69 mL/g at 22 degrees C. The influence of the main flue gas components on the CO2 capacity of the material were discussed as well.

Swollen poly(dimethylsiloxane) (PDMS) as a template for inorganic morphologies.

PubMed

Brennan, Daniel P; Dobley, Arthur; Sideris, Paul J; Oliver, Scott R J

2005-12-06

We report a series of silica, titania, and zirconia microstructures synthesized within swollen poly(dimethylsiloxane) (PDMS). Voids created by solvent-swelling the polymer are used to template the product. The inorganic morphologies range from spheres to networks, depending upon the nature of the polymer, its degree of swelling, and the synthetic conditions. Organic solvents as well as pure metal alkoxide liquids have been used to swell the polymer. Once the alkoxide precursor is inside the swollen polymer, water is introduced to bring about hydrolysis and condensation polymerization. The product is a textured metal oxide within a PDMS matrix. Scanning electron microscopy (SEM), optical microscopy, nuclear magnetic resonance (NMR), and powder X-ray diffraction (PXRD) were used to characterize the products. Microstructures formed in this manner have potential use as an inexpensive route to catalysts, fillers, capsules, or membranes for separations.

Anomalous magnetoelastic behaviour near morphotropic phase boundary in ferromagnetic Tb 1-xNd xCo 2 system

DOE PAGES

Murtaza, Adil; Yang, Sen; Zhou, Chao; ...

2016-08-04

In this study, we report a morphotropic phase boundary (MPB) involved ferromagnetic system Tb 1-xNd xCo 2 and reveal the corresponding structural and magnetoelastic properties of this system. With high resolution synchrotron X-ray diffractometry, the crystal structure of the TbCo 2-rich side is detected to be rhombohedral and that of NdCo 2-rich side is tetragonal below their respective Curie temperatures TC. The MPB composition Tb 0.35Nd 0.65Co 2 corresponds to the coexistence of the rhombohedral phase (R-phase) and tetragonal phase ( T-phase). Contrary to previously reported MPB involved ferromagnetic systems, the MPB composition of Tb 0.35Nd 0.65Co 2 shows minimummore » magnetization which can be understood as compensation of sublattice moments between the R-phase and the T-phase. Furthermore, magnetostriction of Tb 1-xNd xCo 2 decreases with increasing Nd concentration until x = 0.8 and then increases in the negative direction with further increasing Nd concentration; the optimum point for magnetoelastic properties lies towards the rhombohedral phase. Finally, our work not only shows an anomalous type of ferromagnetic MPB but also provides an effective way to design functional materials.« less

50 MeV, Li{sup 3+} - ion irradiation effect on magnetic ordering of Y{sup 3+} - substituted yttrium iron garnet

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

Sharma, P. U.; Zankat, K. B.; Dolia, S. N.

2016-05-06

This communication presents the effect of non-magnetic Y{sup 3+} ions substitution for magnetic Fe{sup 3+} ions and 50 MeV, Li{sup 3+} ion irradiation (fluence: 5 × 10{sup 13} ions/cm{sup 2}) on magnetic ordering and Neel temperature of Y{sub 3+x}Fe{sub 5-x}O{sub 12} (x = 0.0, 0.2, 0.4 and 0.6) garnet system, studied by means of X-ray powder diffractometry and thermal variation of low field (0.5 Oe) ac susceptibility measurements. The un-irradiated compositions exhibit normal ferrimagnetic behavior with decrease in transition temperature (T{sub N}) on increasing Y{sup 3+}-concentration (x). The irradiated counterparts are characterized by tailing effect indicative of non-uniform effect of irradiationmore » and lower value of T{sub N}. The results have been discussed based on the weakening of magnetic exchange interactions and cumulative effect of redistribution of cations and fractional creation of localized paramagnetic centers resulting from swift heavy ion irradiation. The Neel temperatures and exchange integrals have been calculated theoretically.« less

Preparation of oridonin-loaded solid lipid nanoparticles and studies on them in vitro and in vivo

NASA Astrophysics Data System (ADS)

Zhang, Dianrui; Tan, Tianwei; Gao, Lei

2006-12-01

Oridonin, a lipophilic Chinese medicine, has very low oral bioavailability due to its poor solubility. Solid lipid nanoparticle (SLN) delivery systems of oridonin have been formed using stearic acid, soybean lecithin and pluronic F68 in our studies to overcome this problem. Emulsion evaporation-solidification at low temperature was used to prepare SLN dispersions. The particle size and morphology were examined by transmission electron microscopy (TEM), and the zeta potential was measured by a television micro-electrophoresis apparatus. Process and formulation variables have been studied and optimized on the basis of entrapment efficiency. Differential scanning calorimetry (DSC) and powder x-ray diffraction (PXRD) studies were performed to characterize the state of the drug. In vitro release studies were performed in phosphate-buffer solution (PBS) (pH 7.4). The tissue distribution in mice and the pharmacokinetics in rabbits were studied to evaluate the tissue targeted property of SLNs. Stable SLN formulations of oridonin having a mean size range of 15-35 nm and mean zeta potential -45.07 mV were developed. More than 40% oridonin was entrapped in SLNs. DSC and PXRD analysis showed that oridonin is dispersed in SLNs in an amorphous state. The release pattern of the drug was analysed and found to follow the Higuchi equations. In vivo studies demonstrated that oridonin-loaded SLNs obviously increased the concentration of oridonin in liver, lung and spleen, while its distribution in heart and kidney decreased.

Monitoring ibuprofen-nicotinamide cocrystal formation during solvent free continuous cocrystallization (SFCC) using near infrared spectroscopy as a PAT tool.

PubMed

Kelly, A L; Gough, T; Dhumal, R S; Halsey, S A; Paradkar, A

2012-04-15

The purpose of this work was to explore NIR spectroscopy as a PAT tool to monitor the formation of ibuprofen and nicotinamide cocrystals during extrusion based solvent free continuous cocrystallization (SFCC). Drug and co-former were gravimetrically fed into a heated co-rotating twin screw extruder to form cocrystals. Real-time process monitoring was performed using a high temperature NIR probe in the extruder die to assess cocrystal content and subsequently compared to off-line powder X-ray diffraction measurements. The effect of processing variables, such as temperature and mixing intensity, on the extent of cocrystal formation was investigated. NIR spectroscopy was sensitive to cocrystal formation with the appearance of new peaks and peak shifts, particularly in the 4800-5200 cm(-1) wave-number region. PXRD confirmed an increased conversion of the mixture into cocrystal with increase in barrel temperature and screw mixing intensity. A decrease in screw rotation speed also provided improved cocrystal yield due to the material experiencing longer residence times within the process. A partial least squares analysis in this region of NIR spectrum correlated well with PXRD data, providing a best fit with cocrystal conversion when a limited range of process conditions were considered, for example a single set temperature. The study suggests that NIR spectroscopy could be used to monitor cocrystal purity on an industrial scale using this continuous, solvent-free process. Copyright © 2011 Elsevier B.V. All rights reserved.

Quantifying Morphological Features of α-U3O8 with Image Analysis for Nuclear Forensics.

PubMed

Olsen, Adam M; Richards, Bryony; Schwerdt, Ian; Heffernan, Sean; Lusk, Robert; Smith, Braxton; Jurrus, Elizabeth; Ruggiero, Christy; McDonald, Luther W

2017-03-07

Morphological changes in U 3 O 8 based on calcination temperature have been quantified enabling a morphological feature to serve as a signature of processing history in nuclear forensics. Five separate calcination temperatures were used to synthesize α-U 3 O 8 , and each sample was characterized using powder X-ray diffraction (p-XRD) and scanning electron microscopy (SEM). The p-XRD spectra were used to evaluate the purity of the synthesized U-oxide; the morphological analysis for materials (MAMA) software was utilized to quantitatively characterize the particle shape and size as indicated by the SEM images. Analysis comparing the particle attributes, such as particle area at each of the temperatures, was completed using the Kolmogorov-Smirnov two sample test (K-S test). These results illustrate a distinct statistical difference between each calcination temperature. To provide a framework for forensic analysis of an unknown sample, the sample distributions at each temperature were compared to randomly selected distributions (100, 250, 500, and 750 particles) from each synthesized temperature to determine if they were statistically different. It was found that 750 particles were required to differentiate between all of the synthesized temperatures with a confidence interval of 99.0%. Results from this study provide the first quantitative morphological study of U-oxides, and reveals the potential strength of morphological particle analysis in nuclear forensics by providing a framework for a more rapid characterization of interdicted uranium oxide samples.

Influence of Grain Refinement on Microstructure and Mechanical Properties of Tungsten Carbide/Zirconia Nanocomposites

NASA Astrophysics Data System (ADS)

Nasser, Ali; Kassem, Mohamed A.; Elsayed, Ayman; Gepreel, Mohamed A.; Moniem, Ahmed A.

2016-11-01

WC-W2C/ZrO2 nanocomposites were synthesized by pressure-less sintering (PS) and spark plasma sintering (SPS) of tungsten carbide/yttria-stabilized tetragonal zirconia, WC/TZ-3Y. Prior to sintering, WC/TZ-3Y powders were totally ball-milled for 20 and 120 h to obtain targeted nano (N) and nano-nano (N-N) structures, indicated by transmission electron microscopy and powder x-ray diffraction (PXRD). The milled powders were processed via PS at temperatures of 1773 and 1973 K for 70 min and SPS at 1773 K for 10 min. PXRD as well as SEM-EDS indicated the formation of WC-W2C/ZrO2 composites after sintering. The mechanical properties were characterized via Vicker microhardness and nanoindentation techniques indicating enhancements for sufficiently consolidated composites with high W2C content. The effects of reducing particle sizes on phase transformation, microstructure and mechanical properties are reported. In general, the composites based on the N structure showed higher microhardness than those for N-N structure, except for the samples PS-sintered at 1773 K. For instance, after SPS at 1773 K, the N structure showed a microhardness of 18.24 GPa. Nanoindentation measurements revealed that nanoscale hardness up to 22.33 and 25.34 GPa and modulus of elasticity up to 340 and 560 GPa can be obtained for WC-W2C/ZrO2 nanocomposites synthesized by the low-cost PS at 1973 K and by SPS at 1773 K, respectively.

Preparation and characterization of azithromycin--Aerosil 200 solid dispersions with enhanced physical stability.

PubMed

Li, Xuechao; Peng, Huanhuan; Tian, Bin; Gou, Jingxin; Yao, Qing; Tao, Xiaoguang; He, Haibing; Zhang, Yu; Tang, Xing; Cai, Cuifang

2015-01-01

The main purpose of this study was to investigate the feasibility of azithromycin (AZI)--Aerosil 200 solid dispersions specifically with high stability under accelerated condition (40 °C/75% RH). Ball milling (BM) and hot-melt extrusion (HME) were used to prepare AZI solid dispersions. The physical properties of solid dispersions were evaluated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). For solid dispersions prepared with both methods, no crystalline of AZI was detected (except for AZI: Aerosil 200=75:25) by DSC or PXRD, indicating the amorphous state of AZI in solid dispersions. The FT-IR results demonstrated the loss of crystallization water and the formation of hydrogen bonds between Aerosil 200 and AZI during the preparation of solid dispersions. After 4 weeks storage under accelerated condition, the degree of crystallinity of AZI increased in solid dispersions prepared by BM, whereas for solid dispersions containing AZI, Aerosil 200 and glyceryl behenate (GB) prepared by HME, no crystalline of AZI was identified. This high stability can be attributed to the hydrophobic properties of GB and the presence of hydrogen bonds. Based on the above results, it is inferred the protection of hydrogen bonds between AZI and Aerosil 200 formed during preparation process effectively inhibited the recrystallization of AZI and improved the physical stability of amorphous AZI in the presence of Aerosil 200. Copyright © 2015 Elsevier B.V. All rights reserved.

Selective removal of monoterpenes from bergamot oil by inclusion in deoxycholic acid.

PubMed

Fantin, Giancarlo; Fogagnolo, Marco; Maietti, Silvia; Rossetti, Stefano

2010-05-12

A new approach for removing monoterpenes (MTs) from bergamot oil by selective inclusion in deoxycholic acid (DCA) is proposed. The inclusion process is very efficient, the included fraction being composed mainly of limonene (71.7%) and gamma-terpinene (19.8%). On the other hand, the deterpenated bergamot oil fraction showed for the linalool and linalyl acetate derivatives significant increases from 16.6 and 21.4% to 18.3 and 42.2%, respectively. The major advantages of this methodology are its simplicity, the mild conditions employed, and the quantitative recovery of both host (DCA) and guest (monoterpenes) compounds. Differential scanning calorimetry (DSC), thermal gravimetry (TG), powder X-ray diffractometry (XRPD), infrared spectroscopy (IR), and proton magnetic resonance ((1)H NMR) analysis were used to investigate and characterize the inclusion compounds.

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.

Mechanistic Insight into Caffeine-Oxalic Cocrystal Dissociation in Formulations: Role of Excipients.

PubMed

Duggirala, Naga Kiran; Vyas, Amber; Krzyzaniak, Joseph F; Arora, Kapildev K; Suryanarayanan, Raj

2017-11-06

Caffeine-oxalic acid cocrystal, widely reported to be stable under high humidity, dissociated in the presence of numerous pharmaceutical excipients. In cocrystal-excipient binary systems, the water mediated dissociation reaction occurred under pharmaceutically relevant storage conditions. Powder X-ray diffractometry was used to identify the dissociated products obtained as a consequence of coformer-excipient interaction. The proposed cocrystal dissociation mechanism involved water sorption, dissolution of cocrystal and excipient in the sorbed water, proton transfer from oxalic acid to the excipient, and formation of metal salts and caffeine hydrate. In compressed tablets with magnesium stearate, the cocrystal dissociation was readily discerned from the appearance of peaks attributable to caffeine hydrate and stearic acid. Neutral excipients provide an avenue to circumvent the risk of water mediated cocrystal dissociation.

Impact of plant matrix polysaccharides on cellulose produced by surface-tethered cellulose synthases.

PubMed

Basu, Snehasish; Omadjela, Okako; Zimmer, Jochen; Catchmark, Jeffrey M

2017-04-15

Surface immobilized BcsA-B cellulose synthases synthesize crystalline cellulose II under in vitro conditions and were used to explore the interaction between cellulose and hemicelluloses and pectin. The morphology of the cellulose microfibrils changed in the presence of xyloglucan and glucomannan, while pectin did not significantly impact morphology. X-ray diffractometry and FT-IR spectroscopy indicated that crystal size and crystallinity were significantly affected by xyloglucan and glucomannan but not altered by pectin. Glucomannan had the most significant impact on the structure of cellulose and inhibits crystallization. The presence of xyloglucan and glucomannan prevents the proper assembly of cellulose microfibrils and changes the crystalline properties of cellulose II in in vitro conditions, but did not have any impact on cellulose allomorph. Copyright © 2017 Elsevier Ltd. All rights reserved.

Geology and geochemistry of the Arctic prospect, Ambler District, Alaska

NASA Astrophysics Data System (ADS)

Schmidt, J. M.

The Arctic volcanogenic massive sulfide prospect is the largest known (40 million ton) deposit hosted by the low greenschist grade, latest Devonian Ambler Sequence of bimodal, basaltic and rhyolitic volcanic and volcanoclastic rocks, pelitic, graphitic and calcareous metasediments. Detailed field mapping, core logging, petrography, X-ray diffractometry, electron microprobe analyses and whole-rock major element analyses of hydrothermally altered rocks were used to determine the emplacement history and setting of sulfide deposition. Low greenschist grade metamorphism was essentially isochemical on a macroscopic scale, and preserved volcanic compositions, the major element chemistry of alteration and the compositions of individual metamorphic, alteration and relict igneous minerals. Mineralization at Arctic was formed along a synvolcanic fault in a tectonically and volcanically active basin within a rifted continental margin, possibly related to an actively spreading oceanic rift.

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.

In-situ determination of austenite and martensite formation in 13Cr6Ni2Mo supermartensitic stainless steel

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

Bojack, A., E-mail: a.bojack@tudelft.nl; Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft; Zhao, L.

2012-09-15

In-situ analysis of the phase transformations in a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was carried out using a thermo-magnetic technique, dilatometry and high temperature X-ray diffractometry (HT-XRD). A combination of the results obtained by the three applied techniques gives a valuable insight in the phase transformations during the austenitization treatment, including subsequent cooling, of the 13Cr6Ni2Mo supermartensitic stainless steel, where the magnetic technique offers a high accuracy in monitoring the austenite fraction. It was found by dilatometry that the austenite formation during heating takes place in two stages, most likely caused by partitioning of Ni into austenite. The in-situ evolutionmore » of the austenite fraction is monitored by high-temperature XRD and dilatometry. The progress of martensite formation during cooling was described with a Koistinen-Marburger relation for the results obtained from the magnetic and dilatometer experiments. Enhanced martensite formation at the sample surface was detected by X-ray diffraction, which is assumed to be due to relaxation of transformation stresses at the sample surface. Due to the high alloy content and high thermodynamic stability of austenite at room temperature, 4 vol.% of austenite was found to be stable at room temperature after the austenitization treatment. - Highlights: Black-Right-Pointing-Pointer We in-situ analyzed phase transformations and fractions of a 13Cr6Ni2Mo SMSS. Black-Right-Pointing-Pointer Higher accuracy of the austenite fraction was obtained from magnetic technique. Black-Right-Pointing-Pointer Austenite formation during heating takes place in two stages. Black-Right-Pointing-Pointer Enhanced martensite formation at the sample surface detected by X-ray diffraction.« less

Triphenyltin derivatives of sulfanylcarboxylic esters.

PubMed

Casas, José S; Couce, María D; Sánchez, Agustín; Seoane, Rafael; Sordo, José; Perez-Estévez, Antonio; Vázquez-López, Ezequiel

2018-03-01

The reaction of 3-(aryl)-2-sulfanylpropenoic acids [H 2 xspa; x: p=3-phenyl-, f=3-(2-furyl)-, t=3-(2-thienyl)-] with methanol or ethanol gave the corresponding methyl (Hxspme) or ethyl (Hxspee) esters. The reaction of these esters (HL) with triphenyltin(IV) hydroxide gave compounds of the type [SnPh 3 L], which were isolated and characterized as solids by elemental analysis, IR spectroscopy and mass spectrometry and in solution by multinuclear ( 1 H, 13 C and 119 Sn) NMR spectroscopy. The structures of [SnPh 3 (pspme)], [SnPh 3 (fspme)] and [SnPh 3 (fspee)] were determined by X-ray diffractometry and the antimicrobial activity against E. coli, S. aureus, B. subtilis, P. aeruginosa, Resistant P. aeruginosa (a strain resistant to 'carbapenem'), and C. albicans was tested and the in vitro cytotoxic activity against the HeLa-229, A2780 and A2780cis cell lines was determined for all compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Purification of uranothorite solid solutions from polyphase systems

NASA Astrophysics Data System (ADS)

Clavier, Nicolas; Szenknect, Stéphanie; Costin, Dan Tiberiu; Mesbah, Adel; Ravaux, Johann; Poinssot, Christophe; Dacheux, Nicolas

2013-10-01

The mineral coffinite, nominally USiO4, and associated Th1-xUxSiO4 uranothorite solid solutions are of great interest from a geochemical point of view and in the case of the direct storage of spent nuclear fuels. Nevertheless, they clearly exhibit a lack in the evaluation of their thermodynamic data, mainly because of the difficulties linked with their preparation as pure phases. This paper thus presents physical and chemical methods aiming to separate uranothorite solid solutions from oxide additional phases such as amorphous SiO2 and nanometric crystallized Th1-yUyO2. The repetition of centrifugation steps envisaged in first place was rapidly dropped due to poor recovery yields, to the benefit of successive washings in acid then basic media. Under both static and dynamic flow rates (i.e. low or high rate of leachate renewal), ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectroscopy) analyses revealed the systematic elimination of Th1-yUyO2 in acid media and of SiO2 in basic media. Nevertheless, two successive steps were always needed to reach pure samples. On this basis, a first cycle performed in static conditions was chosen to eliminate the major part of the accessory phases while a second one, in dynamic conditions, allowed the elimination of the residual impurities. The complete purification of the samples was finally evidenced through the characterization of the samples by the means of PXRD (Powder X-Ray Diffraction), SEM (Scanning Electron Microscopy) observations and X-EDS (X-Ray Energy Dispersive Spectroscopy) analyses.

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

Copper and manganese complexes based on 1,4-naphthalene dicarboxylic acid ligand and its derivative: Syntheses, crystal structures, and magnetic properties

NASA Astrophysics Data System (ADS)

Xing, Yubo; Liu, Yuqi; Xue, Xiaofei; Wang, Xinying; Li, Wei

2018-02-01

Three new metal-organic coordination polymers, {[Mn2(1,4-NDC)2 (C2H5OH) (DMF) (H2O)]·CH3OH}n(1), {[Mn(III)(1,4-NDC)(C2H5O)][Mn(II)(1,4-NDC)(DMF)(H2O)]}n(2) and {[Cu2(C13H9O4)4(H2O)2]}n(3) based on1,4-H2NDC and its derivative were hydrothermally synthesized (1,4-H2NDC = 1,4-naphthalene-dicarboxylic acid, C13H10O4 = 4-methyl formate-1-naphthalenecarboxylic acid), and characterized by techniques of single crystal X-ray diffraction, infrared spectra (IR), elemental analysis, powder X-ray diffraction(PXRD) and variable-temperature magnetic susceptibility measurements. X-ray crystal structure analyses reveal that complexes 1 and 2 show a same 3,5-connected fsc 3D topology network with the Schlȁfli symbol of {4·6·8}{4·66·83}. But, the valence of some Mn atom in complex 2 take place transition from the +II oxidation state to the +III oxidation state, which may be the effect of the different solvent ratio. In complex 3, the Cu⋯Cu distance of 2.620(13) Å is significantly shorter than the sum of the van der Waals radii of Cu (1.40 Å), resulting in a strong ferromagnetic interaction between the Cu(II) centers. Furthermore, the temperature-dependent magnetic susceptibility measurements exhibit overall antiferromagnetic interactions between manganese ions for complexes 1 and 2, and a strong ferromagnetic interaction between the Cu(II) centers for complex 3.

Electron irradiation induced effects on the physico-chemical properties of L-Arginine Maleate Dihydrate (LAMD) single crystals

NASA Astrophysics Data System (ADS)

Thomas, Prince; Dhole, S. D.; Joseph, Ginson P.

2018-07-01

Single crystals of L-Arginine Maleate Dihydrate (LAMD) have been synthesized by slow solvent evaporation technique and irradiated with 6 MeV electrons at fluences of 0.5 ×1015e /cm2 , 1.0 ×1015e /cm2 and 1.5 ×1015e /cm2 . The Powder X-ray Diffraction (PXRD) studies showed that the intensity of the diffraction peaks of the Electron Beam (EB) irradiated crystals decreases with irradiation fluence. The electron irradiation induced effects on the optical parameters such as cut-off wavelength, band gap, Urbach energy and refractive index have been studied and the results are tabulated. The electronic parameters such as valence electron plasma energy, ℏωp , Penn gap, Ep , Fermi energy, EF and Electronic polarizability, α for pure and irradiated LAMD crystals are calculated. The electrical and thermal properties of the pure and irradiated LAMD crystals are also investigated.

Pyrolytic synthesis and luminescence of porous lanthanide Eu-MOF.

PubMed

Jin, Guangya; Liu, Zhijian; Sun, Hongfa; Tian, Zhiyong

2016-02-01

A lanthanide metal coordination polymer [Eu2(BDC)3(DMSO)(H2O)] was synthesized by the reaction of europium oxide with benzene-1,3-dicarboxylic acid (H2BDC) in a mixed solution of dimethyl sulfoxide (DMSO) and water under hydrothermal conditions. The crystal structure of Eu2(BDC)3(DMSO)(H2O) was characterized by X-ray diffraction (XRD). Thermo-gravimetric analysis of Eu2(BDC)3(DMSO)(H2O) indicated that coordinated DMSO and H2O molecules could be removed to create Eu2(BDC)3(DMSO)(H2O)-py with permanent microporosity, which was also verified by powder XRD (PXRD) and elemental analysis. Both Eu2(BDC)3(DMSO)(H2O) and Eu2(BDC)3(DMSO)(H2O)-py showed mainly Eu-based luminescence and had characteristic emissions in the range 550-700 nm. Copyright © 2015 John Wiley & Sons, Ltd.

A Simple Approach to Enhance the Water Stability of a Metal-Organic Framework.

PubMed

Shih, Yung-Han; Kuo, Yu-Ching; Lirio, Stephen; Wang, Kun-Yun; Lin, Chia-Her; Huang, Hsi-Ya

2017-01-01

A facile method to improve the feasibility of water-unstable metal-organic frameworks in an aqueous environment has been developed that involves imbedding in a polymer monolith. The effect of compartment type during polymerization plays a significant role in maintaining the crystalline structure and thermal stability of the MOFs, which was confirmed by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA), respectively. The MOF-polymer composite prepared in a narrow compartment (column, ID 0.8 mm) has better thermal and chemical stability than that prepared in a broad compartment (vial, ID 7 mm). The developed MOF-polymer composite was applied as an adsorbent in solid-phase microextraction of nine non-steroidal anti-inflammatory drugs (NSAIDs) and could be used for extraction more than 30 times, demonstrating that the proposed approach has potential for industrial applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

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

Kumar, Danith; Chikkahanumantharayappa; Yadav, L. S. Reddy

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emissionmore » at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.« less

Physicochemical and mechanical properties of paracetamol cocrystal with 5-nitroisophthalic acid.

PubMed

Hiendrawan, Stevanus; Veriansyah, Bambang; Widjojokusumo, Edward; Soewandhi, Sundani Nurono; Wikarsa, Saleh; Tjandrawinata, Raymond R

2016-01-30

We report novel pharmaceutical cocrystal of a popular antipyretic drug paracetamol (PCA) with coformer 5-nitroisophhthalic acid (5NIP) to improve its tabletability. The cocrystal (PCA-5NIP at molar ratio of 1:1) was synthesized by solvent evaporation technique using methanol as solvent. The physicochemical properties of cocrystal were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), fourier transform infrared spectroscopy (FTIR), hot stage polarized microscopy (HSPM) and scanning electron microscopy (SEM). Stability of the cocrystal was assessed by storing them at 40°C/75% RH for one month. Compared to PCA, the cocrystal displayed superior tableting performance. PCA-5NIP cocrystal showed a similar dissolution profile as compared to PCA and exhibited good stability. This study showed the utility of PCA-5NIP cocrystal for improving mechanical properties of PCA. Copyright © 2015 Elsevier B.V. All rights reserved.

Terahertz spectra of L-phenylalanine and its monohydrate

NASA Astrophysics Data System (ADS)

Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

2017-05-01

The low-frequency vibrational property of L-phenylalanine (L-Phe) and L-phenylalanine monohydrate (L-Phe·H2O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5 THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of L-Phe and L-Phe·H2O and the results agree well with the experimental observations. The study indicates that the characterized features of L-Phe mainly originate from the collective vibration of molecules. And the characterized features of L-Phe·H2O mainly come from hydrogen bond interactions between L-Phe and water molecules. L-Phe and L-Phe·H2O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations.

Recovery of metals from simulant spent lithium-ion battery as organophosphonate coordination polymers in aqueous media.

PubMed

Perez, Emilie; Andre, Marie-Laure; Navarro Amador, Ricardo; Hyvrard, François; Borrini, Julien; Carboni, Michaël; Meyer, Daniel

2016-11-05

An innovative approach is proposed for the recycling of metals from a simulant lithium-ion battery (LIBs) waste aqueous solution. Phosphonate organic linkers are introduced as precipitating agents to selectively react with the metals to form coordination polymers from an aqueous solution containing Ni, Mn and Co in a hydrothermal process. The supernatant is analyzed by ICP-AES to quantify the efficiency and the selectivity of the precipitation and the materials are characterized by Scanning Electron Microscopy (SEM), Powder X-Ray Diffraction (PXRD), Thermogravimetric Analyses (TGA) and nitrogen gas sorption (BET). Conditions have been achieved to selectively precipitate Manganese or Manganese/Cobalt from this solution with a high efficiency. This work describes a novel method to obtain potentially valuable coordination polymers from a waste metal solution that can be generalized on any waste solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Design and construction of porous metal-organic frameworks based on flexible BPH pillars

NASA Astrophysics Data System (ADS)

Hao, Xiang-Rong; Yang, Guang-sheng; Shao, Kui-Zhan; Su, Zhong-Min; Yuan, Gang; Wang, Xin-Long

2013-02-01

Three metal-organic frameworks (MOFs), [Co2(BPDC)2(4-BPH)·3DMF]n (1), [Cd2(BPDC)2(4-BPH)2·2DMF]n (2) and [Ni2(BDC)2(3-BPH)2 (H2O)·4DMF]n (3) (H2BPDC=biphenyl-4,4'-dicarboxylic acid, H2BDC=terephthalic acid, BPH=bis(pyridinylethylidene)hydrazine and DMF=N,N'-dimethylformamide), have been solvothermally synthesized based on the insertion of heterogeneous BPH pillars. Framework 1 has "single-pillared" MOF-5-like motif with inner cage diameters of up to 18.6 Å. Framework 2 has "double pillared" MOF-5-like motif with cage diameters of 19.2 Å while 3 has "double pillared" 8-connected framework with channel diameters of 11.0 Å. Powder X-ray diffraction (PXRD) shows that 3 is a dynamic porous framework.

Synthesis, characterisation and anion exchange properties of copper, magnesium, zinc and nickel hydroxy nitrates

NASA Astrophysics Data System (ADS)

Biswick, Timothy; Jones, William; Pacuła, Aleksandra; Serwicka, Ewa

2006-01-01

Anion exchange reactions of four structurally related hydroxy salts, Cu 2(OH) 3NO 3, Mg 2(OH) 3NO 3, Ni 2(OH) 3NO 3 and Zn 3(OH) 4(NO 3) 2 are compared and trends rationalised in terms of the strength of the covalent bond between the nitrate group and the matrix cation. Powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis are used to characterise the materials. Replacement of the nitrate anions in the zinc and copper salts with benzoate anions is possible although exchange of the zinc salt is accompanied by modification of the layer structure from one where zinc is exclusively six-fold coordinated to a structure where there is both six- and four-fold zinc coordination. Magnesium and nickel hydroxy nitrates, on the other hand, hydrolyse to their respective metal hydroxides.

Controlled delivery of a hydrophilic drug from a biodegradable microsphere system by supercritical anti-solvent precipitation technique.

PubMed

Lee, S; Kim, M S; Kim, J S; Park, H J; Woo, J S; Lee, B C; Hwang, S J

2006-11-01

The purpose of this study was to prepare microspheres loaded with hydrophilic drug, bupivacaine HCl using poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). Microspheres were prepared with varying the PLGA/PLLA ratio with two different levels of bupivacaine HCl (5 and 10%) using a supercritical anti-solvent (SAS) technique. Microspheres ranging from 4-10 microm in geometric mean diameter could be prepared, with high loading efficiency. Powder X-ray diffraction (PXRD) revealed that bupivacaine HCl retained its crystalline state within the polymer and was present as a dispersion within the polymer phase after SAS processing. The release of bupivacaine HCl from biodegradable polymer microspheres was rapid up to 4 h, thereafter bupivacaine HCl was continuously and slowly released for at least 7 days according to the PLGA/PLLA ratio and the molecular weight of PLLA.

Synthesis of thoria nano-particles at low temperature through base electrogeneration on steel 316L surface: Effect of current density

NASA Astrophysics Data System (ADS)

Yousefi, Taher; Torab-Mostaedi, Meisam; Mobtaker, Hossein Ghasemi; Keshtkar, Ali Reza

2016-10-01

The strategy developed in this study, offers significant advantages (simplicity and cleanness of method and also a product purity and new morphology of the product) over the conventional routes for the synthesis of ThO2 nanostructure. The effect of current density on morphology was studied. The synthesized powder was characterized by means of Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM, Phillips EM 2085) Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared (FT-IR) spectroscopy. The results show that the current density has a great effect on the morphology of the samples. The average size of the particles decreases as the applied current density increases and the average size of the samples decreases from 50 to 15 nm when the current density increases from 2 to 5 mA cm-2.

Structure of H2Ti3O7 and its evolution during sodium insertion as anode for Na ion batteries.

PubMed

Eguía-Barrio, Aitor; Castillo-Martínez, Elizabeth; Zarrabeitia, Maider; Muñoz-Márquez, Miguel A; Casas-Cabanas, Montse; Rojo, Teófilo

2015-03-14

H2Ti3O7 was prepared as a single phase material by ionic exchange from Na2Ti3O7. The complete ionic exchange was confirmed by (1)H and (23)Na solid state Nuclear Magnetic Resonance (NMR). The atomic positions of H2Ti3O7 were obtained from the Rietveld refinement of powder X-ray diffraction (PXRD) and neutron diffraction experimental data, the latter collected at two different wavelengths to precisely determine the hydrogen atomic positions in the structure. All H(+) cations are hydrogen bonded to two adjacent [Ti3O7](2-) layers leading to the gliding of the layers and lattice centring with respect to the parent Na2Ti3O7. In contrast with a previous report where protons were located in two different positions of H2Ti3O7, 3 types of proton positions were found. Two of the three types of proton are bonded to the only oxygen linked to a single titanium atom forming an H-O-H angle close to that of the water molecule. H2Ti3O7 is able to electrochemically insert Na(+). The electrochemical insertion of sodium into H2Ti3O7 starts with a solid solution regime of the C-centred phase. Then, between 0.6 and 1.2 inserted Na(+) the reaction proceeds through a two phase reaction and a plateau at 1.3 V vs. Na(+)/Na is observed in the voltage-composition curve. The second phase resembles the primitive Na2Ti3O7 cell as detected by in situ PXRD. Upon oxidation, from 0.9 to 2.2 V, the PXRD pattern remains mostly unchanged probably due to H(+) removal instead of Na(+), with the capacity quickly fading upon cycling. Conditioning H2Ti3O7 for two cycles at 0.9-2.2 V before cycling in the 0.05-1.6 V range yields similar specific capacity and better retention than the original Na2Ti3O7 in the same voltage range.

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.

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.

Mineralogical characterization of Greda clays and monitoring of their phase transformations on thermal treatment

NASA Astrophysics Data System (ADS)

Panduro, E. Chavez; Cabrejos, J. Bravo

2010-01-01

The mineralogical characterization of two clay samples from the Central Andean Region of Peru, denominated White Greda and Red Greda, is reported. These clays contain the clay minerals mica and illite respectively. Both clays were treated thermally in an oxidising atmosphere under controlled conditions up to 1,100°C with the purpose of obtaining information about structural changes that may be useful for pottery manufacture. X-ray fluorescence was used for the elemental characterization of the samples and X-ray diffractometry was used to determine the collapse and formation of the mineral phases present in the samples caused by thermal treatment. At temperatures above 1,000°C it is observed the formation of spinel in the case of White Greda and of hematite, corundum and cristobalite in the case of Red Greda. Room temperature transmission Mössbauer spectroscopy allowed the monitoring of the variation of the hyperfine parameters with the thermal treatment temperature; In the case of the evolution of the quadruple splitting of the paramagnetic Fe3 + sites with temperature, in both clays, the analyses reproduced results such as the “camel back” curve shape, found by other workers (Wagner and Wagner, Hyperfine Interact 154:35-82, 2004; Wagner and Kyek, Hyperfine Interact 154:5-33, 2004).

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.

Four new polymorphic forms of suplatast tosilate.

PubMed

Nagai, Keiko; Ushio, Takanori; Miura, Hidenori; Nakamura, Takashi; Moribe, Kunikazu; Yamamoto, Keiji

2014-01-02

We found four new polymorphic forms (γ-, ε-, ζ-, and η-forms) of suplatast tosilate (ST) by recrystallization and seeding with ST-analogous compounds; three polymorphic forms (α-, β-, and δ-forms) of ST have been previously reported. The physicochemical properties of these new forms were investigated using infrared (IR) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and powder X-ray diffractometry. The presence of hydrogen bonds in the new forms was assessed from the IR and solid-state NMR spectra. The crystal structures of the ε- and η-forms were determined from their powder X-ray diffraction data using the direct space approach and the Monte Carlo method, followed by Rietveld refinement. The structures determined for the ε- and η-forms supported the presence of hydrogen bonds between the ST molecules, as the IR and solid-state NMR spectra indicated. The thermodynamic characteristics of the seven polymorphic forms were evaluated by determining the solubility of each form. The α-form was the most insoluble in 2-propanol at 35°C, and was thus concluded to be the most stable form. The ε-form was the most soluble, and a polymorphic transition from the ε- to the α-form was observed during solubility testing. Copyright © 2013 Elsevier B.V. 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.

Properties and Applications of High Emissivity Composite Films Based on Far-Infrared Ceramic Powder

PubMed Central

Xiong, Yabo; Huang, Shaoyun; Wang, Wenqi; Liu, Xinghai; Li, Houbin

2017-01-01

Polymer matrix composite materials that can emit radiation in the far-infrared region of the spectrum are receiving increasing attention due to their ability to significantly influence biological processes. This study reports on the far-infrared emissivity property of composite films based on far-infrared ceramic powder. X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray powder diffractometry were used to evaluate the physical properties of the ceramic powder. The ceramic powder was found to be rich in aluminum oxide, titanium oxide, and silicon oxide, which demonstrate high far-infrared emissivity. In addition, the micromorphology, mechanical performance, dynamic mechanical properties, and far-infrared emissivity of the composite were analyzed to evaluate their suitability for strawberry storage. The mechanical properties of the far-infrared radiation ceramic (cFIR) composite films were not significantly influenced (p ≥ 0.05) by the addition of the ceramic powder. However, the dynamic mechanical analysis (DMA) properties of the cFIR composite films, including a reduction in damping and shock absorption performance, were significant influenced by the addition of the ceramic powder. Moreover, the cFIR composite films showed high far-infrared emissivity, which has the capability of prolonging the storage life of strawberries. This research demonstrates that cFIR composite films are promising for future applications. PMID:29186047

Properties and Applications of High Emissivity Composite Films Based on Far-Infrared Ceramic Powder.

PubMed

Xiong, Yabo; Huang, Shaoyun; Wang, Wenqi; Liu, Xinghai; Li, Houbin

2017-11-29

Polymer matrix composite materials that can emit radiation in the far-infrared region of the spectrum are receiving increasing attention due to their ability to significantly influence biological processes. This study reports on the far-infrared emissivity property of composite films based on far-infrared ceramic powder. X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray powder diffractometry were used to evaluate the physical properties of the ceramic powder. The ceramic powder was found to be rich in aluminum oxide, titanium oxide, and silicon oxide, which demonstrate high far-infrared emissivity. In addition, the micromorphology, mechanical performance, dynamic mechanical properties, and far-infrared emissivity of the composite were analyzed to evaluate their suitability for strawberry storage. The mechanical properties of the far-infrared radiation ceramic (cFIR) composite films were not significantly influenced ( p ≥ 0.05) by the addition of the ceramic powder. However, the dynamic mechanical analysis (DMA) properties of the cFIR composite films, including a reduction in damping and shock absorption performance, were significant influenced by the addition of the ceramic powder. Moreover, the cFIR composite films showed high far-infrared emissivity, which has the capability of prolonging the storage life of strawberries. This research demonstrates that cFIR composite films are promising for future applications.

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.

Recrystallization of starches by hydrothermal treatment: digestibility, structural, and physicochemical properties.

PubMed

Trinh, Khanh Son

2015-12-01

Gelatinized starches were recrystallized under hydrothermal treatment and their properties were characterized by X-ray diffractometry, solid-state (13)C cross-polarization and magic-angle spinning nuclear magnetic resonance, differential scanning calorimetry, gel-permeation chromatography, high-performance anion-exchange chromatography using pulsed amperomeric detection, high-performance size-exclusion chromatography with attached multiangle laser light scattering and refractive index detectors, and digestibility analysis. Amylopectin molecules of hylon (V, VII) and water yam starch contained long side-chains with high proportion of fb1 and fb2. Under hydrothermal treatment, the double helix proportion and relative crystallinity significantly increased and reached maxima of water yam (48.7 and 28.2 %, respectively). Except water yam starch, X-ray diffraction pattern of all starches exhibited the evidence of type 2 amylose-lipid complex. Besides, under DSC measurement, potato and hylon starches showed the endotherm of amylose-amylose interaction. The hydrothermal treatment caused the recrystallization resulting in the decrease of RDS, especially in case of hylon and water yam starch. HTT water yam contained highest SDS (48.3 %) and HTT hylon VII contained highest RS (44.5 %). The relationship between structure and digestibility was observed, in which, high amylose content and specific structures of amylopectin molecule were necessary for the production of RS and/or SDS of hydrothermally treated starches.

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.

Preparation of Zr(Mo,W)2O8 with a larger negative thermal expansion by controlling the thermal decomposition of Zr(Mo,W)2(OH,Cl)2∙2H2O.

PubMed

Petrushina, Mariya Yu; Dedova, Elena S; Filatov, Eugeny Yu; Plyusnin, Pavel E; Korenev, Sergei V; Kulkov, Sergei N; Derevyannikova, Elizaveta A; Sharafutdinov, Marat R; Gubanov, Alexander I

2018-03-28

Solid solutions of Zr(Mo,W) 2 O 7 (OH,Cl) 2 ∙2H 2 O with a preset ratio of components were prepared by a hydrothermal method. The chemical composition of the solutions was determined by energy dispersive X-ray spectroscopy (EDX). For all the samples of ZrMo x W 2-x O 7 (OH,Cl) 2 ∙2H 2 O (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0), TGA and in situ powder X-ray diffraction (PXRD) studies (300-1100 K) were conducted. For each case, the boundaries of the transformations were determined: Zr(Mo,W) 2 O 7 (OH,Cl) 2 ∙2H 2 O → orthorhombic-ZrMo x W 2-x O 8 (425-525 K), orthorhombic-ZrMo x W 2-x O 8  → cubic-ZrMo x W 2-x O 8 (700-850 K), cubic-ZrMo x W 2-x O 8  → trigonal-ZrMo x W 2-x O 8 (800-1050 K for x > 1) and cubic-ZrMo x W 2-x O 8  → oxides (1000-1075 K for x ≤ 1). The cell parameters of the disordered cubic-ZrMo x W 2-x O 8 (space group Pa-3) were measured within 300-900 K, and the thermal expansion coefficients were calculated: -3.5∙10 -6  - -4.5∙10 -6  K -1 . For the ordered ZrMo 1.8 W 0.2 O 8 (space group P2 1 3), a negative thermal expansion (NTE) coefficient -9.6∙10 -6  K -1 (300-400 K) was calculated. Orthorhombic-ZrW2O 8 is formed upon the decomposition of ZrW 2 O 7 (OH,Cl) 2 ∙2H 2 O within 500-800 K.

Synthesis of tritium breeder ceramics from metallic lithium

NASA Astrophysics Data System (ADS)

Knitter, R.; Kolb, M. H. H.; Odemer, C.

2012-01-01

For the fabrication of Li-6 enriched ceramic breeder materials for ITER, the availability of Li-6 enriched compounds is limited, and metallic Li-6 is the most widely available compound. As metallic lithium cannot be used directly in ceramic fabrication processes, we investigated different syntheses to obtain lithium orthosilicate or lithium metatitanate directly from molten lithium. In exothermic reactions of molten lithium with silicon, silica, or titania, several intermediate or precursor phases were observed under argon that could easily be transformed to the desired ceramic phases by a subsequent heat treatment under air. The reaction steps and the resulting phases were studied by differential scanning calorimetry and X-ray diffractometry. The synthesis from lithium and silicon seems to be especially suited for the production of larger quantities and has the advantage that silicon is available with a very high grade of purity.

Second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass.

PubMed

Cao, Q P; Li, J F; Zhang, P N; Horsewell, A; Jiang, J Z; Zhou, Y H

2007-06-20

The second amorphous-to-crystalline phase transformation in Cu(60)Ti(20)Zr(20) bulk metallic glass was investigated by differential scanning calorimetry and x-ray diffractometry. The difference of the Gibbs free energies between the amorphous phase and the crystalline products during the transformation is estimated to be about 2.46 kJ mol(-1) at 753 K, much smaller than the 61 kJ mol(-1) obtained assuming that it is a polymorphic transformation. It was revealed that the phase transformation occurs through a eutectic crystallization of Cu(51)Zr(14) and Cu(2)TiZr, having an effective activation energy of the order of 400 kJ mol(-1). The average Avrami exponent n is about 2.0, indicating that the crystallization is diffusion controlled.

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

Solid state polymerization and crystallography of polyimide precursors. Ph.D. Thesis - Va. Univ.

NASA Technical Reports Server (NTRS)

Wakelyn, N. T.

1974-01-01

Although the production of crystallinity in a polymeric system has historically led to commerically useful properties, the polyimides, prized for their high temperature characteristics, as customarily synthesized by melt or solution casting, are amorphous. It is shown that polymide containing residual crystallinity can be synthesized by isothermal annealing of crystals of the salt of the diisopropyl ester of pyromellitic acid and phenylene diamine. The reaction is topochemical in that the geometry of the polymer product is dependent upon that of the crystalline precursor. Infrared spectroscopy reveals the presence of imide absorption in the polymer, while powder diffractometry suggests residual crystallinity. Single crystal X-ray analysis of the monomer yields a structure of chains of alternating acid and base suggesting that the monomer is amenable to polymerization with a minimum of geometrical disruption.

On the dynamics of water molecules at the protein solute interfaces.

PubMed

Bernini, A; Spiga, O; Ciutti, A; Chiellini, S; Menciassi, N; Venditti, V; Niccolai, N

2004-10-01

Proteins, with the large variety of chemical groups they present at their molecular surface, are a class of molecules which can be very informative on most of the possible solute-solvent interactions. Hen egg white lysozyme has been used as a probe to investigate the complex solvent dynamics occurring at the protein surface, by analysing the results obtained from Nuclear Magnetic Resonance, X-ray diffractometry and Molecular Dynamics simulations. A consistent overall picture for the dynamics of water molecules close to the protein is obtained, suggesting that a rapid exchange occurs, in a picosecond timescale, among all the possible hydration surface sites both in solution and the solid state, excluding the possibility that solvent molecules can form liquid-crystal-like supramolecular adducts, which have been proposed as a molecular basis of 'memory of water'.

Improvement in elastic properties of CuAl{sub 0.4}Fe{sub 1.6}O{sub 4} spinel ferrite by rapid thermal cooling

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

Modi, K. B., E-mail: kunalbmodi2003@yahoo.com; Shah, S. J., E-mail: kunalbmodi2003@yahoo.com; Pathak, T. K., E-mail: kunalbmodi2003@yahoo.com

2014-04-24

The elastic properties of spinel ferrite composition, CuAl{sub 0.4}Fe{sub 1.6}O{sub 4}, quenched from final sintering temperature of 1373 K to liquid nitrogen temperature (∼ 80K) have been studied by means of X-ray powder diffractometry and pulse echo-overlap technique (9 MHz) at 300 K. The magnitude of elastic constants is found to enhance by 15% compared to slowly-cooled counterpart. The observed mechanical strengthening has been discussed in the light of compressive stress on the surface, with tensile stresses at interior regions and corresponding changes in structural parameters. The B{sub o}/G{sub o} ratio indicates the brittle nature of CuAl{sub 0.4}Fe{sub 1.6}O{sub 4}.

Analysis of NiAlTa precipitates in beta-NiAl + 2 at. pct Ta alloy

NASA Technical Reports Server (NTRS)

Pathare, V.; Michal, G. M.; Vedula, K.; Nathal, M. V.

1987-01-01

Results are reported from experiments performed to identify the precipitates, and their orientation in the matrix, in a beta-NiAl alloy containing 2 at. pct. Ta after undergoing creep test at 1300 K. Test specimens formed by extruding hot powders were compressed at 1300 K for about 50 hr at a strain rate averaging 6/1 million per sec. The specimens were then thinned and examined under an electron microscope and by X-ray diffractometry. An intermetallic NiAlTa compound with a hexagonal Cl4 structure appeared as second phase precipitates in the samples, exhibiting plate-like shapes and a habit plane close to (012). The prism planes of the hexagonal NiAlTa precipitates paralleled the closest packed planes in the cubic beta-NiAl matrix.

Alginate/cashew gum nanoparticles for essential oil encapsulation.

PubMed

de Oliveira, Erick F; Paula, Haroldo C B; de Paula, Regina C M

2014-01-01

Alginate/cashew gum nanoparticles were prepared via spray-drying, aiming at the development of a biopolymer blend for encapsulation of an essential oil. Nanoparticles were characterized regarding to their hydrodynamic volume, surface charge, Lippia sidoides essential oil content and release profile, in addition to being analyzed by infrared spectroscopy (FT-IR), thermal analysis (TGA/DSC) and X-ray diffractometry. Nanoparticles in solution were found to have averaged sizes in the range 223-399 nm, and zeta potential values ranging from -30 to -36 mV. Encapsulated oil levels varied from 1.9 to 4.4% with an encapsulation efficiency of up to 55%. The in vitro release profile showed that between 45 and 95% of oil was released within 30-50h. Kinetic studies revealed that release pattern follow a Korsmeyer-Peppas mechanism. Copyright © 2013 Elsevier B.V. All rights reserved.

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).

[Study on the traditional lime mortar from the memorial archway in the southern Anhui province].

PubMed

Wei, Guo-Feng; Sun, Sheng; Wang, Cheng-Xing; Zhang, Bing-Jian; Chen, Xi-Min

2013-07-01

The traditional lime mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of lime with tung oil or sticky rice. It was found that the excellent performance of the tung oil-lime mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of lime, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-lime mortar, which was produced due to carbonation process of lime controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.

Topochemical conversion of a dense metal–organic framework from a crystalline insulator to an amorphous semiconductor† †Electronic supplementary information (ESI) available: PXRD, impedance, TGA, IR, XPS, PDF, ESR, and CIF files. CCDC 1018776–1018778. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03295k Click here for additional data file.

PubMed Central

Hamoudi, H.; Suga, T.; Bennett, T. D.; Cairns, A. B.

2015-01-01

The topochemical conversion of a dense, insulating metal–organic framework (MOF) into a semiconducting amorphous MOF is described. Treatment of single crystals of copper(i) chloride trithiocyanurate, CuICl(ttcH3) (ttcH3 = trithiocyanuric acid), 1, in aqueous ammonia solution yields monoliths of amorphous CuI 1.8(ttc)0.6(ttcH3)0.4, 3. The treatment changes the transparent orange crystals of 1 into shiny black monoliths of 3 with retention of morphology, and moreover increases the electrical conductivity from insulating to semiconducting (conductivity of 3 ranges from 4.2 × 10–11 S cm–1 at 20 °C to 7.6 × 10–9 S cm–1 at 140 °C; activation energy = 0.59 eV; optical band gap = 0.6 eV). The structure and properties of the amorphous conductor are fully characterized by AC impedance spectroscopy, X-ray photoelectron spectroscopy, X-ray pair distribution function analysis, infrared spectroscopy, diffuse reflectance spectroscopy, electron spin resonance spectroscopy, elemental analysis, thermogravimetric analysis, and theoretical calculations. PMID:29560235

Positional isomeric tunable two Co(II) 6-connected 3-D frameworks with pentanuclear to binuclear units: structures, ion-exchange and magnetic properties.

PubMed

Han, Min-Le; Duan, Ya-Ping; Li, Dong-Sheng; Wang, Hai-Bin; Zhao, Jun; Wang, Yao-Yu

2014-11-07

Two new Co(II) based metal-organic frameworks, namely {[Co5(μ3-OH)2(m-pda)3(bix)4]·2ClO4}n (1) and {[Co2(p-pda)2(bix)2(H2O)]·H2O}n (2), were prepared by hydrothermal reactions of Co(II) salt with two isomeric dicarboxyl tectons 1,3-phenylenediacetic acid (m-pda) and 1,4-phenylenediacetic acid (p-pda), along with 1,3-bis(imidazol-L-ylmethyl)benzene (bix). Both complexes 1 and 2 have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). 1 shows a 6-connected 3-D pcu cationic framework with pentanuclear [Co5(μ3-OH)2(COO)6(bix)2](2+) units, while 2 exhibits a 6-connected 3-D msw net based on [Co2(μ2-H2O)(COO)2](2+) clusters. The results indicate that the different dispositions of the carboxylic groups of dicarboxylates have an important effect on the overall coordination frameworks. Perchlorate anions in 1 can be partly exchanged by thiocyanate and azide anions, however they are unavailable to nitrate anions. Magnetic susceptibility measurements indicate that both 1 and 2 show weak antiferromagnetic interactions between the adjacent Co(II) ions.

Characterisation, solubility and intrinsic dissolution behaviour of benzamide: dibenzyl sulfoxide cocrystal.

PubMed

Grossjohann, Christine; Eccles, Kevin S; Maguire, Anita R; Lawrence, Simon E; Tajber, Lidia; Corrigan, Owen I; Healy, Anne Marie

2012-01-17

This study examined the 1:1 cocrystal benzamide:dibenzyl sulfoxide, comprising the poorly water soluble dibenzyl sulfoxide (DBSO) and the more soluble benzamide (BA), to establish if this cocrystal shows advantages in terms of solubility and dissolution in comparison to its pure components and to a physical mixture. Solubility studies were performed by measuring DBSO solubility as a function of BA concentration, and a ternary phase diagram was constructed. Dissolution was examined through intrinsic dissolution studies. Solid-state characterisation was carried out by powder X-ray diffraction (PXRD), energy-dispersive X-ray diffraction (EDX), infra-red spectroscopy (ATR-FTIR) and thermal analysis. DBSO solubility was increased by means of complexation with BA. For the cocrystal, the solubility of both components was decreased in comparison to pure components. The cocrystal was identified as metastable and incongruently saturating. Dissolution studies revealed that dissolution of DBSO from the cocrystal was not enhanced in comparison to the pure compound or a physical mix, while BA release was retarded and followed square root of time kinetics. At the disk surface a layer of DBSO was found. The extent of complexation in solution can change the stability of the complex substantially. Incongruent solubility and dissolution behaviour of a cocrystal can result in no enhancement in the dissolution of the less soluble component and retardation of release of the more soluble component. Copyright © 2011 Elsevier B.V. All rights reserved.

Efficient Capture of Perrhenate and Pertechnetate by a Mesoporous Zr Metal–Organic Framework and Examination of Anion Binding Motifs

DOE PAGES

Drout, Riki J.; Otake, Kenichi; Howarth, Ashlee J.; ...

2018-01-10

At the Hanford Site in southeastern Washington state, the U.S. Department of Energy intends to treat 56 million gallons of legacy nuclear waste by encasing it in borosilicate glass via vitrification. This process ineffectively captures radioactive pertechnetate (TcO 4–) because of the ion’s volatility, thereby requiring a different remediation method for this long-lived (t 1/2 = 2.1 × 10 5 years), environmentally mobile species. Currently available sorbents lack the desired combination of high uptake capacity, fast kinetics, and selectivity. Here, we evaluate the ability of the chemically and thermally robust Zr 6-based metal–organic framework (MOF), NU-1000, to capture perrhenate (ReOmore » 4–), a pertechnetate simulant, and pertechnetate. Our material exhibits an excellent perrhenate uptake capacity of 210 mg/g, reaches saturation within 5 min, and maintains perrhenate uptake in the presence of competing anions. Additionally, experiments with pertechnetate confirm perrhenate is a suitable surrogate. Single-crystal X-ray diffraction indicates both chelating and nonchelating perrhenate binding motifs are present in both the small pore and the mesopore of NU-1000. Postadsorption diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) further elucidates the uptake mechanism and powder X-ray diffraction (PXRD) and Brunauer–Emmett–Teller (BET) surface area analysis confirm the retention of crystallinity and porosity of NU-1000 throughout adsorption.« less

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

Alammar, Tarek; Cybinska, Joanna; Campbell, Paul S.

In this study, sonication of Ln(CH 3COO) 3·H 2O, Eu(CH 3COO) 3·H 2O and NaOH dissolved in the ionic liquid-butyl-3-methylimidazolium bis(trifluoromethane)sulfonylamide lead to Ln(OH) 3:Eu (Ln: Gd, La, Y) nanoparticles. Subsequent calcination at 800 °C for 3 h allowed to obtain Ln 2O 3:Eu nanopowders. Gd 2O 3 and Y 2O 3 were obtained in the C-type lanthanide sequioxide structure, whereas La 2O 3 crystallized in the A-type. Structure, morphology, and luminescent properties of the nano-oxides were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), dispersive X-ray (EDX), and photoluminescence (PL). SEM studies revealed that the synthesized Gdmore » 2O 3:Eu, La 2O 3:Eu, and Y 2O 3:Eu formed nano-spindle, -sheets, and -rods in shape, respectively. The nanoscale materials show very efficient red emission due to the intraconfigurational f–f transitions of Eu 3+. The quantum yields for Ln 2O 3:Eu (5%) were determined to be 4.2% for Ln=Gd, 13.8% for Ln=Y and 5.2% for Ln=La. The asymmetric ratio I 02/I 01 of Eu 3+ varies from 5.3 for Gd 2O 3, to 5.6 for Y 2O 3 to 6.5 for La 2O 3, which increased the color chromaticity.« less

Effect of molecular weight, temperature, and additives on the moisture sorption properties of polyethylene glycol.

PubMed

Baird, Jared A; Olayo-Valles, Roberto; Rinaldi, Carlos; Taylor, Lynne S

2010-01-01

Polyethylene glycol (PEG) is a hygroscopic polymer that undergoes the phenomenon of deliquescence once a critical relative humidity (RH(0)) is reached. The purpose of this study was to test the hypothesis that the deliquescence behavior of PEG will be affected by the polymer molecular weight, temperature, and the presence of additives. The deliquescence relative humidity for single component (RH(0)) and binary mixtures (RH(0,mix)) were measured using an automated gravimetric moisture analyzer at 25 and 40 degrees C. Changes in PEG crystallinity after exposure to moisture were qualitatively assessed using powder X-ray diffraction (PXRD). Optical microscopy was used to visually observe the deliquescence phenomenon. For single component systems, decreasing PEG MW and elevating the temperature resulted in a decrease in the observed RH(0). Physical mixtures of acetaminophen and anhydrous citric acid with both PEG 3350 and PEG 100,000 exhibited deliquescence (RH(0,mix)) at a relative humidity below that of either individual component. Qualitative changes in crystallinity were observed from the X-ray diffractograms for each PEG MW grade at high relative humidities, indicating that phase transformation (deliquescence) of the samples had occurred. In conclusion, it was found that the deliquescence behavior of PEG was affected by the polymer MW, temperature, and the presence of additives. This phenomenon may have important implications for the stability of PEG containing formulations.

Thiazole derivative-modified upconversion nanoparticles for Hg2+ detection in living cells

NASA Astrophysics Data System (ADS)

Gu, Bin; Zhou, Yi; Zhang, Xiao; Liu, Xiaowang; Zhang, Yuhai; Marks, Robert; Zhang, Hua; Liu, Xiaogang; Zhang, Qichun

2015-12-01

Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems.Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems. Electronic supplementary information (ESI) available: NMR, MALDI-TOF MS spectra, etc. See DOI: 10.1039/c5nr05286f

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

A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products.

PubMed

Kelleher, J F; Gilvary, G C; Madi, A M; Jones, D S; Li, S; Tian, Y; Almajaan, A; Senta-Loys, Z; Andrews, G P; Healy, A M

2018-07-10

The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Modified mesoporous silica nanoparticles for enhancing oral bioavailability and antihypertensive activity of poorly water soluble valsartan.

PubMed

Biswas, Nikhil

2017-03-01

The aim was to improve the oral bioavailability and antihypertensive activity of poorly soluble drug valsartan (VAL) by modifying the design and delivery of mesoporous silica nanoparticles (MSNs). The synthesized MSNs were functionalized with aminopropyl groups (AP-MSN) through postsynthesis and coated with pH sensitive polymer Eudragit L100-55 (AP-MSN-L100-55) for pH dependant sustain release of anionic VAL. MSNs were characterized by Brauner-Emmett-Teller (BET) surface area analyzer, zeta sizer, Field Emission Scanning Electron Microscope (FESEM), Powder X-Ray Diffraction (PXRD) and Differential Scanning Calorimetry (DSC). Functionalized MSNs showed highest entrapment efficiency (59.77%) due to strong ionic interaction with VAL. In vitro dissolution of M-MSN [MSN-VAL and AP-MSN-VAL-L100-55 mixed equally] at physiological conditions demonstrated immediate release (MSN-VAL fraction) followed by sustained release (AP-MSN-VAL-L100-55 fraction) of 96% VAL in 960min. The dramatic improvement in dissolution was attributed to the amorphization of crystalline VAL by MSNs as evidenced by DSC and PXRD studies. No noticeable cytotoxicity was observed for MSN, AP-MSN and AP-MSN-L100-55 in MTT assay. Pharmacokinetic study of M-MSN confirmed 1.82 fold increases in bioavailability compared to commercial Diovan tablet in fasted male rabbits. Blood pressure monitoring in rats showed that the morning dosing of Diovan tablet efficiently controlled BP for just over 360min whereas the effect of M-MSN lasted for >840min. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of stability-enhanced ternary solid dispersions via combinations of HPMCP and Soluplus® processed by hot melt extrusion.

PubMed

Albadarin, Ahmad B; Potter, Catherine B; Davis, Mark T; Iqbal, Javed; Korde, Sachin; Pagire, Sudhir; Paradkar, Anant; Walker, Gavin

2017-10-30

The aim of this study was to evaluate a novel combination of hydroxypropyl methylcellulose phthalate (HPMCP-HP-50) and Soluplus ® polymers for enhanced physicochemical stability and solubility of the produced amorphous solid dispersions (ASDs). This was achieved using hot melt extrusion (HME) to convert the crystalline active pharmaceutical ingredient (API) into a more soluble amorphous form within the ternary systems. Itraconazole (ITZ), a Biopharmaceutics Classification System class II (BCS II) API, was selected as the model drug. The ASDs were characterized by Powder X-Ray diffraction (PXRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Solid State Nuclear Magnetic Resonance (ssNMR) and dissolution studies. The data showed that the ASDs were physically and chemically stable at 20°C and 50% RH over 12 months. PXRD results indicated that the ITZ in the ASDs was in the amorphous state and no recrystallization occurred. DSC scans confirmed that each formulation exhibited a single intermediate glass transition (T g ), around 96.4°C, indicating that ITZ was completely miscible in the polymeric blends of HPMCP and Soluplus ® at up to 30% (w/w) drug loading and that the two polymers were miscible with each other in the presence of ITZ. The FTIR analysis indicated the formation of strong hydrogen bonding between ITZ, HPMCP and Soluplus ® . The dissolution end-point of the ASDs was determined to be approximately 10 times greater than that of the crystalline ITZ. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel strategy for pharmaceutical cocrystal generation without knowledge of stoichiometric ratio: myricetin cocrystals and a ternary phase diagram.

PubMed

Hong, Chao; Xie, Yan; Yao, Yashu; Li, Guowen; Yuan, Xiurong; Shen, Hongyi

2015-01-01

To develop a streamlined strategy for pharmaceutical cocrystal preparation without knowledge of the stoichiometric ratio by preparing and characterizing the cocrystals of myricetin (MYR) with four cocrystal coformers (CCF). An approach based on the phase solubility diagram (PSD) was used for MYR cocrystals preparation and the solid-state properties were characterized by differential scanning calorimetry (DSC), fourier transform-infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The ternary phase diagram (TPD) was constructed by combining the PSD and nuclear magnetic resonance (NMR) data. After that, the TPD was verified by traditional methods. The dissolution of MYR in the four cocrystals and pure MYR within three different media were also evaluated. A simple research method for MYR cocrystal preparation was obtained as follows: first, the PSD of MYR and CCF was constructed and analyzed; second, by transforming the curve in the PSD to a TPD, a region of pure cocrystals formation was exhibited, and then MYR cocrystals were prepared and identified by DSC, FT-IR, PXRD, and SEM; third, with the composition of the prepared cocrystal from NMR, the TPD of the MYR-CCF-Solvent system was constructed. The powder dissolution data showed that the solubility and dissolution rate of MYR was significantly enhanced by the cocrystals. A novel strategy for pharmaceutical cocrystals preparation without knowledge of the stoichiometric ratio based on the TPD was established and MYR cocrystals were successfully prepared. The present study provides a systematic approach for pharmaceutical cocrystal generation, which benefits the development and application of cocrystal technology in drug delivery.

Peptide conjugated polymeric nanoparticles as a carrier for targeted delivery of docetaxel.

PubMed

Kulhari, Hitesh; Pooja, Deep; Shrivastava, Shweta; V G M, Naidu; Sistla, Ramakrishna

2014-05-01

The aim of this research work was to develop Bombesin peptide (BBN) conjugated, docetaxel loaded nanocarrier for the treatment of breast cancer. Docetaxel loaded nanoparticles (DNP) were prepared by solvent evaporation method using sodium cholate as surfactant. BBN was conjugated to DNP surface through covalent bonding. Both DNP and BBN conjugated DNP (BDNP) were characterized by various techniques such as dynamic light scattering, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis. The particle diameter and zeta potential of BDNP were 136±3.95 nm and -10.8±2.7 mV, respectively. The change in surface charge and FTIR studies confirmed the formation of amide linkage between BBN and DNP. AFM analysis showed that nanoparticles were spherical in shapes. In nanoparticles, docetaxel was present in its amorphous form as confirmed by DSC and PXRD analysis and was stable during the thermal studies. The formulations showed the sustained release of DTX over the period of 120 h. During cellular toxicity assay in gastrin releasing peptide receptor positive breast cancer cells (MDA-MB-231), BDNP were found to be 12 times more toxic than pure DTX and Taxotere. The IC50 value for DTX, Taxotere, DNP and BDNP was >375, >375, 142.23 and 35.53 ng/ml, respectively. The above studies showed that Bombesin conjugated nanocarrier system could be a promising carrier for active targeting of anticancer drugs in GRP receptor over expressing cancer cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Adsorption onto Mesoporous Silica Using Supercritical Fluid Technology Improves Dissolution Rate of Carbamazepine-a Poorly Soluble Compound.

PubMed

Gandhi, Aditya V; Thipsay, Priyanka; Kirthivasan, Bharat; Squillante, Emilio

2017-11-01

The purpose of this research was to design and characterize an immediate-release formulation of carbamazepine (CBZ), a poorly soluble anti-epileptic drug, using a porous silica carrier. Carbon dioxide in its supercritical state (2000 psi, 30-35°C) was used as an anti-solvent to precipitate CBZ onto two particle size variants of silica. Adsorption isotherms were used as a pre-formulation strategy to select optimum ratios of silica and CBZ. The obtained drug-silica formulations were characterized by dissolution studies, differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). This formulation strategy resulted in a 2.4-fold improvement in dissolution rate when compared to pure drug after 30 min of dissolution testing. PXRD and DSC confirmed the amorphous nature of CBZ in the formulations as well as the differences in polymorphic forms of commercial and supercritical fluid-processed CBZ. Additionally, solid-state NMR spectroscopy showed that the spin-lattice relaxation time for bulk drug (without silica) was ∼7.5 times greater than that for silica-confined CBZ, implying that when CBZ was adsorbed onto mesoporous silica, it is structurally disordered and had higher structural mobility, a characteristic of amorphous solids. The mesoporous silica matrix prevented CBZ crystal growth by imposing spatial constraint on CBZ nuclei and hence resulted in faster dissolution compared to bulk solid drug. Adsorption onto mesoporous silica using supercritical fluid technology may be used as a novel formulation strategy for amorphization of poorly soluble compounds, in turn improving their dissolution rate.

Investigation of Thermal and Viscoelastic Properties of Polymers Relevant to Hot Melt Extrusion, IV: Affinisol™ HPMC HME Polymers.

PubMed

Gupta, Simerdeep Singh; Solanki, Nayan; Serajuddin, Abu T M

2016-02-01

Most cellulosic polymers cannot be used as carriers for preparing solid dispersion of drugs by hot melt extrusion (HME) due to their high melt viscosity and thermal degradation at high processing temperatures. Three HME-grade hydroxypropyl methylcelluloses, namely Affinisol™ HPMC HME 15 cP, Affinisol™ HPMC HME 100 cP, and Affinisol™ HPMC HME 4 M, have recently been introduced by The Dow Chemical Co. to enable the preparation of solid dispersion at lower and more acceptable processing temperatures. In the present investigation, physicochemical properties of the new polymers relevant to HME were determined and compared with that of Kollidon(®) VA 64. Powder X-ray diffraction (PXRD), modulated differential scanning calorimetry (mDSC), thermogravimetric analysis (TGA), moisture sorption, rheology, and torque analysis by melt extrusion were applied. PXRD and mDSC showed that the Affinisol™ polymers were amorphous in nature. According to TGA, the onset of degradation for all polymers was >220°C. The Affinisol™ polymers exhibited less hygroscopicity than Kollidon(®) VA 64 and another HPMC polymer, Methocel™ K100LV. The complex viscosity profiles of the Affinisol™ polymers as a function of temperature were similar. The viscosity of the Affinisol™ polymers was highly sensitive to the shear rate applied, and unlike Kollidon(®) VA 64, the viscosity decreased drastically when the angular frequency was increased. Because of the very high shear rate encountered during melt extrusion, Affinisol™ polymers showed capability of being extruded at larger windows of processing temperatures as compared to that of Kollidon(®) VA 64.

In vitro characterization of a novel polymeric system for preparation of amorphous solid drug dispersions.

PubMed

Mahmoudi, Zahra N; Upadhye, Sampada B; Ferrizzi, David; Rajabi-Siahboomi, Ali R

2014-07-01

Preparation of amorphous solid dispersions using polymers is a commonly used formulation strategy for enhancing the solubility of poorly water-soluble drugs. However, often a single polymer may not bring about a significant enhancement in solubility or amorphous stability of a poorly water-soluble drug. This study describes application of a unique and novel binary polymeric blend in preparation of solid dispersions. The objective of this study was to investigate amorphous solid dispersions of glipizide, a BCS class II model drug, in a binary polymeric system of polyvinyl acetate phthalate (PVAP) and hypromellose (hydroxypropyl methylcellulose, HPMC). The solid dispersions were prepared using two different solvent methods: rotary evaporation (rotavap) and fluid bed drug layering on sugar spheres. The performance and physical stability of the dispersions were evaluated with non-sink dissolution testing, powder X-ray diffraction (PXRD), and modulated differential scanning calorimetry (mDSC). PXRD analysis demonstrated an amorphous state for glipizide, and mDSC showed no evidence of phase separation. Non-sink dissolution testing in pH 7.5 phosphate buffer indicated more than twofold increase in apparent solubility of the drug with PVAP-HPMC system. The glipizide solid dispersions demonstrated a high glass transition temperature (Tg) and acceptable chemical and physical stability during the stability period irrespective of the manufacturing process. In conclusion, the polymeric blend of PVAP-HPMC offers a unique formulation approach for developing amorphous solid dispersions with the flexibility towards the use of these polymers in different ratios and combined quantities depending on drug properties.

Thermal Processing of PVP- and HPMC-Based Amorphous Solid Dispersions.

PubMed

LaFountaine, Justin S; Prasad, Leena Kumari; Brough, Chris; Miller, Dave A; McGinity, James W; Williams, Robert O

2016-02-01

Thermal processing technologies continue to gain interest in pharmaceutical manufacturing. However, the types and grades of polymers that can be utilized in common thermal processing technologies, such as hot-melt extrusion (HME), are often limited by thermal or rheological factors. The objectives of the present study were to compare and contrast two thermal processing methods, HME and KinetiSol® Dispersing (KSD), and investigate the influence of polymer type, polymer molecular weight, and drug loading on the ability to produce amorphous solid dispersions (ASDs) containing the model compound griseofulvin (GRIS). Dispersions were analyzed by a variety of imaging, solid-state, thermal, and solution-state techniques. Dispersions were prepared by both HME and KSD using polyvinylpyrrolidone (PVP) K17 or hydroxypropyl methylcellulose (HPMC) E5. Dispersions were only prepared by KSD using higher molecular weight grades of HPMC and PVP, as these could not be extruded under the conditions selected. Powder X-ray diffraction (PXRD) analysis showed that dispersions prepared by HME were amorphous at 10% and 20% drug load; however, it showed significant crystallinity at 40% drug load. PXRD analysis of KSD samples showed all formulations and drug loads to be amorphous with the exception of trace crystallinity seen in PVP K17 and PVP K30 samples at 40% drug load. These results were further supported by other analytical techniques. KSD produced amorphous dispersions at higher drug loads than could be prepared by HME, as well as with higher molecular weight polymers that were not processable by HME, due to its higher rate of shear and torque output.

Anomalous magnetoelastic behaviour near morphotropic phase boundary in ferromagnetic Tb{sub 1-x}Nd{sub x}Co{sub 2} system

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

Murtaza, Adil; Yang, Sen, E-mail: yang.sen@mail.xjtu.edu.cn; Zhou, Chao

2016-08-01

In this work, we report a morphotropic phase boundary (MPB) involved ferromagnetic system Tb{sub 1-x}Nd{sub x}Co{sub 2} and reveal the corresponding structural and magnetoelastic properties of this system. With high resolution synchrotron X-ray diffractometry, the crystal structure of the TbCo{sub 2}-rich side is detected to be rhombohedral and that of NdCo{sub 2}-rich side is tetragonal below their respective Curie temperatures T{sub C}. The MPB composition Tb{sub 0.35}Nd{sub 0.65}Co{sub 2} corresponds to the coexistence of the rhombohedral phase (R-phase) and tetragonal phase (T-phase). Contrary to previously reported MPB involved ferromagnetic systems, the MPB composition of Tb{sub 0.35}Nd{sub 0.65}Co{sub 2} shows minimummore » magnetization which can be understood as compensation of sublattice moments between the R-phase and the T-phase. Furthermore, magnetostriction of Tb{sub 1-x}Nd{sub x}Co{sub 2} decreases with increasing Nd concentration until x = 0.8 and then increases in the negative direction with further increasing Nd concentration; the optimum point for magnetoelastic properties lies towards the rhombohedral phase. Our work not only shows an anomalous type of ferromagnetic MPB but also provides an effective way to design functional materials.« less

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.

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.

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

5-Arylidene derivatives of Meldrum's acid: Synthesis, structural characterization using single crystal and powder crystal X-ray diffraction, and electronic properties

NASA Astrophysics Data System (ADS)

Dey, Tanusri; Ghosh, Soumen; Ghosh, Somnath; Mukherjee, Alok Kumar

2015-07-01

Four 5-arylidene derivatives of Meldrum's acid, 5-(4-chlorobenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (2), 5-(3-hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (3), 5-(3,4-dimethoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4) and 5-(2,4-dimethoxy benzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (5) have been synthesized and their crystal structures have been determined using single crystal X-ray diffractometry for 2, 4 and 5 and X-ray powder diffraction for 3. The nature of intermolecular interactions in 2-5 has been analyzed through Hirshfeld surfaces and 2D fingerprint plots. The DFT optimized molecular geometries in 2-5 agree closely with those obtained from the crystallographic studies. The crystal packing in 2-5 exhibits an interplay of Osbnd H⋯O, Csbnd H⋯O, Csbnd H⋯Cl and Csbnd H⋯π (arene) hydrogen bonds and π⋯π interactions, which assemble molecules into three-dimensional architecture in 2, 3 and 5 and two-dimensional framework in 4. The Hirshfeld surface analyses of 2-5, Meldrum's acid (1) and a few related 5-arylidene derivatives of Meldrum's acid retrieved from the Cambridge Structural Database (CSD) indicate that about 85% of the Hirshfeld surface area (72% in 2 where H⋯Cl contribution is about 13%) in this class of compounds are due to H⋯H, O⋯H and C⋯H contacts. The HOMO-LUMO energy gap (>2.2 eV) in 2-5 indicates a significant degree of internal charge transfer within the molecule.

Correlation between the extent of catalytic activity and charge density of montmorillonites.

PubMed

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

2010-09-01

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.

Listvenite logging on D/V CHIKYU: Hole BT1B, Oman Drilling Project

NASA Astrophysics Data System (ADS)

Kelemen, P. B.; Beinlich, A.; Morishita, T.; Greenberger, R. N.; Johnson, K. T. M.; Lafay, R.; Michibayashi, K.; Harris, M.; Phase I Science Party, T. O. D. P.

2017-12-01

Listvenite, quartz-carbonate altered ultramafic rock containing minor fuchsite (Cr-muscovite) forms by complete carbonation of peridotite and is thus an attractive objective for carbon mitigation studies. However, reaction controls and evolution of listvenite are still enigmatic. Here we present the first results of Phase 1 of the ICDP (International Continental Drilling Program) Oman Drilling Project and subsequent core logging using the analytical facilities on board the research vessel D/V CHIKYU. Hole BT1B contains 300 m of continuous drill core intersecting alluvium, listvenite-altered serpentinite, serpentinite, ophicarbonate and the underlying metamorphic sole of the Semail ophiolite, Oman. The drill core has been systematically investigated by visual core description, thin section petrography, X-ray fluorescence core logging, X-ray diffractometry, visible-shortwave infrared imaging spectroscopy and X-ray Computer Tomography. Our observations show that listvenite is highly variable in texture and color on the mm to m scale. Listvenite was visually categorized into 5 principal color groups: the dominant dark red (47 %), light red (19 %), orange (14 %), pale (2 %) and green (16 %). The presence of hematite/goethite results in dark reddish, red and orange hues. Light grey or pale colored listvenite lacks hematite and/or goethite veins and may represent the `true' listvenite. Green listvenite is characterized by the presence of cm-sized quartz-fuchsite intergrowths. Five zones of serpentinite, which vary in thickness between several tens of cm and 4 m, are intercalated within the massive listvenite of Hole BT1B. Gradational listvenite-serpentinite transition zones contain the ophicarbonate assemblage (magnesite + serpentine) and sometimes additional talc, representing intermediate carbonation reaction progress. Preservation of the former mesh texture and bastite after orthopyroxene in the listvenite suggest that the listvenite precursor had already been serpentinized prior to infiltration of the CO2-bearing alteration fluid.

Enantiomeric resolution and X-ray optical activity of a tricobalt extended metal atom chain† †Electronic supplementary information (ESI) available: Bond distances and angles for 2 and 3, thermal ellipsoid plots, packing diagrams, PXRD data, magnetization curves, thermogravimetric analysis, and additional XNCD and XMCD plots and CD spectra. CCDC 1574514–1574516 and 1588703. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04131d

PubMed Central

Srinivasan, Anandi; Cortijo, Miguel; Bulicanu, Vladimir; Naim, Ahmad; Clérac, Rodolphe; Rogalev, Andrei; Wilhelm, Fabrice; Rosa, Patrick

2017-01-01

A simple procedure based on anion exchange was employed for the enantiomeric resolution of the extended metal atom chain (EMAC) [Co3(dpa)4(MeCN)2]2+. Use of the chiral salt (NBu4)2[As2(tartrate)2], (Λ-1 or Δ-1), resulted in the selective crystallization of the EMAC enantiomers as [Δ-Co3(dpa)4(MeCN)2](NBu4)2[Λ-As2(tartarte)2]2, (Δ-2) and [Λ-Co3(dpa)4(MeCN)2](NBu4)2[Δ-As2(tartrate)2]2 (Λ-2), respectively, in the P4212 space group, whereas a racemic mixture of 1 yielded [Co3(dpa)4(MeCN)2][As2(tartrate)2]·2MeCN (rac-3), which crystallized in the C2/c space group. The local electronic and magnetic structure of the EMAC enantiomers was studied, exploiting a variety of dichroisms in single crystals. A strong linear dichroism at the Co K-edge was observed in the orthoaxial configuration, whereas it vanished in the axial orientation, thus spectroscopically confirming the D4 crystal symmetry. Compounds Δ-2 and Λ-2 are shown to be enantiopure materials as evidenced by mirror-image natural circular dichroism spectra in the UV/vis in solution and in the X-ray range at the Co K-edge in single crystals. The surprising absence of detectable X-ray magnetic circular dichroism or X-ray magnetochiral dichroism signals at the Co K-edge, even at low temperature (3 K) and a high magnetic field (17 T), is ascribed to a strongly delocalized spin density on the tricobalt core. PMID:29675158

Zn(1-x)Cu(x)O (0.02 ≤ x ≤ 0.1) Nanomaterials Prepared by Ball Milling, Citrate Sol Gel, and Molten Salt Flux Methods.

PubMed

Balamurugan, S; Melba, K

2015-06-01

The Cu doped ZnO, (Zn(1-x)Cu(x))O (x = 0.02, 0.04, 0.06, 0.08, and 0.1) nanomaterials were prepared by ball milling technique (BMT), citrate sol gel (CSG), and molten salt flux (MSF) methods. The various as-prepared (Zn(1-x)Cu(x))O materials were analyzed by powder X-ray diffraction (pXRD), FT-IR, and SEM-EDX measurements in order to check the phase formation, purity, surface morphology and elements present in the annealed materials. Due to the preparation methods as well as doping of 'x' slight variations in cell parameters are seen. The average crystalline size of CSG method shows smaller size (25-35 nm) than BMT and MSF approaches. The materials obtained by MSF technique reveal the average crystalline size in the range of 32-72 nm whereas the BMT materials exhibit 36-50 nm for the composition, 0.02 ≤ x ≤ 0.1. The presence of functional groups and the chemical bonding in (Zn(1-x)Cu(x))O system is confirmed through FT-IR measurements. It is evident from the FT-IR data that bands seen at 400-500 cm(-1) are characteristics of M-O (M = metal ion) bonding in the studied materials. The micro images observed by SEM exhibiting polycrystalline character as compared with the crystallite size obtained from XRD. Among the three approaches employed in the present investigations, in terms of average particle size the CSG method may be concluded as an efficient method for the preparation of Zn(1-x)Cu(x)O nanomaterials.

Homochiral coordination polymers with helixes and metal clusters based on lactate derivatives

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

Xu, Zhong-Xuan, E-mail: xuzhongxuan4201@163.com; Ma, Yu-Lu; Lv, Guo-ling

2017-05-15

Utilizing the lactic acid derivatives (R)-4-(1-carboxyethoxy)benzoic acid (denoted: (R)-H{sub 2}CBA) and (S)-4-(1-carboxyethoxy)benzoic acid (denoted: (S)-H{sub 2}CBA)as chiral linkers to self-assemble with 4, 4′-bipyridine (denoted: BIP) and Cd(II) ions, a couple of three-dimensional homochiral coordination polymers, namely [Cd{sub 3}((R)-CBA){sub 3} (BIP){sub 2}(H{sub 2}O)]·xGuest (1-D) and [Cd{sub 3}((S)-CBA){sub 3}(BIP){sub 2}(H{sub 2}O)]·xGuest (1-L), have been synthesized under solvothermal reaction condition. Single crystal X-ray diffraction analysis reveals the two complexes contain single helical chains based on enantiopure ligands and cadmium clusters. Moreover, some physical characteristics such as PXRD, thermal stability, solid-state circular dichroism (CD) and luminescent were also investigated. - Graphical abstract: Utilizing enantiomericmore » lactic acid derivatives (R)-H{sub 2}CBA and (S)-H{sub 2}CBA to assemble with Cd{sup 2+} ions and ancillary BIP ligands, a couple of 3D homochiral coordination polymers with metal clusters and helical chains have been prepared by hydrothermal reaction. - Highlights: • Chiral lactic acid derivative. • Enantiomeric coordination polymer. • Helical chain. • Trinuclear cadmium cluster.« less

Driving the photoluminescent and structural properties of X2-Y2SiO5 by varying the dopant Dy3+ concentration towards cool WLED applications

NASA Astrophysics Data System (ADS)

Ramakrishna, G.; Nagabhushana, H.; Hareesh, K.; Sunitha, D. V.

2017-07-01

Dy3+ doped Y2SiO5 nanophosphors were synthesized by solution combustion technique using Calotropis gigantean milk latex and NaCl as fuel and flux respectively. Powder X-ray diffraction (PXRD) confirmed the formation of monoclinic X2-phase Y2SiO5 belonging to the phase group C2/c. Fourier transform infrared spectroscopy (FTIR) shows characteristic metal-oxygen (Y-O) vibration band at 721 cm-1. Transmission electron microscopic (TEM) and Scanning electron microscopic (SEM) morphological feature exhibits non-uniform almost spherical shaped nanosized particles. The photoluminescence (PL) emission peaks, recorded at 388 nm, showed radiative emissions at 483, 575 and 636 nm respectively. Judd-Ofelt (JO) analysis was carried out to estimate the radiative (AR) properties, radiative life time (τR), branching ratio (βR) and stimulated emission crossection (σλp). The CIE and CCT was estimated using McCamy empirical formula. In the beginning, the CIE co-ordinate values were lying in the light blue region. However, with increase in Dy3+ concentration the values shifted towards white region. CCT value was found to be ∼6984 K. Therefore, Y2SiO5:Dy3+ (9 mol%) can be used for cool day light and WLED applications.

β-Ketoiminato-based copper(ii) complexes as CVD precursors for copper and copper oxide layer formation.

PubMed

Pousaneh, Elaheh; Korb, Marcus; Dzhagan, Volodymyr; Weber, Marcus; Noll, Julian; Mehring, Michael; Zahn, Dietrich R T; Schulz, Stefan E; Lang, Heinrich

2018-06-19

The synthesis of ketoiminato copper(ii) complexes [Cu(OCRCHC(CH3)NCH2CH2X)(μ-OAc)]2 (X = NMe2: 4a, R = Me; 4b, R = Ph. X = OMe: 5, R = Me) and [Cu(OCRCHCMeNCH2CH2NEt2)(OAc)] (6, R = Me) from RC(O)CHC(CH3)N(H)CH2CH2X (X = NMe2: 1a, R = Me; 1b, R = Ph. X = NEt2: 1c, R = Me. X = OMe: 2, R = Me) and [Cu(OAc)2·H2O] (3) is reported. The molecular solid-state structures of 4-6 were determined by single crystal X-ray diffraction studies, showing that 4a,b and 5 are dimers which are set up by two [{Cu(μ-OAc)L}] (L = ketoiminato ligand) units featuring a square-planar Cu2O2 core with a distorted square-pyramidal geometry at Cu(ii). In contrast, 6 is monomeric with a tridentate-coordinated OCMeCHCMeNCH2CH2NEt2 ligand and a σ-bonded acetate group, thus inducing a square-planar environment around Cu(ii). The thermal behavior of all complexes was studied by TG (Thermogravimetry) and DSC (Differential Scanning Calorimetry) under an atmosphere of Ar and O2. Complex 4b shows the highest first onset temperature at 213 °C (under O2) and 239 °C (Ar). PXRD studies confirmed the formation of CuO under an atmosphere of O2 and Cu/Cu2O under Ar. TG-MS studies, exemplarily carried out with 4a, indicate the elimination of the ketoiminato ligands with detectable fragments such as m/z = 15, 28, 43, 44, 45, and 60 at a temperature above 250 °C. Vapor pressure measurements displayed that 5 shows the highest volatility of 3.6 mbar at 70 °C (for comparison, 4a, 1.4; 4b, 1.3; 6, 0.4 mbar) and hence 4a and 5 were used as MOCVD precursors for Cu/Cu2O deposition on Si/SiO2 at substrate temperatures of 450 °C and 510 °C. The deposition experiments were carried out under an atmosphere of nitrogen as well as oxygen. The as-obtained layers were characterized by SEM, EDX, XPS, and PXRD, showing that with oxygen as the reactive gas a mixture of metallic copper and copper(i) oxide without carbon impurities was formed, while under N2 Cu films with 53-68 mol% C contamination were produced. In a deposition experiment using precursor 5 at 510 °C under N2 a pure copper film was obtained.

Effect of particle in-flight behavior on the composition of thermal barrier coatings

NASA Astrophysics Data System (ADS)

Zhao, L.; Bai, Y.; Tang, J. J.; Liu, K.; Ding, C. H.; Yang, J. F.; Han, Z. H.

2013-12-01

In this work, 6 to 11 mol% YO1.5-stabilized zirconia (YSZ) coatings were deposited by supersonic and conventional atmospheric plasma spraying. During spraying, the surface temperature and velocity of in-flight particles were monitored by Spray Watch 2i on-line system. The phase composition of as-sprayed coatings was analyzed by X-ray diffractometry (XRD). Lattice parameters, tetragonality and the content of YO1.5 (mol%) of as-sprayed coatings were calculated according to the position of (0 0 4) and (4 0 0) diffraction peaks. It was found that the as-sprayed coatings were composed of metastable non-transformable tetragonal phase (t‧). However, the amount of YO1.5 (mol%) in the as-sprayed coatings decreased with the increase of melting index of in-flight particles due to the partial evaporation of YO1.5 during spraying.

Enhancing the bioavailability of magnolol in rabbits using melting solid dispersion with polyvinylpyrrolidone.

PubMed

Lin, Shiuan-Pey; Hou, Yu-Chi; Liao, Tzu-Yun; Tsai, Shang-Yuan

2014-03-01

Preparation of magnolol-loaded amorphous solid dispersion was investigated for improving the bioavailability. A solid dispersion of magnolol was prepared with polyvinylpyrrolidone K-30 (PVP) by melting method, and the physical properties were characterized by using differential scanning calorimetry, powder X-ray diffractometry, Fourier transformation-infrared spectroscopy and scanning electron microscope. In addition, dissolution test was also performed. Subsequently, the bioavailability of magnolol pure compound, its physical mixture and solid dispersion were compared in rabbits. The blood samples withdrawn via marginal ear vein at specific time points were assayed by HPLC method. Oral administration of the solid dispersion of magnolol with PVP significantly increased the systemic exposures of magnolol and magnolol sulfates/glucuronides by 80.1% and 142.8%, respectively, compared to those given with magnolol pure compound. Magnolol-loaded amorphous solid dispersion with PVP has demonstrated enhanced bioavailability of magnolol in rabbits.

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.

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

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.

Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding

PubMed Central

Rehder, Sönke; Klukkert, Marten; Löbmann, Korbinian A. M.; Strachan, Clare J.; Sakmann, Albrecht; Gordon, Keith; Rades, Thomas; Leopold, Claudia S.

2011-01-01

Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e., piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form of the piracetam and no polymorphic cocrystals were obtained. PMID:24309304

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.

Physicochemical analysis of Permian coprolites from Brazil

NASA Astrophysics Data System (ADS)

Rodrigues, M. I. C.; da Silva, J. H.; Santos, F. Eroni P.; Dentzien-Dias, P.; Cisneros, J. C.; de Menezes, A. S.; Freire, P. T. C.; Viana, B. C.

2018-01-01

In this paper we performed the study of two coprolites (fossilized feces) collected from the exposed levels of the Pedra de Fogo Formation, Parnaiba Sedimentary Basin, and Rio do Rasto Formation, Paraná Sedimentary Basin, both of the Palaeozoic era (Permian age). They were characterized using X-ray diffractometry, infrared, Raman and energy dispersive spectroscopy techniques in order to aid our understanding of the processes of fossilization and to discuss issues related to the feeding habits of the animals which generated those coprolites, probably cartilaginous fishes. The results obtained using a multitechnique approach showed that although these coprolites are from different geological formations, 3000 km away from each other, they show the same major crystalline phases and elemental composition. The main phases found were hydroxyapatite, silica, calcite and hematite, which lead to infer that those coprolites were formed under similar conditions and produced by a similar group of carnivore or omnivore fishes.

Rare earth doped M-type hexaferrites; ferromagnetic resonance and magnetization dynamics

NASA Astrophysics Data System (ADS)

Sharma, Vipul; Kumari, Shweta; Kuanr, Bijoy K.

2018-05-01

M-type hexagonal barium ferrites come in the category of magnetic material that plays a key role in electromagnetic wave propagation in various microwave devices. Due to their large magnetic anisotropy and large magnetization, their operating frequency exceeds above 50 GHz. Doping is a way to vary its magnetic properties to such an extent that its ferromagnetic resonance (FMR) response can be tuned over a broad frequency band. We have done a complete FMR study of rare earth elements neodymium (Nd) and samarium (Sm), with cobalt (Co) as base, doped hexaferrite nanoparticles (NPs). X-ray diffractometry, vibrating sample magnetometer (VSM), and ferromagnetic resonance (FMR) techniques were used to characterize the microstructure and magnetic properties of doped hexaferrite nanoparticles. Using proper theoretical electromagnetic models, various parameters are extracted from FMR data which play important role in designing and fabricating high-frequency microwave devices.

Effect of sandblasting on surface roughness of zirconia-based ceramics and shear bond strength of veneering porcelain.

PubMed

He, Min; Zhang, Zutai; Zheng, Dongxiang; Ding, Ning; Liu, Yan

2014-01-01

This study aims to investigate the effect of sandblasting on the surface roughness of zirconia and the shear bond strength of the veneering porcelain. Pre-sintered zirconia plates were prepared and divided into four groups. Group A were not treated at all; group B were first sandblasted under 0.2 MPa pressure and then densely sintered; group C and D were sintered first, and then sandblasted under 0.2 MPa and 0.4 MPa pressures respectively. Surface roughness was measured and 3D roughness was reconstructed for the specimens, which were also analyzed with X-ray diffractometry. Finally after veneering porcelain sintering, shear bond tests were conducted. Sandblasting zirconia before sintering significantly increased surface roughness and the shear bond strength between zirconia and veneering porcelain (p<0.05). Sandblasting zirconia before sintering is a useful method to increase surface roughness and could successfully improve the bonding strength of veneering porcelain.

Tuning optical properties of CdTe films with nanocolumnar morphology grown using OAD for improving light absorption in thin-film solar cells

NASA Astrophysics Data System (ADS)

Daza, L. G.; Canché-Caballero, V.; Chan y Díaz, E.; Castro-Rodríguez, R.; Iribarren, A.

2017-11-01

CdTe films with transversal morphology in form of tilted nanocolumns were obtained by sublimation method using a rotating vapour source combined with the oblique angle deposition technique. The tilt angles of the nanocolumnar structures increases as the substrate inclination also increase. CdTe films exhibited cubic zinc blend lattice under compressive strain. Morphological and x-ray diffractometry analysis indicated that the nanocolumns are grains stacked in the nanocolumn preferential growth direction, except for the films with non-inclined substrate. We found an interesting dependence of band gap energy and the refractive index as functions of the microstrain distribution due to the nanocolumn tilt in the films from 0° to about 25°. These facts evidence the possibility of carried out film strain engineering for optimizing optoelectronics devices as we propose for the case of thin-film solar cells.

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

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.

Experimental and calculated structural parameters of 5-trihalomethyl-4,5-dihydro-1 H-pyrazole derivatives, novel analgesic agents

NASA Astrophysics Data System (ADS)

Machado, Pablo; Campos, Patrick T.; Lima, Glauber R.; Rosa, Fernanda A.; Flores, Alex F. C.; Bonacorso, Helio G.; Zanatta, Nilo; Martins, Marcos A. P.

2009-01-01

The crystal structures of four novel analgesic agents, methyl 5-hydroxy-3- or 4-methyl-5-trichloro[trifluoro]methyl-4,5-dihydro-1 H-pyrazole-1-carboxylate, have been determined by X-ray diffractometry. The data demonstrated that the molecular packing was stabilized mainly by O sbnd H⋯O hydrogen bonds of the 5-hydroxy and 1-carboxymethyl groups. The 4,5-dihydro-1 H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0052-0.0805 Å. Additionally, computational investigation using semi-empirical AM1 and PM3 methods were performed to find a correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds.

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.

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.

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

Lattice damage and Al-metal precipitation in 2.5 MeV-electron-irradiated AlH3

NASA Astrophysics Data System (ADS)

Zogal, O. J.; Vajda, P.; Beuneu, F.; Pietraszko, A.

1998-04-01

AlH3 powder was bombarded with energetic electrons at 20 K and at room temperature and investigated by EPR, NMR, X-ray diffractometry, and microwave dielectric-constant measurements. The EPR spectra of the irradiated powder and of a selected single crystal cuboid of ˜ {10^{ - 1}} mm edge show a complex asymmetric line centered at g = 2.009, with a Curie-like temperature dependence, attributed to radiation-induced color centers and/or their agglomerates. At the same time, the grains, which have become shiny black after irradiation, exhibit an increase of both the real and the imaginary part of ɛ. 27Al-NMR spectra of the irradiated powder present a Knight-shifted line at 1600(50) ppm, close to the position of bulk metallic Al, and corresponding to a concentration of c(Al) ˜ {10^{ - 1}}. In addition, the main hydride line differs from that before irradiation, demonstrating an alteration of environmental symmetry. The irradiation induces also a change in shape and width of the 1H-NMR line, another indication of symmetry change in the lattice. Finally, a refined X-ray single-crystal structure analysis of the irradiated cuboid indicates a change of structure from trigonal R -3 c to R -3, with a loss of mirror symmetry for the two Al sites caused by the introduction of Al-defects in the vicinity of one of them.

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.

Modeling the formation of the quench product in municipal solid waste incineration (MSWI) bottom ash.

PubMed

Inkaew, Kanawut; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

2016-06-01

This study investigated changes in bottom ash morphology and mineralogy under lab-scale quenching conditions. The main purpose was to clarify the mechanisms behind the formation of the quench product/layer around bottom ash particles. In the experiments, the unquenched bottom ashes were heated to 300°C for 1h, and were quenched by warm water (65°C) with different simulated conditions. After having filtered and dried, the ashes were analyzed by a combination of methodologies namely, particle size distribution analysis, intact particle and thin-section observation, X-ray diffractometry, and scanning electron microscope with energy dispersive X-ray spectroscopy. The results indicated that after quenching, the morphology and mineralogy of the bottom ash changed significantly. The freshly quenched bottom ash was dominated by a quench product that was characterized by amorphous and microcrystalline calcium-silicate-hydrate (CSH) phases. This product also enclosed tiny minerals, glasses, ceramics, metals, and organic materials. The dominant mineral phases produced by quenching process and detected by XRD were calcite, Friedel's salt, hydrocalumite and portlandite. The formation of quench product was controlled by the fine fraction of the bottom ash (particle size <0.425mm). From the observations, a conceptual model of the ash-water reactions and formation of the quench product in the bottom ash was proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

CuLi2Sn and Cu2LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for Li-ion batteries.

PubMed

Fürtauer, Siegfried; Effenberger, Herta S; Flandorfer, Hans

2014-12-01

The stannides CuLi 2 Sn (CSD-427095) and Cu 2 LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu 2 Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi 2 Sn, the space group F-43m. was verified (structure type CuHg 2 Ti; a =6.295(2) Å; wR 2 ( F ²)=0.0355 for 78 unique reflections). The 4( c ) and 4( d ) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu 2 LiSn, the space group P 6 3 / mmc was confirmed (structure type InPt 2 Gd; a =4.3022(15) Å, c =7.618(3) Å; wR 2 ( F ²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2( a ), 2( b ) and 4( e ). Both phases seem to be interesting in terms of application of Cu-Sn alloys as anode materials for Li-ion batteries.

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

Graphene oxide as a nanocarrier for controlled release and targeted delivery of an anticancer active agent, chlorogenic acid.

PubMed

Barahuie, Farahnaz; Saifullah, Bullo; Dorniani, Dena; Fakurazi, Sharida; Karthivashan, Govindarajan; Hussein, Mohd Zobir; Elfghi, Fawzi M

2017-05-01

We have synthesized graphene oxide using improved Hummer's method in order to explore the potential use of the resulting graphene oxide as a nanocarrier for an active anticancer agent, chlorogenic acid (CA). The synthesized graphene oxide and chlorogenic acid-graphene oxide nanocomposite (CAGO) were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetry and differential thermogravimetry analysis, Raman spectroscopy, powder X-ray diffraction (PXRD), UV-vis spectroscopy and high resolution transmission electron microscopy (HRTEM) techniques. The successful conjugation of chlorogenic acid onto graphene oxide through hydrogen bonding and π-π interaction was confirmed by Raman spectroscopy, FTIR analysis and X-ray diffraction patterns. The loading of CA in the nanohybrid was estimated to be around 13.1% by UV-vis spectroscopy. The release profiles showed favourable, sustained and pH-dependent release of CA from CAGO nanocomposite and conformed well to the pseudo-second order kinetic model. Furthermore, the designed anticancer nanohybrid was thermally more stable than its counterpart. The in vitro cytotoxicity results revealed insignificant toxicity effect towards normal cell line, with a viability of >80% even at higher concentration of 50μg/mL. Contrarily, CAGO nanocomposite revealed enhanced toxic effect towards evaluated cancer cell lines (HepG2 human liver hepatocellular carcinoma cell line, A549 human lung adenocarcinoma epithelial cell line, and HeLa human cervical cancer cell line) compared to its free form. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and characterization of a 1D chain-like Cu{sub 6} substituted sandwich-type phosphotungstate with pendant dinuclear Cu–azido complexes

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

Li, Yan-Ying; Zhao, Jun-Wei, E-mail: zhaojunwei@henu.edu.cn; Wei, Qi

A novel Cu–azido complex modified hexa-Cu{sup II} substituted sandwich-type phosphotungstate [Cu(en){sub 2}]([Cu{sub 2}(en){sub 2}(μ-1,1-N{sub 3}){sub 2}(H{sub 2}O)]{sub 2}[Cu{sub 6}(en){sub 2}(H{sub 2}O){sub 2}(B-α-PW{sub 9}O{sub 34}){sub 2}])·6H{sub 2}O (1) (en=ethylene-diamine) has been prepared under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 displays a beautiful 1-D chain architecture constructed from sandwich-type [Cu{sub 2}(en){sub 2}(μ-1,1-N{sub 3}){sub 2}(H{sub 2}O)]{sub 2}[Cu{sub 6}(en){sub 2}(H{sub 2}O){sub 2}(B-α-PW{sub 9}O{sub 34}){sub 2}]{sup 2−} units and [Cu(en){sub 2}]{sup 2+} linkers. To our knowledge, 1 represents the first hexa-Cu{sup II} sandwiched phosphotungstate with supporting Cu–azido complexes. - Graphical abstract: Themore » first hexa-Cu{sup II} sandwiched phosphotungstate with supporting Cu–azido complexes has been prepared and characterized. Display Omitted - Highlights: • Hexa-copper-substituted phosphotungstate. • Cu–azido complexes modified hexa-Cu{sup II} substituted sandwich-type polyoxometalate. • 1-D chain architecture built by hexa-copper-substituted polyoxotungstate units.« less

Syntheses, structures and selective dye adsorption of five formic-based coordination polymers prepared by in-situ hydrolysis of N, N‧-dimethylformamide

NASA Astrophysics Data System (ADS)

Zhu, Zheng; Meng, Xiang-min; Zhang, Dong-mei; Zhang, Xia; Wang, Mei; Jin, Fan; Fan, Yu-hua

2017-04-01

Five functional coordination polymers (formic-based CPs) namely: {[Cu2(CHOO)3(bibp)2]·CHOO}n (1), {[Co2(CHOO)3(bibp)2]·NO3·H2O}n (2), {[Ni2(CHOO)3(bibp)2]·NO3·H2O}n (3) [Co(CHOO)2(bbibp)]n (4) and [Zn(CHOO)2(bbibp)]n (5) (bibp=4,4‧-bis(imidazolyl)biphenyl, bbibp=4,4‧-bis(benzoimidazo-1-yl)biphenyl) have been successfully hydrothermally synthesized using the in-situ hydrolysis of N, N‧-dimethylformamide (DMF) as the source of formate. All of these five polymers were characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Complexes 1-3 have the similar three-dimensional 3D kag topological framework built from the bibp ligand as the support member between the neighboring formic planes. Both complexes 4 and 5 have the similar one-dimensional 1D linear chain which is further assembled into 3D supermolecular structure by C-H…O hydrogen bonds. The dyes adsorption experiments have also been investigated systematically. The results show that complexes 2 and 3 exhibit high selective adsorption ability towards anionic dyes in their aqueous solution. Moreover, complex 2 displays good reversibility in the process of the dyes adsorption-release. Meanwhile, the unusual blocking phenomenon was firstly observed when complex 2 was in MO/OIV aqueous solutions with different concentration.

Sonochemical synthesis of highly luminescent Ln 2O 3:Eu 3+ (Y, La, Gd) nanocrystals

DOE PAGES

Alammar, Tarek; Cybinska, Joanna; Campbell, Paul S.; ...

2015-05-12

In this study, sonication of Ln(CH 3COO) 3·H 2O, Eu(CH 3COO) 3·H 2O and NaOH dissolved in the ionic liquid-butyl-3-methylimidazolium bis(trifluoromethane)sulfonylamide lead to Ln(OH) 3:Eu (Ln: Gd, La, Y) nanoparticles. Subsequent calcination at 800 °C for 3 h allowed to obtain Ln 2O 3:Eu nanopowders. Gd 2O 3 and Y 2O 3 were obtained in the C-type lanthanide sequioxide structure, whereas La 2O 3 crystallized in the A-type. Structure, morphology, and luminescent properties of the nano-oxides were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), dispersive X-ray (EDX), and photoluminescence (PL). SEM studies revealed that the synthesized Gdmore » 2O 3:Eu, La 2O 3:Eu, and Y 2O 3:Eu formed nano-spindle, -sheets, and -rods in shape, respectively. The nanoscale materials show very efficient red emission due to the intraconfigurational f–f transitions of Eu 3+. The quantum yields for Ln 2O 3:Eu (5%) were determined to be 4.2% for Ln=Gd, 13.8% for Ln=Y and 5.2% for Ln=La. The asymmetric ratio I 02/I 01 of Eu 3+ varies from 5.3 for Gd 2O 3, to 5.6 for Y 2O 3 to 6.5 for La 2O 3, which increased the color chromaticity.« less

Cd(II)-coordination polymers based on tetracarboxylic acid and diverse bis(imidazole) ligands: Synthesis, structural diversity and photoluminescence properties

NASA Astrophysics Data System (ADS)

Arıcı, Mürsel; Yeşilel, Okan Zafer; Taş, Murat

2017-01-01

Three new Cd(II)-coordination polymers, namely, {[Cd2(μ6-ao2btc)(μ-1,5-bipe)2]·2H2O}n (1), {[Cd2(μ6-ao2btc)(μ-1,4-bix)2]n·2DMF} (2) and {[Cd2(μ8-abtc)(μ-1,4-betix)]·DMF·H2O}n (3) (ao2btc=di-oxygenated form of 3,3‧,5,5‧-azobenzenetetracarboxylate, 1,5-bipe: 1,5-bis(imidazol-1yl)pentane, 1,4-bix=1,4-bis(imidazol-1ylmethyl)benzene, 1,4-betix=1,4-bis(2-ethylimidazol-1ylmethyl)benzene) were synthesized with 3,3‧,5,5‧-azobenzenetetracarboxylic acid and flexible, semi-flexible and semi-flexible substituted bis(imidazole) linkers. They were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and thermal analyses (TG/DTA). Complexes 1-3 exhibited structural diversities depending on flexible, semi-flexible and semi-flexible substituted bis(imidazole) ligands. Complex 1 was 2D structure with 3,6L18 topology. Complex 2 had a 3D pillar-layered framework with the rare sqc27 topology. When semi-flexible substituted bis(imidazole) linker was used, 3D framework of complex 3 was obtained with the paddlewheel Cd2(CO2)4-type binuclear SBU. Moreover, thermal and photoluminescence properties of the complexes were determined in detailed.

New hydrogen titanium phosphate sulfate electrodes for Li-ion and Na-ion batteries

NASA Astrophysics Data System (ADS)

Zhao, Ran; Mieritz, Daniel; Seo, Dong-Kyun; Chan, Candace K.

2017-03-01

NASICON-type materials with general formula AxM2(PO4)3 (A = Li or Na, M = Ti, V, and Fe) are promising candidates for Li- and Na-ion batteries due to their open three-dimensional framework structure. Here we report the electrochemical properties of hydrogen titanium phosphate sulfate, H0.4Ti2(PO4)2.4(SO4)0.6 (HTPS), a new mixed polyanion material with NASICON structure. Micron-sized HTPS aggregates with crystallite grain size of ca. 23 nm are synthesized using a sol-gel synthesis in an acidic medium. The properties of the as-synthesized HTPS, ball-milled HTPS, and samples prepared as carbon composites using an in-situ glucose decomposition reaction are investigated. A capacity of 148 mAh g-1 corresponding to insertion of 2 Li+ per formula unit is observed in the ball-milled HTPS over the potential window of 1.5-3.4 V vs. Li/Li+. Lithiation at ca. 2.8 and 2.5 V is determined to occur through filling of the M1 and M2 sites, respectively. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) are used characterize the HTPS before and after cycling. Evaluation of the HTPS in a Na-ion cell is also performed. A discharge capacity of 93 mAh g-1 with sodiation at ca. 2.9 and 2.2 V vs. Na/Na+ is observed.

Topological Transformation of a Metal–Organic Framework Triggered by Ligand Exchange

DOE PAGES

Miera, Greco Gonzalez; Gomez, Antonio Bermejo; Chupas, Peter J.; ...

2017-04-06

Metal-organic frameworks (MOFs) have shown to be unsuspectedly dynamic. Here we describe the topological interconversion of a new framework in the bio-MOF-100 family (dia-c) into the known isomer (lcs) by doubling the pore volume, which occurs during post-synthesis modifications. During this transformation, re-assembling of the MOF building blocks into a completely different framework occurs, involving breaking/forming of metal-ligand bonds. MOF crystallinity and local structure are retained, as determined by powder X-ray diffraction (PXRD) and pair distribution function (PDF) analyses, respectively. We have exploited the inherent dynamism of bio-MOF-100 by coupling chemical decorations of the framework using solvent-assisted ligand exchange (SALE)more » to the topological change. Following this method and starting from the pristine dense dia-c phase, open lcs-bio-MOF-100 was prepared and functionalized in-situ with an iridium complex (IrL). Alternatively, the dia-c MOF could be modified with wide-ranging amounts of IrL up to ca. 50 mol%, as determined by solution 1H Nuclear Magnetic Resonance (NMR) spectroscopy, by tuning the concentration of the solutions used and with no evidence for isomer interconversion. The single-site nature of the iridium complexes within the MOFs was assessed by X-ray absorption spectroscopy (XAS) and PDF analyses. As a result, ligand exchanges occurred quantitatively at room temperature, with no need of excess of the iridium metallolinker.« less

Rationale for the crystallization of titania polymorphs in solution

NASA Astrophysics Data System (ADS)

Kränzlin, N.; Staniuk, M.; Heiligtag, F. J.; Luo, L.; Emerich, H.; van Beek, W.; Niederberger, M.; Koziej, D.

2014-11-01

We use in situ X-ray absorption and diffraction studies to directly monitor the crystallization of different titania polymorphs in one and the same solution. We find that, despite the commonly accepted polymorphic-crossover from anatase to rutile triggered by the critical size of nanoparticles, in the solution their respective nucleation and growth are independent processes. Moreover, we find that 5.9 nm rutile nanoparticles are formed prior to the formation of 8.4 nm anatase nanoparticles. Our results suggest that the origins of this crystallization mechanism lie in the formation of an intermediate non-crystalline phase and in time-dependent changes in the chemical environment.We use in situ X-ray absorption and diffraction studies to directly monitor the crystallization of different titania polymorphs in one and the same solution. We find that, despite the commonly accepted polymorphic-crossover from anatase to rutile triggered by the critical size of nanoparticles, in the solution their respective nucleation and growth are independent processes. Moreover, we find that 5.9 nm rutile nanoparticles are formed prior to the formation of 8.4 nm anatase nanoparticles. Our results suggest that the origins of this crystallization mechanism lie in the formation of an intermediate non-crystalline phase and in time-dependent changes in the chemical environment. Electronic supplementary information (ESI) available: Detailed instructions on the experimental part including set-up, recorded XAS and PXRD raw data and their details. See DOI: 10.1039/c4nr04346d

Topological Transformation of a Metal–Organic Framework Triggered by Ligand Exchange

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

Miera, Greco Gonzalez; Gomez, Antonio Bermejo; Chupas, Peter J.

Metal-organic frameworks (MOFs) have shown to be unsuspectedly dynamic. Here we describe the topological interconversion of a new framework in the bio-MOF-100 family (dia-c) into the known isomer (lcs) by doubling the pore volume, which occurs during post-synthesis modifications. During this transformation, re-assembling of the MOF building blocks into a completely different framework occurs, involving breaking/forming of metal-ligand bonds. MOF crystallinity and local structure are retained, as determined by powder X-ray diffraction (PXRD) and pair distribution function (PDF) analyses, respectively. We have exploited the inherent dynamism of bio-MOF-100 by coupling chemical decorations of the framework using solvent-assisted ligand exchange (SALE)more » to the topological change. Following this method and starting from the pristine dense dia-c phase, open lcs-bio-MOF-100 was prepared and functionalized in-situ with an iridium complex (IrL). Alternatively, the dia-c MOF could be modified with wide-ranging amounts of IrL up to ca. 50 mol%, as determined by solution 1H Nuclear Magnetic Resonance (NMR) spectroscopy, by tuning the concentration of the solutions used and with no evidence for isomer interconversion. The single-site nature of the iridium complexes within the MOFs was assessed by X-ray absorption spectroscopy (XAS) and PDF analyses. As a result, ligand exchanges occurred quantitatively at room temperature, with no need of excess of the iridium metallolinker.« less

Phase Equilibria, Crystal Structure and Hydriding/Dehydriding Mechanism of Nd4Mg80Ni8 Compound

PubMed Central

Luo, Qun; Gu, Qin-Fen; Zhang, Jie-Yu; Chen, Shuang-Lin; Chou, Kuo-Chih; Li, Qian

2015-01-01

In order to find out the optimal composition of novel Nd-Mg-Ni alloys for hydrogen storage, the isothermal section of Nd-Mg-Ni system at 400 °C is established by examining the equilibrated alloys. A new ternary compound Nd4Mg80Ni8 is discovered in the Mg-rich corner. It has the crystal structure of space group I41/amd with lattice parameters of a = b = 11.2743(1) Å and c = 15.9170(2) Å, characterized by the synchrotron powder X-ray diffraction (SR-PXRD). High-resolution transmission electron microscopy (HR-TEM) is used to investigate the microstructure of Nd4Mg80Ni8 and its hydrogen-induced microstructure evolution. The hydrogenation leads to Nd4Mg80Ni8 decomposing into NdH2.61-MgH2-Mg2NiH0.3 nanocomposites, where the high density phase boundaries provide a great deal of hydrogen atoms diffusion channels and nucleation sites of hydrides, which greatly enhances the hydriding/dehydriding (H/D) properties. The Nd4Mg80Ni8 exhibits a good cycle ability. The kinetic mechanisms of H/D reactions are studied by Real Physical Picture (RPP) model. The rate controlling steps are diffusion for hydriding reaction in the temperature range of 100 ~ 350 °C and surface penetration for dehydriding reaction at 291 ~ 347 °C. In-situ SR-PXRD results reveal the phase transformations of Mg to MgH2 and Mg2Ni to Mg2NiH4 as functions of hydrogen pressure and hydriding time. PMID:26471964

Hydroxypropyl-β-cyclodextrin functionalized calcium carbonate microparticles as a potential carrier for enhancing oral delivery of water-insoluble drugs

PubMed Central

Zhang, Lihua; Zhu, Wufu; Lin, Qisi; Han, Jin; Jiang, Liqun; Zhang, Yanzhuo

2015-01-01

The objective of the present study was to demonstrate that a novel hydroxypropyl-β-cyclodextrin functionalized calcium carbonate (HP-β-CD/CC) based amorphous solid dispersion (ASD) can be used to increase the solubility and oral bioavailability of water-insoluble drugs. Irbesartan (IRB) was selected as a model compound and loaded into the nanoporous HP-β-CD/CC matrix using an immersion method. The IRB-loaded HP-β-CD/CC formulation was characterized by various analytical techniques, such as specific surface area analysis, scanning electron microscopy (SEM), dynamic light scattering (DLS), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). Analyses with PXRD and DSC confirmed that IRB was fully converted into the amorphous form in the nanopores of HP-β-CD/CC. From the solubility and dissolution tests, it was observed that the aqueous solubility and dissolution rate of IRB-loaded HP-β-CD/CC were increased significantly compared with those of pure IRB and IRB-loaded mesoporous silica. Likewise, the IRB-loaded HP-β-CD/CC formulation exhibited better absorption compared with that of the commercially available IRB capsules in beagle dogs. The mean peak plasma concentration (Cmax) and the area under the mean plasma concentration–time curve (AUC[0→48]) of IRB-loaded HP-β-CD/CC were 1.56- and 1.52-fold higher than that of the commercial product, respectively. Furthermore, the IRB-loaded HP-β-CD/CC formulation exhibited excellent stability against re-crystallization. These results clearly demonstrate that HP-β-CD/CC based porous ASD is a promising formulation approach to improve the aqueous solubility and the in vivo absorption performance of a water-insoluble compound like IRB. PMID:25995635

Diazole-based powdered cocrystal featuring a helical hydrogen-bonded network: structure determination from PXRD, solid-state NMR and computer modeling.

PubMed

Sardo, Mariana; Santos, Sérgio M; Babaryk, Artem A; López, Concepción; Alkorta, Ibon; Elguero, José; Claramunt, Rosa M; Mafra, Luís

2015-02-01

We present the structure of a new equimolar 1:1 cocrystal formed by 3,5-dimethyl-1H-pyrazole (dmpz) and 4,5-dimethyl-1H-imidazole (dmim), determined by means of powder X-ray diffraction data combined with solid-state NMR that provided insight into topological details of hydrogen bonding connectivities and weak interactions such as CH···π contacts. The use of various 1D/2D (13)C, (15)N and (1)H high-resolution solid-state NMR techniques provided structural insight on local length scales revealing internuclear proximities and relative orientations between the dmim and dmpz molecular building blocks of the studied cocrystal. Molecular modeling and DFT calculations were also employed to generate meaningful structures. DFT refinement was able to decrease the figure of merit R(F(2)) from ~11% (PXRD only) to 5.4%. An attempt was made to rationalize the role of NH···N and CH···π contacts in stabilizing the reported cocrystal. For this purpose four imidazole derivatives with distinct placement of methyl substituents were reacted with dmpz to understand the effect of methylation in blocking or enabling certain intermolecular contacts. Only one imidazole derivative (dmim) was able to incorporate into the dmpz trimeric motif thus resulting in a cocrystal, which contains both hydrophobic (methyl groups) and hydrophilic components that self-assemble to form an atypical 1D network of helicoidal hydrogen bonded pattern, featuring structural similarities with alpha-helix arrangements in proteins. The 1:1 dmpz···dmim compound I is the first example of a cocrystal formed by two different azoles. Copyright © 2014 Elsevier Inc. All rights reserved.

Designing MgFe2O4 decorated on green mediated reduced graphene oxide sheets showing photocatalytic performance and luminescence property

NASA Astrophysics Data System (ADS)

Shetty, Krushitha; Lokesh, S. V.; Rangappa, Dinesh; Nagaswarupa, H. P.; Nagabhushana, H.; Anantharaju, K. S.; Prashantha, S. C.; Vidya, Y. S.; Sharma, S. C.

2017-02-01

Here, a green route has been reported to convert Graphene Oxide (GO) to reduced graphene oxide (RGO) using clove extract. A modest and eco-accommodating sol-gel strategy has been employed to prepare MgFe2O4 nanoparticles, MgFe2O4-RGO nanocomposite samples. The samples were analyzed by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), UV-Visible Spectroscopy, Scanning Electron Microcopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Electrochemical Impedance Spectroscopy (EIS). PXRD result revealed that the prepared samples were cubic spinel in nature. SEM results uncovered flake like surface morphology of the prepared nanomaterial. Better PL emission signature was observed when excited at 329 nm. PL studies demonstrated that the present samples were potential for the fabrication of white component of white light emitting diodes (WLEDs). Further, MgFe2O4-RGO nanocomposite showed enhanced photocatalytic movement (PCM) and photostability under Sunlight in the decomposition of Malachite Green (MG) compared to MgFe2O4. This can be attributed to the interaction of MgFe2O4 surface with RGO sheets which results in PL quenching, demonstrates that the recombination of photo-induced electrons and holes in MgFe2O4-RGO nanocomposite is more effectively inhibited. A possible mechanism for the enhanced properties of MgFe2O4-RGO nanocomposite was discussed. Moreover, MgFe2O4-RGO photocatalyst also showed easy magnetic separation with high reusability. These results unveil that the synthesized sample can be used in display applications and also as a potential photocatalyst.

Combining 27Al Solid-State NMR and First-Principles Simulations To Explore Crystal Structure in Disordered Aluminum Oxynitride.

PubMed

Tu, Bingtian; Liu, Xin; Wang, Hao; Wang, Weimin; Zhai, Pengcheng; Fu, Zhengyi

2016-12-19

The nuclear magnetic resonance (NMR) technique gives insight into the local information in a crystal structure, while Rietveld refinement of powder X-ray diffraction (PXRD) sketches out the framework of a crystal lattice. In this work, first-principles calculations were combined with the solid-state NMR technique and Rietveld refinement to explore the crystal structure of a disordered aluminum oxynitride (γ-alon). The theoretical NMR parameters (chemical shift, δ iso , quadrupolar coupling constants, C Q , and asymmetry parameter, η) of Al 22.5 O 28.5 N 3.5 , predicted by the gauge-including projector augmented wave (GIPAW) algorithm, were used to facilitate the analytical investigation of the 27 Al magic-angle spinning (MAS) NMR spectra of the as-prepared sample, whose formula was confirmed to be Al 2.811 O 3.565 N 0.435 by quantitative analysis. The experimental δ iso , C Q , and η of 27 Al showed a small discrepancy compared with theoretical models. The ratio of aluminum located at the 8a to 16d sites was calculated to be 0.531 from the relative integration of peaks in the 27 Al NMR spectra. The occupancies of aluminum at the 8a and 16d positions were determined through NMR investigations to be 0.9755 and 0.9178, respectively, and were used in the Rietveld refinement to obtain the lattice parameter and anion parameter of Al 2.811 O 3.565 N 0.435 . The results from 27 Al NMR investigations and PXRD structural refinement complemented each other. This work provides a powerful and accessible strategy to precisely understand the crystal structure of novel oxynitride materials with multiple disorder.

Hydroxypropyl-β-cyclodextrin functionalized calcium carbonate microparticles as a potential carrier for enhancing oral delivery of water-insoluble drugs.

PubMed

Zhang, Lihua; Zhu, Wufu; Lin, Qisi; Han, Jin; Jiang, Liqun; Zhang, Yanzhuo

2015-01-01

The objective of the present study was to demonstrate that a novel hydroxypropyl-β-cyclodextrin functionalized calcium carbonate (HP-β-CD/CC) based amorphous solid dispersion (ASD) can be used to increase the solubility and oral bioavailability of water-insoluble drugs. Irbesartan (IRB) was selected as a model compound and loaded into the nanoporous HP-β-CD/CC matrix using an immersion method. The IRB-loaded HP-β-CD/CC formulation was characterized by various analytical techniques, such as specific surface area analysis, scanning electron microscopy (SEM), dynamic light scattering (DLS), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). Analyses with PXRD and DSC confirmed that IRB was fully converted into the amorphous form in the nanopores of HP-β-CD/CC. From the solubility and dissolution tests, it was observed that the aqueous solubility and dissolution rate of IRB-loaded HP-β-CD/CC were increased significantly compared with those of pure IRB and IRB-loaded mesoporous silica. Likewise, the IRB-loaded HP-β-CD/CC formulation exhibited better absorption compared with that of the commercially available IRB capsules in beagle dogs. The mean peak plasma concentration (C max) and the area under the mean plasma concentration-time curve (AUC[0→48]) of IRB-loaded HP-β-CD/CC were 1.56- and 1.52-fold higher than that of the commercial product, respectively. Furthermore, the IRB-loaded HP-β-CD/CC formulation exhibited excellent stability against re-crystallization. These results clearly demonstrate that HP-β-CD/CC based porous ASD is a promising formulation approach to improve the aqueous solubility and the in vivo absorption performance of a water-insoluble compound like IRB.

Enhancement of solubility and oral bioavailability of manidipine by formation of ternary solid dispersion with d-α-tocopherol polyethylene glycol 1000 succinate and copovidone.

PubMed

Chamsai, Benchawan; Limmatvapirat, Sontaya; Sungthongjeen, Srisagul; Sriamornsak, Pornsak

2017-12-01

Low bioavailability of oral manidipine (MDP) is due to its low water solubility. The objective of this study was to increase the solubility and bioavailability of MDP by fabricating ternary solid dispersion (tSD) with d-α-tocopherol polyethyleneglycol-1000-succinate and copovidone. In this study, solid ternary phase diagram was applied in order to check the homogeneity of tSD prepared by melting and solidifying with dry ice. The physicochemical properties of different formulations were determined by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and hot stage microscopy. Their solubility, dissolution, stability and bioavailability were also investigated. The results demonstrated that tSD obtained from ternary phase diagram divided into homogeneous and non-homogeneous regions. In the homogenous region, the transparent characteristics of tSD was observed and considered as a glass solution, which have a higher MDP solubility than that in non-homogenous region. The hot stage microscopy, DSC and PXRD confirmed that solid dispersion was formed in which MDP was molecularly dispersed in the carriers, especially in the homogenous region of phase diagram. FTIR analysis demonstrated strong hydrogen bonding between amine groups of MDP and carbonyl groups of copovidone, which supported a higher solubility and dissolution of tSD. The pharmacokinetic study in Wistar rats showed that the tSD had the greatest effect on oral bioavailability. Immediate hypotensive effect of tSD was also observed in vivo. The improvement of stability, dissolution and oral bioavailability of MDP could be achieved by using tSD technique.

Pressure-Induced Polymerization of LiN(CN) 2

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

Keefer, Derek W.; Gou, Huiyang; Purdy, Andrew P.

The high-pressure behavior of lithium dicyanamide (LiN(CN) 2) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time. On the basis of spectroscopic and diffraction data, we suggest a polymorphic phase transformation at ~8 GPa, wherein dicyanamide ions remain as discrete molecular species. Above ca. 18 GPa, dicyanamide units polymerize, forming a largely disorderedmore » network, and the extent of polymerization may be increased by annealing at elevated temperature. The polymerized product consists of tricyanomelaminate-like groups containing sp 2-hybidized carbon–nitrogen bonds and exhibits a visible absorption edge near 540 nm. The product is recoverable to ambient conditions but is not stable in air/moisture.« less

Enhancement of Oral Bioavailability of Curcumin by a Novel Solid Dispersion System.

PubMed

Hu, Liandong; Shi, Yanjing; Li, Jian Heng; Gao, Na; Ji, Jing; Niu, Feng; Chen, Queting; Yang, Xiaoning; Wang, Shaocheng

2015-12-01

The objective of this study was to improve the solubility and bioavailability of curcumin by a new curcumin dripping pills (Cur-DPs) formulation using melt mixing methods. The optimal formulation consisted of Polyethoxylated 40 hydrogenated castor oil (Cremophor RH40), Poloxamer 188, and Polyethylene glycol 4000 (PEG 4000). Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier-transform infrared spectroscopy (FT-IR) were used to verify the forming of Cur-DPs. All the physical characterization information proved the formation of Cur-DPs, and the results demonstrated the superiority of the dripping pills in dissolution rates. The pharmacokinetic study of Cur-DPs was performed in rats compared to the pure curcumin suspension. The oral bioavailability of poorly water-soluble curcumin was successfully improved by CUR-DPs. And the stability of prepared Cur-DP was also in a good state in 3 months. These results identified the Cur-DPs was an effective new approach for pharmaceutical application.

A novel stable 3D luminescent uranyl complex for highly efficient and sensitive recognition of Ru3+ and biomolecules

NASA Astrophysics Data System (ADS)

Tian, Hong-Hong; Chen, Liang-Ting; Zhang, Rong-Lan; Zhao, Jian-She; Liu, Chi-Yang; Weng, Ng Seik

2018-02-01

A novel highly stable 3D luminescent uranyl coordination polymer, namely {[UO2(L)]·DMA}n (1), was assembled with uranyl salt and a glycine-derivative ligand [6-(carboxymethyl-amino)-4-oxo-4,5-dihydro-[1,3,5]triazin-2-ylamino]-acetic acid (H2L) under solvothermal reaction. Besides, It was found that complex 1 possesses excellent luminescent properties, particularly the efficient selectivity and sensitivity in the recognition of Ru3+, biomacromolecule bovine serum albumin (BSA), biological small molecules dopamine (DA), ascorbic acid (AA) and uric acid (UA) in the water solution based on a "turn-off" mechanism. Accordingly, the luminescent explorations also demonstrated that complex 1 could be acted as an efficient luminescent probe with high quenching efficiency and low detection limit for selectively detecting Ru3+ and biomolecules (DA, AA, UA and BSA). It was noted that the framework structure of complex 1 still remains highly stable after quenching, which was verified by powder X-ray diffraction (PXRD).

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

Gao, Shan, E-mail: coralgao@hotmail.com; Engineering Ceramics Key Laboratory of Shandong Province, Shandong University, Jinan 250061; Sun, Kangning, E-mail: sunkangning@sdu.edu.cn

Highlights: ► We succeeded in synthesizing hydroxyapatite nano fibers by a chemical method. ► The reaction temperature is only 90 °C. ► The synthetic hydroxyapatite nano fiber is single crystal. - Abstract: We report a novel chemical precipitation route for the synthesis of hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, HA) fibers using surfactants as templates. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) reveal the characteristic peaks of HA. Transmission electron microscope (TEM) and high-resolution TEM revealed the nano structure, crystallinity and morphology of the HA fibers. The morphology of the HA fibers after calcinations were characterized bymore » scanning electron microscope (SEM). Br{sup −} ions were quickly replaced by the excess PO{sub 4}{sup 3−} ions in the solution after the addition of cetyltrime-thylammonium bromide (CTAB). Meanwhile, CTAB formed a rod-like micelles. Precursors reacted with PO{sub 4}{sup 3−} at the surface of CTAB micelles and finally formed the nanofiber structure.« less

Two intriguing hydroxy-copper(II) coordination polymers with bis(triazole) and bicarboxylate ligands: Syntheses, structures and photocatalytic degradation of organic dyes

NASA Astrophysics Data System (ADS)

Zhao, Shan; Zheng, Tian-Rui; Shi, Lu-Lu; Li, Ke; Li, Bao-Long; Li, Hai-Yan

2017-09-01

Two intriguing coordination polymers [Cu2(OH)(mbtx)(sip)(H2O)2]n (1) and {[Cu3(OH)2(mbtx)(nip)2]·H2O}n (2) were synthesized by the hydrothermal method and characterized by elementary analysis, IR, PXRD, diffuse reflectance spectra and single-crystal X-ray diffraction (mbtx = 1,3-bis(1,2,4-triazol-4-yl)benzene, sip = sulfoisophthalate, nip = 5-nitroisophthalate). 1 shows an unusual 3-connected 2D network based on the dimeric hydroxy-copper(II) cluster [Cu2(μ-OH)] with the point symbol of 63. 2 exhibits an unusual 3D network based on 1D hydroxyl-copper(II) chains [Cu3(OH)2]n. 1 and 2 are highly efficient and universal photocatalysts for the degradation of the organic dyes such as methyl orange (MO), methylene blue (MB) and rhodamine B (RhB) under UV irradiation. The photocatalytic mechanism was supposed.

Syntheses, structures and luminescence of three copper(I) cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene ligand

NASA Astrophysics Data System (ADS)

Shao, Min; Li, Ming-Xing; Lu, Li-Ruo; Zhang, Heng-Hua

2016-09-01

Three Cu(I)-cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene (tib) ligand, namely [Cu3(CN)3(tib)]n (1), [Cu4(CN)4(tib)]n (2), and [Cu2(CN)2(tib)]n (3), have been prepared and characterized by elemental analysis, IR, PXRD, thermogravimetry and single-crystal X-ray diffraction analysis. Complex 1 displays a 3D metal-organic framework with nanosized pores. Complex 2 is a 3D coordination polymer assembled by three μ2-cyanides and a μ3-cyanide with a very short Cu(I)···Cu(I) metal bond(2.5206 Å). Complex 3 is a 2D coordination polymer constructing from 1D Cu(I)-cyanide zigzag chain and bidentate tib spacer. Three Cu(I) complexes are thermally stable up to 250-350 °C. Complexes 1-3 show similar orange emission band at 602 nm originating from LMCT mechanism.

The bipyridine adducts of N-phenyldithiocarbamato complexes of Zn(II) and Cd(II); synthesis, spectral, thermal decomposition studies and use as precursors for ZnS and CdS nanoparticles

NASA Astrophysics Data System (ADS)

Onwudiwe, Damian C.; Strydom, Christien A.

2015-01-01

Bipyridine adducts of N-phenyldithiocarbamato complexes, [ML12L2] (M = Cd(II), Zn(II); L1 = N-phenyldithiocarbamate, L2 = 2,2‧ bipyridine), have been synthesized and characterised. The decomposition of these complexes to metal sulphides has been investigated by thermogravimetric analysis (TGA). The complexes were used as single-source precursors to synthesize MS (M = Zn, Cd) nanoparticles (NPs) passivated by hexadecyl amine (HDA). The growth of the nanoparticles was carried out at two different temperatures: 180 and 220 °C, and the optical and structural properties of the nanoparticles were studied using UV-Vis spectroscopy, photoluminescence spectroscopy (PL), transmission emission microscopy (TEM) and powdered X-ray diffraction (p-XRD). Nanoparticles, whose average diameters are 2.90 and 3.54 nm for ZnS, and 8.96 and 9.76 nm for CdS grown at 180 and 220 °C respectively, were obtained.

Terahertz spectra of l-phenylalanine and its monohydrate.

PubMed

Pan, Tingting; Li, Shaoping; Zou, Tao; Yu, Zheng; Zhang, Bo; Wang, Chenyang; Zhang, Jianbing; He, Mingxia; Zhao, Hongwei

2017-05-05

The low-frequency vibrational property of l-phenylalanine (l-Phe) and l-phenylalanine monohydrate (l-Phe·H 2 O) has been investigated by terahertz time-domain spectroscopy (THz-TDS) at room and low temperature ranging from 0.5 to 4.5THz. Distinctive THz absorption spectra of the two compounds were observed. Density functional theory (DFT) calculations based on the crystal structures have been performed to simulate the vibrational modes of l-Phe and l-Phe·H 2 O and the results agree well with the experimental observations. The study indicates that the characterized features of l-Phe mainly originate from the collective vibration of molecules. And the characterized features of l-Phe·H 2 O mainly come from hydrogen bond interactions between l-Phe and water molecules. l-Phe and l-Phe·H 2 O were also verified by differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) examinations. Copyright © 2017. Published by Elsevier B.V.

Fabrication of Fe3O4@CuO core-shell from MOF based materials and its antibacterial activity

NASA Astrophysics Data System (ADS)

Rajabi, S. K.; Sohrabnezhad, Sh.; Ghafourian, S.

2016-12-01

Magnetic Fe3O4@CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe3O4@HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe3O4 core and a CuO shell. The Fe3O4@CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe3O4-CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent.

Charge-transfer interaction of drug quinidine with quinol, picric acid and DDQ: Spectroscopic characterization and biological activity studies towards understanding the drug-receptor mechanism.

PubMed

Eldaroti, Hala H; Gadir, Suad A; Refat, Moamen S; Adam, Abdel Majid A

2014-04-01

Investigation of charge-transfer (CT) complexes of drugs has been recognized as an important phenomenon in understanding of the drug-receptor binding mechanism. Structural, thermal, morphological and biological behavior of CT complexes formed between drug quinidine (Qui) as a donor and quinol (QL), picric acid (PA) or dichlorodicyanobenzoquinone (DDQ) as acceptors were reported. The newly synthesized CT complexes have been spectroscopically characterized via elemental analysis; infrared (IR), Raman, 1 H NMR and electronic absorption spectroscopy; powder X-ray diffraction (PXRD); thermogravimetric (TG) analysis and scanning electron microscopy (SEM). It was found that the obtained complexes are nanoscale, semi-crystalline particles, thermally stable and spontaneous. The molecular composition of the obtained complexes was determined using spectrophotometric titration method and was found to be 1:1 ratios (donor:acceptor). Finally, the biological activities of the obtained CT complexes were tested for their antibacterial activities. The results obtained herein are satisfactory for estimation of drug Qui in the pharmaceutical form.

Terahertz spectroscopic investigation of gallic acid and its monohydrate

NASA Astrophysics Data System (ADS)

Zhang, Bo; Li, Shaoping; Wang, Chenyang; Zou, Tao; Pan, Tingting; Zhang, Jianbing; Xu, Zhou; Ren, Guanhua; Zhao, Hongwei

2018-02-01

The low-frequency spectra of gallic acid (GA) and its monohydrate were investigated by terahertz time-domain spectroscopy (THz-TDS) in the range of 0.5 to 4.5 THz. The dehydration process of GA monohydrate was monitored on-line. The kinetic mechanism of the dehydration process was analyzed depending on the THz spectral change at different temperatures. The results indicate that the diffusion of water molecule dominates the speed of the entire dehydration process. Solid-state density functional theory (DFT) calculations of the vibrational modes of both GA and its monohydrate were performed based on their crystalline structures for better interpreting the experimental THz spectra. The results demonstrate that the characterized features of GA mainly originate from the collective vibrations of molecules. And the interactions between GA and water molecules are responsible for THz fingerprint of GA monohydrate. Multi-techniques including differential scanning calorimetry and thermogravimetry (DSC-TG) and powder X-ray diffraction (PXRD) were also carried out to further investigate GA and its monohydrate.

Evaluation of High-Performance Curcumin Nanocrystals for Pulmonary Drug Delivery Both In Vitro and In Vivo

NASA Astrophysics Data System (ADS)

Hu, Liandong; Kong, Dongqian; Hu, Qiaofeng; Gao, Na; Pang, Saixi

2015-10-01

This paper focused on formulating high-performance curcumin spray-dried powders for inhalation (curcumin-DPIs) to achieve a high lung concentration. Curcumin-DPIs were produced using wet milling combined with the spray drying method. The effects of different milling times on particle size and aerodynamic performance were investigated. The curcumin-DPIs were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and in vitro dissolution. Furthermore, the in vivo pharmacokinetic behavior and tissue distribution after pulmonary administration were also evaluated. Results showed that the drug dissolution was significantly enhanced by processing into curcumin-DPIs. The aerodynamic results indicated that the DPIs displayed a good aerosol performance. The plasma curcumin concentration was obviously enhanced by inhalation, and most of the curcumin-DPIs were deposited in the lung. This study demonstrated that inhalation was an effective way to carry drug to the lung, and curcumin-DPIs were hopeful for lung cancer treatment in the future.

Adsorption of Pb(II) from aqueous solution using a magnetic chitosan/graphene oxide composite and its toxicity studies.

PubMed

Samuel, Melvin S; Shah, Sk Sheriff; Bhattacharya, Jayanta; Subramaniam, Kalidass; Pradeep Singh, N D

2018-05-02

This study involves the adsorption of lead using magnetic chitosan/graphene oxide (MCGO) composite material in batch mode. The MCGO composite material was synthesized via modified Hummers method. The MCGO composite material was characterized by powder x-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Tunnelling electron microscopy (TEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) and UV-vis diffusive reflectance spectra. The adsorption mechanism of MCGO composite material was well described by Langmuir isotherm and pseudo second order kinetic model, with a high regression coefficient (<0.99). The MCGO composite material was applied for the removal of lead metal from aqueous solution. We have also evaluated toxicity of synthesized MCGO composite material by examining on A549 cells. The results have shown that MCGO material showed viable cell percentage of 53.7% at 50 μg and 44.8% at 100 μg. Copyright © 2018 Elsevier B.V. All rights reserved.

Recrystallization of fluconazole using the supercritical antisolvent (SAS) process.

PubMed

Park, Hee Jun; Kim, Min-Soo; Lee, Sibeum; Kim, Jeong-Soo; Woo, Jong-Soo; Park, Jeong-Sook; Hwang, Sung-Joo

2007-01-10

The supercritical antisolvent (SAS) process was used to modify solid state characteristics of fluconazole. Fluconazole was recrystallized at various temperatures (60-80 degrees C) and pressures (8-16MPa) using dichloromethane (DCM) as a solvent. Acetone and ethanol were also employed as solvents. The fluconazole polymorphs prepared by the SAS process were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Furthermore, the equilibrium solubility of the samples in aqueous solution was determined. Fluconazole anhydrate form I was obtained at low temperature (40 degrees C) and anhydrate form II was obtained at high temperature (80 degrees C). The variation of pressure during the SAS process may influence the preferred orientation. Anhydrate forms I and II were also obtained using various solvents. Therefore, it was shown that solid state characteristics of fluconazole, including the polymorphic form and preferred orientation, can be controlled by changing operating conditions of the SAS process such as temperature, pressure, and solvent.

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.

Development of molecular precursors for deposition of indium sulphide thin film electrodes for photoelectrochemical applications.

PubMed

Ehsan, Muhammad Ali; Peiris, T A Nirmal; Wijayantha, K G Upul; Olmstead, Marilyn M; Arifin, Zainudin; Mazhar, Muhammad; Lo, K M; McKee, Vickie

2013-08-14

Symmetrical and unsymmetrical dithiocarbamato pyridine solvated and non-solvated complexes of indium(III) with the general formula [In(S2CNRR')3]·n(py) [where py = pyridine; R,R' = Cy, n = 2 (1); R,R' = (i)Pr, n = 1.5 (2); NRR' = Pip, n = 0.5 (3) and R = Bz, R' = Me, n = 0 (4)] have been synthesized. The compositions, structures and properties of these complexes have been studied by means of microanalysis, IR and (1)H-NMR spectroscopy, X-ray single crystal and thermogravimetric (TG/DTG) analyses. The applicability of these complexes as single source precursors (SSPs) for the deposition of β-In2S3 thin films on fluorine-doped SnO2 (FTO) coated conducting glass substrates by aerosol-assisted chemical vapour deposition (AACVD) at temperatures of 300, 350 and 400 °C is studied. All films have been characterized by powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDX) for the detection of phase and stoichiometry of the deposit. Scanning electron microscopy (SEM) studies reveal that precursors (1)-(4), irrespective of different metal ligand design, generate comparable morphologies of β-In2S3 thin films at different temperatures. Direct band gap energies of 2.2 eV have been estimated from the UV-vis spectroscopy for the β-In2S3 films fabricated from precursors (1) and (4). The photoelectrochemical (PEC) properties of β-In2S3 were confirmed by recording the current-voltage plots under light and dark conditions. The plots showed anodic photocurrent densities of 1.25 and 0.65 mA cm(-2) at 0.23 V vs. Ag/AgCl for the β-In2S3 films made at 400 and 350 °C from the precursors (1) and (4), respectively. The photoelectrochemical performance indicates that the newly synthesised precursors are highly useful in fabricating β-In2S3 electrodes for solar energy harvesting and optoelectronic application.

Development of Novel Garnet-Type Solid Electrolytes for Potential Application in Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Narayanan, Sumaletha

The development of promising solid electrolytes having a garnet-like structure has been successfully achieved through solid state (ceramic) method. Various approaches to improve the Li ion conductivity were employed. The first approach involved creating oxide ion vacancies into the crystal structure of parent garnet-like oxide, Li5La3Nb2O 12 to create a novel family of compounds with nominal composition, Li 5La3Nb2-xYxO12-δ (0 ≤ x ≤ 1). The second approach was Li stuffing into the garnet-like oxides to develop a series of Li stuffed novel Li5+2xLa3Nb 2-xYxO12 (0.05 ≤ x ≤ 0.75) and Li6.5 La2.5Ba0.5ZrTaO12. Powder X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) coupled with a wavelength-dispersive spectrometer (WDS), 7Li nuclear magnetic resonance (Li-NMR), and AC impedance spectroscopy were employed to characterize the structure, morphology, elemental composition, Li ion sites, and Li ion conductivity. Studies have shown that Li5+2xLa 3Nb2-xYxO12 have turned out to be promising solid electrolytes with high Li ion conductivity (10-4 Scm -1 at ambient temperatures). In addition, all families of garnets are found to be chemically stable with Li cathode materials (Li2MMn 3O8, where M = Fe, Co) up to 400 °C in air. The developed electrolyte materials have the potential to be used in all-solid-state Li ion batteries.

Influence of beta-cyclodextrin complexation on glipizide release from hydroxypropyl methylcellulose matrix tablets.

PubMed

Shivakumar, H N; Desai, B G; Pandya, Saumyak; Karki, S S

2007-01-01

Glipizide was complexed with beta-cyclodextrin in an attempt to enhance the drug solubility. The phase solubility diagram was classified as A(L) type, which was characterized by an apparent 1:1 stability constant that had a value of 413.82 M(-1). Fourier transform infrared spectrophotometry, differential scanning calorimetry, powder x-ray diffractometry and proton nuclear magnetic resonance spectral analysis indicated considerable interaction between the drug and beta-cyclodextrin. A 2(3) factorial design was employed to prepare hydroxypropyl methylcellulose (HPMC) matrix tablets containing the drug or its complex. The effect of the total polymer loads (X1), levels of HPMC K100LV (X9), and complexation (X3) on release at first hour (Y1), 24 h (Y2), time taken for 50% release (Y3), and diffusion exponent (Y4) was systematically analyzed using the F test. Mathematical models containing only the significant terms (P < 0.05) were generated for each parameter by multiple linear regression analysis and analysis of variance. Complexation was found to exert a significant effect on Y1, Y2, and Y3, whereas total polymer loads significantly influenced all the responses. The models generated were validated by developing two new formulations with a combination of factors within the experimental domain. The experimental values of the response parameters were in close agreement with the predicted values, thereby proving-the validity of the generated mathematical models.

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.

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.

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 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.

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

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

Fourspring, P.M.; Pangborn, R.N.

1997-12-31

X-ray double crystal diffractometry (XRDCD) was 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 XRDCD 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.more » 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 {micro}m), subsurface (10--300 {micro}m), 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. 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.« less

Structural and electrical characterization of NbO2 vertical devices grown on TiN coated SiO2/Si substrate

NASA Astrophysics Data System (ADS)

Joshi, Toyanath; Borisov, Pavel; Lederman, David

Due to its relatively high MIT temperature (1081 K) and current-controlled negative differential resistance, NbO2 is a robust candidate for memory devices and electrical switching applications. In this work, we present in-depth analysis of NbO2 thin film vertical devices grown on TiN coated SiO2/Si substrates using pulsed laser deposition (PLD). Two of the films grown in 1 mTorr and 10 mTorr O2/Ar (~7% O2) mixed growth pressures were studied. The formation of NbO2 phase was confirmed by Grazing Incidence X-ray Diffractometry (GIXRD), X-ray Photoelectron Spectroscopy (XPS) and current vs. voltage measurements. A probe station tip (tip size ~2 μm) or conductive AFM tip was used as a top and TiN bottom layer was used as a bottom contact. Device conductivity showed film thickness and contact size dependence. Current pulse measurements, performed in response to applied triangular voltage pulses, showed a non-linear threshold switching behavior for voltage pulse durations of ~100 ns and above. Self-sustained current oscillations were analyzed in terms of defect density presented in the film. Supported by FAME (sponsored by MARCO and DARPA, Contract 2013-MA-2382), WV Higher Education Policy Commission Grant (HEPC.dsr.12.29), and WVU SRF. We also thank S. Kramer from Micron for providing the TiN-coated Si substrates.

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.

Mono-Schiff-base or di-Schiff-base? Synthesis, spectroscopic, X-ray structural and DFT study of a series of Schiff-bases derived from benzil dihydrazone

NASA Astrophysics Data System (ADS)

Tan, Xue-Jie; Hao, Xiu-Qi; Zhao, Qing-Zhe; Cheng, Shuang-Shuang; Xie, Wen-Long; Xing, Dian-Xiang; Liu, Yun; Song, Lai-Zhou

2015-11-01

A series of mono- and di-Schiff-bases based on Benzil Dihydrazone (BDH) were designed and synthesized to be set as the model compounds to explain which one should be the advanced product and which parameters will determine the end-product. As the first step of a series of investigations, this article presents the syntheses and characterization of five new Schiff-bases plus one preliminary reported Schiff-base, all derived from BDH. The compounds were characterized by single crystal (or conventional powder) X-ray diffractometry, elemental analysis, m.p., 1H NMR, 13C NMR, IR and UV-Vis. Structural features of the five new Schiff-bases are similar. For instance, all molecules are nonsymmetrical/symmetrical double helix with the torsion angle of two "half-parts" about 72-97°. The Ph-Cdbnd N-Ndbnd C-Ph moiety all exists in planar and anti form, indicating significant conjugation. The crystal structures appear to be stabilized by π-stacking between the aromatic rings, as well as by intermolecular hydrogen bonds and C-H … π stacking interactions. DFT calculations have been performed to explain the trend of the experimentally measured reaction yields. In the case of the studied systems by us, the type of Schiff-bases exhibits a clear dependence on the molar ratio of reactants if the products have similar stabilities. Otherwise the importance of reaction conditions will be weakened and the most stable product will be favored.

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.

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.

Modification of hectorite by organofunctionalization for use in removing U(VI) from aqueous media: thermodynamic approach.

PubMed

Guerra, Denis L; Airoldi, Claudio; Viana, Rúbia R

2010-02-01

A Hectorite sample (H) has been chemically modified with N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulting materials (H(3TPT) and H(NPTM)) have been characterized through elemental analysis, X-ray diffractometry, carbon nuclear magnetic resonance in the solid state, textural analysis, and thermogravimetric analysis. The adsorption experiments were performed under batch process with pH, ionic strength, contact time, and uranyl concentration as variables. The attached basic centers adsorbed uranyl cation to give maxima adsorption capacity of 5.55+/-0.21, 14.86+/-0.05, and 18.99+/-0.05 x 10(-3) mmol g(-1) for H, H(3TPT), and H(NPTM), respectively. From calorimetric determinations the quantitative thermal effects for UO(2)(2+)/center interactions gave exothermic enthalpy (Delta(int)H=-6.90 to -7.88 kJ mol(-1)), negative Gibbs free energy (Delta(int)G=-22.34 to -24.56 kJ mol(-1)), and positive entropy (Delta(int)S=51.80-56.00 JK(-1)mol(-1)). These thermodynamic data confirmed the energetically favorable condition of such interaction solid/liquid for all systems. Copyright 2009. Published by Elsevier Ltd.

Synthesis, characterization and corrosion inhibition properties of benzamide-2-chloro-4-nitrobenzoic acid and anthranilic acid-2-chloro-4-nitrobenzoic acid for mild steel corrosion in acidic medium

NASA Astrophysics Data System (ADS)

Pandey, Archana; Verma, Chandrabhan; Singh, B.; Ebenso, Eno E.

2018-03-01

The present study deals with the synthesis of two new compounds namely, benzamide - 2-chloro-4-nitrobenzoic acid (BENCNBA) and anthranilic acid-2-chloro-4-nitrobenzoic acid (AACNBA) using solid phase reactions. The phase diagram studies revealed that formation of the investigated compounds occurs in 1:1 molar ratio. The synthesized compounds were characterized using several spectral techniques such as FT-IR, 1H and 13C NMR, UV-Vis, powder X-ray diffraction (PXRD). Single crystal XRD (SCXRD) study showed that both BENCNBA and AACNBA compounds crystallize in triclinic crystal system with P-1 space group. Further, the presence of intermolecular hydrogen bonding between the constituent components was also supported by single crystal X-ray diffraction (SCXRD) method. Heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions have also been computed using the enthalpy of fusion values derived from differential scanning calorimeter (DSC) study. The inhibition effect of BENCNBA and AACNBA on the mild steel corrosion in hydrochloric acid solution was tested using electrochemical methods. Electrochemical impedance spectroscopy (EIS) study revealed that both BENCNBA and AACNBA behaved as interface corrosion inhibitors and showed maximum inhibition efficiencies of 95.71% and 96.42%, respectively at 400 ppm (1.23 × 10-3 M) concentration. Potentiodynamic polarization (PDP) measurements suggested that BENCNBA and AACNBA acted as mixed type corrosion inhibitors. EIS and PDP results showed that BENCNBA and AACNBA act as efficient corrosion inhibitors for mild steel and their inhibition efficiencies enhances on increasing their concentrations.

Synthesis of highly stable silver nanoparticles through a novel green method using Mirabillis jalapa for antibacterial, nonlinear optical applications

NASA Astrophysics Data System (ADS)

Pugazhendhi, S.; Palanisamy, P. K.; Jayavel, R.

2018-05-01

Green synthesis techniques are developing as more simplistic and eco-friendly approach for the synthesis of metal nanoparticles compared to chemical reduction methods. Herein we report Synthesis of highly stable silver nanoparticles using Mirabillis jalapa seed extract as a reducing and capping agent. The as-prepared silver nanoparticles were characterized by UV-vis spectroscopy (UV-vis) to confirm the formation of silver nanoparticles by its characteristic surface plasmon resonance peak observed at 420 nm. The Powder X-ray diffraction (P-XRD) revealed the structure and crystalline nature of synthesized silver nanoparticles, The Fourier transform infra-red spectroscopic (FT-IR) revealed the presence of the biomolecules in the extract that acted as reducing as well stabilizing agent. The high resolution transmission electron microscopic (HRTEM) images divulged that the synthesized silver nanoparticles were spherical in shape and poly dispersed. The energy dispersive X-ray diffraction (EDX) profile revealed the elements present in the as-synthesized colloidal silver nanoparticles and its percentages. The Zeta potential measured for silver nanoparticles evidenced that the prepared silver nanoparticles owned high stability in room temperature itself. The as-synthesized silver nanoparticles (AgNPs) in colloidal form were showed good antimicrobial effects and it's were found to exhibit third order optical nonlinearity as studied by Z-scan technique using 532 nm Nd:YAG (SHG) CW laser beam (COHERENT-Compass 215 M-50 diode pumped) output as source. The negative nonlinearity observed was well utilized for the study of optical limiting behavior of the silver nanoparticles.

Structural, spectral and magnetic studies of two Co(II)-N-heterocyclic diphosphonates based on multinuclear units

NASA Astrophysics Data System (ADS)

Zhao, Chen; Ma, Kui-Rong; Zhang, Yu; Kan, Yu-He; Li, Rong-Qing; Hu, Hua-You

2016-01-01

Two examples of Co(II)-N-heterocyclic coordination polymers based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C(OH)(PO3H2)2), namely 0.5(H3NCH2CH2NH3)·[Co6(Cl2)(H3L)2(H2L)(HL)(2,2‧-bipy)6] 1 and 2(NH4)·[Co3(HL)2(H2O)2(phen)2]·2(H2O) 2, have been solvothermally obtained by introducing the second ligands 2,2‧-bipyridine/1,10-phenanthroline (2,2‧-bipy/phen) and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, TG-DSC. The single-crystal X-ray diffractions show that compound 1 possesses a 0-D structure with hexa-nuclear cluster [Co6(O-P-O)8] built through single/double O-P-O bridges and compound 2 displays a 1-D ladder-like chain structure with magnetic topology building blocks [Co4(O-P-O)4]n. Then H-bonding and π-π stacking interactions further expand the two low-dimensional structures into three-dimensional supramolecular frameworks. Fluorescent measurements reveal that both the maximum emission peaks of 1-2 are centered at 423 nm, mainly deriving from intraligand π*-π transition state of N-heterocyclic ligand 2,2‧-bipy/phen, respectively. Magnetism data indicate that 1 exhibits antiferromagnetic behavior within hexa-nuclear Co(II) clusters, while 2 shows weak ferromagnetic interactions in 1-D topology Co(II)-chain, showing promising potential as magnetic materials.