A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

PubMed Central

Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

2016-01-01

The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 − 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 −CoFe2O4 bulk composites with similar content of the ferrite phase. PMID:27555563

A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

NASA Astrophysics Data System (ADS)

Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

2016-08-01

The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 - 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 -CoFe2O4 bulk composites with similar content of the ferrite phase.

TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

2016-12-01

Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

X-ray diffraction and SEM study of kidney stones in Israel: quantitative analysis, crystallite size determination, and statistical characterization.

PubMed

Uvarov, Vladimir; Popov, Inna; Shapur, Nandakishore; Abdin, Tamer; Gofrit, Ofer N; Pode, Dov; Duvdevani, Mordechai

2011-12-01

Urinary calculi have been recognized as one of the most painful medical disorders. Tenable knowledge of the phase composition of the stones is very important to elucidate an underlying etiology of the stone disease. We report here the results of quantitative X-ray diffraction phase analysis performed on 278 kidney stones from the 275 patients treated at the Department of Urology of Hadassah Hebrew University Hospital (Jerusalem, Israel). Quantification of biominerals in multicomponent samples was performed using the normalized reference intensity ratio method. According to the observed phase compositions, all the tested stones were classified into five chemical groups: oxalates (43.2%), phosphates (7.7%), urates (10.3%), cystines (2.9%), and stones composed of a mixture of different minerals (35.9%). A detailed analysis of each allocated chemical group is presented along with the crystallite size calculations for all the observed crystalline phases. The obtained results have been compared with the published data originated from different geographical regions. Morphology and spatial distribution of the phases identified in the kidney stones were studied with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). This type of detailed study of phase composition and structural characteristics of the kidney stones was performed in Israel for the first time.

Comparing phase-sensitive and phase-insensitive echolocation target images using a monaural audible sonar.

PubMed

Kuc, Roman

2018-04-01

This paper describes phase-sensitive and phase-insensitive processing of monaural echolocation waveforms to generate target maps. Composite waveforms containing both the emission and echoes are processed to estimate the target impulse response using an audible sonar. Phase-sensitive processing yields the composite signal envelope, while phase-insensitive processing that starts with the composite waveform power spectrum yields the envelope of the autocorrelation function. Analysis and experimental verification show that multiple echoes form an autocorrelation function that produces near-range phantom-reflector artifacts. These artifacts interfere with true target echoes when the first true echo occurs at a time that is less than the total duration of the target echoes. Initial comparison of phase-sensitive and phase-insensitive maps indicates that both display important target features, indicating that phase is not vital. A closer comparison illustrates the improved resolution of phase-sensitive processing, the near-range phantom-reflectors produced by phase-insensitive processing, and echo interference and multiple reflection artifacts that were independent of the processing.

Final Report - Enhanced LAW Glass Property - Composition Models - Phase 1 VSL-13R2940-1, Rev. 0, dated 9/27/2013

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

Kruger, Albert A.; Muller, I.; Gilbo, K.

2013-11-13

The objectives of this work are aimed at the development of enhanced LAW propertycomposition models that expand the composition region covered by the models. The models of interest include PCT, VHT, viscosity and electrical conductivity. This is planned as a multi-year effort that will be performed in phases with the objectives listed below for the current phase.  Incorporate property- composition data from the new glasses into the database.  Assess the database and identify composition spaces in the database that need augmentation.  Develop statistically-designed composition matrices to cover the composition regions identified in the above analysis.  Preparemore » crucible melts of glass compositions from the statistically-designed composition matrix and measure the properties of interest.  Incorporate the above property-composition data into the database.  Assess existing models against the complete dataset and, as necessary, start development of new models.« less

Phase-Pure and Multiphase Ceramic Waste Forms: Microstructure Evolution and Cesium Immobilization

NASA Astrophysics Data System (ADS)

Tumurugoti, Priyatham

Efforts of this thesis are directed towards developing ceramic waste forms as a potential replacement for the conventional glass waste forms for the safe immobilization and disposal of nuclear wastes from the legacy weapons programs as well as commercial power production. The body of this work consists of two equal parts with first focused on multiphase waste form containing hollandite as major phase and the later, on single-phase hollandites for Cs incorporation. Part I: Multiphase waste forms:. Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by X-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirm hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of select elements observed by wavelength dispersive spectroscopy (WDS) maps indicate that Cs forms a secondary phase during SPS processing, which is considered undesirable. On the other hand Cs partitioned into hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition, by selected area electron diffraction (SAED), reveals ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice. Following the microstructural analysis, the crystallization behavior of the multiphase composition during melt-processing was studied. The phase assemblage and evolution of hollandite, zirconolite, pyrochlore, and perovskite type structures during melt processing were studied using thermal analysis, in-situ XRD, and scanning electron microscopy (SEM). Samples prepared by melting followed by annealing and quenching were analyzed to determine and measure the progression of the phase assemblage. Samples were melted at 1500°C and heat-treated at crystallization temperatures of 1285°C and 1325°C corresponding to exothermic events identified from differential scanning calorimetry (DSC) measurements. Results indicate that the selected multiphase composition partially melts at 1500°C with hollandite coexisting as crystalline phase. Perovskite and zirconolite phases crystallized from the residual melt at temperatures below 1350°C. Depending on their respective thermal histories, different quenched samples were found to have different phase assemblages including phases such as perovskite, zirconolite and TiO2. Part II: Single phase waste forms. Hollandites with compositions Ba1.15-xCs2xCr 2.3Ti5.7O16 have been identified as promising lattices to host Cs. Series of compositions with 0 ≤ x ≤ 1.15 were prepared by sol-gel synthesis, characterized, and analyzed for Cs retention properties. Phase-pure hollandites adopting monoclinic symmetry (I2/m) were observed to form in the compositional range 0 ≤ x ≤ 0.4. Structural models for the compositions: x = 0, 0.15, and 0.25, were developed from Rietveld analysis of powder XRD and neutron diffraction data. Refined anisotropic displacement parameters (beta ij) for Ba and Cs ions in the hollandite tunnels indicate local disorder of Ba/Cs along the tunnel direction. In addition, weak super lattice reflections have also been observed in XRD patterns. Our data suggests the presence of supercell structures with ordered tunnel cations for the phase-pure hollandites studied. Finally, the performance of phase-pure hollandites have been evaluated qualitatively by chemical durability testing and ion-irradiation experiments. Elemental analysis of the leachants after 7-day leach tests show that Cs and Cr were extracted from the lattice together. No direct correlation between structural parameters or Cs content was observed. The simulated light-ion (He2+) and heavy-ion (Kr3+) irradiation experiments reveal that all the hollandite compositions studied undergo amorphization during alpha-decay events, and the extent of it increases with the Cs content. In summary, the present work validates melt-processing as an effective method to prepare multiphase waste forms with the desired phase assemblage. Ba1.15-xCs2xCr2.3Ti5.7O16 hollandite has been identified as an effective ceramic host for Cs immobilization and appropriate structural models for hollandites with different Cs levels have been developed. The structural information may be used to study or simulate the lattice-environment interaction.

Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

PubMed

Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

2014-01-01

In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained.

Effect of Titanium Addition on the Thermal Properties of Diamond/Cu-Ti Composites Fabricated by Pressureless Liquid-Phase Sintering Technique

PubMed Central

Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

2014-01-01

In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m·K for 50 vol% diamond/Cu-0.6  at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained. PMID:24715816

Intestinal Microbiota of White Shrimp Penaeus vannamei Under Intensive Cultivation Conditions in Ecuador.

PubMed

Gainza, Oreste; Ramírez, Carolina; Ramos, Alfredo Salinas; Romero, Jaime

2018-04-01

The goal of the study was to characterize the intestinal tract bacterial microbiota composition of Penaeus vannamei in intensive commercial ponds in Ecuador, comparing two shrimp-farming phases: nursery and harvest. Bacterial microbiota was examined by sequencing amplicons V2-V3 of the 16S rRNA using Ion Torrent technology. Archaea sequences were detected in both phases. Sequence analyses revealed quantitative and qualitative differences between the nursery phase and the harvest phase in shrimp intestinal microbiota composition. The main differences were observed at the phylum level during the nursery phase, and the prevailing phyla were CKC4 (37.3%), Proteobacteria (29.8%), Actinobacteria (11.6%), and Firmicutes (10.1%). In the harvest phase, the prevailing phyla were Proteobacteria (28.4%), Chloroflexi (19.9%), and Actinobacteria (15.1%). At the genus level, microbiota from the nursery phase showed greater relative abundances of CKC4 uncultured bacterium (37%) and Escherichia-Shigella (18%). On the contrary, in the microbiota of harvested shrimp, the prevailing genera were uncultured Caldilinea (19%) and Alphaproteobacteria with no other assigned rate (10%). The analysis of similarity ANOSIM test (beta diversity) indicated significant differences between the shrimp microbiota for these two farming phases. Similarly, alfa-diversity analysis (Chao1) indicated that the microbiota at harvest was far more diverse than the microbiota during the nursery phase, which showed a homogeneous composition. These results suggest that shrimp microbiota diversify their composition during intensive farming. The present work offers the most detailed description of the microbiota of P. vannamei under commercial production conditions to date.

FIBER AND INTEGRATED OPTICS, LASER APPLICATIONS, AND OTHER PROBLEMS IN QUANTUM ELECTRONICS: Optical components for the analysis and formation of the transverse mode composition

NASA Astrophysics Data System (ADS)

Golub, M. A.; Sisakyan, I. N.; Soĭfer, V. A.; Uvarov, G. V.

1989-04-01

Theoretical and experimental investigations are reported of new mode optical components (elements) which are analogs of sinusoidal phase diffraction gratings with a variable modulation depth. Expressions are derived for nonlinear predistortion and depth of modulation, which are essential for effective operation of amplitude and phase mode optical components in devices used for analysis and formation of the transverse mode composition of coherent radiation. An estimate is obtained of the energy efficiency of phase and amplitude mode optical components, and a comparison is made with the results of an experimental investigation of a set of phase optical components matched to Gauss-Laguerre modes. It is shown that the improvement in the energy efficiency of phase mode components, compared with amplitude components, is the same as the improvement achieved using a phase diifraction grating, compared with amplitude grating with the same depth of modulation.

Optically phase-locked electronic speckle pattern interferometer system performance for vibration measurement in random displacement fields

NASA Astrophysics Data System (ADS)

Moran, Steve E.; Lugannani, Robert; Craig, Peter N.; Law, Robert L.

1989-02-01

An analysis is made of the performance of an optically phase-locked electronic speckle pattern interferometer in the presence of random noise displacements. Expressions for the phase-locked speckle contrast for single-frame imagery and the composite rms exposure for two sequentially subtracted frames are obtained in terms of the phase-locked composite and single-frame fringe functions. The noise fringe functions are evaluated for stationary, coherence-separable noise displacements obeying Gauss-Markov temporal statistics. The theoretical findings presented here are qualitatively supported by experimental results.

A study of the diffusional behavior of a two-phase metal matrix composite exposed to a high temperature environment

NASA Technical Reports Server (NTRS)

Tenney, D. R.

1974-01-01

The progress of diffusion-controlled filament-matrix interaction in a metal matrix composite where the filaments and matrix comprise a two-phase binary alloy system was studied by mathematically modeling compositional changes resulting from prolonged elevated temperature exposure. The analysis treats a finite, diffusion-controlled, two-phase moving-interface problem by means of a variable-grid finite-difference technique. The Ni-W system was selected as an example system. Modeling was carried out for the 1000 to 1200 C temperature range for unidirectional composites containing from 6 to 40 volume percent tungsten filaments in a Ni matrix. The results are displayed to show both the change in filament diameter and matrix composition as a function of exposure time. Compositional profiles produced between first and second nearest neighbor filaments were calculated by superposition of finite-difference solutions of the diffusion equations.

Experimental study and thermodynamic modeling of the Al–Co–Cr–Ni system

DOE PAGES

Gheno, Thomas; Liu, Xuan L.; Lindwall, Greta; ...

2015-09-21

In this study, a thermodynamic database for the Al–Co–Cr–Ni system is built via the Calphad method by extrapolating re-assessed ternary subsystems. A minimum number of quaternary parameters are included, which are optimized using experimental phase equilibrium data obtained by electron probe micro-analysis and x-ray diffraction analysis of NiCoCrAlY alloys spanning a wide compositional range, after annealing at 900 °C, 1100 °C and 1200 °C, and water quenching. These temperatures are relevant to oxidation and corrosion resistant MCrAlY coatings, where M corresponds to some combination of nickel and cobalt. Comparisons of calculated and measured phase compositions show excellent agreement for themore » β–γ equilibrium, and good agreement for three-phase β–γ–σ and β–γ–α equilibria. An extensive comparison with existing Ni-base databases (TCNI6, TTNI8, NIST) is presented in terms of phase compositions.« less

Fabrication and thermophysical property characterization of UN/U 3Si 2 composite fuel forms

DOE PAGES

White, Joshua Taylor; Travis, Austin William; Dunwoody, John Tyler; ...

2017-09-21

High uranium density composite fuels composed of UN and U 3Si 2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U 3Si 2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U 3Si 2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, andmore » thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. In conclusion, the impact of irradiation on thermal conductivity was also simulated for this class of composite materials.« less

Fabrication and thermophysical property characterization of UN/U 3Si 2 composite fuel forms

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

White, Joshua Taylor; Travis, Austin William; Dunwoody, John Tyler

High uranium density composite fuels composed of UN and U 3Si 2 have been fabricated using a liquid phase sintering route at temperatures between 1873 K and 1973 K and spanning compositions of 10 vol% to 40 vol% U 3Si 2. Microstructural analysis and phase characterization revealed the formation of an U-Si-N phase of unknown structure. Microcracking was observed in the U-Si portion of the composite microstructure that likely originates from the mismatched coefficient of thermal expansion between the UN and U 3Si 2 leading to stresses on heating and cooling of the composite. Thermal expansion coefficient, thermal diffusivity, andmore » thermal conductivity were characterized for each of the compositions as a function of temperature to 1673 K. Hysteresis is observed in the thermal diffusivity for the 20 vol% through 40 vol% specimens between room temperature and 1273 K, which is attributed to the microcracking in the U-Si phase. Thermal conductivity of the composites was modeled using the MOOSE framework based on the collected microstructure data. In conclusion, the impact of irradiation on thermal conductivity was also simulated for this class of composite materials.« less

Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1-x)TiO3/Cu Composite.

PubMed

Sheng, Jie; Wang, Lidong; Li, Shouwei; Yin, Benke; Liu, Xiangli; Fei, Wei-Dong

2016-06-03

The properties of metal matrix composites (MMCs) can be optimized effectively through adjusting the type or the volume fraction of reinforcement. Generally, the coefficient of thermal expansion (CTE) of MMCs can be reduced by increasing the volume fraction of the reinforcement with lower CTE than metal matrix. However, it is great challenge to fabricate low CTE MMCs with low reinforcement volume fraction because of the limitation of reinforcement CTEs. SrxBa1-xTiO3 (SBT) powder presents negative thermal expansion behavior during the phase transformation from tetragonal to cubic phase. Here, we demonstrate that the phase transformation of SBT can be utilized to reduce and design the thermal expansion properties of SBT particle-reinforced Cu (SBT/Cu) composite, and ultralow CTE can be obtained in SBT/Cu composite. The X-ray diffraction analysis on heating indicates that the temperature range of phase transformation is extended greatly, therefore, the low CTE can be achieved within wide temperature range. Landau-Devonshire theory study on the phase transformation behaviors of SBT particles in the composite indicates that thermal mismatch stress significantly affects the Curie temperature of SBT particles and the CTE of the composite. The results given in the present study provide a new approach to design the MMCs with low CTE.

Raman Study of Uncoated and p-BN/SiC-Coated Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites. Part 1; Distribution and Nanostructure of Different Phases

NASA Technical Reports Server (NTRS)

Gouadec, Gwenael; Colomban, Philippe; Bansal, Narottam P.

2000-01-01

Hi-Nicalon fiber reinforced celsian matrix composites were characterized by Raman spectroscopy and imaging, using several laser wavelengths. Composite #1 is reinforced by as-received fibers while coatings of p-BN and SiC protect the fibers in composite #2. The matrix contains traces of the hexagonal phase of celsian, which is concentrated in the neighborhood of fibers in composite #1. Some free silicon was evident in the coating of composite #2 which might involve a {BN + SiC yields BNC + Si} "reaction" at the p-BN/SiC interface. Careful analysis of C-C peaks revealed no abnormal degradation of the fiber core in the composites.

Influence of natural fibers on the phase transitions in high-density polyethylene composites using dynamic mechanical analysis

Treesearch

Mehdi Tajvidi; Robert H. Falk; John C. Hermanson; Colin Felton

2003-01-01

Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber....

Feasibility of using microencapsulated phase change materials as filler for improving low temperature performance of rubber sealing materials.

PubMed

Tiwari, Avinash; Shubin, Sergey N; Alcock, Ben; Freidin, Alexander B; Thorkildsen, Brede; Echtermeyer, Andreas T

2017-11-01

The feasibility of a novel composite rubber sealing material to improve sealing under transient cooling (in a so-called blowdown scenario) is investigated here. A composite of hydrogenated nitrile butadiene rubber (HNBR) filled with Micro Encapsulated Phase Change Materials (MEPCM) is described. The fillers contain phase change materials that release heat during the phase transformation from liquid to solid while cooling. This exotherm locally heats the rubber and may improve the function of the seal during a blowdown event. A representative HNBR-MEPCM composite was made and the critical thermal and mechanical properties were obtained by simulating the temperature distribution during a blowdown event. Simulations predict that the MEPCM composites can delay the temperature decrease in a region of the seal during the transient blowdown. A sensitivity analysis of material properties is also presented which highlights possible avenues of improvement of the MEPCMs for sealing applications.

The Effect of Film Composition on the Texture and Grain Size of CuInS2 Prepared by Spray Pyrolysis

NASA Technical Reports Server (NTRS)

Jin, Michael H.; Banger, Kulinder K.; Harris, Jerry D.; Hepp, Aloysius F.

2003-01-01

Ternary single-source precursors were used to deposit CuInS2 thin films using chemical spray pyrolysis. We investigated the effect of the film composition on texture, secondary phase formation, and grain size. As-grown films were most often In-rich. They became more (204/220)-oriented as indium concentration increased, and always contained a yet unidentified secondary phase. The (112)-prefened orientation became more pronounced as the film composition became more Cu-rich. The secondary phase was determined to be an In-rich compound based on composition analysis and Raman spectroscopy. In addition, as-grown Cu-rich (112)-oriented films did not exhibit the In-rich compound. Depositing a thin Cu layer prior to the growth of CuInS2 increased the maximum grain size from - 0.5 micron to - 1 micron, and prevented the formation of the In-rich secondary phase.

Crystal-Chemical Analysis Martian Minerals in Gale Crater

NASA Technical Reports Server (NTRS)

Morrison, S. M.; Downs, R. T.; Blake, D. F.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Yen, A. S.; Chipera, S. J.; Treiman, A. H.; Vaniman, D. T.;

Micromechanics of composites with shape memory alloy fibers in uniform thermal fields

NASA Technical Reports Server (NTRS)

Birman, Victor; Saravanos, Dimitris A.; Hopkins, Dale A.

1995-01-01

Analytical procedures are developed for a composite system consisting of shape memory alloy fibers within an elastic matrix subject to uniform temperature fluctuations. Micromechanics for the calculation of the equivalent properties of the composite are presented by extending the multi-cell model to incorporate shape memory alloy fibers. A three phase concentric cylinder model is developed for the analysis of local stresses which includes the fiber, the matrix, and the surrounding homogenized composite. The solution addresses the complexities induced by the nonlinear dependence of the in-situ martensite fraction of the fibers to the local stresses and temperature, and the local stresses developed from interactions between the fibers and matrix during the martensitic and reverse phase transformations. Results are presented for a nitinol/epoxy composite. The applications illustrate the response of the composite in isothermal longitudinal loading and unloading, and in temperature induced actuation. The local stresses developed in the composite under various stages of the martensitic and reverse phase transformation are also shown.

Analysis and comparison of biomass pyrolysis/gasification condensates: Final report

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

Elliott, D.C.

1986-06-01

This report provides results of chemical and physical analysis of condensates from eleven biomass gasification and pyrolysis systems. The samples were representative of the various reactor configurations being researched within the Department of Energy, Biomass Thermochemical Conversion program. The condensates included tar phases and aqueous phases. The analyses included gross compositional analysis (elemental analysis, ash, moisture), physical characterization (pour point, viscosity, density, heat of combustion, distillation), specific chemical analysis (gas chromatography/mass spectrometry, infrared spectrophotometry, proton and carbon-13 nuclear magnetic resonance spectrometry) and biological activity (Ames assay and mouse skin tumorigenicity tests). These results are the first step of a longermore » term program to determine the properties, handling requirements, and utility of the condensates recovered from biomass gasification and pyrolysis. The analytical data demonstrates the wide range of chemical composition of the organics recovered in the condensates and suggests a direct relationship between operating temperature and chemical composition of the condensates. A continuous pathway of thermal degradation of the tar components as a function of temperature is proposed. Variations in the chemical composition of the organic components in the tars are reflected in the physical properties of tars and phase stability in relation to water in the condensate. The biological activity appears to be limited to the tars produced at high temperatures. 56 refs., 25 figs., 21 tabs.« less

LOW ACTIVATION JOINING OF SIC/SIC COMPOSITES FOR FUSION APPLICATIONS: MODELING DUAL-PHASE MICROSTRUCTURES AND DISSIMILAR MATERIAL JOINTS

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

Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

2016-03-31

Finite element continuum damage models (FE-CDM) have been developed to simulate and model dual-phase joints and cracked joints for improved analysis of SiC materials in nuclear environments. This report extends the analysis from the last reporting cycle by including results from dual-phase models and from cracked joint models.

Additive Manufacturing of Reactive In Situ Zr Based Ultra-High Temperature Ceramic Composites

NASA Astrophysics Data System (ADS)

Sahasrabudhe, Himanshu; Bandyopadhyay, Amit

2016-03-01

Reactive in situ multi-material additive manufacturing of ZrB2-based ultra-high-temperature ceramics in a Zr metal matrix was demonstrated using LENS™. Sound metallurgical bonding was achieved between the Zr metal and Zr-BN composites with Ti6Al4V substrate. Though the feedstock Zr power had α phase, LENS™ processing of the Zr powder and Zr-BN premix powder mixture led to the formation of some β phase of Zr. Microstructure of the Zr-BN composite showed primary grains of zirconium diboride phase in zirconium metal matrix. The presence of ZrB2 ceramic phase was confirmed by X-ray diffraction (XRD) analysis. Hardness of pure Zr was measured as 280 ± 12 HV and, by increasing the BN content in the feedstock, the hardness was found to increase. In Zr-5%BN composite, the hardness was 421 ± 10 HV and the same for Zr-10%BN composite was 562 ± 10 HV. It is envisioned that such multi-materials additive manufacturing will enable products in the future that cannot be manufactured using traditional approaches particularly in the areas of high-temperature metal-ceramic composites with compositional and functional gradation.

Comparison of dissimilarity measures for cluster analysis of X-ray diffraction data from combinatorial libraries

NASA Astrophysics Data System (ADS)

Iwasaki, Yuma; Kusne, A. Gilad; Takeuchi, Ichiro

2017-12-01

Machine learning techniques have proven invaluable to manage the ever growing volume of materials research data produced as developments continue in high-throughput materials simulation, fabrication, and characterization. In particular, machine learning techniques have been demonstrated for their utility in rapidly and automatically identifying potential composition-phase maps from structural data characterization of composition spread libraries, enabling rapid materials fabrication-structure-property analysis and functional materials discovery. A key issue in development of an automated phase-diagram determination method is the choice of dissimilarity measure, or kernel function. The desired measure reduces the impact of confounding structural data issues on analysis performance. The issues include peak height changes and peak shifting due to lattice constant change as a function of composition. In this work, we investigate the choice of dissimilarity measure in X-ray diffraction-based structure analysis and the choice of measure's performance impact on automatic composition-phase map determination. Nine dissimilarity measures are investigated for their impact in analyzing X-ray diffraction patterns for a Fe-Co-Ni ternary alloy composition spread. The cosine, Pearson correlation coefficient, and Jensen-Shannon divergence measures are shown to provide the best performance in the presence of peak height change and peak shifting (due to lattice constant change) when the magnitude of peak shifting is unknown. With prior knowledge of the maximum peak shifting, dynamic time warping in a normalized constrained mode provides the best performance. This work also serves to demonstrate a strategy for rapid analysis of a large number of X-ray diffraction patterns in general beyond data from combinatorial libraries.

Studies on magnetocapacitance, dielectric, ferroelectric, and magnetic properties of microwave sintered (1-x) (Ba0.8Sr0.2TiO3) - x (Co0.9Ni0.1Fe2O4) multiferroic composite

NASA Astrophysics Data System (ADS)

Mane, Sagar M.; Tirmali, Pravin M.; Ranjit, Bhakti; Khan, Madiha; Khan, Nargis; Tarale, Arjun N.; Kulkarni, Shrinivas B.

2018-07-01

Present paper reports the synthesis of multiferroic composite (1-x) [Ba0.8Sr0.2Ti)O3]-x[Co0.9Ni0.1Fe2O4] were x = 0.1, 0.2, 0.3 and 0.4. Both phases of the composite i.e. ferroelectric (BST) and ferrite (CNFO) are synthesized via hydroxide co-precipitation method followed by microwave sintering technique at 1100 °C. These composites were characterized for their structural, microstructural, dielectric analysis, magnetodielectric (MD) effect and ferroelectric properties. Presence of both the phases ferroelectric (BST) and ferromagnetic (CNFO) are confirmed by the x-ray diffraction and scanning electron microscopic analysis. Maxwell-Wagner type dielectric dispersion is observed in frequency dependent dielectric measurement. Temperature-dependent dielectric properties were measured from 25 °C to 500 °C at various applied frequencies. Ferroelectric behavior in the composites was confirmed by the polarization vs. Electric field analysis. The magnetodielectric effect was studied in the presence of applied magnetic field from 0 to 1 Tesla. Magnetocapacitance (%) increases with increase in the ferrite concentration in the ferroelectric phase. The maximum percentage of magnetocapacitance is observed in 60BST-40CNFO composite which is MC = 30% at the frequency 1 KHz with the applied magnetic field is 1-Tesla. Room temperature magnetic hysteresis loops show an increase in saturation magnetization (Ms) with an increase in ferrite concentration.

MAC/GMC Code Enhanced for Coupled Electromagnetothermoelastic Analysis of Smart Composites

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.; Aboudi, Jacob

2002-01-01

Intelligent materials are those that exhibit coupling between their electromagnetic response and their thermomechanical response. This coupling allows smart materials to react mechanically (e.g., an induced displacement) to applied electrical or magnetic fields (for instance). These materials find many important applications in sensors, actuators, and transducers. Recently interest has arisen in the development of smart composites that are formed via the combination of two or more phases, one or more of which is a smart material. To design with and utilize smart composites, designers need theories that predict the coupled smart behavior of these materials from the electromagnetothermoelastic properties of the individual phases. The micromechanics model known as the generalized method of cells (GMC) has recently been extended to provide this important capability. This coupled electromagnetothermoelastic theory has recently been incorporated within NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC). This software package is user friendly and has many additional features that render it useful as a design and analysis tool for composite materials in general, and with its new capabilities, for smart composites as well.

Cutting Modeling of Hybrid CFRP/Ti Composite with Induced Damage Analysis

PubMed Central

Xu, Jinyang; El Mansori, Mohamed

2016-01-01

In hybrid carbon fiber reinforced polymer (CFRP)/Ti machining, the bi-material interface is the weakest region vulnerable to severe damage formation when the tool cutting from one phase to another phase and vice versa. The interface delamination as well as the composite-phase damage is the most serious failure dominating the bi-material machining. In this paper, an original finite element (FE) model was developed to inspect the key mechanisms governing the induced damage formation when cutting this multi-phase material. The hybrid composite model was constructed by establishing three disparate physical constituents, i.e., the Ti phase, the interface, and the CFRP phase. Different constitutive laws and damage criteria were implemented to build up the entire cutting behavior of the bi-material system. The developed orthogonal cutting (OC) model aims to characterize the dynamic mechanisms of interface delamination formation and the affected interface zone (AIZ). Special focus was made on the quantitative analyses of the parametric effects on the interface delamination and composite-phase damage. The numerical results highlighted the pivotal role of AIZ in affecting the formation of interface delamination, and the significant impacts of feed rate and cutting speed on delamination extent and fiber/matrix failure. PMID:28787824

The influence of voxel size on atom probe tomography data.

PubMed

Torres, K L; Daniil, M; Willard, M A; Thompson, G B

2011-05-01

A methodology for determining the optimal voxel size for phase thresholding in nanostructured materials was developed using an atom simulator and a model system of a fixed two-phase composition and volume fraction. The voxel size range was banded by the atom count within each voxel. Some voxel edge lengths were found to be too large, resulting in an averaging of compositional fluctuations; others were too small with concomitant decreases in the signal-to-noise ratio for phase identification. The simulated methodology was then applied to the more complex experimentally determined data set collected from a (Co(0.95)Fe(0.05))(88)Zr(6)Hf(1)B(4)Cu(1) two-phase nanocomposite alloy to validate the approach. In this alloy, Zr and Hf segregated to an intergranular amorphous phase while Fe preferentially segregated to a crystalline phase during the isothermal annealing step that promoted primary crystallization. The atom probe data analysis of the volume fraction was compared to transmission electron microscopy (TEM) dark-field imaging analysis and a lever rule analysis of the volume fraction within the amorphous and crystalline phases of the ribbon. Copyright © 2011 Elsevier B.V. All rights reserved.

[Revisiting the chemical diversity in prostatic calculi: a SEM and FT-IR investigation].

PubMed

Dessombz, A; Méria, P; Bazin, D; Foy, E; Rouzière, S; Weil, R; Daudon, M

2011-12-01

Revisiting the chemical diversity of the crystalline phases of prostatic calculi by means of SEM and FT-IR analysis. A set of 32 prostatic calculi has been studied by FT-IR and SEM. FT-IR analysis has determined the chemical composition of each prostatic calculus and the SEM observation has described the morphology of the calculi surfaces and layers. Infrared analysis revealed that 90.7% of the stones were mainly composed of calcium phosphates. However, several mineral phases previously not reported in prostatic calculi were observed, as brushite or octocalcium phosphate pentahydrate. Prostatic calculi exhibited a diversity of crystalline composition and morphology. As previously reported for urinary calculi, relationships between composition and morphology of prostatic stones and étiopathogenic conditions could be of interest in clinical practice. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1–x)TiO3/Cu Composite

PubMed Central

Sheng, Jie; Wang, Lidong; Li, Shouwei; Yin, Benke; Liu, Xiangli; Fei, Wei-Dong

2016-01-01

The properties of metal matrix composites (MMCs) can be optimized effectively through adjusting the type or the volume fraction of reinforcement. Generally, the coefficient of thermal expansion (CTE) of MMCs can be reduced by increasing the volume fraction of the reinforcement with lower CTE than metal matrix. However, it is great challenge to fabricate low CTE MMCs with low reinforcement volume fraction because of the limitation of reinforcement CTEs. SrxBa1−xTiO3 (SBT) powder presents negative thermal expansion behavior during the phase transformation from tetragonal to cubic phase. Here, we demonstrate that the phase transformation of SBT can be utilized to reduce and design the thermal expansion properties of SBT particle-reinforced Cu (SBT/Cu) composite, and ultralow CTE can be obtained in SBT/Cu composite. The X-ray diffraction analysis on heating indicates that the temperature range of phase transformation is extended greatly, therefore, the low CTE can be achieved within wide temperature range. Landau-Devonshire theory study on the phase transformation behaviors of SBT particles in the composite indicates that thermal mismatch stress significantly affects the Curie temperature of SBT particles and the CTE of the composite. The results given in the present study provide a new approach to design the MMCs with low CTE. PMID:27255420

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-08-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2018-06-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Enhanced electrochemical performance of a ZnO-MnO composite as an anode material for lithium ion batteries.

PubMed

Song, Min Seob; Nahm, Sahn; Cho, Won Il; Lee, Chongmok

2015-09-28

A ZnO-MnO composite was synthesized using a simple solvothermal method combined with a high-temperature treatment. To observe the phase change during the heating process, in situ high-temperature XRD analysis was performed under vacuum conditions. The results indicated that ZnMn2O4 transformed into the ZnO-MnO composite phase starting from 500 °C and that this composite structure was retained until 700 °C. The electrochemical performances of the ZnO-MnO composite electrode were evaluated through galvanostatic discharge-charge tests and cyclic voltammetry analysis. Its initial coulombic efficiency was significantly improved to 68.3% compared to that of ZnMn2O4 at 54.7%. Furthermore, the ZnO-MnO composite exhibited improved cycling performance and enhanced rate capability compared with untreated ZnMn2O4. To clarify the discharge-charge mechanism of the ZnO-MnO composite electrode, the structural changes during the charge and discharge processes were also investigated using ex situ XRD and TEM.

Analytical electron microscopy in mineralogy; exsolved phases in pyroxenes

USGS Publications Warehouse

Nord, G.L.

1982-01-01

Analytical scanning transmission electron microscopy has been successfully used to characterize the structure and composition of lamellar exsolution products in pyroxenes. At operating voltages of 100 and 200 keV, microanalytical techniques of x-ray energy analysis, convergent-beam electron diffraction, and lattice imaging have been used to chemically and structurally characterize exsolution lamellae only a few unit cells wide. Quantitative X-ray energy analysis using ratios of peak intensities has been adopted for the U.S. Geological Survey AEM in order to study the compositions of exsolved phases and changes in compositional profiles as a function of time and temperature. The quantitative analysis procedure involves 1) removal of instrument-induced background, 2) reduction of contamination, and 3) measurement of correction factors obtained from a wide range of standard compositions. The peak-ratio technique requires that the specimen thickness at the point of analysis be thin enough to make absorption corrections unnecessary (i.e., to satisfy the "thin-foil criteria"). In pyroxenes, the calculated "maximum thicknesses" range from 130 to 1400 nm for the ratios Mg/Si, Fe/Si, and Ca/Si; these "maximum thicknesses" have been contoured in pyroxene composition space as a guide during analysis. Analytical spatial resolutions of 50-100 nm have been achieved in AEM at 200 keV from the composition-profile studies, and analytical reproducibility in AEM from homogeneous pyroxene standards is ?? 1.5 mol% endmember. ?? 1982.

Thermal conductivity of hybrid short fiber composites

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

Dunn, M.L.; Taya, M.; Hatta, H.

1993-01-01

A combined analytical/experimental study has been undertaken to investigate the effective thermal conductivity of hybrid composite materials. The analysis utilizes the equivalent inclusion approach for steady state heat conduction (Hatta and Taya, 1986) through which the interaction between the various reinforcing phases at finite concentrations is approximated by the Mori-Tanaka (1973) mean field approach. The multiple reinforcing phases of the composite are modeled as ellipsoidal in shape and thus can simulate a wide range of microstructural geometries ranging from thin platelet to continuous fiber reinforcement. The case when one phase of the composite is penny-shaped microcracks is studied in detail.more » Multiphase composites consisting of a Kerimid matrix and Al2O3 short fibers and Si3N4 whiskers were fabricated and, after a careful study of their microstructure, their thermal conductivities were measured. Analytical predictions are shown to be in good agreement with experimental results obtained for the Al2O3/Si3N4/Kerimid short fiber composites. 26 refs.« less

Structural and magnetic properties of nanocomposite iron-containing SiCxNy films

NASA Astrophysics Data System (ADS)

Pushkarev, R. V.; Fainer, N. I.; Maurya, K. K.

2017-02-01

New ferromagnetic films with composition SiCxNyFez were synthesized using chemical vapor deposition technique. Films were deposited using ferrocene, 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and hydrogen gaseous mixture. Chemical and phase composition of the films were studied by FTIR, Raman spectroscopy and X-ray diffraction with grazing incidence (GI-XRD). FTIR spectra analysis confirmed the existence of Si-C and Si-N bonds. Graphite inclusions and amorphous carbon were determined by Raman spectra analysis. The surface of the SiCxNyFez films studied by SEM is covered by nanocrystallites of iron oxide Fe3O4 phase. The main purpose of GI-XRD analysis is to describe the layered structure of the films in detail. It was shown by GI-XRD study, that phase composition of the SiCxNyFez films varies from iron oxide Fe3O4 to iron silicide Fe3Si and silicon carbide SiC with the deposition temperature growing. It was established, that SiCxNyFez films are perspective for application in the spintronic field.

Melting and Vaporization of the 1223 Phase in the System (Tl-Pb-Ba-Sr-Ca-Cu-O)

PubMed Central

Cook, L. P.; Wong-Ng, W.; Paranthaman, P.

1996-01-01

The melting and vaporization of the 1223 [(Tl,Pb):(Ba,Sr):Ca:Cu] oxide phase in the system (Tl-Pb-Ba-Sr-Ca-Cu-O) have been investigated using a combination of dynamic methods (differential thermal analysis, thermogravimetry, effusion) and post-quenching characterization techniques (powder x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectrometry). Vaporization rates, thermal events, and melt compositions were followed as a function of thallia loss from a 1223 stoichiometry. Melting and vaporization equilibria of the 1223 phase are complex, with as many as seven phases participating simultaneously. At a total pressure of 0.1 MPa the 1223 phase was found to melt completely at (980 ± 5) °C in oxygen, at a thallia partial pressure (pTl2O) of (4.6 ± 0.5) kPa, where the quoted uncertainties are standard uncertainties, i.e., 1 estimated standard deviation. The melting reaction involves five other solids and a liquid, nominally as follows: 1223→1212+(Ca,Sr)2CuO3+(Sr,Ca)CuO2+BaPbO3+(Ca,Sr)O+Liquid Stoichiometries of the participating phases have been determined from microchemical analysis, and substantial elemental substitution on the 1212 and 1223 crystallographic sites is indicated. The 1223 phase occurs in equilibrium with liquids from its melting point down to at least 935 °C. The composition of the lowest melting liquid detected for the bulk compositions of this study has been measured using microchemical analysis. Applications to the processing of superconducting wires and tapes are discussed. PMID:27805086

Combinatorial atmospheric pressure chemical vapor deposition of graded TiO₂-VO₂ mixed-phase composites and their dual functional property as self-cleaning and photochromic window coatings.

PubMed

Wilkinson, Mia; Kafizas, Andreas; Bawaked, Salem M; Obaid, Abdullah Y; Al-Thabaiti, Shaeel A; Basahel, Sulaiman N; Carmalt, Claire J; Parkin, Ivan P

2013-06-10

A combinatorial film with a phase gradient from V:TiO₂ (V: Ti ≥ 0.08), through a range of TiO₂-VO₂ composites, to a vanadium-rich composite (V: Ti = 1.81) was grown by combinatorial atmospheric pressure chemical vapor deposition (cAPCVD). The film was grown from the reaction of TiCl₄, VCl₄, ethyl acetate (EtAc), and H₂O at 550 °C on glass. The gradient in gas mixtures across the reactor induced compositional film growth, producing a single film with numerous phases and compositions at different positions. Seventeen unique positions distributed evenly along a central horizontal strip were investigated. The physical properties were characterized by wavelength dispersive X-ray (WDX) analysis, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV-visible spectroscopy. The functional properties examined included the degree of photoinduced hydrophilicity (PIH), UVC-photocatalysis, and thermochromism. Superhydrophilic contact angles could be achieved at all positions, even within a highly VO₂-rich composite (V: Ti = 1.81). A maximum level of UVC photocatalysis was observed at a position bordering the solubility limit of V:TiO₂ (V: Ti ≈ 0.21) and fragmentation into a mixed-phase composite. Within the mixed-phase TiO₂: VO₂ composition region (V: Ti = 1.09 to 1.81) a decrease in the semiconductor-to-metal transition temperature of VO₂ from 68 to 51 °C was observed.

The Preparation and Characterization of INTEC HAW Phase I Composition Variation Study Glasses

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

Musick, C. A.; Peeler, D. K.; Piepel, G. F.

1999-03-01

A glass composition variation study (CVS) is in progress to define formulations for the vitrification of high activity waste (HAW) proposed to be separated from dissolved calcine stored at the Idaho National Engineering and Environmental Laboratory (INEEL). Estimates of calcine and HAW compositions prepared in FY97 were used to define test matrix glasses. The HAW composition is of particular interest because high aluminum, zirconium, phosphorous and potassium, and low iron and sodium content places it outside the realm of vitrification experience in the Department of Energy (DOE) complex. Through application of statistical techniques, a test matrix was defined for Phasemore » 1 of the CVS. From this matrix, formulations were systematically selected for preparation and characterization with respect to homogeneity, viscosity, liquidus temperature (TL), and leaching response when subjected to the Product Consistency Test (PCT). Based on the properties determined, certain formulations appear suitable for further development including use in planning Phase 2 of the study. It is recommended that glasses to be investigated in Phase 2 be limited to 3-5 wt % phosphate. The results of characterizing the Phase 1 glasses are presented in this document. A full analysis of the composition-property relationships of glasses being developed for immobilizing HAWs will be performing at the completion of CVS phases. This analysis will be needed for the optimization of the glass formulations of vitrifying HAW. Contributions were made to this document by personnel working at the INEEL, Pacific Northwest National Laboratories (PNNL), and the Savannah River Technology Center (SRTC).« less

Phase diagram of the Pr-Mn-O system in composition-temperature-oxygen pressure coordinates

NASA Astrophysics Data System (ADS)

Vedmid', L. B.; Yankin, A. M.; Fedorova, O. M.; Kozin, V. M.

2016-05-01

The phase relations in the Pr-Mn-O system were studied by the static method at lowered oxygen pressure in combination with thermal analysis and high-temperature X-ray diffraction. The equilibrium oxygen pressure in dissociation of PrMn2O5 and PrMnO3 was measured, and the thermodynamic characteristics of formation of these compounds from elements were calculated. The P- T- x phase diagram of the Pr-Mn-O system was constructed in the "composition-oxygen pressure-temperature" coordinates.

The solid-solution region for the langasite-type Ca3TaGa3Si2O14 crystal as determined by a lever rule

NASA Astrophysics Data System (ADS)

Zhao, Hengyu; Uda, Satoshi; Maeda, Kensaku; Nozawa, Jun; Koizumi, Haruhiko; Fujiwara, Kozo

2015-04-01

A lever rule was applied to data concerning the compositions and proportions of secondary phases coexisting with a Ca3TaGa3Si2O14 (CTGS) matrix to determine the boundary compositions of the solid-solution region for CTGS at 1320 °C, as a means of ascertaining the solid-solution for the langasite-type phase in the quaternary CaO-Ta2O5-Ga2O3-SiO2 system. The compositions and proportions of secondary phases were assessed by electron probe micro-analysis as well as through back-scattered electron images. The experimental results showed that the narrow solid-solution region for CTGS is located in a Ta-poor, Ga-poor and Si-rich region relative to its stoichiometric composition.

Fatigue damage evaluation of short fiber CFRP based on phase information of thermoelastic temperature change

NASA Astrophysics Data System (ADS)

Sakagami, Takahide; Shiozawa, Daiki; Nakamura, Yu; Nonaka, Shinichi; Hamada, Kenichi

2017-05-01

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to the evaluation of fatigue damage in short carbon fiber composites. The distributions of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damages was detected from distributions of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was clearly detected than ever by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the nature that carbon fiber show opposite phase thermoelastic temperature change.

Low Activation Joining of SiC/SiC Composites for Fusion Applications: Thermomechanical Modeling of Dual-Phase Microstructures and Dissimilar Material Joints

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

Nguyen, Ba Nghiep; Henager, Charles H.; Kurtz, Richard J.

2016-09-30

Finite element (FE) continuum damage mechanics (CDM) models have been developed to simulate and model dual-phase joints and cracked joints for improved analysis of SiC materials in nuclear environments. This report extends the analysis from the last reporting cycle by including preliminary thermomechanical analyses of cracked joints and implementation of dual-phase damage models.

IR Spectroscopy and X-Ray Phase Analysis of the Chemical Composition of Gallstones

NASA Astrophysics Data System (ADS)

Pichugina, A. A.; Tsyro, L. V.; Unger, F. G.

2018-01-01

The composition of the inorganic and organic parts of gallstones was investigated by x-ray phase analysis and IR spectroscopy. Cholesterol, bilirubin, calcium bilirubinate, calcium carbonate, and calcium hydrogen phosphate are all found in gallstones. The major component is cholesterol. A gallstone was separated into layers and the inorganic part was separated out by annealing. Inorganic compounds were found to predominate in the outer layer of the gallstone, which is related to the mechanism of its formation. The inorganic part contains calcium carbonate, present in both the calcite and waterite modifications.

Effect of Heat Treatment on The Crystal Structur, Electrical Conductivity and Surface of Ba1.5Sr0.5Fe2O5 Composite

NASA Astrophysics Data System (ADS)

Purwanto, P.; Adi, WA; Yunasfi

2017-05-01

The Composite of Ba1,5Sr0,5Fe2O5 has been synthesized by using powder metallurgy technique. The Ba1.5Sr0.5Fe2O5 were prepared from BaCO3, SrCO3 and Fe2O3 raw materials with a specific weight ratio. The three materials were synthesized by powder metallurgy under heat treatment at 800 °C, 900 °C, and 1000 °C for 5 hours. All the three samples were characterized by using X-ray Diffraction (XRD) to determine the crystal structure and crystal size, LCR meter to determine the conductivity, and Scanning Electron Microscope (SEM) to observe the morphological of the composites. The phase analysis result showed that the composite consists of several minor phases such as BaO2, SrO2, and Fe2O3. The Crystal size of composite Ba1.5Sr0.5Fe2O5 decreased while increases the strain of crystal with increasing of sintering temperature. The crystal size of the Ba1.5Sr0.5Fe2O5 composite is 3.55 nm to 7.23 nm and value of strain is 8.47% until 3.90%. Based on the conductivity measurement, it was obtained that the conductivity of the Ba1.5Sr0.5Fe2O5 composite decreased with increasing sintering temperature. It was also noticed that the conductivity increased with increasing of frequency. The conductivity ranged from 6.619×10-7 S/cm to 65.659×10-7 S/cm. The energy dispersive spectroscopy (EDS) analysis showed that several dominant elements were a good agreement with the phase analysis.

Phase study of SiO2-ZrO2 composites prepared from polymorphic combination of starting powders via a ball-milling followed by calcination

NASA Astrophysics Data System (ADS)

Musyarofah; Nurlaila, R.; Muwwaqor, N. F.; Saukani, M.; Kuswoyo, A.; Triwikantoro; Pratapa, S.

2017-04-01

The effects of SiO2-ZrO2 polymorphic combinations as starting powders and calcination temperature on phase composition of the SiO2-ZrO2 composites were studied. Stoichiometric (1:1 mol%) mixtures of the SiO2-ZrO2 composites were mechanically activated using a ball-milling for 5 h followed by calcinations at 1000, 1100 and 1200 °C for 3 h. The composites used in the present study were a-SiO2+ a-ZrO2, a-SiO2+ t-ZrO2, c-SiO2+ a-ZrO2 and c-SiO2+ t-ZrO2 which were symbolized by AA, AT, CA and CT, respectively. Prefixes a, t and c denote amorphous, tetragonal and cristobalite, respectively. The phase composition was determined by Rietveld analysis of X-ray diffraction (XRD) data using Rietica software. The identified phases for all calcined samples were a combination among t-ZrO2, c-SiO2, m-ZrO2 and zircon (ZrSiO4). Amorphous zirconia formed a transient tetragonal zirconia phase during heating, which reacted with silica to form zircon. The zircon phase was not found to form even at 1200 °C in the AT and CT mixtures and at 1100 °C in the CA mixture. The AA mixture in particular crystallized to form zircon at a lower temperature with more composition fraction than the others, ca 82.9 (14) mol%.

Study of the effects of heat-treatment of hydroxyapatite synthesized in gelatin matrix

NASA Astrophysics Data System (ADS)

Zaits, A. V.; Golovanova, O. A.; Kuimova, M. V.

2017-01-01

In the study, the isothermal thermogravimetric analysis (TGA) of hydroxyapatite synthesized in gelatin matrix (HAG) has been performed. 3 wt.% HAG samples were synthesized from the solution simulating the human extracellular fluid (SBF). X-ray diffraction and IR spectroscopy were used to determine the composition. During the experiment, increase in the calcination temperature up to 200°C-800°C was found to cause weight loss. The study of phase composition revealed that heat treatment does not affect the phase composition of the solid phase, which is composed of hydroxylapatite (HA). The prepared HAG (3 wt.% gelatin) samples are shown to have low thermal stability; the degradation of the samples occurs at 400° C.

Study of the effects of heat-treatment of hydroxyapatite synthesized in gelatin matrix

NASA Astrophysics Data System (ADS)

Zaits, A. V.; Golovanova, O. A.; Kuimova, M. V.

2017-01-01

In the study, the isothermal thermogravimetric analysis (TGA) of hydroxyapatite synthesized in gelatin matrix (HAG) has been performed. 3 wt.% HAG samples were synthesized from the solution simulating the human extracellular fluid (SBF). X-ray diffraction and IR spectroscopy were used to determine the composition. During the experiment, increase in the calcination temperature up to 200°C-800°C was found to cause weight loss. The study of phase composition revealed that heat treatment does not affect the phase composition of the solid phase, which is composed of hydroxylapatite (HA). The prepared HAG (3 wt.% gelatin) samples are shown to have low thermal stability; the degradation of the samples occurs at 400°C.

DC conductivity and magnetic properties of piezoelectric-piezomagnetic composite system

NASA Astrophysics Data System (ADS)

Hemeda, O. M.; Tawfik, A.; A-Al-Sharif; Amer, M. A.; Kamal, B. M.; El Refaay, D. E.; Bououdina, M.

2012-11-01

A series of composites (1-x) (Ni0.8Zn0.2Fe2O4)+x (BaTiO3), where x=0%, 20%, 40%, 60%, 80% and 100% BT content, have been prepared by the standard ceramic technique, then sintered at 1200 °C for 8 h. X-ray diffraction analysis shows that the prepared composites consist of two phases, ferrimagnetic and ferroelectric. DC electrical resistivity, thermoelectric power, charge carriers concentration and charge carrier mobility have been studied at different temperatures. It was found that the DC electrical conductivity increases with increasing BT content. The values of the thermoelectric power were positive and negative for the composites indicating that there are two conduction mechanisms, hopping and band conduction, respectively. Using the values of DC electrical conductivity and thermoelectric power, the values of charge carrier mobility and the charge carrier concentration were calculated. Magnetic measurements (hysteresis loop and magnetic permeability) show that the magnetization decreases by increasing BT content. M-H loop of pure Ni0.6 Zn0.4 Fe2O4 composite indicates that it is paramagnetic at room temperature and that the magnetization is diluted by increasing the BT content in the composite system. The value of magnetoelectric coefficient for the composites decreases by increasing BT content for all the compositions except for 40% BT content, which may be due to the low resistivity of magnetic phase compared with the BT phase that causes a leakage of induced charges on the piezoelectric phase. Since both ferroelectric and magnetic phases preserve their basic properties in the bulk composite, the present BT-NZF composite are potential candidates for applications as pollution sensors and electromagnetic waves.

Structural, microstructural and thermal analysis of U-(6-x)Zr-xNb alloys (x = 0, 2, 4, 6)

NASA Astrophysics Data System (ADS)

Kaity, Santu; Banerjee, Joydipta; Parida, S. C.; Bhasin, Vivek

2018-06-01

Uranium-rich U-Zr-Nb alloy is considered as a good alternative fuel for fast reactors from the perspective of excellent dimensional stability and desired thermo-physical properties to achieve higher burnup. Detailed investigations related to the structural and microstructural characterization, thermal expansion, phase transformation, microhardness were carried out on U-6Zr, U-4Zr-2Nb, U-2Zr-4Nb and U-6Nb alloys (composition in wt%) where the total amount of alloying elements was restricted to 6 wt%. Structural, microstructural and thermal analysis studies revealed that these alloys undergo a series of transformations from high temperature bcc γ-phase to a variety of equilibrium and intermediate phases depending upon alloy composition, cooling rate and quenching. The structural analysis was carried out by Rietveld refinement. The data of U-Nb and U-Zr-Nb alloys have been highlighted and compared with binary U-Zr alloy.

Boron Carbide Aluminum Cermets for External Pressure Housing Applications

DTIC Science & Technology

1992-09-01

CHEMISTRY AND MICROSTRUCTURES OF THE B4C/Al SYSTEM ......................................... 4 3.2 MECHANICAL PROPERTIES OF B4C/AI COMPOSITES ....... 10...TABLES 1. Phase chemistry of B4C/A1 composites as a function of baking temperature (by stereology) .................. ...... 10 2. Summary of the...diffractometer using CuKo radiation and a scan rate of 2° per minute. The chemistry of all phases was determined from electron microprobe analysis of

Polydimethylsiloxane-based Self healing Composite and Coating Materials

DTIC Science & Technology

2006-01-01

TGA thermogravimetric analysis TDCB tapered double cantilever beam RH relative humidity DMDN-Sn dimethyldineodacanoate tin DBBE-Sn di-n-butyl bis(2...properties of micro-capsules by thermogravimetric analysis (TGA). As shown in figure 2.17, no weight change occurred up to the boiling point of...Elemental analysis of separated prepolymer phase and control samples. ..............24 Table 2.4: The size values of phase separated PDMS droplets

Analysis of Košice Meteorite by Mössbauer Spectroscopy

NASA Astrophysics Data System (ADS)

Sitek, Jozef; Dekan, Július; Sedlačková, Katarína

2016-07-01

The 57Fe Mössbauer spectroscopy method was used to investigate iron-containing compounds in town Košice meteorite fallen on the territory of Slovakia in February 2010. The results showed that the Mössbauer spectra consisted of magnetic and non-magnetic components related to different iron-bearing phases. The non-magnetic phase includes olivine, pyroxene and traces of Fe3+ phase and the magnetic component comprises troilite (FeS) and iron-rich Fe-Ni alloy with hyperfine magnetic field typical for kamacite. Samples from meteorite were obtained in powder from different depths to inspect its heterogeneous composition. The content of kamacite increases to the detriment of troilite from the surface toward the centre of the sample. Measurements at liquid nitrogen temperature confirmed phase composition of investigated meteorite. Main constituent elements of studied samples were also determined by X-ray fluorescence analysis.

Effect of acidity on the citrate-nitrate combustion synthesis of alumina-zirconia composite powder

NASA Astrophysics Data System (ADS)

Chandradass, J.; Kim, Ki Hyeon

2009-12-01

Alumina-zirconia composite powders were produced by sol-gel autocombustion. 20 wt.% ZrO2-Al2O3 mixture precursor solutions were chelated by citric acid ions at different pH. DTA analysis shows sluggish decomposition at low pH, whereas there was rapid decomposition at high pH = 9. XRD patterns of the calcined powders showed that well crystallized powder with 100 % tetragonal phase and α-alumina phase is produced when pH = 0.58 (without ammonia addition). TEM characterization of composite powders revealed homogenous distribution of nanosized zirconia particles in the alumina matrix. FTIR analysis shows peaks at 590 cm-1 and 454 cm-1, which are identified as the characteristic absorption bands of Zr-O and Al-O.

Membrane Bending Moduli of Coexisting Liquid Phases Containing Transmembrane Peptide.

PubMed

Usery, Rebecca D; Enoki, Thais A; Wickramasinghe, Sanjula P; Nguyen, V P; Ackerman, David G; Greathouse, Denise V; Koeppe, Roger E; Barrera, Francisco N; Feigenson, Gerald W

2018-05-08

A number of highly curved membranes in vivo, such as epithelial cell microvilli, have the relatively high sphingolipid content associated with "raft-like" composition. Given the much lower bending energy measured for bilayers with "nonraft" low sphingomyelin and low cholesterol content, observing high curvature for presumably more rigid compositions seems counterintuitive. To understand this behavior, we measured membrane rigidity by fluctuation analysis of giant unilamellar vesicles. We found that including a transmembrane helical GWALP peptide increases the membrane bending modulus of the liquid-disordered (Ld) phase. We observed this increase at both low-cholesterol fraction and higher, more physiological cholesterol fraction. We find that simplified, commonly used Ld and liquid-ordered (Lo) phases are not representative of those that coexist. When Ld and Lo phases coexist, GWALP peptide favors the Ld phase with a partition coefficient of 3-10 depending on mixture composition. In model membranes at high cholesterol fractions, Ld phases with GWALP have greater bending moduli than the Lo phase that would coexist. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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

Xiang, N. B.; Kong, D. F., E-mail: nanbin@ynao.ac.cn

The Physikalisch Meteorologisches Observatorium Davos total solar irradiance (TSI), Active Cavity Radiometer Irradiance Monitoring TSI, and Royal Meteorological Institute of Belgium TSI are three typical TSI composites. Magnetic Plage Strength Index (MPSI) and Mount Wilson Sunspot Index (MWSI) should indicate the weak and strong magnetic field activity on the solar full disk, respectively. Cross-correlation (CC) analysis of MWSI with three TSI composites shows that TSI should be weakly correlated with MWSI, and not be in phase with MWSI at timescales of solar cycles. The wavelet coherence (WTC) and partial wavelet coherence (PWC) of TSI with MWSI indicate that the inter-solar-cyclemore » variation of TSI is also not related to solar strong magnetic field activity, which is represented by MWSI. However, CC analysis of MPSI with three TSI composites indicates that TSI should be moderately correlated and accurately in phase with MPSI at timescales of solar cycles, and that the statistical significance test indicates that the correlation coefficient of three TSI composites with MPSI is statistically significantly higher than that of three TSI composites with MWSI. Furthermore, the cross wavelet transform (XWT) and WTC of TSI with MPSI show that the TSI is highly related and actually in phase with MPSI at a timescale of a solar cycle as well. Consequently, the CC analysis, XWT, and WTC indicate that the solar weak magnetic activity on the full disk, which is represented by MPSI, dominates the inter-solar-cycle variation of TSI.« less

Structural studies on carbon materials for advanced space technology. Part 1: Structure and oxidation behavior of some carbon/carbon composite materials

NASA Technical Reports Server (NTRS)

Fischbach, D. B.; Uptegrove, D. R.; Srinivasagopalan, S.

1974-01-01

The microstructure and some microstructural effects of oxidation have been investigated for laminar carbon fiber cloth/cloth binder matrix composite materials. It was found that cloth wave is important in determining the macrostructure of the composites X-ray diffraction analysis showed that the composites were more graphitic than the constituent fiber phases, indicating a graphitic binder matrix phase. Various tests which were conducted to investigate specific properties of the material are described. It was learned that under the moderate temperature and oxidant flow conditions studied, C-700, 730 materials exhibit superior oxidation resistance primarily because of the inhibiting influence of the graphitized binder matrix.

Predicting major element mineral/melt equilibria - A statistical approach

NASA Technical Reports Server (NTRS)

Hostetler, C. J.; Drake, M. J.

1980-01-01

Empirical equations have been developed for calculating the mole fractions of NaO0.5, MgO, AlO1.5, SiO2, KO0.5, CaO, TiO2, and FeO in a solid phase of initially unknown identity given only the composition of the coexisting silicate melt. The approach involves a linear multivariate regression analysis in which solid composition is expressed as a Taylor series expansion of the liquid compositions. An internally consistent precision of approximately 0.94 is obtained, that is, the nature of the liquidus phase in the input data set can be correctly predicted for approximately 94% of the entries. The composition of the liquidus phase may be calculated to better than 5 mol % absolute. An important feature of this 'generalized solid' model is its reversibility; that is, the dependent and independent variables in the linear multivariate regression may be inverted to permit prediction of the composition of a silicate liquid produced by equilibrium partial melting of a polymineralic source assemblage.

The composition of secondary amorphous phases under different environmental conditions

NASA Astrophysics Data System (ADS)

Smith, R.; Rampe, E. B.; Horgan, B. H. N.; Dehouck, E.; Morris, R. V.

2017-12-01

X-ray diffraction (XRD) patterns measured by the CheMin instrument on the Mars Science Laboratory Curiosity rover demonstrate that amorphous phases are major components ( 15-60 wt%) of all rock and soil samples in Gale Crater. The nature of these phases is not well understood and could be any combination of primary (e.g., glass) and secondary (e.g., silica, ferrihydrite) phases. Secondary amorphous phases are frequently found as weathering products in soils on Earth, but these materials remain poorly characterized. Here we study a diverse suite of terrestrial samples including: sediments from recently de-glaciated volcanoes (Oregon), modern volcanic soils (Hawaii), and volcanic paleosols (Oregon) in order to determine how formation environment, climate, and diagenesis affect the abundance and composition of amorphous phases. We combine bulk XRD mineralogy with bulk chemical compositions (XRF) to calculate the abundance and bulk composition of the amorphous materials in our samples. We then utilize scanning transmission electron microscopy (STEM) and energy dispersive x-ray spectroscopy (EDS) to study the composition of individual amorphous phases at the micrometer scale. XRD analyses of 8 samples thus far indicate that the abundance of amorphous phases are: modern soils (20-80 %) > paleosols (15-40 %) > glacial samples (15-30 %). Initial calculations suggest that the amorphous components consist primarily of SiO2, Al2O3, TiO2, FeO and Fe2O3, with minor amounts of other oxides (e.g., MgO, CaO, Na2O). Compared to their respective crystalline counterparts, calculations indicate bulk amorphous components enriched in SiO2 for the glacial sample, and depleted in SiO2 for the modern soil and paleosol samples. STEM analyses reveal that the amorphous components consist of a number of different phases. Of the two samples analyzed using STEM thus far, the secondary amorphous phases have compositions with varying ratios of SiO2, Al2O3, TiO2, and Fe-oxides, consistent with mass balance calculation results, but inconsistent with well-known amorphous phase compositions (e.g., allophane, ferrihydrite). These results show that a number of secondary amorphous phases can form within a single soil environment. Continued analysis can help determine whether compositional trends can be linked to environmental factors.

Ultrasonic Nondestructive Evaluation Techniques Applied to the Quantitative Characterization of Textile Composite Materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1997-01-01

In this Progress Report, we describe our recent developments of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns for a thin woven composite in an immersion setup. In addition, we compare apparent signal loss measurements of the thin woven composite for phase-sensitive and phase-insensitive detection methods. All images of diffraction patterns have been included on the accompanying CD-ROM in the Adobe(Trademark) Portable Document Format (PDF). Due to the extensive amount of data, however, hardcopies of only a small representative selection of the images are included within the printed report. This Progress Report presents experimental results that support successful implementation of single element as well as one and two-dimensional ultrasonic array technologies for the inspection of textile composite structures. In our previous reports, we have addressed issues regarding beam profiles of ultrasonic pressure fields transmitted through a water reference path and transmitted through a thin woven composite sample path. Furthermore, we presented experimental results of the effect of a thin woven composite on the magnitude of an insonifying ultrasonic pressure field. In addition to the study of ultrasonic beam profiles, we consider issues relevant to the application of single-element, one-dimensional, and two-dimensional array technologies towards probing the mechanical properties of advanced engineering composites and structures. We provide comparisons between phase-sensitive and phase-insensitive detection methods for determination of textile composite structure parameters. We also compare phase-sensitive and phase-insensitive - - ---- ----- apparent signal loss measurements in an effort to study the phenomenon of phase cancellation at the face of a finite-aperture single-element receiver. Furthermore, in this Progress Report we extend our work on ultrasonic beam profile issues through investigation of the phase fronts of the pressure field. In Section H of this Progress Report we briefly describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. Section III details the analysis of the experimental data followed by the experimental results in Section IV. Finally, a discussion of the observations and conclusions is found in Section V.

Formation, Phase, and Elemental Composition of Micro- and Nano-Dimensional Particles of the Fe-Ti System

NASA Astrophysics Data System (ADS)

Dresvyannikov, A. F.; Kolpakov, M. E.

2018-05-01

X-ray fluorescence, X-ray phase analysis, and transmission Mössbauer and NGR spectrometry are used to study the formation, phase, and elemental composition of Fe-Ti particles. The interaction between Fe(III) ions and dispersed titanium in an aqueous solution containing chloride ions and HF is studied. It is shown that the resulting Fe-Ti samples are a set of core-shell microparticles with titanium cores coated with micro- and nanosized α-Fe nucleation centers with the thinness outer layer of iron(III) oxide characterized by a developed surface.

The phase behavior of cationic lipid-DNA complexes.

PubMed Central

May, S; Harries, D; Ben-Shaul, A

2000-01-01

We present a theoretical analysis of the phase behavior of solutions containing DNA, cationic lipids, and nonionic (helper) lipids. Our model allows for five possible structures, treated as incompressible macroscopic phases: two lipid-DNA composite (lipoplex) phases, namely, the lamellar (L(alpha)(C)) and hexagonal (H(II)(C)) complexes; two binary (cationic/neutral) lipid phases, that is, the bilayer (L(alpha)) and inverse-hexagonal (H(II)) structures, and uncomplexed DNA. The free energy of the four lipid-containing phases is expressed as a sum of composition-dependent electrostatic, elastic, and mixing terms. The electrostatic free energies of all phases are calculated based on Poisson-Boltzmann theory. The phase diagram of the system is evaluated by minimizing the total free energy of the three-component mixture with respect to all the compositional degrees of freedom. We show that the phase behavior, in particular the preferred lipid-DNA complex geometry, is governed by a subtle interplay between the electrostatic, elastic, and mixing terms, which depend, in turn, on the lipid composition and lipid/DNA ratio. Detailed calculations are presented for three prototypical systems, exhibiting markedly different phase behaviors. The simplest mixture corresponds to a rigid planar membrane as the lipid source, in which case, only lamellar complexes appear in solution. When the membranes are "soft" (i.e., low bending modulus) the system exhibits the formation of both lamellar and hexagonal complexes, sometimes coexisting with each other, and with pure lipid or DNA phases. The last system corresponds to a lipid mixture involving helper lipids with strong propensity toward the inverse-hexagonal phase. Here, again, the phase diagram is rather complex, revealing a multitude of phase transitions and coexistences. Lamellar and hexagonal complexes appear, sometimes together, in different regions of the phase diagram. PMID:10733951

THE PHYSICAL AND CHEMICAL MICROSTRUCTURE OF THE ACHATINA FULICA EPIPHRAGM.

PubMed

Struthers, M.; Rosair, G.; Buckman, J.; Viney, C.

2002-05-01

Microstructural characterization of Achatina fulica Bowdich, 1822 epiphragms and mucus secretions was performed to address two questions: what are the structure and composition of the reinforcing inorganic phase in the epiphragms, and what enables a durable epiphragm to form quickly in comparison to other biomineralized materials? Characterization was performed by a combination of light microscopy (relying on a variety of contrast modes), wet chemical tests, environmental scanning electron microscopy (including the use of energy dispersive X-ray analysis to obtain compositional data), and X-ray diffraction. The morphology of the inorganic phase promotes mechanical interlocking and presents a large surface for binding to the organic matrix. Strong binding occurs between the organic and inorganic phases. The inorganic phase adopts the calcite structure; its composition is Ca(0.912) Mg(0.088) CO(3). Epiphragms can form quickly because pre-grown crystals of the inorganic reinforcing phase are co-deposited with the mucus matrix. Unlike other biomineralized material, the crystals are not solution-grown in situ on an organic template in the final product.

Refining the phase diagram of Pb{sub 1−x}La{sub x}(Zr{sub 0.9}Ti{sub 0.1}){sub 1−x/4}O{sub 3} ceramics by structural, dielectric, and anelastic spectroscopy investigations

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

Craciun, F., E-mail: Floriana.Craciun@isc.cnr.it; Cordero, F.; Ciuchi, I. V.

2015-05-14

We present the results of dielectric and anelastic spectroscopy measurements, together with X-ray diffraction investigations, which allow us to establish more precisely the phase diagram of Pb{sub 1−x}La{sub x}(Zr{sub 0.9}Ti{sub 0.1}){sub 1−x/4}O{sub 3} (PLZT x/90/10) in the compositional range around the AFE/FE phase boundary (0 < x < 0.04). From structural analysis and polarization-electric field measurements, we have found that the ground state of PLZT samples with x < 0.025 is rhombohedral R3c, while samples with x > 0.032 are antiferroelectric with orthorhombic Pbam structure. In-between, for compositions with 0.025 ≤ x ≤ 0.032, a coexistence of the AFE/FE phases is evidenced. The use of complementary dielectric and anelastic techniques allows tomore » follow the phase transitions shifts throughout all the interesting composition range and to construct the temperature-composition phase diagram. The tilt instability line, separating the R3c and R3m low and high temperature phases, has been evidenced. Moreover, the new transition, associated with the onset of disordered tilting preceding the long range order of the R3c phase, previously found in Zr-rich Pb(Zr,Ti)O{sub 3}, is confirmed in rhombohedral PLZT x/90/10 compositions.« less

Effect of composition ratio on the thermal and physical properties of semicrystalline PLA/PHB-HHx composites.

PubMed

Lim, Jung Seop; Park, Ku-il; Chung, Gun Soo; Kim, Jong Hoon

2013-05-01

In this study, composites of semicrystalline, biodegradable polylactide (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-HHx) were prepared by direct melt compounding. The physical and thermal properties of the composites were investigated as a function of the composition ratio. Differential scanning calorimetry analysis indicated that PLA and PHB-HHx formed immiscible composites over the observed range of composition. The crystallization of PLA was gradually suppressed by increasing proportions of PHB-HHx. Dynamic mechanical analysis results confirmed that the innate ductility of PHB-HHX and its inhibiting effect on PLA crystallization improved the stiffness of the composite compared to those of neat PLA. The infrared spectra of the immiscible PLA/PHB-HHx composites at two crystallization temperatures (30 °C, 130 °C) were obtained and presented. At 30 °C, PHB-HHx existed as crystalline domains in the PLA matrix, while, amorphous phase of molten PHB-HHx was diffused within the crystalline phase of PLA at 130 °C. The interaction between PHB-HHX and PLA could not be elucidated from the temperature data. Mechanical tests showed that the addition of PHB-HHx improves ductility of PLA/PHB-HHx composite. Morphological analysis revealed that small proportions of PHB-HHx exhibited less tendency to aggregate, which resulted in greater plastic deformation and improved toughness. From this study, PLA blended with small portions of PHB-HHx may further expand the use of bio-friendly resources in a variety of applications such as flexible films, food packaging and something like that. Copyright © 2013 Elsevier B.V. All rights reserved.

Gas- and particle-phase chemical composition measurements onboard the G-1 research aircraft during the GoAmazon campaign.

NASA Astrophysics Data System (ADS)

Shilling, J.; Pekour, M. S.; Fortner, E.; Hubbe, J. M.; Longo, K.; Martin, S. T.; Mei, F.; Springston, S. R.; Tomlinson, J. M.; Wang, J.

2014-12-01

The Green Ocean Amazon (GoAmazon) campaign conducted from January 2014 - December 2015 in the vicinity of Manaus, Brazil, was designed to study the aerosol lifecycle and aerosol-cloud interactions in both pristine and anthropogenically influenced conditions. As part of this campaign, the DOE G-1 research aircraft was deployed from February 17th - March 25th 2014 and September 6th - October 5th 2014 to investigate aerosol and cloud properties aloft. An Aerodyne High Resolution Aerosol Mass Spectrometer (AMS) and an Ionicon Proton Transfer Reaction Mass Spectrometer (PTRMS) were part of the G-1 research aircraft payload and were used to investigate aerosol gas- and particle-phase chemical composition. Here we present preliminary analysis of the aerosol and gas phase chemical composition. PTR-MS measurements show that isoprene and its oxidation products are the dominant VOCs during research flights. HR-AMS measurements reveal that the particle phase is dominated by organic material with smaller concentrations of sulfate and nitrate observed. Organic particle concentrations are enhanced when encountering the urban plume from Manaus. During the wet season, we observe increased concentrations of organic particle when passing through low-altitude clouds. PMF analysis of the organic mass spectra shows that the chemical composition of the particles observed in-cloud is distinctly different from particles observed outside clouds. We will also compare measurements made during the wet and dry seasons.

Effect of Liquid-Crystalline Epoxy Backbone Structure on Thermal Conductivity of Epoxy-Alumina Composites

NASA Astrophysics Data System (ADS)

Giang, Thanhkieu; Kim, Jinhwan

2017-01-01

In a series of papers published recently, we clearly demonstrated that the most important factor governing the thermal conductivity of epoxy-Al2O3 composites is the backbone structure of the epoxy. In this study, three more epoxies based on diglycidyl ester-terminated liquid-crystalline epoxy (LCE) have been synthesized to draw conclusions regarding the effect of the epoxy backbone structure on the thermal conductivity of epoxy-alumina composites. The synthesized structures were characterized by proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FT-IR) spectroscopy. Differential scanning calorimetry, thermogravimetric analysis, and optical microscopy were also employed to examine the thermal and optical properties of the synthesized LCEs and the cured composites. All three LCE resins exhibited typical liquid-crystalline behaviors: clear solid crystalline state below the melting temperature ( T m), sharp crystalline melting at T m, and transition to nematic phase above T m with consequent isotropic phase above the isotropic temperature ( T i). The LCE resins displayed distinct nematic liquid-crystalline phase over a wide temperature range and retained liquid-crystalline phase after curing, with high thermal conductivity of the resulting composite. The thermal conductivity values ranged from 3.09 W/m-K to 3.89 W/m-K for LCE-Al2O3 composites with 50 vol.% filler loading. The steric effect played a governing role in the difference. The neat epoxy resin thermal conductivity was obtained as 0.35 W/m-K to 0.49 W/m-K based on analysis using the Agari-Uno model. The results clearly support the objective of this study in that the thermal conductivity of the LCE-containing networks strongly depended on the epoxy backbone structure and the degree of ordering in the cured network.

CSpace: an integrated workplace for the graphical and algebraic analysis of phase assemblages on 32-bit wintel platforms

NASA Astrophysics Data System (ADS)

Torres-Roldan, Rafael L.; Garcia-Casco, Antonio; Garcia-Sanchez, Pedro A.

2000-08-01

CSpace is a program for the graphical and algebraic analysis of composition relations within chemical systems. The program is particularly suited to the needs of petrologists, but could also prove useful for mineralogists, geochemists and other environmental scientists. A few examples of what can be accomplished with CSpace are the mapping of compositions into some desired set of system/phase components, the estimation of reaction/mixing coefficients and assessment of phase-rule compatibility relations within or between complex mineral assemblages. The program also allows dynamic inspection of compositional relations by means of barycentric plots. CSpace provides an integrated workplace for data management, manipulation and plotting. Data management is done through a built-in spreadsheet-like editor, which also acts as a data repository for the graphical and algebraic procedures. Algebraic capabilities are provided by a mapping engine and a matrix analysis tool, both of which are based on singular-value decomposition. The mapping engine uses a general approach to linear mapping, capable of handling determined, underdetermined and overdetermined problems. The matrix analysis tool is implemented as a task "wizard" that guides the user through a number of steps to perform matrix approximation (finding nearest rank-deficient models of an input composition matrix), and inspection of null-reaction space relationships (i.e. of implicit linear relations among the elements of the composition matrix). Graphical capabilities are provided by a graph engine that directly links with the contents of the data editor. The graph engine can generate sophisticated 2-D ternary (triangular) and 3D quaternary (tetrahedral) barycentric plots and includes features such as interactive re-sizing and rotation, on-the-fly coordinate scaling and support for automated drawing of tie lines.

Development of Ni-Ferrite-Based PVDF Nanomultiferroics

NASA Astrophysics Data System (ADS)

Behera, C.; Choudhary, R. N. P.; Das, Piyush R.

2017-10-01

Thin-film polyvinylidene fluoride (PVDF)-spinel ferrite nanocomposites with 0-3 connectivity and varying composition, i.e., (1 - x)PVDF- xNiFe2O4 ( x = 0.05, 0.1, 0.15), have been fabricated by a solution-casting route. The basic crystal data and microstructure of the composite samples were obtained by x-ray powder diffraction analysis and scanning electron microscopy, respectively. Preliminary structural analysis showed the presence of polymeric electroactive β-phase of PVDF (matrix) and spinel ferrite (filler) phase in the composites. The composites were found to be flexible with high relative dielectric constant ( ɛ r) and low loss tangent (tan δ). Detailed studies of their electrical characteristics using complex impedance spectroscopy showed the contributions of bulk (grains) and grain boundaries in the resistive and capacitive properties of the composites. Study of the frequency-dependent electrical conductivity at different temperatures showed that Jonscher's power law could be used to interpret the transport properties of the composites. Important experimental data and results obtained from magnetic as well ferroelectric hysteresis loops and the first-order magnetoelectric coefficient suggest the suitability of some of these composites for fabrication of multifunctional devices. The low electrical conductivity, high dielectric constant, and low loss tangent suggest that such composites could be used in capacitor devices.

Processing and properties of SiC whisker reinforced Si sub 3 N sub 4 ceramic matrix composites

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

Nunn, S.D.

1991-01-01

Silicon carbide whiskers reinforced silicon nitride ceramic matrix composites were pressureless sintered to high density by liquid phase sintering. Important processing parameters included: whisker dispersion by ultrasonic shear homogenization, particle refinement by attrition milling, pressure slip casting to obtain high greed densities, and sintering in a protective powder bed to limit decomposition. Composites with a {beta}20-Si{sub 3}N{sub 4} solid solution matrix containing 20 vol.% SiC whiskers were sintered to 98-100% theoretical density; composites having a Si{sub 3}N{sub 4} matrix containing YAG sintering aid were sintered to 98% of the theoretical density with 20 vol.% SiC whiskers, and 94% density withmore » 30 vol.% SiC whiskers. Analysis of the pressureless sintered composites revealed orientation of the SiC whiskers and the Si{sub 3}N{sub 4} matrix grains. The mechanical properties of hot pressed Si{sub 3}N{sub 4} composites reinforced with 20 vol.% SiC whiskers were shown to depend on the characteristics of the intergranular phase. Variations in the properties of the composites were analyzed in terms of the amount and morphology of the secondary phase, and the development of internal residual stresses due to the thermal expansion mismatch between the sintering aid phase at the grain boundaries.« less

Non-destructive Quantitative Phase Analysis and Microstructural Characterization of Zirconium Coated U-10Mo Fuel Foils via Neutron Diffraction

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

Cummins, Dustin Ray; Vogel, Sven C.; Hollis, Kendall Jon

2016-10-18

This report uses neutron diffraction to investigate the crystal phase composition of uranium-molybdenum alloy foils (U-10Mo) for the CONVERT MP-1 Reactor Conversion Project, and determines the effect on alpha-uranium contamination following the deposition of a Zr metal diffusion layer by various methods: plasma spray deposition of Zr powders at LANL and hot co-rolling with Zr foils at BWXT. In summary, there is minimal decomposition of the gamma phase U-10Mo foil to alpha phase contamination following both plasma spraying and hot co-rolling. The average unit cell volume, i.e. lattice spacing, of the Zr layer can be mathematically extracted from the diffractionmore » data; co-rolled Zr matches well with literature values of bulk Zr, while plasma sprayed Zr shows a slight increase in the lattice spacing, indicative of interstitial oxygen in the lattice. Neutron diffraction is a beneficial alternative to conventional methods of phase composition, i.e. x ray diffraction (XRD) and destructive metallography. XRD has minimal penetration depth in high atomic number materials, particularly uranium, and can only probe the first few microns of the fuel plate; neutrons pass completely through the foil, allowing for bulk analysis of the foil composition and no issues with addition of cladding layers, as in the final, aluminum-clad reactor fuel plates. Destructive metallography requires skilled technicians, cutting of the foil into small sections, hazardous etching conditions, long polishing and microscopy times, etc.; the neutron diffraction system has an automated sample loader and can fit larger foils, so there is minimal analysis preparation; the total spectrum acquisition time is ~ 1 hour per sample. The neutron diffraction results are limited by spectra refinement/calculation times and the availability of the neutron beam source. In the case of LANSCE at Los Alamos, the beam operates ~50% of the year. Following the lessons learned from these preliminary results, optimizations to the process and analysis can be made, and neutron diffraction can become a viable and efficient technique for gamma/alpha phase composition determination for nuclear fuels.« less

Magnesium-Aluminum-Zirconium Oxide Amorphous Ternary Composite: A Dense and Stable Optical Coating

NASA Technical Reports Server (NTRS)

Sahoo, N. K.; Shapiro, A. P.

1998-01-01

In the present work, the process parameter dependent optical and structural properties of MgO-Al(2)O(3)-ZrO(2) ternary mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. The surface morphology, grain size distributions, crystallographic phases and process dependent material composition of films have been investigated through the use of Atomic Force Microscopy (AFM), X-ray diffraction analysis and Energy Dispersive X- ray (EDX) analysis. EDX analysis made evident the correlation between the optical constants and the process dependent compositions in the films. It is possible to achieve environmentally stable amorphous films with high packing density under certain optimized process conditions.

MgO-Al2O3-ZrO2 Amorphous Ternary Composite: A Dense and Stable Optical Coating

NASA Technical Reports Server (NTRS)

Shaoo, Naba K.; Shapiro, Alan P.

1998-01-01

The process-parameter-dependent optical and structural properties of MgO-Al2O3-ZrO2 ternary mixed-composite material were investigated. Optical properties were derived from spectrophotometric measurements. The surface morphology, grain size distributions, crystallographic phases, and process- dependent material composition of films were investigated through the use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray analysis. Energy-dispersive x-ray analysis made evident the correlation between the optical constants and the process-dependent compositions in the films. It is possible to achieve environmentally stable amorphous films with high packing density under certain optimized process conditions.

Fatigue Damage Evaluation of Short Carbon Fiber Reinforced Plastics Based on Phase Information of Thermoelastic Temperature Change.

PubMed

Shiozawa, Daiki; Sakagami, Takahide; Nakamura, Yu; Nonaka, Shinichi; Hamada, Kenichi

2017-12-06

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to evaluate fatigue damage in short carbon fiber composites. The distribution of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damage was detected from the distribution of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was more clearly detected than before by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the property that carbon fiber shows opposite phase thermoelastic temperature change.

A deformation-formulated micromechanics model of the effective Young's modulus and strength of laminated composites containing local ply curvature

NASA Technical Reports Server (NTRS)

Lee, Jong-Won; Harris, Charles E.

1990-01-01

A mathematical model based on the Euler-Bermoulli beam theory is proposed for predicting the effective Young's moduli of piecewise isotropic composite laminates with local ply curvatures in the main load-carrying layers. Strains in corrugated layers, in-phase layers, and out-of-phase layers are predicted for various geometries and material configurations by assuming matrix layers as elastic foundations of different spring constants. The effective Young's moduli measured from corrugated aluminum specimens and aluminum/epoxy specimens with in-phase and out-of-phase wavy patterns coincide very well with the model predictions. Moire fringe analysis of an in-phase specimen and an out-of-phase specimen are also presented, confirming the main assumption of the model related to the elastic constraint due to the matrix layers. The present model is also compared with the experimental results and other models, including the microbuckling models, published in the literature. The results of the present study show that even a very small-scale local ply curvature produces a noticeable effect on the mechanical constitutive behavior of a laminated composite.

Carbon and Sulfur Isotopic Composition of Rocknest Soil as Determined with the Sample Analysis at Mars(SAM) Quadrupole Mass Spectrometer

NASA Technical Reports Server (NTRS)

Franz, H. B.; McAdam, C.; Stern, J. C.; Archer, P. D., Jr.; Sutter, B.; Grotzinger, J. P.; Jones, J. H.; Leshin, L. A.; Mahaffy, P. R.; Ming, D. W.;

Design of new face-centered cubic high entropy alloys by thermodynamic calculation

NASA Astrophysics Data System (ADS)

Choi, Won-Mi; Jung, Seungmun; Jo, Yong Hee; Lee, Sunghak; Lee, Byeong-Joo

2017-09-01

A new face-centered cubic (fcc) high entropy alloy system with non-equiatomic compositions has been designed by utilizing a CALculation of PHAse Diagram (CALPHAD) - type thermodynamic calculation technique. The new alloy system is based on the representative fcc high entropy alloy, the Cantor alloy which is an equiatomic Co- Cr-Fe-Mn-Ni five-component alloy, but fully or partly replace the cobalt by vanadium and is of non-equiatomic compositions. Alloy compositions expected to have an fcc single-phase structure between 700 °C and melting temperatures are proposed. All the proposed alloys are experimentally confirmed to have the fcc single-phase during materials processes (> 800 °C), through an X-ray diffraction analysis. It is shown that there are more chances to find fcc single-phase high entropy alloys if paying attention to non-equiatomic composition regions and that the CALPHAD thermodynamic calculation can be an efficient tool for it. An alloy design technique based on thermodynamic calculation is demonstrated and the applicability and limitation of the approach as a design tool for high entropy alloys is discussed.

Phase composition and microstructure of WC-Co alloys obtained by selective laser melting

NASA Astrophysics Data System (ADS)

Khmyrov, Roman S.; Shevchukov, Alexandr P.; Gusarov, Andrey V.; Tarasova, Tatyana V.

2018-03-01

Phase composition and microstructure of initial WC, BK8 (powder alloy 92 wt.% WC-8 wt.% Co), Co powders, ball-milled powders with four different compositions (1) 25 wt.% WC-75 wt.% Co, (2) 30 wt.% BK8-70 wt.% Co, (3) 50 wt.% WC-50 wt.% Co, (4) 94 wt.% WC-6 wt.% Co, and bulk alloys obtained by selective laser melting (SLM) from as-milled powders in as-melted state and after heat treatment were investigated by scanning electron microscopy and X-ray diffraction analysis. Initial and ball-milled powders consist of WC, hexagonal α-Co and face-centered cubic β-Co. The SLM leads to the formation of major new phases W3Co3C, W4Co2C and face-centered cubic β-Co-based solid solution. During the heat treatment, there occurs partial decomposition of the face-centered cubic β-Co-based solid solution with the formation of W2C and hexagonal α-Co solid solution. The microstructure of obtained bulk samples, in general, corresponds to the observed phase composition.

Theoretical study of the composition pulling effect in InGaN metalorganic vapor-phase epitaxy growth

NASA Astrophysics Data System (ADS)

Inatomi, Yuya; Kangawa, Yoshihiro; Ito, Tomonori; Suski, Tadeusz; Kumagai, Yoshinao; Kakimoto, Koichi; Koukitu, Akinori

2017-07-01

The composition pulling effect in metalorganic vapor-phase InGaN epitaxy was theoretically investigated by thermodynamic analysis. The excess energies of biaxial-strained In x Ga1- x N were numerically calculated using empirical interatomic potentials considering different situations: (i) coherent growth on GaN(0001), (ii) coherent growth on In0.2Ga0.8N(0001), and (iii) bulk growth. Using the excess energies, the excess chemical potentials of InN and GaN alloys were computed. Our results show that compressive strain suppresses In incorporation, whereas tensile strain promotes it. Moreover, assuming chemical equilibrium, the relationship between the solid composition and the growth conditions was predicted. The results successfully reproduced the typical composition pulling effect.

Advanced surface chemical analysis of continuously manufactured drug loaded composite pellets.

PubMed

Hossain, Akter; Nandi, Uttom; Fule, Ritesh; Nokhodchi, Ali; Maniruzzaman, Mohammed

2017-04-15

The aim of the present study was to develop and characterise polymeric composite pellets by means of continuous melt extrusion techniques. Powder blends of a steroid hormone (SH) as a model drug and either ethyl cellulose (EC N10 and EC P7 grades) or hydroxypropyl methylcellulose (HPMC AS grade) as polymeric carrier were extruded using a Pharma 11mm twin screw extruder in a continuous mode of operation to manufacture extruded composite pellets of 1mm length. Molecular modelling study using commercial Gaussian 09 software outlined a possible drug-polymer interaction in the molecular level to develop solid dispersions of the drug in the pellets. Solid-state analysis conducted via a differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray powder diffraction (XRPD) analyses revealed the amorphous state of the drug in the polymer matrices. Surface analysis using SEM/energy dispersive X-ray (EDX) of the produced pellets arguably showed a homogenous distribution of the C and O atoms in the pellet matrices. Moreover, advanced chemical surface analysis conducted via atomic force microscopy (AFM) showed a homogenous phase system having the drug molecule dispersed onto the amorphous matrices while Raman mapping confirmed the homogenous single-phase drug distribution in the manufactured composite pellets. Such composite pellets are expected to deliver multidisciplinary applications in drug delivery and medical sciences by e.g. modifying drug solubility/dissolutions or stabilizing the unstable drug (e.g. hormone, protein) in the composite network. Copyright © 2016. Published by Elsevier Inc.

Stability and Solid Solutions of Hydrous Alumino-Silicates in the Earth's Mantle

NASA Astrophysics Data System (ADS)

Panero, W. R.; Caracas, R.

2017-12-01

The degree to which the Earth's mantle stores and cycles water in excess of the storage capacity of nominally anhydrous minerals is dependent upon the stability of hydrous phases under mantle-relevant pressures, temperatures, and compositions. Two hydrous phases, phase D and phase H are stable to the pressures and temperatures of the Earth's lower mantle, suggesting that the Earth's lower mantle may participate in the cycling of water. Each phase has a wide solid solution series between MgSi2O6H2-Al2SiO6H2 and MgSiO4H2-2δAlOOH-SiO2, respectively, yet most work addresses end-member compositions for analysis of stability and elastic properties. We present the results of density functional theory calculations on the stability, structure, bonding, partitioning, and elasticity of hydrous phases D and H in the Al2O3-SiO2-MgO-H2O system, addressing the solid solution series through a statistical sampling of site occupancy and calculation of the partition function from the grand canonical ensemble. We find that the addition of Al to the endmember compositions stabilizes each phase to higher temperatures through additional configurational entropy. We further find that solid solutions tend not to undergo hydrogen-bond symmetrization as is found in the end member compositions as a result of non-symmetric bonding environments.

Development and Characterization of Sr-Containing Glass-Ceramic Composites Based on Biogenic Hydroxyapatite

NASA Astrophysics Data System (ADS)

Kuda, Oleksii; Pinchuk, Nataliia; Bykov, Oleksandr; Tomila, Tamara; Olifan, Olena; Golovkova, Maryna

2018-05-01

Composite materials based on hydroxyapatite are widely used for bone tissue engineering. There is evidence of a positive effect of the presence of strontium in osteoplastic materials in the case of a Ca/Sr certain ratio. To examine the effect of the addition of Sr2+, a study was made by introducing it into the material composition based on biogenic hydroxyapatite and sodium borosilicate glass (50/50% wt.). The strontium was introduced into the composition in an amount of 1% wt. Composite materials were obtained at final sintering temperatures of 780 °C and a sintering time of 1 h. The effect of additions of glass phase and strontium affect changes in the crystal lattice of biogenic hydroxyapatite was investigated with the help of X-ray phase analysis, IR spectroscopy. Also the behavior of composites in vitro in physiological solution was studied.

The effect of reaction conditions on formation of wet precipitated calcium phosphates

NASA Astrophysics Data System (ADS)

Huang, Chen; Cao, Peng

2015-03-01

The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for sample characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.

Orthodontic archwire composition and phase analyses by neutron spectroscopy.

PubMed

Tian, Kun V; Festa, Giulia; Basoli, Francesco; Laganà, Giuseppina; Scherillo, Antonella; Andreani, Carla; Bollero, Patrizio; Licoccia, Silvia; Senesi, Roberto; Cozza, Paola

2017-05-31

Quantitative metallurgical and phase analyses employing neutron diffraction technique were conducted on two as-received commercial rectangular austenitic stainless steel orthodontic archwires, G&H and Azdent, 0.43×0.64 mm (0.017×0.025 inch). Results showed a bi-phase structure containing martensitic phase (45.67% for G&H and 6.62% for Azdent) in addition to the expected metastable austenite. The former may be a strain-induced phase-transformation arising during the cold working process of wire fabrication. Further neutron resonance capture analysis determinations provided atomic and isotopic compositions, including alloying elements in each sample, complementary to the results of traditional energy dispersive X-ray spectroscopy. Together, these results assist in relating commercial alloying recipes and processing histories with mechanical performance, strength and ductility in particular.

Qualitative human body composition analysis assessed with bioelectrical impedance.

PubMed

Talluri, T

1998-12-01

Body composition is generally aiming at quantitative estimates of fat mass, inadequate to assess nutritional states that on the other hand are well defined by the intra/extra cellular masses proportion (ECM/BCM). Direct measures performed with phase sensitive bioelectrical impedance analyzers can be used to define the current distribution in normal and abnormal populations. Phase angle and reactance nomogram is directly reflecting the ECM/BCM pathways proportions and body impedance analysis (BIA) is also validated to estimate the individual content of body cell mass (BCM). A new body cell mass index (BCMI) obtained dividing the weight of BCM in kilograms by the body surface in square meters is confronted to the scatterplot distribution of phase angle and reactance values obtained from controls and patients, and proposed as a qualitative approach to identify abnormal ECM/BCM ratios and nutritional states.

Effective properties of dispersed phase reinforced composite materials with perfect and imperfect interfaces

NASA Astrophysics Data System (ADS)

Han, Ru

This thesis focuses on the analysis of dispersed phase reinforced composite materials with perfect as well as imperfect interfaces using the Boundary Element Method (BEM). Two problems of interest are considered, namely, to determine the limitations in the use of effective properties and the analysis of failure progression at the inclusion-matrix interface. The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of composite materials can be determined at the mesoscopic level using three-dimensional parallel BEM simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach can be determined. Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interface in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks along the interfaces. The effect of decohesion on the macroscopic response of composite materials is also investigated.

Methods of chemical and phase composition analysis of gallstones

NASA Astrophysics Data System (ADS)

Suvorova, E. I.; Pantushev, V. V.; Voloshin, A. E.

2017-11-01

This review presents the instrumental methods used for chemical and phase composition investigation of gallstones. A great body of data has been collected in the literature on the presence of elements and their concentrations, obtained by fluorescence microscopy, X-ray fluorescence spectroscopy, neutron activation analysis, proton (particle) induced X-ray emission, atomic absorption spectroscopy, high-resolution gamma-ray spectrometry, electron paramagnetic resonance. Structural methods—powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy—provide information about organic and inorganic phases in gallstones. Stone morphology was studied at the macrolevel with optical microscopy. Results obtained by analytical scanning and transmission electron microscopy with X-ray energy dispersive spectrometry are discussed. The chemical composition and structure of gallstones determine the strategy of removing stone from the body and treatment of patients: surgery or dissolution in the body. Therefore one chapter of the review describes the potential of dissolution methods. Early diagnosis and appropriate treatment of the disease depend on the development of clinical methods for in vivo investigation, which gave grounds to present the main characteristics and potential of ultrasonography (ultrasound scanning), magnetic resonance imaging, and X-ray computed tomography.

Spectroscopic characterization of bone tissue of experimental animals after glucocorticoid treatment and recovery period

NASA Astrophysics Data System (ADS)

Mitić, Žarko J.; Najman, Stevo J.; Cakić, Milorad D.; Ajduković, Zorica R.; Ignjatović, Nenad L.; Nikolić, Ružica S.; Nikolić, Goran M.; Stojanović, Sanja T.; Vukelić, Marija Đ.; Trajanović, Miroslav D.

2014-09-01

The influence of glucocorticoids on the composition and mineral/organic content of the mandible in tested animals after recovery and healing phase was investigated in this work. The results of FTIR analysis demonstrated that bone tissue composition was changed after glucocorticoid treatment. The increase of calcium, magnesium, phosphorus content and mineral part of bones was statistically significant in recovery phase and in treatment phase that included calcitonin and thymus extract. Some changes also happened in the organic part of the matrix, as indicated by intensity changes for already present IR bands and the appearance of new IR bands in the region 3500-1300 cm-1.

Supercooling effects in faceted eutectic Nb-Si alloys

NASA Technical Reports Server (NTRS)

Gokhale, A. B.; Sarkar, G.; Abbaschian, G. J.; Haygarth, J. C.; Wojcik, C.

1988-01-01

The effect of melt supercooling on the microstructure of an Nb-58 at. pct Si alloy is investigated experimentally using an electromagnetic levitation apparatus. It is found that, starting with an alloy nominally of eutectic composition, nucleation of Nb5Si3 occurs in the supercooled liquid first. Upon further cooling, the remaining liquid continues to supercool until the second phase, NbSi2 is nucleated, which is commonly accompanied by rapid recalescence. The primary phase exibits a eutectoid-type decomposition. The observations are discussed with reference to the results of quantitative microstructural measurements, compositional and thermal analysis, and preliminary thermodynamic modeling of the phase diagram.

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

Tumurugoti, P.; Clark, B.M.; Edwards, D.J.

Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by x-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirmed hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of selected elements observed by wavelength dispersive spectroscopy (WDS) maps indicated that Cs formed a secondary phase during SPS processing, which was considered undesirable. On the other hand, Cs partitioned into the hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition by selected area electron diffractionmore » (SAED) revealed ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice.« less

An equivalent dipole analysis of PZT ceramics and lead-free piezoelectric single crystals

NASA Astrophysics Data System (ADS)

Bell, Andrew J.

2016-04-01

The recently proposed Equivalent Dipole Model for describing the electromechanical properties of ionic solids in terms of 3 ions and 2 bonds has been applied to PZT ceramics and lead-free single crystal piezoelectric materials, providing analysis in terms of an effective ionic charge and the asymmetry of the interatomic force constants. For PZT it is shown that, as a function of composition across the morphotropic phase boundary, the dominant bond compliance peaks at 52% ZrO2. The stiffer of the two bonds shows little composition dependence with no anomaly at the phase boundary. The effective charge has a maximum value at 50% ZrO2, decreasing across the phase boundary region, but becoming constant in the rhombohedral phase. The single crystals confirm that both the asymmetry in the force constants and the magnitude of effective charge are equally important in determining the values of the piezoelectric charge coefficient and the electromechanical coupling coefficient. Both are apparently temperature dependent, increasing markedly on approaching the Curie temperature.

Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Min, J. B.; Xue, D.; Shi, Y.

2013-01-01

A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens.

Estimation of the magnetic entropy change by means of Landau theory and phenomenological model in La0.6Ca0.2 Sr0.2MnO3/Sb2O3 ceramic composites

NASA Astrophysics Data System (ADS)

Nasri, M.; Dhahri, E.; Hlil, E. K.

2018-06-01

In this paper, magnetocaloric properties of La0.6Ca0.2Sr0.2MnO3/Sb2O3 oxides have been investigated. The composite samples were prepared using the conventional solid-state reaction method. The second-order phase transition can be testified with the positive slope in Arrott plots. An excellent agreement has been found between the -ΔSM values estimated by Landau theory and those obtained using the classical Maxwell relation. The field dependence of the magnetic entropy change analysis shows a power law dependence,|ΔSM|≈Hn , with n(TC) = 0.65. Moreover, the scaling analysis of magnetic entropy change exhibits that ΔSM(T) curves collapse into a single universal curve, indicating that the observed paramagnetic to ferromagnetic phase transition is an authentic second-order phase transition. The maximum value of magnetic entropy change of composites is found to decrease slightly with the further increasing of Sb2O3 concentration. A phenomenological model was used to predict magnetocaloric properties of La0.6Ca0.2Sr0.2MnO3/Sb2O3 composites. The theoretical calculations are compared with the available experimental data.

Fly ash reinforced thermoplastic vulcanizates obtained from waste tire powder.

PubMed

Sridhar, V; Xiu, Zhang Zhen; Xu, Deng; Lee, Sung Hyo; Kim, Jin Kuk; Kang, Dong Jin; Bang, Dae-Suk

2009-03-01

Novel thermoplastic composites made from two major industrial and consumer wastes, fly ash and waste tire powder, have been developed. The effect of increasing fly ash loadings on performance characteristics such as tensile strength, thermal, dynamic mechanical and magnetic properties has been investigated. The morphology of the blends shows that fly ash particles have more affinity and adhesion towards the rubbery phase when compared to the plastic phase. The fracture surface of the composites shows extensive debonding of fly ash particles. Thermal analysis of the composites shows a progressive increase in activation energy with increase in fly ash loadings. Additionally, morphological studies of the ash residue after 90% thermal degradation shows extensive changes occurring in both the polymer and filler phases. The processing ability of the thermoplastics has been carried out in a Monsanto processability testing machine as a function of shear rate and temperature. Shear thinning behavior, typical of particulate polymer systems, has been observed irrespective of the testing temperatures. Magnetic properties and percolation behavior of the composites have also been evaluated.

Analysis of the Microstructure and Mechanical Properties of Titanium-Based Composites Reinforced by Secondary Phases and B4C Particles Produced via Direct Hot Pressing

PubMed Central

Montealegre-Melendez, Isabel; Arévalo, Cristina; Ariza, Enrique; Rubio-Escudero, Cristina; Kitzmantel, Michael; Neubauer, Erich

2017-01-01

In the last decade, titanium metal matrix composites (TMCs) have received considerable attention thanks to their interesting properties as a consequence of the clear interface between the matrix and the reinforcing phases formed. In this work, TMCs with 30 vol % of B4C are consolidated by hot pressing. This technique is a powder metallurgy rapid process. Incorporation of the intermetallic to the matrix, 20 vol % (Ti-Al), is also evaluated. Here, the reinforcing phases formed by the reaction between the titanium matrix and the ceramic particles, as well as the intermetallic addition, promote substantial variations to the microstructure and to the properties of the fabricated composites. The influences of the starting materials and the consolidation temperature (900 °C and 1000 °C) are investigated. By X-ray diffraction, scanning and transmission electron microscopy analysis, the in-situ-formed phases in the matrix and the residual ceramic particles were studied. Furthermore, mechanical properties are studied through tensile and bending tests in addition to other properties, such as Young’s modulus, hardness, and densification of the composites. The results show the significant effect of temperature on the microstructure and on the mechanical properties from the same starting powder. Moreover, the Ti-Al addition causes variation in the interface between the reinforcement and the matrix, thereby affecting the behaviour of the TMCs produced at the same temperature. PMID:29077066

Influence of Finishing and Polishing Techniques and Abrasion on Transmittance and Roughness of Composite Resins.

PubMed

Carneiro, Pma; Ramos, T M; de Azevedo, C S; de Lima, E; de Souza, Shj; Turbino, M L; Cesar, P F; Matos, A B

The aim of this study was to evaluate the influence of finishing and polishing systems and toothbrush abrasion on transmittance (T) and surface roughness (Ra) of three composite resins (Filtek Z350 XT, Tetric N-Ceram, and IPS Empress Direct). Eighteen resin disks (10 mm diameter × 2 mm thick) finished by polyester strips had initial surface smoothness recorded, representing phase 1 (P1). Specimens were divided into three groups (n=6) according to the finishing/polishing instrument used (OneGloss, TopGloss, and Sof-Lex) to compose phase 2 samples (P2). Then specimens were subjected to 514 cycles of toothbrush simulation using a toothpaste slurry, with a constant load applied to soft bristles, and were then washed (phase 3=P3). After each phase, the specimens were examined by an optical profiler and spectrophotometer to measure Ra and T. Data were analyzed by analysis of variance, Tukey and Pearson tests. T values were statistically influenced by composite resin ( p=0.000) and phase of measurement ( p=0.000) factors, while the finishing/polishing system used ( p=0.741) did not affect T. On the other hand, Ra values were statistically affected by the factor finishing/polishing system ( p=0.000), but not by composite resin ( p=0.100) and phase of measurement ( p=0.451). Tetric N-Ceram and Empress Direct presented higher values of roughness when polished by OneGloss, while TopGloss and Sof-Lex showed a lower roughness. It can be concluded that composite resins transmitted more light after dental abrasion. Transmittance of composite resins was not modified by the distinct roughness created by finishing/polishing instruments.

Mass spectrometric determination of the composition of the Venus clouds

NASA Technical Reports Server (NTRS)

Herzog, R. F. K.

1973-01-01

The instrumentation is analyzed for determining the composition of the clouds on Venus. Direct analysis of the gas phase atmosphere, and the detection of ferrous chloride with a mass spectrometer are dicussed along with the mass analyzer, and the pre-separation of cloud particles from the ambient atmosphere.

Microstructural Influence on Deformation and Fatigue Life of Composites Using the Generalized Method of Cells

NASA Technical Reports Server (NTRS)

Arnold, S. M.; Murthy, P.; Bednarcyk, B. A.; Pineda, E. J.

2015-01-01

A fully coupled deformation and damage approach to modeling the response of composite materials and composite laminates is presented. It is based on the semi-­-analytical generalized method of cells (GMC) micromechanics model as well as its higher fidelity counterpart, HFGMC, both of which provide closed-form constitutive equations for composite materials as well as the micro scale stress and strain fields in the composite phases. The provided constitutive equations allow GMC and HFGMC to function within a higher scale structural analysis (e.g., finite element analysis or lamination theory) to represent a composite material point, while the availability of the micro fields allow the incorporation of lower scale sub­-models to represent local phenomena in the fiber and matrix. Further, GMC's formulation performs averaging when applying certain governing equations such that some degree of microscale field accuracy is surrendered in favor of extreme computational efficiency, rendering the method quite attractive as the centerpiece in a integrated computational material engineering (ICME) structural analysis; whereas HFGMC retains this microscale field accuracy, but at the price of significantly slower computational speed. Herein, the sensitivity of deformation and the fatigue life of graphite/epoxy PMC composites, with both ordered and disordered microstructures, has been investigated using this coupled deformation and damage micromechanics based approach. The local effects of fiber breakage and fatigue damage are included as sub-models that operate on the microscale for the individual composite phases. For analysis of laminates, classical lamination theory is employed as the global or structural scale model, while GMC/HFGMC is embedded to operate on the microscale to simulate the behavior of the composite material within each laminate layer. A key outcome of this study is the statistical influence of microstructure and micromechanics idealization (GMC or HFGMC) on the overall accuracy of unidirectional and laminated composite deformation and fatigue response.

Raman scattering in HfxZr1-xO2 nanoparticles

NASA Astrophysics Data System (ADS)

Robinson, Richard D.; Tang, Jing; Steigerwald, Michael L.; Brus, Louis E.; Herman, Irving P.

2005-03-01

Raman spectroscopy demonstrates that ˜5nm dimension HfxZr1-xO2 nanocrystals prepared by a nonhydrolytic sol-gel synthesis method are solid solutions of hafnia and zirconia, with no discernable segregation within the individual nanoparticles. Zirconia-rich particles are tetragonal and ensembles of hafnia-rich particles show mixed tetragonal/monoclinic phases. Sintering at 1200 °C produces larger particles (20-30 nm) that are monoclinic. A simple lattice dynamics model with composition-averaged cation mass and scaled force constants is used to understand how the Raman mode frequencies vary with composition in the tetragonal HfxZr1-xO2 nanoparticles. Background luminescence from these particles is minimized after oxygen treatment, suggesting possible oxygen defects in the as-prepared particles. Raman scattering is also used to estimate composition and the relative fractions of tetragonal and monoclinic phases. In some regimes there are mixed phases, and Raman analysis suggests that in these regimes the tetragonal phase particles are relatively rich in zirconium and the monoclinic phase particles are relatively rich in hafnium.

Ferri-magnetic order in Mn induced spinel Co3-xMnxO4 (0.1≤x≤1.0) ceramic compositions

NASA Astrophysics Data System (ADS)

Meena, P. L.; Sreenivas, K.; Singh, M. R.; Kumar, Ashok; Singh, S. P.; Kumar, Ravi

2016-04-01

We report structural and magnetic properties of spinel Co3-xMnxO4 (x=0.1-1.0) synthesized by solid state reaction technique. Rietveld refinement analysis of X-ray diffraction (XRD) data, revealed the formation of polycrystalline single phase Co3-xMnxO4 without any significant structural change in cubic crystal symmetry with Mn substitution, except change in lattice parameter. Temperature dependent magnetization data show changes in magnetic ordering temperature, indicating formation of antiferromagnetic (AFM) and ferrimagnetic (FM) phase at low Mn concentration (x≤0.3) and well-defined FM phase at high Mn concentration (x≥0.5). The isothermal magnetization records established an AFM/FM mixed phase for composition ranging 0.10.5.

Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

NASA Astrophysics Data System (ADS)

Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

2016-04-01

This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

Concurrent Probabilistic Simulation of High Temperature Composite Structural Response

NASA Technical Reports Server (NTRS)

Abdi, Frank

1996-01-01

A computational structural/material analysis and design tool which would meet industry's future demand for expedience and reduced cost is presented. This unique software 'GENOA' is dedicated to parallel and high speed analysis to perform probabilistic evaluation of high temperature composite response of aerospace systems. The development is based on detailed integration and modification of diverse fields of specialized analysis techniques and mathematical models to combine their latest innovative capabilities into a commercially viable software package. The technique is specifically designed to exploit the availability of processors to perform computationally intense probabilistic analysis assessing uncertainties in structural reliability analysis and composite micromechanics. The primary objectives which were achieved in performing the development were: (1) Utilization of the power of parallel processing and static/dynamic load balancing optimization to make the complex simulation of structure, material and processing of high temperature composite affordable; (2) Computational integration and synchronization of probabilistic mathematics, structural/material mechanics and parallel computing; (3) Implementation of an innovative multi-level domain decomposition technique to identify the inherent parallelism, and increasing convergence rates through high- and low-level processor assignment; (4) Creating the framework for Portable Paralleled architecture for the machine independent Multi Instruction Multi Data, (MIMD), Single Instruction Multi Data (SIMD), hybrid and distributed workstation type of computers; and (5) Market evaluation. The results of Phase-2 effort provides a good basis for continuation and warrants Phase-3 government, and industry partnership.

Magnetic enhancement of ferroelectric polarization in a self-grown ferroelectric-ferromagnetic composite

NASA Astrophysics Data System (ADS)

Kumar, Amit; Narayan, Bastola; Pachat, Rohit; Ranjan, Rajeev

2018-02-01

Ferroelectric-ferromagnetic multiferroic composites are of great interest both from the scientific and technological standpoints. The extent of coupling between polarization and magnetization in such two-phase systems depends on how efficiently the magnetostrictive and electrostrictive/piezoelectric strain gets transferred from one phase to the other. This challenge is most profound in the easy to make 0-3 ferroelectric-ferromagnetic particulate composites. Here we report a self-grown ferroelectric-ferromagnetic 0-3 particulate composite through controlled spontaneous precipitation of ferrimagnetic barium hexaferrite phase (BaF e12O19 ) amid ferroelectric grains in the multiferroic alloy system BiFe O3-BaTi O3 . We demonstrate that a composite specimen exhibiting merely ˜1% hexaferrite phase exhibits ˜34% increase in saturation polarization in a dc magnetic field of ˜10 kOe. Using modified Rayleigh analysis of the polarization field loop in the subcoercive field region we argue that the substantial enhancement in the ferroelectric switching is associated with the reduction in the barrier heights of the pinning centers of the ferroelectric-ferroelastic domain walls in the stress field generated by magnetostriction in the hexaferrite grains when the magnetic field is turned on. Our study proves that controlled precipitation of the magnetic phase is a good strategy for synthesis of 0-3 ferroelectric-ferromagnetic particulate multiferroic composite as it not only helps in ensuring a good electrical insulating character of the composite, enabling it to sustain high enough electric field for ferroelectric switching, but also the factors associated with the spontaneity of the precipitation process ensure efficient transfer of the magnetostrictive strain/stress to the surrounding ferroelectric matrix making domain wall motion easy.

Preparation of Si3N4 Form Diatomite via a Carbothermal Reduction-Nitridation Process

NASA Astrophysics Data System (ADS)

Ma, Bin; Huang, Zhaohui; Mei, Lefu; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Hu, Xiaozhi

2016-05-01

Si3N4 was produced using diatomite and sucrose as silicon and carbon sources, respectively. The effect of the C/SiO2 molar ratio, heating temperature and soaking time on the morphology and phase compositions of the final products was investigated by scanning electron microscopy, x-ray diffraction analysis and energy dispersive spectroscopy. The phase equilibrium relationships of the system at different heating temperatures were also investigated based on the thermodynamic analysis. The results indicate that the phase compositions depended on the C/SiO2 molar ratio, heating temperature and soaking time. Fabrication of Si3N4 from the precursor via carbothermal reduction nitridation was achieved at 1550°C for 1-8 h using a C/SiO2 molar ratio of 3.0. The as-prepared Si3N4 contained a low amount of Fe3Si (<1 wt.%).

Thermotropic phase transitions in Pb{sub 1−x}Sr{sub x}(Al{sub 1/3}Nb{sub 2/3}){sub 0.1}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.9}O{sub 3} ceramics: Temperature dependent dielectric permittivity and Raman scattering

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

Li, C. Q.; Peng, L.; Jiang, K.

2015-06-15

The phase transitions of Pb{sub 1−x}Sr{sub x}(Al{sub 1/3}Nb{sub 2/3}){sub 0.1}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.9}O{sub 3} (Sr-modified PAN-PZT) ceramics with Sr compositions of x = 2%, 5%, 10% and 15% have been investigated using X-ray diffraction (XRD), temperature dependent dielectric permittivity and Raman scattering. The XRD analysis show that the phase transition occurs between Sr composition of 5% and 10%. Based on the broad dielectric peaks at 100 Hz, the diffused phase transition from tetragonal (T) to cubic (C) structure shifts to lower temperature with increasing Sr composition. The dramatic changes of wavenumber and full width at half-maximum (FWHM) for E(TO{sub 4})′more » softing mode can be observed at morphotropic phase boundary (MPB). Moreover, the MPB characteristic shows a wider and lower trend of temperature region with increasing Sr composition. It could be ascribed to the diminishment of the energy barrier and increment of A-cation entropy. Therefore, the Sr-modified PAN-PZT ceramics unambiguously undergo two successive structural transitions (rhombohedral-tetragonal-cubic phase) with temperature from 80 to 750 K. Correspondingly, the phase diagram of Sr-modified PAN-PZT ceramics can be well depicted.« less

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

PubMed

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

2011-03-01

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

Temperature- and composition-dependent hydrogen diffusivity in palladium from statistically-averaged molecular dynamics

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

Zhou, Xiaowang; Heo, Tae Wook; Wood, Brandon C.

Solid-state hydrogen storage materials undergo complex phase transformations whose kinetics is often limited by hydrogen diffusion. Among metal hydrides, palladium hydride undergoes a diffusional phase transformation upon hydrogen uptake, during which the hydrogen diffusivity varies with hydrogen composition and temperature. Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Our studies confirm significant dependence of the diffusivity on composition and temperature that elucidate key trends in the available experimental measurements. Whereas at low hydrogen compositions, a single process dominates, atmore » high hydrogen compositions, diffusion is found to exhibit behavior consistent with multiple hopping barriers. Further analysis, supported by nudged elastic band computations, suggests that the multi-barrier diffusion can be interpreted as two distinct mechanisms corresponding to hydrogen-rich and hydrogen-poor local environments.« less

Temperature- and composition-dependent hydrogen diffusivity in palladium from statistically-averaged molecular dynamics

DOE PAGES

Zhou, Xiaowang; Heo, Tae Wook; Wood, Brandon C.; ...

2018-03-09

Solid-state hydrogen storage materials undergo complex phase transformations whose kinetics is often limited by hydrogen diffusion. Among metal hydrides, palladium hydride undergoes a diffusional phase transformation upon hydrogen uptake, during which the hydrogen diffusivity varies with hydrogen composition and temperature. Here we perform robust statistically-averaged molecular dynamics simulations to obtain a well-converged analytical expression for hydrogen diffusivity in bulk palladium that is valid throughout all stages of the reaction. Our studies confirm significant dependence of the diffusivity on composition and temperature that elucidate key trends in the available experimental measurements. Whereas at low hydrogen compositions, a single process dominates, atmore » high hydrogen compositions, diffusion is found to exhibit behavior consistent with multiple hopping barriers. Further analysis, supported by nudged elastic band computations, suggests that the multi-barrier diffusion can be interpreted as two distinct mechanisms corresponding to hydrogen-rich and hydrogen-poor local environments.« less

Reinforcement effect of poly(butylene succinate) (PBS)-grafted cellulose nanocrystal on toughened PBS/polylactic acid blends.

PubMed

Zhang, Xuzhen; Zhang, Yong

2016-04-20

Poly(butylene succinate) (PBS)/polylactic acid (PLA) blends modified with dicumyl peroxide (DCP) were reinforced by PBS-g-cellulose nanocrystal (CNC) through melt mixing. PBS-g-CNC was prepared through in situ polymerization and its structure was confirmed by FTIR, (13)C NMR, XPS and GPC analysis after saponification. The morphological analysis of PBS/PLA/PBS-g-CNC composites before and after etched by CH2Cl2 shows that the addition of DCP and PBS-g-CNC could decrease the size of PBS as a dispersed phase in PLA matrix and improve the dispersion of PBS-g-CNC in both PBS and PLA phases, which could affect the crystallization and mechanical properties of composites. The crystallinity of PLA α'-phase crystal in PBS/PLA/PBS-g-CNC composites is increased obviously by the addition of PBS-g-CNC, leading to an increase of the crystallinity of the composites. PBS/PLA blends modified by DCP have high Notched Izod impact strength and moduli, and the values are increased by the addition of PBS-g-CNC. Both storage modulus and glass translation temperature of PBS/PLA blend are increased by DCP and PBS-g-CNC, which is proved by DMA results, showing a weak molecular segment mobility of PBS/PLA matrix. The addition of DCP decreases the crystallization temperature and crystallinity of PBS/PLA composite, but increases the thermal stability of composites, mostly because of the crosslink effect of DCP on PBS/PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Presence of a monoclinic (Pm) phase in the morphotropic phase boundary region of multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution: A Rietveld study

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

Pandey, Rishikesh, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in

2014-07-28

We present here the results of structural studies on multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution using Rietveld analysis on powder x-ray diffraction data in the composition range 0.35 ≤ x ≤ 0.55. The stability region of various crystallographic phases at room temperature for (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} is determined precisely. Structural transformation from pseudo-cubic (x ≤ 0.40) to tetragonal (x ≥ 0.50) phase is observed via phase coexistence region demarcating the morphotropic phase boundary. The morphotropic phase boundary region consists of coexisting tetragonal and monoclinic structures with space group P4mm and Pm, respectively, stable in composition range 0.41 ≤ x ≤ 0.49 as confirmed by Rietveld analysis. The resultsmore » of Rietveld analysis completely rule out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier workers. A comparison between the bond lengths for “B-site cations-oxygen anions” obtained after Rietveld refinement, with the bond length calculated using Shannon-Prewitt ionic radii, reveals the ionic nature of B-O (Ni/Ti-O) bonds for the cubic phase and partial covalent character for the other crystallographic phases.« less

Phenotypic diversity of diploid and haploid Emiliania huxleyi cells and of cells in different growth phases revealed by comparative metabolomics.

PubMed

Mausz, Michaela A; Pohnert, Georg

2015-01-01

In phytoplankton a high species diversity of microalgae co-exists at a given time. But diversity is not only reflected by the species composition. Within these species different life phases as well as different metabolic states can cause additional diversity. One important example is the coccolithophore Emiliania huxleyi. Diploid cells play an important role in marine ecosystems since they can form massively abundant algal blooms but in addition the less abundant haploid life phase of E. huxleyi occurs in lower quantities. Both life phases may fulfill different functions in the plankton. We hypothesize that in addition to the functional diversity caused by this life phase transition the growth stage of cells can also influence the metabolic composition and thus the ecological impact of E. huxleyi. Here we introduce a metabolomic survey in dependence of life phases as well as different growth phases to reveal such changes. The comparative metabolomic approach is based on the extraction of intracellular metabolites from intact microalgae, derivatization and analysis by gas chromatography coupled to mass spectrometry (GC-MS). Automated data processing and statistical analysis using canonical analysis of principal coordinates (CAP) revealed unique metabolic profiles for each life phase. Concerning the correlations of metabolites to growth phases, complex patterns were observed. As for example the saccharide mannitol showed its highest concentration in the exponential phase, whereas fatty acids were correlated to stationary and sterols to declining phase. These results are indicative for specific ecological roles of these stages of E. huxleyi and are discussed in the context of previous physiological and ecological studies. Copyright © 2014 Elsevier GmbH. All rights reserved.

Structural, dielectric and magnetic properties of ZnFe2O4-Na0.5Bi0.5TiO3 multiferroic composites

NASA Astrophysics Data System (ADS)

Bhasin, Tanvi; Agarwal, Ashish; Sanghi, Sujata; Yadav, Manisha; Tuteja, Muskaan; Singh, Jogender; Rani, Sonia

2018-04-01

Multiferroic xNa0.5Bi0.5TiO3-(1-x)ZnFe2O4 (x=0.10, 0.20) composites were prepared by conventional solid state reaction method. Rietveld analysis of XRD data shows that samples exhibit both cubic (Fd-3m) and rhombohedral (R3c) crystal structure. Structural parameters and unit cell volume of samples vary with composition. The dielectric constant and dielectric loss (tanδ) display dispersion at low frequency due to space charge polarization and inhomogeneity in the composites. Magnetic analysis depicts the antiferromagnetic behavior of composites and magnetization is enhanced with the introduction of ferrite (ZnFe2O4) phase.

Fabrication and microstructures of functional gradient SiBCN–Nb composite by hot pressing

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

Sun, Min, E-mail: lcxsunmin@163.com; Fu, Ruoyu; Chen, Jun

2016-04-15

A functional gradient material with five layers composed of SiBCN ceramic and niobium (Nb) was prepared successfully by hot pressing. The phase composition, morphology features and microstructures were investigated in each layer of the gradient material. The Nb-containing compounds involving NbC, Nb{sub 6}C{sub 5}, Nb{sub 4}C{sub 3}, Nb{sub 5}Si{sub 3} and NbN increase with the volume fraction of Nb increasing in the sub-layer. They are randomly scattered (≤ 25 vol.% Nb), then strip-like, and finally distribute continuously (≥ 75 vol.% Nb). The size of BN(C) and SiC grains in Nb-containing layers is larger than in 100% SiBCN layer due tomore » the loss of the capsule-like structures. No distinct interfaces form in the transition regions indicating the gradual changes in phase composition and microstructures. - Highlights: • A functional gradient SiBCN–Nb material was prepared successfully by hot pressing. • Phase composition, morphology features and microstructures were investigated. • Thermodynamic calculation was used to aid in the phase analysis. • No distinct interfaces form typical of the functional gradient material.« less

Investigation of Interrelation between Deformation, Composition and Structural Characteristics of Magnesium Oxychloride Cements

NASA Astrophysics Data System (ADS)

Averina, G. F.; Chernykh, T. N.; Kramar, L. Ya

2017-11-01

The paper studies the process of volume deformation changes in magnesium cement at its hardening in accordance with its composition and structural peculiarities, which result from the roasting parameters of the raw materials. The study has been carried out with the aim of broadening raw materials sources for production of magnesia cements and construction materials through the use waste products of ore-dressing and processing enterprises. The mineralogical and phase composition of magnesium cements, obtained on the basis of magnesite with high content of impurity minerals from the mine dumps, has been studied by the X-ray phase analysis and derivatography. The roasting of the initial raw materials was carried out at various temperature conditions in order to get cements of different activities. The typical content of hydrated phases has been found for the hardened magnesian stone obtained from cements with different activity degrees. The characteristics of volume deformations developed in the magnesian stone have been described in relation to its phase composition. The influence of low- and high-activity crystals and calcium oxide crystals on the soundness and the structural integrity of magnesian stone has been covered.

Phase degradation in BxGa1-xN films grown at low temperature by metalorganic vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Gunning, Brendan P.; Moseley, Michael W.; Koleske, Daniel D.; Allerman, Andrew A.; Lee, Stephen R.

2017-04-01

Using metalorganic vapor phase epitaxy, a comprehensive study of BxGa1-xN growth on GaN and AlN templates is described. BGaN growth at high-temperature and high-pressure results in rough surfaces and poor boron incorporation efficiency, while growth at low-temperature and low-pressure (750-900 °C and 20 Torr) using nitrogen carrier gas results in improved surface morphology and boron incorporation up to 7.4% as determined by nuclear reaction analysis. However, further structural analysis by transmission electron microscopy and x-ray pole figures points to severe degradation of the high boron composition films, into a twinned cubic structure with a high density of stacking faults and little or no room temperature photoluminescence emission. Films with <1% triethylboron (TEB) flow show more intense, narrower x-ray diffraction peaks, near-band-edge photoluminescence emission at 362 nm, and primarily wurtzite-phase structure in the x-ray pole figures. For films with >1% TEB flow, the crystal structure becomes dominated by the cubic phase. Only when the TEB flow is zero (pure GaN), does the cubic phase entirely disappear from the x-ray pole figure, suggesting that under these growth conditions even very low boron compositions lead to mixed crystalline phases.

Facile synthesis and lithium storage properties of a porous NiSi2/Si/carbon composite anode material for lithium-ion batteries.

PubMed

Jia, Haiping; Stock, Christoph; Kloepsch, Richard; He, Xin; Badillo, Juan Pablo; Fromm, Olga; Vortmann, Britta; Winter, Martin; Placke, Tobias

2015-01-28

In this work, a novel, porous structured NiSi2/Si composite material with a core-shell morphology was successfully prepared using a facile ball-milling method. Furthermore, the chemical vapor deposition (CVD) method is deployed to coat the NiSi2/Si phase with a thin carbon layer to further enhance the surface electronic conductivity and to mechanically stabilize the whole composite structure. The morphology and porosity of the composite material was evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption measurements (BJH analysis). The as-prepared composite material consists of NiSi2, silicon, and carbon phases, in which the NiSi2 phase is embedded in a silicon matrix having homogeneously distributed pores, while the surface of this composite is coated with a carbon layer. The electrochemical characterization shows that the porous and core-shell structure of the composite anode material can effectively absorb and buffer the immense volume changes of silicon during the lithiation/delithiation process. The obtained NiSi2/Si/carbon composite anode material displays an outstanding electrochemical performance, which gives a stable capacity of 1272 mAh g(-1) for 200 cycles at a charge/discharge rate of 1C and a good rate capability with a reversible capacity of 740 mAh g(-1) at a rate of 5C.

Glass formation and crystallization in the alumina-silica-lanthanum phosphate system for ceramics composites

NASA Astrophysics Data System (ADS)

Guo, Shuling

The formation, structure, and dynamics of glasses in the alumina-silica-lanthanum phosphate system and their crystallization were investigated as a function of composition. These are of interest because of their potential as precursors for synthesizing ceramic-matrix-composites via co-crystallization of lanthanum monazite and either mullite or alumina into finely mixed microstructures. The glasses were characterized by X-Ray Diffraction (XRD), Raman spectroscopy, Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Electron Energy Loss Spectrometry (EELS). Glass formation from rapidly quenched liquids was easiest and most consistent for compositions containing silica, such as for mullitemonazite compositions, and more difficult for alumina-monazite compositions. For mullite-monazite glasses, the glass transition temperatures increased linearly from 845°C to 906°C with increasing mullite content. An analysis of the glass structure indicated a network consisting of corner-linked aluminate, silicate and phosphate tetrahedra where aluminum played a central role of separating silicon and phosphorous. It was hypothesized that the glass network consisted of domains of aluminum silicate network edged by phosphate tetrahedra. A maximum in the crystallization temperature was attributed to the complexity of the glass network. At relatively mullite-rich compositions, simultaneous and cooperative crystallization of lanthanum phosphate and mullite correlated with the highest crystallization temperatures, and the lowest activation energies of crystallization. This was preceded by amorphous phase segregation in the glass at lower temperatures. An intermediate phase of lanthanum phosphate was discovered with an orthorhombic unit cell. For compositions of high phosphate contents, lanthanum phosphate precipitated first at about 900°C leaving an essentially pure mullite glass. Mullite crystallized at about 1000°C, matching the conditions for crystallizing pure mullite glass. The phosphate phase transformed to monazite at even higher temperatures. No amorphous phase segregation was observed in these cases. Microstructures were correlated with nucleation and growth conditions such that the continuous and isolated phases could be manipulated. Optimum nucleation temperatures were close to the glass transition temperature. Conditions were identified for forming a continuous boundary phase of monazite that isolated mullite grains, which is desired for fabricating ceramic-matrix-composites.

3D Boundary Element Analysis for Composite Joints with discrete Damage. Part 1.

DTIC Science & Technology

1996-11-15

WHS/DIOR, Oct 94 Fracture Analysis Consultants, Inc. 121 Eastern Heights Dr. Ithaca, New York 14850 (607) 257-4970 SBIR Topic AF96 -150 3D Boundary...41 1 F33615-96-C-5070 SBIR Topic AF96 -150: Phase I Final Report Sunmmry Report WL/MLBM solicited Phase I SBIR proposals to develop a capability...materials; no precomputations are required. 2 F33615-96-C-5070 SBIR Topic AF96 -150: Phase I Final Report Task 6. We have developed a fully 3D Galerkin BEM

Thermal analysis and in vitro bioactivity of bioactive glass-alumina composites

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

Chatzistavrou, Xanthippi, E-mail: x.chatzistavrou@imperial.ac.uk; Kantiranis, Nikolaos, E-mail: kantira@geo.auth.gr; Kontonasaki, Eleana, E-mail: kont@dent.auth.gr

2011-01-15

Bioactive glass-alumina composite (BA) pellets were fabricated in the range 95/5-60/40 wt.% respectively and were heat-treated under a specific thermal treatment up to 950 {sup o}C. Control (unheated) and heat-treated pellets were immersed in Simulated Body Fluid (SBF) for bioactivity testing. All pellets before and after immersion in SBF were studied by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM-EDS) and X-ray Diffraction (XRD) analysis. All composite pellets presented bioactive response. On the surface of the heat-treated pellets the development of a rich biological hydroxyapatite (HAp) layer was delayed for one day, compared to the respective control pellets. Independentmore » of the proportion of the two components, all composites of each group (control and heat-treated) presented the same bioactive response as a function of immersion time in SBF. It was found that by the applied methodology, Al{sub 2}O{sub 3} can be successfully applied in bioactive glass composites without obstructing their bioactive response. - Research Highlights: {yields} Isostatically pressed glass-alumina composites presented apatite-forming ability. {yields} The interaction with SBF resulted in an aluminium phosphate phase formation. {yields} The formation of an aluminium phosphate phase enhanced the in vitro apatite growth.« less

Analysis of Long-Range Interaction in Lithium-Ion Battery Electrodes

DOE PAGES

Mistry, Aashutosh; Juarez-Robles, Daniel; Stein, Malcolm; ...

2016-12-01

The lithium-ion battery (LIB) electrode represents a complex porous composite, consisting of multiple phases including active material (AM), conductive additive, and polymeric binder. This study proposes a mesoscale model to probe the effects of the cathode composition, e.g., the ratio of active material, conductive additive, and binder content, on the electrochemical properties and performance. The results reveal a complex nonmonotonic behavior in the effective electrical conductivity as the amount of conductive additive is increased. Insufficient electronic conductivity of the electrode limits the cell operation to lower currents. Once sufficient electron conduction (i.e., percolation) is achieved, the rate performance can bemore » a strong function of ion-blockage effect and pore phase transport resistance. In conclusion, even for the same porosity, different arrangements of the solid phases may lead to notable difference in the cell performance, which highlights the need for accurate microstructural characterization and composite electrode preparation strategies.« less

Analysis of Long-Range Interaction in Lithium-Ion Battery Electrodes

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

Mistry, Aashutosh; Juarez-Robles, Daniel; Stein, Malcolm

The lithium-ion battery (LIB) electrode represents a complex porous composite, consisting of multiple phases including active material (AM), conductive additive, and polymeric binder. This study proposes a mesoscale model to probe the effects of the cathode composition, e.g., the ratio of active material, conductive additive, and binder content, on the electrochemical properties and performance. The results reveal a complex nonmonotonic behavior in the effective electrical conductivity as the amount of conductive additive is increased. Insufficient electronic conductivity of the electrode limits the cell operation to lower currents. Once sufficient electron conduction (i.e., percolation) is achieved, the rate performance can bemore » a strong function of ion-blockage effect and pore phase transport resistance. In conclusion, even for the same porosity, different arrangements of the solid phases may lead to notable difference in the cell performance, which highlights the need for accurate microstructural characterization and composite electrode preparation strategies.« less

Measurement of elastic and thermal properties of composite materials using digital speckle pattern interferometry

NASA Astrophysics Data System (ADS)

Kumar, Manoj; Khan, Gufran S.; Shakher, Chandra

2015-08-01

In the present work, application of digital speckle pattern interferometry (DSPI) was applied for the measurement of mechanical/elastic and thermal properties of fibre reinforced plastics (FRP). Digital speckle pattern interferometric technique was used to characterize the material constants (Poisson's ratio and Young's modulus) of the composite material. Poisson ratio based on plate bending and Young's modulus based on plate vibration of material are measured by using DSPI. In addition to this, the coefficient of thermal expansion of composite material is also measured. To study the thermal strain analysis, a single DSPI fringe pattern is used to extract the phase information by using Riesz transform and the monogenic signal. The phase extraction from a single DSPI fringe pattern by using Riesz transform does not require a phase-shifting system or spatial carrier. The elastic and thermal parameters obtained from DSPI are in close agreement with the theoretical predictions available in literature.

The Effects of Spark-Plasma Sintering (SPS) on the Microstructure and Mechanical Properties of BaTiO3/3Y-TZP Composites

PubMed Central

Li, Jing; Cui, Bencang; Wang, Huining; Lin, Yuanhua; Deng, Xuliang; Li, Ming; Nan, Cewen

2016-01-01

Composite ceramics BaTiO3/3Y-TZP containing 0 mol %, 3 mol %, 5 mol %, 7 mol %, and 10 mol % BaTiO3 have been prepared by conventional sintering and spark-plasma sintering (SPS), respectively. Analysis of the XRD patterns and Raman spectra reveal that the phase composition of t-ZrO2, m-ZrO2, and BaTiO3 has been obtained. Our results indicate that SPS can be effective for the decrease in grain size and porosity compared with conventional sintering, which results in a lower concentration of m-ZrO2 and residual stress. Therefore, the fracture toughness is enhanced by the BaTiO3 phase through the SPS technique, while the behavior was impaired by the piezoelectric second phase through conventional sintering. PMID:28773445

Effect of phase composition of calcium silicate phosphate component on properties of brushite based composite cements

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

Sopcak, T., E-mail: tsopcak@imr.saske.sk; Medvecky, L.; Giretova, M.

The composite cement mixtures were prepared by mixing brushite (B) with, the amorphous hydrated calcium silicate phosphate (CSPH) or annealed calcium silicate phosphate (CSP composed of Si-saturated hydroxyapatite, wollastonite and silica) phases and water as liquid component. The contents of the silicate-phosphate phase in composites were 10.30 and 50 wt%. The significant effect of both the Ca/P ratio and different solubility of calcium silicate phosphate component in starting cement systems on setting time and phase composition of the final composite cements was demonstrated. The compressive strength of the set cements increased with the filler addition and the highest value (~more » 48 MPa) exhibited the 50CSP/B cement composite. The final setting times of the composite cements decreased with the CSPH addition from about 25 to 17 min in 50CSHP/B and setting time of CSP/B composites was around 30 min. The higher content of silica in cements caused the precipitation of fine hydroxyapatite particles in the form of nanoneedles or thin plates perpendicularly oriented to sample surface. The analysis of in vitro cement cytotoxicity demonstrated the strong reduction in cytotoxicity of 10CSPH/B composite with time of cultivation (a low cytotoxicity after 9 days of culture) contrary to cements with higher calcium silicate-phosphate content. These results were attributed to the different surface topography of composite substrates and possible stimulation of cell proliferation by the slow continuously release of ions from 10CSPH/B cement. - Highlights: • Ca/P ratio and solubility of calcium silicate-phosphate components affect the self-setting properties of cements. • Strong relationship between the composite in vitro cytotoxicity and surface microtopography was demonstrated. • Plate-like morphology of coarser particles allowed cells to better adhere and proliferate as compared with nanoneedles.« less

Sintering, thermal stability and mechanical properties of ZrO2-WC composites obtained by pulsed electric current sintering

NASA Astrophysics Data System (ADS)

Huang, Shuigen; Vanmeensel, Kim; van der Biest, Omer; Vleugels, Jozef

2011-03-01

ZrO2-WC composites exhibit comparable mechanical properties as traditional WC-Co materials, which provides an opportunity to partially replace WC-Co for some applications. In this study, 2 mol.% Y2O3 stabilized ZrO2 composites with 40 vol.% WC were consolidated in the 1150°C-1850°C range under a pressure of 60 MPa by pulsed electric current sintering (PECS). The densification behavior, microstructure and phase constitution of the composites were investigated to clarify the role of the sintering temperature on the grain growth, mechanical properties and thermal stability of ZrO2 and WC components. Analysis results indicated that the composites sintered at 1350°C and 1450°C exhibited the highest tetragonal ZrO2 phase transformability, maximum toughness, and hardness and an optimal flexural strength. Chemical reaction of ZrO2 and C, originating from the graphite die, was detected in the composite PECS for 20 min at 1850°C in vacuum.

Lightweight Mg-based composites with thermodynamically stable interfaces by in-situ combustion synthesis

NASA Astrophysics Data System (ADS)

Jo, Ilguk

Lightweight Mg-based composites have been produced by in-situ combustion synthesis of the Al-Ti-C reaction system. The characteristics of the in-situ composites were investigated in terms of phase evolution and interfacial stability using various analysis techniques. The structural analysis results showed that full conversion of the Al-Ti-C reactants into spherical TiC reinforcements with sizes around 1mum was achieved by the combustion reaction. In-situ formed TiC had less oxygen and higher Al contents at the interface than ex-situ formed TiC; these clean interfaces with an Al layer on the reinforcements were shown to yield interfacial stability. For these reasons, the in-situ composites exhibited higher theoretical densities and also good mechanical properties compared with ex-situ produced composites. The interfacial characteristics of molten Mg with the Al-Ti-C reactants and the commercial TiC+Al substrates were evaluated using an infiltration technique under an argon atmosphere. Infiltration length increased with time at temperature, yielding activation energies (Ea) for each system. The value of Ea for the Al-Ti-C system (307.31kJ/mol) is lower than that for the other system (350.84kJ/mol); the high Ea value indicates that the infiltration is not a simple viscosity-controlled phenomenon but involves a chemical reaction. Formation of the Al3Ti phase was observed from the crystal structural analysis of the infiltrated area; thus, existence of reaction promoting the wetting of Mg. The phase evolution, reaction mechanism and kinetics of the Al-Ti-C reaction were studied using DSC and HT-XRD. It was confirmed that, along with the melting of Al, there was formation of Al3Ti by reaction between Al and Ti. A detailed structural analysis indicates that, the reaction mechanism involves melting of Al followed by formation and growth of Al 3Ti, which then contacts the graphite powder and initiates the combustion reaction. The effect of important process parameters, such as the Al content and the reactant sizes, on the microstructure of the resulting in-situ composites is discussed. Feasibility and castability of the composites were investigated by high pressure die casting the composite preforms into automotive parts and durability tests were conducted on the cast parts.

Fractionated-combustion analysis of carbonate-containing phases in composite materials of the hydroxyapatite-calcium carbonate system

NASA Astrophysics Data System (ADS)

Goldberg, M. A.; Shibaeva, T. V.; Smirnov, V. V.; Kutsev, S. V.; Barinov, S. M.; Grigorovich, K. V.

2012-12-01

Materials in the hydroxyapatite (HA)-calcium carbonate (CC) system were synthesized by a precipitation method from aqueous solutions. According to the data of X-ray phase analysis and IR spectroscopy, the powders consisted of CC and AB-type carbonate-substituted HA (CHA). In order to determine the content of carbonate-containing phases in materials, the temperature-temporal mode of fractionated-combustion analysis of carbon was developed. The quantitative phase ratios and the degree of substitution of carbonate groups in CHA were determined. It was shown that the degree of substitution of carbonate groups in CHA increased from 2.47 to 5.31 wt % as the CC content increased from 13.50 to 88.33 wt %.

Laser nitriding of iron: Nitrogen profiles and phases

NASA Astrophysics Data System (ADS)

Illgner, C.; Schaaf, P.; Lieb, K. P.; Schubert, E.; Queitsch, R.; Bergmann, H.-W.

1995-07-01

Armco iron samples were surface nitrided by irradiating them with pulses of an excimer laser in a nitrogen atmosphere. The resulting nitrogen depth profiles measured by Resonant Nuclear Reaction Analysis (RNRA) and the phase formation determined by Conversion Electron Mössbauer Spectroscopy (CEMS) were investigated as functions of energy density and the number of pulses. The nitrogen content of the samples was found to be independent of the number of pulses in a layer of 50 nm from the surface and to increase in depths exceeding 150 nm. The phase composition did not change with the number of pulses. The nitrogen content can be related to an enhanced nitrogen solubility based on high temperatures and high pressures due to the laser-induced plasma above the sample. With increasing pulse energy density, the phase composition changes towards phases with higher nitrogen contents. Nitrogen diffusion seems to be the limiting factor for the nitriding process.

Crystallization studies and dielectric properties of (Ba0.7Sr0.3)TiO3 in bariumaluminosilicate glass

NASA Astrophysics Data System (ADS)

Divya, P. V.; Vignesh, G.; Kumar, V.

2007-12-01

Ferroelectric glass-ceramics with a basic composition (1 - y)(Ba0.70Sr0.30)TiO3 : y(BaO : Al2O3 : 2SiO2) have been synthesized by the sol-gel method. The major crystalline phase is the perovskite. The crystallization of the ferroelectric phase in the glass matrix have been studied using differential thermal analysis and x-ray diffraction and the kinetic parameters characterizing the crystallization have been determined using an Arrhenius model. Glass contents <= 5 mol% promoted liquid phase sintering, which reduced the sintering temperature to 1250 °C. The dielectric permittivity of the glass-ceramic samples decreased and the ferroelectric-paraelectric phase transition became more diffuse with increasing glass content. The dielectric connectivity of the ferroelectric phase in the composite have also been investigated and are reported.

A Groundmass Composition for EET 79001A Using a Novel Microprobe Technique for Estimating Bulk Compositions. Lithology A as an Impact Melt?

NASA Technical Reports Server (NTRS)

Jones, John H.; Hanson, B. Z.

2011-01-01

Petrologic investigation of the shergottites has been hampered by the fact that most of these meteorites are partial cumulates. Two lines of inquiry have been used to evaluate the compositions of parental liquids: (i) perform melting experiments at different pressures and temperatures until the compositions of cumulate crystal cores are reproduced [e.g., 1]; and (ii) use point-counting techniques to reconstruct the compositions of intercumulus liquids [e.g., 2]. The second of these methods is hampered by the approximate nature of the technique. In effect, element maps are used to construct mineral modes; and average mineral compositions are then converted into bulk compositions. This method works well when the mineral phases are homogeneous [3]. However, when minerals are zoned, with narrow rims contributing disproportionately to the mineral volume, this method becomes problematic. Decisions need to be made about the average composition of the various zones within crystals. And, further, the proportions of those zones also need to be defined. We have developed a new microprobe technique to see whether the point-count method of determining intercumulus liquid composition is realistic. In our technique, the approximating decisions of earlier methods are unnecessary because each pixel of our x-ray maps is turned into a complete eleven-element quantitative analysis. The success or failure of our technique can then be determined by experimentation. As discussed earlier, experiments on our point-count composition can then be used to see whether experimental liquidus phases successfully reproduce natural mineral compositions. Regardless of our ultimate outcome in retrieving shergottite parent liquids, we believe our pixel-bypixel analysis technique represents a giant step forward in documenting thin-section modes and compositions. For a third time, we have analyzed the groundmass composition of EET 79001, 68 [Eg]. The first estimate of Eg was made by [4] and later modified by [5], to take phase diagram considerations into account. The Eg composition of [4] was too olivine normative to be the true Eg composition, because the ,68 groundmass contains no forsteritic olivine. A later mapping by [2] basically reconfirmed the modifications of [5]. However, even the modified composition of [5] has olivine on the liquidus for 50 C before low-Ca pyroxene appears [6].

Interlaminar fracture of random short-fiber SMC composite

NASA Technical Reports Server (NTRS)

Wang, S. S.; Suemasu, H.; Zahlan, N. M.

1984-01-01

In the experimental phase of the present study of the interlaminar fracture behavior of a randomly oriented short fiber sheet molding compound (SMC) composite, the double cantilever beam fracture test is used to evaluate the mode I interlaminar fracture toughness of different composite thicknesses. In the analytical phase of this work, a geometrically nonlinear analysis is introduced in order to account for large deflections and nonlinear load deflection curves in the evaluation of interlaminar fracture toughness. For the SMC-R50 material studied, interlaminar toughness is an order of magnitude higher than that of unreinforced neat resin, due to unusual damage mechanisms ahead of the crack tip, together with significant fiber bridging across crack surfaces. Composite thickness effects on interlaminar fracture are noted to be appreciable, and a detailed discussion is given on the influence of SMC microstructure.

Formation of hybrid nanocomposites polymethylolacrylamide/silver

NASA Astrophysics Data System (ADS)

Kolzunova, L. G.; Shchitovskaya, E. V.; Rodzik, I. G.

2018-05-01

In this study, polymethylolacrylamide/silver composites have been formed by incorporating silver nanoparticles into the pre-electrosynthesized polymer film. The composites were formed in a two-step process involving the sorption of silver nitrate by a polymer matrix followed by chemical reduction of Ag-ions. The presence of crystalline silver phase in the polymer was confirmed by X-ray phase analysis (XRD), plasmon resonance and scanning electron microscopy (SEM). The small-angle X-ray scattering (SAXS) method has obtained the distribution functions of silver particles over radii. It is established that the content of silver in composites without chitosan is 10-15 times higher than with its additive. The dependences of cyclic voltammetry in pure phosphate buffer (pH 6.86) and in the presence of hydrogen peroxide were obtained. It has been shown that polymer/silver composites exhibit selectivity to hydrogen peroxide.

Determination of the solubility of tin indium oxide using in situ and ex x-ray diffraction

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

Gonzalez, G. B.; Mason, T. O.; Okasinski, J. S.

A novel approach to determine the thermodynamic solubility of tin in indium oxide via the exsolution from tin overdoped nano-ITO powders is presented. High-energy, in situ and ex situ synchrotron X-ray diffraction was utilized to study the solubility limit at temperatures ranging from 900 C to 1375 C. The tin exsolution from overdoped nanopowders and the formation of In{sub 4}Sn{sub 3}O{sub 12} were observed in situ during the first 4-48 h of high-temperature treatment. Samples annealed between 900 C and 1175 C were also studied ex situ with heat treatments for up to 2060 h. Structural results obtained from Rietveldmore » analysis include compositional phase analysis, atomic positions, and lattice parameters. The tin solubility in In{sub 2}O{sub 3} was determined using the phase analysis compositions from X-ray diffraction and the elemental compositions obtained from X-ray fluorescence. Experimental complications that can lead to incorrect tin solubility values in the literature are discussed.« less

Chemical composition of individual aerosol particles in workplace air during production of manganese alloys.

PubMed

Gunst, S; Weinbruch, S; Wentzel, M; Ortner, H M; Skogstad, A; Hetland, S; Thomassen, Y

2000-02-01

Aerosol particle samples were collected at ELKEM ASA ferromanganese (FeMn) and silicomanganese (SiMn) smelters at Porsgrunn, Norway, during different production steps: raw material mixing, welding of protective steel casings, tapping of FeMn and slag, crane operation moving the ladles with molten metal, operation of the Metal Oxygen Refinement (MOR) reactor and casting of SiMn. Aerosol fractions were assessed for the analysis of the bulk elemental composition as well as for individual particle analysis. The bulk elemental composition was determined by inductively coupled plasma atomic emission spectrometry. For individual particle analysis, an electron microprobe was used in combination with wavelength-dispersive techniques. Most particles show a complex composition and cannot be attributed to a single phase. Therefore, the particles were divided into six groups according to their chemical composition: Group I, particles containing mainly metallic Fe and/or Mn; Group II, slag particles containing mainly Fe and/or Mn oxides; Group III, slag particles consisting predominantly of oxidized flux components such as Si, Al, Mg, Ca, Na and K; Group IV, particles consisting mainly of carbon; Group V, mixtures of particles from Groups II, III and IV; Group VI, mixtures of particles from Groups II and III. In raw material mixing, particles originating from the Mn ores were mostly found. In the welding of steel casings, most particles were assigned to Group II, Mn and Fe oxides. During the tapping of slag and metal, mostly slag particles from Group III were found (oxides of the flux components). During movement of the ladles, most particles came from Group II. At the MOR reactor, most of the particles belonged to the slag phase consisting of the flux components (Group III). The particles collected during the casting of SiMn were mainly attributed to the slag phase (Groups III and V). Due to the compositional complexity of the particles, toxicological investigations on the kinetics of pure compounds may not be easily associated with the results of this study.

Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets

NASA Astrophysics Data System (ADS)

Wyche, K. P.; Monks, P. S.; Smallbone, K. L.; Hamilton, J. F.; Alfarra, M. R.; Rickard, A. R.; McFiggans, G. B.; Jenkin, M. E.; Bloss, W. J.; Ryan, A. C.; Hewitt, C. N.; MacKenzie, A. R.

2015-07-01

Highly non-linear dynamical systems, such as those found in atmospheric chemistry, necessitate hierarchical approaches to both experiment and modelling in order to ultimately identify and achieve fundamental process-understanding in the full open system. Atmospheric simulation chambers comprise an intermediate in complexity, between a classical laboratory experiment and the full, ambient system. As such, they can generate large volumes of difficult-to-interpret data. Here we describe and implement a chemometric dimension reduction methodology for the deconvolution and interpretation of complex gas- and particle-phase composition spectra. The methodology comprises principal component analysis (PCA), hierarchical cluster analysis (HCA) and positive least-squares discriminant analysis (PLS-DA). These methods are, for the first time, applied to simultaneous gas- and particle-phase composition data obtained from a comprehensive series of environmental simulation chamber experiments focused on biogenic volatile organic compound (BVOC) photooxidation and associated secondary organic aerosol (SOA) formation. We primarily investigated the biogenic SOA precursors isoprene, α-pinene, limonene, myrcene, linalool and β-caryophyllene. The chemometric analysis is used to classify the oxidation systems and resultant SOA according to the controlling chemistry and the products formed. Results show that "model" biogenic oxidative systems can be successfully separated and classified according to their oxidation products. Furthermore, a holistic view of results obtained across both the gas- and particle-phases shows the different SOA formation chemistry, initiating in the gas-phase, proceeding to govern the differences between the various BVOC SOA compositions. The results obtained are used to describe the particle composition in the context of the oxidised gas-phase matrix. An extension of the technique, which incorporates into the statistical models data from anthropogenic (i.e. toluene) oxidation and "more realistic" plant mesocosm systems, demonstrates that such an ensemble of chemometric mapping has the potential to be used for the classification of more complex spectra of unknown origin. More specifically, the addition of mesocosm data from fig and birch tree experiments shows that isoprene and monoterpene emitting sources, respectively, can be mapped onto the statistical model structure and their positional vectors can provide insight into their biological sources and controlling oxidative chemistry. The potential to extend the methodology to the analysis of ambient air is discussed using results obtained from a zero-dimensional box model incorporating mechanistic data obtained from the Master Chemical Mechanism (MCMv3.2). Such an extension to analysing ambient air would prove a powerful asset in assisting with the identification of SOA sources and the elucidation of the underlying chemical mechanisms involved.

Structural, morphological and interfacial characterization of Al-Mg/TiC composites

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

Contreras, A.; Angeles-Chavez, C.; Flores, O.

2007-08-15

Morphological and structural characterization of Al-Mg/TiC composites obtained by infiltration process and wetting by the sessile drop technique were studied. Focusing at the interface, wetting of TiC substrates by molten Al-Mg-alloys at 900 deg. C was investigated. Electron probe microanalysis (EPMA) indicated that aluminum carbide (Al{sub 4}C{sub 3}) is formed at the interface and traces of TiAl{sub 3} in the wetting assemblies were detected. Scanning Electron Microscopy (SEM) observations show that TiC particles do not appear to be uniformly attacked to produce a continuous layer of Al{sub 4}C{sub 3} at the interface. Molten Al-Mg-alloys were infiltrated into TiC preforms withmore » flowing argon at a temperature of 900 deg. C. In the composites no reaction phase was observed by SEM. Quantification of the Al phase in the composite was carried out by X-ray diffraction (XRD) and Rietveld analysis. Chemical mapping analyzed by SEM shows that the Al-Mg alloy surrounds TiC particles. In the composites with 20 wt.% of Mg the Al-Mg-{beta} phase was detected through XRD.« less

Effect of particle morphology of Ni on the mechanical behavior of AZ91E-Ni coated nano Al2O3 composites

NASA Astrophysics Data System (ADS)

Sameer Kumar, D.; Suman, K. N. S.; Poddar, Palash

2017-06-01

The properties of any composite always depend on the bonding between the matrix and reinforcement phases. One way of improving the wettability of reinforcement in a matrix is to apply a layer of coating on reinforcing particles. The present study aims at developing Ni coating on nano Al2O3 ceramic particles and dispersing them in AZ91E magnesium matrix material. The electroless plating method has been employed to coat the particles and semi solid stir casting technique was adopted to prepare the composites. Several weight fractions of dispersed phase are considered to analyze the behavior of the fabricated composites. Field emission scanning electron microscopy (FESEM) and x-ray diffraction analysis has been carried out to investigate the distribution of particles and phase characteristics of the proposed material. The physical and mechanical behavior of the material was examined through density measurements, hardness, elastic modulus, ductility and tensile strength calculations. The metal coating on reinforcement aids to promote metal-metal bonding interface reactions which result in improved properties of the composite. Tensile fractography was carried out under FESEM and presented.

Preferential adsorption of fluorescing fulvic and humic acid components on activated carbon using flow field-flow fractionation analysis.

PubMed

Schmit, Kathryn H; Wells, Martha J M

2002-02-01

Activated carbon treatment of drinking water is used to remove natural organic matter (NOM) precursors that lead to the formation of disinfection byproducts. The innate hydrophobic nature and macromolecular size of NOM render it amenable to sorption by activated carbon. Batch equilibrium and minicolumn breakthrough adsorption studies were performed using granular activated carbon to treat NOM-contaminated water. Ultraviolet (UV) absorption spectroscopy and flow field-flow fractionation analysis using tandem diode-array and fluorescence detectors were used to monitor the activated carbon sorption of NOM. Using these techniques, it was possible to study activated carbon adsorption properties of UV absorbing, fluorescing and nonfluorescing, polyelectrolytic macromolecules fractionated from the total macromolecular and nonmacromolecular composition of NOM. Adsorption isotherms were constructed at pH 6 and pH 9. Data were described by the traditional and modified Freundlich models. Activated carbon capacity and adsorbability were compared among fractionated molecular subsets of fulvic and humic acids. Preferential adsorption (or adsorptive fractionation) of polyelectrolytic, fluorescing fulvic and humic macromolecules on activated carbon was observed. The significance of observing preferential adsorption on activated carbon of fluorescing macromolecular components relative to nonfluorescing components is that this phenomenon changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the composition that existed in the aqueous phase prior to adsorption. Likewise, it changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the adsorbed phase. This research increases our understanding of NOM interactions with activated carbon which may lead to improved methods of potable water production.

LIFE CYCLE DESIGN OF AIR INTAKE MANIFOLDS; PHASE I: 2.0 L FORD CONTOUR AIR INTAKE MANIFOLD

EPA Science Inventory

The project team applied the life cycle design methodology to the design analysis of three alternative air intake manifolds: a sand cast aluminum, brazed aluminum tubular, and nylon composite. The design analysis included a life cycle inventory analysis, environmental regulatory...

Thermal Properties of Zeolite-Containing Composites

PubMed Central

Shimonosono, Taro; Hirata, Yoshihiro; Nishikawa, Kyohei; Sameshima, Soichiro; Sodeyama, Kenichi; Masunaga, Takuro; Yoshimura, Yukio

2018-01-01

A zeolite (mordenite)–pore–phenol resin composite and a zeolite–pore–shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is useful for a zeolite powder with no sinterability to clarify its thermal properties. At a low porosity <20%, the thermal conductivity of the composite was in excellent agreement with the calculated value for the structure with phenol resin or shirasu glass continuous phase. At a higher porosity above 40%, the measured value approached the calculated value for the structure with pore continuous phase. The thermal conductivity of the monolithic mordenite was evaluated to be 3.63 W/mK and 1.70–2.07 W/mK at room temperature for the zeolite–pore–phenol resin composite and the zeolite–pore–shirasu glass composite, respectively. The analyzed thermal conductivities of monolithic mordenite showed a minimum value of 1.23 W/mK at 400 °C and increased to 2.51 W/mK at 800 °C. PMID:29534034

Direct mass spectrometry approaches to characterize polyphenol composition of complex samples.

PubMed

Fulcrand, Hélène; Mané, Carine; Preys, Sébastien; Mazerolles, Gérard; Bouchut, Claire; Mazauric, Jean-Paul; Souquet, Jean-Marc; Meudec, Emmanuelle; Li, Yan; Cole, Richard B; Cheynier, Véronique

2008-12-01

Lower molecular weight polyphenols including proanthocyanidin oligomers can be analyzed after HPLC separation on either reversed-phase or normal phase columns. However, these techniques are time consuming and can have poor resolution as polymer chain length and structural diversity increase. The detection of higher molecular weight compounds, as well as the determination of molecular weight distributions, remain major challenges in polyphenol analysis. Approaches based on direct mass spectrometry (MS) analysis that are proposed to help overcome these problems are reviewed. Thus, direct flow injection electrospray ionization mass spectrometry analysis can be used to establish polyphenol fingerprints of complex extracts such as in wine. This technique enabled discrimination of samples on the basis of their phenolic (i.e. anthocyanin, phenolic acid and flavan-3-ol) compositions, but larger oligomers and polymers were poorly detectable. Detection of higher molecular weight proanthocyanidins was also restricted with matrix-assisted laser desorption ionization (MALDI) MS, suggesting that they are difficult to desorb as gas-phase ions. The mass distribution of polymeric fractions could, however, be determined by analyzing the mass distributions of bovine serum albumin/proanthocyanidin complexes using MALDI-TOF-MS.

Synergetic effect at the interfaces of solution processed MoS2-WS2 composite for hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Kim, Seong Ku; Song, Wooseok; Ji, Seulgi; Lim, Yi Rang; Lee, Young Bum; Myung, Sung; Lim, Jongsun; An, Ki-Seok; Lee, Sun Sook

2017-12-01

Recently, the importance of developing an effective catalyst for hydrogen evolution reaction is emphasized because hydrogen fueled energy conversion processes are gaining attention as the next generation energy production method. We propose a transition metal dichalcogenide composite catalyst based on molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on reduced graphene oxide coated nickel (rGO-Ni) foams. The composite exhibited enhanced catalytic activity with observed on-set potential of ∼275 mV at -10 mA/cm2 and Tafel slope of 54.1 mV/dec when the composition of the composite was 50%MoS2-50%WS2. The composite catalyst demonstrated high-stability up to 300 cycles. In order to understand the enhanced catalytic activity, X-ray photoelectron spectroscopy compositional analysis was utilized. We propose that the enhancement of catalytic activities exhibited by the composited samples were achieved due to introduction of new type of interface between MoS2 and WS2 grains, regional transition of 2H phase MoS2 and WS2 to 1T phase, and formation of excess sulfur which depended directly on the composition.

Analysis of the FF Aqr spectra

NASA Astrophysics Data System (ADS)

Shimanskaya, N. N.; Bikmaev, I. F.; Shimansky, V. V.

2011-07-01

We determine the atmospheric parameters of the secondary in the close binary system FF Aqr and analyze its chemical composition. A series of high-resolution spectra are taken at different orbital phases using the coude echelle spectrometer of the 1.5-m Russian-Turkish Telescope (RTT150). We show that the absorption line intensity of heavy elements varies with phase due to the spotty nature of the cool component. We determine the abundances of heavy elements in the star's atmosphere by modelling the synthetic spectra and performing a differential analysis of the chemical composition of FF Aqr relative to the solar composition. Our analysis of the averaged spectrum of FF Aqr yielded 539 abundance estimates for 21 chemical elements. We found the metallicity of the star ([ Fe/H] = -0.11 ± 0.08) to be close solar, in agreement with the hypothesis that FF Aqr should belong to the Galactic disk. The inferred chemical composition of the objects exhibits no anomalous abundances of the α-, r-, and s-process elements like those earlier found in other systems (IN Com, LW Hya, V471 Tau). The lack of such anomalies in FF Aqr must be due to the fact that the elements heavier than 16 O cannot be synthesized in the core of the primary during the last stages of its evolution.

Phase relationship in three-phase composites which include a void phase

NASA Technical Reports Server (NTRS)

Price, H. L.; Nelson, J. B.

1976-01-01

The paper shows the relationship among polymer, particles, and voids in a three-phase composite and how some of the properties of a composite may be changed by changing the proportions of the phases. The three-phase composite is an aggregate of microspheres bonded together with a small amount of polymer which may not form a continuous matrix. The void space (third phase) is obtained by limiting the amount of polymer which is mixed with the microspheres. A ternary phase diagram is used to show the proportional relationship among the three phases, with each apex representing a volume fraction of unity for a constituent while the side opposite the apex represents a volume fraction of zero for that constituent. The vertical dimension represents some composite property such as density or strength. The effect of composition on composite properties is shown by plotting them on a binary phase diagram which represents a perpendicular plane coincident with the 0.60 volume fraction microsphere line.

Analysis of phase transformations in Inconel 738C alloy after regenerative heat treatment

NASA Astrophysics Data System (ADS)

Kazantseva, N.; Davidov, D.; Vinogradova, N.; Ezhov, I.; Stepanova, N.

2018-03-01

Study is based on the characterization of the chemical composition the phase transformations in Inconel 738C gas turbine blade after standard regenerative heat treatment. The microstructure and chemical composition were examined by scanning electron microscope and transmission electron microscope equipped with an energy dispersive X-ray spectrometer. It was found the degradation of microstructure of the blade feather. Redistribution of the chemical elements decreasing the corrosion resistance was observed inside the blade feather. The carbide transformation and sigma phase were found in the structure of the blade feather. It is found that the standard regenerative heat treatment of the IN738 operative gas turbine blade does not effect on carbides transformation, TCP σ-phase dissolution, and thus do not guarantee the full recovery of the IN738 gas turbine blade.

Elemental composition and structural characteristics of as-received TriTaniumTM orthodontic archwire

NASA Astrophysics Data System (ADS)

Ilievska, I.; Petrov, V.; Mihailov, V.; Karatodorov, S.; Andreeva, L.; Zaleski, A.; Mikli, V.; Gueorgieva, M.; Petrova, V.; Stoyanova-Ivanova, A.

2018-03-01

Orthodontic archwires are among the most important devices of fixed orthodontic therapy. Many types of archwires are made available on the market by various manufacturers with different elemental composition and structural characteristics. Knowing this information is important when choosing a suitable archwire for a particular stage of orthodontic treatment. The aim of our study is to characterize a new type orthodontic archwires (TriTaniumTM, American Orthodontics) before their placement in the oral cavity. To achieve the aim, we used modern methods for determining their elemental composition and structural characteristics: laser-induced plasma spectroscopy (LIBS), X-ray diffraction analysis (XRD), scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and differential scanning calorimetry (DSC). The results obtained from the qualitative elemental analysis by LIBS and the quantitative elemental analysis by EDX showed that Ni and Ti are the main elements in the archwire studied. The room-temperature XRD patterns showed peaks typical for a Ni-Ti alloy with an austenite-type structure. Monitoring the phase transitions by means of DSC measurements in the temperature range from –50 °C to +50 °C, we showed that in TriTaniumTM archwires, besides the austenite to martensite transition, there exists a rhombohedral intermediate phase (R phase). This study will be useful in assisting orthodontists in applying appropriate nickel-titanium orthodontic archwires in the clinical practice.

Influence of frequency on the structure of zirconium oxide coatings deposited from aqueous electrolytes under microplasma oxidation

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

Gubaidulina, Tatiana A., E-mail: goub2002@mail.ru; Sergeev, Viktor P., E-mail: vserg@mail.tomsknet.ru; Fedorischeva, Marina V., E-mail: fmw@ispms.tsc.ru

2015-10-27

The work describes the microplasma oxidation (MPO) of zirconium surface resulting in the formation of zirconium oxide Zr-Al-Nb-O. We have used novel power supply to deposit oxide ceramic coatings by MPO and studied the effect of current density on the phase structure of oxide ceramic coatings. The size of microcracks in the coatings was determined at different frequencies. We have also used EVO50c scanning election microscope with an attachment for elemental analysis to study the morphology and elemental composition of oxide ceramic coating. In addition, we have established the influence of the frequency on the phase composition of the coating:more » at the frequency of 2500 Hz, the fraction of monoclinic phase was 18%, while the fraction of tetragonal phase amounted to 72%. The oxide ceramic coating produced at 250 Hz contained 38% of monoclinic phase and 62% of tetragonal phase; in addition, it had no buildups and craters.« less

β-Ga2O3 versus ε-Ga2O3: Control of the crystal phase composition of gallium oxide thin film prepared by metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Zhuo, Yi; Chen, Zimin; Tu, Wenbin; Ma, Xuejin; Pei, Yanli; Wang, Gang

2017-10-01

Gallium oxide thin films of β and ε phase were grown on c-plane sapphire using metal-organic chemical vapor deposition and the phase compositions were analyzed using X-ray diffraction. The epitaxial phase diagram was constructed as a function of the growth temperature and VI/III ratio. A low growth temperature and low VI/III ratio were beneficial for the formation of hexagonal-type ε-Ga2O3. Further structure analysis revealed that the epitaxial relationship between ε-Ga2O3 and c-plane sapphire is ε-Ga2O3 (0001) || Al2O3 (0001) and ε-Ga2O3 || Al2O3 . The structural evolution of the mixed-phase sample during film thickening was investigated. By reducing the growth rate, the film evolved from a mixed phase to the energetically favored ε phase. Based on these results, a Ga2O3 thin film with a phase-pure ε-Ga2O3 upper layer was successfully obtained.

LCD OF AIR INTAKE MANIFOLDS PHASE 2: FORD F250 AIR INTAKE MANIFOLD

EPA Science Inventory

The life cycle design methodology was applied to the design analysis of three alternatives for the lower plehum of the air intake manifold for us with a 5.4L F-250 truck engine: a sand cast aluminum, a lost core molded nylon composite, and a vibration welded nylon composite. The ...

Body composition and phase angle in Russian children in remission from acute lymphoblastic leukemia

NASA Astrophysics Data System (ADS)

Tseytlin, G. Ja; Khomyakova, I. A.; Nikolaev, D. V.; Konovalova, M. V.; Vashura, A. Yu; Tretyak, A. V.; Godina, E. Z.; Rudnev, S. G.

2010-04-01

Elevated degree of body fatness and changes in other body composition parameters are known to be common effects of treatment for acute lymphoblastic leukemia (ALL) in children. In order to study peculiarities of somatic growth and development in ALL survivors, we describe the results of BIA body composition analysis of 112 boys and 108 girls aged 5-18 years in remission from ALL (remission time range 1-13 years) compared to data from the same number of age- and sex-matched healthy controls (n=220). Detrimental effect on height in ALL boys was observed, whereas girls experienced additional weight gain compared to healthy subjects. In ALL patients, resistance, body fat, and percent body fat were significantly increased. The reactance, phase angle, absolute and relative values of skeletal muscle and body cell mass were significantly decreased. Principal component analysis revealed an early prevalence of adiposity traits in the somatic growth and development of ALL girls compared to healthy controls.

Influence of Carbon Nanotubes on the Structure Formation of Cement Matrix

NASA Astrophysics Data System (ADS)

Petrunin, S.; Vaganov, V.; Reshetniak, V.; Zakrevskaya, L.

2015-11-01

The potential of application of CNTs as a reinforcing agent in cement composites is governed by their unique mechanical and electronic properties. The analysis of concrete strength changes under CNTs introduction shows non-uniformity and sometimes inconsistency of results. Due to the fact that CNTs influence the hydration kinetics, structure and phase composition of concrete, an idea concerning the importance of interaction between the surface of CNTs and hydrate ions formed by the dissolution of the clinker phases has been suggested. In this paper, the theoretical and experimental study of interaction between hydrate ions and CNTs surface is discussed. Reference nanotubes and nanotubes functionalized by carboxylic groups are used in this research. Phase composition was determined by X-Ray analysis according to the Rietveld method. It was found that the presence of oxygen-containing functional groups on CNTs surface leads to intensification of the hydration process and increase in concentration of C-S-H gel from 65.9% to 74.4%. Special attention is usually paid to interactions between Ca2+ ions and CNTs, because the hardening rate and structure of cement stone are determined by principle of Ca2+ localization in the solution. In this paper the possible binding mechanisms are discussed. Based on the experimental results, the hypothesis regarding the formation of cement composite structure for different CNTs surface functionalizations is considered. According to this hypothesis, the CNTs act as the centers of crystallization for hydration products contributing to the acceleration of hydration, increase of the concentration of C-S-H gel and strength improvement of CNTs based composites.

Effect of Sr addition on the microstructure and mechanical properties of ADC12/nano Al2O3 composites produced by stir casting method

NASA Astrophysics Data System (ADS)

Syahrial, Anne Zulfia; Puspita, Lalita Padma; Dhaneswara, Donanta; Utomo, Budi Wahyu

2018-05-01

The effects of Sr addition on microstructure and mechanical properties of ADC12/nano Al2O3 composite has been studied. In this research ADC12 as a matrix was added by 0.3 vf% nano Al2O3 as a reinforcement and Al-5Sr varied from 0.00 wt% to 0.05 wt% to modify the eutectic structure of the matrix. The composites were further characterized both microstructural analysis and mechanical properties. The results showed that the intermetallic phases including β-Al5FeSi and Al2Cu were detected using scanning electron microscope and α-Al(Mn,Fe)Si or α-cubic phases was possible to form due to high content of Mn in the composites. The Mg2Si primary, binary, and ternary phases were detected in this composites by metallographic examination. Then, MgAl2O4 (spinnel) were found by XRD analysis. The higher of Sr content from 0,00 to 0.02 the lower SDAS formation from 15 µm to 14 µm as well as porosity content reduced from 4% to 3%. The ultimate tensile strength increased from 115 MPa to 137 MPa as well as in impact toughness from 0.016 J/mm2 to 0.025 J/mm2. The highest hardness and the lowest wear rate were obtained with the addition of 0.05 wt% Sr with 46 HRB and 1.04 10-5 mm3/m respectively due to the changed of chinese script became refined fibrous type.

Phase degradation in B xGa 1–xN films grown at low temperature by metalorganic vapor phase epitaxy

DOE PAGES

Gunning, Brendan P.; Moseley, Michael W.; Koleske, Daniel D.; ...

2016-11-01

Using metalorganic vapor phase epitaxy, a comprehensive study of B xGa 1-xN growth on GaN and AlN templates is described. BGaN growth at high-temperature and high-pressure results in rough surfaces and poor boron incorporation efficiency, while growth at low-temperature and low-pressure (750–900 °C and 20 Torr) using nitrogen carrier gas results in improved surface morphology and boron incorporation up to ~7.4% as determined by nuclear reaction analysis. However, further structural analysis by transmission electron microscopy and x-ray pole figures points to severe degradation of the high boron composition films, into a twinned cubic structure with a high density of stackingmore » faults and little or no room temperature photoluminescence emission. Films with <1% triethylboron (TEB) flow show more intense, narrower x-ray diffraction peaks, near-band-edge photoluminescence emission at ~362 nm, and primarily wurtzite-phase structure in the x-ray pole figures. For films with >1% TEB flow, the crystal structure becomes dominated by the cubic phase. As a result, only when the TEB flow is zero (pure GaN), does the cubic phase entirely disappear from the x-ray pole figure, suggesting that under these growth conditions even very low boron compositions lead to mixed crystalline phases.« less

Phase degradation in B xGa 1–xN films grown at low temperature by metalorganic vapor phase epitaxy

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

Gunning, Brendan P.; Moseley, Michael W.; Koleske, Daniel D.

Using metalorganic vapor phase epitaxy, a comprehensive study of B xGa 1-xN growth on GaN and AlN templates is described. BGaN growth at high-temperature and high-pressure results in rough surfaces and poor boron incorporation efficiency, while growth at low-temperature and low-pressure (750–900 °C and 20 Torr) using nitrogen carrier gas results in improved surface morphology and boron incorporation up to ~7.4% as determined by nuclear reaction analysis. However, further structural analysis by transmission electron microscopy and x-ray pole figures points to severe degradation of the high boron composition films, into a twinned cubic structure with a high density of stackingmore » faults and little or no room temperature photoluminescence emission. Films with <1% triethylboron (TEB) flow show more intense, narrower x-ray diffraction peaks, near-band-edge photoluminescence emission at ~362 nm, and primarily wurtzite-phase structure in the x-ray pole figures. For films with >1% TEB flow, the crystal structure becomes dominated by the cubic phase. As a result, only when the TEB flow is zero (pure GaN), does the cubic phase entirely disappear from the x-ray pole figure, suggesting that under these growth conditions even very low boron compositions lead to mixed crystalline phases.« less

Compositionally driven giant strain and electrostrictive co-efficient in lead free NBT-BT-BFO system

NASA Astrophysics Data System (ADS)

Duraisamy, Dhayanithi; Venkatesan, Giridharan Nambi

2018-01-01

As lead free alternatives, bismuth based ferroelectric ceramics are currently under intense investigation. Here, the authors report on the development of a lead free (1-2x)Na0.5Bi0.5TiO3-xBaTiO3-xBiFeO3: NBT-BT-BFO [x = 0.01, 0.03, 0.05, 0.07, and 0.09] ceramic. Rietveld analysis of the powder diffraction data reveals the existence of compositionally driven single and two phase combinations. The compositions corresponding to x = 0.01 and 0.03 are found to be crystallized in a monoclinic (Cc) system, whereas the compositions corresponding to x =0.05, 0.07, and 0.09 are found to have the coexistence of [monoclinic (Cc) + Cubic (pm-3m)] and [Tetragonal (P4bm) + Cubic (pm-3m)] phases. A high electric field induced strain has been obtained for x = 0.07, which can be attributed to the polarization extension mechanism at the proximity of the phase boundary between polar and nonpolar phases. Further, the manufactured ceramic is characterized by Smax/Emax of 858 pm/V and an electrostrictive co-efficient (Q33) of 0.045 m4 C-2 much higher than the values of well-established Pb(Zr,Ti)O3 and other lead free ceramics.

Micromechanics of metal matrix composites using the Generalized Method of Cells model (GMC) user's guide

NASA Technical Reports Server (NTRS)

Aboudi, Jacob; Pindera, Marek-Jerzy

1992-01-01

A user's guide for the program gmc.f is presented. The program is based on the generalized method of cells model (GMC) which is capable via a micromechanical analysis, of predicting the overall, inelastic behavior of unidirectional, multi-phase composites from the knowledge of the properties of the viscoplastic constituents. In particular, the program is sufficiently general to predict the response of unidirectional composites having variable fiber shapes and arrays.

Material State Awareness for Composites Part I: Precursor Damage Analysis Using Ultrasonic Guided Coda Wave Interferometry (CWI).

PubMed

Patra, Subir; Banerjee, Sourav

2017-12-16

Detection of precursor damage followed by the quantification of the degraded material properties could lead to more accurate progressive failure models for composite materials. However, such information is not readily available. In composite materials, the precursor damages-for example matrix cracking, microcracks, voids, interlaminar pre-delamination crack joining matrix cracks, fiber micro-buckling, local fiber breakage, local debonding, etc.-are insensitive to the low-frequency ultrasonic guided-wave-based online nondestructive evaluation (NDE) or Structural Health Monitoring (SHM) (~100-~500 kHz) systems. Overcoming this barrier, in this article, an online ultrasonic technique is proposed using the coda part of the guided wave signal, which is often neglected. Although the first-arrival wave packets that contain the fundamental guided Lamb wave modes are unaltered, the coda wave packets however carry significant information about the precursor events with predictable phase shifts. The Taylor-series-based modified Coda Wave Interferometry (CWI) technique is proposed to quantify the stretch parameter to compensate the phase shifts in the coda wave as a result of precursor damage in composites. The CWI analysis was performed on five woven composite-fiber-reinforced-laminate specimens, and the precursor events were identified. Next, the precursor damage states were verified using high-frequency Scanning Acoustic Microscopy (SAM) and optical microscopy imaging.

Supercritical Fluid Chromatography of Drugs: Parallel Factor Analysis for Column Testing in a Wide Range of Operational Conditions

PubMed Central

Al-Degs, Yahya; Andri, Bertyl; Thiébaut, Didier; Vial, Jérôme

2017-01-01

Retention mechanisms involved in supercritical fluid chromatography (SFC) are influenced by interdependent parameters (temperature, pressure, chemistry of the mobile phase, and nature of the stationary phase), a complexity which makes the selection of a proper stationary phase for a given separation a challenging step. For the first time in SFC studies, Parallel Factor Analysis (PARAFAC) was employed to evaluate the chromatographic behavior of eight different stationary phases in a wide range of chromatographic conditions (temperature, pressure, and gradient elution composition). Design of Experiment was used to optimize experiments involving 14 pharmaceutical compounds present in biological and/or environmental samples and with dissimilar physicochemical properties. The results showed the superiority of PARAFAC for the analysis of the three-way (column × drug × condition) data array over unfolding the multiway array to matrices and performing several classical principal component analyses. Thanks to the PARAFAC components, similarity in columns' function, chromatographic trend of drugs, and correlation between separation conditions could be simply depicted: columns were grouped according to their H-bonding forces, while gradient composition was dominating for condition classification. Also, the number of drugs could be efficiently reduced for columns classification as some of them exhibited a similar behavior, as shown by hierarchical clustering based on PARAFAC components. PMID:28695040

Scalable and Tunable Carbide-Phosphide Composite Catalyst System for the Thermochemical Conversion of Biomass

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

Regmi, Yagya; Rogers, Bridget; Labbe, Nicole

We have prepared composite materials of hexagonal nickel phosphide and molybdenum carbide (Mo2C) utilizing a simple and scalable two-stage synthesis method comprised of carbothermic reduction followed by hydrothermal incubation. We observe the monophasic hexagonal phosphide Ni2P in the composite at low phosphide-to-carbide (P:C) ratios. Upon increasing the proportion of P:C, the carbide surface becomes saturated, and we detect the emergence of a second hexagonal nickel phosphide phase (Ni5P4) upon annealing. We demonstrate that vapor-phase upgrading (VPU) of whole biomass via catalytic fast pyrolysis is achievable using the composite material as a catalyst, and we monitor the resulting product slates usingmore » pyrolysis gas chromatography/mass spectrometry. Our analysis of the product vapors indicates that variation of the P:C molar ratio in the composite material affords product slates of varying complexity and composition, which is indicated by the number of products and their relative proportions in the product slate. Our results demonstrate that targeted vapor product composition can be obtained, which can potentially be utilized to tune the composition of the bio-oil downstream.« less

Scalable and Tunable Carbide-Phosphide Composite Catalyst System for the Thermochemical Conversion of Biomass

DOE PAGES

Regmi, Yagya; Rogers, Bridget; Labbe, Nicole; ...

2017-07-13

We have prepared composite materials of hexagonal nickel phosphide and molybdenum carbide (Mo2C) utilizing a simple and scalable two-stage synthesis method comprised of carbothermic reduction followed by hydrothermal incubation. We observe the monophasic hexagonal phosphide Ni2P in the composite at low phosphide-to-carbide (P:C) ratios. Upon increasing the proportion of P:C, the carbide surface becomes saturated, and we detect the emergence of a second hexagonal nickel phosphide phase (Ni5P4) upon annealing. We demonstrate that vapor-phase upgrading (VPU) of whole biomass via catalytic fast pyrolysis is achievable using the composite material as a catalyst, and we monitor the resulting product slates usingmore » pyrolysis gas chromatography/mass spectrometry. Our analysis of the product vapors indicates that variation of the P:C molar ratio in the composite material affords product slates of varying complexity and composition, which is indicated by the number of products and their relative proportions in the product slate. Our results demonstrate that targeted vapor product composition can be obtained, which can potentially be utilized to tune the composition of the bio-oil downstream.« less

Comparison of mechanical and friction properties of composite materials based on AlMg2 containing nano-dimensional particles of crystalline graphite and nanofibers of gamma oxide of aluminum

NASA Astrophysics Data System (ADS)

Aborkin, A. V.; Babin, D. M.; Soboĺkov, A. V.

2018-04-01

The method of mechanical synthesis in a planetary ball mill was used for production of composite powders based on the AlMg2 alloy containing 1 wt. % of nanosized particles of crystalline graphite or γ-Al2O3. The resulting powders are consolidated by the sintering under pressure. Using the methods of X-ray diffraction analysis, scanning and transmission electron microscopy, the structural-phase composition of bulk composite materials was studied. Comparative analysis of the microhardness, the conditional yield stress at compression, and the friction coefficient of bulk composite materials is carried out. It has been found out that the mechanical properties of composites reinforced with γ-Al2O3 nanofibers are higher than when reinforcing with nanoscale particles of crystalline graphite.

Observing Tin-Lead Alloys by Scanning Electron Microscopy: A Physical Chemistry Experiment Investigating Macro-Level Behaviors and Micro-Level Structures

ERIC Educational Resources Information Center

Wang, Yue; Xu, Xinhua; Wu, Meifen; Hu, Huikang; Wang, Xiaogang

2015-01-01

Scanning electron microscopy (SEM) was introduced into undergraduate physical chemistry laboratory curriculum to help students observe the phase composition and morphology characteristics of tin-lead alloys and thus further their understanding of binary alloy phase diagrams. The students were captivated by this visual analysis method, which…

Analysis of effluent after anaerobic digestion of liquid phase separated from liquidized garbage.

PubMed

Inoue, Seiichi; Tsukahara, Kenichiro; Sawayama, Shigeki

2002-01-01

The organic compositions of the liquid phase separated from liquidized garbage as the influent and its effluent after anaerobic digestion at an overloading rate were analyzed. A large amount of organic acids was found in the effluent. The accumulation of organic acids suggests that the rate of methanogenesis is lower than that of acidogenesis.

Effect of TiN coating on microstructure of Tif/Al composite.

PubMed

Xiu, Z Y; Chen, G Q; Wang, M; Hussain, Murid

2013-02-01

In the present work, Ti fibre reinforced Al matrix composites (Ti(f)/Al) were fabricated by pressure infiltration method. In order to suppress the severe Ti-Al reaction and reduce the formation of brittle TiAl(3) phase, a TiN layer was coated on Ti fibres by an arc ion plating method before composite preparation. A thin TiN layer was coated on the Ti fibre surface, and the maximum and minimum thickness values of layer were about 3.5 and 1μm, respectively. Prefer orientation of TiN on (111) and (200) was found by XRD analysis. A thin and uniform TiAl(3) layer was observed in Ti(f)/Al composite. However, after coated with TiN layer, no significant reaction layer was found in (Ti(f)+TiN)/Al composite. Segregation of Mg element was found in Ti(f)/Al composite, and the presence of TiN layer showed little effect on this behaviour. Due to the large CTE difference between Ti fibre and Al matrix, high density dislocations were observed in the Al matrix. Meanwhile, fine dispersed Mg(2)Al(3) phases were also found in Al matrix. Ti fibre is mainly composed of α- and β-Ti. Small discontinuous needle-like TiAl(3) phases were detected at TiN/Al interface, which implies that the presence of TiN layer between the Ti fibre and Al matrix could effectively hinder the formation of TiAl(3) phases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Synthesis and characterization of bulk metallic glasses prepared by laser direct deposition

NASA Astrophysics Data System (ADS)

Ye, Xiaoyang

Fe-based and Zr-based metallic glasses have attracted extensive interest for structural applications due to their excellent glass forming ability, superior mechanical properties, unique thermal and corrosion properties. In this study, the feasibility of synthesizing metallic glasses with good ductility by laser direct deposition is explored. Both in-situ synthesis with elemental powder mixture and ex-situ synthesis with prealloyed powder are discussed. Microstructure and properties of laser direct deposited metallic glass composites are analyzed. Synthesis of Fe-Cr-Mo-W-Mn-C-Si-B metallic glass composite with a large fraction of amorphous phase was accomplished using laser direct deposition. X-ray diffraction (XRD) and transmission electron microscopy investigations revealed the existence of amorphous structure. Microstructure analyses by optical microscopy and scanning electron microscopy (SEM) indicated the periodically repeated microstructures of amorphous and crystalline phases. Partially crystallized structure brought by laser reheating and remelting during subsequent laser scans aggregated in the overlapping area between each scan. XRD analysis showed that the crystalline particle embedded in the amorphous matrix was Cr 1.07Fe18.93 phase. No significant microstructural differences were found from the first to the last layer. Microhardness of the amorphous phase (HV0.2 1591) showed a much higher value than that of the crystalline phase (HV0.2 947). Macrohardness of the top layer had a value close to the microhardness of the amorphous region. Wear resistance property of deposited layers showed a significant improvement with the increased fraction of amorphous phase. Zr65Al10Ni10Cu15 amorphous composites with a large fraction of amorphous phase were in-situ synthesized by laser direct deposition. X-ray diffraction confirmed the existence of both amorphous and crystalline phases. Laser parameters were optimized in order to increase the fraction of amorphous phase. The microstructure analysis by scanning electron microscopy revealed the deposited structure was composed of periodically repeated amorphous and crystalline phases. Overlapping regions with nanoparticles aggregated were crystallized by laser reheating and remelting processes during subsequent laser scans. Vickers microhardness of the amorphous region showed around 35% higher than that of crystalline region. Average hardness obtained by a Rockwell macrohardness tester was very close to the microhardness of the amorphous region. The compression test showed that the fracture strain of Zr65Al10Ni10Cu15 amorphous composites was enhanced from less than 2% to as high as 5.7%, compared with fully amorphous metallic glass. Differential scanning calorimetry test results further revealed the amorphous structure and glass transition temperature Tg was observed to be around 655K. In 3 mol/L NaCl solution, laser direct deposited amorphous composites exhibited distinctly improved corrosion resistance, compared with fully-crystallized samples.

Microstructure-Property Correlation in Magnesium-based Hydrogen Storage Systems: The Case for Ball-milled Magnesium Hydride Powder and Magnesium-based Multilayered Composites

NASA Astrophysics Data System (ADS)

Danaie, Mohsen

The main focus of this thesis is the characterization of defects and microstructure in high-energy ball milled magnesium hydride powder and magnesium-based multilayered composites. Enhancement in kinetics of hydrogen cycling in magnesium can be achieved by applying severe plastic deformation. A literature survey reveals that, due to extreme instability of alpha-MgH 2 in transmission electron microscope (TEM), the physical parameters that researchers have studied are limited to particle size and grain size. By utilizing a cryogenic TEM sample holder, we extended the stability time of the hydride phase during TEM characterization. Milling for only 30 minutes resulted in a significant enhancement in desorption kinetics. A subsequent annealing cycle under pressurized hydrogen reverted the kinetics to its initial sluggish state. Cryo-TEM analysis of the milled hydride revealed that mechanical milling induces deformation twinning in the hydride microstructure. Milling did not alter the thermodynamics of desorption. Twins can enhance the kinetics by acting as preferential locations for the heterogeneous nucleation of metallic magnesium. We also looked at the phase transformation characteristics of desorption in MgH2. By using energy-filtered TEM, we investigated the morphology of the phases in a partially desorbed state. Our observations prove that desorption phase transformation in MgH2 is of "nucleation and growth" type, with a substantial energy barrier for nucleation. This is contrary to the generally assumed "core-shell" structure in most of the simulation models for this system. We also tested the hydrogen storage cycling behavior of bulk centimeter-scale Mg-Ti and Mg-SS multilayer composites synthesized by accumulative roll-bonding. Addition of either phase (Ti or SS) allows the reversible hydrogen sorption at 350°C, whereas identically roll-bonded pure magnesium cannot be absorbed. In the composites the first cycle of absorption (also called "activation") kinetics improve with increased number of fold and roll (FR) operations. With increasing FR operations the distribution of the Ti phase is progressively refined, and the shape of the absorption curve no longer remains sigmoidal. Up to a point, increasing the loading amount of the second phase also accelerates the kinetics. Microscopy analysis performed on 1--2 wt.% hydrogen absorbed composites demonstrates that MgH 2 formed exclusively on various heterogeneous nucleation sites. During activation, MgH2 nucleation occurred at the Mg-hard phase interfaces. On the subsequent absorption cycles, heterogeneous nucleation primarily occurred in the vicinity of "internal" free surfaces such as cracks.

Nanoscale mapping of heterogeneity of the polarization reversal in lead-free relaxor–ferroelectric ceramic composites

DOE PAGES

Gobeljic, D.; Shvartsman, V. V.; Belianinov, A.; ...

2016-01-05

Relaxor/ferroelectric ceramic/ceramic composites have shown to be promising in generating large electromechanical strain at moderate electric fields. However, the mechanisms of polarization and strain coupling between grains of different nature in the composites remain unclear. To rationalize the coupling mechanisms we performed advanced piezoresponse force microscopy (PFM) studies of 0.92BNT-0.06BT-0.02KNN/0.93BNT-0.07BT (ergodic/non-ergodic relaxor) composites. PFM is able to distinguish grains of different phases by characteristic domain patterns. Polarization switching has been probed locally, on a sub-grain scale. k-Means clustering analysis applied to arrays of local hysteresis loops reveals variations of polarization switching characteristics between the ergodic and non-ergodic relaxor grains. Here,more » we report a different set of switching parameters for grains in the composites as opposed to the pure phase samples. These results confirm ceramic/ceramic composites to be a viable approach to tailor the piezoelectric properties and optimize the macroscopic electromechanical characteristics.« less

Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings

NASA Astrophysics Data System (ADS)

Francillon, Wesley

This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently used thermal barrier material of yttria stabilized zirconia (YSZ) deposited by the plasma spray processes. The rapid quenching associated with the plasma spray process, results in a metastable structure that is a non-transformable tetragonal structure in the yttria partially stabilized zirconia system rather than the equilibrium anticipated two phase mixture of cubic and monoclinic phases. It has been shown that this metastable structure offers enhanced toughness and thus durability during thermomechanical cycling from the operating temperatures in excess of 1000C to ambient. However, the metastable oxides are susceptible to partitioning at temperatures greater than 1200C, thus resulting in a transformation of the tetragonal phase oxides. Transformations of the tetragonal prime phase into the parent cubic and tetragonal prime phase result in coating degradation. Several of the emerging oxides are based on rare earth additions to zirconia. However, there is limited information of the high temperature stability of these oxide coatings and more notably these compositions exhibit limited toughness for durable performance. A potential ternary composition based on the YSZ system that offers the ability to tailor the phase structure is based YO1.5-TiO2 -ZrO2. The ternary of YO1.5-TiO2-ZrO 2 has the current TBC composition of seven molar percent yttria stabilized zirconia, pyrochlore phase oxide and zirconia doped with yttria and titania additions (Ti-YSZ). The Ti-YSZ phase field is of interest because at equilibrium it is a single tetragonal phase. Thus, compositions are of single phase tetragonal phase, theoretically, should not undergo high temperature partitioning. Single Tetragonal phase oxides of Ti-YSZ also offer the possibility of enhanced toughness and higher temperature stability akin to those observed in yttria partially stabilized zirconia. Many pyrochlore oxides are under review because they have shown to have lower thermal conductivity than YSZ oxides. This study focused on chemically synthesizing homogeneous starting material compositions in a metastable state (preferably amorphous), following its evolution according to the phase hierarchy under conditions of kinetic constraints. The current equilibrium diagram of YO1.5-TiO2-ZrO 2 is based on theoretical calculations. One of the contributions of this work is the redefined phase fields in YO1.5-TiO2-ZrO 2 based on our experimental results. Investigated compositions were based on tie lines of Y2-xTi2ZrxO7+x/2 and Y2Ti2-yZryO7 representing substitution of Zr4+ for Y3+ and Zr4+ for Ti4+ respectively. More notably, we observed extended metastable phases in pyrochlore and fluorite oxides at low temperature. The significance of this result is that it offers a larger compositional range for investing pyrochlore oxides with associated high temperature phase stability for TBC applications. In tetragonal oxides, our results showed that Ti-YSZ results have slower partitioning kinetics in comparison to YSZ at high temperature. This study also emphasized the deposition of advanced ceramic coatings by plasma spray for tetragonal and pyrochlore systems, compositionally complex functional oxides that may potentially have lower thermal conductivity values compared to current YSZ oxides. Next generation thermal barrier coatings require powders with high chemical purity, chemical homogeneity, controlled particle size/shape and pertinent phase state. Thermal spray offers an avenue to create novel materials and deposits directly from the precursor and compositionally controlled powder feedstock. This study contributed to investigating an unexplored field that offers a variety of opportunities in materials synthesis that would not be possible by conventional methods. Understanding processing-microstructure-property correlations is of considerable importance in thermal spray of functional oxide materials. This thesis demonstrated by radio-frequency thermal spray that the complex pyrochlore oxide Y 2Ti2O7 could be deposited by directly injecting molecularly mixed precursors to form oxide coatings. Structural analysis revealed the metastable fluorite phase; however, with thermal treatments at relatively low temperature of 700°C the pyrochlore phase was obtained. For Ti-YSZ coatings, the tetragonal phase oxides were obtained with unique microstructures, however, the tetragonal prime destabilized at 1200°C. This dissertation explored novel oxide compositions through detailed structural analysis. The approach presented a comprehensive and integrated investigation as it pertains to phase evolution of oxides in powder feedstock to coating characteristics (phase/properties).

Verification and Validation Process for Progressive Damage and Failure Analysis Methods in the NASA Advanced Composites Consortium

NASA Technical Reports Server (NTRS)

Wanthal, Steven; Schaefer, Joseph; Justusson, Brian; Hyder, Imran; Engelstad, Stephen; Rose, Cheryl

2017-01-01

The Advanced Composites Consortium is a US Government/Industry partnership supporting technologies to enable timeline and cost reduction in the development of certified composite aerospace structures. A key component of the consortium's approach is the development and validation of improved progressive damage and failure analysis methods for composite structures. These methods will enable increased use of simulations in design trade studies and detailed design development, and thereby enable more targeted physical test programs to validate designs. To accomplish this goal with confidence, a rigorous verification and validation process was developed. The process was used to evaluate analysis methods and associated implementation requirements to ensure calculation accuracy and to gage predictability for composite failure modes of interest. This paper introduces the verification and validation process developed by the consortium during the Phase I effort of the Advanced Composites Project. Specific structural failure modes of interest are first identified, and a subset of standard composite test articles are proposed to interrogate a progressive damage analysis method's ability to predict each failure mode of interest. Test articles are designed to capture the underlying composite material constitutive response as well as the interaction of failure modes representing typical failure patterns observed in aerospace structures.

Micromechanics, Fracture Mechanics and Gas Permeability of Composite Laminates for Cryogenic Storage Systems

NASA Technical Reports Server (NTRS)

Choi, Sukjoo; Sankar, Bhavani; Ebaugh, Newton C.

2005-01-01

A micromechanics method is developed to investigate microcrack propagation in a liquid hydrogen composite tank at cryogenic temperature. The unit cell is modeled using square and hexagonal shapes depends on fiber and matrix layout from microscopic images of composite laminates. Periodic boundary conditions are applied to the unit cell. The temperature dependent properties are taken into account in the analysis. The laminate properties estimated by the micromechanics method are compared with empirical solutions using constituent properties. The micro stresses in the fiber and matrix phases based on boundary conditions in laminate level are calculated to predict the formation of microcracks in the matrix. The method is applied to an actual liquid hydrogen storage system. The analysis predicts micro stresses in the matrix phase are large enough to cause microcracks in the composite. Stress singularity of a transverse crack normal to a ply-interface is investigated to predict the fracture behavior at cryogenic conditions using analytical and finite element analysis. When a transverse crack touches a ply-interface of a composite layer with same fiber orientation, the stress singularity is equal to 1/2. When the transverse crack propagates to a stiffer layer normal to the ply-direction, the singularity becomes less than 1/2 and vice versa. Finite element analysis is performed to predict the fracture toughness of a laminated beam subjected to fracture loads measured by four-point bending tests at room and cryogenic temperatures. As results, the fracture load at cryogenic temperature is significantly lower than that at room temperature. However, when thermal stresses are taken into consideration, for both cases of room and cryogenic temperatures, the difference of the fracture toughness becomes insignificant. The result indicates fracture toughness is a characteristic property, which is independent to temperature changes. The experimental analysis is performed to investigate the effect of cryogenic cycling on permeability for various composite material systems. Textile composites have lower permeability than laminated composites even with increasing number of cryogenic cycle. Nano-particles dispersed in laminated composites do not show improvement on permeability. The optical inspection is performed to investigate the microcrack propagation and void content in laminated composites and compared the microscopic results before and after cryogenic cycling.

Composite electrolyte with proton conductivity for low-temperature solid oxide fuel cell

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

Raza, Rizwan, E-mail: razahussaini786@gmail.com; Department of Energy Technology, Royal Institute of Technology, KTH, Stockholm 10044; Ahmed, Akhlaq

In the present work, cost-effective nanocomposite electrolyte (Ba-SDC) oxide is developed for efficient low-temperature solid oxide fuel cells (LTSOFCs). Analysis has shown that dual phase conduction of O{sup −2} (oxygen ions) and H{sup +} (protons) plays a significant role in the development of advanced LTSOFCs. Comparatively high proton ion conductivity (0.19 s/cm) for LTSOFCs was achieved at low temperature (460 °C). In this article, the ionic conduction behaviour of LTSOFCs is explained by carrying out electrochemical impedance spectroscopy measurements. Further, the phase and structure analysis are investigated by X-ray diffraction and scanning electron microscopy techniques. Finally, we achieved an ionic transport numbermore » of the composite electrolyte for LTSOFCs as high as 0.95 and energy and power density of 90% and 550 mW/cm{sup 2}, respectively, after sintering the composite electrolyte at 800 °C for 4 h, which is promising. Our current effort toward the development of an efficient, green, low-temperature solid oxide fuel cell with the incorporation of high proton conductivity composite electrolyte may open frontiers in the fields of energy and fuel cell technology.« less

High friction on ice provided by elastomeric fiber composites with textured surfaces

NASA Astrophysics Data System (ADS)

Rizvi, R.; Naguib, H.; Fernie, G.; Dutta, T.

2015-03-01

Two main applications requiring high friction on ice are automobile tires and footwear. The main motivation behind the use of soft rubbers in these applications is the relatively high friction force generated between a smooth rubber contacting smooth ice. Unfortunately, the friction force between rubber and ice is very low at temperatures near the melting point of ice and as a result we still experience automobile accidents and pedestrian slips and falls in the winter. Here, we report on a class of compliant fiber-composite materials with textured surfaces that provide outstanding coefficients of friction on wet ice. The fibrous composites consist of a hard glass-fiber phase reinforcing a compliant thermoplastic polyurethane matrix. The glass-fiber phase is textured such that it is aligned transversally and protruding out of the elastomer surface. Our analysis indicates that the exposed fiber phase exhibits a "micro-cleat" effect, allowing for it to fracture the ice and increase the interfacial contact area thereby requiring a high force to shear the interface.

The Microstructure Analysis of Barium M- Hexaferrite Particles Coated by Pani Conducting Material with In Situ Polymerization Process

NASA Astrophysics Data System (ADS)

Zainuri, M.; Amalia, L.

2017-05-01

Barium M-Hexaferrite (BaM) was synthesized by coprecipitation method and doped with Zn. Polyaniline (PANI) was synthesized by chemically and doped DBSA. The composite of PANI/BaM was synthesized by in situ polymerization method. The phase identification of the sample was performed by XRD, FTIR and SEM. Based on XRD data, the phase composition of BaM and hematite are 85.52 % and 14.48%. The characteristic peaks of PANI occur at 3435, 1637, 1473, 1298, 1127, 1009, and 799 cm-1. The characteristic metal oxide stretching peaks of BaM occurs at 575 and 437 cm-1. There is no phase changing in PANI/BaM composite. Based on SEM photography, the shape of BaM is hexagonal. The particle size of BaM powder ranges from 400-700 nm. The qualitative interfacial bonding between PANI and BaM particles are conducted very well and the both materials have good wettability.

Evaluation of calcination temperature and phase composition ratio for new hyroxyapatite

NASA Astrophysics Data System (ADS)

Salimi, M. N. Ahmad; Chin, H. S.

2017-10-01

The demand of production of hydroxyapatite (HA) has been increasing for the purpose of medical and dental application. HA possesses the excellent properties leads to the priority choice for ceramic bone replacement. Synthesis route by wet chemical precipitation is commonly practised in industrial scale. Calcium hydroxide and Orthophosphoric acid are the precursors for production scale. The synthesis of HA is conducted by varying the synthetic condition: stirring rate, calcium-phosphate and calcination temperature. This paper is focused on the properties of HA produced by regulating the synthetic condition so that the qualities of HA can be well performed. Characterization studies were also carried out by Fourier Transform Infrared Spectroscopy (FT-IR) for functional group identification, Scanning Electron Microscope (SEM) for surface morphology analysis and X-Ray Diffraction (XRD) for phase composition and crystallinity respectively. Narrow particle size distribution contributed to better quality of hydroxyapatite for bone replacement. Both calcium-phosphate ratio and calcination temperature would affect the phase composition of calcium phosphate.

A physicochemical research of the Dy-Sn-O system

NASA Astrophysics Data System (ADS)

Malinovskaya, Tatyana; Lysak, Ilya; Zhek, Valentina; Kuznetsova, Svetlana

2017-11-01

A physicochemical research of the processes of phase composition formation in the materials of the Dy-Sn-O system was performed. Phase composition was taking place in the course of thermal treatment of dysprosium (III) and tin (IV) codeposition products. These were codeposited from nitrate solutions at pH 7, and 25% ammonia water was used as the precipitant. Using thermal and X-ray diffraction analysis, it was found that in the above system at 90 wt. % of Dy2O3 and 10 wt. % of SnO2, when the precursors were heated above 600°C there are no solid solutions. In the meanwhile, at temperatures below 1000°C there is only one phase, Dy2O3. At temperatures above 1000°C, the system becomes bi-phase and includes Dy2O3 and Dy2Sn2O7.

Gas- and Particle-phase Chemical Composition Measurements Onboard the G1 Research Aircraft during the CARES Campaign

NASA Astrophysics Data System (ADS)

Shilling, J. E.; Alexander, L.; Jayne, J.; Fortner, E.

2010-12-01

An Aerodyne High Resolution Aerosol Mass Spectrometer (AMS) and an Ionicon Proton Transfer Reaction Mass Spectrometer (PTRMS) were deployed on the G1 research aircraft during the CARES campaign in Sacramento, CA to investigate aerosol gas- and particle-phase chemical composition. Preliminary analysis of PTRMS data suggests that biogenic volatile organic compounds (VOCs), particularly isoprene, dominate the region with anthropogenic VOCs, such as benzene and toluene, providing much smaller contributions to the VOC pool. Data from the AMS shows that the particle phase is dominated by organic material with smaller concentrations of ammonium sulfate and ammonium nitrate observed. Organic particle mass concentration strongly correlated with isoprene and gas-phase isoprene oxidation products, suggesting isoprene chemistry is largely controlling the organic aerosol loading in the area. The chemical evolution of the plume as it traveled downwind from Sacramento and into the foothills will also be discussed.

Fabrication and thermal properties of tetradecanol/graphene aerogel form-stable composite phase change materials.

PubMed

Mu, Boyuan; Li, Min

2018-06-11

In this study, tetradecanol/graphene aerogel form-stable composite phase change materials were prepared by physical absorption. Two kinds of graphene aerogels were prepared using vitamin C and ethylenediamine to enhance the thermal conductivity of tetradecanol and prevent its leakage during phase transition. The form-stable composite phase change material exhibited excellent thermal energy storage capacity. The latent heat of the tetradecanol/graphene aerogel composite phase change materials with 5 wt.% graphene aerogel was similar to the theoretical latent heat of pure tetradecanol. The thermal conductivity of the tetradecanol/graphene aerogel composite phase change material improved gradually as the graphene aerogel content increased. The prepared tetradecanol/graphene aerogel composite phase change materials exhibited good thermal reliability and thermal stability, and no chemical reaction occurred between tetradecanol and the graphene aerogel. In addition, the latent heat and thermal conductivity of the tetradecanol/ethylenediamine-graphene aerogel composites were higher than those of tetradecanol/vitamin C-graphene aerogel composites, and the flexible shape of the ethylenediamine-graphene aerogel is suitable for application of the tetradecanol/ethylenediamine-graphene aerogel composite.

The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites

PubMed Central

Chen, Hongda; Wang, Jihui; Ding, Anxin; Han, Xia; Sun, Ziheng

2018-01-01

In order to improve the efficiency of intumescent flame retardants (IFRs), a novel macromolecular charring agent named poly(ethanediamine-1,3,5-triazine-p-4-amino-2,2,6,6-tetramethylpiperidine) (PETAT) with gas phase and condense phase synergistic flame-retardant capability was synthesized and subsequently dispersed into polypropylene (PP) in combination with ammonium polyphosphate (APP) via a melt blending method. The chemical structure of PETAT was investigated by Fourier transform infrared spectroscopy (FTIR), and 1H nuclear magnetic resonance (NMR) spectroscopy. Thermal properties of the PETAT and IFR systems were tested by thermogravimetric-derivative thermogravimetric analysis (TGA-DTG) and thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR). The mechanical properties, thermal stability, flame-retardant properties, water resistance, and structures of char residue in flame-retardant composites were characterized using tensile and flexural strength property tests, TGA, limiting oxygen index (LOI) values before and after soaking, underwritten laboratory-94 (UL-94) vertical burning test, cone calorimetric test (CCT), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDXS), and FTIR. The results indicated that PETAT was successfully synthesized, and when the ratio of APP to PETAT was 2:1 with 25 wt % loading, the novel IFR system could reduce the deterioration of tensile strength and enhance the flexural strength of composites. Meanwhile, the flame-retardant composite was able to pass the UL-94 V-0 rating with an LOI value of 30.3%, and the peak of heat release rate (PHRR), total heat release (THR), and material fire hazard values were considerably decreased compared with others. In addition, composites also exhibited excellent water resistance properties compared with traditional IFR composites. SEM-EDXS and FTIR analyses of the char residues, as well as TG-FTIR analyses of IFR were used to investigate the flame-retardant mechanism of the APP/PETAT IFR system. The results indicated that the efficient flame retardancy of PP/IFR composites could be attributed to the synergism of the free radical-quenching and char layer-protecting mechanisms in the gas phase and condense phase, respectively. PMID:29324716

The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites.

PubMed

Chen, Hongda; Wang, Jihui; Ni, Aiqing; Ding, Anxin; Han, Xia; Sun, Ziheng

2018-01-11

In order to improve the efficiency of intumescent flame retardants (IFRs), a novel macromolecular charring agent named poly(ethanediamine-1,3,5-triazine-p-4-amino-2,2,6,6-tetramethylpiperidine) (PETAT) with gas phase and condense phase synergistic flame-retardant capability was synthesized and subsequently dispersed into polypropylene (PP) in combination with ammonium polyphosphate (APP) via a melt blending method. The chemical structure of PETAT was investigated by Fourier transform infrared spectroscopy (FTIR), and ¹H nuclear magnetic resonance (NMR) spectroscopy. Thermal properties of the PETAT and IFR systems were tested by thermogravimetric-derivative thermogravimetric analysis (TGA-DTG) and thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The mechanical properties, thermal stability, flame-retardant properties, water resistance, and structures of char residue in flame-retardant composites were characterized using tensile and flexural strength property tests, TGA, limiting oxygen index (LOI) values before and after soaking, underwritten laboratory-94 (UL-94) vertical burning test, cone calorimetric test (CCT), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDXS), and FTIR. The results indicated that PETAT was successfully synthesized, and when the ratio of APP to PETAT was 2:1 with 25 wt % loading, the novel IFR system could reduce the deterioration of tensile strength and enhance the flexural strength of composites. Meanwhile, the flame-retardant composite was able to pass the UL-94 V-0 rating with an LOI value of 30.3%, and the peak of heat release rate (PHRR), total heat release (THR), and material fire hazard values were considerably decreased compared with others. In addition, composites also exhibited excellent water resistance properties compared with traditional IFR composites. SEM-EDXS and FTIR analyses of the char residues, as well as TG-FTIR analyses of IFR were used to investigate the flame-retardant mechanism of the APP/PETAT IFR system. The results indicated that the efficient flame retardancy of PP/IFR composites could be attributed to the synergism of the free radical-quenching and char layer-protecting mechanisms in the gas phase and condense phase, respectively.

Co-axial Electrospun Polyacrylonitrile-Poly(methylmethacrylate) Nanofibers: Atomic Force Microscopy and Compositional Characterization

PubMed Central

Zander, N.E.; Strawhecker, K.E.; Orlicki, J.A.; Rawlett, A.M.; Beebe, T.P.

2011-01-01

Poly(methylmethacrylate) (PMMA)- Polyacrylonitrile (PAN) fibers were prepared using a conventional single-nozzle electrospinning technique. The as-spun fibers exhibited core-shell morphology as verified by transmission electron microscopy (TEM) and atomic force microscopy (AFM). AFM-phase and modulus mapping images of the fiber cross-section and x-ray photoelectron spectroscopy (XPS) analysis indicated PAN formed the shell and PMMA the core material. XPS, thermal gravimetric analysis (TGA), and elemental analysis were used to determine fiber compositional information. Soaking the fibers in solvent demonstrated removal of the core material, generating hollow PAN fibers. PMID:21928836

Advances in silver ion chromatography for the analysis of fatty acids and triacylglycerols-2001 to 2011.

PubMed

Momchilova, Svetlana M; Nikolova-Damyanova, Boryana M

2012-01-01

An effort is made to critically present the achievements in silver ion chromatography during the last decade. Novelties in columns, mobile-phase compositions and detectors are described. Recent applications of silver ion chromatography in the analysis of fatty acids and triacylglycerols are presented while stressing novel analytical strategies or new objects. The tendencies in the application of the method in complementary ways with reversed-phase chromatography, chiral chromatography and, especially, mass detection are outlined.

A method for the quantitative determination of crystalline phases by X-ray

NASA Technical Reports Server (NTRS)

Petzenhauser, I.; Jaeger, P.

1988-01-01

A mineral analysis method is described for rapid quantitative determination of crystalline substances in those cases in which the sample is present in pure form or in a mixture of known composition. With this method there is no need for prior chemical analysis.

Tracing the Origin of Non-ferrous Oxides in Lamination Defects on Hot-Rolled Coils: Mold Slag Entrainment vs Submerged Entry Nozzle Reaction Products

NASA Astrophysics Data System (ADS)

Sengo, Sabri; Romano Triguero, Patricia; Zinngrebe, Enno; Mensonides, Fokko

2017-06-01

In this work, lamination defects (slivers) on hot-rolled coils of Ca-treated steel were investigated for microstructure and composition using optical and scanning electron microscopy combined with microanalysis (SEM/EDS). The goal was to identify possible origins for the observed defects which contain a complex assemblage of phases, such as different types of calcium aluminates (CA, CA2, CA6), melilite (C2AS), spinel (MA), and a newly identified phase, CNA2. Mold slag similar to that employed during the cast was absent. Analysis of the bulk composition of some of the defects indicated these to be too rich in alumina to be derived from mold slag through steel-slag redox exchange. In contrast, microstructural observation of the inner side of the submerged entry nozzles (SEN) used during casting showed deposits with compositions comparable to those of the defect material. Based on an estimation of the chemical evolution of mold slag interacting with steel, it is found that the defects are not likely to be entrained mold slag but remobilized SEN deposits, as supported by several microstructural and trace phase criteria. However, it should be noted that extensive reduction of mold slag by steel can lead to compositions rich in sodic-calcic aluminates (CNA2). Therefore, differentiation between specific locations of the defect materials within a casting system requires detailed analysis from the potential sources of origin as well as from the materials found in the defects.

The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

NASA Astrophysics Data System (ADS)

Mulyawan, A.; Adi, W. A.; Mustofa, S.; Fisli, A.

2017-03-01

Unlike other AFe2O4 ferrite materials, Barium Monoferrite (BaFe2O4) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba(1-x)Sr(x)Fe2O4 has successfully been synthesized through solid state reaction method which includes BaCO3, SrCO3, and Fe2O3 as starting materials. Ba(1-x)Sr(x)Fe2O4 was made by varying the dopant composition of Strontium (Sr2+) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe2O4 was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe4O8 begin to form due to the overload expansion of the Sr2+ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe4O8 was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe2O4 and BaSrFe4O8 phase.

Process-Parameter-Dependent Optical and Structural Properties of ZrO2MgO Mixed-Composite Films Evaporated from the solid Solution

NASA Technical Reports Server (NTRS)

Sahoo, N. K.; Shapiro, A. P.

1998-01-01

The process-parameter-dependent optical and structural properties of ZrO2MgO mixed-composite material have been investigated. Optical properties were derived from spectrophotometric measurements. By use of atomic force microscopy, x-ray diffraction analysis, and energy-dispersive x-ray (EDX) analysis, the surface morphology, grain size distributions, crystallographic phases, and process-dependent material composition of films have been investigated. EDX analysis made evident the correlation between the oxygen enrichment in the films prepared at a high level of oxygen pressure and the very low refractive index. Since oxygen pressure can be dynamically varied during a deposition process, coatings constructed of suitable mixed-composite thin films can benefit from continuous modulation of the index of refraction. A step modulation approach is used to develop various multilayer-equivalent thin-film devices.

Bioimpedance analysis and HIV-related fatigue.

PubMed

Meynell, Janet; Barroso, Julie

2005-01-01

Although various physiological and psychological causes of fatigue in HIV-positive persons have been proposed, it is still not well understood. Bioimpedance analysis has proved to be an easily used, non-invasive measurement of body composition and cellular integrity. This study, looking at whether body composition as measured by bioimpedance analysis is associated with fatigue, is part of a pilot study looking for physiological and psychological biomarkers that could be factors in the fatigue experienced by HIV-positive people. Twenty-nine men and eleven women were measured for height, weight, and bioimpedance analysis. Correlations were examined between fatigue intensity and weight, body mass index, body cell mass, fat-free mass, extracellular mass, and phase angle. Because of the fat redistribution that has occurred with some people taking protease inhibitors, we also examined differences in weight, body mass index, body cell mass, fat-free mass, and fatigue intensity between those taking and those not taking protease inhibitors. There was no association between fatigue intensity and weight, body mass index, body cell mass, fat-free mass, or phase angle, nor were there differences between those taking and those not taking protease inhibitors. However, it was noted that both the phase angle and the ratio of extracellular mass to body cell mass (extracellular mass:body cell mass) were below their respective normal ranges, indicating that the participants were somewhat compromised nutritionally and with regard to cell membrane integrity. Although fatigue was not shown to be related to body composition measurement in this study, further work is needed on the causes of fatigue, because its effects on the lives of HIV-positive people can be devastating.

Depth resolved compositional analysis of aluminium oxide thin film using non-destructive soft x-ray reflectivity technique

NASA Astrophysics Data System (ADS)

Sinha, Mangalika; Modi, Mohammed H.

2017-10-01

In-depth compositional analysis of 240 Å thick aluminium oxide thin film has been carried out using soft x-ray reflectivity (SXR) and x-ray photoelectron spectroscopy technique (XPS). The compositional details of the film is estimated by modelling the optical index profile obtained from the SXR measurements over 60-200 Å wavelength region. The SXR measurements are carried out at Indus-1 reflectivity beamline. The method suggests that the principal film region is comprised of Al2O3 and AlOx (x = 1.6) phases whereas the interface region comprised of SiO2 and AlOx (x = 1.6) mixture. The soft x-ray reflectivity technique combined with XPS measurements explains the compositional details of principal layer. Since the interface region cannot be analyzed with the XPS technique in a non-destructive manner in such a case the SXR technique is a powerful tool for nondestructive compositional analysis of interface region.

Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

NASA Astrophysics Data System (ADS)

Mashovets, N. S.; Pastukh, I. M.; Voloshko, S. M.

2017-01-01

X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples' argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm2. The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. In addition, changing the technological mode allows you to manage a wide range of modified phase composition of the surface layer and as a result - to form the surface of titanium parts, taking into account the conditions of the subsequent operation.

Glass transition and composite formation in InF{sub 3}-containing oxyfluoroniobate system

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

Savchenko, N. N.; Ignatieva, L. N.; Marchenko, Yu. V.

2016-05-18

The glasses in the system MnNbOF{sub 5}-BaF{sub 2}-InF{sub 3} have been firstly synthesized and studied. The thermal parameters of these glasses are analyzed. It was stated that glass of the composition 40MnNbOF{sub 5}-40BaF{sub 2}-20InF{sub 3} is the most thermal stable in the system under study. By X-ray analysis the compositions of the crystalline phases obtained at the glass thermal treatment were determined: the main phases are Ba{sub 3}In{sub 2}F{sub 12} and BaNbOF{sub 5}. By Raman and IR spectra analysis it was stated that the networks of glasses in the system are built by the structural type of the glasses inmore » NbO{sub 2}F-BaF{sub 2} system: (NbO{sub n}F{sub m}) polyhedra joined oxygen bridges. Indium trifluoride forms InF{sub 6} polyhedra, which are embeded between oxyfluoroniobate ions, forming a common networks or forms its own layers from InF{sub 6} polyhedra. IR-spectroscopy method showed that at devitrification of the sample 30MnNbOF{sub 5}-50BaF{sub 2}-20InF{sub 3} the band position and shape change in going from glass state to crystalline. The bands in the range 900–700 cm{sup −1} shift into the low-frequency range and transformed into narrow peaks characteristic for the crystalline state. It was determined that for this sample the IR-spectroscopy method fixes the presence of the crystalline phases at 340°C without time of exposure, despite the fact that X-ray analysis shows an amorphous state for this sample at the same temperature. It was suggested, that controlling the composition and conditions of annealing of the glasses it can be obtain the transparent glass-ceramics of definite composition.« less

Evaluation of the phase properties of hydrating cement composite using simulated nanoindentation technique

NASA Astrophysics Data System (ADS)

Gautham, S.; Sindu, B. S.; Sasmal, Saptarshi

2017-10-01

Properties and distribution of the products formed during the hydration of cementitious composite at the microlevel are investigated using a nanoindentation technique. First, numerical nanoindentation using nonlinear contact mechanics is carried out on three different phase compositions of cement paste, viz. mono-phase Tri-calcium Silicate (C3S), Di-calcium Silicate (C2S) and Calcium-Silicate-Hydrate (CSH) individually), bi-phase (C3S-CSH, C2S-CSH) and multi-phase (more than 10 individual phases including water pores). To reflect the multi-phase characteristics of hydrating cement composite, a discretized multi-phase microstructural model of cement composite during the progression of hydration is developed. Further, a grid indentation technique for simulated nanoindentation is established, and employed to evaluate the mechanical characteristics of the hydrated multi-phase cement paste. The properties obtained from the numerical studies are compared with those obtained from experimental grid nanoindentation. The influence of composition and distribution of individual phase properties on the properties obtained from indentation are closely investigated. The study paves the way to establishing the procedure for simulated grid nanoindentation to evaluate the mechanical properties of heterogeneous composites, and facilitates the design of experimental nanoindentation.

Physical characteristics and magnetic properties of BaFe{sub 12}O{sub 19}/SrTiO{sub 3} based composites derived from mechanical alloying

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

Widodo, Rahmat Doni, E-mail: rahmat-doni@yahoo.com; Manaf, Azwar

2016-04-19

A composite system BaFe{sub 12}O{sub 19}/SrTiO{sub 3} with ferrimagnetic BaFe{sub 12}O{sub 19} phase (BHF) and ferroelectric SrTiO{sub 3} phase (STO) have been prepared by mechanical alloying and subsequent heat treatment. The composite powders were studied by Particle Size Analyze, X-ray diffraction and magnetic measurement. It was found that the particle size of composite powders initially increased due to laminated layers formation of a composite and then decreased to an asymptotic value of ∼8 µm as the milling time extended even to a relatively longer time. However, based on results of line broadening analysis the mean grain size of the particles wasmore » found in the nanometer scale. We thus believed that mechanical blending and milling of mixture components for the composite materials has promoted heterogeneous nucleation and only after successive sintering at 1100°C the milled powder transformed into particles of nanograin. In this report, microstructure as well as magnetic properties for the composite is also briefly discussed.« less

Application of a cholesterol stationary phase in the analysis of phosphorothioate oligonucleotides by means of ion pair chromatography coupled with tandem mass spectrometry.

PubMed

Studzińska, Sylwia; Krzemińska, Katarzyna; Szumski, Michał; Buszewski, Bogusław

2016-07-01

The main aim of this study was the investigation of the influence of several ion pair reagents towards both the retention and the mass spectrometry sensitivity of phosphorothioate oligonucleotides. A cholesterol stationary phase was applied for the first time in the analysis of this group of compounds. The mobile phase composition was modified by changing the concentration and the type of amines and acetates or 1,1,1,3,3,3-hexafluoroisopropanol. It has been shown that the increase of amines concentration results in the retention factor increase for each oligonucleotide, on each adsorbent. The only exception was the mobile phase composed of triethylamine and 1,1,1,3,3,3-hexafluoroisopropanol. This is a consequence of interactions taking place between a cholesterol molecule and an alcohol. This effect was convenient when the mass spectrometry detection was applied, since it allowed an increase in the sensitivity. Moreover, optimization of the mobile phase composition and its impact on the efficiency of ionization process and on the sensitivity in mass spectrometry were also presented. The optimization of this new method, based on cholesterol stationary phase coupled with mass spectrometry detection, was finally applied for the determination of phosphorothioate oligonucleotides impurity in a real sample. Copyright © 2016 Elsevier B.V. All rights reserved.

Kinetics and pathways for crystallization of amorphous mullite and YAG

NASA Astrophysics Data System (ADS)

Johnson, Bradley Richard

The crystallization behavior of quenched mullite (3Al2O 3•2SiO2) and YAG (Y3Al5O 12) composition glasses (made using containerless methods) were characterized with the ultimate goal of producing single crystal, structural, ceramic oxide fibers from these materials. The kinetics for crystallization were determined from thermal analysis experiments. From the results, time-temperature-transformation (TTT) curves were calculated. The crystallization pathways were determined by examining the crystal structure, microstructure, and chemical composition of heat treated specimens using x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A machine was also designed and built to facilitate controlled crystallization of amorphous fibers. Quenched, Y3Al5O12 composition beads crystallized at temperatures as low as 840°C. The as-received specimens contained a few, small YAG crystals, in addition to a mixture of different amorphous phases. The coexistence of two different amorphous phases of the same composition, but having different densities is termed polyamorphism, and this has been reported to occur in Y3Al5O12 composition quenched melts. Although various crystallization pathways have been reported for chemically synthesized YAG precursors, these specimens crystallized directly into YAG, which was the only phase formed. Quenched, 3Al2O3•2SiO2 composition mullite beads and fibers crystallized at temperatures as low as 920°C. Due to phase separation in the quenched melts, multiple phases with slightly different compositions and different crystallization activation energies crystallized. These phases were not equilibrium, 3:2 mullite, but metastable, alumina-rich, pseudotetragonal mullite. The residual, amorphous, silica-rich phase existed as numerous, 7--10 nm sized inclusions embedded within pseudotetragonal mullite. A large amount of internal strain was detected in pseudotetragonal mullite, and the source of this strain was suggested to be the embedded, silica-rich inclusions. Pseudotetragonal mullite gradually converted to equilibrium, orthorhombic, 3:2 mullite between 1000--1400°C. This was characterized by assimilation of the embedded, silica-rich inclusions and the elimination of internal strain. Additionally, recrystallization of numerous, small, strain- and inclusion-free, 3:2 mullite grains was observed to occur as the process proceeded to completion.

Micromechanics and constitutive models for soft active materials with phase evolution

NASA Astrophysics Data System (ADS)

Wang, Binglian

Soft active materials, such as shape memory polymers, liquid crystal elastomers, soft tissues, gels etc., are materials that can deform largely in response to external stimuli. Micromechanics analysis of heterogeneous materials based on finite element method is a typically numerical way to study the thermal-mechanical behaviors of soft active materials with phase evolution. While the constitutive models that can precisely describe the stress and strain fields of materials in the process of phase evolution can not be found in the databases of some commercial finite element analysis (FEA) tools such as ANSYS or Abaqus, even the specific constitutive behavior for each individual phase either the new formed one or the original one has already been well-known. So developing a computationally efficient and general three dimensional (3D) thermal-mechanical constitutive model for soft active materials with phase evolution which can be implemented into FEA is eagerly demanded. This paper first solved this problem theoretically by recording the deformation history of each individual phase in the phase evolution process, and adopted the idea of effectiveness by regarding all the new formed phase as an effective phase with an effective deformation to make this theory computationally efficient. A user material subroutine (UMAT) code based on this theoretical constitutive model has been finished in this work which can be added into the material database in Abaqus or ANSYS and can be easily used for most soft active materials with phase evolution. Model validation also has been done through comparison between micromechanical FEA and experiments on a particular composite material, shape memory elastomeric composite (SMEC) which consisted of an elastomeric matrix and the crystallizable fibre. Results show that the micromechanics and the constitutive models developed in this paper for soft active materials with phase evolution are completely relied on.

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

Sun, Pei; Fang, Z. Zak; Koopman, Mark

Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in themore » (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.« less

Competing magnetic interactions and low temperature magnetic phase transitions in composite multiferroics

NASA Astrophysics Data System (ADS)

Borkar, Hitesh; Choudhary, R. J.; Singh, V. N.; Tomar, M.; Gupta, Vinay; Kumar, Ashok

2015-08-01

Novel magnetic properties and magnetic interactions in composite multiferroic oxides Pb[(Zr0.52Ti0.48)0.60(Fe0.67W0.33).40]O3]0.80-[CoFe2O4]0.20 (PZTFW-CFO) have been studied from 50 to 1000 Oe field cooled (FC) and zero field cooled (ZFC) probing conditions, and over a wide range of temperatures (4-350 K). Crystal structure analysis, surface morphology, and high resolution transmission electron microscopy images revealed the presence of two distinct phases, where micro- and nano-size spinel CFO were embedded in tetragonal PZTFW matrix and applied a significant built-in compressive strain (˜0.4-0.8%). Three distinct magnetic phase transitions were observed with the subtle effect of CFO magnetic phase on PZTFW magnetic phase transitions below the blocking temperature (TB). Temperature dependence magnetic property m(T) shows a clear evidence of spin freezing in magnetic order with lowering in thermal vibration. Chemical inhomogeneity and confinement of nanoscale ferrimagnetic phase in paramagnetic/antiferromagnetic matrix restrict the long range interaction of spin which in turn develop a giant spin frustration. A large divergence in the FC and ZFC data and broad hump in ZFC data near 200 (±10) K were observed which suggests that large magnetic anisotropy and short range order magnetic dipoles lead to the development of superparamagnetic states in composite.

Preparation of nano-TiO2/diatomite-based porous ceramics and their photocatalytic kinetics for formaldehyde degradation

NASA Astrophysics Data System (ADS)

Gao, Ru-qin; Sun, Qian; Fang, Zhi; Li, Guo-ting; Jia, Meng-zhe; Hou, Xin-mei

2018-01-01

Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650°C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm-1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated under UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were κ = 0.576 mg·m-3·min-1 and K = 0.048 m3/mg.

SemanticSCo: A platform to support the semantic composition of services for gene expression analysis.

PubMed

Guardia, Gabriela D A; Ferreira Pires, Luís; da Silva, Eduardo G; de Farias, Cléver R G

2017-02-01

Gene expression studies often require the combined use of a number of analysis tools. However, manual integration of analysis tools can be cumbersome and error prone. To support a higher level of automation in the integration process, efforts have been made in the biomedical domain towards the development of semantic web services and supporting composition environments. Yet, most environments consider only the execution of simple service behaviours and requires users to focus on technical details of the composition process. We propose a novel approach to the semantic composition of gene expression analysis services that addresses the shortcomings of the existing solutions. Our approach includes an architecture designed to support the service composition process for gene expression analysis, and a flexible strategy for the (semi) automatic composition of semantic web services. Finally, we implement a supporting platform called SemanticSCo to realize the proposed composition approach and demonstrate its functionality by successfully reproducing a microarray study documented in the literature. The SemanticSCo platform provides support for the composition of RESTful web services semantically annotated using SAWSDL. Our platform also supports the definition of constraints/conditions regarding the order in which service operations should be invoked, thus enabling the definition of complex service behaviours. Our proposed solution for semantic web service composition takes into account the requirements of different stakeholders and addresses all phases of the service composition process. It also provides support for the definition of analysis workflows at a high-level of abstraction, thus enabling users to focus on biological research issues rather than on the technical details of the composition process. The SemanticSCo source code is available at https://github.com/usplssb/SemanticSCo. Copyright © 2017 Elsevier Inc. All rights reserved.

Isotopic Composition of Carbon Dioxide Released from Confidence Hills Sediment as Measured by the Sample Analysis at Mars (SAM) Quadrupole Mass Spectrometer

NASA Technical Reports Server (NTRS)

Franz, H. B.; Mahaffy, P. R.; Stern, J.; Archer, P., Jr.; Conrad, P.; Eigenbrode, J.; Freissinet, C.; Glavin, D.; Grotzinger, J. P.; Jones, J.;

Phase-field model for isothermal phase transitions in binary alloys

NASA Technical Reports Server (NTRS)

Wheeler, A. A.; Boettinger, W. J.; Mcfadden, G. B.

1992-01-01

A new phase field model is described which models isothermal phase transitions between ideal binary alloy solution phases. Equations are developed for the temporal and spatial variation of the phase field, which describes the identity of the phase, and of the composition. An asymptotic analysis, as the gradient energy coefficient of the phase field becomes small, was conducted. From the analysis, it is shown that the model recovers classical sharp interface models of this situation when the interfacial layers are thin, and they show how to relate the parameters appearing in the phase field model to material and growth parameters in real systems. Further, three stages of temporal evolution are identified: the first corresponding to interfacial genesis which occurs very rapidly; the second to interfacial motion controlled by the local energy difference across the interface and diffusion; the last taking place on a long time scale in which curvature effects are important and which correspond to Ostwald ripening. The results of the numerical calculations are presented.

Evolution of the Structural-Phase State of a Ti-Al- V-Mo Alloy During Severe Plastic Deformation and SubSequent Annealing

NASA Astrophysics Data System (ADS)

Grabovetskaya, G. P.; Ratochka, I. V.; Mishin, I. P.; Zabudchenko, O. V.; Lykova, O. N.

2016-05-01

The effect of the initial phase composition of a Ti-Al-V-Mo alloy (VT16 according to Russian classification) on the evolution of its structural-phase state during the formation of ultrafine-grained structure and subsequent annealing is investigated by methods of optical and transmission electron microscopy and x-ray diffraction analysis. The structure is produced by cyclic pressing with a change of the deformation axis in each cycle combined with a gradual decrease of the pressing temperature from 1073 to 723 K. As this takes place, α″ → α + β and β → α phase transitions are found to develop in the test alloy. The phase state of the ultrafinegrained material thus produced depends for the most part on its elemental composition and severe plastic deformation regime. Annealing below the recrystallization temperature is shown to give rise to a β→α phase transition and alloying element redistribution. The foregoing processes allow for retaining a high level of the strength properties of the alloy.

New eutectic alloys and their heats of transformation

NASA Technical Reports Server (NTRS)

Farkas, D.; Birchenall, C. E.

1985-01-01

Eutectic compositions and congruently melting intermetallic compounds in binary and multicomponent systems among common elements such as Al, Ca, Cu, Mg, P, Si, and Zn may be useful for high temperature heat storage. In this work, heats of fusion of new multicomponent eutectics and intermetallic phases are reported, some of which are competitive with molten salts in heat storage density at high temperatures. The method used to determine unknown eutectic compositions combined results of differential thermal analysis, metallography, and microprobe analysis. The method allows determination of eutectic compositions in no more than three steps. The heats of fusion of the alloys were measured using commercial calorimeters, a differential thermal analyzer, and a differential scanning calorimeter.

The effect of radiation on the thermal properties of chitosan/mimosa tenuiflora and chitosan/mimosa tenuiflora/multiwalled carbon nanotubes (MWCNT) composites for bone tissue engineering

NASA Astrophysics Data System (ADS)

Martel-Estrada, S. A.; Santos-Rodríguez, E.; Olivas-Armendáriz, I.; Cruz-Zaragoza, E.; Martínez-Pérez, C. A.

2014-07-01

The purpose of this study is to examine the effect of gamma radiation and UV radiation on the microstructure, chemical structure and thermal stability of Chitosan/Mimosa Tenuiflora and Chitosan/Mimosa Tenuiflora/MWCNT composites scaffolds produced by thermally induced phase separation. The composites were irradiated and observed to undergo radiation-induced degradation through chain scission. Morphology, thermal properties and effects on chemical and semi-crystalline structures were obtained by scanning electronic microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), FT-IR analysis and X-ray Diffraction. A relationship between radiation type and the thermal stability of the composites, were also established. This relationship allows a more accurate and precise control of the life span of Chitosan/Mimosa Tenuiflora and Chitosan/Mimosa Tenuiflora/MWCNT composites through the use of radiation in materials for use in tissue engineering.

Salt Composition Derived from Veazey Composition by Thermodynamic Modeling and Predicted Composition of Drum Contents

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

Weisbrod, Kirk Ryan; Veirs, Douglas Kirk; Funk, David John

This report describes the derivation of the salt composition from the Veazey salt stream analysis. It also provides an estimate of the proportions of the kitty litter, nitrate salt and neutralizer that was contained in drum 68660. While the actinide content of waste streams was judiciously followed in the 1980s in TA-55, no record of the salt composition could be found. Consequently, a salt waste stream produced from 1992 to 1994 and reported by Gerry Veazey provided the basis for this study. While chemical analysis of the waste stream was highly variable, an average analysis provided input to the Streammore » Analyzer software to calculate a composition for a concentrated solid nitrate salt and liquid waste stream. The calculation predicted the gas / condensed phase compositions as well as solid salt / saturated liquid compositions. The derived composition provides an estimate of the nitrate feedstream to WIPP for which kinetic measurements can be made. The ratio of salt to Swheat in drum 68660 contents was estimated through an overall mass balance on the parent and sibling drums. The RTR video provided independent confirmation concerning the volume of the mixture. The solid salt layer contains the majority of the salt at a ratio with Swheat that potentially could become exothermic.« less

Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

NASA Astrophysics Data System (ADS)

Volkova, E. F.

2017-07-01

Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg - Mn, Mg - Al, Mg - Al - Mn, and Mg - Al - Zn - Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

Fatty acid composition and its association with chemical and sensory analysis of boar taint.

PubMed

Liu, Xiaoye; Trautmann, Johanna; Wigger, Ruth; Zhou, Guanghong; Mörlein, Daniel

2017-09-15

A certain level of disagreement between the chemical analysis of androstenone and skatole and the human perception of boar taint has been found in many studies. Here we analyze whether the fatty acid composition can explain such inconsistency between sensory evaluation and chemical analysis of boar taint compounds. Therefore, back fat samples (n=143) were selected according to their sensory evaluation by a 10-person sensory panel, and the chemical analysis (stable isotope dilution analysis with headspace solid-phase microextraction and gas chromatography-mass spectrometry) of androstenone and skatole. Subsequently a quantification of fatty acids using gas chromatography-flame ionization detection was conducted. The correlation analyses revealed that several fatty acids are significantly correlated with androstenone, skatole, and the sensory rating. However, multivariate analyses (principal component analysis) revealed no explanation of the fatty acid composition with respect to the (dis-)agreement between sensory and chemical analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of superheating in the formation of Glass Mountain obsidians (Long Valley, CA) inferred through crystallization of sanidine

NASA Astrophysics Data System (ADS)

Waters, Laura E.; Andrews, Benjamin J.

2016-10-01

The Glass Mountain obsidians (Long Valley, CA) are crystal poor (<8 vol%) and highly evolved (high SiO2, low Sr), and therefore, their formation required extremely efficient separation of melts from a crystal-rich source. A petrologic and experimental investigation of the mineral phases in Glass Mountain lavas identifies conditions under which phenocrysts grew and the driving mechanism for crystallization, which places constraints on the possible processes that generated the obsidians. The obsidian in this study (GM-11) is saturated in nine phases (sanidine + quartz + plagioclase + titanomagnetite + ilmenite + zircon + apatite + allanite + biotite), and results of high-resolution SEM compositional mapping and electron microprobe analysis reveal that individual sanidine crystals are normally zoned and span a range of compositions (Or40-78). Sanidines have a "granophyric" texture, characterized by intergrowths of quartz and sanidine. Mineral phases in the natural sample are compared to H2O-saturated phase equilibrium experiments conducted in cold-seal pressure vessels, over a range of conditions (700-850 °C; 75-225 MPa), and all are found to be plausible phenocrysts. Comparison of sanidine compositions from the natural sample with those grown in phase equilibrium experiments demonstrates that sanidine in the natural sample occurs in a reduced abundance. Further comparison with phase equilibrium experiments suggests that sanidine compositions track progressive loss of dissolved melt water (±cooling), suggesting that crystallization in the natural obsidian was driven predominantly by degassing resulting from decompression. It is paradoxical that an effusively (slowly) erupted lava should contain multiple phenocryst phases, including sanidine crystals that span a range of compositions with granophyric textures, and yet remain so crystal poor. To resolve this paradox, it is necessary that the solidification mechanism (degassing or cooling) that produced the sanidine crystals (and other mineral phases) must have an associated kinetic effect(s) that efficiently hinders crystal nucleation and growth. Decompression experiments conducted in this study and from the literature collectively demonstrate that the simplest way to inhibit nucleation during degassing-induced crystallization is to initiate degassing ± cooling from superliquidus conditions, and therefore, the Glass Mountain obsidians were superheated prior to crystallization.

Molecular analysis of bacterial microbiota associated with oysters (Crassostrea gigas and Crassostrea corteziensis) in different growth phases at two cultivation sites.

PubMed

Trabal, Natalia; Mazón-Suástegui, José M; Vázquez-Juárez, Ricardo; Asencio-Valle, Felipe; Morales-Bojórquez, Enrique; Romero, Jaime

2012-08-01

Microbiota presumably plays an essential role in inhibiting pathogen colonization and in the maintenance of health in oysters, but limited data exist concerning their different growth phases and conditions. We analyzed the bacterial microbiota composition of two commercial oysters: Crassostrea gigas and Crassostrea corteziensis. Differences in microbiota were assayed in three growth phases: post-larvae at the hatchery, juvenile, and adult at two grow-out cultivation sites. Variations in the microbiota were assessed by PCR analysis of the 16S rRNA gene in DNA extracted from depurated oysters. Restriction fragment length polymorphism (RFLP) profiles were studied using Dice's similarity coefficient (Cs) and statistical principal component analysis (PCA). The microbiota composition was determined by sequencing temperature gradient gel electrophoresis (TGGE) bands. The RFLP analysis of post-larvae revealed homology in the microbiota of both oyster species (Cs > 88 %). Dice and PCA analyses of C. corteziensis but not C. gigas showed differences in the microbiota according to the cultivation sites. The sequencing analysis revealed low bacterial diversity (primarily β-Proteobacteria, Firmicutes, and Spirochaetes), with Burkholderia cepacia being the most abundant bacteria in both oyster species. This study provides the first description of the microbiota in C. corteziensis, which was shown to be influenced by cultivation site conditions. During early growth, we observed that B. cepacia colonized and remained strongly associated with the two oysters, probably in a symbiotic host-bacteria relationship. This association was maintained in the three growth phases and was not altered by environmental conditions or the management of the oysters at the grow-out site.

Brillouin Optical Correlation Domain Analysis in Composite Material Beams

PubMed Central

Stern, Yonatan; London, Yosef; Preter, Eyal; Antman, Yair; Diamandi, Hilel Hagai; Silbiger, Maayan; Adler, Gadi; Shalev, Doron; Zadok, Avi

2017-01-01

Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA) protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a) monitoring the production and curing of a composite beam over 60 h; (b) estimating the stiffness and Young’s modulus of a composite beam; and (c) distributed strain measurements across the surfaces of a model wing of an unmanned aerial vehicle. The measurements are supported by the predictions of structural analysis calculations. The results illustrate the potential added values of high-resolution, distributed Brillouin sensing in the structural health monitoring of composites. PMID:28974041

Brillouin Optical Correlation Domain Analysis in Composite Material Beams.

PubMed

Stern, Yonatan; London, Yosef; Preter, Eyal; Antman, Yair; Diamandi, Hilel Hagai; Silbiger, Maayan; Adler, Gadi; Levenberg, Eyal; Shalev, Doron; Zadok, Avi

2017-10-02

Structural health monitoring is a critical requirement in many composites. Numerous monitoring strategies rely on measurements of temperature or strain (or both), however these are often restricted to point-sensing or to the coverage of small areas. Spatially-continuous data can be obtained with optical fiber sensors. In this work, we report high-resolution distributed Brillouin sensing over standard fibers that are embedded in composite structures. A phase-coded, Brillouin optical correlation domain analysis (B-OCDA) protocol was employed, with spatial resolution of 2 cm and sensitivity of 1 °K or 20 micro-strain. A portable measurement setup was designed and assembled on the premises of a composite structures manufacturer. The setup was successfully utilized in several structural health monitoring scenarios: (a) monitoring the production and curing of a composite beam over 60 h; (b) estimating the stiffness and Young's modulus of a composite beam; and (c) distributed strain measurements across the surfaces of a model wing of an unmanned aerial vehicle. The measurements are supported by the predictions of structural analysis calculations. The results illustrate the potential added values of high-resolution, distributed Brillouin sensing in the structural health monitoring of composites.

Phase transformations in 40-60-GPa shocked gneisses from the Haughton Crater (Canada): An Analytical Transmission Electron Microscopy (ATEM) study

NASA Technical Reports Server (NTRS)

Martinez, I.; Guyot, F.; Schaerer, U.

1992-01-01

In order to better understand phase transformations, chemical migration, and isotopic disequilibrium in highly shocked rocks, we have performed a microprobe and an ATEM study on gneisses shocked up to 60 GPa from the Haughton Crater. This study reveals the following chemical and structural characteristics: (1) SiO2 dominant areas are formed by a mixture of pure SiO2 polycrystalline quartz identified by electron diffraction pattern and chemical analysis and a silica-rich amorphous phase containing minor amounts of aluminium, potassium, and iron; (2) Areas with biotitelike composition are formed by less than 200-nm grains of iron-rich spinels embedded in a silica-rich amorphous phase that is very similar to the one described above; (3) Layers with feldsparlike composition are constituted by 100-200-nm-sized alumina-rich grains (the indexation of the crystalline structure is under progress) and the silica-rich amorphous phase; (4) Zones characterized by the unusual Al/Si ratio close to 1 are formed by spinel grains (200-nm-sized) embedded in the same silica-rich amorphous phase; and (5) The fracturated sillimanites contain domains with a lamellar structure, defined by the intercalation of 100-nm-wide lamellae of mullite crystals and of a silica-rich amorphous phase. These mullite crystals preserved the crystallographical orientation of the preshock sillimanite. All compositional domains, identified at the microprobe scale, can thus be explained by a mixture in different proportion between the following phases: (1) a silica-rich amorphous phase, with minor Al and K; (2) quartz crystals; (3) spinel crystals and alumina-rich crystals; (4) sillimanite; and (5) mullite. Such mixtures of amorphous phases and crystals in different proportions explain disturbed isotope systems in these rocks and chemical heterogeneities observed on the microprobe.

Cosputtering crystal growth of zinc oxide-based composite films: From the effects of doping to phase on photoactivity and gas sensing properties

NASA Astrophysics Data System (ADS)

Liang, Yuan-Chang; Lee, Chia-Min

2016-10-01

ZnO-In2O3 (InO) composite thin films were grown by radio frequency cosputtering ZnO and InO ceramic targets in this study. The indium content of the composite films was varied from 1.7 at. % to 8.2 at. % by varying the InO sputtering power during cosputtering thin-film growth. X-ray diffraction and transmission electron microscopy analysis results show that the high indium content leads to the formation of a separated InO phase in the ZnO matrix. The surface crystallite size and roughness of the ZnO-InO composite films grown here increased with an increasing indium content. Furthermore, under the conditions of a higher indium content and InO sputtering power, the number of crystal defects in the composite films increased, and the optical absorbance edge of the composite films broadened. The photoactivity and ethanol gas sensing response of the ZnO-InO composite films increased as their indium content increased; this finding is highly correlated with the microstructural evolution of ZnO-InO composite films of various indium contents, which is achieved by varying the InO sputtering power during cosputtering.

Composite, nanostructured, super-hydrophobic material

DOEpatents

D'Urso, Brian R [Clinton, TN; Simpson, John T [Clinton, TN

2007-08-21

A hydrophobic disordered composite material having a protrusive surface feature includes a recessive phase and a protrusive phase, the recessive phase having a higher susceptibility to a preselected etchant than the protrusive phase, the composite material having an etched surface wherein the protrusive phase protrudes from the surface to form a protrusive surface feature, the protrusive feature being hydrophobic.

Parameters of Models of Structural Transformations in Alloy Steel Under Welding Thermal Cycle

NASA Astrophysics Data System (ADS)

Kurkin, A. S.; Makarov, E. L.; Kurkin, A. B.; Rubtsov, D. E.; Rubtsov, M. E.

2017-05-01

A mathematical model of structural transformations in an alloy steel under the thermal cycle of multipass welding is suggested for computer implementation. The minimum necessary set of parameters for describing the transformations under heating and cooling is determined. Ferritic-pearlitic, bainitic and martensitic transformations under cooling of a steel are considered. A method for deriving the necessary temperature and time parameters of the model from the chemical composition of the steel is described. Published data are used to derive regression models of the temperature ranges and parameters of transformation kinetics in alloy steels. It is shown that the disadvantages of the active visual methods of analysis of the final phase composition of steels are responsible for inaccuracy and mismatch of published data. The hardness of a specimen, which correlates with some other mechanical properties of the material, is chosen as the most objective and reproducible criterion of the final phase composition. The models developed are checked by a comparative analysis of computational results and experimental data on the hardness of 140 alloy steels after cooling at various rates.

Headspace solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the analysis of aerosol from tobacco heating product.

PubMed

Savareear, Benjamin; Lizak, Radoslaw; Brokl, Michał; Wright, Chris; Liu, Chuan; Focant, Jean-Francois

2017-10-20

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was developed and optimised to elucidate the volatile composition of the particulate phase fraction of aerosol produced by tobacco heating products (THPs). Three SPME fiber types were studied in terms of extraction capacity and precision measurements. Divinylbenzene polydimethylsiloxane appeared as the most efficient coating for these measurements. A central composite design of experiment was utilised for the optimization of the extraction conditions. Qualitative and semi-quantitative analysis of the headspace above THP aerosol condensate was carried out using optimised extraction conditions. Semi-quantitative analyses of detected constituents were performed by assuming that their relative response factors to the closest internal standard ( i t R ) were equal to 1. Using deconvoluted mass spectral data (library similarity and reverse match >750) and linear retention indices (match window of ±15 index units), 205 peaks were assigned to individual compounds, 82 of which (including 43 substances previously reported to be present in tobacco) have not been reported previously in tobacco aerosol. The major volatile fraction of the headspace contained ketones, alcohols, aldehydes, alicyclic hydrocarbons alkenes, and alkanes. The method was further applied to compare the volatiles from the particulate phase of aerosol composition of THP with that of reference cigarette smoke and showed that the THP produced a less complex chemical mixture. This new method showed good efficiency and precision for the peak areas and peak numbers from the volatile fraction of aerosol particulate phase for both THP and reference cigarettes. Copyright © 2017 Elsevier B.V. All rights reserved.

Advanced methods for preparation and characterization of infrared detector materials. [mercury cadmium telluride alloys

NASA Technical Reports Server (NTRS)

Lehoczky, S. L.; Szofran, F. R.

1981-01-01

Differential thermal analysis data were obtained on mercury cadmium telluride alloys in order to establish the liquidus temperatures for the various alloy compositions. Preliminary theoretical analyses was performed to establish the ternary phase equilibrium parameters for the metal rich region of the phase diagram. Liquid-solid equilibrium parameters were determined for the pseudobinary alloy system. Phase equilibrium was calculated and Hg(l-x) Cd(x) Te alloys were directionally solidified from pseudobinary melts. Electrical resistivity and Hall coefficient measurements were obtained.

Preparation and Characterization of Hydroxyapatite-Silica Composite Nanopowders

NASA Astrophysics Data System (ADS)

Latifi, S. M.; Fathi, M. H.; Golozar, M. A.

One of the most important objectives in the field of biomaterials science and engineering is development of new materials as bone substitutes. Silica (SiO2) has an important role in the biomineralization and biological responses. The aim of this research was to prepare and characterize hydroxyapatite-silica (HA-SiO2) composite nanopowder with different content of silica. Hydroxyapatite-silica composite nanopowders with 20 and 40 wt% silica were prepared using a sol-gel method at 600°C with phosphoric pentoxide and calcium nitrate tetrahydrate as a source of hydroxyapatite; also, tetraethylorthosilicate and methyltriethoxisilane as a source of silica. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques were used for characterization and evaluation of the products. The results indicated the presence of nanocrystalline hydroxyapatite phase beside amorphous silica phase in prepared composite nanopowders. Moreover, by increasing the content of silica in composite nanopowders, the crystallinity will be decreased,and the ability of the product as a bone substitute material might be controlled by changing the content of the ingredients and subsequently its structure.

Comparison of dynamic fatigue behavior between SiC whisker-reinforced composite and monolithic silicon nitrides

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Salem, Jonathan A.

1991-01-01

The dynamic fatigue behavior of 30 vol percent silicon nitride whisker-reinforced composite and monolithic silicon nitrides were determined as a function of temperature from 1100 to 1300 C in ambient air. The fatigue susceptibility parameter, n, decreased from 88.1 to 20.1 for the composite material, and from 50.8 to 40.4 for the monolithic, with increasing temperature from 1100 to 1300 C. A transition in the dynamic fatigue curve occurred for the composite material at a low stressing rate of 2 MPa/min at 1300 C, resulting in a very low value of n equals 5.8. Fractographic analysis showed that glassy phases in the slow crack growth region were more pronounced in the composite compared to the monolithic material, implying that SiC whisker addition promotes the formation of glass rich phases at the grain boundaries, thereby enhancing fatigue. These results indicate that SiC whisker addition to Si3 N4 matrix substantially deteriorates fatigue resistance inherent to the matrix base material for this selected material system.

A low bioimpedance phase angle predicts a higher mortality and lower nutritional status in chronic dialysis patients

NASA Astrophysics Data System (ADS)

Dumler Md, Francis

2010-04-01

Bioelectrical impedance analysis is an established technique for body composition analysis. The phase angle parameter, an index of body cell mass, tissue hydration, and membrane integrity, makes it suitable for assessing nutritional status and survivability. We evaluated the significance of a low phase angle value on nutritional status and mortality in 285 chronic dialysis patients during a longitudinal prospective observational study. Patients in the lower phase angle tertile had decreased body weight, body mass index, fat free mass, body cell mass, and lower serum albumin concentrations than those in the higher tertile (P<001). In addition, mortality rates were significantly lower (P=0.05) in the highest tertile patients. In conclusion, the phase angle is a useful method for identifying dialysis patients at high risk for malnutrition and increased mortality.

Grain Surface Chemistry and the Composition of Interstellar Ices

NASA Technical Reports Server (NTRS)

Tielens, A. G. G. M.

2006-01-01

Submicron sized dust grains are an important component of the interstellar medium. In particular they provide surface where active chemistry can take place. At the low temperatures (-10 K) of the interstellar medium, colliding gas phase species will stick, diffuse, react, and form an icy mantle on these dust grains. This talk will review the principles of grain surface chemistry and delineate important grain surface routes, focusing on reactions involving H, D, and O among each other and with molecules such as CO. Interstellar ice mantles can be studied through the fundamental vibrations of molecular species in the mid-infrared spectra of sources embedded in or located behind dense molecular clouds. Analysis of this type of data has provided a complex view of the composition of these ices and the processes involved. Specifically, besides grain surface chemistry, the composition of interstellar ices is also affected by thermal processing due to nearby newly formed stars. This leads to segregation between different ice components as well as outgassing. The latter results in the formation of a so-called Hot Core region with a gas phase composition dominated by evaporated mantle species. Studies of such regions provide thus a different view on the ice composition and the chemical processes involved. Interstellar ices can also be processed by FUV photons and high energy cosmic ray ions. Cosmic ray processing likely dominates the return of accreted species to the gas phase where further gas phase reactions can take place. These different chemical routes towards molecular complexity in molecular clouds and particularly regions of star formation will be discussed.

Thermal characteristic investigation of eutectic composite fatty acid as heat storage material for solar heating and cooling application

NASA Astrophysics Data System (ADS)

Thaib, R.; Fauzi, H.; Ong, H. C.; Rizal, S.; Mahlia, T. M. I.; Riza, M.

2018-03-01

A composite phase change material (CPCM) of myristic acid/palmitic acid/sodium myristate (MA/PA/SM) and of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) were impregnated with purified damar gum as called Shorea Javanica (SJ) to improve the thermal conductivity of CPCM. The thermal properties, thermal conductivity, and thermal stability of both CPCM have investigated by using a Differential Scanning Calorimetry (DSC) thermal analysis, hot disc thermal conductivity analyzer, and Simultaneous Thermal Analyzer (STA), simultaneously. However, a chemical compatibility between both fatty acid eutectic mixtures and SJ in composite mixtures measured by Fourier Transform Infra-Red (FT-IR) spectrophotometer. The results were obtained that the thermal conductivity of MA/PA/SM/SJ and MA/PA/SL/SJ eutectic composite phase change material (CPCM) were improved by addition 3 wt.% and 2 wt.% of Shorea javanica (SJ), respectively, without occur a significant change on thermal properties of CPCM. Moreover, the absorbance spectrum of FT-IR shows the good compatibility of SJ with both MA/PA/SM and MA/PA/SL eutectic mixtures, the composite PCM also present good thermal performance and good thermal stability. Therefore, it can be noted that the purified Shorea Javanica proposed, the as high conductive material in this study was able to improve the thermal conductivity of eutectic PCM without any significant reduction on its thermo-physical and chemical properties and can be recommended as novelty composite phase change material for thermal energy storage application.

Effects of Stirring and Fluid Perfusion on the In Vitro Degradation of Calcium Phosphate Cement/PLGA Composites.

PubMed

An, Jie; Leeuwenburgh, Sander C G; Wolke, Joop G C; Jansen, John A

2015-11-01

In vitro degradation rates of calcium phosphate bioceramics are investigated using a large variation of soaking protocols that do not all match the dynamic conditions of the perfused physiological environment. Therefore, we studied the effect of stirring and fluid perfusion on the in vitro degradation rate of apatitic calcium phosphate cements (CPC) containing poly(lactic-co-glycolic acid) (PLGA) microspheres. The composites were soaked in phosphate-buffered saline up to 6 weeks under unstirred, stirred, or perfused conditions followed by analysis of mass loss, compression strength, porosity, crystal phase composition, and morphology of the cement composites. The results showed that fluid perfusion reduced the decrease in pH and corresponding degradation rates, while nonperfused soaking conditions (i.e., stirred and unstirred conditions) resulted into more extensive acidification, the rate of which increased with stirring. After 2 weeks, the formation of a secondary brushite phase was observed for cement composites soaked under nonperfused (i.e., stirred and unstirred) conditions, whereas this phase was not detected in cements soaked under perfused conditions. The degradation rate of cement composites decreased in the order unstirred>stirred>perfused, as evidenced by quantification of mass loss, compression strength, and pore morphology. To summarize, we have demonstrated that soaking conditions strongly affected the in vitro degradation process of CPCs. As a consequence, it can be concluded that the experimental design of current in vitro degradation studies does not allow for correlation to (pre-)clinical studies.

Phase Diagram for a Four-Component System of Pentanedioic, Hexanedioic, Nonanedioic, and Decanedioic Acids

NASA Astrophysics Data System (ADS)

Kolyado, A. V.; Alenova, S. M.; Garkushin, I. K.

2018-05-01

Phase equilibria in a four-component system of pentanedioic, hexanedioic, nonanedioic, and decanedioic acids are studied via differential thermal analysis. The determined eutectic composition is pentanedioic acid, 48.1 wt %; hexanedioic acid, 10.0 wt %; nonanedioic acid, 25.7 wt %; and decanedioic acid, 16.2 wt %. The melting point of the eutectic mixture is 63.1°C.

Spectral analysis of the structure of ultradispersed diamonds

NASA Astrophysics Data System (ADS)

Uglov, V. V.; Shimanski, V. I.; Rusalsky, D. P.; Samtsov, M. P.

2008-07-01

The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles changes during the treatment.

Microstructure characterization of multi-phase composites and utilization of phase change materials and recycled rubbers in cementitious materials

NASA Astrophysics Data System (ADS)

Meshgin, Pania

2011-12-01

This research focuses on two important subjects: (1) Characterization of heterogeneous microstructure of multi-phase composites and the effect of microstructural features on effective properties of the material. (2) Utilizations of phase change materials and recycled rubber particles from waste tires to improve thermal properties of insulation materials used in building envelopes. Spatial pattern of multi-phase and multidimensional internal structures of most composite materials are highly random. Quantitative description of the spatial distribution should be developed based on proper statistical models, which characterize the morphological features. For a composite material with multi-phases, the volume fraction of the phases as well as the morphological parameters of the phases have very strong influences on the effective property of the composite. These morphological parameters depend on the microstructure of each phase. This study intends to include the effect of higher order morphological details of the microstructure in the composite models. The higher order statistics, called two-point correlation functions characterize various behaviors of the composite at any two points in a stochastic field. Specifically, correlation functions of mosaic patterns are used in the study for characterizing transport properties of composite materials. One of the most effective methods to improve energy efficiency of buildings is to enhance thermal properties of insulation materials. The idea of using phase change materials and recycled rubber particles such as scrap tires in insulation materials for building envelopes has been studied.

Modern Material Analysis Instruments Add a New Dimension to Materials Characterization and Failure Analysis

NASA Technical Reports Server (NTRS)

Panda, Binayak

2009-01-01

Modern analytical tools can yield invaluable results during materials characterization and failure analysis. Scanning electron microscopes (SEMs) provide significant analytical capabilities, including angstrom-level resolution. These systems can be equipped with a silicon drift detector (SDD) for very fast yet precise analytical mapping of phases, as well as electron back-scattered diffraction (EBSD) units to map grain orientations, chambers that admit large samples, variable pressure for wet samples, and quantitative analysis software to examine phases. Advanced solid-state electronics have also improved surface and bulk analysis instruments: Secondary ion mass spectroscopy (SIMS) can quantitatively determine and map light elements such as hydrogen, lithium, and boron - with their isotopes. Its high sensitivity detects impurities at parts per billion (ppb) levels. X-ray photo-electron spectroscopy (XPS) can determine oxidation states of elements, as well as identifying polymers and measuring film thicknesses on coated composites. This technique is also known as electron spectroscopy for chemical analysis (ESCA). Scanning Auger electron spectroscopy (SAM) combines surface sensitivity, spatial lateral resolution (10 nm), and depth profiling capabilities to describe elemental compositions of near and below surface regions down to the chemical state of an atom.

Enhancement of electrical conductivity by changing phase morphology for composites consisting of polylactide and poly(ε-caprolactone) filled with acid-oxidized multiwalled carbon nanotubes.

PubMed

Xu, Zhaohua; Zhang, Yaqiong; Wang, Zhigang; Sun, Ning; Li, Heng

2011-12-01

Composites consisting of polylactide (PLA) and poly(ε-caprolactone) (PCL) filled with acid-oxidized multiwalled carbon nanotubes (A-MWCNTs) were prepared through melt compounding. Phase morphologies of PLA/PCL/A-MWCNT composites with different contents of filled A-MWCNTs and PCL compositions were mainly observed by scanning electron microscope. The results show that A-MWCNTs are selectively dispersed in the PCL phase, regardingless of PCL phase domain sizes. For PLA/PCL/A-MWCNT composites with fixed PLA/PCL ratio of 95/5, the dispersed PCL phase domain sizes in the PLA matrix decrease even though a small content of A-MWCNTs is added, compared with PLA/PCL blend with the same composition, indicating that A-MWCNTs effectively prevent from coalescence of the dispersed PCL phase domains. With filling of 1.0 wt % A-MWCNTs, an interesting change of electrical conductivity for PLA/PCL/A-MWCNT composites is observed, in which the maximum conductivity is observed for PLA/PCL/A-MWCNT composite with PLA/PCL ratio of 60/40. The result is well-explained by the formed cocontinuous phase morphology and effective A-MWCNT content. © 2011 American Chemical Society

Composite, ordered material having sharp surface features

DOEpatents

D'Urso, Brian R.; Simpson, John T.

2006-12-19

A composite material having sharp surface features includes a recessive phase and a protrusive phase, the recessive phase having a higher susceptibility to a preselected etchant than the protrusive phase, the composite material having an etched surface wherein the protrusive phase protrudes from the surface to form a sharp surface feature. The sharp surface features can be coated to make the surface super-hydrophobic.

μX-ray fluorescence analysis of traces and calcium phosphate phases on tooth tartar interfaces using synchrotron radiation

NASA Astrophysics Data System (ADS)

Abraham, J. A.; Grenón, M. S.; Sánchez, H. J.; Valentinuzzi, M. C.; Perez, C. A.

2007-07-01

Hard dental tissues like dentine and cementum with calcified deposits (dental calculi) were studied in several human dental pieces of adult individuals from the same geographic region. A couple of cross cuts were performed at dental root level resulting in a planar slice with calculus and dental tissue exposed for analysis. The elemental content along a linear path crossing the dentine-cementum-tartar interfaces and also all over a surface was measured by X-ray fluorescence microanalysis using synchrotron radiation (μSRXRF). The concentration of elemental traces like K, V, Cu, Zn, As, Br and Sr showed different features on the analyzed regions. The possible connections with the dynamic of mineralization and biological implications are discussed. The concentrations of major elements Ca and P were also determined and the measured Ca/P molar ratio was used to estimate the average composition of calcium phosphate phases in the measured points. A deeper knowledge of the variations of the elemental compositions and the changes of the different phases will help to a better understanding of the scarcely known mechanism of calculus growing.

A study of the effects of solid phase reactions on the thermal degradation and ballistic properties of solid propellants

NASA Technical Reports Server (NTRS)

Schmidt, W. G.

1974-01-01

The thermal stability of perchlorate composite propellants was studied at 135 and 170 C. The experimental efforts were concentrated on determining the importance of heterogeneous oxidizer-fuel reactions in the thermal degradation process. The experimental approach used to elucidate the mechanisms by which the oxidizer fuel composites thermally degrade was divided into two parts: (1) keeping the fuel constant and varying the nature of the oxidizers, and (2) holding the oxidizer constant and varying the fuel components. The fuel component primarily utilized in the first phase was polyethylene. Oxidizers included KClO4, KClO3, NH4ClO4 and NH4ClO4 doped with materials such as chlorate, phosphate and arsenate. In the second phase the oxidizer used was primarily NH4ClO4 while the fuels included saturated and unsaturated polybutadiene prepolymers and a series of bonding agents. Techniques employed in the current study include thermogravimetric measurements, differential thermal analysis, infrared, mass spectrometry, electron microscopy, and appropriate wet chemical analysis.

Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data.

PubMed

Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

2009-04-03

An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLC-GCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition.

Methods for improved forewarning of critical events across multiple data channels

DOEpatents

Hively, Lee M [Philadelphia, TN

2007-04-24

This disclosed invention concerns improvements in forewarning of critical events via phase-space dissimilarity analysis of data from mechanical devices, electrical devices, biomedical data, and other physical processes. First, a single channel of process-indicative data is selected that can be used in place of multiple data channels without sacrificing consistent forewarning of critical events. Second, the method discards data of inadequate quality via statistical analysis of the raw data, because the analysis of poor quality data always yields inferior results. Third, two separate filtering operations are used in sequence to remove both high-frequency and low-frequency artifacts using a zero-phase quadratic filter. Fourth, the method constructs phase-space dissimilarity measures (PSDM) by combining of multi-channel time-serial data into a multi-channel time-delay phase-space reconstruction. Fifth, the method uses a composite measure of dissimilarity (C.sub.i) to provide a forewarning of failure and an indicator of failure onset.

Artefacts in geometric phase analysis of compound materials.

PubMed

Peters, Jonathan J P; Beanland, Richard; Alexe, Marin; Cockburn, John W; Revin, Dmitry G; Zhang, Shiyong Y; Sanchez, Ana M

2015-10-01

The geometric phase analysis (GPA) algorithm is known as a robust and straightforward technique that can be used to measure lattice strains in high resolution transmission electron microscope (TEM) images. It is also attractive for analysis of aberration-corrected scanning TEM (ac-STEM) images that resolve every atom column, since it uses Fourier transforms and does not require real-space peak detection and assignment to appropriate sublattices. Here it is demonstrated that, in ac-STEM images of compound materials with compositionally distinct atom columns, an additional geometric phase is present in the Fourier transform. If the structure changes from one area to another in the image (e.g. across an interface), the change in this additional phase will appear as a strain in conventional GPA, even if there is no lattice strain. Strategies to avoid this pitfall are outlined. Copyright © 2015 Elsevier B.V. All rights reserved.

Visualising phase change in a brushite-based calcium phosphate ceramic

PubMed Central

Bannerman, A.; Williams, R. L.; Cox, S. C.; Grover, L. M.

2016-01-01

The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s – Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media. PMID:27604149

Visualising phase change in a brushite-based calcium phosphate ceramic

NASA Astrophysics Data System (ADS)

Bannerman, A.; Williams, R. L.; Cox, S. C.; Grover, L. M.

2016-09-01

The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s - Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media.

Evaluation of phases in Pu-C-O and (U, Pu)-C-O systems by X-ray diffractometry and chemical analysis

NASA Astrophysics Data System (ADS)

Jain, G. C.; Ganguly, C.

1993-12-01

Preparation and characterisation of the carbides of uranium, plutonium and mixed uranium and plutonium form a part of advanced fuel development programs for fast breeder reactors. In the present study, the compositions of the phases of Pu-C-O and (U.Pu)-C-O systems have been determined by chemical analysis and lattice parameter measurement. The carbide samples have been prepared by vacuum carbothermic synthesis of tabletted oxide-graphite powder mixture. Dependence of stoichiometry of Pu 2C 3 phase on the oxygen content of Pu(C,O) phase in Pu(C,O) + Pu 2C 3 phase mixture has been evaluated. Stoichiometry and oxygen solubility of (U 0.3Pu 0.7)(C,O) phase in multiple phase mixture have been determined. Segregation of plutonium in (U,Pu) 2C 3 phase of (U,Pu)(C,O) + (U,Pu) 2C 3 phase mixture and its dependence on the oxygen content of (U,Pu)(C,O) phase have also been determined from the measurement of the lattice parameter of (U,Pu) 2C 3 phase.

QoS Composition and Decomposition Model in Uniframe

DTIC Science & Technology

2003-08-01

Architecture Tradeoff Analysis Method.………………….19 2.2 Analysis of Non-Functional Requirements at the Early Design Phase………19 2.2.1 Parmenides Framework...early design phase are discussed in the following sections. 2.2.1 Parmenides Framework In [22], an architecture-based framework is proposed for

Evaluation of laboratory powder X-ray micro-diffraction for applications in the fields of cultural heritage and forensic science.

PubMed

Svarcová, Silvie; Kocí, Eva; Bezdicka, Petr; Hradil, David; Hradilová, Janka

2010-09-01

The uniqueness and limited amounts of forensic samples and samples from objects of cultural heritage together with the complexity of their composition requires the application of a wide range of micro-analytical methods, which are non-destructive to the samples, because these must be preserved for potential late revision. Laboratory powder X-ray micro-diffraction (micro-XRD) is a very effective non-destructive technique for direct phase analysis of samples smaller than 1 mm containing crystal constituents. It compliments optical and electron microscopy with elemental micro-analysis, especially in cases of complicated mixtures containing phases with similar chemical composition. However, modification of X-ray diffraction to the micro-scale together with its application for very heterogeneous real samples leads to deviations from the standard procedure. Knowledge of both the limits and the phenomena which can arise during the analysis is crucial for the meaningful and proper application of the method. We evaluated basic limits of micro-XRD equipped with a mono-capillary with an exit diameter of 0.1 mm, for example the size of irradiated area, appropriate grain size, and detection limits allowing identification of given phases. We tested the reliability and accuracy of quantitative phase analysis based on micro-XRD data in comparison with conventional XRD (reflection and transmission), carrying out experiments with two-phase model mixtures simulating historic colour layers. Furthermore, we demonstrate the wide use of micro-XRD for investigation of various types of micro-samples (contact traces, powder traps, colour layers) and we show how to enhance data quality by proper choice of experiment geometry and conditions.

[Spectroscopic Research on Slag Nanocrystal Glass Ceramics Containing Rare Earth Elements].

PubMed

Ouyang, Shun-li; Li, Bao-wei; Zhang, Xue-feng; Jia, Xiao-lin; Zhao, Ming; Deng, Lei-bo

2015-08-01

The research group prepared the high-performance slag nanocrystal glass ceramics by utilizing the valuable elements of the wastes in the Chinese Bayan Obo which are characterized by their symbiotic or associated existence. In this paper, inductively coupled plasma emission spectroscopy (ICP), X-ray diffraction (XRD), Raman spectroscopy (Raman) and scanning electron microscopy (SEM) are all used in the depth analysis for the composition and structure of the samples. The experiment results of ICP, XRD and SEM showed that the principal crystalline phase of the slag nanocrystal glass ceramics containing rare earth elements is diopside, its grain size ranges from 45 to 100 nm, the elements showed in the SEM scan are basically in consistent with the component analysis of ICP. Raman analysis indicated that its amorphous phase is a three-dimensional network structure composed by the structural unit of silicon-oxy tetrahedron with different non-bridging oxygen bonds. According to the further analysis, we found that the rare earth microelement has significant effect on the network structure. Compared the nanocrystal slag glass ceramic with the glass ceramics of similar ingredients, we found that generally, the Raman band wavenumber for the former is lower than the later. The composition difference between the glass ceramics and the slag nanocrystal with the similar ingredients mainly lies on the rare earth elements and other trace elements. Therefore, we think that the rare earth elements and other trace elements remains in the slag nanocrystal glass ceramics have a significant effect on the network structure of amorphous phase. The research method of this study provides an approach for the relationship among the composition, structure and performance of the glass ceramics.

Qualitative Analysis of Microbial Dynamics during Anaerobic Digestion of Microalgal Biomass in a UASB Reactor

PubMed Central

Doloman, Anna; Soboh, Yousef; Walters, Andrew J.; Sims, Ronald C.

2017-01-01

Anaerobic digestion (AD) is a microbiologically coordinated process with dynamic relationships between bacterial players. Current understanding of dynamic changes in the bacterial composition during the AD process is incomplete. The objective of this research was to assess changes in bacterial community composition that coordinates with anaerobic codigestion of microalgal biomass cultivated on municipal wastewater. An upflow anaerobic sludge blanket reactor was used to achieve high rates of microalgae decomposition and biogas production. Samples of the sludge were collected throughout AD and extracted DNA was subjected to next-generation sequencing using methanogen mcrA gene specific and universal bacterial primers. Analysis of the data revealed that samples taken at different stages of AD had varying bacterial composition. A group consisting of Bacteroidales, Pseudomonadales, and Enterobacteriales was identified to be putatively responsible for the hydrolysis of microalgal biomass. The methanogenesis phase was dominated by Methanosarcina mazei. Results of observed changes in the composition of microbial communities during AD can be used as a road map to stimulate key bacterial species identified at each phase of AD to increase yield of biogas and rate of substrate decomposition. This research demonstrates a successful exploitation of methane production from microalgae without any biomass pretreatment. PMID:29259629

A nano lamella NbTi–NiTi composite with high strength

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

Jiang, Jiang; Jiang, Daqiang; Hao, Shijie

A hypereutectic Nb60Ti24Ni16 (at%) alloy was prepared by vacuum induction melting, and a nano lamellae NbTi-NiTi composite was obtained by hot-forging and wire-drawing of the ingot Microscopic analysis showed that NbTi and NiTi nano lamellae distributed alternatively in the composite, and aligned along the wire axial direction, with a high volume fraction (similar to 70%) of NbTi nano lamellae. In situ synchrotron X-ray diffraction analysis revealed that stress induced martensitic transformation occurred upon loading, which would effectively weaken the stress concentration at the interface and avoid the introduction of defects into the nano reinforced phase. Then the embedded NbTi nanomore » lamellae exhibited a high elastic strain up to 2.72%, 1.5 times as high as that of the Nb nanowires embedded in a conventional plastic matrix, and the corresponding stress carried by NbTi was evaluated as 2.53 GPa. The high volume fraction of NbTi nano lamellae improved the translation of high strength from the nano reinforced phase into bulk properties of the composite, with a platform stress of similar to 1.7 GPa and a fracture strength of similar to 1.9 GPa. (C) 2015 Elsevier B.V. All rights reserved.« less

Energetics analysis of interstitial loops in single-phase concentrated solid-solution alloys

NASA Astrophysics Data System (ADS)

Wang, Xin-Xin; Niu, Liang-Liang; Wang, Shaoqing

2018-04-01

Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.

Definitive Mineralogical Analysis of Mars Analog Rocks Using the CheMin XRD/XRF Instrument

NASA Technical Reports Server (NTRS)

Blake, D. F.; Sarrazin, P.; Bish, D. L.; Feldman, S.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

2004-01-01

Mineral identification is a critical component of Mars Astrobiological missions. Chemical or elemental data alone are not definitive because a single elemental or chemical composition or even a single bonding type can represent a range of substances or mineral assemblages. Minerals are defined as unique structural and compositional phases that occur naturally. There are about 15,000 minerals that have been described on Earth, all uniquely identifiable via diffraction methods. There are likely many minerals yet undiscovered on Earth, and likewise on Mars. If an unknown phase is identified on Mars, it can be fully characterized by structural (X-ray Diffraction, XRD) and elemental analysis (X-ray Fluorescence, XRF) without recourse to other data because XRD relies on the principles of atomic arrangement for its determinations. XRD is the principal means of identification and characterization of minerals on Earth.

Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution

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

Dongyu, Xu; Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina 29208; Xin, Cheng

2014-12-28

The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction ofmore » piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer.« less

Hafnia-rich mixed oxide ceramics of the system HfO2-ZrO2-TiO2 for heaters and heat exchangers in electrothermal thrusters: The effects of titania on selected electrical and mechanical properties of Hafnia-rich mixed oxides in the system Hafnia-Zirconia-Titania, volume 1

NASA Technical Reports Server (NTRS)

Staszak, Paul Russell; Wirtz, G. P.; Berg, M.; Brown, S. D.

1988-01-01

A study of the effects of titania on selected properties of hafnia-rich mixed oxides in the system hafnia-zirconia-titania (HZT) was made in the region 5 to 20 mol percent titania. The studied properties included electrical conductivity, thermal expansion, and fracture strength and toughness. The effects of titania on the properties were studied for the reduced state as well as the oxidized state of the sintered mixed oxides. X-ray analysis showed that the materials were not always single phase. The oxidized compositions went from being monoclinic solid solutions at low titania additions to having three phases (two monoclinic and a titanate phase) at high additions of titania. The reduced compositions showed an increasing cubic phase presence mixed with the monoclinic phase as titania was added. The electrical conductivity increased with temperature at approximately 0.1 mhos/cm at 1700 C for all compositions. The thermal expansion coefficient decreased with increasing titania as did the monoclinic to tetragonal transformation temperature. The fracture strength of the oxidized bars tended to decrease with the addition of titania owing to the presence of the second phase titania. The fracture strength of the reduced bars exhibited a minimum corresponding to a two-phase region of monoclinic and cubic phases. When the second phases were suppressed, the titania tended to increase the fracture strength slightly in both the oxidized and reduced states. The fracture toughness followed similar trends.

Thermal history-based etching

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

Simpson, John T.

A method for adjusting an etchability of a first borosilicate glass by heating the first borosilicate glass; combining the first borosilicate glass with a second borosilicate glass to form a composite; and etching the composite with an etchant. A material having a protrusive phase and a recessive phase, where the protrusive phase protrudes from the recessive phase to form a plurality of nanoscale surface features, and where the protrusive phase and the recessive phase have the same composition.

Transformation to Ni5Al3 in a 63.0 at. pct Ni-Al alloy

NASA Technical Reports Server (NTRS)

Khadkikar, P. S.; Locci, I. E.; Vedula, K.; Michal, G. M.

1993-01-01

Microstructures of 63 at. pct P/M Ni-Al alloys with a composition close to the stoichiometry of the Ni5Al3 phase were investigated using homogenized and quenched specimens aged at low temperatures for various times. Results of analyses of XRD data and electron microscopy observations were used for quantitative phase analysis, performed to calculate the (NiAl + Ni5Al3)/Ni5Al3 phase boundary locations. The measured lattice parameters of Ni5Al3 phase formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

Phase composition and in vitro bioactivity of porous implants made of bioactive glass S53P4.

PubMed

Fagerlund, S; Massera, J; Moritz, N; Hupa, L; Hupa, M

2012-07-01

This work studied the influence of sintering temperature on the phase composition, compression strength and in vitro properties of implants made of bioactive glass S53P4. The implants were sintered within the temperature range 600-1000°C. Over the whole temperature range studied, consolidation took place mainly via viscous flow sintering, even though there was partial surface crystallization. The mechanical strength of the implants was low but increased with the sintering temperature, from 0.7 MPa at 635°C to 10 MPa at 1000°C. Changes in the composition of simulated body fluid (SBF), the immersion solution, were evaluated by pH measurements and ion analysis using inductively coupled plasma optical emission spectrometry. The development of a calcium phosphate layer on the implant surfaces was verified using scanning electron microscopy-electron-dispersive X-ray analysis. When immersed in SBF, a calcium phosphate layer formed on all the samples, but the structure of this layer was affected by the surface crystalline phases. Hydroxyapatite formed more readily on amorphous and partially crystalline implants containing both primary Na(2)O·CaO·2SiO(2) and secondary Na(2)Ca(4)(PO(4))(2)SiO(4) crystals than on implants containing only primary crystals. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Comparative study of biogenic and abiotic iron-containing materials

NASA Astrophysics Data System (ADS)

Cherkezova-Zheleva, Z.; Shopska, M.; Paneva, D.; Kovacheva, D.; Kadinov, G.; Mitov, I.

2016-12-01

Series of iron-based biogenic materials prepared by cultivation of Leptothrix group of bacteria in different feeding media ( Sphaerotilus-Leptothrix group of bacteria isolation medium, Adler, Lieske and silicon-iron-glucose-peptone) were studied. Control samples were obtained in the same conditions and procedures but the nutrition media were not infected with bacteria, i.e. they were sterile. Room and low temperature Mössbauer spectroscopy, powder X-ray diffraction (XRD), and infrared spectroscopy (IRS) were used to reveal the composition and physicochemical properties of biomass and respective control samples. Comparative analysis showed differences in their composition and dispersity of present phases. Sample composition included different ratio of nanodimensional iron oxyhydroxide and oxide phases. Relaxation phenomena such as superparamagnetism or collective magnetic excitation behaviour were registered for some of them. The experimental data showed that the biogenic materials were enriched in oxyhydroxides of high dispersion. Catalytic behaviour of a selected biomass and abiotic material were studied in the reaction of CO oxidation. In situ diffuse-reflectance (DR) IRS was used to monitor the phase transformations in the biomass and CO conversion.

Advanced methods for preparation and characterization of infrared detector materials

NASA Technical Reports Server (NTRS)

Broerman, J. G.; Morris, B. J.; Meschter, P. J.

1983-01-01

Crystals were prepared by the Bridgman-Stockbarger method with a wide range of crystal growth rates and temperature gradients adequate to prevent constitutional supercooling under diffusion-limited, steady-state, growth conditions. The longitudinal compositional gradients for different growth conditions and alloy compositions were calculated and compared with experimental data to develop a quantitative model of solute redistribution during the crystal growth of the alloys. Measurements were performed to ascertain the effect of growth conditions on radial compositional gradients. The pseudobinary HgTe-CdTe constitutional phase diagram was determined by precision differential-thermal-analysis measurements and used to calculate the segregation coefficient of Cd as a function of x and interface temperature. Experiments were conducted to determine the ternary phase equilibria in selected regions of the Hg-Cd-Te constitutional phase diagram. Electron and hole mobilities as functions of temperature were analyzed to establish charge-carrier scattering probabilities. Computer algorithms specific to Hg(1-x)CdxTe were developed for calculations of the charge-carrier concentration, charge-carrier mobilities, Hall coefficient, and Dermi Fermi energy as functions of x, temperature, ionized donor and acceptor concentrations, and neutral defect concentrations.

Production of Sn/SnO2/MWCNT composites by plasma oxidation after thermal evaporation from pure Sn targets onto buckypapers.

PubMed

Alaf, M; Gultekin, D; Akbulut, H

2012-12-01

In this study, tin/tinoxide/multi oxide/multi walled carbon nano tube (Sn/SnO2/MWCNT) composites were produced by thermal evaporation and then subsequent plasma oxidation. Buckypapers having controlled porosity were prepared by vacuum filtration from functionalized MWCNTs. Pure metallic tin was thermally evaporated on the buckypapers in argon atmosphere with different thicknesses. It was determined that the evaporated pure tin nano crystals were mechanically penetrated into pores of buckypaper to form a nanocomposite. The tin/MWCNT composites were subjected to plasma oxidation process at oxygen/argon gas mixture. Three different plasma oxidation times (30, 45 and 60 minutes) were used to investigate oxidation and physical and microstructural properties. The effect of coating thickness and oxidation time was investigated to understand the effect of process parameters on the Sn and SnO2 phases after plasma oxidation. Quantitative phase analysis was performed in order to determine the relative phase amounts. The structural properties were studied by field-emission gun scanning electron microscopy (FEG-SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD).

Influence of hydrophilic surfactants on the properties of multiple W/O/W emulsions.

PubMed

Schmidts, T; Dobler, D; Nissing, C; Runkel, F

2009-10-01

Multiple W/O/W emulsions for topical application using Span 80 as a lipophilic emulsifier were prepared. Several hydrophilic emulsifiers were tested in respect of their suitability for the preparation of multiple emulsions. In addition, the effect of different oil-phase compositions on emulsion stability was investigated. The physicochemical parameters of the formulations were characterized and their long-term stability was evaluated by means of rheological measurements, droplet size observations and conductivity analysis. As discovered, the modification of an oil-phase composition results in a decrease in the diffusion coefficient of water and water-soluble substances and, consequently, in enhanced stability. The influence of the release of electrolytes from the inner to the outer water phase on the emulsion stability behaviour was investigated. It was found, that the effect of the hydrophilic emulsifiers on the formulation properties is related not only to its HLB value, but rather to its chemical composition. As a result, polyethoxylated ethers of fatty alcohols (C=16-18) with HLBs between 15.3 and 16.2 appear to be the most suitable ones for creating stable formulations.

PRELIMINARY PROGRESS IN THE DEVELOPMENT OF DUCTILE-PHASE TOUGHENED TUNGSTEN FOR PLASMA-FACING MATERIALS: DUAL-PHASE FINITE ELEMENT DAMAGE MODELS

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

Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

The objective of this study is to develop a finite element continuum damage model suitable for modeling deformation, cracking, and crack bridging for W-Cu, W-Ni-Fe, and other ductile phase toughened W-composites, or more generally, any multi-phase composite structure where two or more phases undergo cooperative deformation in a composite system.

Effect of SiO2/B2O3 Ratio on the Crystallization Behavior and Dielectric Properties of Barium Strontium Titanate Glass-Ceramics Prepared by Sol-Gel Process

NASA Astrophysics Data System (ADS)

Chen, Yongzhou; Zhang, Yong; Song, Xiaozhen; Shen, Ziqin; Zhang, Tianyuan

2018-05-01

Ferroelectric glass-ceramics, with a basic composition 90 wt.% (Ba0.65Sr0.35)TiO3-10 wt.% (B2O3-nSiO2) (n = 0.5, 1, 3, 5) were synthesized by the sol-gel method and their phase development and dielectric properties were investigated by differential thermal analysis, x-ray diffraction, field emission scanning electron microscopy, dielectric temperature curves and impedance spectroscopy. From the differential thermal analysis, glass transition and crystallization behavior can be observed. From the x-ray diffraction study, two crystalline phases (Ba,Sr)TiO3 and Ba2TiSi2O8 were formed over the entire composition range of the glass-ceramics. In addition, the main crystal phase has undergone a transformation from (Ba,Sr)TiO3 to Ba2TiSi2O8 with the increase of n. A typical structure in which the crystal phase was surrounded by a glassy matrix has been observed in the scanning electron microscope images. As a result of temperature dependent dielectric property measurements, the dielectric constant increased obviously with the increase of n from 0.5 to 1. Further increasing n led to a reduction of the dielectric constant, which is in coincidence with the variation of the intensity of (Ba,Sr)TiO3 phase with n. According to the impedance spectroscopy analysis and the activation energy calculation, the relaxation peak in both Z″ and M″ data should be attributed to the crystal-glass interface, and the change of conduction mechanism with the increase of SiO2/B2O3 ratio may be attributed to the corresponding transition of the main crystal phase.

Evidence for extreme Ti-50 enrichments in primitive meteorites

NASA Technical Reports Server (NTRS)

Fahey, A.; Mckeegan, K. D.; Zinner, E.; Goswami, J. N.

1985-01-01

The results of the first high mass resolution ion microprobe study of Ti isotopic compositions in individual refractory grains from primitive carbonaceous meteorites are reported. One hibonite from the Murray carbonaceous chondrite has a 10 percent excess of Ti-50, 25 times higher than the maximum value previously reported for bulk samples of refractory inclusions from carbonaceous chondrites. The variation of the Ti compositions between different hibonite grains, and among pyroxenes from a single Allende refractory inclusion, indicates isotopic inhomogeneities over small scale lengths in the solar nebula and emphasizes the importance of the analysis of small individual phases. This heterogeneity makes it unlikely that the isotopic anomalies were carried into the solar system in the gas phase.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

DOEpatents

Smith, Douglas D.; Hiller, John M.

1998-01-01

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

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

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changesmore » in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.« less

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

DOEpatents

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

Preparation and characterization of flame retardant n-hexadecane/silicon dioxide composites as thermal energy storage materials.

PubMed

Fang, Guiyin; Li, Hui; Chen, Zhi; Liu, Xu

2010-09-15

Flame retardant n-hexadecane/silicon dioxide (SiO(2)) composites as thermal energy storage materials were prepared using sol-gel methods. In the composites, n-hexadecane was used as the phase change material for thermal energy storage, and SiO(2) acted as the supporting material that is fire resistant. In order to further improve flame retardant property of the composites, the expanded graphite (EG) was added in the composites. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine chemical structure, crystalloid phase and microstructure of flame retardant n-hexadecane/SiO(2) composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the n-hexadecane was well dispersed in the porous network of the SiO(2). The DSC results indicated that the melting and solidifying latent heats of the composites are 147.58 and 145.10 kJ/kg when the mass percentage of the n-hexadecane in the composites is 73.3%. The TGA results showed that the loading of the EG increased the charred residue amount of the composites at 700 degrees C, contributing to the improved thermal stability of the composites. It was observed from SEM photographs that the homogeneous and compact charred residue structure after combustion improved the flammability of the composites. Copyright 2010 Elsevier B.V. All rights reserved.

Analysis of fat and muscle mass in patients with inflammatory bowel disease during remission and active phase.

PubMed

Rocha, Raquel; Santana, Genoile Oliveira; Almeida, Neogélia; Lyra, Andre Castro

2009-03-01

Inflammatory bowel disease (IBD) is often associated with malnutrition. The aim of this study was to compare the body composition of outpatients with IBD during remission and active phase. In order to evaluate disease activity we used Crohn's Disease Activity Index for Crohn's disease (CD) patients and Lichtiger's Index for ulcerative colitis (UC) patients. All patients underwent the analysis of BMI, arm muscle area (AMA) and triceps plus subscapula skinfold thickness (TST+SST) to identify total, muscle and fat mass, respectively. In total 102 patients were evaluated (CD, n 50; UC, n 52) and the majority was young women. Malnutrition according to BMI was found in 14.0 % of patients with CD and 5.7 % of UC patients. Muscle mass depletion was detected in more than half of the CD and UC patients. The BMI, TST+SST and AMA values were lower in the active phase only in CD patients (P < 0.05). Fat mass depletion was associated with active phase in both CD and UC patients. Body composition parameters obtained using BMI, TST+SST and AMA were not correlated with the presence of fistula in CD patients (P>0.05). In conclusion, patients without signs of malnutrition had fat mass depletion especially in the active phase and muscle mass depletion occurred both in CD and UC patients.

Integrative analysis of gut microbiota composition, host colonic gene expression and intraluminal metabolites in aging C57BL/6J mice.

PubMed

van der Lugt, Benthe; Rusli, Fenni; Lute, Carolien; Lamprakis, Andreas; Salazar, Ethel; Boekschoten, Mark V; Hooiveld, Guido J; Müller, Michael; Vervoort, Jacques; Kersten, Sander; Belzer, Clara; Kok, Dieuwertje E G; Steegenga, Wilma T

2018-05-16

The aging process is associated with diminished colonic health. In this study, we applied an integrative approach to reveal potential interactions between determinants of colonic health in aging C57BL/6J mice. Analysis of gut microbiota composition revealed an enrichment of various potential pathobionts, including Desulfovibrio spp . , and a decline of the health-promoting Akkermansia spp . and Lactobacillus spp. during aging. Intraluminal concentrations of various metabolites varied between ages and we found evidence for an increased gut permeability at higher age. Colonic gene expression analysis suggested that during the early phase of aging (between 6 and 12 months), expression of genes involved in epithelial-to-mesenchymal transition and (re)organization of the extracellular matrix were increased. Differential expression of these genes was strongly correlated with Bifidobacterium spp. During the later phase of aging (between 12 and 28 months), gene expression profiles pointed towards a diminished antimicrobial defense and were correlated with an uncultured Gastranaerophilales spp. This study demonstrates that aging is associated with pronounced changes in gut microbiota composition and colonic gene expression. Furthermore, the strong correlations between specific bacterial genera and host gene expression may imply that orchestrated interactions take place in the vicinity of the colonic wall and potentially mediate colonic health during aging.

Molecular Analyzer for Complex Refractory Organic-Rich Surfaces (MACROS)

NASA Technical Reports Server (NTRS)

Getty, Stephanie A.; Cook, Jamie E.; Balvin, Manuel; Brinckerhoff, William B.; Li, Xiang; Grubisic, Andrej; Cornish, Timothy; Ferrance, Jerome; Southard, Adrian

2017-01-01

The Molecular Analyzer for Complex Refractory Organic-rich Surfaces, MACROS, is a novel instrument package being developed at NASA Goddard Space Flight Center. MACROS enables the in situ characterization of a sample's composition by coupling two powerful techniques into one compact instrument package: (1) laser desorption/ionization time-of-flight mass spectrometry (LDMS) for broad detection of inorganic mineral composition and non-volatile organics, and (2) liquid-phase extraction methods to gently isolate the soluble organic and inorganic fraction of a planetary powder for enrichment and detailed analysis by liquid chromatographic separation coupled to LDMS. The LDMS is capable of positive and negative ion detection, precision mass selection, and fragment analysis. Two modes are included for LDMS: single laser LDMS as the broad survey mode and two step laser mass spectrometry (L2MS). The liquid-phase extraction will be done in a newly designed extraction module (EM) prototype, providing selectivity in the analysis of a complex sample. For the sample collection, a diamond drill front end will be used to collect rock/icy powder. With all these components and capabilities together, MACROS offers a versatile analytical instrument for a mission targeting an icy moon, carbonaceous asteroid, or comet, to fully characterize the surface composition and advance our understanding of the chemical inventory present on that body.

A multiscale-based approach for composite materials with embedded PZT filaments for energy harvesting

NASA Astrophysics Data System (ADS)

El-Etriby, Ahmed E.; Abdel-Meguid, Mohamed E.; Hatem, Tarek M.; Bahei-El-Din, Yehia A.

2014-03-01

Ambient vibrations are major source of wasted energy, exploiting properly such vibration can be converted to valuable energy and harvested to power up devices, i.e. electronic devices. Accordingly, energy harvesting using smart structures with active piezoelectric ceramics has gained wide interest over the past few years as a method for converting such wasted energy. This paper provides numerical and experimental analysis of piezoelectric fiber based composites for energy harvesting applications proposing a multi-scale modeling approach coupled with experimental verification. The multi-scale approach suggested to predict the behavior of piezoelectric fiber-based composites use micromechanical model based on Transformation Field Analysis (TFA) to calculate the overall material properties of electrically active composite structure. Capitalizing on the calculated properties, single-phase analysis of a homogeneous structure is conducted using finite element method. The experimental work approach involves running dynamic tests on piezoelectric fiber-based composites to simulate mechanical vibrations experienced by a subway train floor tiles. Experimental results agree well with the numerical results both for static and dynamic tests.

A Conceptual Model for Shear-Induced Phase Behavior in Crystallizing Cocoa Butter

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

Mazzanti,G.; Guthrie, S.; Marangoni, A.

2007-01-01

We propose a conceptual model to explain the quantitative data from synchrotron X-ray diffraction experiments on the shear-induced phase behavior of cocoa butter, the main structural component of chocolate. We captured two-dimensional diffraction patterns from cocoa butter at crystallization temperatures of 17.5, 20.0, and 22.5 {sup o}C under shear rates from 45 to 1440 s{sup -1} and under static conditions. From the simultaneous analysis of the integrated intensity, correlation length, lamellar thickness, and crystalline orientation, we postulate a conceptual model to provide an explanation for the distribution of phases II, IV, V, and X and the kinetics of the process.more » As previously proposed in the literature, we assume that the crystallites grow layer upon layer of slightly different composition. The shear rate and temperature applied define these compositions. Simultaneously, the shear and temperature define the crystalline interface area available for secondary nucleation by promoting segregation and affecting the size distribution of the crystallites. The combination of these factors (composition, area, and size distribution) favors dramatically the early onset of phase V under shear and determines the proportions of phases II, IV, V, and X after the transition. The experimental observations, the methodology used, and the proposed explanation are of fundamental and industrial interest, since the structural properties of crystalline networks are determined by their microstructure and polymorphic crystalline state. Different proportions of the phases will thus result in different characteristics of the final material.« less

Study of the phase composition of nanostructures produced by the local anodic oxidation of titanium films

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

Avilov, V. I.; Ageev, O. A.; Konoplev, B. G.

2016-05-15

The results of experimental studies of the phase composition of oxide nanostructures formed by the local anodic oxidation of a titanium thin film are reported. The data of the phase analysis of titanium-oxide nanostructures are obtained by X-ray photoelectron spectroscopy in the ion profiling mode of measurements. It is established that the surface of titanium-oxide nanostructures 4.5 ± 0.2 nm in height possesses a binding energy of core levels characteristic of TiO{sub 2} (458.4 eV). By analyzing the titanium-oxide nanostructures in depth by X-ray photoelectron spectroscopy, the formation of phases with binding energies of core levels characteristic of Ti{sub 2}O{submore » 3} (456.6 eV) and TiO (454.8 eV) is established. The results can be used in developing the technological processes of the formation of a future electronic-component base for nanoelectronics on the basis of titanium-oxide nanostructures and probe nanotechnologies.« less

Testing sequential extraction methods for the analysis of multiple stable isotope systems from a bone sample

NASA Astrophysics Data System (ADS)

Sahlstedt, Elina; Arppe, Laura

2017-04-01

Stable isotope composition of bones, analysed either from the mineral phase (hydroxyapatite) or from the organic phase (mainly collagen) carry important climatological and ecological information and are therefore widely used in paleontological and archaeological research. For the analysis of the stable isotope compositions, both of the phases, hydroxyapatite and collagen, have their more or less well established separation and analytical techniques. Recent development in IRMS and wet chemical extraction methods have facilitated the analysis of very small bone fractions (500 μg or less starting material) for PO43-O isotope composition. However, the uniqueness and (pre-) historical value of each archaeological and paleontological finding lead to preciously little material available for stable isotope analyses, encouraging further development of microanalytical methods for the use of stable isotope analyses. Here we present the first results in developing extraction methods for combining collagen C- and N-isotope analyses to PO43-O-isotope analyses from a single bone sample fraction. We tested sequential extraction starting with dilute acid demineralization and collection of both collagen and PO43-fractions, followed by further purification step by H2O2 (PO43-fraction). First results show that bone sample separates as small as 2 mg may be analysed for their δ15N, δ13C and δ18OPO4 values. The method may be incorporated in detailed investigation of sequentially developing skeletal material such as teeth, potentially allowing for the investigation of interannual variability in climatological/environmental signals or investigation of the early life history of an individual.

Online differentiation of mineral phase in aerosol particles by ion formation mechanism using a LAAP-TOF single-particle mass spectrometer

NASA Astrophysics Data System (ADS)

Marsden, Nicholas A.; Flynn, Michael J.; Allan, James D.; Coe, Hugh

2018-01-01

Mineralogy of silicate mineral dust has a strong influence on climate and ecosystems due to variation in physiochemical properties that result from differences in composition and crystal structure (mineral phase). Traditional offline methods of analysing mineral phase are labour intensive and the temporal resolution of the data is much longer than many atmospheric processes. Single-particle mass spectrometry (SPMS) is an established technique for the online size-resolved measurement of particle composition by laser desorption ionisation (LDI) followed by time-of-flight mass spectrometry (TOF-MS). Although non-quantitative, the technique is able to identify the presence of silicate minerals in airborne dust particles from markers of alkali metals and silicate molecular ions in the mass spectra. However, the differentiation of mineral phase in silicate particles by traditional mass spectral peak area measurements is not possible. This is because instrument function and matrix effects in the ionisation process result in variations in instrument response that are greater than the differences in composition between common mineral phases.In this study, we introduce a novel technique that enables the differentiation of mineral phase in silicate mineral particles by ion formation mechanism measured from subtle changes in ion arrival times at the TOF-MS detector. Using a combination of peak area and peak centroid measurements, we show that the arrangement of the interstitial alkali metals in the crystal structure, an important property in silicate mineralogy, influences the ion arrival times of elemental and molecular ion species in the negative ion mass spectra. A classification scheme is presented that allowed for the differentiation of illite-smectite, kaolinite and feldspar minerals on a single-particle basis. Online analysis of mineral dust aerosol generated from clay mineral standards produced mineral fractions that are in agreement with bulk measurements reported by traditional XRD (X-ray diffraction) analysis.

A Comparison between Growth Morphology of "Eutectic" Cells/Dendrites and Single-Phase Cells/Dendrites

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Raj, S. V.; Locci, I. E.

2003-01-01

Directionally solidified (DS) intermetallic and ceramic-based eutectic alloys with an in-situ composite microstructure containing finely distributed, long aspect ratio, fiber, or plate reinforcements are being seriously examined for several advanced aero-propulsion applications. In designing these alloys, additional solutes need to be added to the base eutectic composition in order to improve heir high-temperature strength, and provide for adequate toughness and resistance to environmental degradation. Solute addition, however, promotes instability at the planar liquid-solid interface resulting in the formation of two-phase eutectic "colonies." Because morphology of eutectic colonies is very similar to the single-phase cells and dendrites, the stability analysis of Mullins and Sekerka has been extended to describe their formation. Onset of their formation shows a good agreement with this approach; however, unlike the single-phase cells and dendrites, there is limited examination of their growth speed dependence of spacing, morphology, and spatial distribution. The purpose of this study is to compare the growth speed dependence of the morphology, spacing, and spatial distribution of eutectic cells and dendrites with that for the single-phase cells and dendrites.

Spatial-phase-modulation-based study of polyvinyl-alcohol/acrylamide photopolymers in the low spatial frequency range.

PubMed

Gallego, Sergi; Márquez, André; Méndez, David; Marini, Stephan; Beléndez, Augusto; Pascual, Inmaculada

2009-08-01

Photopolymers are appealing materials for the fabrication of diffractive optical elements (DOEs). We evaluate the possibilities of polyvinyl-alcohol/acrylamide-based photopolymers to store diffractive elements with low spatial frequencies. We record gratings with different spatial frequencies in the material and analyze the material behavior measuring the transmitted and the reflected orders as a function of exposition. We study two different compositions for the photopolymer, with and without a cross-linker. The values of diffraction efficiency achieved for both compositions make the material suitable to record DOEs with long spatial periods. Assuming a Fermi-Dirac-function-based profile, we fitted the diffracted intensities (up to the eighth order) to obtain the phase profile of the recorded gratings. This analysis shows that it is possible to achieve a phase shift larger than 2pi rad with steep edges in the periodic phase profile. In the case of the measurements in reflection, we have obtained information dealing with the surface profile, which show that it has a smooth shape with an extremely large phase-modulation depth.

Impact melting of the Cachari eucrite 3.0 Gy ago

NASA Technical Reports Server (NTRS)

Bogard, D. D.; Taylor, G. J.; Keil, K.; Smith, M. R.; Schmitt, R. A.

1985-01-01

The chemical compositions and Ar-isotope gas-retention ages of host phase and glass veins in the Cachari eucrite are determined by microprobe and neutron-activation analysis and mass spectrometry, respectively. The results are presented in tables, graphs, and back-scattered electron images and characterized in detail. The compositions are found to support the thesis that the glass formed by shock melting of the host rock (or of rock having the same composition). The Ar-39/Ar-40 ages of host and glass are given as 3.04 + or - 0.07 Gyr and 3.47 + or - 0.04 Gyr, respectively; the former value is taken as the true data of melting, and the latter is attributed to incomplete postmelt degassing of Ar from the glass phase. The implications of the relative youth of this and other eucrites and howardites for the regolith history of the parent body are considered.

Volatility in the lunar crust: Trace element analyses of lunar minerals by PIXE proton microprobe

NASA Technical Reports Server (NTRS)

Norman, M. D.; Griffin, W. L.; Ryan, C. G.

1993-01-01

In situ determination of mineral compositions using microbeam techniques can characterize magma compositions through mineral-melt partitioning, and be used to investigate fine-grained or rare phases which cannot be extracted for analysis. Abundances of Fe, Mn, Sr, Ga, Zr, Y, Nb, Zn, Cu, Ni, Se, and Sb were determined for various mineral phases in a small number of lunar highlands rocks using the PIXE proton microprobe. Sr/Ga ratios of plagioclase and Mn/Zn ratios of mafic silicates show that the ferroan anorthosites and Mg-suite cumulates are depleted in volatile lithophile elements to about the same degree compared with chondrites and the Earth. This links the entire lunar crust to common processes or source compositions. In contrast, secondary sulfides in Descartes breccia clasts are enriched in chalcophile elements such as Cu, Zn, Ni, Se, and Sb, and represent a potential resource in the lunar highlands.

Failure of composite plates under static biaxial planar loading

NASA Technical Reports Server (NTRS)

Waas, Anthony M.; Khamseh, Amir R.

1992-01-01

The project involved detailed investigations into the failure mechanisms in composite plates as a function of hole size (holes centrally located in the plates) under static loading. There were two phases to the project, the first dealing with uniaxial loads along the fiber direction, and the second dealing with coplanar biaxial loading. Results for the uniaxial tests have been reported and published previously, thus this report will place emphasis on the second phase of the project, namely the biaxial tests. The composite plates used in the biaxial loading experiments, as well as the uniaxial, were composed of a single ply unidirectional graphite/epoxy prepreg sandwiched between two layers of transparent thermoplastic. This setup enabled us to examine the failure initiation and propagation modes nondestructively, during the test. Currently, similar tests and analysis of results are in progress for graphite/epoxy cruciform shaped flat laminates. The results obtained from these tests will be available at a later time.

DC Electric Arc Furnace Application for Production of Nickel-Boron Master Alloys

NASA Astrophysics Data System (ADS)

Alkan, Murat; Tasyürek, Kerem Can; Bugdayci, Mehmet; Turan, Ahmet; Yücel, Onuralp

2017-09-01

In this study, nickel-boron (Ni-B) alloys were produced via a carbothermic reduction starting from boric acid (H3BO3) with high-purity nickel oxide (NiO), charcoal, and wood chips in a direct current arc furnace. In electric arc furnace experiments, different starting mixtures were used, and their effects on the chemical compositions of the final Ni-B alloys were investigated. After the reduction and melting stages, Ni-B alloys were obtained by tapping from the bottom of the furnace. The samples from the designated areas were also taken and analyzed. The chemical composition of the final alloys and selected samples were measured with wet chemical analysis. The Ni-B alloys had a composition of up to 14.82 mass% B. The phase contents of the final alloys and selected samples were measured using x-ray diffraction (XRD). The XRD data helped predict possible reactions and reaction mechanisms. The material and energy balance calculations were made via the XRD Rietveld and chemical compositions. Nickel boride phases started to form 600 mm below the surface. The targeted NiB phase was detected at the tapping zone of the crucible (850-900 mm depth). The energy consumption was 1.84-4.29 kWh/kg, and the electrode consumption was 10-12 g/kg of raw material charged.

Composite (La0.45Nd0.25)Sr0.3MnO3/5CuO materials for magnetic refrigeration applications

NASA Astrophysics Data System (ADS)

El Maalam, K.; Balli, M.; Habouti, S.; Dietze, M.; Hamedoun, M.; Hlil, E.-K.; Es-Souni, M.; El Kenz, A.; Benyoussef, A.; Mounkachi, O.

2018-03-01

In this work, the magnetocaloric properties of (La0.45Nd0.25)Sr0.3MnO3 (LNSMO)-based composites are studied. The structural, microstructural, magnetic and magnetocaloric properties of LNSMO and LNSMO/5CuO samples were investigated aiming to particularly clarify the secondary phase (CuO) role in driving the magnetocaloric behavior. The main phase LNSMO crystallizes in a rhombohedral R-3C (1 6 7) configuration. The XRD patterns of composite samples show both perovskite LNSMO and monoclinic Tenorite CuO structures. The microstructural analysis unveils that the CuO phase is mainly present in the grain boundaries and segregates region. On the other hand, it was found that the magnetocaloric effect could be significantly enhanced by adding a small amount of CuO (5% weight ratio). For a magnetic field changing from 0 to 1.5 T, the corresponding isothermal entropy change was found to be 2.55 J/kg K for the LNSMO/5CuO composite while it is only about 1.1 J/kg K for the mother material LNSMO. Our finding should inspire and open new ways for the enhancement of the magnetocaloric effect in manganites-based materials.

Model forecasting of phase composition of electrolytic alloys Co-Ni-Mn (part 1)

NASA Astrophysics Data System (ADS)

Schmidt, V. V.; Zhikhareva, I. G.

2018-03-01

With the help of four criteria for phase formation, a model forecasting of the phase composition of electrolytic alloy Co-Ni-Mn was carried out; the expected phases were calculated. The boundaries of the chemical content of the metal-solvent (Co) in these phases are determined, depending on the ratio of metal ions in the electrolyte of deposition. Model forecasting of the phase composition of Co-Ni-Mn alloys makes it possible to predict the type and number of Co phases (hexagonal close-packed - HCP-α-Co, face-centered cubic - FCC-β-Co) depending on the mole fraction of the solvent metal (Co). In the first approximation, the forecast allows one to determine the phase and chemical composition of the coating, which corresponds to the specified operational properties.

Substantiation of Epitaxial Growth of Diamond Crystals on the Surface of Carbide Fe3AlC0.66 Phase Nanoparticles

NASA Astrophysics Data System (ADS)

Dzevin, Ievgenij M.; Mekhed, Alexander A.

2017-03-01

Samples of Fe-Al-C alloys of varying composition were synthesized under high pressures and temperatures. From X-ray analysis data, only K-phase with usual for it average parameter of elemental lattice cell, a = 0.376 nm, carbide Fe3C and cubic diamond reflexes were present before and after cooling to the temperature of liquid nitrogen.

Diagenetic and compositional controls of wettability in siliceous sedimentary rocks, Monterey Formation, California

NASA Astrophysics Data System (ADS)

Hill, Kristina M.

Modified imbibition tests were performed on 69 subsurface samples from Monterey Formation reservoirs in the San Joaquin Valley to measure wettability variation as a result of composition and silica phase change. Contact angle tests were also performed on 6 chert samples from outcrop and 3 nearly pure mineral samples. Understanding wettability is important because it is a key factor in reservoir fluid distribution and movement, and its significance rises as porosity and permeability decrease and fluid interactions with reservoir grain surface area increase. Although the low permeability siliceous reservoirs of the Monterey Formation are economically important and prolific, a greater understanding of factors that alter their wettability will help better develop them. Imbibition results revealed a strong trend of decreased wettability to oil with increased detrital content in opal-CT phase samples. Opal-A phase samples exhibited less wettability to oil than both opal-CT and quartz phase samples of similar detrital content. Subsurface reservoir samples from 3 oil fields were crushed to eliminate the effect of capillary pressure and cleansed of hydrocarbons to eliminate wettability alterations by asphaltene, then pressed into discs of controlled density. Powder discs were tested for wettability by dispensing a controlled volume of water and motor oil onto the surface and measuring the time required for each fluid to imbibe into the sample. The syringe and software of a CAM101 tensiometer were used to control the amount of fluid dispensed onto each sample, and imbibition completion times were determined by high-speed photography for water drops; oil drop imbibition was significantly slower and imbibition was timed and determined visually. Contact angle of water and oil drops on polished chert and mineral sample surfaces was determined by image analysis and the Young-Laplace equation. Oil imbibition was significantly slower with increased detrital composition and faster with increased silica content in opal-CT and quartz phase samples, implying decreased wettability to oil with increased detrital (clay) content. However, contact angle tests showed that opal-CT is more wetting to oil with increased detritus and results for oil on quartz-phase samples were inconsistent between different proxies for detritus over their very small compositional range. Water contact angle trends also showed inconsistent wetting trends compared to imbibition tests. We believe this is because the small range in bulk detrital composition between the "pure" samples used in contact angle tests was close to analytical error and because small-scale spatial compositional variability may be significant enough to effect wettability. These experiments show that compositional variables significantly affect wettability, outweighing the effect of silica phase.

Carbon and Sulfur Isotopic Composition of Yellowknife Bay Sediments: Measurements by the Sample Analysis at Mars (SAM) Quadrupole Mass Spectrometer

NASA Technical Reports Server (NTRS)

Franz, H. B.; Mahaffy, P. R.; Stern, J. C.; Eigenbrode, J. L.; Steele, A.; Ming, D. W.; McAdam, A. C.; Freissinet, C.; Glavin, D. P.; Archer, P. D.;

A pressure ulcer and fall rate quality composite index for acute care units: A measure development study.

PubMed

Boyle, Diane K; Jayawardhana, Ananda; Burman, Mary E; Dunton, Nancy E; Staggs, Vincent S; Bergquist-Beringer, Sandra; Gajewski, Byron J

2016-11-01

Composite indices are single measures that combine the strengths of two or more individual measures and provide broader, easy-to-use measures for evaluation of provider performance and comparisons across units and hospitals to support quality improvement. The study objective was to develop a unit-level inpatient composite nursing care quality performance index-the Pressure Ulcer and Fall Rate Quality Composite Index. Two-phase measure development study. 5144 patient care units in 857 United States hospitals participating in the National Database of Nursing Quality Indictors ® during the year 2013. The Pressure Ulcer and Fall Rate Quality Composite Index was developed in two phases. In Phase 1 the formula was generated using a utility function and generalized penalty analysis. Experts with experience in healthcare quality measurement provided the point of indicator equivalence. In Phase 2 initial validity evidence was gathered based on hypothesized relationships between the Pressure Ulcer and Fall Rate Quality Composite Index and other variables using two-level (unit, hospital) hierarchical linear mixed modeling. The Pressure Ulcer and Fall Rate Quality Composite Index=100-PUR-FR, where PUR is pressure ulcer rate and FR is total fall rate. Higher scores indicate better quality. Bland-Altman plots demonstrated agreement between pairs of experts and provided evidence for inter-rater reliability of the formula. The validation process demonstrated that higher registered nurse skill mix, higher percent of registered nurses with a baccalaureate in nursing or higher degree, higher percent of registered nurses with national specialty certification, and lower percent of hours supplied by agency staff were significantly associated with higher Pressure Ulcer and Fall Rate Quality Composite Index scores. Higher percentages of unit patients at risk for a hospital-acquired pressure ulcer and higher unit rates of physical restraint use were not associated with higher Pressure Ulcer and Fall Rate Quality Composite Index scores. The Pressure Ulcer and Fall Rate Quality Composite Index is a step toward providing a more holistic perspective of unit level nursing quality than individual measures and may help nurses nursing administrators obtain a broader view of which patient care units are the higher and lower performers. Further study is needed to examine the usability of the Pressure Ulcer and Fall Rate Quality Composite Index. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

A PRESSURE ULCER AND FALL RATE QUALITY COMPOSITE INDEX FOR ACUTE CARE UNITS: A MEASURE DEVELOPMENT STUDY

PubMed Central

Jayawardhana, Ananda; Burman, Mary E.; Dunton, Nancy E.; Staggs, Vincent S.; Bergquist-Beringer, Sandra; Gajewski, Byron J.

2016-01-01

Background Composite indices are single measures that combine the strengths of two or more individual measures and provide broader, easy-to-use measures for evaluation of provider performance and comparisons across units and hospitals to support quality improvement. Objective The study objective was to develop a unit-level inpatient composite nursing care quality performance index – the Pressure Ulcer and Fall Rate Quality Composite Index. Design Two-phase measure development study. Settings 5,144 patient care units in 857 United States hospitals participating in the National Database of Nursing Quality Indictors® during the year 2013. Methods The Pressure Ulcer and Fall Rate Quality Composite Index was developed in two phases. In Phase 1 the formula was generated using a utility function and generalized penalty analysis. Experts with experience in healthcare quality measurement provided the point of indicator equivalence. In Phase 2 initial validity evidence was gathered based on hypothesized relationships between the Pressure Ulcer and Fall Rate Quality Composite Index and other variables using two-level (unit, hospital) hierarchical linear mixed modeling. Results The Pressure Ulcer and Fall Rate Quality Composite Index = 100 − PUR − FR, where PUR is pressure ulcer rate and FR is total fall rate. Higher scores indicate better quality. Bland-Altman plots demonstrated agreement between pairs of experts and provided evidence for inter-rater reliability of the formula. The validation process demonstrated that higher registered nurse skill mix, higher percent of registered nurses with a baccalaureate in nursing or higher degree, higher percent of registered nurses with national specialty certification, and lower percent of hours supplied by agency staff were significantly associated with higher Pressure Ulcer and Fall Rate Quality Composite Index scores. Higher percentages of unit patients at risk for a hospital-acquired pressure ulcer and higher unit rates of physical restraint use were not associated with higher Pressure Ulcer and Fall Rate Quality Composite Index scores. Conclusions The Pressure Ulcer and Fall Rate Quality Composite Index is a step toward providing a more holistic perspective of unit level nursing quality than individual measures and may help nurses nursing administrators obtain a broader view of which patient care units are the higher and lower performers. Further study is needed to examine the usability of the Pressure Ulcer and Fall Rate Quality Composite Index. PMID:27607602

An Investigation of Reliability Models for Ceramic Matrix Composites and their Implementation into Finite Element Codes

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1998-01-01

The development of modeling approaches for the failure analysis of ceramic-based material systems used in high temperature environments was the primary objective of this research effort. These materials have the potential to support many key engineering technologies related to the design of aeropropulsion systems. Monolithic ceramics exhibit a number of useful properties such as retention of strength at high temperatures, chemical inertness, and low density. However, the use of monolithic ceramics has been limited by their inherent brittleness and a large variation in strength. This behavior has motivated material scientists to reinforce the monolithic material with a ceramic fiber. The addition of a second ceramic phase with an optimized interface increases toughness and marginally increases strength. The primary purpose of the fiber is to arrest crack growth, not to increase strength. The material systems of interest in this research effort were laminated ceramic matrix composites, as well as two- and three- dimensional fabric reinforced ceramic composites. These emerging composite systems can compete with metals in many demanding applications. However, the ongoing metamorphosis of ceramic composite material systems, and the lack of standardized design data has in the past tended to minimize research efforts related to structural analysis. Many structural components fabricated from ceramic matrix composites (CMC) have been designed by "trial and error." The justification for this approach lies in the fact that during the initial developmental phases for a material system fabrication issues are paramount. Emphasis is placed on demonstrating feasibility rather than fully understanding the processes controlling mechanical behavior. This is understandable during periods of rapid improvements in material properties for any composite system. But to avoid the ad hoc approach, the analytical methods developed under this effort can be used to develop rational structural design protocols.

Chemical Composition Analysis and Product Consistency Tests of the ORP Phase 5 Nepheline Study Glasses

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

Fox, K. M.; Edwards, T. B.; Caldwell, M. E.

In this report, the Savannah River National Laboratory (SRNL) provides chemical analyses and Product Consistency Test (PCT) results for a series of simulated high-level waste glass compositions fabricated by the Pacific Northwest National Laboratory (PNNL). These data will be used in the development of improved models for the prediction of nepheline crystallization in support of the Hanford Tank Waste Treatment and Immobilization Plant (WTP).

Analysis on the Oversize Blast Furnace Desulfurization and a Sulfide Capacity Prediction Model Based on Congregated Electron Phase

NASA Astrophysics Data System (ADS)

Zhenyang, Wang; Jianliang, Zhang; Gang, An; Zhengjian, Liu; Zhengming, Cheng; Junjie, Huang; Jingwei, Zhang

2016-02-01

Through analyzed and regressed the actual productive desulfurization data from the oversize blast furnace (5500 m3) in north China, the relationship between the sulfur distribution parameters and the slag composition in actual production situation was investigated. As the slag and hot metal phases have their own balance sulfur content or sulfur partial pressure in gas phase, respectively, the non-equilibrium of sulfur among gas, slag, and metal phases leads to the transmission and distribution of sulfur. Combined with sulfur transmission reactions between gas, slag and metal phases, C/CO pairs equilibrium, and Wagner model, the measured sulfide capacity can be acquired using sulfur distribution ratio, sulfur activity coefficient, and oxygen activity in hot metal. Based on the theory of congregated electron phase, a new sulfide capacity prediction model (CEPM) has been developed, which has a good liner relationship with the measured sulfide capacity. Thus, using the burden structure for BF, the ironmaking slag composition can be obtained simply and can be used to reliably predict the ironmaking slag desulfurization ability a few hours later after charging under a certain temperature by CEPM.

Kinetics of methane hydrate replacement with carbon dioxide and nitrogen gas mixture using in situ NMR spectroscopy.

PubMed

Cha, Minjun; Shin, Kyuchul; Lee, Huen; Moudrakovski, Igor L; Ripmeester, John A; Seo, Yutaek

2015-02-03

In this study, the kinetics of methane replacement with carbon dioxide and nitrogen gas in methane gas hydrate prepared in porous silica gel matrices has been studied by in situ (1)H and (13)C NMR spectroscopy. The replacement process was monitored by in situ (1)H NMR spectra, where about 42 mol % of the methane in the hydrate cages was replaced in 65 h. Large amounts of free water were not observed during the replacement process, indicating a spontaneous replacement reaction upon exposing methane hydrate to carbon dioxide and nitrogen gas mixture. From in situ (13)C NMR spectra, we confirmed that the replacement ratio was slightly higher in small cages, but due to the composition of structure I hydrate, the amount of methane evolved from the large cages was larger than that of the small cages. Compositional analysis of vapor and hydrate phases was also carried out after the replacement reaction ceased. Notably, the composition changes in hydrate phases after the replacement reaction would be affected by the difference in the chemical potential between the vapor phase and hydrate surface rather than a pore size effect. These results suggest that the replacement technique provides methane recovery as well as stabilization of the resulting carbon dioxide hydrate phase without melting.

Detailed magnetic and structural analysis mapping a robust magnetic C 4 dome in Sr 1 - x Na x Fe 2 As 2

DOE PAGES

Taddei, K. M.; Allred, J. M.; Bugaris, D. E.; ...

2016-04-20

The recently discovered C 4 tetragonal magnetic phase in hole-doped members of the iron-based superconductors provides new insights into the origin of unconventional superconductivity. Previously observed in Ba 1-xNa xFe 2As 2 (with A = K, Na), the C 4 magnetic phase exists within the well studied C 2 spin-density wave (SDW) dome, arising just before the complete suppression of antiferromagnetic (AFM) order but after the onset of superconductivity. Here in this paper, we present detailed x-ray and neutron diffraction studies of Sr 1-xNa xFe 2As 2 (0.10 ≤ x ≤ 0.60) to determine their structural evolution and the extentmore » of the C 4 phase. Spanning Δx ~ 0.14 in composition, the C 4 phase is found to extend over a larger range of compositions, and to exhibit a significantly higher transition temperature, T r ~ 65K, than in either of the other systems in which it has been observed. The onset of this phase is seen near a composition (x~0:30) where the bonding angles of the Fe 2As 2 layers approach the perfect 109.46° tetrahedral angle. We discuss the possible role of this return to a higher symmetry environment for the magnetic iron site in triggering the magnetic reorientation and the coupled re-entrance to the tetragonal structure. Finally, we present a new phase diagram, complete with the C 4 phase, and use its observation in a third hole-doped 122 system to suggest the universality of this phase.« less

Critical aspects for the reliable headspace analysis of plants cultivated in vitro.

PubMed

Maes, K; Vercammen, J; Pham-Tuan, H; Sandra, P; Debergh, P C

2001-01-01

Various factors controlling the recoveries of volatile organic compounds in vitro headspace analysis of tomato plants (Lycopersicon esculentum Mill. 'Moneymaker'), sampled using solid phase micro-extraction, were evaluated and optimised. The variations in composition of the headspaces were determined as a function of time, and following in vitro wounding of the plant.

Gibbs Energy Modeling of Digenite and Adjacent Solid-State Phases

NASA Astrophysics Data System (ADS)

Waldner, Peter

2017-08-01

All sulfur potential and phase diagram data available in the literature for solid-state equilibria related to digenite have been assessed. Thorough thermodynamic analysis at 1 bar total pressure has been performed. A three-sublattice approach has been developed to model the Gibbs energy of digenite as a function of composition and temperature using the compound energy formalism. The Gibbs energies of the adjacent solid-state phases covelitte and high-temperature chalcocite are also modeled treating both sulfides as stoichiometric compounds. The novel model for digenite offers new interpretation of experimental data, may contribute from a thermodynamic point of view to the elucidation of the role of copper species within the crystal structure and allows extrapolation to composition regimes richer in copper than stoichiometric digenite Cu2S. Preliminary predictions into the ternary Cu-Fe-S system at 1273 K (1000 °C) using the Gibbs energy model of digenite for calculating its iron solubility are promising.

Composition and occurrence of lipid droplets in the cyanobacterium Nostoc punctiforme.

PubMed

Peramuna, Anantha; Summers, Michael L

2014-12-01

Inclusions of neutral lipids termed lipid droplets (LDs) located throughout the cell were identified in the cyanobacterium Nostoc punctiforme by staining with lipophylic fluorescent dyes. LDs increased in number upon entry into stationary phase and addition of exogenous fructose indicating a role for carbon storage, whereas high-light stress did not increase LD numbers. LD accumulation increased when nitrate was used as the nitrogen source during exponential growth as compared to added ammonia or nitrogen-fixing conditions. Analysis of isolated LDs revealed enrichment of triacylglycerol (TAG), α-tocopherol, and C17 alkanes. LD TAG from exponential phase growth contained mainly saturated C16 and C18 fatty acids, whereas stationary phase LD TAG had additional unsaturated fatty acids characteristic of whole cells. This is the first characterization of cyanobacterial LD composition and conditions leading to their production. Based upon their abnormally large size and atypical location, these structures represent a novel sub-organelle in cyanobacteria.

Influence of grinding on service properties of VT-22 powder applied in additive technologies

NASA Astrophysics Data System (ADS)

Zakharov, M. N.; Rybalko, O. F.; Romanova, O. V.; Gelchinskiy, B. R.; Il'inykh, S. A.; Krashaninin, V. A.

2017-01-01

Powder of titanium alloy (VT-22) produced by plasma-spraying was subjected to grinding to obtain powder with size less 100 microns. These powders were sprayed by plasma unit using two types of gases, namely, air and air with methane (spraying in water and sputtering of coating on steel support). Influence of grinding time on yield of powder of required fraction was studied. Morphology and phase composition of the grinded powder and plasma sprayed one were under investigation. In the result of experiments, it appears that the grinding time genuinely influences the chemical and phase compositions, but there is no effect on physical-processing properties. For powders after plasma spraying some changes of non-metal elements content were detected by chemical analysis. Using gaseous mixture of air and methane in plasma spraying unit leads to formation of a new phase in the powder according X-ray diffraction data.

Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

NASA Technical Reports Server (NTRS)

Wiesner, Valerie L.; Bansal, Narottam P.

2015-01-01

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

Proposed in situ secondary ion mass spectrometry on Mars.

PubMed

Inglebert, R L; Klossa, B; Lorin, J C; Thomas, R

1995-01-01

Secondary ion mass spectrometry is a powerful analytical tool, which has the potentiality, through molecular ion emission, of detecting minor phases, as well as the unique capability of directly measuring isotope abundances in mineral or organic phases without any prior physical, chemical or thermal processing. Applied to the in situ analysis of the Martian regolith, it can provide evidence of the presence of carbonates and, by inference (if carbonates constitute significant deposits), of past liquid water--a necessary condition for the development of life. In addition, oxygen isotopic composition of carbonates preserves a record of the temperature at which this phase precipitated and may therefore help decipher the past climatology of Mars. Detection of a carbon isotopic composition shift between carbonates and organic matter (on Earth, the result of a kinetic fractionation effect during photosynthesis) would provide a definite clue regarding the existence of a past biochemical activity on Mars.

Development of an auto-phase separable and reusable graphene oxide-potato starch based cross-linked bio-composite adsorbent for removal of methylene blue dye.

PubMed

Bhattacharyya, Amartya; Banerjee, Bhaskar; Ghorai, Soumitra; Rana, Dipak; Roy, Indranil; Sarkar, Gunjan; Saha, Nayan Ranjan; De, Sriparna; Ghosh, Tapas Kumar; Sadhukhan, Sourav; Chattopadhyay, Dipankar

2018-05-15

In this work, we report the development of a cross-linked bio-composite consisting of graphene oxide, potato starch, cross-linker glutaraldehyde and its application to adsorption of the industrial dye, methylene blue, from aqueous solution. The inexpensiveness, non-hazardous nature and easy bio-degradability are the major reasons for the selection of starch material as one of the components of the bio-composite. The bio-composite has been characterized by FTIR, SEM, XRD, particle size and zeta potential analysis. The FTIR analysis reveals the nature of the binding sites and surface morphology of the bio-composite can be understood through SEM. The auto-phase separability of the adsorbent i.e., the precipitation of the adsorbent without any mechanical means is another factor which makes this particular material very attractive as an adsorbent. Parameters like adsorbent dosage, pH, temperature, rotation speed and salt concentration have been varied to find out the suitable dye adsorption conditions. Furthermore, the time dependence of adsorption process has been analyzed using pseudo-first and pseudo-second order kinetics. The adsorption isotherms have been constructed to suggest convincing mechanistic pathway for this adsorption process. Finally, desorption studies have been successfully performed in 3 cycles, establishing the reusability of the material, which should allow the adsorbent to be economically promising for practical application in wastewater treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

Optical properties of thin fibrous PVP/SiO2 composite mats prepared via the sol-gel and electrospinning methods

NASA Astrophysics Data System (ADS)

Tański, Tomasz; Matysiak, Wiktor; Krzemiński, Łukasz; Jarka, Paweł; Gołombek, Klaudiusz

2017-12-01

The aim of the research was to create thin, nanofibrous composite mats with a polyvinylpyrrolidone (PVP) matrix, with the reinforcing phase in the form of silicon oxide (SiO2) nanoparticles. SiO2 nanopowder was obtained using the zol-gel method with a mixture of tetraethyl orthosilicate (TEOS, Si (OC2H5)), hydrochloric acid (HCl), ethanol (C3H5OH) and distilled water. The produced colloidal suspension was subjected to a drying process and a calcination process at 550 °C, resulting in an amorphous silica nanopowder with an average particle diameter of 20 nm. The morphology and structure of the manufactured SiO2 nanoparticles was tested using transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). Then, using the electrospinning method with a 15% (weight) solution of PVP in ethanol and a 15% solution of PVP/EtOH containing the produced nanoparticles equivalent to 5% of the mass concentration relative to the polymer matrix, polymer PVP nanofibres and PVP/SiO2 composite nanofibres/SiO2 nanoparticles were produced. The morphology and chemical composition of the produced polymer and composite nanofibres were tested using a scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS). The analysis of the impact of the reinforcing phase on the absorption of electromagnetic radiation was conducted on the basis of UV-vis spectra, based on which the rated values of band gaps of the produced thin fibrous mats were assessed.

Modification of Pseudobrookite Fe2-XMnxTiO5 with Solid State Reaction Method using a Mechanical Milling

NASA Astrophysics Data System (ADS)

Sarwanto, Y.; Adi, W. A.

2017-05-01

Modification of pseudobrookite Fe2-xMnxTiO5 with solid state reaction method using a mechanical milling has been synthesized. Raw materials used to prepare these samples were Fe2O3, MnCO3, and TiO2. Fe2O3 and TiO2 powders (ratio of 1:1) were mixed with MnCO3 powder at various composition of x = 0; 0.1; 0.2; 0.3; 0.4; 0.5; and 1, which each composition was added with 50 ml ethanol and then milled for 5 hours through high energy milling, after that sintered at 1000 °C for 5 hours by using box furnace. The phases of Fe2-xMnxTiO5 were measured by using X-ray diffraction (XRD) and then identified by using Match program. The crystal structure was analyzed by using the program of General Structure Analysis System (GSAS). Quality fitting of Rwp and χ2 (chi-squared) are relatively good because based on the curve of normalized error distribution looks just left background and its normal probability plot shows the value of comparable between observation and expectation. The refinement analyses of X-ray diffraction patterns showed that the samples formed single phase for x ≤ 0.3. However, the samples of x > 0.3 were multi-phases. The single phase of sample had composition of pseudobrookite Fe2TiO5 with orthorhombic structure, space group of C m c m (63), the lattice parameters of a = 3.7390 Å, b = 9.7790 Å, and c = 9.9780 Å, α = β = γ = 90°, V = 364.83 Å3, and ρ = 4.360 g.cm-3. Meanwhile, the other phase analysis for the composition of x > 0.3 is bixbyite (FeMnO3). The bixbyite has a cubic structure, under the space group of I a - 3 (206), the lattice parameters of a = b = c = 9.40 Å, α = β = γ = 90°, V = 830.58 Å3, and ρ = 5.078 g.cm-3.

LEPER: Library of Experimental PhasE Relations

NASA Astrophysics Data System (ADS)

Davis, F.; Gordon, S.; Mukherjee, S.; Hirschmann, M.; Ghiorso, M.

2006-12-01

The Library of Experimental PhasE Relations (LEPER) seeks to compile published experimental determinations of magmatic phase equilibria and provide those data on the web with a searchable and downloadable interface. Compiled experimental data include the conditions and durations of experiments, the bulk compositions of experimental charges, and the identity, compositions and proportions of phases observed, and, where available, estimates of experimental and analytical uncertainties. Also included are metadata such as the type of experimental device, capsule material, and method(s) of quantitative analysis. The database may be of use to practicing experimentalists as well as the wider Earth science community. Experimentalists may find the data useful for planning new experiments and will easily be able to compare their results to the full body of previous experimentnal data. Geologists may use LEPER to compare rocks sampled in the field with experiments performed on similar bulk composition or with experiments that produced similar-composition product phases. Modelers may use LEPER to parameterize partial melting of various lithologies. One motivation for compiling LEPER is for calibration of updated and revised versions of MELTS, however, it is hoped that the availability of LEPER will facilitate formulation and calibration of additional thermodynamic or empirical models of magmatic phase relations and phase equilibria, geothermometers and more. Data entry for LEPER is occuring presently: As of August, 2006, >6200 experiments have been entered, chiefly from work published between 1997 and 2005. A prototype web interface has been written and beta release on the web is anticipated in Fall, 2006. Eventually, experimentalists will be able to submit their new experimental data to the database via the web. At present, the database contains only data pertaining to the phase equilibria of silicate melts, but extension to other experimental data involving other fluids or sub-solidus phase equilibria may be contemplated. Also, the data are at present limited to natural or near-natural systems, but in the future, extension to synthetic (i.e., CMAS, etc.) systems is also possible. Each would depend in part on whether there is community demand for such databases. A trace element adjunct to LEPER is presently in planning stages.

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites

NASA Astrophysics Data System (ADS)

Harris, William M.; Brinkman, Kyle S.; Lin, Ye; Su, Dong; Cocco, Alex P.; Nakajo, Arata; Degostin, Matthew B.; Chen-Wiegart, Yu-Chen Karen; Wang, Jun; Chen, Fanglin; Chu, Yong S.; Chiu, Wilson K. S.

2014-04-01

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions.The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06684c

A new thermally immobilized fluorinated stationary phase for RP-HPLC.

PubMed

Maldaner, Liane; Jardim, Isabel C S F

2010-02-01

A new fluorinated stationary phase was prepared through thermal immobilization of poly(methyl-3,3,3-trifluoropropylsiloxane) onto 5 microm Kromasil silica particles. The best conditions of immobilization time and temperature were determined through a central composite design and response surface methodologies. Physical-chemical characterization using solid-state (29)Si NMR measurements, infrared spectroscopy and elemental analysis showed that the immobilization process was effective to promote a coating of the support that corresponds to a monolayer of polymer. The stationary phase presents selectivity for positional isomers and good peak shape for basic compounds.

Vacuum brazing of high volume fraction SiC particles reinforced aluminum matrix composites

NASA Astrophysics Data System (ADS)

Cheng, Dongfeng; Niu, Jitai; Gao, Zeng; Wang, Peng

2015-03-01

This experiment chooses A356 aluminum matrix composites containing 55% SiC particle reinforcing phase as the parent metal and Al-Si-Cu-Zn-Ni alloy metal as the filler metal. The brazing process is carried out in vacuum brazing furnace at the temperature of 550°C and 560°C for 3 min, respectively. The interfacial microstructures and fracture surfaces are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy spectrum analysis (EDS). The result shows that adequacy of element diffusion are superior when brazing at 560°C, because of higher activity and liquidity. Dislocations and twins are observed at the interface between filler and composite due to the different expansion coefficient of the aluminum alloy matrix and SiC particles. The fracture analysis shows that the brittle fracture mainly located at interface of filler and composites.

Microstructural, dielectric and magnetic properties of multiferroic composite system barium strontium titanate – nickel cobalt ferrite

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

Pahuja, Poonam, E-mail: poonampahuja123@gmail.com; Tandon, R. P., E-mail: ram-tandon@hotmail.com

2015-05-15

Multiferroic composites (1-x) Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} + (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (where x = 0.1, 0.2, 0.3, 0.4) has been prepared by solid state reaction method. X-ray diffraction analysis of the composite samples confirmed the presence of both barium strontium titanate (BST) and nickel cobalt ferrite (NCF) phases. FESEM images indicated the well dispersion of NCF grains among BST grains. Dielectric constant and loss of the composite samples decreases with increase in frequency following Maxwell-Wagner relaxation mechanism. Composite sample with highest ferrite content possesses highest values of remanent and saturation magnetization.

The influence of particle concentration and composition on the fractionation of 210Po and 210Pb along the North Atlantic GEOTRACES transect GA03

NASA Astrophysics Data System (ADS)

Tang, Yi; Stewart, Gillian; Lam, Phoebe J.; Rigaud, Sylvain; Church, Thomas

2017-10-01

The disequilibrium between 210Po and 210Pb has been used as a proxy for the particle flux from the upper ocean. The particle concentration and composition effect on the partitioning behavior of 210Po and 210Pb is, however, still unclear. Here, we investigate this association by comparing dissolved (< 0.45 μm) and particulate (small: 1-51 μm; large: > 51 μm) 210Po and 210Pb activity with size-fractionated major particle concentration and composition data from the US GEOTRACES GA03 zonal transect cruises. We observed inverse relationships between partition coefficients (Kd) for the radionuclides and the concentration of suspended particulate matter (SPM) in the water column, known as the ;particle concentration effect.; We examined the relationships between 210Po, 210Pb, and particle composition in the top 500 m by using Pearson pairwise correlations for individual phases and principal components analysis (PCA) for variations among multiple phases. In addition to these analyses, an end-member mixing model was developed to estimate Kd for 210Po and 210Pb in the small particulate size fraction from the compositional phases. The model predicted the range of observed Kd(Pb) well, but was unable to predict the observed Kd(Po) as consistently, possibly because of the bio-reactive nature of 210Po. Despite this, we found a strong relationship between 210Po and both CaCO3 and POM, as well as between 210Pb and both opal and lithogenic phases. All of our analyses demonstrated that the fractionation of 210Po and 210Pb differed between the margins and open ocean along the GA03 transect.

Unexpected features of exponentially growing Tobacco Bright Yellow-2 cell suspension culture in relation to excreted extracellular polysaccharides and cell wall composition.

PubMed

Issawi, Mohammad; Muhieddine, Mohammad; Girard, Celine; Sol, Vincent; Riou, Catherine

2017-10-01

This article presents a new insight about TBY-2 cells; from extracellular polysaccharides secretion to cell wall composition during cell suspension culture. In the medium of cells taken 2 days after dilution (end of lag phase), a two unit pH decrease from 5.38 to 3.45 was observed and linked to a high uronic acid (UA) amount secretion (47.8%) while, in 4 and 7 day-old spent media, pH increased and UA amounts decreased 35.6 and 42.3% UA, respectively. To attain deeper knowledge of the putative link between extracellular polysaccharide excretion and cell wall composition, we determined cell wall UA and neutral sugar composition of cells from D2 to D12 cultures. While cell walls from D2 and D3 cells contained a large amount of uronic acid (twice as much as the other analysed cell walls), similar amounts of neutral sugar were detected in cells from lag to end of exponential phase cells suggesting an enriched pectin network in young cultures. Indeed, monosaccharide composition analysis leads to an estimated percentage of pectins of 56% for D3 cell wall against 45% D7 cell walls indicating that the cells at the mid-exponential growth phase re-organized their cell wall linked to a decrease in secreted UA that finally led to a stabilization of the spent medium pH to 5.4. In conclusion, TBY-2 cell suspension from lag to stationary phase showed cell wall remodeling that could be of interest in drug interaction and internalization study.

Composite Materials for Structural Design.

DTIC Science & Technology

1982-03-01

location of failure initiation. Accurate results for the third require additional considerations not treated here. 49 ABSTRACT Tranverse Shear Deformation...mentioned competing effects so as to minimize the residual thermal stress at the termination of the cool-down phase. Elastic Analysis Consider a symmetric

DETERMINATION OF ELEMENTAL COMPOSITIONS BY HIGH RESOLUTION MASS SPECTROMETRY WITHOUT MASS CALIBRANTS

EPA Science Inventory

Widely applicable mass calibrants, including perfluorokerosene, are available for gas-phase introduction of analytes ionized by electron impact (EI) prior to analysis using high resolution mass spectrometry. Unfortunately, no all-purpose calibrants are available for recently dev...

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.

Analysis of Two-Phase Flow in Damper Seals for Cryogenic Turbopumps

NASA Technical Reports Server (NTRS)

Arauz, Grigory L.; SanAndres, Luis

1996-01-01

Cryogenic damper seals operating close to the liquid-vapor region (near the critical point or slightly su-cooled) are likely to present two-phase flow conditions. Under single phase flow conditions the mechanical energy conveyed to the fluid increases its temperature and causes a phase change when the fluid temperature reaches the saturation value. A bulk-flow analysis for the prediction of the dynamic force response of damper seals operating under two-phase conditions is presented as: all-liquid, liquid-vapor, and all-vapor, i.e. a 'continuous vaporization' model. The two phase region is considered as a homogeneous saturated mixture in thermodynamic equilibrium. Th flow in each region is described by continuity, momentum and energy transport equations. The interdependency of fluid temperatures and pressure in the two-phase region (saturated mixture) does not allow the use of an energy equation in terms of fluid temperature. Instead, the energy transport is expressed in terms of fluid enthalpy. Temperature in the single phase regions, or mixture composition in the two phase region are determined based on the fluid enthalpy. The flow is also regarded as adiabatic since the large axial velocities typical of the seal application determine small levels of heat conduction to the walls as compared to the heat carried by fluid advection. Static and dynamic force characteristics for the seal are obtained from a perturbation analysis of the governing equations. The solution expressed in terms of zeroth and first order fields provide the static (leakage, torque, velocity, pressure, temperature, and mixture composition fields) and dynamic (rotordynamic force coefficients) seal parameters. Theoretical predictions show good agreement with experimental leakage pressure profiles, available from a Nitrogen at cryogenic temperatures. Force coefficient predictions for two phase flow conditions show significant fluid compressibility effects, particularly for mixtures with low mass content of vapor. Under these conditions, an increase on direct stiffness and reduction of whirl frequency ratio are shown to occur. Prediction of such important effects will motivate experimental studies as well as a more judicious selection of the operating conditions for seals used in cryogenic turbomachinery.

Interdiffusion and Intrinsic Diffusion in the Mg-Al System

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

Brennan, Sarah; Bermudez, Katrina; Sohn, Yong Ho

2012-01-01

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electronmore » microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al3Mg2 phase.« less

Phase change compositions

DOEpatents

Salyer, Ival O.; Griffen, Charles W.

1986-01-01

Compositions containing crystalline, long chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

Phase change compositions

DOEpatents

Salyer, Ival O.

1989-01-01

Compositions containing crystalline, straight chain, alkyl hydrocarbons as phase change materials including cementitious compositions containing the alkyl hydrocarbons neat or in pellets or granules formed by incorporating the alkyl hydrocarbons in polymers or rubbers; and polymeric or elastomeric compositions containing alkyl hydrocarbons.

Preparation and characterization of phase transition/graphite foam composite materials.

PubMed

Yu, Jia; Tang, ChenLong; Yu, ZhiChao

2016-07-04

Phase transition/graphite foam (PCM/GF) composite materials are a kind of composite materials that fill graphite foam with phase change materials. In this paper, graphite foam was prepared firstly by the soft template method, the heat conductivity of which at room temperature is 5.44 W/(m∙K). Then, four phase change materials including eicosane, acetamide, xylitol, and erythritol were chosen for filling into the prepared graphite foam to obtain PCM/GF composite materials. Among the four kinds of materials, erythritol composite material has the highest melting point (118.5°C) and the highest enthalpy of fusion (266.3J/g), weight loss ratios of xylitol composite material after ten cycles is the lowest (2.1%), the compressive strength of xylitol composite material is the highest (9.08 MPa) and that of eicosane composite material is the lowest (3.32 MPa).

Relating hydrogen-bonding interactions with the phase behavior of naproxen/PVP K 25 solid dispersions: evaluation of solution-cast and quench-cooled films.

PubMed

Paudel, Amrit; Nies, Erik; Van den Mooter, Guy

2012-11-05

In this work, we investigated the relationship between various intermolecular hydrogen-bonding (H-bonding) interactions and the miscibility of the model hydrophobic drug naproxen with the hydrophilic polymer polyvinylpyrrolidone (PVP) across an entire composition range of solid dispersions prepared by quasi-equilibrium film casting and nonequilibrium melt quench cooling. The binary phase behavior in solid dispersions exhibited substantial processing method dependence. The solid state solubility of crystalline naproxen in PVP to form amorphous solid dispersions was 35% and 70% w/w naproxen in solution-cast films and quench-cooled films, respectively. However, the presence of a single mixed phase glass transition indicated the amorphous miscibility to be 20% w/w naproxen for the films, beyond which amorphous-amorphous and/or crystalline phase separations were apparent. This was further supported by the solution state interactions data such as PVP globular size distribution and solution infrared spectral profiles. The borderline melt composition showed cooling rate dependence of amorphization. The glass transition and melting point depression profiles of the system were treated with the analytical expressions based on Flory-Huggins mixing theory to interpolate the equilibrium solid solubility. FTIR analysis and subsequent spectral deconvolution revealed composition and miscibility dependent variations in the strength of drug-polymer intermolecular H-bonding. Two types of H-bonded populations were evidenced from 25% w/w and 35% w/w naproxen in solution-cast films and quench-cooled films, respectively, with the higher fraction of strongly H-bonded population in the drug rich domains of phase separated amorphous film compositions and highly drug loaded amorphous quench-cooled dispersions.

Crystal plasticity analysis of stress partitioning mechanisms and their microstructural dependence in advanced steels

DOE PAGES

Pu, Chao; Gao, Yanfei

2015-01-23

Two-phase advanced steels contain an optimized combination of high yield strength and large elongation strain at failure, as a result of stress partitioning between a hard phase (martensite) and a ductile phase (ferrite or austenite). Provided with strong interfaces between the constituent phases, the failure in the brittle martensite phase will be delayed by the surrounding geometric constraints, while the rule of mixture will dictate a large strength of the composite. To this end, the microstructural design of these composites is imperative especially in terms of the stress partitioning mechanisms among the constituent phases. Based on the characteristic microstructures ofmore » dual phase and multilayered steels, two polycrystalline aggregate models are constructed to simulate the microscopic lattice strain evolution of these materials during uniaxial tensile tests. By comparing the lattice strain evolution from crystal plasticity finite element simulations with advanced in situ diffraction measurements in literature, this study investigates the correlations between the material microstructure and the micromechanical interactions on the intergranular and interphase levels. Finally, it is found that although the applied stress will be ultimately accommodated by the hard phase and hard grain families, the sequence of the stress partitioning on grain and phase levels can be altered by microstructural designs. Implications of these findings on delaying localized failure are also discussed.« less

The crystal structure and morphology of NiO-YSZ composite that prepared from local zircon concentrate of Bangka Island

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

Rahmawati, F., E-mail: fitria@mipa.uns.ac.id; Apriyani, K.; Heraldy, E.

2016-03-29

In order to increase the economic value of local zircon concentrate from Bangka Island, NiO-YSZ was synthesized from Zirconia, ZrO{sub 2} that was prepared from local zircon concentrate. The NiO-YSZ composite was synthesized by solid state reaction method. XRD analysis equipped with Le Bail refinement was carried out to analyze the crystal structure and cell parameters of the prepared materials. The result showed that zirconia was crystallized in tetragonal structure with a space group of P42/NMC. Yttria-Stabilized-Zirconia (YSZ) was prepared by doping 8% mol yttrium oxide into zirconia and then sintered at 1250°C for 3 hours. Doping of 8% molmore » Yttria allowed phase transformation of zirconia from tetragonal into the cubic structure. Meanwhile, the composite of NiO-YSZ consists of two crystalline phases, i.e. the NiO with cubic structure and the YSZ with cubic structure. SEM analysis of the prepared materials shows that the addition of NiO into YSZ allows the morphology to become more roughness with larger grain size.« less

Correlations between the in vitro and in vivo bioactivity of the Ti/HA composites fabricated by a powder metallurgy method.

PubMed

Ning, Congqin; Zhou, Yu

2008-11-01

Ti/HA composites were successfully prepared by a powder metallurgy method and the effect of phase composition on the in vitro and in vivo bioactivity of the Ti/HA composites was investigated in the present study. The correlations between the in vitro and in vivo biological behaviors were highlighted. The results showed that the in vitro and in vivo bioactivity of the Ti/HA composites was dependent on their phase composition. The in vitro bioactivity of the Ti/HA composites was evaluated in simulated body fluid with ion concentrations similar to those of human plasma. After immersion in the simulated body fluid for a certain time, apatite precipitations formed on the surface of the composites with an initial titanium content of 50 and 70 wt.%, and no apatite was found on the surface of the composite with 30% titanium. Ti(2)O was responsible for the apatite formation on the surfaces of the composites. For in vivo analysis, Ti/HA cylinders were implanted in the metaphases of the rabbit femur. At the early stage of implantation, the new bone formed on the surface of the composite with 30% titanium was much less than that on the surfaces of the composites with 50% and 70% titanium. All the Ti/HA composites formed a chemical bone-bonding interface with the host bone by 6 months after implantation. The Ti/HA composites formed the bone-bonding interface with the surrounding bone through an apatite layer. The results in the present study suggested that the in vivo results agreed well with the in vitro results.

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

Salud, J.; Lopez, D.O.; Barrio, M.

The experimental two-component phase diagram between the orientationally disordered crystals 2-amino-2-methyl-1,3-propanediol (AMP) and 1,1,1-tris(hydroxymethyl)propane (PG) has been established from room temperature to the liquid state using thermal analysis and X-ray powder diffraction techniques. The intermolecular interactions in the orientationally disordered mixed crystals of the mentioned system and other related two-component systems are discussed by analyzing the evolution of the packing coefficient as a function of the composition. A thermodynamic analysis of the presented phase diagram and the redetermined AMP/NPG (2,2-dimethyl-1,3-propanediol) is reported on the basis of the enthalpy-entropy compensation theory.

The high squareness Sm-Co magnet having Hcb=10.6 kOe at 150°C

NASA Astrophysics Data System (ADS)

Machida, Hiroaki; Fujiwara, Teruhiko; Kamada, Risako; Morimoto, Yuji; Takezawa, Masaaki

2017-05-01

The relationship between magnetic properties and magnetic domain structures of Sm(Fe, Cu, Zr, Co)7.5 magnet was investigated. The developed Sm-Co magnet, which is conducted homogenization heat treatment at ingot state, high temperature short time sintering and long time solid solution heat treatment showed the maximum energy product, [BH]m of 34.0 MGOe and the coercivity, Hcb of 11.3 kOe at 20°C respectively. Moreover, Hcb of 10.6 kOe at 150°C was achieved. Heat treated ingot has clear 1-7 phase in mother phase from optical microscope observation. Kerr effect microscope with magnetic field applied was used to investigate magnetic domain structure. Reverse magnetic domains were generated evenly but generation of them from inside grain were not observed. Cell structure was observed by scanning transmission electron microscope and composition analysis was conducted by energy dispersive X-ray spectroscopy. Cell size was approximately 150 ˜ 300 nm, Fe and Cu were clearly separated and concentrated to 2-17 phase and 1-5 phase respectively. Moreover, Cu concentration went up to 40 at% in 1-5 phase. That means the gap of domain wall energy between 1-5 phase and 2-17 phase was increased due to microstructure control by conducting heat treatment for compositional homogeneity.

Primary Phase Field of the Pb-Doped 2223 High-Tc Superconductor in the (Bi, Pb)-Sr-Ca-Cu-O System

PubMed Central

Wong-Ng, W.; Cook, L. P.; Kearsley, A.; Greenwood, W.

1999-01-01

Both liquidus and subsolidus phase equilibrium data are of central importance for applications of high temperature superconductors in the (Bi, Pb)-Sr-Ca-Cu-O system, including material synthesis, melt processing and single crystal growth. The subsolidus equilibria of the 110 K high-Tc Pb-doped 2223 ([Bi, Pb], Sr, Ca, Cu) phase and the location of the primary phase field (crystallization field) have been determined in this study. For the quantitative determination of liquidus data, a wicking technique was developed to capture the melt for quantitative microchemical analysis. A total of 29 five-phase volumes that include the 2223 phase as a component was obtained. The initial melt compositions of these volumes range from a mole fraction of 7.3 % to 28.0 % for Bi, 11.3 % to 27.8 % for Sr, 1.2 % to 19.4 % for Pb, 9.8 % to 30.8 % for Ca, and 17.1 % to 47.0 % for Cu. Based on these data, the crystallization field for the 2223 phase was constructed using the convex hull technique. A section of this “volume” was obtained by holding two components of the composition at the median value, allowing projection on the other three axes to show the extent of the field.

Impedance and magnetoelectric characteristics of (1 - x)BaTiO3- xLa0.7Sr0.3MnO3 ( x = 0.1 and 0.3) nano-composites

NASA Astrophysics Data System (ADS)

Nayek, C.; Murugavel, P.; Dinesh Kumar, S.; Subramanian, V.

2015-08-01

We have synthesized the phase-pure (1 - x)BaTiO3- xLa0.7Sr0.3MnO3 ( x = 0.1 and 0.3) magnetoelectric composites without interdiffusion among the existing phases. The magnetic measurements revealed an anomaly at the ferroelectric Curie temperature (393 K) of BaTiO3, and the dielectric data revealed an anomaly at the ferromagnetic transition temperature (360 K) of La0.7Sr0.3MnO3 ascertaining the magnetoelectric coupling in the composite. Impedance analysis indicated dipolar polarization contributions to the dielectric spectrum with two non-Debye-type relaxations. Both the grain and grain boundary contributions were present in the system with dominant grain boundary effect in all the composites. The composites show semiconducting behavior with the barrier hopping-type conducting mechanism. To avoid the free charge carrier and the space charge contributions, the magnetoelectric response was measured at high frequency range. The maximum values of magnetoelectric voltage coefficient measured at 100 kHz were 221 and 219 mV/Oe-cm for x = 0.1 and 0.3 samples, respectively.

Phased Array Beamforming and Imaging in Composite Laminates Using Guided Waves

NASA Technical Reports Server (NTRS)

Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

2016-01-01

This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

Priority compositions of boron carbide crystals obtained by self-propagating high-temperature synthesis

NASA Astrophysics Data System (ADS)

Ponomarev, V. I.; Konovalikhin, S. V.; Kovalev, I. D.; Vershinnikov, V. I.

2015-09-01

Splitting of reflections from boron carbide has been found for the first time by an X-ray diffraction study of polycrystalline mixture of boron carbide В15- х С х , (1.5 ≤ x ≤ 3) and its magnesium derivative C4B25Mg1.42. An analysis of reflection profiles shows that this splitting is due to the presence of boron carbide phases of different compositions in the sample, which are formed during crystal growth. The composition changes from В12.9С2.1 to В12.4С2.6.

Achieving phase transformation and structure control of crystalline anatase TiO2@C hybrids from titanium glycolate precursor and glucose molecules.

PubMed

Cheng, Gang; Stadler, Florian J

2015-01-15

Considerable efforts have focused on functional TiO2@carbonaceous hybrid nanostructured materials (TiO2@C) to satisfy the future requirements of environmental photocatalysis and energy storage using these advanced materials. In this study, we developed a two-step solution-phase reaction to prepare hybrid TiO2@C with tuneable structure and composition from the hydrothermal carbonization (HTC) of glucose. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) were used to determine the crystallite size, composition, and phase purity. The results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM) showed that the morphology of the as-synthesized TiO2@C hybrids could be controlled by varying the amount of glucose, also acting as the carbon source. Based on the observations made with different glucose concentrations, a formation mechanism of nanoparticulate and nanoporous TiO2@C hybrids was proposed. In addition, the as-synthesized TiO2@C hybrids with different compositions and structures showed enhanced adsorption of visible light and improved dye-adsorption capacity, which supported their potential use as photocatalysts with good activity. This new synthetic approach, using a nanoprecursor, provides a simple and versatile way to prepare TiO2@C hybrids with tuneable composition, structures, and properties, and is expected to lead to a family of composites with designed properties. Copyright © 2014 Elsevier Inc. All rights reserved.

Phase structure of completely asymptotically free SU(Nc) models with quarks and scalar quarks

NASA Astrophysics Data System (ADS)

Hansen, F. F.; Janowski, T.; Langæble, K.; Mann, R. B.; Sannino, F.; Steele, T. G.; Wang, Z. W.

2018-03-01

We determine the phase diagram of completely asymptotically free SU (Nc) gauge theories featuring Ns complex scalars and Nf Dirac quarks transforming according to the fundamental representation of the gauge group. The analysis is performed at the maximum known order in perturbation theory. We unveil a very rich dynamics and associated phase structure. Intriguingly, we discover that the completely asymptotically free conditions guarantee that the infrared dynamics displays long-distance conformality, and in a regime when perturbation theory is applicable. We conclude our analysis by determining the quantum corrected potential of the model and summarizing the possible patterns of radiative symmetry breaking. These models are of potential phenomenological interest as either elementary or composite ultraviolet finite extensions of the standard model.

Condensed phase conversion and growth of nanorods and other materials instead of from vapor

DOEpatents

Geohegan, David B.; Seals, Roland D.; Puretzky, Alex A.; Fan, Xudong

2010-10-19

Compositions, systems and methods are described for condensed phase conversion and growth of nanorods and other materials. A method includes providing a condensed phase matrix material; and activating the condensed phase matrix material to produce a plurality of nanorods by condensed phase conversion and growth from the condensed phase matrix material instead of from vapor. The compositions are very strong. The compositions and methods provide advantages because they allow (1) formation rates of nanostructures necessary for reasonable production rates, and (2) the near net shaped production of component structures.

Phase-change composites TES for nickel-hydrogen batteries

NASA Technical Reports Server (NTRS)

Knowles, Timothy R.; Meyer, Richard A.

1993-01-01

Viewgraphs of a discussion on phase-change composites thermal energy storage (TES) for nickel-hydrogen batteries are presented. Topics covered include Ni-H2 thermal control problems; passive thermal control with TES; phase-change composites (PCC); candidate materials; design options; fabrication and freeze-melt cycling; thermal modeling; system benefits; and applications.

Preparation and study of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) composite multiferroics

NASA Astrophysics Data System (ADS)

Murtaza, Tahir; Ali, Javid; Khan, M. S.

2018-07-01

The parent and mixed spinel-perovskite composite of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) has been prepared by solid-state reaction method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, magnetometry and P-E lope tracer. The XRD results showed the formation of single phase tetragonal spinel CuFe2O4 and tetragonal perovskite BaTiO3 at room temperature, further XRD of composite 0.1CuFe2O4-0.9BaTiO3 reflects the two crystallographic phases with 1:9 ratio. The SEM micrographs show the homogeneous and uniform formation of the samples. Through EDAX analysis, the chemical composition of the sample is found to be same as the nominal composition. The high field Mossbauer data of CuFe2O4 sample shows the ferrimagnetic ordering in the sample. The observed M-H and P-E loops of the composite 0.1CuFe2O4-0.9BaTiO3 sample show the presence of spontaneous magnetization and spontaneous electric polarization indicating the multiferroic nature of the sample.

Zoning and exsolution in cumulate alkali feldspars from the eruption (12.9 Ka) of Laacher see volcano (Western Germany) as an indicator of time-scales and dynamics of carbonate-silicate unmixing

NASA Astrophysics Data System (ADS)

Sourav Rout, Smruti; Wörner, Gerhard

2017-04-01

Time-scales extracted from the detailed analysis of chemically zoned minerals provide insights into crystal ages, magma storage and compositional evolution, including mixing and unmixing events. This allows having a better understanding of pre-eruptive history of large and potentially dangerous magma chambers. We present a comprehensive study of chemical diffusion across zoning and exsolution patterns of alkali feldspars in carbonatite-bearing cognate syenites from the 6.3 km3 (D.R.E) phonolitic Laacher See Tephra (LST) eruption 12.9 ka ago. The Laacher See volcano is located in the Quaternary East Eifel volcanic field of the Paleozoic Rhenish Massif in Western Germany and has produced a compositionally variable sequence in a single eruption from a magma chamber that was zoned from mafic phonolite at the base to highly evolved, actively degassing phonolite magma at the top. Diffusion chronometry is applied to major and trace element compositions obtained on alkali feldspars from carbonate-bearing syenitic cumulates. Methods used were laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) in combination with energy-dispersive and wavelength-dispersive electron microprobe analyses (EDS & WDS-EMPA). The grey scale values extracted from multiple accumulations of back-scattered electron images represent the K/Na ratio owing to the extremely low concentrations of Ba and Sr (<30 ppm). The numerical grey scale profiles and the quantitative compositional profiles are anatomized using three different fitting models in MATLAB®, Mathematica® and Origin® to estimate related time-scales with minimized error for a temperature range of 750 deg C to 800 deg C (on the basis of existing experimental data on phase transition and phase separation). A distinctive uphill diffusive analysis is used specifically for the phase separation in the case of exsolution features (comprising of albite- and orthoclase-rich phases) in sanidines. The error values are aggregates of propagated error through calculations and the uncertainty in temperature values. Trace element compositional data of distinct feldspar compositions that are assumed to have grown before and after silicate-carbonate unmixing are used to estimate partition coefficients between carbonate and silicate melt. The resulting values correlate well with available experimental data from the literature. We will present a genetic model based on the compositional data on feldspar zonation for the process and timing of silicate-carbonate unmixing prior to eruption of the host phonolite magma.

Advanced manufacturing development of a composite empennage component for L-1011 aircraft. Phase 2: Design and analysis

NASA Technical Reports Server (NTRS)

Jackson, A. C.; Crocker, J. F.; Ekvall, J. C.; Eudaily, R. R.; Mosesian, B.; Vancleave, R. R.; Vanhamersveld, J.

1981-01-01

The composite fin design consists of two one-piece cocured covers, two one-piece cocured spars and eleven ribs. The lower ribs are truss ribs with graphite/epoxy caps and aluminum truss members. The upper three ribs are a sandwich design with graphite/epoxy face sheets and a syntactic epoxy core. The design achieves a 27% weight saving compared to the metal box. The fastener count has been reduced from over 40,000 to less than 7000. The structural integrity of the composite fin was verified by analysis and test. The static, fail-safe and flutter analyses were completed. An extensive test program has established the material behavior under a range of conditions and critical subcomponents were tested to verify the structural concepts.

Welding of a corrosion-resistant composite material based on VT14 titanium alloy obtained using an electron beam emitted into the atmosphere

NASA Astrophysics Data System (ADS)

Golkovski, M. G.; Samoylenko, V. V.; Polyakov, I. A.; Lenivtseva, O. G.; Chakin, I. K.; Komarov, P. N.; Ruktuev, A. A.

2017-01-01

The study investigates the possibility of inert gas arc welding of a double layer composite material on a titanium base with an anti-corrosive layer obtained by fused deposition of a powder mix containing tantalum and niobium over a titanium base using an electron beam emitted into the atmosphere. Butt welding and fillet welding options were tested with two types of edge preparation. Welds were subjected to a metallographic examination including a structural study and an analysis of the chemical and phase composition of the welds. A conclusion was made regarding the possibility of using welding for manufacturing of items from the investigated composite material.

Investigations on composites reinforced with HEA particles

NASA Astrophysics Data System (ADS)

Carcea, I.; Chelariu, R.; Asavei, L.; Cimpoeşu, N.; Florea, R. M.

2017-08-01

This work reports the results of investigations on the fortification with high entropy alloys particles of aluminium matrix composite materials. The properties of these materials processed by Vortex techniques primarily depend on the matrix and the volume fraction of the constituent phase. The mechanical properties, toughening mechanisms and potential applications are briefly reviewed. Traditional methods were used for the basic characterization of the composite. The microstructure of the composites were investigated by optical and scanning electron microscopy (OM, SEM). SEM analysis was performed in order to observe the microstructural evolution as a function of the HEA particles content and to identify some reasons of the presence of porosity or any irregularities within the metal matrix.

Gas and hydrocarbon vapor permeation in poly(1-trimethylsilyl-1-propyne)/poly(1-phenyl-1-propyne) blends

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

Morisato, A.; Shen, H.C.; Toy, L.G.

1996-12-31

Permeation properties of phase-separated blends prepared from glassy poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) were determined as a function of blend composition with pure hydrogen, nitrogen, oxygen, carbon dioxide, and butane. Blend permeabilities decrease significantly with increasing PPP concentration and suggest the occurrence of a phase inversion at low PPP content (5 to 20 wt%). Based on TEM analysis high-aspect-ratio (extended) PPP ellipsoidal dispersions are found in a PTMSP matrix, indicating that the phase inversion is closely related to dispersed-phase connectivity in the blends.

Distribution or adsorption: the major dilemma in reversed-phase HPLC

NASA Astrophysics Data System (ADS)

Deineka, V. I.

2008-06-01

A method is suggested for analyzing the dependences obtained for different compositions of mobile eluent system phases, their slopes and intercepts, log k( i, B) = a + b log k ( i, A), where a is the intercept for the A and B stationary phases and b is the proportionality factor. An analysis requires parallel investigation of sorbate retention on at least three stationary phases with different lengths of grafted hydrocarbon radicals. The dependence of correlation parameters on the sorbate retention mechanism is discussed. It is shown that the hypothetical dependences coincide with the experimental dependences for surface sorption of resveratrol and volume distribution of triglycerides.

Precision Electron Density Measurements in the SSX MHD Wind Tunnel

NASA Astrophysics Data System (ADS)

Suen-Lewis, Emma M.; Barbano, Luke J.; Shrock, Jaron E.; Kaur, Manjit; Schaffner, David A.; Brown, Michael R.

2017-10-01

We characterize fluctuations of the line averaged electron density of Taylor states produced by the magnetized coaxial plasma gun of the SSX device using a 632.8 nm HeNe laser interferometer. The analysis method uses the electron density dependence of the refractive index of the plasma to determine the electron density of the Taylor states. Typical magnetic field and density values in the SSX device approach about B ≅ 0.3 T and n = 0 . 4 ×1016 cm-3 . Analysis is improved from previous density measurement methods by developing a post-processing method to remove relative phase error between interferometer outputs and to account for approximately linear phase drift due to low-frequency mechanical vibrations of the interferometer. Precision density measurements coupled with local measurements of the magnetic field will allow us to characterize the wave composition of SSX plasma via density vs. magnetic field correlation analysis, and compare the wave composition of SSX plasma with that of the solar wind. Preliminary results indicate that density and magnetic field appear negatively correlated. Work supported by DOE ARPA-E ALPHA program.

Development of AlN and TiB2 Composites with Nb2O5, Y2O3 and ZrO2 as Sintering Aids

PubMed Central

González, José C.; Rodríguez, Miguel Á.; Figueroa, Ignacio A.; Villafuerte-Castrejón, María-Elena; Díaz, Gerardo C.

2017-01-01

The synthesis of AlN and TiB2 by spark plasma sintering (SPS) and the effect of Nb2O5, Y2O3 and ZrO2 additions on the mechanical properties and densification of the produced composites is reported and discussed. After the SPS process, dense AlN and TiB2 composites with Nb2O5, Y2O3 and ZrO2 were successfully prepared. X-ray diffraction analysis showed that in the AlN composites, the addition of Nb2O5 gives rise to Nb4N3 during sintering. The compound Y3Al5O12 (YAG) was observed as precipitate in the sample with Y2O3. X-ray diffraction analysis of the TiB2 composites showed TiB2 as a single phase in these materials. The maximum Vickers and toughness values were 14.19 ± 1.43 GPa and 27.52 ± 1.75 GPa for the AlN and TiB2 composites, respectively. PMID:28772681

Vector analysis of chemical variation in the lavas of Parícutin volcano, Mexico

USGS Publications Warehouse

Miesch, A.T.

1979-01-01

Compositional variations in the lavas of Parícutin volcano, Mexico, have been examined by an extended method of Q-mode factor analysis. Each sample composition is treated as a vector projected from an original eight-dimensional space into a vector system of three dimensions. The compositions represented by the vectors after projection are closely similar to the original compositions except for Na2Oand Fe2O3.The vectors in the three-dimensional system cluster about three different planes that represent three stages of compositional change in the Parícutin lavas. Because chemical data on the compositions of the minerals in the lavas are presently lacking, interpretations of the mineral phases that may have been involved in fractional crystallization are based on CIPW norm calculations. Changes during the first stage are attributed largely to the fractional crystallization of plagioclase and olivine. Changes during the second stage can be explained by the separation of plagioclase and pyroxene. Changes during the final stage may have resulted mostly from the assimilation of a granitic material, as previously proposed by R. E. Wilcox.

Synthesis of TiO2 NRs - ZnO Composite for Dye Sensitized Solar Cell Photoanodes

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Ramelan, A. H.; Hidayat, R.; Fadillah, G.; Munawaroh, H.; Saputri, L. N. M. Z.

2017-07-01

Composite of TiO2 NRs - ZnO were synthesized for DSSCs photoanode materials. TiO2 NRs was synthesized from TiO2 anatase by mechanochemical technique using ball milling process with agitation speed of 1000 rpm. While, the further hydrothermal refluxing process was conducted at 120°C under various concentration of NaOH in aqueous solution. The starting material of ZnO was prepared from ZnSO4.7H2O as a precursor. The hydrothermal treated TiO2 was added to the ZnO powder in a certain composition of 1:1, 1:2 and 2:1 (w/w), and the mixtures were then annealed at 400°C. The resulting material was characterized by X-ray diffraction (XRD), Surface area analyzer (SAA), Transmission electron microscopy (TEM), and Thermogravimetry/Differential thermal analysis (TG/DTA). The TiO2 revolution occurs from anatase phase into brookite phase. Rutile TiO2 phase was increasing when the NaOH was added at about 12 M. Nanograf of TEM showed the optimum condition for the formation of TiO2 NRs was obtained when 12 M NaOH was used. Structural transformation to 1D nanorods of TiO2 capable increase surface area up to 79 m2/g. TiO2 NRs-ZnO composite was prepared from TiO2 NRs and ZnO using comparation of TiO2 NRs: ZnO = 1:1, 1:2, dan 2:1. Anatase phase TiO2 as a single phase TiO2 was obtained in the TiO2-ZnO composite (1:1 w/w) upon heating the sample until 400°C. Difference TiO2 NRs-ZnO composite materials were investigated as good photovoltaic materials. Evaluation of the performance of DSSCs was conducted by I-V Keithley 2602A measurement indicate that photoanode built of TiO2 NRs - ZnO thin film has a higher solar cell efficiency than that of TiO2 thin film photoanode.

The complex lightcurve of 1992 NA

NASA Technical Reports Server (NTRS)

Wisniewski, Wieslaw Z.; Harris, A. W.

1994-01-01

Amor asteroid 1992 NA was monitored during three nights at a large phase angle of -65 deg. The lightcurves obtained did not reveal a repeatable curve with two maxima and two minima. However, some features suggested a periodicity with three maxima and three minima. A satisfactory composite lightcurve of this form was obtained by means of an 'eyeball' fit and by Fourier analysis. Individual and composite lightcurves are presented. The observed colors are consistent with the C class.

Composition and Molecular Weight Distribution of Carob Germ Proteins Fractions

USDA-ARS?s Scientific Manuscript database

Biochemical properties of carob germ proteins were analyzed using a combination of selective extraction, reversed-phase high performance liquid chromatography (RP-HPLC), size exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALS) and electrophoretic analysis. Using a mo...

Analysis of the chemical and physical properties of combustion aerosols: Properties overview

EPA Science Inventory

Aerosol chemical composition is remarkably complex. Combustion aerosols can comprise tens of thousands of organic compounds and fragments, refractory carbon, metals, cations, anions, salts, and other inorganic phases and substituents [Hays et al., 2004]. Aerosol organic matter no...

Compositional instability of {beta}-phase in Ni-Mn-Ga alloys

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

Chernenko, V.A.

1999-02-05

The ferromagnetic Heusler alloys of stoichiometric Ni{sub 2}MnGa and nonstoichiometric Ni-Mn-Ga chemical compositions though not containing a noble-metal, indeed, belong to {beta}-alloys which lattice stability is decided by the Hume-Rothery mechanism: electron concentration e/a measuring the decrease of the electron energy due to the pseudogap formation and size factor. The intriguing feature of Ni-Mn-Ga alloys similarly to Ti-Ni, Cu-Al-Be and Ni-Al alloys arises that transformation temperature, M{sub s}, is dramatically dependent on concentration reflecting an extremely high sensitivity of the lattice stability toward the content variation. The main purpose of present paper is an analysis of previous data concerning themore » compositional dependence of M{sub s} from the viewpoint of searching for empirical correlation between the electron concentration and stability of {beta}-phase in Ni-Mn-Ga system. This analysis will provide a confirmation of the feasibility of a reasonable explanation of seemingly random collection of alloys grouped with respect to their M{sub s} values as well as other features. The alloys of compositional range studied previously are added here to a few alloys including ones doped with V and Ge to ensure the decisive role of e/a ratio on M{sub s}. Original results about the temperature dependent resistance behavior are presented as well.« less

Characterization of emissions composition for selected household products available in Korea.

PubMed

Kwon, Ki-Dong; Jo, Wan-Kuen; Lim, Ho-Jin; Jeong, Woo-Sik

2007-09-05

The present study investigated the emission composition for 59 household products currently sold in Korea, using a headspace analysis. The chemical composition and concentrations of total volatile organic compounds (VOCs) broadly varied along with products, even within the same product category. Up to 1-17 organic compounds were detected in the headspace gas phase of any one of the products. The chemical composition of certain household products determined in the current study was different from that of other studies from other countries. Between 4 and 37 compounds were detected in the headspace gas phase of each product class. Several compounds were identified in more than one product class. Of the 59 household products analyzed, 58 emitted one or more of the 72 compounds at chromatographic peak areas above 10(4). There were 11 analytes which occurred with a frequency of more than 10%: limonene (44.2%), ethanol (30.5%), acetone (18.6%), alpha-pinene (18.6%), o,m,p-xylenes (18.6%), decane (17.0%), toluene (17.0%), beta-myrcene (11.9%), ammonia (10.2%), ethylbenzene (10.2%), and hexane (10.2%).

Structural, electrical conductivity and dielectric behavior of Na2SO4-LDT composite solid electrolyte.

PubMed

Iqbal, Mohd Z; Rafiuddin

2016-01-01

A series of composite materials of general molecular formula (1 - x) Na2SO4 - (x) LDT was prepared by solid state reaction method. The phase structure and functionalization of these materials were defined by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) respectively. Differential thermal analysis (DTA) revealed that the hump of phase transition at 250 °C has decreased while its thermal stability was enhanced. Scanning electron microscopy signifies the presence of improved rigid surfaces and interphases that are accountable for the high ionic conduction due to dispersion of LDT particles in the composite systems. Arrhenius plots of the conductance show the maximum conductivity, σ = 4.56 × 10(-4) S cm(-1) at 500 °C for the x = 0.4 composition with the lowest activation energy 0.34 eV in the temperature range of 573-773 K. The value of dielectric constant was decreased with increasing frequency and follows the usual trend.

Study of 0.1Ni0.8Zn0.2Fe2O4-0.9Pb1-3x/2LaxZr0.65Ti0.35O3 magnetoelectric composites

NASA Astrophysics Data System (ADS)

Rani, Rekha; Juneja, J. K.; Singh, Sangeeta; Raina, K. K.; Prakash, Chandra

2013-01-01

Magnetoelectric composites of nickel zinc ferrite (NZF) and La substituted lead zirconate titanate (PLZT) having representative formula 0.1Ni0.8Zn0.2Fe2O4-0.9Pb1-3x/2LaxZr0.65Ti0.35O3 (x=0, 0.01, 0.02 and 0.03) were synthesized by a conventional solid state route. X-ray diffraction analysis was carried out to confirm the coexistence of individual phases. Scanning electron microscope micrographs were taken for microstructural study of the samples. Dielectric properties were studied as a function of temperature and frequency. To study ferroelectric and magnetic ordering in composite samples, P-E and M-H hysteresis loops were recorded respectively. M-H hysteresis loops were taken for electrically poled and unpoled samples to confirm magnetoelectric coupling between the two phases (NZF and PLZT). La substitution results in significant improvement in dielectric, ferroelectric and piezoelectric properties of composite samples.

Pattern recognition and genetic algorithms for discrimination of orange juices and reduction of significant components from headspace solid-phase microextraction.

PubMed

Rinaldi, Maurizio; Gindro, Roberto; Barbeni, Massimo; Allegrone, Gianna

2009-01-01

Orange (Citrus sinensis L.) juice comprises a complex mixture of volatile components that are difficult to identify and quantify. Classification and discrimination of the varieties on the basis of the volatile composition could help to guarantee the quality of a juice and to detect possible adulteration of the product. To provide information on the amounts of volatile constituents in fresh-squeezed juices from four orange cultivars and to establish suitable discrimination rules to differentiate orange juices using new chemometric approaches. Fresh juices of four orange cultivars were analysed by headspace solid-phase microextraction (HS-SPME) coupled with GC-MS. Principal component analysis, linear discriminant analysis and heuristic methods, such as neural networks, allowed clustering of the data from HS-SPME analysis while genetic algorithms addressed the problem of data reduction. To check the quality of the results the chemometric techniques were also evaluated on a sample. Thirty volatile compounds were identified by HS-SPME and GC-MS analyses and their relative amounts calculated. Differences in composition of orange juice volatile components were observed. The chosen orange cultivars could be discriminated using neural networks, genetic relocation algorithms and linear discriminant analysis. Genetic algorithms applied to the data were also able to detect the most significant compounds. SPME is a useful technique to investigate orange juice volatile composition and a flexible chemometric approach is able to correctly separate the juices.

Synthesis and structural analysis of Fe doped TiO2 nanoparticles using Williamson Hall and Scherer Model

NASA Astrophysics Data System (ADS)

Patle, L. B.; Labhane, P. K.; Huse, V. R.; Gaikwad, K. D.; Chaudhari, A. L.

2018-05-01

The nanoparticles of Pure and doped Ti1-xFexO were synthesized by modified co-precipitation method successfully with nominal composite of x=0.0, 0.01, 0.03 and 0.05 at room temperature. The precursors were further calcined at 500°C for 6hrs in muffle furnace which results in the formation of different TiO2 phase compositions. The structural analysis carried out by XRD (Bruker D8 Cu-Kα1). X-ray peak broadening analysis was used to evaluate the crystalline sizes, the lattice parameters, atomic packing fraction, c/a ratio, X-ray density and Volume of unit cell. The Williamson Hall analysis is used to find grain size and Strain of prepared TiO2 nano particles. Crystalline TiO2 with a Tetragonal Anatase phase is confirmed by XRD results. The grain size of pure and Fe doped samples were found in the range of 10nm to 18nm. All the physical parameters of anatase tetragonal TiO2 nanoparticles were calculated more precisely using modified W-H plot a uniform deformation model (UDM). The results calculated from both the techniques were approximately similar.

Atomic-scale phase composition through multivariate statistical analysis of atom probe tomography data.

PubMed

Keenan, Michael R; Smentkowski, Vincent S; Ulfig, Robert M; Oltman, Edward; Larson, David J; Kelly, Thomas F

2011-06-01

We demonstrate for the first time that multivariate statistical analysis techniques can be applied to atom probe tomography data to estimate the chemical composition of a sample at the full spatial resolution of the atom probe in three dimensions. Whereas the raw atom probe data provide the specific identity of an atom at a precise location, the multivariate results can be interpreted in terms of the probabilities that an atom representing a particular chemical phase is situated there. When aggregated to the size scale of a single atom (∼0.2 nm), atom probe spectral-image datasets are huge and extremely sparse. In fact, the average spectrum will have somewhat less than one total count per spectrum due to imperfect detection efficiency. These conditions, under which the variance in the data is completely dominated by counting noise, test the limits of multivariate analysis, and an extensive discussion of how to extract the chemical information is presented. Efficient numerical approaches to performing principal component analysis (PCA) on these datasets, which may number hundreds of millions of individual spectra, are put forward, and it is shown that PCA can be computed in a few seconds on a typical laptop computer.

Phase diagram and electrical behavior of silicon-rich iridium silicide compounds

NASA Technical Reports Server (NTRS)

Allevato, C. E.; Vining, Cronin B.

1992-01-01

The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metalography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir3Si4, Ir3Si5 and IrSi sub about 3. The existence of Ir4Si5 could not be confirmed in this study, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi sub about 3, determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 83 +/- 1 atomic percent silicon was observed between IrSi sub about 3 and silicon. Ir3Si4 exhibits distinct metallic behavior while Ir3Si5 is semiconducting. Both and IrSi and IrSi sub about 3 exhibit nearly temperature independent electrical resistivities on the order of 5-10 x 10 exp -6 ohms-m.

Investigation on phase transitions of 1-decylammonium hydrochloride as the potential thermal energy storage material

NASA Astrophysics Data System (ADS)

Dan, Wen-Yan; Di, You-Ying; He, Dong-Hua; Liu, Yu-Pu

2011-02-01

1-Decylammonium hydrochloride was synthesized by the method of liquid phase synthesis. Chemical analysis, elemental analysis, and X-ray single crystal diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the compounds were measured with a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. Three solid-solid phase transitions have been observed at the peak temperatures of 307.52 ± 0.13, 325.02 ± 0.19, and 327.26 ± 0.07 K. The molar enthalpies and entropies of three phase transitions were determined based on the analysis of heat capacity curves. Experimental molar heat capacities were fitted to two polynomial equations of the heat capacities as a function of temperature by least square method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K based on the fitted polynomials.

Wear and friction behavior of Al-TiB2-nano-Gr hybrid composites fabricated through ultrasonic cavitation assisted stir casting

NASA Astrophysics Data System (ADS)

Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

2018-05-01

The present study reports the role of nano-graphite particles in determining wear and friction behavior of Al-TiB2-nano-Gr hybrid composites. Ultrasonic cavitation assisted stir casting method has been used for fabrication of composites. Al-Si5Cu3 alloy is used as base alloy along with micro sized TiB2 hard ceramic particles (2.5 and 5.5 wt%) as reinforcement and nano-Gr particles (2 and 4 wt%) as solid lubricant additives. SEM micrographs, EDAX spectrum and optical images are considered to observe uniform dispersion of reinforcing phases. Micro-hardness is evaluated using Vicker’s microhardness tester. Hardness is seen to increase with incorporation of TiB2 while the same decreases with incorporation of graphite. Wear and friction of composites are tested for varying load (10 to 40 N) and sliding speed (0.2 to 0.4 m s‑1) using a pin-on-disk tribometer. Worn surfaces are characterized using SEM and EDAX analysis. Wear resistance of composites increases with incorporation of reinforcing phases together. Nano-Gr particles are easily sheared out from the sub-surface and provide a layer over the tribo-surface of composite that enhances friction and wear behavior. Wear mechanism in composites is predominantly adhesion while abrasion and ploughing is prominent in base alloy.

Grained composite materials prepared by combustion synthesis under mechanical pressure

DOEpatents

Dunmead, Stephen D.; Holt, Joseph B.; Kingman, Donald D.; Munir, Zuhair A.

1990-01-01

Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

Computational Thermodynamic Study to Predict Complex Phase Equilibria in the Nickel-Base Superalloy Rene N6

NASA Technical Reports Server (NTRS)

Copland, Evan H.; Jacobson, Nathan S.; Ritzert, Frank J.

2001-01-01

A previous study by Ritzert et al. on the formation and prediction of topologically closed packed (TCP) phases in the nickel-base superalloy Rene' N6 is re-examined with computational thermodynamics. The experimental data on phase distribution in forty-four alloys with a composition within the patent limits of the nickel-base superalloy Rene' N6 provide a good basis for comparison to and validation of a commercial nickel superalloy database used with ThermoCalc. Volume fraction of the phases and partitioning of the elements are determined for the forty-four alloys in this dataset. The baseline heat treatment of 400 h at 1366 K was used. This composition set is particularly interesting since small composition differences lead to dramatic changes in phase composition. In general the calculated values follow the experimental trends. However, the calculations indicated no TCP phase formation when the experimental measurements gave a volume percent of TCP phase less than 2 percent. When TCP phases were predicted, the calculations under-predict the volume percent of TCP phases by a factor of 2 to 8. The calculated compositions of the gamma and gamma' phases show fair agreement with the measurements. However, the calculated compositions of the P Phase do not agree with those measured. This may be due to inaccuracies in the model parameters for P phase and/or issues with the microprobe analyses of these phases. In addition, phase fraction diagrams and sigma and P phase solvus temperatures are calculated for each of the alloys. These calculations indicate that P phase is the primary TCP phase formed for the alloys considered here at 1366 K. Finally, a series of isopleths are calculated for each of the seven alloying elements. These show the effect of each alloying element on creating TCP phases.

Croissance de couches de Si{1-x}Ge{x} par réaction chimique a partir d'une phase gazeuse : étude thermodynamique et analyse du transfert de matière

NASA Astrophysics Data System (ADS)

Rouch, H.; Pons, M.; Bernard, C.; Madar, R.

1995-06-01

The growth of Si{1-x}Gex layers at a high temperature (1300 K) and low pressure (315 Pa) (by chemical vapour deposition) was studied by a thermodynamic approach and a mass transport analysis using simplifying assumptions. The results showed that the thermodynamic analysis does not permit alone to explain the experimental measurements concerning the composition of the layer. The mass transport analysis showed that thermodiffusion would be of importance on layer composition and uniformity for large substrates. La croissance de couches de Si{1-x}Gex à haute température (1300 K) et basse pression (315 Pa) par réaction chimique à partir d'une phase gazeuse a été étudiée à l'aide d'une approche thermodynamique et de l'analyse du transfert de matière pour laquelle des hypothèses très simplificatrices ont été émises. Les résultats ont montré que l'analyse thermodynamique, seule, ne permet pas d'interpréter les mesures concernant la composition du matériau déposé. Quant à l'étude du transfert de matière, elle a montré que la thermodiffusion jouait un rôle important sur la composition du matériau déposé ainsi que sur l'uniformité du dépôt sur des substrats de grandes dimensions.

Crystallization Kinetics of a Solid Oxide Fuel Cell Seal Glass by Differential Thermal Analysis

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Gamble, Eleanor A.

2005-01-01

Crystallization kinetics of a barium calcium aluminosilicate glass (BCAS), a sealant material for planar solid oxide fuel cells, have been investigated by differential thermal analysis (DTA). From variation of DTA peak maximum temperature with heating rate, the activation energy for glass crystallization was calculated to be 259 kJ/mol. Development of crystalline phases on thermal treatments of the glass at various temperatures has been followed by powder x-ray diffraction. Microstructure and chemical composition of the crystalline phases were investigated by scanning electron microscopy and energy dispersive spectroscopic (EDS) analysis. BaSiO3 and hexacelsian (BaAl2Si2O8) were the primary crystalline phases whereas monoclinic celsian (BaAl2Si2O8) and (Ba(x), Ca(y))SiO4 were also detected as minor phases. Needle-shaped BaSiO3 crystals are formed first, followed by the formation of other phases at longer times of heat treatments. The glass does not fully crystallize even after long term heat treatments at 750 to 900 C.

Phase Equilibria Study in the TeO2-Na2O-SiO2 System in Air Between 723 K (500 °C) and 1473 K (1200 °C)

NASA Astrophysics Data System (ADS)

Santoso, Imam; Taskinen, Pekka

2016-08-01

Knowledge of phase equilibria in the TeO2-Na2O-SiO2 system at elevated temperatures is important for ceramic and glass industries and for improving the operation of the smelting process of tellurium-containing materials. A review of previous investigations has indicated, however, that there are omissions in the available datasets on the liquidus temperatures of the molten TeO2-Na2O-SiO2 mixtures. The employed experimental method included equilibration of mixtures made from high purity oxides, rapid quenching of the equilibrated samples in water and followed by compositional analysis of the phases using an electron probe X-ray microanalyzer. The liquidus and phase equilibria in the TeO2-SiO2, TeO2-Na2O, and SiO2-TeO2-Na2O systems have been studied for a wide range of compositions between 723 K (500 °C) and 1473 K (1200 °C) at TeO2, SiO2, and Na2SiO3 saturations. New data have been generated in the SiO2-TeO2-Na2O system at SiO2 saturation. The liquidus compositions in the TeO2-Na2O system at TeO2 saturation have been compared with the previous data and an assessed phase diagram.

Method for preparing polyolefin composites containing a phase change material

DOEpatents

Salyer, Ival O.

1990-01-01

A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein. The composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

Attrition resistant, zinc titanate-containing, reduced sulfur sorbents

DOEpatents

Vierheilig, Albert A.; Gupta, Raghubir P.; Turk, Brian S.

2004-11-02

The disclosure is directed to sorbent compositions for removing reduced sulfur species (e.g., H.sub.2 S, COS and CS.sub.2) a feed stream. The sorbent is formed from a multi-phase composition including a zinc titanate phase and a zinc oxide-aluminate phase. The sorbent composition is substantially free of unreacted alumina.

A silicone rubber based composites using n-octadecane/poly (styrene-methyl methacrylate) microcapsules as energy storage particle

NASA Astrophysics Data System (ADS)

Wu, W. L.; Chen, Z.

A phase-change energy-storage material, silicone rubber (SR) coated n-octadecane/poly (styrene-methyl methacrylate) (SR/OD/P(St-MMA)) microcapsule composites, was prepared by mixing SR and OD/P(St-MMA) microcapsules. The microcapsule content and silicone rubber coated method were investigated. The morphology and thermal properties of the composites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and heat storage properties. The results showed that the thermal and mechanical properties of SR/OD/P(St-MMA) composites were excellent when the microcapsules were coated with room temperature vulcanized silicone rubber (RTVSR), of which content was 2 phr (per hundred rubber). The enthalpy value of the composites was 67.6 J g-1 and the composites were found to have good energy storage function.

Sintering and crystallization behavior of CaMgSi{sub 2}O{sub 6}-NaFeSi{sub 2}O{sub 6} based glass-ceramics

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

Goel, Ashutosh; Kansal, Ishu; Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Facolta di Ingegneria, Universita di Modena e Reggio Emilia, 41100 Modena

2009-11-01

We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi{sub 2}O{sub 6}-10 mol % NaFeSi{sub 2}O{sub 6}. The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850-950more » deg. C in both air and N{sub 2} atmosphere. X-ray diffraction studies adjoined with the Rietveld-reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions.« less

Strain analysis of nanowire interfaces in multiscale composites

NASA Astrophysics Data System (ADS)

Malakooti, Mohammad H.; Zhou, Zhi; Spears, John H.; Shankwitz, Timothy J.; Sodano, Henry A.

2016-04-01

Recently, the reinforcement-matrix interface of fiber reinforced polymers has been modified through grafting nanostructures - particularly carbon nanotubes and ZnO nanowires - on to the fiber surface. This type of interface engineering has made a great impact on the development of multiscale composites that have high stiffness, interfacial strength, toughness, and vibrational damping - qualities that are mutually exclusive to a degree in most raw materials. Although the efficacy of such nanostructured interfaces has been established, the reinforcement mechanisms of these multiscale composites have not been explored. Here, strain transfer across a nanowire interphase is studied in order to gain a heightened understanding of the working principles of physical interface modification and the formation of a functional gradient. This problem is studied using a functionally graded piezoelectric interface composed of vertically aligned lead zirconate titanate nanowires, as their piezoelectric properties can be utilized to precisely control the strain on one side of the interface. The displacement and strain across the nanowire interface is captured using digital image correlation. It is demonstrated that the material gradient created through nanowires cause a smooth strain transfer from reinforcement phase into matrix phase that eliminates the stress concentration between these phases, which have highly mismatched elasticity.

Strain-Detecting Composite Materials

NASA Technical Reports Server (NTRS)

Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

2016-01-01

A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

Modification of carbon composites by nanoceramic compounds

NASA Astrophysics Data System (ADS)

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

2005-06-01

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

Molecular Composition Analysis of Distant Targets

NASA Technical Reports Server (NTRS)

Hughes, Gary B.; Lubin, Philip

2017-01-01

This document is the Final Report for NASA Innovative Advanced Concepts (NIAC) Phase I Grant 15-NIAC16A-0145, titled Molecular Composition Analysis of Distant Targets. The research was focused on developing a system concept for probing the molecular composition of cold solar system targets, such as Asteroids, Comets, Planets and Moons from a distant vantage, for example from a spacecraft that is orbiting the target (Hughes et al., 2015). The orbiting spacecraft is equipped with a high-power laser, which is run by electricity from photovoltaic panels. The laser is directed at a spot on the target. Materials on the surface of the target are heated by the laser beam, and begin to melt and then evaporate, forming a plume of asteroid molecules in front of the heated spot. The heated spot glows, producing blackbody illumination that is visible from the spacecraft, via a path through the evaporated plume. As the blackbody radiation from the heated spot passes through the plume of evaporated material, molecules in the plume absorb radiation in a manner that is specific to the rotational and vibrational characteristics of the specific molecules. A spectrometer aboard the spacecraft is used to observe absorption lines in the blackbody signal. The pattern of absorption can be used to estimate the molecular composition of materials in the plume, which originated on the target. Focusing on a single spot produces a borehole, and shallow subsurface profiling of the targets bulk composition is possible. At the beginning of the Phase I research, the estimated Technology Readiness Level (TRL) of the system was TRL-1. During the Phase I research, an end-to-end theoretical model of the sensor system was developed from first principles. The model includes laser energy and optical propagation, target heating, melting and evaporation of target material, plume density, thermal radiation from the heated spot, molecular cross section of likely asteroid materials, and estimation of the absorption profile at a distant spectrometer. Results obtained by executing simulations based on the model provide compelling evidence that the concept of remote laser evaporative molecular absorption spectroscopy is feasible. In this document, technical details of the model are presented, and results of simulations are described that indicate the utility of the proposed sensor system. Additionally, an asteroid rendezvous mission is analyzed, with a survey of system requirements to accomplish molecular composition analysis of the asteroid. Based on positive theoretical results obtained during Phase I, the estimated TRL of the system is now TRL-2. This document also describes potential future research and experimentation that could push the system to TRL-4 within 2 years. Steps required for construction of a laboratory prototype are described. An experiment to test predictions of the theory is described, based on the laboratory prototype setup.

Phase-Separated Polyaniline/Graphene Composite Electrodes for High-Rate Electrochemical Supercapacitors.

PubMed

Wu, Jifeng; Zhang, Qin'e; Zhou, An'an; Huang, Zhifeng; Bai, Hua; Li, Lei

2016-12-01

Polyaniline/graphene hydrogel composites with a macroscopically phase-separated structure are prepared. The composites show high specific capacitance and excellent rate performance. Further investigation demonstrates that polyaniline inside the graphene hydrogel has low rate performance, thus a phase-separated structure, in which polyaniline is mainly outside the graphene hydrogel matrix, can enhance the rate performance of the composites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characteristics Associated with the Madden-Julian Oscillation at Manus Island

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

Deng, Liping; McFarlane, Sally A.; Flaherty, Julia E.

2013-05-15

Ground-based high temporal and vertical resolution datasets from 2002 to 2008 of observations at the Atmospheric Radiation Measurement (ARM) Tropical Western Pacific (TWP) site on Manus Island, Papua New Guinea are used to examine the evolution of clouds and rainfall associated with the MJO life cycle. A composite MJO event is developed based on the NOAA MJO Index 4 using 13 events. The analysis shows that the cloud evolution during the composited MJO life cycle depicts a two-phase structure consisting of a development phase and a mature phase. During the development phase, congestus is the most important cloud type; duringmore » the mature phase, deep convection is the dominant cloud type. Consistent with this two-phase structure, the heavy rainfall frequency also shows a two-peak structure during the MJO life cycle. Light rainfall does not show a clear relation to the MJO life cycle, but shows variability on shorter time scales. From the development phase to the mature phase, the MJO structure shifts from the Type I to Type II structure, showing a different phase relationship between convection and dynamic fields (or wave motion) in the development and mature phases. During the shift, mid-level clouds play an important role in moving moisture to the mid-troposphere and preparing the atmosphere for the following deep convection. The discharge-recharge theory explains some of observed features of the MJO evolution at the ARM TWP Manus Island site.« less

Ultra-soft magnetic properties and correlated phase analysis by {sup 57}Fe Mössbauer spectroscopy of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} alloy

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

Manjura Hoque, S.; Liba, S. I.; Akhter, Shireen

2016-02-15

A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si) soft nano composites. Bright (BF) and dark fieldmore » (DF) image with selective area diffraction (SAD) patterns by the transmission electron microscopy (TEM) of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si) phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD), and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.« less

Ultra-soft magnetic properties and correlated phase analysis by 57Fe Mössbauer spectroscopy of Fe74Cu0.8Nb2.7Si15.5B7 alloy

NASA Astrophysics Data System (ADS)

Manjura Hoque, S.; Liba, S. I.; Anirban, A.; Choudhury, Shamima; Akhter, Shireen

2016-02-01

A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe74Cu0.8Nb2.7Si15.5B7 was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si) soft nano composites. Bright (BF) and dark field (DF) image with selective area diffraction (SAD) patterns by the transmission electron microscopy (TEM) of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si) phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD), and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.

Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

DOEpatents

Podtburg, E.R.

1999-06-22

An oxide superconductor composite having improved texture and durability is disclosed. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor. 1 fig.

Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

DOEpatents

Podtburg, Eric R.

1999-01-01

An oxide superconductor composite having improved texture and durability. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor.

RELIABLE COMPUTATION OF HOMOGENEOUS AZEOTROPES. (R824731)

EPA Science Inventory

Abstract

It is important to determine the existence and composition of homogeneous azeotropes in the analysis of phase behavior and in the synthesis and design of separation systems, from both theoretical and practical standpoints. A new method for reliably locating an...

Effects of synthesis techniques on chemical composition, microstructure and dielectric properties of Mg-doped calcium titanate

NASA Astrophysics Data System (ADS)

Jongprateep, Oratai; Sato, Nicha

2018-04-01

Calcium titanate (CaTiO3) has been recognized as a material for fabrication of dielectric components, owing to its moderate dielectric constant and excellent microwave response. Enhancement of dielectric properties of the material can be achieved through doping, compositional and microstructural control. This study, therefore, aimed at investigating effects of powder synthesis techniques on compositions, microstructure, and dielectric properties of Mg-doped CaTiO3. Solution combustion and solid-state reaction were powder synthesis techniques employed in preparation of undoped CaTiO3 and CaTiO3 doped with 5-20 at% Mg. Compositional analysis revealed that powder synthesis techniques did not exhibit a significant effect on formation of secondary phases. When Mg concentration did not exceed 5 at%, the powders prepared by both techniques contained only a single phase. An increase of MgO secondary phase was observed as Mg concentrations increased from 10 to 20 at%. Experimental results, on the contrary, revealed that powder synthesis techniques contributed to significant differences in microstructure. Solution combustion technique produced powders with finer particle sizes, which consequently led to finer grain sizes and density enhancement. High-density specimens with fine microstructure generally exhibit improved dielectric properties. Dielectric measurements revealed that dielectric constants of all samples ranged between 231 and 327 at 1 MHz, and that superior dielectric constants were observed in samples prepared by the solution combustion technique.

Two-dimensional bismuth-rich nanosheets through the evaporative thinning of Se-doped Bi2Te3

NASA Astrophysics Data System (ADS)

Hanson, Eve D.; Shi, Fengyuan; Chasapis, Thomas C.; Kanatzidis, Mercouri G.; Dravid, Vinayak P.

2016-02-01

High bulk conductance obscures the behavior of surface states in the prototypical topological insulators Bi2Te3 and Bi2Se3. However, ternary phases of Bi2Te3-ySey with balanced donor and acceptor levels may lead to large bulk resistivity, allowing for the observation of the surface states. Additionally, the contribution of the bulk conductance may be further suppressed by nanostructuring, increasing the surface-to-volume ratio. Herein we report the synthesis of a ternary tetradymite newly confined to two dimensions. Ultra-thin large-area stable nanosheets were fabricated via evaporative thinning of a Bi2Te2.9Se0.1 original phase. Owing to vapor pressure differences, a compositional shift to a final Bi-rich phase is observed. The Se/Te ratio of the nanosheet increases tenfold, due to the higher stability of the Bi-Se bonds. Hexagonal crystal symmetry is maintained despite dramatic changes in thickness and stoichiometry. Given that small variations in stoichiometry of this ternary system can incur large changes in carrier concentration and switch majority carrier type, the large compositional shifts found in this case imply that compositional analysis of similar CVD and PVD grown materials is critical to correctly interpret topological insulator performance. Further, the characterization techniques deployed, including STEM-EDS and ToF-SIMS, serve as a case study in determining such compositional shifts in two-dimensional form.

Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

PubMed

Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

2016-04-15

Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical simulation of submicron particles formation by condensation at coals burning

NASA Astrophysics Data System (ADS)

Kortsenshteyn, N. M.; Petrov, L. V.

2017-11-01

The thermodynamic analysis of the composition of the combustion products of 15 types of coals was carried out with consideration for the formation of potassium and sodium aluminosilicates and solid and liquid slag removal. Based on the results of the analysis, the approximating temperature dependences of the concentrations of condensed components (potassium and sodium sulfates) were obtained for the cases of two-phase and single-phase equilibriums; conclusions on the comparative influence of solid and liquid slag removal on the probability of the formation of submicron particles on the combustion of coals were made. The found dependences was make it possible to perform a numerical simulation of the bulk condensation of potassium and sodium sulfate vapors upon the cooling of coal combustion products in a process flow. The number concentration and size distribution of the formed particles have been determined. Agreement with experimental data on the fraction composition of particles has been reached at a reasonable value of a free parameter of the model.

Effect Of Chromium Underlayer On The Properties Of Nano-Crystalline Diamond Films

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

Garratt, Elias; AlFaify, Salem; Yoshitake, T.

2013-01-11

This paper investigated the effect of chromium underlayer on the structure, microstructure and composition of the nano-crystalline diamond films. Nano-crystalline diamond thin films were deposited at high temperature in microwave-induced plasma diluted with nitrogen, on silicon substrate with a thin film of chromium as an underlayer. The composition, structure and microstructure of the deposited layers were analyzed using non-Rutherford Backscattering Spectrometry, Raman Spectroscopy, Near-Edge X-Ray Absorption Fine Structure, X-ray Diffraction and Atomic Force Microscopy. Nanoindentation studies showed that the films deposited on chromium underlayer have higher hardness values compared to those deposited on silicon without an underlayer. Diamond and graphiticmore » phases of the films evaluated by x-ray and optical spectroscopic analysis determined consistency between sp2 and sp3 phases of carbon in chromium sample to that of diamond grown on silicon. Diffusion of chromium was observed using ion beam analysis which was correlated with the formation of chromium complexes by x-ray diffraction.« less

Evidence of phase transition in Nd3+ doped phosphate glass determined by thermal lens spectrometry.

PubMed

Andrade, Acácio A; Lourenço, Sidney A; Pilla, Viviane; Silva, Anielle C Almeida; Dantas, Noelio O

2014-01-28

Thermal lens spectroscopy (TLS), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) techniques were applied to the thermo-optical property analysis of a new phosphate glass matrix PANK with nominal composition 40P2O5·20Al2O3·35Na2O·5K2O (mol%), doped with different Nd(3+) compositions. This glass system, synthesized by the fusion protocol, presents high transparency from UV to the near infrared, excellent thermo-optical properties at room temperature and high fluorescence quantum efficiency. Thermal lens phase shift parameters, thermal diffusivity and the DSC signal present pronounced changes at about 61 °C for the PANK glass system. This anomalous behavior was associated with a phase transition in the nanostructured glass materials. The FTIR signal confirms the presence of isolated PO4 tetrahedron groups connected to different cations in PANK glass. As a main result, our experimental data suggest that these tetrahedron groups present a structural phase transition, paraelectric-ferroelectric phase transition, similar to that in potassium dihydrogen phosphate, KH2PO4, nanocrystals and which TLS technique can be used as a sensitive method to investigate changes in the structural level of nanostructured materials.

Calcium titanium silicate based glass-ceramic for nuclear waste immobilisation

NASA Astrophysics Data System (ADS)

Sharma, K.; Srivastav, A. P.; Goswami, M.; Krishnan, Madangopal

2018-04-01

Titanate based ceramics (synroc) have been studied for immobilisation of nuclear wastes due to their high radiation and thermal stability. The aim of this study is to synthesis glass-ceramic with stable phases from alumino silicate glass composition and study the loading behavior of actinides in glass-ceramics. The effects of CaO and TiO2 addition on phase evolution and structural properties of alumino silicate based glasses with nominal composition x(10CaO-9TiO2)-y(10Na2O-5 Al2O3-56SiO2-10B2O3); where z = x/y = 1.4-1.8 are reported. The glasses are prepared by melt-quench technique and characterized for thermal and structural properties using DTA and Raman Spectroscopy. Glass transition and peak crystallization temperatures decrease with increase of CaO and TiO2 content, which implies the weakening of glass network and increased tendency of glasses towards crystallization. Sphene (CaTiSiO5) and perovskite (CaTiO3) crystalline phases are confirmed from XRD which are well known stable phase for conditioning of actinides. The microsturcture and elemental analysis indicate the presence of actinide in stable crystalline phases.

Metallurgical and electrochemical characterization of contemporary silver-based soldering alloys.

PubMed

Ntasi, Argyro; Al Jabbari, Youssef; Mueller, Wolf Dieter; Eliades, George; Zinelis, Spiros

2014-05-01

To investigate the microstructure, hardness, and electrochemical behavior of four contemporary Ag-based soldering alloys used for manufacturing orthodontic appliances. The Ag-based alloys tested were Dentaurum Universal Silver Solder (DEN), Orthodontic Solders (LEO), Ortho Dental Universal Solder (NOB), and Silver Solder (ORT). Five disk-shaped specimens were produced for each alloy, and after metallographic preparation their microstructural features, elemental composition, and hardness were determined by scanning electron microscopy with energy-dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD) analysis, and Vickers hardness testing. The electrochemical properties were evaluated by anodic potentiodynamic scanning in 0.9% NaCl and Ringer's solutions. Hardness, corrosion current (Icorr), and corrosion potential (Ecorr) were statistically analyzed by one-way analysis of variance and Tukey test (α=.05). EDX analysis showed that all materials belong to the Ag-Zn-Cu ternary system. Three different mean atomic contrast phases were identified for LEO and ORT and two for DEN and NOB. According to XRD analysis, all materials consisted of Ag-rich and Cu-rich face-centered cubic phases. Hardness testing classified the materials in descending order as follows: DEN, 155±3; NOB, 149±3; ORT, 141±4; and LEO, 136±8. Significant differences were found for Icorr of NOB in Ringer's solution and Ecorr of DEN in 0.9% NaCl solution. Ag-based soldering alloys demonstrate great diversity in their elemental composition, phase size and distribution, hardness, and electrochemical properties. These differences may anticipate variations in their clinical performance.

Effect of rolling on phase composition and microhardness of austenitic steels with different stacking-fault energies

NASA Astrophysics Data System (ADS)

Melnikov, Eugene; Astafurova, Elena; Maier, Galina; Moskvina, Valentina

2017-12-01

The influence of multi-pass cold rolling on the phase composition and microhardness of austenitic Fe-18Cr-9Ni-0.21C, Fe-18Cr-9Ni-0.5Ti-0.08C, Fe-17Cr-13Ni-3Mo-0.01C (in wt %) steels with different stacking fault energies was studied. The metastable Fe-18Cr-9Ni-0.5Ti-0.08C steel undergoes γ → α' phase transformations during rolling, the volume fraction of strain-induced α'-martensite in steel structure is increased with increasing strain. Metastable austenite Fe-18Cr-9Ni-0.21C steel does not undergo the formation of an appreciable amount of strain-induced α'-martensite under rolling, but the magnetophase analysis reveals a small amount of ferrite phase in the structure of steel after rolling. The structure of stable Fe-17Cr-13Ni-3Mo-0.01C steel remains austenitic independently under strain. Investigations of microhardness of the steels show that their values are increased with strain and are dependent on propensity of steels to strain-induced martensitic transformation.

Thermoelectric Transport Signatures of Dirac Composite Fermions in the Half-Filled Landau Level

NASA Astrophysics Data System (ADS)

Potter, Andrew C.; Serbyn, Maksym; Vishwanath, Ashvin

2016-07-01

The half-filled Landau level is expected to be approximately particle-hole symmetric, which requires an extension of the Halperin-Lee-Read (HLR) theory of the compressible state observed at this filling. Recent work indicates that, when particle-hole symmetry is preserved, the composite fermions experience a quantized π -Berry phase upon winding around the composite Fermi surface, analogous to Dirac fermions at the surface of a 3D topological insulator. In contrast, the effective low-energy theory of the composite fermion liquid originally proposed by HLR lacks particle-hole symmetry and has vanishing Berry phase. In this paper, we explain how thermoelectric transport measurements can be used to test the Dirac nature of the composite fermions by quantitatively extracting this Berry phase. First, we point out that longitudinal thermopower (Seebeck effect) is nonvanishing because of the unusual nature of particle-hole symmetry in this context and is not sensitive to the Berry phase. In contrast, we find that off-diagonal thermopower (Nernst effect) is directly related to the topological structure of the composite Fermi surface, vanishing for zero Berry phase and taking its maximal value for π Berry phase. In contrast, in purely electrical transport signatures, the Berry phase contributions appear as small corrections to a large background signal, making the Nernst effect a promising diagnostic of the Dirac nature of composite fermions.

Simple views on critical binary liquid mixtures in porous glass

NASA Astrophysics Data System (ADS)

Tremblay, L.; Socol, S. M.; Lacelle, S.

2000-01-01

A simple scenario, different from previous attempts, is proposed to resolve the problem of the slow phase separation dynamics of binary liquid mixtures confined in porous Vycor glass. We demonstrate that simply mutual diffusion, renormalized by critical composition fluctuations and geometrical hindrance of the porous glass, accounts for the slow phase separation kinetics. Capillary invasion studies of porous Vycor glass by the critical isobutyric acid-water mixture, close to the consolute solution temperature, corroborate our analysis.

The effect of surfactants on epitaxial growth of gallium nitride from gas phase in the Ga-HCl-NH3-H2-Ar system

NASA Astrophysics Data System (ADS)

Zhilyaev, Yu. V.; Zelenin, V. V.; Orlova, T. A.; Panteleev, V. N.; Poletaev, N. K.; Rodin, S. N.; Snytkina, S. A.

2015-05-01

We have studied epitaxial layers of gallium nitride (GaN) in a template composition grown by surfactant-mediated hydride-chloride vapor phase epitaxy. The surfactant component was provided by 5 mass % additives of antimony and indium to the source of gallium. Comparative analysis of the obtained results shows evidence of the positive influence of surfactants on the morphology of epitaxial GaN layers.

Application of Finite Element, Phase-field, and CALPHAD-based Methods to Additive Manufacturing of Ni-based Superalloys.

PubMed

Keller, Trevor; Lindwall, Greta; Ghosh, Supriyo; Ma, Li; Lane, Brandon M; Zhang, Fan; Kattner, Ursula R; Lass, Eric A; Heigel, Jarred C; Idell, Yaakov; Williams, Maureen E; Allen, Andrew J; Guyer, Jonathan E; Levine, Lyle E

2017-10-15

Numerical simulations are used in this work to investigate aspects of microstructure and microseg-regation during rapid solidification of a Ni-based superalloy in a laser powder bed fusion additive manufacturing process. Thermal modeling by finite element analysis simulates the laser melt pool, with surface temperatures in agreement with in situ thermographic measurements on Inconel 625. Geometric and thermal features of the simulated melt pools are extracted and used in subsequent mesoscale simulations. Solidification in the melt pool is simulated on two length scales. For the multicomponent alloy Inconel 625, microsegregation between dendrite arms is calculated using the Scheil-Gulliver solidification model and DICTRA software. Phase-field simulations, using Ni-Nb as a binary analogue to Inconel 625, produced microstructures with primary cellular/dendritic arm spacings in agreement with measured spacings in experimentally observed microstructures and a lesser extent of microsegregation than predicted by DICTRA simulations. The composition profiles are used to compare thermodynamic driving forces for nucleation against experimentally observed precipitates identified by electron and X-ray diffraction analyses. Our analysis lists the precipitates that may form from FCC phase of enriched interdendritic compositions and compares these against experimentally observed phases from 1 h heat treatments at two temperatures: stress relief at 1143 K (870 °C) or homogenization at 1423 K (1150 °C).

Liquid chromatography-diode array detection-mass spectrometry for compositional analysis of low molecular weight heparins.

PubMed

Wang, Zhangjie; Li, Daoyuan; Sun, Xiaojun; Bai, Xue; Jin, Lan; Chi, Lianli

2014-04-15

Low molecular weight heparins (LMWHs) are important artificial preparations from heparin polysaccharide and are widely used as anticoagulant drugs. To analyze the structure and composition of LMWHs, identification and quantitation of their natural and modified building blocks are indispensable. We have established a novel reversed-phase high-performance liquid chromatography-diode array detection-electrospray ionization-mass spectrometry approach for compositional analysis of LMWHs. After being exhaustively digested and labeled with 2-aminoacridone, the structural motifs constructing LMWHs, including 17 components from dalteparin and 15 components from enoxaparin, were well separated, identified, and quantified. Besides the eight natural heparin disaccharides, many characteristic structures from dalteparin and enoxaparin, such as modified structures from the reducing end and nonreducing end, 3-O-sulfated tetrasaccharides, and trisaccharides, have been unambiguously identified based on their retention time and mass spectra. Compared with the traditional heparin compositional analysis methods, the approach described here is not only robust but also comprehensive because it is capable of identifying and quantifying nearly all components from lyase digests of LMWHs. Copyright © 2014 Elsevier Inc. All rights reserved.

Polyolefin composites containing a phase change material

DOEpatents

Salyer, Ival O.

1991-01-01

A composite useful in thermal energy storage, said composite being formed of a polyolefin matrix having a phase change material such as a crystalline alkyl hydrocarbon incorporated therein, said polyolefin being thermally form stable; the composite is useful in forming pellets, sheets or fibers having thermal energy storage characteristics; methods for forming the composite are also disclosed.

Analysis of the Glass-Forming Ability of Fe-Er Alloys, Based on Thermodynamic Modeling

NASA Astrophysics Data System (ADS)

Arutyunyan, N. A.; Zaitsev, A. I.; Dunaev, S. F.; Kalmykov, K. B.; El'nyakov, D. D.; Shaposhnikov, N. G.

2018-05-01

The Fe-Er phase diagram and thermodynamic properties of all its phases are assessed by means of self-consistent analysis. To refine the data on phase equilibria in the Fe-Er system, an investigation is performed in the 10-40 at % range of Er concentrations. The temperature-concentration dependences of the thermodynamic properties of a melt are presented using the model of ideal associated solutions. Thermodynamic parameters of each phase are obtained, and the calculated results are in agreement with available experimental data. The correlation between the thermodynamic properties of liquid Fe-Er alloys and their tendency toward amorphization are studied. It is shown that compositions of amorphous alloys prepared by melt quenching coincide with the ranges of concentration with the predominance of Fe3Er and FeEr2 associative groups that have large negative entropies of formation.

RuO2/Activated Carbon Composite Electrode Prepared by Modified Colloidal Procedure and Thermal Decomposition Method

NASA Astrophysics Data System (ADS)

Li, Xiang; Zheng, Feng; Gan, Weiping; Luo, Xun

2016-01-01

RuO2/activated carbon (AC) composite electrode was prepared by a modified colloidal procedure and a thermal decomposition method. The precursor for RuO2/AC was coated on tantalum sheet and annealed at 150°C to 190°C for 3 h to develop thin-film electrode. The microstructure and morphology of the RuO2/AC film were characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The TGA results showed the maximum loss of RuO2/AC composite film at 410°C, with residual RuO2 of 23.17 wt.%. The amorphous phase structure of the composite was verified by XRD analysis. SEM analysis revealed that fine RuO2 particles were dispersed in an activated carbon matrix after annealing. The electrochemical properties of RuO2/AC electrode were examined by cycling voltammetry, galvanostatic charge-discharge, and cyclic behavior measurements. The specific capacitance of RuO2/AC electrode reached 245 F g-1. The cyclic behavior of RuO2/AC electrode was stable. Optimal annealing was achieved at 170°C for 3 h.

Aromatherapy: composition of the gaseous phase at equilibrium with liquid bergamot essential oil.

PubMed

Leggio, Antonella; Leotta, Vanessa; Belsito, Emilia Lucia; Di Gioia, Maria Luisa; Romio, Emanuela; Santoro, Ilaria; Taverna, Domenico; Sindona, Giovanni; Liguori, Angelo

2017-11-02

This work compares the composition at different temperatures of gaseous phase of bergamot essential oil at equilibrium with the liquid phase. A new GC-MS methodology to determine quantitatively the volatile aroma compounds was developed. The adopted methodology involved the direct injection of headspace gas into injection port of GC-MS system and of known amounts of the corresponding authentic volatile compounds. The methodology was validated. This study showed that gaseous phase composition is different from that of the liquid phase at equilibrium with it.

Condensed phase conversion and growth of nanorods instead of from vapor

DOEpatents

Geohegan, David B.; Seals, Roland D.; Puretzky, Alex A.; Fan, Xudong

2005-08-02

Compositions, systems and methods are described for condensed phase conversion and growth of nanorods and other materials. A method includes providing a condensed phase matrix material; and activating the condensed phase matrix material to produce a plurality of nanorods by condensed phase conversion and growth from the condensed chase matrix material instead of from vacor. The compositions are very strong. The compositions and methods provide advantages because they allow (1) formation rates of nanostructures necessary for reasonable production rates, and (2) the near net shaped production of component structures.

Development of Cu Reinforced SiC Particulate Composites

NASA Astrophysics Data System (ADS)

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

2015-02-01

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

Technology development for phosphoric acid fuel cell powerplant, phase 2

NASA Technical Reports Server (NTRS)

Christner, L.

1979-01-01

A technique for producing an acid inventory control member by spraying FEP onto a partially screened carbon paper backing is discussed. Theoretical analysis of the acid management indicates that the vapor composition of 103% H3PO4 is approximately 1.0 ppm P4O10. An SEM evaluation of corrosion resistance of phenolic resins and graphite/phenolic resin composites in H3PO4 at 185 C shows specific surface etching. Carbonization of graphite/phenolic bipolar plates is achieved without blistering.

Analysis of x-ray diffraction pattern and complex plane impedance plot of polypyrrole/titanium dioxide nanocomposite: A simulation study

NASA Astrophysics Data System (ADS)

Ravikiran, Y. T.; Vijaya Kumari, S. C.

2013-06-01

To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.

Fibrillar Organic Phases And Their Roles In Rigid Biological Composites

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

Arey, Bruce W.; Park, John J.; Mayer, George

2015-06-01

This study focused on determining the presence of organic phases in the siliceous components of rigid marine composites ("glass" sponge spicules), and thereby to clarify how those composites dissipate significant mechanical energy. Through the use of imaging by helium ion microscopy in the examination of the spicules, the organic phase that is present between the layers of hydrated silica was also detected within the silica cylinders of the composite, indicating the existence therein of a network, scaffolding, or other pattern that has not yet been determined. It was concluded that the presence of an interpenetrating network of some kind, andmore » tenacious fibrillar interfaces are responsible for the large energy dissipation in these siliceous composites by viscoelastic processes. This discovery means that future mechanics analyses of such composites, extending to large deformations must consider such interpenetrating phases.« less

Bioelectrical Impedance Phase Angle as an Indicator of Malnutrition in Hospitalized Children with Diagnosed Inflammatory Bowel Diseases-A Case Control Study.

PubMed

Więch, Paweł; Dąbrowski, Mariusz; Bazaliński, Dariusz; Sałacińska, Izabela; Korczowski, Bartosz; Binkowska-Bury, Monika

2018-04-17

The phase angle (PhA) seems to be a reliable screening tool for the identification of malnutrition risk in hospitalized children with inflammatory bowel disease (IBD). The aim of the present study was to assess the body composition and nutritional status of hospitalized children and adolescents with IBD by using bioelectrical impedance analysis (BIA) with phase angle (PhA) calculation, which has not been evaluated in hospitalized children with IBD yet. A total of 59 children and adolescents aged 4–18 years, with IBD: 34 ulcerative colitis (UC) and 25 Crohn’s disease (CD) were included in the study. The control group consisted of healthy children and adolescents, strictly matched for gender and age in a 1:1 case-control manner. In both groups, BIA was performed and PhA was calculated. IBD patients had significantly lower PhA (UC: 5.34 ± 1.34 vs. 5.96 ± 0.76, p = 0.040; CD: 5.16 ± 1.18 vs. 5.90 ± 0.62, p = 0.009) compared to the control subjects. Significant changes in selected body composition parameters were observed particularly in CD, especially in fat free mass components. Lower phase angle score together with lower body composition parameters and selected nutrition indicators in children and adolescents with IBD demonstrate their worse nutritional and functional status compared to healthy subjects.

Mineral composition of lunar late mare volcanism revealed from Kaguya SP data

NASA Astrophysics Data System (ADS)

Kato, S.; Morota, T.; Yamaguchi, Y.; Watanabe, S.; Otake, H.; Ohtake, M.; Nimura, T.

2017-12-01

Lunar mare basalts provide insights into the composition and thermal history of the lunar mantle. According to previous studies of crater counting analysis using remote sensing data, the ages of mare basalts suggest a first peak of magma activity at 3.2-3.8 Ga and a second peak at 2 Ga. To understand the mechanism for causing the second peak and its magma source is essential to constrain the thermal history of the lunar mantle. In our previous study [Kato et al., 2017], we reassess the correlation between the titanium contents and the eruption ages of mare basalt units using the compositional and chronological data updated by SELENE (Kaguya). The results show a rapid increase in mean titanium content near 2.3 Ga in the Procellarum KREEP Terrane (PKT), where the latest eruptions are concentrated. Moreover, the high-titanium basaltic eruptions are correlated with the second peak in volcanic activity at 2 Ga. Here we designate volcanisms before and after 2.3 Ga as Phase-1 and Phase-2 volcanism. To understand the mechanism of Phase-2 mare volcanism and its magma source, determining the mineral components and elemental compositions of mare basalts in the PKT is important. Nimura [2011] improved the modified Gaussian model (MGM) [Sunshine et al., 1990] by obtaining the relations between chemical compositions of minerals (the ratio of Fe/(Fe+Mg) in olivine and the ratios of Ca/(Ca+Fe+Mg) and Fe/(Ca+Fe+Mg) in pyroxene) and absorption band parameters (center, width and strength ratio of Gaussian curves). In this study, we re-derived the relations using experimental spectral data and applied the method to spectral data of mare basalts obtained by Kaguya Spectral Profiler (SP) to estimate the mineral components and elemental compositions of lunar mare basalts.

Microstructural analyses of two high noble gold-platinum alloys before and after conditioning in a cell culture medium

NASA Astrophysics Data System (ADS)

Rudolf, R.; Anzel, I.; Gusel, L.; Stamenkovi, D.; Todorovi, A.; Colic, M.

2010-12-01

Microstructures of two high noble experimental Au-Pt alloys were compared before and after conditioning for biocompatibility, in order to identify phases and microelements responsible for the alloys' corrosive behaviour. Microstructural characterization was carried-out by optical and scanning electron microscopy, in addition to energy dispersive X-ray analysis. X-ray diffraction was applied to determine the phases' composition and their contribution in the alloys. Additionally, simultaneous thermal analysis was used to identify the temperatures of phase transformations. An overall assessment before conditioning showed that Au-Pt I is a two-phase alloy containing a dominant Au-rich α1 phase and a minor Pt-rich α2 phase, while the Au-Pt II alloy contains in addition three minor phases: AuZn3, Pt3Zn and Au1.4Zn0.52. The highest content of Zn (up to 6.76 wt.%) was detected in the Pt3Zn phase. After RPMI cell culture medium conditioning, the Pt3Zn and AuZn3 phases disappeared, suggesting that they are predominantly responsible for Zn loss and the lower corrosive stability of the Au-Pt II alloy.

Hollow porous ionic liquids composite polymers based solid phase extraction coupled online with high performance liquid chromatography for selective analysis of hydrophilic hydroxybenzoic acids from complex samples.

PubMed

Dai, Xingping; Wang, Dongsheng; Li, Hui; Chen, Yanyi; Gong, Zhicheng; Xiang, Haiyan; Shi, Shuyun; Chen, Xiaoqing

2017-02-10

Polar and hydrophilic properties of hydroxybenzoic acids usually made them coelute with interferences in high performance liquid chromatography (HPLC) analysis. Then selective analysis of them was necessary. Herein, hollow porous ionic liquids composite polymers (PILs) based solid phase extraction (SPE) was firstly fabricated and coupled online with HPLC for selective analysis of hydroxybenzoic acids from complex matrices. Hollow porous PILs were firstly synthesized using Mobil Composition of Matter No. 48 (MCM-48) spheres as sacrificial support, 1-vinyl-3-methylimidazolium chloride (VMIM + Cl - ) as monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Various parameters affecting synthesis, adsorption and desorption behaviors were investigated and optimized. Steady-state adsorption studies showed the resulting hollow porous PILs exhibited high adsorption capacity, fast adsorption kinetics, and excellent specific adsorption. Subsequently, the application of online SPE system was studied by selective analysis of protocatechuic acid (PCA), 4-hydroxybenzoic acid (4-HBA), and vanillic acid (VA) from Pollen Typha angustifolia. The obtained limit of detection (LOD) varied from 0.002 to 0.01μg/mL, the linear range (0.05-5.0μg/mL) was wide with correlation coefficient (R) from 0.9982 to 0.9994, and the average recoveries at three spiking levels ranged from 82.7 to 102.4%, with column-to-column relative standard deviation (RSD) below 8.1%. The proposed online method showed good accuracy, precision, specificity and convenience, which opened up a universal and efficient route for selective analysis of hydroxybenzoic acids from complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Boron-carbide-aluminum and boron-carbide-reactive metal cermets

DOEpatents

Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

1986-01-01

Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

Boron-carbide-aluminum and boron-carbide-reactive metal cermets. [B/sub 4/C-Al

DOEpatents

Halverson, D.C.; Pyzik, A.J.; Aksay, I.A.

1985-05-06

Hard, tough, lighweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidated step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modules of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi..sqrt..in. These composites and methods can be used to form a variety of structural elements.

Adjustability of resonance frequency by external magnetic field and bias electric field of sandwich magnetoelectric PZT/NFO/PZT composites

NASA Astrophysics Data System (ADS)

Xu, Ling-Fang; Feng, Xing; Sun, Kang; Liang, Ze-Yu; Xu, Qian; Liang, Jia-Yu; Yang, Chang-Ping

2017-07-01

Sandwich magnetoelectric composites of PZT/NFO/PZT (PNP) have been prepared by laminating PZT5, NiFe2O4, and PZT5 ceramics in turn with polyvinyl alcohol (PVA) paste. A systematic study of structural, magnetic and ferroelectric properties is undertaken. Structural studies carried out by X-ray diffraction indicate formation of cubic perovskite phase of PZT5 ceramic and cubic spinel phase of NiFe2O4 ceramic. As increasing the content of PZT5 phase, ferroelectric loops and magnetic loops of PNP composites showed increasing remnant electric polarizations and decreasing remnant magnetic moments separately. Both external magnetic fields and bias voltages could regulate the basal radial resonance frequency of the composites, which should be originated with the transformation and coupling of the stress between the piezoelectric phase and magnetostrictive phase. Such magnetoelectric composite provides great opportunities for electrostatically tunable devices.

Mechanical behavior of glass/epoxy composite laminate with varying amount of MWCNTs under different loadings

NASA Astrophysics Data System (ADS)

Singh, K. K.; Rawat, Prashant

2018-05-01

This paper investigates the mechanical response of three phased (glass/MWCNTs/epoxy) composite laminate under three different loadings. Flexural strength, short beam strength and low-velocity impact (LVI) testing are performed to find an optimum doping percentage value for maximum enhancement in mechanical properties. In this work, MWCNTs were used as secondary reinforcement for three-phased composite plate. MWCNT doping was done in a range of 0–4 wt% of the thermosetting matrix system. Symmetrical design eight layered glass/epoxy laminate with zero bending extension coupling laminate was fabricated using a hybrid method i.e. hand lay-up technique followed by vacuum bagging method. Ranging analysis of MWCNT mixing highlighted the enhancement in flexural, short beam strength and improvement in damage tolerance under LVI loading. While at higher doping wt%, agglomeration of MWCNTs are observed. Results of mechanical testing proposed an optimized doping value for maximum strength and damage resistance of the laminate.

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

Coughanowr, C.A.

The electrochemical machining (ECM) of a cemented titanium carbide/10% nickel composite has been investigated and compared to the ECM of the pure components, TiC and Ni. All three materials were machined in 2M KNO/sub 3/ electrolyte, under current densities ranging from 17 to 100 A/cm/sup 2/. The ECM behavior of the TiC/Ni composite was found to be intermediate to that of its components. The apparent valences of dissolution for all three materials were independent of current density in the range studied: 2.8 eq/gmol for Ni, and 6.6 and 6.5 eq/gmol for TiC and TiC/Ni, respectively. Linear cell voltage versus currentmore » density relationships were obtained for all three materials. Surface analysis of the TiC/Ni composite showed preferential dissolution of the TiC phase over the nickel phase for the entire range of operating conditions investigated. A polishing regime could not be identified for cemented TiC/Ni.« less

Strain-induced nanostructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 on SrTiO3 epitaxial thin films with low PbTiO3 concentration

NASA Astrophysics Data System (ADS)

Kiguchi, Takanori; Fan, Cangyu; Shiraishi, Takahisa; Konno, Toyohiko J.

2017-10-01

The singularity of the structure in (1 - x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) (x = 0-50 mol %) epitaxial thin films of 100 nm thickness was investigated from the viewpoint of the localized residual strain in the nanoscale. The films were deposited on SrTiO3 (STO) (001) single-crystal substrates by chemical solution deposition (CSD) using metallo-organic decomposition (MOD) solutions. X-ray and electron diffraction patterns revealed that PMN-xPT thin films included a single phase of the perovskite-type structure with the cube-on-cube orientation relationship between PMN-xPT and STO: (001)Film ∥ (001)Sub, [100]Film ∥ [100]Sub. X-ray reciprocal space maps showed an in-plane tensile strain in all the compositional ranges considered. Unit cells in the films were strained from the rhombohedral (pseudocubic) (R) phase to a lower symmetry crystal system, the monoclinic (MB) phase. The morphotropic phase boundary (MPB) that split the R and tetragonal (T) phases was observed at x = 30-35 for bulk crystals of PMN-xPT, whereas the strain suppressed the transformation from the R phase to the T phase in the films up to x = 50. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) analysis and its related local strain analysis revealed that all of the films have a bilayer morphology. The nanoscale strained layer formed only above the film/substrate semi-coherent interface. The misfit dislocations generated the localized and periodic strain fields deformed the unit cells between the dislocation cores from the R to an another type of the monoclinic (MA) phase. Thus, the singular and localized residual strains in the PMN-xPT/STO (001) epitaxial thin films affect the phase stability around the MPB composition and result in the MPB shift phenomena.

Design and analysis of low-loss linear analog phase modulator for deep space spacecraft X-band transponder (DST) application

NASA Technical Reports Server (NTRS)

Mysoor, Narayan R.; Mueller, Robert O.

1991-01-01

This paper summarizes the design concepts, analyses, and the development of an X-band transponder low-loss linear phase modulator for deep space spacecraft applications. A single section breadboard circulator-coupled reflection phase modulator has been analyzed, fabricated, and evaluated. Two- and three-cascaded sections have been modeled and simulations performed to provide an X-band DST phase modulator with +/- 2.5 radians of peak phase deviation to accommodate down-link signal modulation with composite telemetry data and ranging with a deviation linearity tolerance +/- 8 percent and insertion loss of less than 10 +/- 0.5 dB. A two-section phase modulator using constant gamma hyperabrupt varactors and an efficient modulator driver circuit was breadboarded. The measured results satisfy the DST phase modulator requirements, and excellent agreement with the predicted results.

Complex impedance analyses and magnetoelectric effect in ferrite ferroelectric composite ceramics

NASA Astrophysics Data System (ADS)

Patankar, K. K.; Kanade, S. A.; Padalkar, D. S.; Chougule, B. K.

2007-02-01

Magnetoelectric (ME) composites yBa0.8Pb0.2TiO3 (1-y)CuFe2O4 are prepared by ceramic method. The component phases are prepared from two different routes, viz. CuFe2O4 (ferrite phase) is prepared by oxalate precursor route and Ba0.8Pb0.2TiO3 (ferroelectric phase) by solid-state reaction route. No intermediate phases are observed in the composites containing these ferrite and ferroelectric phases. ME conversion factor (measure of ME effect) is found to be enhanced compared to those reported in the composites, in which the component phases were prepared by only one route, i.e. solid-state reaction route. The results on ME conversion are well accounted by measuring the complex impedance and analyzing their Nyquist plots.

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

PubMed Central

Alvarez Feijoo, Miguel Angel

2018-01-01

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (<10 wt %); however, given its mass, the enthalpy detected in the composites was reduced as their loading further increased. The conductive phase combination (PCM + epoxy resin + hardener + thickening agent) presents great potential as a heat-absorbing material at the temperatures employed. PMID:29373538

Novel Formulations of Phase Change Materials-Epoxy Composites for Thermal Energy Storage.

PubMed

Arce, Maria Elena; Alvarez Feijoo, Miguel Angel; Suarez Garcia, Andres; Luhrs, Claudia C

2018-01-26

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (<10 wt %); however, given its mass, the enthalpy detected in the composites was reduced as their loading further increased. The conductive phase combination (PCM + epoxy resin + hardener + thickening agent) presents great potential as a heat-absorbing material at the temperatures employed.

Fully Coupled Micro/Macro Deformation, Damage, and Failure Prediction for SiC/Ti-15-3 Laminates

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M.; Lerch, Brad A.

2001-01-01

The deformation, failure, and low cycle fatigue life of SCS-6/Ti-15-3 composites are predicted using a coupled deformation and damage approach in the context of the analytical generalized method of cells (GMC) micromechanics model. The local effects of inelastic deformation, fiber breakage, fiber-matrix interfacial debonding, and fatigue damage are included as sub-models that operate on the micro scale for the individual composite phases. For the laminate analysis, lamination theory is employed as the global or structural scale model, while GMC is embedded to operate on the meso scale to simulate the behavior of the composite material within each laminate layer. While the analysis approach is quite complex and multifaceted, it is shown, through comparison with experimental data, to be quite accurate and realistic while remaining extremely efficient.

Preparation and characterization of polydimethylsiloxane/poly(vinylalcohol) coated solid phase microextraction fibers using sol-gel technology.

PubMed

Lopes, Alexandre Leite; Augusto, Fabio

2004-11-12

The applicability of a composite composed of polydimethylsiloxane (PDMS) and poly(vinyl alcohol) (PDMS/PVA) as coating sorbent for SPME fibers is demonstrated here. Fused silica (FS) fibers were coated with PDMS/PVA composite through a sol-gel process, using methyltrimethoxysilane as reticulating agent. The chemical and physical properties of the sol-gel PDMS/PVA composite were determined by infrared spectroscopy and thermogravimetric analysis. Electron scanning microscopy of the prepared fibers, showed that the coating obtained was highly microporous, having a thickness of approximately 5 microm. The fibers were tested for the headspace extraction of several organic compounds (o-xylene, naphthalene, ethyl caprate, p-chlorotoluene and PCB) prior to gas chromatographic analysis. The extractive capacity of the PDMS/PVA coating was found to be superior to that of pure conventional PDMS fibers.

Effect of Heat Treatment on Mechanical Properties and Phase Composition of Magnesium-Aluminum Composite Prepared by Explosive Welding

NASA Astrophysics Data System (ADS)

Arisova, V. N.; Trykov, Yu. P.; Slautin, O. V.; Ponomareva, I. A.; Kondakov, A. E.

2015-09-01

Results are given for a study of the effect of heat treatment regimes on the nature of change in micromechanical properties and phase composition of magnesium-aluminum composite material AD1-MA2-1 prepared by explosive welding.

Microscale reconstruction of biogeochemical substrates using multimode X-ray tomography and scanning electron microscopy

NASA Astrophysics Data System (ADS)

Miller, M.; Miller, E.; Liu, J.; Lund, R. M.; McKinley, J. P.

2012-12-01

X-ray computed tomography (CT), scanning electron microscopy (SEM), electron microprobe analysis (EMP), and computational image analysis are mature technologies used in many disciplines. Cross-discipline combination of these imaging and image-analysis technologies is the focus of this research, which uses laboratory and light-source resources in an iterative approach. The objective is to produce images across length scales, taking advantage of instrumentation that is optimized for each scale, and to unify them into a single compositional reconstruction. Initially, CT images will be collected using both x-ray absorption and differential phase contrast modes. The imaged sample will then be physically sectioned and the exposed surfaces imaged and characterized via SEM/EMP. The voxel slice corresponding to the physical sample surface will be isolated computationally, and the volumetric data will be combined with two-dimensional SEM images along CT image planes. This registration step will take advantage of the similarity between the X-ray absorption (CT) and backscattered electron (SEM) coefficients (both proportional to average atomic number in the interrogated volume) as well as the images' mutual information. Elemental and solid-phase distributions on the exposed surfaces, co-registered with SEM images, will be mapped using EMP. The solid-phase distribution will be propagated into three-dimensional space using computational methods relying on the estimation of compositional distributions derived from the CT data. If necessary, solid-phase and pore-space boundaries will be resolved using X-ray differential phase contrast tomography, x-ray fluorescence tomography, and absorption-edge microtomography at a light-source facility. Computational methods will be developed to register and model images collected over varying scales and data types. Image resolution, physically and dynamically, is qualitatively different for the electron microscopy and CT methodologies. Routine CT images are resolved at 10-20 μm, while SEM images are resolved at 10-20 nm; grayscale values vary according to collection time and instrument sensitivity; and compositional sensitivities via EMP vary in interrogation volume and scale. We have so far successfully registered SEM imagery within a multimode tomographic volume and have used standard methods to isolate pore space within the volume. We are developing a three-dimensional solid-phase identification and registration method that is constrained by bulk-sample X-ray diffraction Rietveld refinements. The results of this project will prove useful in fields that require the fine-scale definition of solid-phase distributions and relationships, and could replace more inefficient methods for making these estimations.

Preparation of manganese doped cadmium sulfide nanoparticles in zincblende phase and their magnetic properties.

PubMed

Nakaya, Masafumi; Tanaka, Itaru; Muramatsu, Atsushi

2012-12-01

In this study, the random dope of Mn into CdS nanoparticles in zincblende phase has been carried out under the mild reaction condition. The resulting nanoparticles were characterized by energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV-Vis spectrometer, PL spectrometer, and SQUID. EDX showed that the compositions of Mn doped CdS nanoparticles were readily controlled. TEM showed the particle sizes were not significantly affected by the compositions, retaining to be ca. 3 nm with a narrow size distribution. UV-Vis and PL spectra of the resulting nanoparticles showed the intra-Mn level may be affected by the quantum size effect. SQUID measurement showed that the resulting nanoparticles showed diamagnetism, paramagnetism and superparamagnetism dependent on Mn content.

Improvement of chemical composition, structure and mechanical properties of heat-resistant chromium-nickel alloy

NASA Astrophysics Data System (ADS)

Varlamova, S.; Trushnikova, A.; Rumyantsev, B.; Butrim, V.; Simonov, V.

2018-04-01

A thermodynamic analysis of a multicomponent system of the Cr-Ni alloy (Cr-32Ni-1,5W-0,25V-0,5Ti) with small additions of refractory metals was carried out. The microstructure and phase composition of the base alloy (I) and alloy with additional alloying (II) were studied. The effect of additives on the mechanical properties of the Cr-Ni alloy at 20, 900 and 1080 °C was shown. The microstructure of alloys I and II was studied in the fracture zone of samples after tensile tests at different temperatures. We studied the effect of small additives on the microstructure of alloys and changes in the morphology of the structural components (phases) as a function of temperature and degree of deformation.

The propagation of Lamb waves in multilayered plates: phase-velocity measurement

NASA Astrophysics Data System (ADS)

Grondel, Sébastien; Assaad, Jamal; Delebarre, Christophe; Blanquet, Pierrick; Moulin, Emmanuel

1999-05-01

Owing to the dispersive nature and complexity of the Lamb waves generated in a composite plate, the measurement of the phase velocities by using classical methods is complicated. This paper describes a measurement method based upon the spectrum-analysis technique, which allows one to overcome these problems. The technique consists of using the fast Fourier transform to compute the spatial power-density spectrum. Additionally, weighted functions are used to increase the probability of detecting the various propagation modes. Experimental Lamb-wave dispersion curves of multilayered plates are successfully compared with the analytical ones. This technique is expected to be a useful way to design composite parts integrating ultrasonic transducers in the field of health monitoring. Indeed, Lamb waves and particularly their velocities are very sensitive to defects.

Graphite oxide/β-Ni(OH)2 composites for application in supercapacitors

NASA Astrophysics Data System (ADS)

Singh, Arvinder; Chandra, Amreesh

2013-06-01

Graphite oxide/β-Ni(OH)2 composites have been investigated as electrode material in supercapacitors. Phase formation of electrode material is investigated using diffraction measurements. Particle shape-size studies show deposition of β-Ni(OH)2 nanoparticles on graphite oxide (GO) sheets. Electrochemical performance of GO/β-Ni(OH)2 composite in supercapacitors is discussed based on the analysis of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge studies. Excellent energy density of ˜53 Wh/kg in 1M Na2SO4 aqueous electrolyte is reported at power density of ˜1364W/kg. The significance of results is discussed in the paper.

Study of x CNFO + (1-x) PLZT magnetoelectric composites

NASA Astrophysics Data System (ADS)

Dipti, Singh, Sangeeta; Juneja, J. K.; Pant, R. P.; Raina, K. K.; Prakash, Chandra

2014-04-01

In the present paper, we are reporting the studies on structural, dielectric, ferroelectric and magnetic properties of Lanthanum (La) substituted Lead Zirconate Titanate (PZT) and Cobalt Nickel ferrite (CNFO) composites with compositional formula x(Co0.80Ni0.20Fe2O4)+(1-x)(Pb1.01625La0.0025Zr0.55Ti0.45O3) (x = 0.00,0.10). The materials were synthesized by solid state reaction route. XRD analysis confirms the presence of both ferrite and ferroelectric phases. Dielectric properties were studied as a function of frequency and temperature. Ferroelectric P-E and Magnetic M-H hysteresis loops were measured at room temperature.

Crystal-Chemical Analysis of Soil at Rocknest, Gale Crater

NASA Technical Reports Server (NTRS)

Morrison, S. M.; Downs, R. T.; Blake, D. F.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Yen, A. S.; Chipera, S. J.; Treiman, A. H.; Vaniman, D. T.;

Melioration of Optical and Electrical Performance of Ga-N Codoped ZnO Thin Films

NASA Astrophysics Data System (ADS)

Narayanan, Nripasree; Deepak, N. K.

2018-06-01

Transparent and conducting p-type zinc oxide (ZnO) thin films doped with gallium (Ga) and nitrogen (N) simultaneously were deposited on glass substrates by spray pyrolysis technique. Phase composition analysis by X-ray diffraction confirmed the polycrystallinity of the films with pure ZnO phase. Energy dispersive X-ray analysis showed excellent incorporation of N in the ZnO matrix by means of codoping. The optical transmittance of N monodoped film was poor but got improved with Ga-N codoping and also resulted in the enhancement of optical energy gap. Hole concentration increased with codoping and consequently, lower resistivity and high stability were obtained.

Characterization Data Package for Containerized Sludge Samples Collected from Engineered Container SCS-CON-210

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

Fountain, Matthew S.; Fiskum, Sandra K.; Baldwin, David L.

This data package contains the K Basin sludge characterization results obtained by Pacific Northwest National Laboratory during processing and analysis of four sludge core samples collected from Engineered Container SCS-CON-210 in 2010 as requested by CH2M Hill Plateau Remediation Company. Sample processing requirements, analytes of interest, detection limits, and quality control sample requirements are defined in the KBC-33786, Rev. 2. The core processing scope included reconstitution of a sludge core sample distributed among four to six 4-L polypropylene bottles into a single container. The reconstituted core sample was then mixed and subsampled to support a variety of characterization activities. Additionalmore » core sludge subsamples were combined to prepare a container composite. The container composite was fractionated by wet sieving through a 2,000 micron mesh and a 500-micron mesh sieve. Each sieve fraction was sampled to support a suite of analyses. The core composite analysis scope included density determination, radioisotope analysis, and metals analysis, including the Waste Isolation Pilot Plant Hazardous Waste Facility Permit metals (with the exception of mercury). The container composite analysis included most of the core composite analysis scope plus particle size distribution, particle density, rheology, and crystalline phase identification. A summary of the received samples, core sample reconstitution and subsampling activities, container composite preparation and subsampling activities, physical properties, and analytical results are presented. Supporting data and documentation are provided in the appendices. There were no cases of sample or data loss and all of the available samples and data are reported as required by the Quality Assurance Project Plan/Sampling and Analysis Plan.« less

A two-phase restricted equilibrium model for combustion of metalized solid propellants

NASA Technical Reports Server (NTRS)

Sabnis, J. S.; Dejong, F. J.; Gibeling, H. J.

1992-01-01

An Eulerian-Lagrangian two-phase approach was adopted to model the multi-phase reacting internal flow in a solid rocket with a metalized propellant. An Eulerian description was used to analyze the motion of the continuous phase which includes the gas as well as the small (micron-sized) particulates, while a Lagrangian description is used for the analysis of the discrete phase which consists of the larger particulates in the motor chamber. The particulates consist of Al and Al2O3 such that the particulate composition is 100 percent Al at injection from the propellant surface with Al2O3 fraction increasing due to combustion along the particle trajectory. An empirical model is used to compute the combustion rate for agglomerates while the continuous phase chemistry is treated using chemical equilibrium. The computer code was used to simulate the reacting flow in a solid rocket motor with an AP/HTPB/Al propellant. The computed results show the existence of an extended combustion zone in the chamber rather than a thin reaction region. The presence of the extended combustion zone results in the chamber flow field and chemical being far from isothermal (as would be predicted by a surface combustion assumption). The temperature in the chamber increases from about 2600 K at the propellant surface to about 3350 K in the core. Similarly the chemical composition and the density of the propellant gas also show spatially non-uniform distribution in the chamber. The analysis developed under the present effort provides a more sophisticated tool for solid rocket internal flow predictions than is presently available, and can be useful in studying apparent anomalies and improving the simple correlations currently in use. The code can be used in the analysis of combustion efficiency, thermal load in the internal insulation, plume radiation, etc.

Multilayer Electroactive Polymer Composite Material

NASA Technical Reports Server (NTRS)

Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

2011-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

2009-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Thermoset molecular composites

DOEpatents

Benicewicz, Brian C.; Douglas, Elliot P.; Hjelm, Jr., Rex P.

1996-01-01

A polymeric composition including a liquid crystalline polymer and a thermosettable liquid crystalline monomer matrix, said polymeric composition characterized by a phase separation on the scale of less than about 500 Angstroms and a polymeric composition including a liquid crystalline polymer and a liquid crystalline thermoset matrix, said polymeric composition characterized by a phase separation on the scale of less than about 500 Angstroms are disclosed.

Ratioed scatter diagrams - An erotetic method for phase identification on complex surfaces using scanning Auger microscopy

NASA Technical Reports Server (NTRS)

Browning, R.

1984-01-01

By ratioing multiple Auger intensities and plotting a two-dimensional occupational scatter diagram while digitally scanning across an area, the number and elemental association of surface phases can be determined. This can prove a useful tool in scanning Auger microscopic analysis of complex materials. The technique is illustrated by results from an anomalous region on the reaction zone of a SiC/Ti-6Al-4V metal matrix composite material. The anomalous region is shown to be a single phase associated with sulphur and phosphorus impurities. Imaging of a selected phase from the ratioed scatter diagram is possible and may be a useful technique for presenting multiple scanning Auger images.

Design and fabrication of advanced materials from Illinois coal wastes. Quarterly report, 1 March 1995--31 May 1995

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

Malhotra, V.M.; Wright, M.A.

1995-12-31

The main goal of this project is to develop a bench-scale procedure to design and fabricate advanced brake and structural composite materials from Illinois coal combustion residues. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), differential thermal analysis (DTA), and transmission-Fourier transform infrared (FTIR) were conducted on PCC fly ash (Baldwin), FBC fly ash (ADM unit1-6), FBC fly ash (S.I. coal), FBC spent bed ash (ADM unit1-6), bottom ash, and scrubber sludge (CWLP) residues to characterize their geometrical shapes, mineral phases, and thermal stability. Our spectroscopic results indicate that the scrubber sludge is mainly composed of a gypsum-like phase whosemore » lattice structure is different from the lattice structure of conventional gypsum, and sludge does not contain hannebachite (CaSO{sub 3}0.5H{sub 2}O) phase. In the second and third quarters the focus of research has been on developing protocols for the formation of advanced brake composites and structural composites. Our attempts to fabricate brake frictional shoes, in the form of 1.25 inch disks, from PCC fly ash, FBC spent bed ash, scrubber sludge, coal char, iron particles, and coal tar were successful. Based on the experience gained and microscopic analyses, we have now upscaled our procedures to fabricate 2.5 inch diameter disks from coal combustion residues. The SEM and Young`s modulus analyses of brake composites fabricated at 400 psi < Pressure < 2200 psi suggest pressure has a strong influence on the particle packing and the filling of interstices in our composites.« less

Chemical and isotopic composition of secondary organic aerosol generated by α-pinene ozonolysis

NASA Astrophysics Data System (ADS)

Meusinger, Carl; Dusek, Ulrike; King, Stephanie M.; Holzinger, Rupert; Rosenørn, Thomas; Sperlich, Peter; Julien, Maxime; Remaud, Gerald S.; Bilde, Merete; Röckmann, Thomas; Johnson, Matthew S.

2017-05-01

Secondary organic aerosol (SOA) plays a central role in air pollution and climate. However, the description of the sources and mechanisms leading to SOA is elusive despite decades of research. While stable isotope analysis is increasingly used to constrain sources of ambient aerosol, in many cases it is difficult to apply because neither the isotopic composition of aerosol precursors nor the fractionation of aerosol forming processes is well characterised. In this paper, SOA formation from ozonolysis of α-pinene - an important precursor and perhaps the best-known model system used in laboratory studies - was investigated using position-dependent and average determinations of 13C in α-pinene and advanced analysis of reaction products using thermal-desorption proton-transfer-reaction mass spectrometry (PTR-MS). The total carbon (TC) isotopic composition δ13C of the initial α-pinene was measured, and the δ13C of the specific carbon atom sites was determined using position-specific isotope analysis (PSIA). The PSIA analysis showed variations at individual positions from -6.9 to +10. 5 ‰ relative to the bulk composition. SOA was formed from α-pinene and ozone in a constant-flow chamber under dark, dry, and low-NOx conditions, with OH scavengers and in the absence of seed particles. The excess of ozone and long residence time in the flow chamber ensured that virtually all α-pinene had reacted. Product SOA was collected on two sequential quartz filters. The filters were analysed offline by heating them stepwise from 100 to 400 °C to desorb organic compounds that were (i) detected using PTR-MS for chemical analysis and to determine the O : C ratio, and (ii) converted to CO2 for 13C analysis. More than 400 ions in the mass range 39-800 Da were detected from the desorbed material and quantified using a PTR-MS. The largest amount desorbed at 150 °C. The O : C ratio of material from the front filter increased from 0.18 to 0.25 as the desorption temperature was raised from 100 to 250 °C. At temperatures above 250 °C, the O : C ratio of thermally desorbed material, presumably from oligomeric precursors, was constant. The observation of a number of components that occurred across the full range of desorption temperatures suggests that they are generated by thermal decomposition of oligomers. The isotopic composition of SOA was more or less independent of desorption temperature above 100 °C. TC analysis showed that SOA was enriched in 13C by 0.6-1.2 ‰ relative to the initial α-pinene. According to mass balance, gas-phase products will be depleted relative to the initial α-pinene. Accordingly, organic material on the back filters, which contain adsorbed gas-phase compounds, is depleted in 13C in TC by 0.7 ‰ relative to the initial α-pinene, and by 1.3 ‰ compared to SOA collected on the front filter. The observed difference in 13C between the gas and particle phases may arise from isotope-dependent changes in the branching ratios in the α-pinene + O3 reaction. Alternatively, some gas-phase products involve carbon atoms from highly enriched and depleted sites, as shown in the PSIA analysis, giving a non-kinetic origin to the observed fractionations. In either case, the present study suggests that the site-specific distribution of 13C in the source material itself governs the abundance of 13C in SOA.

Synthesis and Screening of Phase Change Chalcogenide Thin Film Materials for Data Storage.

PubMed

Guerin, Samuel; Hayden, Brian; Hewak, Daniel W; Vian, Chris

2017-07-10

A combinatorial synthetic methodology based on evaporation sources under an ultrahigh vacuum has been used to directly synthesize compositional gradient thin film libraries of the amorphous phases of GeSbTe alloys at room temperature over a wide compositional range. An optical screen is described that allows rapid parallel mapping of the amorphous-to-crystalline phase transition temperature and optical contrast associated with the phase change on such libraries. The results are shown to be consistent with the literature for compositions where published data are available along the Sb 2 Te 3 -GeTe tie line. The results reveal a minimum in the crystallization temperature along the Sb 2 Te 3 -Ge 2 Te 3 tie line, and the method is able to resolve subsequent cubic-to-hexagonal phase transitions in the GST crystalline phase. HT-XRD has been used to map the phases at sequentially higher temperatures, and the results are reconciled with the literature and trends in crystallization temperatures. The results clearly delineate compositions that crystallize to pure GST phases and those that cocrystallize Te. High-throughput measurement of the resistivity of the amorphous and crystalline phases has allowed the compositional and structural correlation of the resistivity contrast associated with the amorphous-to-crystalline transition, which range from 5-to-8 orders of magnitude for the compositions investigated. The results are discussed in terms of the compromises in the selection of these materials for phase change memory applications and the potential for further exploration through more detailed secondary screening of doped GST or similar classes of phase change materials designed for the demands of future memory devices.

Topologically Close-packed Phase Formation in High Entropy Alloys: A Review of Calphad and Experimental Results

NASA Astrophysics Data System (ADS)

Guruvidyathri, K.; Hari Kumar, K. C.; Yeh, J. W.; Murty, B. S.

2017-11-01

One of the major challenges in high entropy alloy (HEA) research is to obtain single-phase solid solutions by proper selection of components and processing techniques. Often one encounters situations where topologically close-packed (TCP) phases are present in the HEA microstructures. TCP phases are a class of intermetallic phases that are in general considered undesirable. The ability to predict these phases in HEAs using the Calphad (CALculation of PHAse Diagrams) method has been shown to accelerate the identification of promising compositions. In this review, an analysis of the reported Calphad studies and corresponding microstructural information on HEAs is done to evaluate the success of the Calphad method for TCP phases. A total of 52 alloys with 123 post-heat treatment microstructures reported so far have been compared. Challenges and issues in experiments and calculations are brought out with a possible way forward.

Effect of heat treatment on phase composition and crystal structure of thin WSi2 films on silicon substrates

NASA Astrophysics Data System (ADS)

Biryukov, Y. P.; Dostanko, A. P.; Maltsev, A. A.; Shakhlevich, G. M.

1984-10-01

An experimental study of WSi2 films on silicon substrates with either 111 or 100 orientation was made, for the purpose of determining the effect of annealing by heat treatment on their phase composition and crystal structure. Films of 0.2 micron thickness were deposited at a rate of 0.5 nm/s on a silicon surface which was predecontaminated of SiO2 layers and adsorbate atoms by ion sputtering in one vacuum cycle. Deposition was by condensation, with the substrate held at various temperatures from 390 to 500 C, and then annealed in an argon atmosphere at various temperatures from 700 to 1000 C for 30 min. Subsequent phase analysis at room temperature was performed with a DRON-2 X-ray diffractometer, using a CuK (sub alpha)-radiation source and covering the 20 = 10 to 130 deg range of angles by the Debye-Sherer method, while the surface morphology was examined under an electron microscope.

Sol-gel synthesis and adsorption properties of mesoporous manganese oxide

NASA Astrophysics Data System (ADS)

Ivanets, A. I.; Kuznetsova, T. F.; Prozorovich, V. G.

2015-03-01

Sol-gel synthesis of mesoporous xerogels of manganese oxide with different phase compositions has been performed. The manganese oxide sols were obtained by redox reactions of potassium permanganate with hydrogen peroxide or manganese(II) chloride in aqueous solutions. The isotherms of the low-temperature adsorption-desorption of nitrogen with manganese oxide xerogels treated at 80, 200, 400, and 600°C were measured. The samples were studied by electron microscopy and thermal and XRD analysis. The phase transformation and the changes in the adsorption and capillary-condensation properties of manganese oxide were shown to depend on the sol synthesis conditions and the temperature of the thermal treatment of the gel. The X-ray amorphous samples heated at 80°C were shown to have low values of the specific surface; at higher temperatures, the xerogel crystallized into mixed phases with various compositions and its surface area increased at 200-400°C and decreased at 600°C.

Study on crystallization kinetics and phase evolution in Li2O-Al2O3-GeO2-P2O5 glass-ceramics system

NASA Astrophysics Data System (ADS)

Das, Anurup; Dixit, Anupam; Goswami, Madhumita; Mythili, R.; Hajra, R. N.

2018-04-01

To address the safety issues related to liquid electrolyte and improve the battery performance, Solid State Electrolytes (SSEs) are now in frontier area of research interest. We report here synthesis of Li-SSE based on Li2O-Al2O3-GeO2-P2O5 (LAGP) system with NASICON structure. Glass sample with nominal composition Li1.5Al0.5Ge1.5P2.5Si0.5O12 was prepared by melt-quenching technique. Non-isothermal crystallization kinetics was studied using DSC and activation energy of crystallisation was calculated to be ˜ 246 kJ/mol using Kissinger's equation. XRD of heat treated samples show the formation of required LiGe2(PO4)3 phase along with other minor phases. Compositional analysis using SEM-EDX confirms enrichment of Ge and Si along the grain boundaries.

Nonstoichiometric fluorides—Solid electrolytes for electrochemical devices: A review

NASA Astrophysics Data System (ADS)

Sorokin, N. I.; Sobolev, B. P.

2007-09-01

The solid electrolytes with fluorine-ion conductivity that were revealed during the analysis of the phase diagrams of the MF m - RF n systems within the program of search for new multicomponent fluoride crystalline materials carried out at the Shubnikov Institute of Crystallography, Russian Academy of Sciences, are described. The most widespread and promising materials are the nonstoichiometric phases with fluorite (CaF2) and tysonite (LaF3) structures, which are formed in the MF2- RF3 systems ( M = Ca, Sr, Ba, Cd, or Pb; R = Sc, Y, or La-Lu). These phases have superionic fluorine conductivity due to the anion sublattice disorder. The ionic conductivity of crystals of both structure types has been studied and the limits of its change with composition and temperature are determined. Nonstoichiometric fluorides are used as solid electrolytes in chemical sensors, fluorine sources, and batteries. The prospects of the use of fluorine-ion conductors in solid-state electrochemical devices, principles of their operation, and the problems of optimization of their composition are discussed.

Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

PubMed

Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

2014-03-01

During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The Amorphous Composition of Three Mudstone Samples from Gale Crater: Implications for Weathering and Diagenetic Processes on Mars

NASA Technical Reports Server (NTRS)

Achilles, C. N.; Downs, R. T.; Rampe, E. B.; Morris, R. V.; Bristow, T. F.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.; Morrison, S. M.; Sutter, B.;

Nanostructured LiMPO4 (M = Fe, Mn, Co, Ni) - carbon composites as cathode materials for Li-ion battery

NASA Astrophysics Data System (ADS)

Dimesso, L.; Spanheimer, C.; Nguyen, T. T. D.; Hausbrand, R.; Jaegermann, W.

2012-10-01

Nanostructured materials are considered to be strong candidates for fundamental advances in efficient storage and/or conversion. In nanostructured materials transport kinetics and surface processes play determining roles. This work describes recent developments in the synthesis and characterization of composites which consist of lithium metal phosphates (LiMPO4, M = Fe, Mn, Co, Ni) coated on nanostructured carbon supports (unordered nanofibers, foams). The composites have been prepared by coating the carbon structures in aqueous (or polyols) solutions containing lithium, metal ions and phosphates. After drying out, the composites have been thermally treated at different temperatures (between 600-780°C) for 5-12 hours under nitrogen. The formation of the olivine structured phase was confirmed by the X-ray diffraction analysis on powders prepared under very similar conditions. The surface investigation revealed the formation of an homogeneous coating of the olivine phase on the carbon structures. The electrochemical performance on the composites showed a dramatic improvement of the discharge specific capacity (measured at a discharge rate of C/25 and room temperature) compared to the prepared powders. The delivered values were 105 mAhg-1 for M = Fe, 100 mAhg-1 for M = Co, 70 mAhg-1 for M = Mn and 30 mAhg-1 for M = Ni respectively.

X-ray diffraction analysis of Nb-3Ge and NbGe alloys

NASA Technical Reports Server (NTRS)

Davis, J. H.; House, K. W.

1983-01-01

Of all the A-15 samples of NbGe alloy examined, DT 094 is unique in that it was at least 99% pure A-15 phase. Also its diffraction peaks were noisy as if there were about a one percent compositional variation on this phase. DT 094, however, was only a large fragment of the drop tube drop, and thus its small sample size may have reduced the intensity, thus enhancing fluctuations enough to explain some of the loss of peak resolution.

Phase equilibria of H2SO4, HNO3, and HCl hydrates and the composition of polar stratospheric clouds

NASA Technical Reports Server (NTRS)

Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

1995-01-01

Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

Phase Equilibria of H2SO4, HNO3, and HCl Hydrates and the Composition of Polar Stratospheric Clouds

NASA Technical Reports Server (NTRS)

Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

1995-01-01

Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

Applications of High Throughput (Combinatorial) Methodologies to Electronic, Magnetic, Optical, and Energy-Related Materials

DTIC Science & Technology

2013-06-17

of the films without having to fabricate capacitors. In addition, the use of X - ray diffraction (XRD) analysis enabled Chikyow et al.40 to identify an...effects of Al doping and annealing on the thermal stabil- ity of the Y2O3/Si gate stack were studied by X - ray photoemission spectroscopy (XPS) and X - ray ...the major diffraction features in the phase distribution. For a given structural phase, the X - ray peak intensity allows one to track the compositional

Solid-phase microextraction fiber development for sampling and analysis of volatile organohalogen compounds in air.

PubMed

Attari, Seyed Ghavameddin; Bahrami, Abdolrahman; Shahna, Farshid Ghorbani; Heidari, Mahmoud

2014-01-01

A green, environmental friendly and sensitive method for determination of volatile organohalogen compounds was described in this paper. The method is based on a homemade sol-gel single-walled carbon nanotube/silica composite coated solid-phase microextraction to develop for sampling and analysis of Carbon tetrachloride, Benzotrichloride, Chloromethyl methyl ether and Trichloroethylene in air. Application of this method was investigated under different laboratory conditions. Predetermined concentrations of each analytes were prepared in a home-made standard chamber and the influences of experimental parameters such as temperature, humidity, extraction time, storage time, desorption temperature, desorption time and the sorbent performance were investigated. Under optimal conditions, the use of single-walled carbon nanotube/silica composite fiber showed good performance, high sensitive and fast sampling of volatile organohalogen compounds from air. For linearity test the regression correlation coefficient was more than 98% for analyte of interest and linear dynamic range for the proposed fiber and the applied Gas Chromatography-Flame Ionization Detector technique was from 1 to 100 ngmL(-1). Method detection limits ranged between 0.09 to 0.2 ngmL(-1) and method quantification limits were between 0.25 and 0.7 ngmL(-1). Single-walled carbon nanotube/silica composite fiber was highly reproducible, relative standard deviations were between 4.3 to 11.7 percent.

Multivariate areal analysis of the impact and efficiency of the family planning programme in peninsular Malaysia.

PubMed

Tan Boon Ann

1987-06-01

The findings of the final phase of a 3-phase multivariate areal analysis study undertaken by the Economic and Social Commission for Asia and the Pacific (ESCAP) in 5 countries of the Asian and Pacific Region, including Malaysia, to examine the impact of family planning programs on fertility and reproduction are reported. The study used Malaysia's administrative district as the unit of analysis because the administration and implementation of socioeconomic development activities, as well as the family planning program, depend to a large extent on the decisions of local organizations at the district or state level. In phase 1, existing program and nonprogram data were analyzed using the multivariate technique to separate the impact of the family planning program net of other developmental efforts. The methodology in the 2nd phase consisted of in-depth investigation of selected areas in order to discern the dynamics and determinants of efficiency. The insights gained in phase 2 regarding dynamics of performance were used in phase 3 to refine the input variables of the phase 1 model. Thereafter, the phase 1 analysis was repeated. Insignificant variables and factors were trimmed in order to present a simplified model for studying the impact of environmental, socioeconomic development, family planning programs, and related factors on fertility. The inclusion of a set of family planning program and development variables in phase 3 increased the predictive power of the impact model. THe explained variance for total fertility rate (TFR) of women under 30 years increased from 71% in phase 1 to 79%. It also raised the explained variance of the efficiency model from 34% to 70%. For women age 30 years and older, their TFR was affected directly by the ethnic composition variable (.76), secondary educational status (-.45), and modern nonagricultural occupation (.42), among others. When controlled for other socioeconomic development and environmental indicators, the nonagricultural activities had a positive direct effect on TFR. No direct effects were found to come from other socioeconomic development indicators, once these factors were controlled. The 3 factors that had direct effects on the fertility of women below age 30 were ethnic composition (.33), contraceptive pevalence (-.32), and secondary educational status (-.25). Other family planning program variables (contraceptive knowledge) and socioeconomic development indicators (exposure to modernization as measured by television ownership and health/living conditions as measured by infant mortality rate) affected fertility significantly but indirectly.

Determination of the succinonitrile-benzene and succinonitrile-cyclohexanol phase diagrams by thermal and UV spectroscopic analysis

NASA Technical Reports Server (NTRS)

Kaukler, W. F.; Frazier, D. O.; Facemire, B.

1984-01-01

Equilibrium temperature-composition diagrams were determined for the two organic systems, succinonitrile-benzene and succinonitrile-cyclohexanol. Measurements were made using the common thermal analysis methods and UV spectrophotometry. Succinonitrile-benzene monotectic was chosen for its low affinity for water and because UV analysis would be simplified. Succinonitrile-cyclohexanol was chosen because both components are transparent models for metallic solidification, as opposed to the other known succinonitrile-based monotectics.

Glass/polymer composites and methods of making

DOEpatents

Samuels, W. D.; Exarhos, Gregory J.

1995-01-01

The present invention relates to new glass/polymer composites and methods for making them. More specifically, the invention is glass/polymer composites having phases that are at the molecular level and thereby practicably indistinguishable. The invention further discloses making molecular phase glass/polymer composites by mixing a glass and a polymer in a compatible solvent.

Glass/polymer composites and methods of making

DOEpatents

Samuels, W.D.; Exarhos, G.J.

1995-06-06

The present invention relates to new glass/polymer composites and methods for making them. More specifically, the invention is glass/polymer composites having phases that are at the molecular level and thereby practicably indistinguishable. The invention further discloses making molecular phase glass/polymer composites by mixing a glass and a polymer in a compatible solvent.

High Curie temperature and enhanced magnetoelectric properties of the laminated Li0.058(Na0.535K0.48)0.942NbO3/Co0.6 Zn0.4Fe1.7Mn0.3O4 composites

PubMed Central

Yang, Haibo; Zhang, Jintao; Lin, Ying; Wang, Tong

2017-01-01

Laminated magnetoelectric composites of Li0.058(Na0.535K0.48)0.942NbO3 (LKNN)/Co0.6Zn0.4Fe1.7Mn0.3O4 (CZFM) prepared by the conventional solid-state sintering method were investigated for their dielectric, magnetic, and magnetoelectric properties. The microstructure of the laminated composites indicates that the LKNN phase and CZFM phase can coexist in the composites. Compared with the particulate magnetoelectric composites, the laminated composites have better piezoelectric and magnetoelectric properties due to their higher resistances and lower leakage currents. The magnetoelectric behaviors lie on the relative mass ratio of LKNN phase and CZFM phase. The laminated composites possess a high Curie temperature (TC) of 463 °C, and the largest ME coefficient of 285 mV/cm Oe, which is the highest value for the lead-free bulk ceramic magnetoelectric composites so far. PMID:28338006

Zirconia toughened mica glass ceramics for dental restorations.

PubMed

Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

2018-03-01

The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Natural Silica Sand/Alumina Ceramic Composites: Promising Candidates for Fuel-Cell Sealants

NASA Astrophysics Data System (ADS)

Hidayat, N.; Istiqomah; Widianto, M. Y. H.; Taufiq, A.; Sunaryono; Triwikantoro; Zainuri, M.; Baqiya, M. A.; Aristia, G.; Pratapa, S.

2017-05-01

An attempt has been developed to establish the prospect of the useful application of Indonesian natural silica sand, instead of commercially expensive materials, as a future fuel-cell sealant. The sand was initially washed and ball-milled at 150 rpm for 60 minutes and then heated at 1000 °C for the same duration. The resulting powder was then mixed with alumina powder at various amounts and shaped into discs before sintering at 1150 °C and 1250 °C to produce compact ceramics. The diameter shrinkage, porosity, and density of the ceramics were evaluated by Archimedes method. Their crystalline phase composition was quantified by Rietveld refinement analysis on the X-ray diffraction (XRD) data and the phase weight fraction was then used for coefficient of thermal expansion (CTE) evaluation. It was observed that the bulk density increased while the porosity decreased with alumina addition. The XRD data analysis revealed that the prepared silica sand contains a very high purity of quartz-SiO2, i.e. 97.8(18)%. The sintering temperatures of 1150 °C and 1250 °C transformed some quartz-SiO2 to crystobalite-SiO2. All the calcite-CaCO3 exhibited reaction sintering with SiO2 forming wollastonite-CaSiO3. Therefore, the ceramic composites contained SiO2/Al2O3/CaSiO3. Regarding CTE, all of the composites meet the criteria for fuel-cell sealants, in the range of 9-12 ppm/°C.

Piezoelectric and pyroelectric properties of PZT/P(VDF-TrFE) composites with constituent phases poled in parallel or antiparallel directions.

PubMed

Ng, K L; Chan, H L; Choy, C L

2000-01-01

Composites of lead zirconate titanate (PZT) powder dispersed in a vinylidene fluoride-trifluoroethylene copolymer [P(VDF-TrFE)] matrix have been prepared by compression molding. Three groups of polarized samples have been prepared by poling: only the ceramic phase, the ceramic and polymer phases in parallel directions, and the two phases in antiparallel directions. The measured permittivities of the unpoled composites are consistent with the predictions of the Bruggeman model. The changes in the pyroelectric and piezoelectric coefficients of the poled composites with increasing ceramic volume fraction can be described by modified linear mixture rules. When the ceramic and copolymer phases are poled in the same direction, their pyroelectric activities reinforce while their piezoelectric activities partially cancel. However, when the ceramic and copolymer phases are poled in opposite directions, their piezoelectric activities reinforce while their pyroelectric activities partially cancel.

Delamination Detection Using Guided Wave Phased Arrays

NASA Technical Reports Server (NTRS)

Tian, Zhenhua; Yu, Lingyu; Leckey, Cara

2016-01-01

This paper presents a method for detecting multiple delaminations in composite laminates using non-contact phased arrays. The phased arrays are implemented with a non-contact scanning laser Doppler vibrometer (SLDV). The array imaging algorithm is performed in the frequency domain where both the guided wave dispersion effect and direction dependent wave properties are considered. By using the non-contact SLDV array with a frequency domain imaging algorithm, an intensity image of the composite plate can be generated for delamination detection. For the proof of concept, a laboratory test is performed using a non-contact phased array to detect two delaminations (created through quasi-static impact test) at different locations in a composite plate. Using the non-contact phased array and frequency domain imaging, the two impact-induced delaminations are successfully detected. This study shows that the non-contact phased array method is a potentially effective method for rapid delamination inspection in large composite structures.

Holonomy of a principal composite bundle connection, non-Abelian geometric phases, and gauge theory of gravity

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

Viennot, David

We show that the holonomy of a connection defined on a principal composite bundle is related by a non-Abelian Stokes theorem to the composition of the holonomies associated with the connections of the component bundles of the composite. We apply this formalism to describe the non-Abelian geometric phase (when the geometric phase generator does not commute with the dynamical phase generator). We find then an assumption to obtain a new kind of separation between the dynamical and the geometric phases. We also apply this formalism to the gauge theory of gravity in the presence of a Dirac spinor field inmore » order to decompose the holonomy of the Lorentz connection into holonomies of the linear connection and of the Cartan connection.« less

Diffraction, microstructure and thermal stability analysis in a double phase nanocrystalline Al20Mg20Ni20Cr20Ti20 high entropy alloy

NASA Astrophysics Data System (ADS)

Rameshbabu, A. M.; Parameswaran, P.; Vijayan, V.; Panneer, R.

2017-12-01

An effort has been made to develop a new composition of AlMgNiCrTi high entropy alloy (HEA) with a distinct properties includes squat density, intense strength and hardness, superior corrosion resistance, better oxidation resistance, high temperature resistance, fatigue load and crack resistance to congregate the necessity of aircraft applications. The equivalent atomic percentage for the above defined composition is established using analytical correlation for molar and atom renovation by trial and error method. The alloy is synthesized by powder metallurgy technique through mechanical alloying. Succeeding to mechanical alloying it is elucidated that the metal powder is primarily composed of single BCC solid solution with crystallite magnitude <10 nm. It is also observed that the alloy is thermally stable at prominent temperature about 800°C as it is retained its nanostructure which was revealed using differential scanning caloriemetry (DSC). This alloy powder was consolidated and sintered using spark plasma sintering at 800°C with 50 Mpa pressure to a density of 98.83%. Subsequent to sintering, Titanium carbide FCC phase evolved along with the BCC phase. The alloying behavior and phase transformation were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM). The homogeneity of the composition is confirmed by energy dispersive spectroscopy (EDS). The hardness of the alloy is found to be 710±20 HV. The evolutions of the phases and hardness imply that this alloy is apposite for both high strength and high temperature applications.

Aeroelastic response and blade loads of a composite rotor in forward flight

NASA Technical Reports Server (NTRS)

Smith, Edward C.; Chopra, Inderjit

1992-01-01

The aeroelastic response, blade and hub loads, and shaft-fixed aeroelastic stability is investigated for a helicopter with elastically tailored composite rotor blades. A new finite element based structural analysis including nonclassical effects such as transverse shear, torsion related warping and inplane elasticity is integrated with the University of Maryland Advanced Rotorcraft Code. The structural dynamics analysis is correlated against both experimental data and detailed finite element results. Correlation of rotating natural frequencies of coupled composite box-beams is generally within 5-10 percent. The analysis is applied to a soft-inplane hingeless rotor helicopter in free flight propulsive trim. For example, lag mode damping can be increased 300 percent over a range of thrust conditions and forward speeds. The influence of unsteady aerodynamics on the blade response and vibratory hub loads is also investigated. The magnitude and phase of the flap response is substantially altered by the unsteady aerodynamic effects. Vibratory hub loads increase up to 30 percent due to unsteady aerodynamic effects.

Modelling Equilibrium and Fractional Crystallization in the System MgO-FeO-CaO-Al2O3-SiO2

NASA Technical Reports Server (NTRS)

Herbert, F.

1985-01-01

A mathematical modelling technique for use in petrogenesis calculations in the system MgO-FeO-CaO-Al2O3-SiO2 is reported. Semiempirical phase boundary and elemental distribution information was combined with mass balance to compute approximate equilibrium crystallization paths for arbitrary system compositions. The calculation is applicable to a range of system compositions and fractionation calculations are possible. The goal of the calculation is the computation of the composition and quantity of each phase present as a function of the degree of solidification. The degree of solidification is parameterized by the heat released by the solidifying phases. The mathematical requirement for the solution of this problem is: (1) An equation constraining the composition of the magma for each solid phase in equilibrium with the liquidus phase, and (2) an equation for each solid phase and each component giving the distribution of that element between that phase and the magma.

Tool for Generation of MAC/GMC Representative Unit Cell for CMC/PMC Analysis

NASA Technical Reports Server (NTRS)

Murthy, Pappu L. N.; Pineda, Evan J.

2016-01-01

This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) 4.0. This tool is especially useful in analyzing ceramic matrix composites (CMCs), where higher fidelity with improved accuracy of local response is needed. The tool, however, can be used for analyzing polymer matrix composites (PMCs) as well. MAC/GMC 4.0 is a composite material and laminate analysis software developed at NASA Glenn Research Center. The software package has been built around the concept of the generalized method of cells (GMC). The computer code is developed with a user friendly framework, along with a library of local inelastic, damage, and failure models. Further, application of simulated thermomechanical loading, generation of output results, and selection of architectures to represent the composite material have been automated to increase the user friendliness, as well as to make it more robust in terms of input preparation and code execution. Finally, classical lamination theory has been implemented within the software, wherein GMC is used to model the composite material response of each ply. Thus, the full range of GMC composite material capabilities is available for analysis of arbitrary laminate configurations as well. The primary focus of the current effort is to provide a graphical user interface (GUI) capability that generates a number of different user-defined repeating unit cells (RUCs). In addition, the code has provisions for generation of a MAC/GMC-compatible input text file that can be merged with any MAC/GMC input file tailored to analyze composite materials. Although the primary intention was to address the three different constituents and phases that are usually present in CMCs-namely, fibers, matrix, and interphase-it can be easily modified to address two-phase polymer matrix composite (PMC) materials where an interphase is absent. Currently, the tool capability includes generation of RUCs for square packing, hexagonal packing, and random fiber packing as well as RUCs based on actual composite micrographs. All these options have the fibers modeled as having a circular cross-sectional area. In addition, a simplified version of RUC is provided where the fibers are treated as having a square cross section and are distributed randomly. This RUC facilitates a speedy analysis using the higher fidelity version of GMC known as HFGMC. The first four mentioned options above support uniform subcell discretization. The last one has variable subcell sizes due to the primary intention of keeping the RUC size to a minimum to gain the speed ups using the higher fidelity version of MAC. The code is implemented within the MATLAB (The Mathworks, Inc., Natick, MA) developmental framework; however, a standalone application that does not need a priori MATLAB installation is also created with the aid of the MATLAB compiler.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Scale-dependent effects on wave propagation in magnetically affected single/double-layered compositionally graded nanosize beams

NASA Astrophysics Data System (ADS)

Ebrahimi, Farzad; Barati, Mohammad Reza

2018-04-01

This article deals with the wave propagation analysis of single/double layered functionally graded (FG) size-dependent nanobeams in elastic medium and subjected to a longitudinal magnetic field employing nonlocal elasticity theory. Material properties of nanobeam change gradually according to the sigmoid function. Applying an analytical solution, the acoustical and optical dispersion relations are explored for various wave number, nonlocality parameter, material composition, elastic foundation constants, and magnetic field intensity. It is found that frequency and phase velocity of waves propagating in S-FGM nanobeam are significantly affected by these parameters. Also, presence of cut-off and escape frequencies in wave propagation analysis of embedded S-FGM nanobeams is investigated.

Colossal Tooling Design: 3D Simulation for Ergonomic Analysis

NASA Technical Reports Server (NTRS)

Hunter, Steve L.; Dischinger, Charles; Thomas, Robert E.; Babai, Majid

2003-01-01

The application of high-level 3D simulation software to the design phase of colossal mandrel tooling for composite aerospace fuel tanks was accomplished to discover and resolve safety and human engineering problems. The analyses were conducted to determine safety, ergonomic and human engineering aspects of the disassembly process of the fuel tank composite shell mandrel. Three-dimensional graphics high-level software, incorporating various ergonomic analysis algorithms, was utilized to determine if the process was within safety and health boundaries for the workers carrying out these tasks. In addition, the graphical software was extremely helpful in the identification of material handling equipment and devices for the mandrel tooling assembly/disassembly process.

Highly sensitive analysis of polycyclic aromatic hydrocarbons in environmental water with porous cellulose/zeolitic imidazolate framework-8 composite microspheres as a novel adsorbent coupled with high-performance liquid chromatography.

PubMed

Liang, Xiaotong; Liu, Shengquan; Zhu, Rong; Xiao, Lixia; Yao, Shouzhuo

2016-07-01

In this work, novel cellulose/zeolitic imidazolate frameworks-8 composite microspheres have been successfully fabricated and utilized as sorbent for environmental polycyclic aromatic hydrocarbons efficient extraction and sensitive analysis. The composite microspheres were synthesized through the in situ hydrothermal growth of zeolitic imidazolate frameworks-8 on cellulose matrix, and exhibited favorable hierarchical structure with chemical composition as assumed through scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, and Brunauer-Emmett-Teller surface areas characterization. A robust and highly efficient method was then successfully developed with as-prepared composite microspheres as novel solid-phase extraction sorbent with optimum extraction conditions, such as sorbent amount, sample volume, extraction time, desorption conditions, volume of organic modifier, and ionic strength. The method exhibited high sensitivity with low limit of detection down to 0.1-1.0 ng/L and satisfactory linearity with correlation coefficients ranging from 0.9988 to 0.9999, as well as good recoveries of 66.7-121.2% with relative standard deviations less than 10% for environmental polycyclic aromatic hydrocarbons analysis. Thus, our method was convenient and efficient for polycyclic aromatic hydrocarbons extraction and detection, potential for future environmental water samples analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Haplotype Phasing and Inheritance of Copy Number Variants in Nuclear Families

PubMed Central

Palta, Priit; Kaplinski, Lauris; Nagirnaja, Liina; Veidenberg, Andres; Möls, Märt; Nelis, Mari; Esko, Tõnu; Metspalu, Andres; Laan, Maris; Remm, Maido

2015-01-01

DNA copy number variants (CNVs) that alter the copy number of a particular DNA segment in the genome play an important role in human phenotypic variability and disease susceptibility. A number of CNVs overlapping with genes have been shown to confer risk to a variety of human diseases thus highlighting the relevance of addressing the variability of CNVs at a higher resolution. So far, it has not been possible to deterministically infer the allelic composition of different haplotypes present within the CNV regions. We have developed a novel computational method, called PiCNV, which enables to resolve the haplotype sequence composition within CNV regions in nuclear families based on SNP genotyping microarray data. The algorithm allows to i) phase normal and CNV-carrying haplotypes in the copy number variable regions, ii) resolve the allelic copies of rearranged DNA sequence within the haplotypes and iii) infer the heritability of identified haplotypes in trios or larger nuclear families. To our knowledge this is the first program available that can deterministically phase null, mono-, di-, tri- and tetraploid genotypes in CNV loci. We applied our method to study the composition and inheritance of haplotypes in CNV regions of 30 HapMap Yoruban trios and 34 Estonian families. For 93.6% of the CNV loci, PiCNV enabled to unambiguously phase normal and CNV-carrying haplotypes and follow their transmission in the corresponding families. Furthermore, allelic composition analysis identified the co-occurrence of alternative allelic copies within 66.7% of haplotypes carrying copy number gains. We also observed less frequent transmission of CNV-carrying haplotypes from parents to children compared to normal haplotypes and identified an emergence of several de novo deletions and duplications in the offspring. PMID:25853576

Haplotype phasing and inheritance of copy number variants in nuclear families.

PubMed

Palta, Priit; Kaplinski, Lauris; Nagirnaja, Liina; Veidenberg, Andres; Möls, Märt; Nelis, Mari; Esko, Tõnu; Metspalu, Andres; Laan, Maris; Remm, Maido

2015-01-01

DNA copy number variants (CNVs) that alter the copy number of a particular DNA segment in the genome play an important role in human phenotypic variability and disease susceptibility. A number of CNVs overlapping with genes have been shown to confer risk to a variety of human diseases thus highlighting the relevance of addressing the variability of CNVs at a higher resolution. So far, it has not been possible to deterministically infer the allelic composition of different haplotypes present within the CNV regions. We have developed a novel computational method, called PiCNV, which enables to resolve the haplotype sequence composition within CNV regions in nuclear families based on SNP genotyping microarray data. The algorithm allows to i) phase normal and CNV-carrying haplotypes in the copy number variable regions, ii) resolve the allelic copies of rearranged DNA sequence within the haplotypes and iii) infer the heritability of identified haplotypes in trios or larger nuclear families. To our knowledge this is the first program available that can deterministically phase null, mono-, di-, tri- and tetraploid genotypes in CNV loci. We applied our method to study the composition and inheritance of haplotypes in CNV regions of 30 HapMap Yoruban trios and 34 Estonian families. For 93.6% of the CNV loci, PiCNV enabled to unambiguously phase normal and CNV-carrying haplotypes and follow their transmission in the corresponding families. Furthermore, allelic composition analysis identified the co-occurrence of alternative allelic copies within 66.7% of haplotypes carrying copy number gains. We also observed less frequent transmission of CNV-carrying haplotypes from parents to children compared to normal haplotypes and identified an emergence of several de novo deletions and duplications in the offspring.

Phase change of iron ore reduction process using EFB as reducing agent at 900-1200°C

NASA Astrophysics Data System (ADS)

Purwanto, H.; Salleh, H. M.; Rozhan, A. N.; Mohamad, A. S.; Zakiyuddin, A.

2018-04-01

Treatment of low grade iron ore involved reduction of oxygen in iron oxide by using reductant such as carbon monoxide or hydrogen gas. Presently, carboneous materials such as coke/coal are widely used as a source to provide reducing gas, but some problem arises from this material as the gas can harm the environments. Therefore, empty fruit bunch biomass from oil palm becomes an alternative to replace the usage of coke/coal as their major composition is carbon and hydrogen. The idea of replacing coke with biomass will reduce the amount of carbon dioxide release as biomass is a carbon neutral and renewable source, and at the same time abundance of waste from oil palm industries can be overcome. Therefore, the aim of this research is to upgrade the low grade iron with reducibility more than 50% being used in iron and steel making. In this research, low grade iron ore are mixed together with EFB then is making into composite pellet before being reduced at certain parameter chosen. The variables involved in this research is composition EFB (10%, 30% and 50%), temperature (1000°C, 1100°C and 1200°C) and reduction time is fixed with 30 minutes. From the experiment conducted, the highest reducibility achieved is 76.37% at temperature 1200°C. While XRD analysis shows the existence of metallic iron phase started to form at 1000°C with composition of 30% of EFB. Meanwhile, from magnetization test show that at 1200°C the highest magnetic susceptibility is achieved as the dominance phase at 1200°C is metallic phase. Therefore it is an interesting alternative to replace coke with biomass for reducing agent in upgrading low grade iron into workable ores.

Influence of surface and finite size effects on the structural and magnetic properties of nanocrystalline lanthanum strontium perovskite manganites

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

Žvátora, Pavel; Veverka, Miroslav; Veverka, Pavel

2013-08-15

Syntheses of nanocrystalline perovskite phases of the general formula La{sub 1−x}Sr{sub x}MnO{sub 3+δ} were carried out employing sol–gel technique followed by thermal treatment at 700–900 °C under oxygen flow. The prepared samples exhibit a rhombohedral structure with space group R3{sup ¯}c in the whole investigated range of composition 0.20≤x≤0.45. The studies were aimed at the chemical composition including oxygen stoichiometry and extrinsic properties, i.e. size of the particles, both influencing the resulting structural and magnetic properties. The oxygen stoichiometry was determined by chemical analysis revealing oxygen excess in most of the studied phases. The excess was particularly high for themore » samples with the smallest crystallites (12–28 nm) while comparative bulk materials showed moderate non-stoichiometry. These differences are tentatively attributed to the surface effects in view of the volume fraction occupied by the upper layer whose atomic composition does not comply with the ideal bulk stoichiometry. - Graphical abstract: Evolution of the particle size with annealing temperature in the nanocrystalline La{sub 0.70}Sr{sub 0.30}MnO{sub 3+δ} phase. Display Omitted - Highlights: • The magnetic behaviour of nanocrystalline La{sub 1−x}Sr{sub x}MnO{sub 3+δ} phases was analyzed on the basis of their crystal structure, chemical composition and size of the particles. • Their Curie temperature and magnetization are markedly affected by finite size and surface effects. • The oxygen excess observed in the La{sub 1−x}Sr{sub x}MnO{sub 3+δ} nanoparticles might be generated by the surface layer with deviated oxygen stoichiometry.« less

Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

NASA Astrophysics Data System (ADS)

Smith, Robert A.; Nelson, Luke J.; Mienczakowski, Martin J.

2018-04-01

Ultrasonic 3D characterization of ply-level features in layered composites, such as out-of-plane wrinkles and ply drops, is now possible with carefully applied analytic-signal analysis. Study of instantaneous amplitude, phase and frequency in the ultrasonic response has revealed some interesting effects, which become more problematic for 3D characterization as the inter-ply resin-layer thicknesses increase. In modern particle-toughened laminates, the thicker resin layers cause phase singularities to be observed; these are locations where the instantaneous amplitude is zero, so the instantaneous phase is undefined. The depth at which these occur has been observed experimentally to vary with resin- layer thickness, such that a phase-singularity surface is formed; beyond this surface, the ultrasonic response is reduced and significantly more difficult to interpret, so a method for removing the effect would be advantageous. The underlying physics has been studied using an analytical one-dimensional multi-layer model. This has been sufficient to determine that the cause is linked to a phononic band gap in the ultrasound transmitted through multiple equally-spaced partial reflectors. As a result, the phase singularity also depends on input-pulse center frequency and bandwidth. Various methods for overcoming the confusing effects in the data have been proposed and subsequently investigated using the analytical model. This paper will show experimental and modelled evidence of phase-singularities and phase-singularity surfaces, as well as the success of methods for reducing their effects.

The correlation of local deformation and stress-assisted local phase transformations in MMC foams

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

Berek, H., E-mail: harry.berek@ikgb.tu-freiberg.de; Ballaschk, U.; Aneziris, C.G.

2015-09-15

Cellular structures are of growing interest for industry, and are of particular importance for lightweight applications. In this paper, a special case of metal matrix composite foams (MMCs) is investigated. The investigated foams are composed of austenitic steel exhibiting transformation induced plasticity (TRIP) and magnesia partially stabilized zirconia (Mg-PSZ). Both components exhibit martensitic phase transformation during deformation, thus generating the potential for improved mechanical properties such as strength, ductility, and energy absorption capability. The aim of these investigations was to show that stress-assisted phase transformations within the ceramic reinforcement correspond to strong local deformation, and to determine whether they canmore » trigger martensitic phase transformations in the steel matrix. To this end, in situ interrupted compression experiments were performed in an X-ray computed tomography device (XCT). By using a recently developed registration algorithm, local deformation could be calculated and regions of interest could be defined. Corresponding cross sections were prepared and used to analyze the local phase composition by electron backscatter diffraction (EBSD). The results show a strong correlation between local deformation and phase transformation. - Graphical abstract: Display Omitted - Highlights: • In situ compressive deformation on MMC foams was performed in an XCT. • Local deformation fields and their gradient amplitudes were estimated. • Cross sections were manufactured containing defined regions of interest. • Local EBSD phase analysis was performed. • Local deformation and local phase transformation are correlated.« less

Fine Structure in Multi-Phase Zr8Ni21-Zr7Ni10-Zr2Ni7 Alloy Revealed by Transmission Electron Microscope

PubMed Central

Shen, Haoting; Bendersky, Leonid A.; Young, Kwo; Nei, Jean

2015-01-01

The microstructure of an annealed alloy with a Zr8Ni21 composition was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of three phases, Zr8Ni21, Zr2Ni7, and Zr7Ni10, was confirmed by SEM/X-ray energy dispersive spectroscopy compositional mapping and TEM electron diffraction. Distribution of the phases and their morphology can be linked to a multi-phase structure formed by a sequence of reactions: (1) L → Zr2Ni7 + L’; (2) peritectic Zr2Ni7 + L’ → Zr2Ni7 + Zr8Ni21 + L”; (3) eutectic L” → Zr8Ni21 + Zr7Ni10. The effect of annealing at 960 °C, which was intended to convert a cast structure into a single-phase Zr8Ni21 structure, was only moderate and the resulting alloy was still multi-phased. TEM and crystallographic analysis of the Zr2Ni7 phase show a high density of planar (001) defects that were explained as low-energy boundaries between rotational variants and stacking faults. The crystallographic features arise from the pseudo-hexagonal structure of Zr2Ni7. This highly defective Zr2Ni7 phase was identified as the source of the broad X-ray diffraction peaks at around 38.4° and 44.6° when a Cu-K was used as the radiation source. PMID:28793460

Analytical methods to characterize heterogeneous raw material for thermal spray process: cored wire Inconel 625

NASA Astrophysics Data System (ADS)

Lindner, T.; Bonebeau, S.; Drehmann, R.; Grund, T.; Pawlowski, L.; Lampke, T.

2016-03-01

In wire arc spraying, the raw material needs to exhibit sufficient formability and ductility in order to be processed. By using an electrically conductive, metallic sheath, it is also possible to handle non-conductive and/or brittle materials such as ceramics. In comparison to massive wire, a cored wire has a heterogeneous material distribution. Due to this fact and the complex thermodynamic processes during wire arc spraying, it is very difficult to predict the resulting chemical composition in the coating with sufficient accuracy. An Inconel 625 cored wire was used to investigate this issue. In a comparative study, the analytical results of the raw material were compared to arc sprayed coatings and droplets, which were remelted in an arc furnace under argon atmosphere. Energy-dispersive X-ray spectroscopy (EDX) and X-ray fluorescence (XRF) analysis were used to determine the chemical composition. The phase determination was performed by X-ray diffraction (XRD). The results were related to the manufacturer specifications and evaluated in respect to differences in the chemical composition. The comparison between the feedstock powder, the remelted droplets and the thermally sprayed coatings allows to evaluate the influence of the processing methods on the resulting chemical and phase composition.

Improved irradiation tolerance of reactive gas pulse sputtered TiN coatings with a hybrid architecture of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Liang, Wei; Yang, Jijun; Zhang, Feifei; Lu, Chenyang; Wang, Lumin; Liao, Jiali; Yang, Yuanyou; Liu, Ning

2018-04-01

This study investigates the improved irradiation tolerance of reactive gas pulse (RGP) sputtered TiN coatings which has hybrid architecture of multilayered and compositionally graded structures. The multilayered RGP-TiN coating is composed of hexagonal close-packed Ti phase and face-centred cubic TiN phase sublayers, where the former sublayer has a compositionally graded structure and the latter one maintains constant stoichiometric atomic ratio of Ti:N. After 100 keV He ion irradiation, the RGP-TiN coating exhibits improved irradiation resistance compared with its single layered (SL) counterpart. The size and density of He bubbles are smaller in the RGP-TiN coating than in the SL-TiN coating. The irradiation-induced surface blistering of the coatings shows a similar tendency. Meanwhile, the irradiation hardening and adhesion strength of the RGP-TiN coatings were not greatly affected by He irradiation. Moreover, the irradiation damage tolerance of the coatings can be well tuned by changing the undulation period number of N2 gas flow rate. Detailed analysis suggested that this improved irradiation tolerance could be related to the combined contribution of the multilayered and compositionally graded structures.

Determination of pKa values of some antipsychotic drugs by HPLC--correlations with the Kamlet and taft solvatochromic parameters and HPLC analysis in dosage forms.

PubMed

Sanli, Senem; Akmese, Bediha; Altun, Yuksel

2013-01-01

In this study, ionization constant (pKa) values were determined by using the dependence of the retention factor on the pH of the mobile phase for four ionizable drugs, namely, risperidone (RI), clozapine (CL), olanzapine (OL), and sertindole (SE). The effect of the mobile phase composition on the pKa was studied by measuring the pKa at different acetonitrile-water mixtures in an HPLC-UV method. To explain the variation of the pKa values obtained over the whole composition range studied, the quasi-lattice quasi-chemical theory of preferential solvation was applied. The pKa values of drugs were correlated with the Kamlet and Taft solvatochromic parameters. Kamlet and Taft's general equation was reduced to two terms by using combined factor analysis and target factor analysis in these mixtures: the independent term and the hydrogen-bond donating ability a. The HPLC-UV method was successfully applied for the determination of RI, OL, and SE in pharmaceutical dosage forms. CL was chosen as an internal standard. Additionally, the repeatability, reproducibility, selectivity, precision, and accuracy of the method in all media were investigated and calculated.

Modification of the sample's surface of hypereutectic silumin by pulsed electron beam

NASA Astrophysics Data System (ADS)

Rygina, M. E.; Ivanov, Yu F.; Lasconev, A. P.; Teresov, A. D.; Cherenda, N. N.; Uglov, V. V.; Petricova, E. A.; Astashinskay, M. V.

2016-04-01

The article presents the results of the analysis of the elemental and phase composition, defect substructures. It demonstrates strength and tribological characteristics of the aluminium-silicon alloy of the hypereutectic composition in the cast state and after irradiation with a high-intensity pulsed electron beam of a submillisecond exposure duration (a Solo installation, Institute of High Current Electrons of the Siberian Branch of the Russian Academy of Sciences). The research has been conducted using optical and scanning electron microscopy, and the X-ray phase analysis. Mechanical properties have been characterized by microhardness, tribological properties - by wear resistance and the friction coefficient value. Irradiation of silumin with the high-intensity pulsed electron beam has led to the modification of the surface layer up to 1000 microns thick. The surface layer with the thickness of up to 100 microns is characterized by melting of all phases present in the alloy; subsequent highspeed crystallization leads to the formation of a submicro- and nanocrystalline structure in this layer. The hardness of the modified layer decreases with the increasing distance from the surface exposure. The hardness of the surface layer is more than twice the hardness of cast silumin. Durability of silumin treated with a high intensity electron beam is ≈ 1, 2 times as much as the wear resistance of the cast material.

Structure, phases, and mechanical response of Ti-alloy bioactive glass composite coatings.

PubMed

Nelson, G M; Nychka, J A; McDonald, A G

2014-03-01

Porous titanium alloy-bioactive glass composite coatings were manufactured via the flame spray deposition process. The porous coatings, targeted for orthodontic and bone-fixation applications, were made from bioactive glass (45S5) powder blended with either commercially pure titanium (Cp-Ti) or Ti-6Al-4V alloy powder. Two sets of spray conditions, two metallic particle size distributions, and two glass particle size distributions were used for this study. Negative control coatings consisting of pure Ti-6Al-4V alloy or Cp-Ti were sprayed under both conditions. The as-sprayed coatings were characterized through quantitative optical cross-sectional metallography, X-ray diffraction (XRD), and ASTM Standard C633 tensile adhesion testing. Determination of the porosity and glassy phase distribution was achieved by using image analysis in accordance with ASTM Standard E2109. Theoretical thermodynamic and heat transfer modeling was conducted to explain experimental observations. Thermodynamic modeling was performed to estimate the flame temperature and chemical environment for each spray condition and a lumped capacitance heat transfer model was developed to estimate the temperatures attained by each particle. These models were used to establish trends among the choice of alloy, spray condition, and particle size distribution. The deposition parameters, alloy composition, and alteration of the feedstock powder size distribution had a significant effect on the coating microstructure, porosity, phases present, mechanical response, and theoretical particle temperatures that were attained. The most promising coatings were the Ti-6Al-4V-based composite coatings, which had bond strength of 20±2MPa (n=5) and received reinforcement and strengthening from the inclusion of a glassy phase. It was shown that the use of the Ti-6Al-4V-bioactive glass composite coatings may be a superior choice due to the possible osteoproductivity from the bioactive glass, the potential ability to support tissue ingrowth and vascular tissue, and the comparable strength to similar coatings. Copyright © 2013 Elsevier B.V. All rights reserved.

Exploring Chondrule and CAI Rims Using Micro- and Nano-Scale Petrological and Compositional Analysis

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Perez-Huerta, A.; Leitner, J.; Vollmer, C.

2017-12-01

As the major components within chondrites, chondrules (mm-sized droplets of quenched silicate melt) and calcium-aluminum-rich inclusions (CAI, refractory) represent the most abundant and the earliest materials that solidified from the solar nebula. However, the exact formation mechanisms of these clasts, and whether these processes are related, remains unconstrained, despite extensive petrological and compositional study. By taking advantage of recent advances in nano-scale tomographical techniques, we have undertaken a combined micro- and nano-scale study of CAI and chondrule rim morphologies, to investigate their formation mechanisms. The target lithologies for this research are Wark-Lovering rims (WLR), and fine-grained rims (FGR) around CAIs and chondrules respectively, present within many chondrites. The FGRs, which are up to 100 µm thick, are of particular interest as recent studies have identified presolar grains within them. These grains predate the formation of our Solar System, suggesting FGR formation under nebular conditions. By contrast, WLRs are 10-20 µm thick, made of different compositional layers, and likely formed by flash-heating shortly after CAI formation, thus recording nebular conditions. A detailed multi-scale study of these respective rims will enable us to better understand their formation histories and determine the potential for commonality between these two phases, despite reports of an observed formation age difference of up to 2-3 Myr. We are using a combination of complimentary techniques on our selected target areas: 1) Micro-scale characterization using standard microscopic and compositional techniques (SEM-EBSD, EMPA); 2) Nano-scale characterization of structures using transmission electron microscopy (TEM) and elemental, isotopic and tomographic analysis with NanoSIMS and atom probe tomography (APT). Preliminary nano-scale APT analysis of FGR morphologies within the Allende carbonaceous chondrite has successfully discerned complex chondritic mineralogies and compositional differences across boundaries, which is one of the first applications of in-situ APT techniques to chondrites. Further data reduction will allow us to characterize the exact phases present, and further chondrite analyses are in progress.

Chemical Species, Micromorphology, and XRD Fingerprint Analysis of Tibetan Medicine Zuotai Containing Mercury

PubMed Central

Li, Cen; Yang, Hongxia; Xiao, Yuancan; Zhandui; Sanglao; Wang, Zhang; Ladan, Duojie; Bi, Hongtao

2016-01-01

Zuotai (gTso thal) is one of the famous drugs containing mercury in Tibetan medicine. However, little is known about the chemical substance basis of its pharmacodynamics and the intrinsic link of different samples sources so far. Given this, energy dispersive spectrometry of X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and powder X-ray diffraction (XRD) were used to assay the elements, micromorphology, and phase composition of nine Zuotai samples from different regions, respectively; the XRD fingerprint features of Zuotai were analyzed by multivariate statistical analysis. EDX result shows that Zuotai contains Hg, S, O, Fe, Al, Cu, and other elements. SEM and AFM observations suggest that Zuotai is a kind of ancient nanodrug. Its particles are mainly in the range of 100–800 nm, which commonly further aggregate into 1–30 μm loosely amorphous particles. XRD test shows that β-HgS, S8, and α-HgS are its main phase compositions. XRD fingerprint analysis indicates that the similarity degrees of nine samples are very high, and the results of multivariate statistical analysis are broadly consistent with sample sources. The present research has revealed the physicochemical characteristics of Zuotai, and it would play a positive role in interpreting this mysterious Tibetan drug. PMID:27738409

Chemical Species, Micromorphology, and XRD Fingerprint Analysis of Tibetan Medicine Zuotai Containing Mercury.

PubMed

Li, Cen; Yang, Hongxia; Du, Yuzhi; Xiao, Yuancan; Zhandui; Sanglao; Wang, Zhang; Ladan, Duojie; Bi, Hongtao; Wei, Lixin

2016-01-01

Zuotai ( gTso thal ) is one of the famous drugs containing mercury in Tibetan medicine. However, little is known about the chemical substance basis of its pharmacodynamics and the intrinsic link of different samples sources so far. Given this, energy dispersive spectrometry of X-ray (EDX), scanning electron microscopy (SEM), atomic force microscopy (AFM), and powder X-ray diffraction (XRD) were used to assay the elements, micromorphology, and phase composition of nine Zuotai samples from different regions, respectively; the XRD fingerprint features of Zuotai were analyzed by multivariate statistical analysis. EDX result shows that Zuotai contains Hg, S, O, Fe, Al, Cu, and other elements. SEM and AFM observations suggest that Zuotai is a kind of ancient nanodrug. Its particles are mainly in the range of 100-800 nm, which commonly further aggregate into 1-30  μ m loosely amorphous particles. XRD test shows that β -HgS, S 8 , and α -HgS are its main phase compositions. XRD fingerprint analysis indicates that the similarity degrees of nine samples are very high, and the results of multivariate statistical analysis are broadly consistent with sample sources. The present research has revealed the physicochemical characteristics of Zuotai , and it would play a positive role in interpreting this mysterious Tibetan drug.

Thermal analysis of 3-mol%-yttria-stabilized tetragonal zirconia powder doped with copper oxide

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

Seidensticker, J.R.; Mayo, M.J.

Thermal analysis was performed upon 3-mol%-yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) which had been doped with CuO using an aqueous adsorption technique. Cyclic differential thermal analysis (DTA) scans indicated that the CuO present on the powder surfaces first transforms to Cu{sub 2}O and then melts. The molten Cu{sub 2}O then reacts with yttria at the powder surfaces to form a new phase containing Y, Cu, and O. Because Y takes time to diffuse to the particle surfaces, the apparent melting point of this new phase appears at higher temperatures in initial DTA scans than in subsequent scans. Vaporization of the moltenmore » copper-oxide-rich phase at the temperatures studied causes a gradual shift in composition from Y{sub 2}Cu{sub 4}O{sub 5} to the less copper-rich Y{sub 2}Cu{sub 2}O{sub 5} phase. The presence of the Y{sub 2}Cu{sub 2}O{sub 5} phase in CuO-doped 3Y-TZP allows for previous sintering and superplasticity results to be explained.« less

Design/Analysis of Metal/Composite Bonded Joints for Survivability at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Bartoszyk, Andrew E.

2004-01-01

A major design and analysis challenge for the JWST ISM structure is the metal/composite bonded joints that will be required to survive down to an operational ultra-low temperature of 30K (-405 F). The initial and current baseline design for the plug-type joint consists of a titanium thin walled fitting (1-3mm thick) bonded to the interior surface of an M555/954-6 composite truss square tube with an axially stiff biased lay-up. Metallic fittings are required at various nodes of the truss structure to accommodate instrument and lift-point bolted interfaces. Analytical experience and design work done on metal/composite bonded joints at temperatures below liquid nitrogen are limited and important analysis tools, material properties, and failure criteria for composites at cryogenic temperatures are virtually nonexistent. Increasing the challenge is the difficulty in testing for these required tools and parameters at 30K. A preliminary finite element analysis shows that failure due to CTE mismatch between the biased composite and titanium or aluminum is likely. Failure is less likely with Invar, however an initial mass estimate of Invar fittings demonstrates that Invar is not an automatic alternative. In order to gain confidence in analyzing and designing the ISM joints, a comprehensive joint development testing program has been planned and is currently running. The test program is designed for the correlation of the analysis methodology, including tuning finite element model parameters, and developing a composite failure criterion for the effect of multi-axial composite stresses on the strength of a bonded joint at 30K. The testing program will also consider stress mitigation using compliant composite layers and potential strength degradation due to multiple thermal cycles. Not only will the finite element analysis be correlated to the test data, but the FEA will be used to guide the design of the test. The first phase of the test program has been completed and the preliminary analysis has been revisited based on the test data In this work, we present an overview of the test plan, results today, and resulting design improvements.

Features of the phase composition and morphology of the particles of sialon synthesized from silicon and aluminum nitrides

NASA Astrophysics Data System (ADS)

Ivicheva, S. N.; Lysenkov, A. S.; Ovsyannikov, N. A.; Titov, D. D.; Kargin, Yu F.

2018-04-01

The phase composition and morphological features of sialons were studied under the same conditions of firing (duration, temperature) using different initial components, silicon nitride, aluminum nitride, and a mixture of silicon nitrides and aluminum with the application of nitrides of the corresponding oxide (aluminum or silicon) sol-gel method. The effect of the initial reagents composition on the phase composition of the final product and the morphological features of the sialon powders obtained in a single firing step in a nitrogen atmosphere is shown.

Oxidation sulfidation resistance of Fe-Cr-Ni alloys

DOEpatents

Natesan, Ken; Baxter, David J.

1984-01-01

High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1-8 wt. % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500.degree.-1000.degree. C.

Learning in the Absence of Experience-Dependent Regulation of NMDAR Composition

ERIC Educational Resources Information Center

Lebel, David; Sidhu, Nishchal; Barkai, Edi; Quinlan, Elizabeth M.

2006-01-01

Olfactory discrimination (OD) learning consists of two phases: an initial N-methyl-d-aspartate (NMDA) receptor--sensitive rule-learning phase, followed by an NMDA receptor (NMDAR)--insensitive pair-learning phase. The rule-learning phase is accompanied by changes in the composition and function of NMDARs at synapses in the piriform cortex,…

Development and Optimization of Tailored Composite TBC Design Architectures for Improved Erosion Durability

NASA Astrophysics Data System (ADS)

Schmitt, Michael P.; Schreiber, Jeremy M.; Rai, Amarendra K.; Eden, Timothy J.; Wolfe, Douglas E.

2017-08-01

Rare-earth pyrochlores, RE2Zr2O7, have been identified as potential thermal barrier coating (TBC) materials due to their attractive thermal properties and CMAS resistance. However, they possess a low fracture toughness which results in poor erosion durability/foreign object damage resistance. This research focuses on the development of tailored composite air plasma spray (APS) TBC design architectures utilizing a t' Low-k secondary toughening phase (ZrO2-2Y2O3-1Gd2O3-1Yb2O3; mol.%) to enhance the erosion durability of a hyper-stoichiometric pyrochlore, NZO (ZrO2-25Nd2O3-5Y2O3-5Yb2O3; mol.%). In this study, composite coatings have been deposited with 30, 50, and 70% (wt.%) t' Low-k toughening phase in a horizontally aligned lamellar morphology which enhances the toughening response of the coating. The coatings were characterized via SEM and XRD and were tested for erosion durability before and after isothermal heat treatment at 1100 °C. Analysis with mixing laws indicated improved erosion performance; however, a lack of long-term thermal stability was shown via isothermal heat treatments at 1316 °C. An impact stress analysis was performed using finite element analysis of a coating cross section, representing the first microstructurally realistic study of mechanical properties of TBCs with the results correlating well with observed behavior.

Investigation of (Ti-Zr-Hf-V-Nb)N Multicomponent Nanostructured Coatings before and after Thermal Annealing by Nuclear Physics Methods of Analysis

NASA Astrophysics Data System (ADS)

Pogrebnjak, A. D.; Beresnev, V. M.; Bondar', A. V.; Kaverin, M. V.; Ponomarev, A. G.

2013-10-01

(Ti-Zr-Hf-V-Nb)N multicomponent nanostructured coatings with thickness of 1.0-1.4 μm synthesized by the method of cathode arc-vapor deposition at temperatures of 250-300°С are investigated by various mutually complementary methods of elemental structural analysis using slow positron beams (SPB), proton microbeam based particle-induced x-ray emission (μ-PIXE), energy-dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) analyses based on electron micro- and nanobeams, x-ray diffraction (XRD) method of phase structural analysis, and the "a-sin2φ" method of measuring a stressed-strained state (x-ray tensometry). The elemental composition, microstructure, residual stress in nanograins, profiles of defect and atom distributions with depth and over the coating surface in 3D-representation are studied for these coatings, and their phase composition, severely strained state, and composition of coatings before and after annealing at Tann = 600°С for annealing time τ = 30 min are investigated. It is demonstrated that the oxidation resistance of the examined coatings can be significantly increased by high-temperature annealing that leads to the formation of elastic severely strained compression state of the coating. Redistribution of elements and defects, their segregation near the interface boundaries and around grains and subgrains in the process of thermostimulated diffusion, and termination of spinodal segregation without considerable change of the average nanograin size are revealed.