Dry powder mixes comprising phase change materials

DOEpatents

Salyer, I.O.

1995-12-26

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figs.

Dry powder mixes comprising phase change materials

DOEpatents

Salyer, I.O.

1994-12-06

A free flowing, conformable powder-like mix of silica particles and a phase change material (PCM) is provided. The silica particles have a critical size of about 0.005 to about 0.025 microns and the PCM must be added to the silica in an amount of 75% or less PCM per combined weight of silica and PCM. The powder-like mix can be used in tableware items, medical wraps, tree wraps, garments, quilts and blankets, and particularly in applications for heat protection for heat sensitive items, such as aircraft flight recorders, and for preventing brake fade in automobiles, buses, trucks and aircraft. 3 figures.

Preparation, characterization and application of a reversed phase liquid chromatography/hydrophilic interaction chromatography mixed-mode C18-DTT stationary phase.

PubMed

Wang, Qing; Long, Yao; Yao, Lin; Xu, Li; Shi, Zhi-Guo; Xu, Lanying

2016-01-01

A mixed-mode chromatographic stationary phase, C18-DTT (dithiothreitol) silica (SiO2) was prepared through "thiol-ene" click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen, guanine, tetrandrine and nicotinic acid) in the range of 1.82-3.72% and 0.85-1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids, alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons. It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase. Copyright © 2015 Elsevier B.V. All rights reserved.

Electromagnetic mixed waste processing system for asbestos decontamination

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

Kasevich, R.S.; Vaux, W.; Ulerich, N.

The overall objective of this three-phase program is to develop an integrated process for treating asbestos-containing material that is contaminated with radioactive and hazardous constituents. The integrated process will attempt to minimize processing and disposal costs. The objectives of Phase 1 were to establish the technical feasibility of asbestos decomposition, inorganic radionuclide nd heavy metal removal, and organic volatilization. Phase 1 resulted in the successful bench-scale demonstration of the elements required to develop a mixed waste treatment process for asbestos-containing material (ACM) contaminated with radioactive metals, heavy metals, and organics. Using the Phase 1 data, a conceptual process was developed.more » The Phase 2 program, currently in progress, is developing an integrated system design for ACM waste processing. The Phase 3 program will target demonstration of the mixed waste processing system at a DOE facility. The electromagnetic mixed waste processing system employs patented technologies to convert DOE asbestos to a non-hazardous, radionuclide-free, stable waste. The dry, contaminated asbestos is initially heated with radiofrequency energy to remove organic volatiles. Second,the radionuclides are removed by solvent extraction coupled with ion exchange solution treatment. Third, the ABCOV method converts the asbestos to an amorphous silica suspension at low temperature (100{degrees}C). Finally the amorphous silica is solidified for disposal.« less

Laboratory Evaluation of Remediation Alternatives for U.S. Coast Guard Small Arms Firing Ranges

DTIC Science & Technology

1999-11-01

S) is an immobilization process that involves the mixing of a contaminated soil with a binder material to enhance the physical and chemical...samples were shipped to WES for laboratory analysis. Phase III: Homogenization of the Bulk Samples. Each of the bulk samples was separately mixed to...produce uniform samples for testing. These mixed bulk soil samples were analyzed for metal content. Phase IV: Characterization of the Bulk Soils

Thermal characteristics of non-edible oils as phase change materials candidate to application of air conditioning chilled water system

NASA Astrophysics Data System (ADS)

Irsyad, M.; Indartono, Y. S.; Suwono, A.; Pasek, A. D.

2015-09-01

The addition of phase change material in the secondary refrigerant has been able to reduce the energy consumption of air conditioning systems in chilled water system. This material has a high thermal density because its energy is stored as latent heat. Based on material melting and freezing point, there are several non-edible oils that can be studied as a phase change material candidate for the application of chilled water systems. Forests and plantations in Indonesia have great potential to produce non-edible oil derived from the seeds of the plant, such as; Calophyllum inophyllum, Jatropha curcas L, and Hevea braziliensis. Based on the melting temperature, these oils can further studied to be used as material mixing in the secondary refrigerant. Thermal characteristics are obtained from the testing of T-history, Differential Scanning Calorimetric (DSC) and thermal conductivity materials. Test results showed an increase in the value of the latent heat when mixed with water with the addition of surfactant. Thermal characteristics of each material of the test results are shown completely in discussion section of this article.

Research on Nondestructive Testing.

DTIC Science & Technology

1981-11-01

account of two phase materials and has been used to describe results ootained in carbon steels . 2. Acoustic Attenuation in Steels with Mixed Ferrite ...to 13000C where the austenite phase is stable. During cooling to room temperature, the austenite transforms to pearlite and ferrite (slow cooling...20 1. Introduction ..... .................................. 20 2. Acoustic Attenuation in Steels with Mixed Ferrite -Pearlite

Microstructural Damage During High-Strain Torsion Experiments on Calcite-Anhydrite Aggregates

NASA Astrophysics Data System (ADS)

Cross, A. J.; Skemer, P. A.

2016-12-01

Ductile shear zones play a critical role in localising deformation in the Earth's crust and mantle. Severe grain size reduction - a ubiquitous feature of natural mylonites - is commonly thought to cause strain weakening via a transition to grain size sensitive deformation mechanisms. Although grain size reduction is modulated by grain growth in single-phase aggregates, grain boundary pinning in well-mixed poly-phase composites can inhibit grain growth, leading to microstructural `damage' which is likely a critical element of strain localization in the lithosphere. While dynamic recrystallization has been widely explored in rock mechanics and materials science, the mechanisms behind phase-mixing remain poorly understood. In this contribution we present results from high-strain, deformation experiments on calcite-anhydrite composites. Experiments were conducted in torsion at T = 500-700°C and P 1.5 GPa, using the new Large Volume Torsion (LVT) solid-medium apparatus, to shear strains of 0.5-30. As shear strain increases, progressive thinning and necking of initially large (≤ 1 mm) calcite domains is observed, resulting in an increase in the proportion of interphase boundaries. Grain-size is negatively correlated with the fraction of interphase boundaries, such that calcite grains in well-mixed regions are significantly smaller than those in single-phase domains. Crucially, progressive deformation leads to a reduction in grain-size beyond the lower limit established by the grain size piezometer for mono-phase calcite, implying microstructural damage. These data therefore demonstrate continued microstructural evolution in two-phase composites that is not possible in single-phase aggregates. These observations mark a new `geometric' mechanism for phase mixing, complementing previous models for phase mixing involving chemical reactions, material diffusion, and/or grain boundary sliding.

Apparatus for the processing of solid mixed waste containing radioactive and hazardous materials

DOEpatents

Gotovchikov, Vitaly T.; Ivanov, Alexander V.; Filippov, Eugene A.

1999-03-16

Apparatus for the continuous heating and melting of a solid mixed waste bearing radioactive and hazardous materials to form separate metallic, slag and gaseous phases for producing compact forms of the waste material to facilitate disposal includes a copper split water-cooled (cold) crucible as a reaction vessel for receiving the waste material. The waste material is heated by means of the combination oaf plasma torch directed into the open upper portion of the cold crucible and an electromagnetic flux produced by induction coils disposed about the crucible which is transparent to electromagnetic fields. A metallic phase of the waste material is formed in a lower portion of the crucible and is removed in the form of a compact ingot suitable for recycling and further processing. A glass-like, non-metallic slag phase containing radioactive elements is also formed in the crucible and flows out of the open upper portion of the crucible into a slag ingot mold for disposal. The decomposition products of the organic and toxic materials are incinerated and converted to environmentally safe gases in the melter.

Processing of solid mixed waste containing radioactive and hazardous materials

DOEpatents

Gotovchikov, Vitaly T.; Ivanov, Alexander V.; Filippov, Eugene A.

1998-05-12

Apparatus for the continuous heating and melting of a solid mixed waste bearing radioactive and hazardous materials to form separate metallic, slag and gaseous phases for producing compact forms of the waste material to facilitate disposal includes a copper split water-cooled (cold) crucible as a reaction vessel for receiving the waste material. The waste material is heated by means of the combination of a plasma torch directed into the open upper portion of the cold crucible and an electromagnetic flux produced by induction coils disposed about the crucible which is transparent to electromagnetic fields. A metallic phase of the waste material is formed in a lower portion of the crucible and is removed in the form of a compact ingot suitable for recycling and further processing. A glass-like, non-metallic slag phase containing radioactive elements is also formed in the crucible and flows out of the open upper portion of the crucible into a slag ingot mold for disposal. The decomposition products of the organic and toxic materials are incinerated and converted to environmentally safe gases in the melter.

Apparatus for the processing of solid mixed waste containing radioactive and hazardous materials

DOEpatents

Gotovchikov, V.T.; Ivanov, A.V.; Filippov, E.A.

1999-03-16

Apparatus for the continuous heating and melting of a solid mixed waste bearing radioactive and hazardous materials to form separate metallic, slag and gaseous phases for producing compact forms of the waste material to facilitate disposal includes a copper split water-cooled (cold) crucible as a reaction vessel for receiving the waste material. The waste material is heated by means of the combination of a plasma torch directed into the open upper portion of the cold crucible and an electromagnetic flux produced by induction coils disposed about the crucible which is transparent to electromagnetic fields. A metallic phase of the waste material is formed in a lower portion of the crucible and is removed in the form of a compact ingot suitable for recycling and further processing. A glass-like, non-metallic slag phase containing radioactive elements is also formed in the crucible and flows out of the open upper portion of the crucible into a slag ingot mold for disposal. The decomposition products of the organic and toxic materials are incinerated and converted to environmentally safe gases in the melter. 6 figs.

Processing of solid mixed waste containing radioactive and hazardous materials

DOEpatents

Gotovchikov, V.T.; Ivanov, A.V.; Filippov, E.A.

1998-05-12

Apparatus for the continuous heating and melting of a solid mixed waste bearing radioactive and hazardous materials to form separate metallic, slag and gaseous phases for producing compact forms of the waste material to facilitate disposal includes a copper split water-cooled (cold) crucible as a reaction vessel for receiving the waste material. The waste material is heated by means of the combination of a plasma torch directed into the open upper portion of the cold crucible and an electromagnetic flux produced by induction coils disposed about the crucible which is transparent to electromagnetic fields. A metallic phase of the waste material is formed in a lower portion of the crucible and is removed in the form of a compact ingot suitable for recycling and further processing. A glass-like, non-metallic slag phase containing radioactive elements is also formed in the crucible and flows out of the open upper portion of the crucible into a slag ingot mold for disposal. The decomposition products of the organic and toxic materials are incinerated and converted to environmentally safe gases in the melter. 6 figs.

Study on the light-color mixing of rare earth luminescent materials for anti-counterfeiting application

NASA Astrophysics Data System (ADS)

Zhang, Jishu; Zhang, Yingzi; Tao, Jin; Zhu, Yanan

2018-04-01

In order to find out the light color mixing mechanism of rare earth luminescent materials used in anti-counterfeiting fibers, we prepared three kinds of rare earth luminescent materials according to RGB tri-primary color, and mixed it together to form different mixtures in certain proportion. The phase structures of the luminescent material monomers were measured by x-ray diffractometer. The photochromic properties of the luminescent materials were tested and analyzed by fluorescence spectrophotometer. The results show that the light color mixing was consistent with the blending principle of additive color, but not the same because of the photochromic properties of rare earth luminescent materials, and we explored the reasons in the light wavelength and intensity. It was found that the enhancement of the luminescence intensity of the mixture on account of the superimposing of luminescence.

Time-reversal and rotation symmetry breaking superconductivity in Dirac materials

NASA Astrophysics Data System (ADS)

Chirolli, Luca; de Juan, Fernando; Guinea, Francisco

2017-05-01

We consider mixed symmetry superconducting phases in Dirac materials in the odd-parity channel, where pseudoscalar and vector order parameters can coexist due to their similar critical temperatures when attractive interactions are of a finite range. We show that the coupling of these order parameters to unordered magnetic dopants favors the condensation of time-reversal symmetry breaking (TRSB) phases, characterized by a condensate magnetization, rotation symmetry breaking, and simultaneous ordering of the dopant moments. We find a rich phase diagram of mixed TRSB phases characterized by peculiar bulk quasiparticles, with Weyl nodes and nodal lines, and distinctive surface states. These findings are consistent with recent experiments on NbxBi2Se3 that report evidence of point nodes, nematicity, and TRSB superconductivity induced by Nb magnetic moments.

Effect of crystallographic orientations of grains on the global mechanical properties of steel sheets by depth sensing indentation

NASA Astrophysics Data System (ADS)

Burik, P.; Pesek, L.; Kejzlar, P.; Andrsova, Z.; Zubko, P.

2017-01-01

The main idea of this work is using a physical model to prepare a virtual material with required properties. The model is based on the relationship between the microstructure and mechanical properties. The macroscopic (global) mechanical properties of steel are highly dependent upon microstructure, crystallographic orientation of grains, distribution of each phase present, etc... We need to know the local mechanical properties of each phase separately in multiphase materials. The grain size is a scale, where local mechanical properties are responsible for the behavior. Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. The aim of this experimental investigation is: (i) to prove how the mixing rule works for local mechanical properties (indentation hardness HIT) in microstructure scale using the DSI technique on steel sheets with different microstructure; (ii) to compare measured global properties with properties achieved by mixing rule; (iii) to analyze the effect of crystallographic orientations of grains on the mixing rule.

Rationalizing the light-induced phase separation of mixed halide organic-inorganic perovskites.

PubMed

Draguta, Sergiu; Sharia, Onise; Yoon, Seog Joon; Brennan, Michael C; Morozov, Yurii V; Manser, Joseph S; Kamat, Prashant V; Schneider, William F; Kuno, Masaru

2017-08-04

Mixed halide hybrid perovskites, CH 3 NH 3 Pb(I 1-x Br x ) 3 , represent good candidates for low-cost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material's optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodide-rich phases. It additionally explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.Mixed halide hybrid perovskites possess tunable band gaps, however, under illumination they undergo phase separation. Using spectroscopic measurements and theoretical modelling, Draguta and Sharia et al. quantitatively rationalize the microscopic processes that occur during phase separation.

Persistent dopants and phase segregation in organolead mixed-halide perovskites

DOE PAGES

Rosales, Bryan A.; Men, Long; Cady, Sarah D.; ...

2016-07-25

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Persistent dopants and phase segregation in organolead mixed-halide perovskites

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

Rosales, Bryan A.; Men, Long; Cady, Sarah D.

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Binary Phase Behavior of Saturated-Unsaturated Mixed-Acid Triacylglycerols-A Review.

PubMed

Zhang, Lu; Ueno, Satoru; Sato, Kiyotaka

2018-06-01

Most natural lipids contain a complex mixture of individual triacylglycerols (TAGs). An in-depth knowledge of the mixing behavior of TAGs is necessary for the rational design and engineering of food materials. The binary phase diagram of TAGs is a simplified model that can be explored to help foster an understanding of the phase behavior of complex fats and oils. This article reviews recent research on the binary phase behavior of saturated-unsaturated mixed-acid TAGs, with special emphasis on the stearicunsaturated and palmitic-unsaturated diacid TAGs. The occurrence of polymorphic forms and mutual solubility of TAG mixtures are strongly related to the glycerol conformation of the saturated-oleic diacid TAGs; it appears to be most influenced by the chain-length mismatch in saturated-elaidic diacid TAGs. In addition, the polymorphism of pure enantiomers and racemic mixture of chiral TAGs was also reviewed, while the effect of chirality on mixing behavior was discussed.

First Principles Calculations of Transition Metal Binary Alloys: Phase Stability and Surface Effects

NASA Astrophysics Data System (ADS)

Aspera, Susan Meñez; Arevalo, Ryan Lacdao; Shimizu, Koji; Kishida, Ryo; Kojima, Kazuki; Linh, Nguyen Hoang; Nakanishi, Hiroshi; Kasai, Hideaki

2017-06-01

The phase stability and surface effects on binary transition metal nano-alloy systems were investigated using density functional theory-based first principles calculations. In this study, we evaluated the cohesive and alloying energies of six binary metal alloy bulk systems that sample each type of alloys according to miscibility, i.e., Au-Ag and Pd-Ag for the solid solution-type alloys (SS), Pd-Ir and Pd-Rh for the high-temperature solid solution-type alloys (HTSS), and Au-Ir and Ag-Rh for the phase-separation (PS)-type alloys. Our results and analysis show consistency with experimental observations on the type of materials in the bulk phase. Varying the lattice parameter was also shown to have an effect on the stability of the bulk mixed alloy system. It was observed, particularly for the PS- and HTSS-type materials, that mixing gains energy from the increasing lattice constant. We furthermore evaluated the surface effects, which is an important factor to consider for nanoparticle-sized alloys, through analysis of the (001) and (111) surface facets. We found that the stability of the surface depends on the optimization of atomic positions and segregation of atoms near/at the surface, particularly for the HTSS and the PS types of metal alloys. Furthermore, the increase in energy for mixing atoms at the interface of the atomic boundaries of PS- and HTSS-type materials is low enough to overcome by the gain in energy through entropy. These, therefore, are the main proponents for the possibility of mixing alloys near the surface.

Hot recycling of asphaltic concrete pavement : IR-15-3(8)121, Wildcat to Pine Creek

DOT National Transportation Integrated Search

1981-02-01

There are various methods of pavement material recycling. This report is devoted to hot-mix plant recycling considerations and procedures. The several phases of the hot-mix recycling process are discussed separately, including removal and size reduct...

Electrically conducting ternary amorphous fully oxidized materials and their application

NASA Technical Reports Server (NTRS)

Giauque, Pierre (Inventor); Nicolet, Marc (Inventor); Gasser, Stefan M. (Inventor); Kolawa, Elzbieta A. (Inventor); Cherry, Hillary (Inventor)

2004-01-01

Electrically active devices are formed using a special conducting material of the form Tm--Ox mixed with SiO2 where the materials are immiscible. The immiscible materials are forced together by using high energy process to form an amorphous phase of the two materials. The amorphous combination of the two materials is electrically conducting but forms an effective barrier.

Molten salt synthesis of La0.8Sr0.2MnO3 powders for SOFC cathode electrode

NASA Astrophysics Data System (ADS)

Gu, Sin-il; Shin, Hyo-soon; Hong, Youn-woo; Yeo, Dong-hun; Kim, Jong-hee; Nahm, Sahn; Yoon, Sang-ok

2012-08-01

For La0.8Sr0.2MnO3 (LSM) perovskite, used as the cathode material for solid oxide fuel cells (SOFC), it is known that the formation of a triple-phase-boundary is restrained due to the formation of a second phase at the YSZ/electrode interface at high temperature. To decrease the 2nd phase, lowering the sintering temperature has been used. LSM powder was synthesized by molten salt synthesis method to control its particle size, shape, and agglomeration. We have characterized the phase formation, particle size, shape, and sintering behavior of LSM in the synthesis using the variation of KCl, LiCl, KF and its mixed salts as raw materials. In the case of KCl and KCl-KF salts, the particle size and shape of the LSM was well controlled and synthesized. However, in the case of LiCl and KCl-LiCl salts, LiMnOx as 2nd phase and LSM were synthesized simultaneously. In the case of the mixed salt of KCl-KF, the growth mechanism of the LSM particle was changed from `diffusion-controlled' to `reaction-controlled' according to the amount of mixed salt. The sintering temperature can be decreased below 1000 °C by using the synthesized LSM powder.

Few layer graphene wrapped mixed phase TiO2 nanofiber as a potential electrode material for high performance supercapacitor applications

NASA Astrophysics Data System (ADS)

Thirugnanam, Lavanya; Sundara, Ramaprabhu

2018-06-01

A combination of favorable composition and optimized anatase/rutile mixed-phase TiO2 (MPTNF)/Hydrogen exfoliated graphene (HEG) composite nanofibers (MPTNF/HEG) and anatase/rutile mixed-phase TiO2/reduced graphene oxide (rGO) composite nanofibers (MPTNF/rGO) have been reported to enhance the electrochemical properties for supercapacitor applications. These composite nanofibers have been synthesized by an efficient route of electrospinning together with the help of easy chemical methods. Both the composites exhibit good charge storage capability with enhanced pseudocapacitance and electric double-layer capacitance (EDLC) as confirmed by cyclic voltammetry studies. MPTNF/HEG composite showed maximum specific capacitance of 210.5 F/g at the current density of 1 A/g, which was mainly due to its availability of the more active sites for ions adsorption on a few layers of graphene wrapped TiO2 nanofiber surface. The synergistic effect of anatase/rutile mixed phase with one dimensional nanostructure and the electronic interaction between TiO2 and few layer graphene provided the subsequent improvement of ion adsorption capacity. Also exhibit excellent electrochemical performance to improve the capacitive properties of TiO2 electrode materials which is required for the development of flexible electrodes in energy storage devices and open up new opportunities for high performance supercapacitors.

Hydrogen trapping under the effect of W-C mixed layers

NASA Astrophysics Data System (ADS)

Liu, N.; Huang, J.; Sato, K.; Xu, Q.; Shi, L. Q.; Wang, Y. X.

2014-03-01

The retention of hydrogen (H) isotope in plasma-facing materials (PFMs) is an important issue for next step fusion device. We used density functional theory (DFT) to study the chemical bonds of H in tungsten-carbon (W-C) mixed layers of tungsten surface, aiming to explore the retention behaviour of H in PFMs. The solubility of C in W was first calculated for revealing the phase components in W-C mixed layers. It was found that C has low solubility in W, which prefers to be segregated on the W surface. Vacancies can enhance the solution of C in W. This makes C appear somewhat carbide feature. Thus, W-C mixed layers should contain multiple phase components. H retention strongly depends on the phase components in the W-C mixed layers. The solution of C will suppress the retention of H in W no matter whether neighbouring vacancies are present, or not. Hydrocarbon precursors, which were observed in desorption experiments, prefer to form by means of H binding to C atoms in C amorphous, or in precipitators in the W-C mixed layers, while not in tungsten carbide phase or in W bulk. Our investigation reasonably explains the experimental results.

Giant nonlinear response at a plasmonic nanofocus drives efficient four-wave mixing

NASA Astrophysics Data System (ADS)

Nielsen, Michael P.; Shi, Xingyuan; Dichtl, Paul; Maier, Stefan A.; Oulton, Rupert F.

2017-12-01

Efficient optical frequency mixing typically must accumulate over large interaction lengths because nonlinear responses in natural materials are inherently weak. This limits the efficiency of mixing processes owing to the requirement of phase matching. Here, we report efficient four-wave mixing (FWM) over micrometer-scale interaction lengths at telecommunications wavelengths on silicon. We used an integrated plasmonic gap waveguide that strongly confines light within a nonlinear organic polymer. The gap waveguide intensifies light by nanofocusing it to a mode cross-section of a few tens of nanometers, thus generating a nonlinear response so strong that efficient FWM accumulates over wavelength-scale distances. This technique opens up nonlinear optics to a regime of relaxed phase matching, with the possibility of compact, broadband, and efficient frequency mixing integrated with silicon photonics.

Structural and thermodynamic aspects of organic-inorganic mixed halide (CH3NH3PbI3-xBrx) perovskite

NASA Astrophysics Data System (ADS)

Singh, Rajan Kumar; Kumar, Ranveer; Jain, Neha; Singh, Jai; Mishra, S. K.

2018-05-01

Mixed Bromine and iodine lead halide perovskite CH3NH3PbI3-xBrx have been synthesized by solution phase method using CH3NH3I and PbBr2 precursors in ambient conditions. X-ray diffraction indicates the formation of cubic perovskite at room temperature with space group of Pm3m. The mixed perovskite improved crystallanity and grain contour which may significant improve photovoltaic performance of perovskite devices. Thermodynamic behavior of such type of material also indicates energy absorption nature of materials.

Microwave phase conjugation using artificial nonlinear microwave surfaces

NASA Astrophysics Data System (ADS)

Chang, Yian

1997-09-01

A new technique is developed and demonstrated to simulate nonlinear materials in the microwave and millimeter wave regime. Such materials are required to extend nonlinear optical techniques into longer wavelength areas. Using an array of antenna coupled mixers as an artificial nonlinear surface, we have demonstrated two-dimensional free space microwave phase conjugation at 10 GHz. The basic concept is to replace the weak nonlinearity of electron distribution in a crystal with the strong nonlinear V-I response of a P-N junction. This demnstration uses a three-wave mixing method with the effective nonlinear susceptibility χ(2) provided by an artificial nonlinear surface. The pump signal at 2ω (20 GHz) can be injected to the mixing elements electrically or optically. Electrical injection was first used to prove the concept of artificial nonlinear surfaces. However, due to the loss and size of microwave components, electrical injection is not practical for an array of artificial nonlinear surfaces, as would be needed in a three-dimensional free space phase conjugation setup. Therefore optical injection was implemented to carry the 2ω microwave pump signal in phase to all mixing elements. In both cases, two-dimensional free space phase conjugation was observed by directly measuring the electric field amplitude and phase distribution. The electric field wavefronts exhibited retro-directivity and auto- correction characteristics of phase conjugation. This demonstration surface also shows a power gain of 10 dB, which is desired for potential communication applications.

Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China

PubMed Central

Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

2016-01-01

In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase. PMID:27011196

Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

PubMed

Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

2016-03-22

In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase.

Monodisperse granular flows in viscous dispersions in a centrifugal acceleration field

NASA Astrophysics Data System (ADS)

Cabrera, Miguel Angel; Wu, Wei

2016-04-01

Granular flows are encountered in geophysical flows and innumerable industrial applications with particulate materials. When mixed with a fluid, a complex network of interactions between the particle- and fluid-phase develops, resulting in a compound material with a yet unclear physical behaviour. In the study of granular suspensions mixed with a viscous dispersion, the scaling of the stress-strain characteristics of the fluid phase needs to account for the level of inertia developed in experiments. However, the required model dimensions and amount of material becomes a main limitation for their study. In recent years, centrifuge modelling has been presented as an alternative for the study of particle-fluid flows in a reduced scaled model in an augmented acceleration field. By formulating simple scaling principles proportional to the equivalent acceleration Ng in the model, the resultant flows share many similarities with field events. In this work we study the scaling principles of the fluid phase and its effects on the flow of granular suspensions. We focus on the dense flow of a monodisperse granular suspension mixed with a viscous fluid phase, flowing down an inclined plane and being driven by a centrifugal acceleration field. The scaled model allows the continuous monitoring of the flow heights, velocity fields, basal pressure and mass flow rates at different Ng levels. The experiments successfully identify the effects of scaling the plastic viscosity of the fluid phase, its relation with the deposition of particles over the inclined plane, and allows formulating a discussion on the suitability of simulating particle-fluid flows in a centrifugal acceleration field.

A testing program to evaluate the effects of simulant mixed wastes on plastic transportation packaging components

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

Nigrey, P.J.; Dickens, T.G.; Dickman, P.T.

1997-08-01

Based on regulatory requirements for Type A and B radioactive material packaging, a Testing Program was developed to evaluate the effects of mixed wastes on plastic materials which could be used as liners and seals in transportation containers. The plastics evaluated in this program were butadiene-acrylonitrile copolymer (Nitrile rubber), cross-linked polyethylene, epichlorohydrin, ethylene-propylene rubber (EPDM), fluorocarbons, high-density polyethylene (HDPE), butyl rubber, polypropylene, polytetrafluoroethylene, and styrene-butadiene rubber (SBR). These plastics were first screened in four simulant mixed wastes. The liner materials were screened using specific gravity measurements and seal materials by vapor transport rate (VTR) measurements. For the screening of linermore » materials, Kel-F, HDPE, and XLPE were found to offer the greatest resistance to the combination of radiation and chemicals. The tests also indicated that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the chlorinated hydrocarbon simulant mixed waste, only Viton passed the screening tests. In both the simulant scintillation fluid mixed waste and the ketone mixture waste, none of the seal materials met the screening criteria. Those materials which passed the screening tests were subjected to further comprehensive testing in each of the simulant wastes. The materials were exposed to four different radiation doses followed by exposure to a simulant mixed waste at three temperatures and four different exposure times (7, 14, 28, 180 days). Materials were tested by measuring specific gravity, dimensional, hardness, stress cracking, VTR, compression set, and tensile properties. The second phase of this Testing Program involving the comprehensive testing of plastic liner has been completed and for seal materials is currently in progress.« less

The Investigation of Magnesium Perchlorate/Iron Phase-mineral Mixtures as a Possible Source of Oxygen and Chlorine Detected by the Sample Analysis at Mars (SAM) Instrument in Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Sutter, B.; Heil, E.; Archer, P. D.; Ming, D. W.; Eigenbrode, J. L.; Franz, H. B.; Glavin, D. P.; McAdam, A. C.; Mahaffy, P. R.; Niles, P. B.;

Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

DOE PAGES

Zhou, Lan; Suram, Santosh K.; Becerra-Stasiewicz, Natalie; ...

2015-05-27

Recent efforts have demonstrated enhanced tailoring of material functionality with mixed-anion materials, yet exploratory research with mixed-anion chemistries is limited by the sensitivity of these materials to synthesis conditions. In order to synthesize a particular metal oxynitride compound by traditional reactive annealing we require specific, limited ranges of both oxygen and nitrogen chemical potentials in order to establish equilibrium between the solid-state material and a reactive atmosphere. While using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing for synthesis of mixed-anion inorganic materials. Heuristic optimization of reactive gas pressures to attainmore » a desired anion stoichiometry is discussed, and the ability of rapid thermal processing to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide and oxynitride phases.« less

Methods for forming particles

DOEpatents

Fox, Robert V.; Zhang, Fengyan; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin

2016-06-21

Single source precursors or pre-copolymers of single source precursors are subjected to microwave radiation to form particles of a I-III-VI.sub.2 material. Such particles may be formed in a wurtzite phase and may be converted to a chalcopyrite phase by, for example, exposure to heat. The particles in the wurtzite phase may have a substantially hexagonal shape that enables stacking into ordered layers. The particles in the wurtzite phase may be mixed with particles in the chalcopyrite phase (i.e., chalcopyrite nanoparticles) that may fill voids within the ordered layers of the particles in the wurtzite phase thus produce films with good coverage. In some embodiments, the methods are used to form layers of semiconductor materials comprising a I-III-VI.sub.2 material. Devices such as, for example, thin-film solar cells may be fabricated using such methods.

Phases and structures of sunset yellow and disodium cromoglycate mixtures in water.

PubMed

Yamaguchi, Akihiro; Smith, Gregory P; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Zhu, Chenhui; Clark, Noel A

2016-01-01

We study phases and structures of mixtures of two representative chromonic liquid crystal materials, sunset yellow FCF (SSY) and disodium cromoglycate (DSCG), in water. A variety of combinations of isotropic, nematic (N), and columnar (also called M) phases are observed depending on their concentrations, and a phase diagram is made. We find a tendency for DSCG-rich regions to show higher-order phases while SSY-rich regions show lower-order ones. We observe uniform mesophases only when one of the materials is sparse in the N phases. Their miscibility in M phases is so low that essentially complete phase separation occurs. X-ray scattering and spectroscopy studies confirm that SSY and DSCG molecules do not mix when they form chromonic aggregates and neither do their aggregates when they form M phases.

Transient analysis of a thermal storage unit involving a phase change material

NASA Technical Reports Server (NTRS)

Griggs, E. I.; Pitts, D. R.; Humphries, W. R.

1974-01-01

The transient response of a single cell of a typical phase change material type thermal capacitor has been modeled using numerical conductive heat transfer techniques. The cell consists of a base plate, an insulated top, and two vertical walls (fins) forming a two-dimensional cavity filled with a phase change material. Both explicit and implicit numerical formulations are outlined. A mixed explicit-implicit scheme which treats the fin implicity while treating the phase change material explicitly is discussed. A band algorithmic scheme is used to reduce computer storage requirements for the implicit approach while retaining a relatively fine grid. All formulations are presented in dimensionless form thereby enabling application to geometrically similar problems. Typical parametric results are graphically presented for the case of melting with constant heat input to the base of the cell.

Synthetic oligonucleotide separations by mixed-mode reversed-phase/weak anion-exchange liquid chromatography.

PubMed

Zimmermann, Aleksandra; Greco, Roberto; Walker, Isabel; Horak, Jeannie; Cavazzini, Alberto; Lämmerhofer, Michael

2014-08-08

Synthetic oligonucleotides gain increasing importance in new therapeutic concepts and as probes in biological sciences. If pharmaceutical-grade purities are required, chromatographic purification using ion-pair reversed-phase chromatography is commonly carried out. However, separation selectivity for structurally closely related impurities is often insufficient, especially at high sample loads. In this study, a "mixed-mode" reversed-phase/weak anion exchanger stationary phase has been investigated as an alternative tool for chromatographic separation of synthetic oligonucleotides with minor sequence variations. The employed mixed-mode phase shows great flexibility in method development. It has been run in various gradient elution modes, viz. one, two or three parameter (mixed) gradients (altering buffer pH, buffer concentration, and organic modifier) to find optimal elution conditions and gain further insight into retention mechanisms. Compared to ion-pair reversed-phase and mere anion-exchange separation, enhanced selectivities were observed with the mixed-mode phase for 20-23 nucleotide (nt) long oligonucleotides with similar sequences. Oligonucleotides differing by 1, 2 or 3 nucleotides in length could be readily resolved and separation factors for single nucleotide replacements declined in the order Cytosine (C)/Guanine (G)>Adenine (A)/Guanine∼Guanine/Thymine (T)>Adenine/Cytosine∼Cytosine/Thymine>Adenine/Thymine. Selectivities were larger when the modification was at the 3' terminal-end, declined when it was in the middle of the sequence and was smallest when it was located at the 5' terminus. Due to the lower surface area of the 200Å pore size mixed-mode stationary phase compared to the corresponding 100Å material, lower retention times with equal selectivities under milder elution conditions were achievable. Considering high sample loading capacities of the mixed-mode anion-exchanger phase, it should have great potential for chromatographic oligonucleotide separation and purification. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

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

Hägglund, Carl, E-mail: carl.hagglund@angstrom.uu.se; Grehl, Thomas; Brongersma, Hidde H.

2016-03-15

A broad and expanding range of materials can be produced by atomic layer deposition at relatively low temperatures, including both oxides and metals. For many applications of interest, however, it is desirable to grow more tailored and complex materials such as semiconductors with a certain doping, mixed oxides, and metallic alloys. How well such mixed materials can be accomplished with atomic layer deposition requires knowledge of the conditions under which the resulting films will be mixed, solid solutions, or laminated. The growth and lamination of zinc oxide and tin oxide is studied here by means of the extremely surface sensitivemore » technique of low energy ion scattering, combined with bulk composition and thickness determination, and x-ray diffraction. At the low temperatures used for deposition (150 °C), there is little evidence for atomic scale mixing even with the smallest possible bilayer period, and instead a morphology with small ZnO inclusions in a SnO{sub x} matrix is deduced. Postannealing of such laminates above 400 °C however produces a stable surface phase with a 30% increased density. From the surface stoichiometry, this is likely the inverted spinel of zinc stannate, Zn{sub 2}SnO{sub 4}. Annealing to 800 °C results in films containing crystalline Zn{sub 2}SnO{sub 4}, or multilayered films of crystalline ZnO, Zn{sub 2}SnO{sub 4}, and SnO{sub 2} phases, depending on the bilayer period.« less

Conching Chocolate

NASA Astrophysics Data System (ADS)

Hunter, Gary L.; Chaikin, Paul; Blanco, Elena; Poon, Wilson

2014-03-01

``Conching'' is an intermediate step in the processing of chocolate where hydrophilic solid particles, such as sugar and milk proteins, are aggressively mixed into a fatty, fluid phase containing emulsifier, e.g. molten cocoa butter with lecithin. During conching, the system evolves from a fine powder to a coarser granulated material and ultimately into a thick cohesive paste. Our goal is to better understand the evolution of chocolate during conching and the transition from an effectively dry to a wet or immersed granular material. In particular, we focus on how mixing times change in response to variations in solid particle volume fractions and emulsifier concentration. As a function of volume fraction, mixing times are well-described by a conventional form that diverges at a finite volume fraction. Furthermore, mixing times can be collapsed onto a universal curve as a function of mixing speed and emulsifier concentration.

Novel phase diagram behavior and materials design in heterostructural semiconductor alloys

PubMed Central

Holder, Aaron M.; Siol, Sebastian; Ndione, Paul F.; Peng, Haowei; Deml, Ann M.; Matthews, Bethany E.; Schelhas, Laura T.; Toney, Michael F.; Gordon, Roy G.; Tumas, William; Perkins, John D.; Ginley, David S.; Gorman, Brian P.; Tate, Janet; Zakutayev, Andriy; Lany, Stephan

2017-01-01

Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the critical composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region. PMID:28630928

Novel phase diagram behavior and materials design in heterostructural semiconductor alloys.

PubMed

Holder, Aaron M; Siol, Sebastian; Ndione, Paul F; Peng, Haowei; Deml, Ann M; Matthews, Bethany E; Schelhas, Laura T; Toney, Michael F; Gordon, Roy G; Tumas, William; Perkins, John D; Ginley, David S; Gorman, Brian P; Tate, Janet; Zakutayev, Andriy; Lany, Stephan

2017-06-01

Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the critical composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region.

Novel phase diagram behavior and materials design in heterostructural semiconductor alloys

DOE PAGES

Holder, Aaron M.; Siol, Sebastian; Ndione, Paul F.; ...

2017-06-07

Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the criticalmore » composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Furthermore, thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region.« less

Declining availability of outdoor skating in Canada

NASA Astrophysics Data System (ADS)

Brammer, Jeremy R.; Samson, Jason; Humphries, Murray M.

2015-01-01

We find a mixed chirality $d$-wave superconducting state in the coexistence region between antiferromagnetism and interaction-driven superconductivity in lightly doped honeycomb materials. This state has a topological chiral $d+id$-wave symmetry in one Dirac valley but $d-id$-wave symmetry in the other valley and hosts two counter-propagating edge states, protected in the absence of intervalley scattering. A first-order topological phase transition, with no bulk gap closing, separates the chiral $d$-wave state at small magnetic moments from the mixed chirality $d$-wave phase.

Origin of Reversible Photoinduced Phase Separation in Hybrid Perovskites.

PubMed

Bischak, Connor G; Hetherington, Craig L; Wu, Hao; Aloni, Shaul; Ogletree, D Frank; Limmer, David T; Ginsberg, Naomi S

2017-02-08

The distinct physical properties of hybrid organic-inorganic materials can lead to unexpected nonequilibrium phenomena that are difficult to characterize due to the broad range of length and time scales involved. For instance, mixed halide hybrid perovskites are promising materials for optoelectronics, yet bulk measurements suggest the halides reversibly phase separate upon photoexcitation. By combining nanoscale imaging and multiscale modeling, we find that the nature of halide demixing in these materials is distinct from macroscopic phase separation. We propose that the localized strain induced by a single photoexcited charge interacting with the soft, ionic lattice is sufficient to promote halide phase separation and nucleate a light-stabilized, low-bandgap, ∼8 nm iodide-rich cluster. The limited extent of this polaron is essential to promote demixing because by contrast bulk strain would simply be relaxed. Photoinduced phase separation is therefore a consequence of the unique electromechanical properties of this hybrid class of materials. Exploiting photoinduced phase separation and other nonequilibrium phenomena in hybrid materials more generally could expand applications in sensing, switching, memory, and energy storage.

Solution based synthesis of mixed-phase materials in the Li2TiO3-Li4SiO4 system

NASA Astrophysics Data System (ADS)

Hanaor, Dorian A. H.; Kolb, Matthias H. H.; Gan, Yixiang; Kamlah, Marc; Knitter, Regina

2015-01-01

As candidate tritium breeder materials for use in the ITER helium cooled pebble bed, ceramic multiphasic compounds lying in the region of the quasi-binary lithium metatitanate-lithium orthosilicate system may exhibit mechanical and physical advantages relative to single phase materials. Here we present an organometallic solution-based synthesis procedure for the low-temperature fabrication of compounds in the Li2TiO3-Li4SiO4 region and investigate phase stability and transformations through temperature varied X-ray diffraction and scanning calorimetry. Results demonstrate that the metatitanate and metasilicate phases Li2TiO3 and Li2SiO3 readily crystallise in nanocrystalline form at temperatures below 180 °C. Lithium deficiency in the region of 5% results from Li sublimation from Li4SiO4 and/or from excess Li incorporation in the metatitanate phase and brings about a stoichiometry shift, with product compounds exhibiting mixed lithium orthosilicate/metasilicate content towards the Si rich region and predominantly Li2TiO3 content towards the Ti rich region. Above 1150 °C the transformation of monoclinic to cubic γ-Li2TiO3 disordered solid-solution occurs while the melting of silicate phases indicates a likely monotectic type system with a solidus line in the region 1050-1100 °C. Synthesis procedures involving a lithium chloride precursor are not likely to be a viable option for breeder pebble synthesis as this route was found to yield materials with a more significant Li-deficiency exhibiting the crystallisation of the Li2TiSiO5 phase at intermediate compositions.

Multiphase materials with lignin. IV. Blends of hydroxypropyl cellulose with lignin

Treesearch

Timothy G. Rials; Wolfgang G. Glasser

1989-01-01

Polymer blends of hydroxypropyl cellulose (HPC) and organosolv lignin (OSL) were prepared by mixing in solutions of both pyridine and dioxane, and casting as films, and by mixing in the melt followed by extrusion. All preparations exhibited partial miscibility as evidenced by a single Tg up to a composition of 40 wt % lignin above which phase...

Chemical compatibility screening test results

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

Nigrey, P.J.; Dickens, T.G.

1997-12-01

A program for evaluating packaging components that may be used in transporting mixed-waste forms has been developed and the first phase has been completed. This effort involved the screening of ten plastic materials in four simulant mixed-waste types. These plastics were butadiene-acrylonitrile copolymer rubber, cross-linked polyethylene (XLPE), epichlorohydrin rubber, ethylene-propylene rubber (EPDM), fluorocarbon (Viton or Kel-F), polytetrafluoroethylene, high-density polyethylene (HDPE), isobutylene-isoprene copolymer rubber (butyl), polypropylene, and styrene-butadiene rubber (SBR). The selected simulant mixed wastes were (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) amore » mixture of ketones. The testing protocol involved exposing the respective materials to 286,000 rads of gamma radiation followed by 14-day exposures to the waste types at 60{degrees}C. The seal materials were tested using vapor transport rate (VTR) measurements while the liner materials were tested using specific gravity as a metric. For these tests, a screening criterion of 0.9 g/hr/m{sup 2} for VTR and a specific gravity change of 10% was used. Based on this work, it was concluded that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the chlorinated hydrocarbon simulant mixed waste, only Viton passed the screening tests. In both the simulant scintillation fluid mixed waste and the ketone mixture simulant mixed waste, none of the seal materials met the screening criteria. For specific gravity testing of liner materials, the data showed that while all materials with the exception of polypropylene passed the screening criteria, Kel-F, HDPE, and XLPE offered the greatest resistance to the combination of radiation and chemicals.« less

In situ observation of stishovite formation in shock-compressed fused silica

NASA Astrophysics Data System (ADS)

Tracy, Sally June; Turneaure, Stefan; Duffy, Thomas

2017-06-01

Silica, SiO2, has widespread applications ranging from optical components to refractory materials and is of geological importance as one of the major oxide components of the Earth's crust and mantle. The response of silica phases to dynamic loading has long been of interest for understanding the structural evolution of this fundamental oxide. Under shock compression both crystalline quartz and fused silica are characterized by the occurrence of a broad `mixed-phase region' (15-40 GPa) and a dense, high-pressure phase with much lower compressibility. Despite decades of study, the nature of this transformation and the identity of the high-pressure phase(s) remain poorly understood. In situ x-ray diffraction experiments on shock-compressed fused silica were conducted at the Dynamic Compression Sector of the Advanced Photon Source. The lattice-level structure was investigated through time-resolved x-ray diffraction measurements on samples reaching peak stress ranging from 12 to 47 GPa. Our results demonstrate that SiO2 adopts a dense amorphous structure in the `mixed-phase region' and abruptly transforms to stishovite above 34 GPa. These results provide clear evidence that high-pressure crystalline silicate phases can form from amorphous starting materials on the time-scale of laboratory shock experiments.

Development of high Tc (greater than 100 K) Bi, Tl and Y-based materials as superconducting circuit elements

NASA Technical Reports Server (NTRS)

Haertling, Gene; Grabert, Gregory; Gilmour, Phillip

1994-01-01

Experimental work on this project over the last four years has resulted in establishing processing and characterization techniques for producing both the Bi-based and Tl-based superconductors in their high temperature (2223) forms. In the bulk, dry pressed form, maximum critical temperatures (Tc) of 108.2 K and 117.8 K, respectively, were measured. Results have further shown that the Bi and Tl-based superconducting materials in bulk form are noticeably different from the Y-based 123 material in that superconductivity is considerably harder to achieve, maintain, and reproduce. This is due primarily to the difficulty in obtaining the higher Tc phase in pure form since it commonly co-exists with other undesirable, lower Tc phases. In particular, it has been found that long processing times for calcining and firing (20 - 200 hrs.) and close control of temperatures which are very near the melting point are required in order to obtain higher proportions of the desirable, high Tc (2223) phase. Thus far, the BSCCO bulk materials has been prepared in uniaxially pressed, hot pressed, and tapecast form. The uniaxially pressed material has been synthesized by the mixed oxide, coprecipitation, and melt quenching processes. The tapecast and hot pressed materials have been prepared via the mixed oxide process. In addition, thick films of BSCCO (2223 phase) have been prepared by screen printing on to yttria and magnesia stabilized zirconia with only moderate success; i.e., superconductivity was achieved in these thick films, but the highest Tc obtained in these films was 89.0 K. The Tc's of the bulk hot pressed, tapecast, and screen printed thick film materials were found to be 108.2, 102.4, and 89.0 K, respectively.

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.

Template assisted strain tuning and phase stabilization in epitaxial BiFeO3 thin films

NASA Astrophysics Data System (ADS)

Saj Mohan M., M.; Ramadurai, Ranjith

2018-04-01

Strain engineering is a key to develop novel properties in functional materials. We report a strain mediated phase stabilization and epitaxial growth of bismuth ferrite(BiFeO3) thin films on LaAlO3 (LAO) substrates. The strain in the epitaxial layer is controlled by controlling the thickness of bottom electrode where the thickness of the BFO is kept constant. The thickness of La0.7Sr0.3MnO3(LSMO) template layer was optimized to grow completely strained tetragonal, tetragonal/rhombohedral mixed phase and fully relaxed rhombohedral phase of BFO layers. The results were confirmed with coupled-θ-2θ scan, and small area reciprocal space mapping. The piezoelectric d33 (˜ 45-48 pm/V) coefficient of the mixed phase was relatively larger than the strained tetragonal and relaxed rhombohedral phase for a given thickness.

Mixed-Mode Operation of Hybrid Phase-Change Nanophotonic Circuits.

PubMed

Lu, Yegang; Stegmaier, Matthias; Nukala, Pavan; Giambra, Marco A; Ferrari, Simone; Busacca, Alessandro; Pernice, Wolfram H P; Agarwal, Ritesh

2017-01-11

Phase change materials (PCMs) are highly attractive for nonvolatile electrical and all-optical memory applications because of unique features such as ultrafast and reversible phase transitions, long-term endurance, and high scalability to nanoscale dimensions. Understanding their transient characteristics upon phase transition in both the electrical and the optical domains is essential for using PCMs in future multifunctional optoelectronic circuits. Here, we use a PCM nanowire embedded into a nanophotonic circuit to study switching dynamics in mixed-mode operation. Evanescent coupling between light traveling along waveguides and a phase-change nanowire enables reversible phase transition between amorphous and crystalline states. We perform time-resolved measurements of the transient change in both the optical transmission and resistance of the nanowire and show reversible switching operations in both the optical and the electrical domains. Our results pave the way toward on-chip multifunctional optoelectronic integrated devices, waveguide integrated memories, and hybrid processing applications.

Ultrafast Dynamics in Vanadium Dioxide: Separating Spatially Segregated Mixed Phase Dynamics in the Time-domain

NASA Astrophysics Data System (ADS)

Hilton, David

2011-10-01

In correlated electronic systems, observed electronic and structural behavior results from the complex interplay between multiple, sometimes competing degrees-of- freedom. One such material used to study insulator-to-metal transitions is vanadium dioxide, which undergoes a phase transition from a monoclinic-insulating phase to a rutile-metallic phase when the sample is heated to 340 K. The major open question with this material is the relative influence of this structural phase transition (Peirels transition) and the effects of electronic correlations (Mott transition) on the observed insulator-to-metal transition. Answers to these major questions are complicated by vanadium dioxide's sensitivity to perturbations in the chemical structure in VO2. For example, related VxOy oxides with nearly a 2:1 ratio do not demonstrate the insulator-to- metal transition, while recent work has demonstrated that W:VO2 has demonstrated a tunable transition temperature controllable with tungsten doping. All of these preexisting results suggest that the observed electronic properties are exquisitely sensitive to the sample disorder. Using ultrafast spectroscopic techniques, it is now possible to impulsively excite this transition and investigate the photoinduced counterpart to this thermal phase transition in a strongly nonequilibrium regime. I will discuss our recent results studying the terahertz-frequency conductivity dynamics of this photoinduced phase transition in the poorly understood near threshold temperature range. We find a dramatic softening of the transition near the critical temperature, which results primarily from the mixed phase coexistence near the transition temperature. To directly study this mixed phase behavior, we directly study the nucleation and growth rates of the metallic phase in the parent insulator using non-degenerate optical pump-probe spectroscopy. These experiments measure, in the time- domain, the coexistent phase separation in VO2 (spatially separated insulator and metal islands) and, more importantly, their dynamic evolution in response to optical excitation.

Mixed micelle cloud point-magnetic dispersive μ-solid phase extraction of doxazosin and alfuzosin

NASA Astrophysics Data System (ADS)

Gao, Nannan; Wu, Hao; Chang, Yafen; Guo, Xiaozhen; Zhang, Lizhen; Du, Liming; Fu, Yunlong

2015-01-01

Mixed micelle cloud point extraction (MM-CPE) combined with magnetic dispersive μ-solid phase extraction (MD-μ-SPE) has been developed as a new approach for the extraction of doxazosin (DOX) and alfuzosin (ALF) prior to fluorescence analysis. The mixed micelle anionic surfactant sodium dodecyl sulfate and non-ionic polyoxyethylene(7.5)nonylphenylether was used as the extraction solvent in MM-CPE, and diatomite bonding Fe3O4 magnetic nanoparticles were used as the adsorbent in MD-μ-SPE. The method was based on MM-CPE of DOX and ALF in the surfactant-rich phase. Magnetic materials were used to retrieve the surfactant-rich phase, which easily separated from the aqueous phase under magnetic field. At optimum conditions, a linear relationship between DOX and ALF was obtained in the range of 5-300 ng mL-1, and the limits of detection were 0.21 and 0.16 ng mL-1, respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine samples, and plasma samples.

Spallation as a dominant source of pusher-fuel and hot-spot mix in inertial confinement fusion capsules

DOE PAGES

Orth, Charles D.

2016-02-23

We suggest that a potentially dominant but previously neglected source of pusher-fuel and hot-spot “mix” may have been the main degradation mechanism for fusion energy yields of modern inertial confinement fusion (ICF) capsules designed and fielded to achieve high yields — not hydrodynamic instabilities. This potentially dominant mix source is the spallation of small chunks or “grains” of pusher material into the fuel regions whenever (1) the solid material adjacent to the fuel changes its phase by nucleation, and (2) this solid material spalls under shock loading and sudden decompression. Finally, we describe this mix mechanism, support it with simulationsmore » and experimental evidence, and explain how to eliminate it and thereby allow higher yields for ICF capsules and possibly ignition at the National Ignition Facility.« less

Development of form stable Poly(methyl methacrylate) (PMMA) coated thermal phase change material for solar water heater applications

NASA Astrophysics Data System (ADS)

Munusamy, Y.; Shanmugam, S.; Shi-Ying, Kee

2018-04-01

Phase change material (PCM) is one of the most popular and widely used thermal energy storage material in solar water heater because it able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. However the practical application of PCM is limited by two major issues; 1) leakage which leads to material loss and corrosion of tank and 2) large volume change during phase change process which cause pressure build up in the tank. In this work, form-stable PCM was prepared by coating myristic acid with Poly(methyl methacrylate) (PMMA) to prevent leakage of PCM. PMMA was mixed with different weight percentage (0.1, 0.2, 0.3, 0.4 and 0.5 wt%) of dicumyl peroxide (DCP). The purpose of adding DCP to PMMA is to crosslink the polymer and to increase the mechanical strength of PMMA to hold the myristic acid content inside the coating during the phase change process. Leakage test results showed that PMMA mixed with 0.1% DCP exhibit 0% leakage. This result is further supported by Field Emission Scanning Electron Microscopy (FESEM) images and Fourier transform infrared spectroscopy (FTIR) analysis results, where a compact and uniform coating without cracks were formed for PCM coated with PMMA with 0.1% DCP. Differential scanning calorimetry (DSC) results shows that the melting point of form-stable PCM is 55°C, freezing point is 50°C, the latent heat of melting and freezing is 67.59 J/g.

Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

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

Lin, Manhua; Wang, Xiang; Yeom, Younghoon

A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase id dispersed.

Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

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

Lin, Manhua; Wang, Xiang; Yeom, Younghoon

A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase is dispersed.

An X-ray transparent microfluidic platform for screening of the phase behavior of lipidic mesophases

PubMed Central

Khvostichenko, Daria S.; Kondrashkina, Elena; Perry, Sarah L.; Pawate, Ashtamurthy S.; Brister, Keith

2013-01-01

Lipidic mesophases are a class of highly ordered soft materials that form when certain lipids are mixed with water. Understanding the relationship between the composition and the microstructure of mesophases is necessary for fundamental studies of self-assembly in amphiphilic systems and for applications, such as crystallization of membrane proteins. However, the laborious formulation protocol for highly viscous mesophases and the large amounts of material required for sample formulation are significant obstacles in such studies. Here we report a microfluidic platform that facilitates investigations of the phase behavior of mesophases by reducing sample consumption, and automating and parallelizing sample formulation. The mesophases were formulated on-chip using less than 40 nL of material per sample and their microstructure was analyzed in situ using small-angle X-ray scattering (SAXS). The 220 μm-thick X-ray compatible platform was comprised of thin polydimethylsiloxane (PDMS) layers sandwiched between cyclic olefin copolymer (COC) sheets. Uniform mesophases were prepared using an active on-chip mixing strategy coupled with periodic cooling of the sample to reduce the viscosity. We validated the platform by preparing and analyzing mesophases of lipid monoolein (MO) mixed with aqueous solutions of different concentrations of β-octylglucoside (βOG), a detergent frequently used in membrane protein crystallization. Four samples were prepared in parallel on chip, by first metering and automatically diluting βOG to obtain detergent solutions of different concentration, then metering MO, and finally mixing by actuation of pneumatic valves. Integration of detergent dilution and subsequent mixing significantly reduced the number of manual steps needed for sample preparation. Three different types of mesophases typical for monoolein were successfully identified in SAXS data from on-chip samples. Microstructural parameters of identical samples formulated in different chips showed excellent agreement. Phase behavior observed on-chip corresponded well with that of samples prepared via the traditional coupled-syringe method (“off-chip”) using 300-fold larger amount of material, further validating the utility of the microfluidic platform for on-chip characterization of mesophase behavior. PMID:23882463

Demixing of aqueous polymer two-phase systems in low gravity

NASA Technical Reports Server (NTRS)

Bamberger, S.; Harris, J. M.; Baird, J. K.; Boyce, J.; Vanalstine, J. M.; Snyder, R. S.; Brooks, D. E.

1986-01-01

When polymers such as dextran and poly(ethylene glycol) are mixed in aqueous solution biphasic systems often form. On Earth the emulsion formed by mixing the phases rapidly demixes because of phase density differences. Biological materials can be purified by selective partitioning between the phases. In the case of cells and other particulates the efficiency of these separations appears to be somewhat compromised by the demixing process. To modify this process and to evaluate the potential of two-phase partitioning in space, experiments on the effects of gravity on phase emulsion demixing were undertaken. The behavior of phase systems with essentially identical phase densities was studied at one-g and during low-g parabolic aircraft maneuvers. The results indicate the demixing can occur rather rapidly in space, although more slowly than on Earth. The demixing process was examined from a theoretical standpoint by applying the theory of Ostwald ripening. This theory predicts demizing rates many orders of magnitude lower than observed. Other possible demixing mechanisms are considered.

Comprehensive testing to measure the response of butyl rubber to Hanford tank waste simulant

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

NIGREY,PAUL J.

This report presents the findings of the Chemical Compatibility Program developed to evaluate plastic packaging components that may be incorporated in packaging mixed-waste forms for transportation. Consistent with the methodology outlined in this report, the authors performed the second phase of this experimental program to determine the effects of simulant Hanford tank mixed wastes on packaging seal materials. That effort involved the comprehensive testing of five plastic liner materials in an aqueous mixed-waste simulant. The testing protocol involved exposing the materials to {approximately}143, 286, 571, and 3,670 krad of gamma radiation and was followed by 7-, 14-, 28-, 180-day exposuresmore » to the waste simulant at 18, 50, and 60 C. Butyl rubber samples subjected to the same protocol were then evaluated by measuring seven material properties: specific gravity, dimensional changes, mass changes, hardness, compression set, vapor transport rates, and tensile properties. From the analyses, they determined that butyl rubber has relatively good resistance to radiation, this simulant, and a combination of these factors. These results suggest that butyl rubber is a relatively good seal material to withstand aqueous mixed wastes having similar composition to the one used in this study.« less

Response of ethylene propylene diene monomer rubber (EPDM) to simulant Hanford tank waste

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

NIGREY,PAUL J.

2000-02-01

This report presents the findings of the Chemical Compatibility Program developed to evaluate plastic packaging components that may be incorporated in packaging mixed-waste forms for transportation. Consistent with the methodology outlined in this report, the author performed the second phase of this experimental program to determine the effects of simulant Hanford tank mixed wastes on packaging seal materials. That effort involved the comprehensive testing of five plastic liner materials in an aqueous mixed-waste simulant. The testing protocol involved exposing the materials to {approximately}143, 286, 571, and 3,670 krad of gamma radiation and was followed by 7-, 14-, 28-, 180-day exposuresmore » to the waste simulant at 18, 50, and 60 C. Ethylene propylene diene monomer (EPDM) rubber samples subjected to the same protocol were then evaluated by measuring seven material properties: specific gravity, dimensional changes, mass changes, hardness, compression set, vapor transport rates, and tensile properties. The author has determined that EPDM rubber has excellent resistance to radiation, this simulant, and a combination of these factors. These results suggest that EPDM is an excellent seal material to withstand aqueous mixed wastes having similar composition to the one used in this study.« less

Some analyses of the chemistry and diffusion of SST exhaust materials during phase 3 of the wake period. [in lower stratosphere

NASA Technical Reports Server (NTRS)

Hilst, G. R.; Donaldson, C. D.; Contiliano, R. M.

1973-01-01

In the generally stably stratified lower stratosphere, SST exhaust plumes could spend a significant length of time in a relatively undispersed state. This effort has utilized invariant modeling techniques to simulate the separate and combined effects of atmospheric turbulence, turbulent diffusion, and chemical reactions of SST exhaust materials in the lower stratosphere. The primary results to date are: (1) The combination of relatively slow diffusive mixing and rapid chemical reactions during the Phase III wake period minimizes the effect of SST exhausts on O3 depletion by the so-called NOx catalytic cycle. While the SST-produced NO is substantially above background concentrations, it appears diffusive mixing of NO and O3 is simply too slow to produce the O3 depletions originally proposed. (2) The time required to dilute the SST exhaust plume may be a significant fraction of the total time these materials are resident in the lower stratosphere. If this is the case, then prior estimates of the environmental impact of these materials must be revised significantly downward.

Nonlinear Optics Technology. Phase 3. Volume 2. Phase Conjugated Optical Communication Link

DTIC Science & Technology

1991-01-12

experiments and mechanical design of the artificial turbulence generator (turbox), Dr. George M. Harpole who provided the technical design of the turbox, Dr...understanding of FWM PC comm link physics and to determine design requirements for a fieldable system. The system model demonstrated that phase...using photorefractive material was also designed , fabricated, and characterized. The efficiency of heterodyne mixing of an aberrated beacon beam was

Origin of Reversible Photoinduced Phase Separation in Hybrid Perovskites

NASA Astrophysics Data System (ADS)

Bischak, Connor G.; Hetherington, Craig L.; Wu, Hao; Aloni, Shaul; Ogletree, D. Frank; Limmer, David T.; Ginsberg, Naomi S.

2017-02-01

Nonequilibrium processes occurring in functional materials can significantly impact device efficiencies and are often difficult to characterize due to the broad range of length and time scales involved. In particular, mixed halide hybrid perovskites are promising for optoelectronics, yet the halides reversibly phase separate when photo-excited, significantly altering device performance. By combining nanoscale imaging and multiscale modeling, we elucidate the mechanism underlying this phenomenon, demonstrating that local strain induced by photo-generated polarons promotes halide phase separation and leads to nucleation of light-stabilized iodide-rich clusters. This effect relies on the unique electromechanical properties of hybrid materials, characteristic of neither their organic nor inorganic constituents alone. Exploiting photo-induced phase separation and other nonequilibrium phenomena in hybrid materials, generally, could enable new opportunities for expanding the functional applications in sensing, photoswitching, optical memory, and energy storage.

Development of a novel wet oxidation process for hazardous and mixed wastes

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

Dhooge, P.M.

1994-11-01

This article describes and evaluates the DETOX{sup sm} process for processing of mixed wastes. Many DOE waste streams and remediates contain complex and variable mixtures of organic compounds, toxic metals, and radionuclides, often dispersed in organic or inorganic matrices, such as personal protective equipment, various sludges, soils, and water. The DETOX{sup sm} process, patented by Delphi Research, uses a unique combination of metal catalysts to increase the rate of oxidation of organic materials. Included are the following subject areas: project description (phases I-IV); results of all phases; and future work. 5 figs., 1 tab.

Mixed material formation and erosion

NASA Astrophysics Data System (ADS)

Linsmeier, Ch.; Luthin, J.; Goldstraß, P.

2001-03-01

The formation of mixed phases on materials relevant for first wall components of fusion devices is studied under well-defined conditions in ultra-high vacuum (UHV). This is necessary in order to determine fundamental parameters governing the basic processes of chemical reaction, material mixing and erosion. We examined the binary systems comprising of the wall materials beryllium, silicon, tungsten and titanium and carbon, the latter being both a wall material and a plasma impurity. Experiments were carried out to study the interaction of carbon in the form of a vapor-deposited component on clean, well-defined elemental surfaces. The chemical composition and the binding state are measured by X-ray photoelectron spectroscopy (XPS) after annealing treatments. For all materials, a limited carbide formation is found at room temperature. Annealing carbon films on elemental substrate leads to a complete carbidization of the carbon layer. The carbide layers on Be and Si are stable even at very high temperatures, whereas the carbides of Ti and W dissolve. The erosion of these two metals by sputtering is then identical to the pure metals, whereas for Be and Si a protective carbide layer can reduce the sputtering yields.

Experimental constraints and theoretical bases for microstructural damage in plate boundary shear zones

NASA Astrophysics Data System (ADS)

Skemer, P. A.; Cross, A. J.; Bercovici, D.

2016-12-01

(Ultra)mylonites from plate boundary shear zones are characterized by severe grain-size reduction and well-mixed mineral phases. The evolution from relatively undeformed tectonite protoliths to highly deformed (ultra)mylonites via the formation of new grain and phase boundaries is described as microstructural `damage.' Microstructural damage is important for two reasons: grain-size reduction is thought to result in significant rheological weakening, while phase mixing inhibits mechanical recovery and preserves the zone of weakness to be reactivated repeatedly throughout the tectonic cycle. Grain-size reduction by dynamic recrystallization has been studied extensively in both geologic and engineered materials, yet the progressive mixing of mineral phases during high pressure/temperature shear - the other essential element of damage or mylonitization - is not well understood. In this contribution we present new experimental results and theory related to two distinct phase mixing processes. First, we describe high strain torsion experiments on calcite and anhydrite mixtures and a simple geometric mixing model related to the stretching and thinning of monophase domains. Second, we describe a grain-switching mechanism that is driven by the surface-tension driven migration of newly formed interphase triple junctions. Unlike dynamic recrystallization, which occurs at relatively small strains, both phase mixing mechanisms described here appear to require extremely large strains, a prediction that is consistent with geologic observations. These data suggest that ductile shear zones experience long, transient intervals of microstructural evolution during which rheology is not at steady state. Microstructural damage may be interpreted as the product of several interconnected physical processes, which are collectively essential to the preservation of long-lived, Earth-like plate tectonics.

Single-layer model to predict the source/sink behavior of diffusion-controlled building materials.

PubMed

Kumar, Deept; Little, John C

2003-09-01

Building materials may act as both sources of and sinks forvolatile organic compounds (VOCs) in indoor air. A strategy to characterize the rate of absorption and desorption of VOCs by diffusion-controlled building materials is validated. A previously developed model that predicts mass transfer between a flat slab of material and the well-mixed air within a chamber or room is extended. The generalized model allows a nonuniform initial material-phase concentration and a transient influent gas-phase concentration to be simultaneously considered. An analytical solution to the more general model is developed. Experimental data are obtained by placing samples of vinyl flooring inside a small stainless steel chamber and exposing them to absorption/desorption cycles of n-dodecane and phenol. Measured values for the material-air partition coefficient and the material-phase diffusion coefficient were obtained previously in a series of completely independent experiments. The a priori model predictions are in close agreement with the observed experimental data.

Revealing the Location of the Mixing Layer in a Hot Bubble

NASA Astrophysics Data System (ADS)

Guerrero, M. A.; Fang, X.; Chu, Y.-H.; Toalá, J. A.; Gruendl, R. A.

2017-10-01

The fast stellar winds can blow bubbles in the circumstellar material ejected from previous phases of stellar evolution. These are found at different scales, from planetary nebulae (PNe) around stars evolving to the white dwarf stage, to Wolf-Rayet (WR) bubbles and up to large-scale bubbles around massive star clusters. In all cases, the fast stellar wind is shock-heated and a hot bubble is produced. Processes of mass evaporation and mixing of nebular material and heat conduction occurring at the mixing layer between the hot bubble and the optical nebula are key to determine the thermal structure of these bubbles and their evolution. In this contribution we review our current understanding of the X-ray observations of hot bubbles in PNe and present the first spatially-resolved study of a mixing layer in a PN.

Evaluation of bi-functionalized mesoporous silicas as reversed phase/cation-exchange mixed-mode sorbents for multi-residue solid phase extraction of veterinary drug residues in meat samples.

PubMed

Casado, Natalia; Pérez-Quintanilla, Damián; Morante-Zarcero, Sonia; Sierra, Isabel

2017-04-01

A SBA-15 type mesoporous silica was synthesized and bi-functionalized with octadecylsilane (C18) or octylsilane (C8), and sulfonic acid (SO 3 - ) groups in order to obtain materials with reversed-phase/strong cation-exchange mixed-mode retention mechanism. The resulting hybrid materials (SBA-15-C18-SO 3 - and SBA-15-C8-SO 3 - ) were comprehensively characterized. They showed high surface area, high pore volume and controlled porous size. Elemental analysis of the materials revealed differences in the amount of C18 and C8. SBA-15-C18-SO 3 - contained 0.19mmol/g of C18, while SBA-15-C8-SO 3 - presented 0.54mmol/g of C8. The SO 3 - groups anchored to the silica surface of the pore walls were 0.20 and 0.09mmol/g, respectively. The bi-functionalized materials were evaluated as SPE sorbents for the multi-residue extraction of 26 veterinary drug residues in meat samples using ultra-high-performance liquid chromatography coupled to mass spectrometry detector (UHPLC-MS/MS). Different sorbent amounts (100 and 200mg) and organic solvents were tested to optimize the extraction procedure. Both silicas showed big extraction potential and were successful in the extraction of the target analytes. The mixed-mode retention mechanism was confirmed by comparing both silicas with SBA-15 mesoporous silica mono-functionalized with C18 and C8. Best results were achieved with 200mg of SBA-15-C18-SO 3 - obtaining recoveries higher than 70% for the majority of analytes. Copyright © 2016 Elsevier B.V. All rights reserved.

Observation of Compressible Plasma Mix in Cylindrically Convergent Implosions

NASA Astrophysics Data System (ADS)

Barnes, Cris W.; Batha, Steven H.; Lanier, Nicholas E.; Magelssen, Glenn R.; Tubbs, David L.; Dunne, A. M.; Rothman, Steven R.; Youngs, David L.

2000-10-01

An understanding of hydrodynamic mix in convergent geometry will be of key importance in the development of a robust ignition/burn capability on NIF, LMJ and future pulsed power machines. We have made use of the OMEGA laser facility at the University of Rochester to investigate directly the mix evolution in a convergent geometry, compressible plasma regime. The experiments comprise a plastic cylindrical shell imploded by direct laser irradiation. The cylindrical shell surrounds a lower density plastic foam which provides sufficient back pressure to allow the implosion to stagnate at a sufficiently high radius to permit quantitative radiographic diagnosis of the interface evolution near turnaround. The susceptibility to mix of the shell-foam interface is varied by choosing different density material for the inner shell surface (thus varying the Atwood number). This allows the study of shock-induced Richtmyer-Meshkov growth during the coasting phase, and Rayleigh-Taylor growth during the stagnation phase. The experimental results will be described along with calculational predictions using various radiation hydrodynamics codes and turbulent mix models.

Electronic transport in mixed-phase hydrogenated amorphous/nanocrystalline silicon thin films

NASA Astrophysics Data System (ADS)

Wienkes, Lee Raymond

Interest in mixed-phase silicon thin film materials, composed of an amorphous semiconductor matrix in which nanocrystalline inclusions are embedded, stems in part from potential technological applications, including photovoltaic and thin film transistor technologies. Conventional mixed-phase silicon films are produced in a single plasma reactor, where the conditions of the plasma must be precisely tuned, limiting the ability to adjust the film and nanoparticle parameters independently. The films presented in this thesis are deposited using a novel dual-plasma co-deposition approach in which the nanoparticles are produced separately in an upstream reactor and then injected into a secondary reactor where an amorphous silicon film is being grown. The degree of crystallinity and grain sizes of the films are evaluated using Raman spectroscopy and X-ray diffraction respectively. I describe detailed electronic measurements which reveal three distinct conduction mechanisms in n-type doped mixed-phase amorphous/nanocrystalline silicon thin films over a range of nanocrystallite concentrations and temperatures, covering the transition from fully amorphous to ~30% nanocrystalline. As the temperature is varied from 470 to 10 K, we observe activated conduction, multiphonon hopping (MPH) and Mott variable range hopping (VRH) as the nanocrystal content is increased. The transition from MPH to Mott-VRH hopping around 100K is ascribed to the freeze out of the phonon modes. A conduction model involving the parallel contributions of these three distinct conduction mechanisms is shown to describe both the conductivity and the reduced activation energy data to a high accuracy. Additional support is provided by measurements of thermal equilibration effects and noise spectroscopy, both done above room temperature (>300 K). This thesis provides a clear link between measurement and theory in these complex materials.

Study of thermal stability of Cu{sub 2}Se thermoelectric material

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

Bohra, Anil, E-mail: anilbohra786@gmail.com; Bhatt, Ranu; Bhattacharya, Shovit

2016-05-23

Sustainability of thermoelectric parameter in operating temperature range is a key consideration factor for fabricating thermoelectric generator or cooler. In present work, we have studied the stability of thermoelectric parameter of Cu{sub 2}Se within the temperature range of 50-800°C. Temperature dependent Seebeck coefficients and electrical resistivity measurement are performed under three continuous thermal cycles. X-ray diffraction pattern shows the presence of mixed cubic-monoclinic Cu{sub 2}Se phase in bare pellet which transforms to pure α-Cu{sub 2}Se phase with repeating thermal cycle. Significant enhancement in Seebeck coefficient and electrical resistivity is observed which may be attributed to (i) Se loss observed inmore » EDS and (ii) the phase transformation from mixed cubic-monoclinic structure to pure monoclinic α-Cu{sub 2}Se phase.« less

Boron-Based Hydrogen Storage: Ternary Borides and Beyond

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

Vajo, John J.

DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slowmore » rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.« less

Analysis of High School English Curriculum Materials through Rasch Measurement Model and Maxqda

ERIC Educational Resources Information Center

Batdi, Veli; Elaldi, Senel

2016-01-01

The purpose of the study is to analyze high school English curriculum materials (ECM) through FACETS analysis and MAXQDA-11 programs. The mixed methods approach, both quantitative and qualitative methods, were used in three samples including English teachers in Elazig during the 2014-2015 academic year. While the quantitative phase of the study…

Long-Term Management Strategy for Dredged Material Disposal for Naval Facilities at Pearl Harbor, Hawaii. Phase II - Evaulation of Alternatives

DTIC Science & Technology

2000-03-01

26 Leachate Pathway.................................... 31 Plant Uptake Pathway.................................. 35 Volatization and Odor...Bi13 Appendix C - Surface Runoff Testing............................Cl Appendix D - Leachate Evaluation..............................D1 Appendix E...Oxidized Dredged Material..........................29 Table 7. Mixing Zone Requirement for Runoff Discharges............ 30 Table 8. Leachate Quality

Mixing efficiency inside micro-droplets coalesced by two components in cross-structure

NASA Astrophysics Data System (ADS)

Ren, Yanlin; Liu, Zhaomiao; Pang, Yan

2017-11-01

The mixing of micro-droplets is used in analytical chemistry, medicine production and material synthesis owing to its advantages including the encapsulation and narrow time residence distribution. In this work, droplets are coalesced by two dispersed phase with different flow rates, generated in cross-structure and mixed in planar serpentine structure. The mixing efficiency of micro-droplets under control characters including the width of entrance and the flow rate of dispersed phases have been investigated by experiments and numerical simulations. The UDS (user-defined scalar) as dimensionless concentration of the solution is adopted in simulation, and is used to calculate the concentration and the mixing effect. By changing the flow rates and the entrances` width, the changing rules of the mixing characters have been obtained. The asymmetry distributions of components make rapid mixing process in half part of each droplet when travel through a straight channel. Increasing of the ratio of entrance width result into larger droplet and weaken the chaotic mixing effect. Meanwhile, the coalesced mechanism can be performed by ranging the ratio of flow rates, the ranges are also determined by the widths of entrances. The authors gratefully acknowledge the support of National Natural Science Foundation of China (Grant No. 11572013).

Structure and properties of hybrid composite materials

NASA Astrophysics Data System (ADS)

Chernyshova, T. A.; Kobeleva, L. I.; Bolotova, L. K.; Katin, I. V.

2013-03-01

The structure and interfacial interaction are studied in the hybrid aluminum-matrix composite materials fabricated by reactive casting combined with mechanical mixing of fillers with a metallic melt. The following types of hardening are considered: hardening by ceramic particles and by the phases formed as isolated inclusions or coatings on ceramic particles during in situ reactions. The hardness and tribological properties of the composite materials as functions of their compositions are discussed.

Analysis and Simulation of Hypervelocity Gouging Impacts

DTIC Science & Technology

2006-06-01

iron. The iron EOS is considered very accurate for low carbon steels , like 1080 steel - and includes the phase transitions that occur at high pressure...tests) deposited on top of martensitic 1080 steel (the rail material). The presence of martensite in the 1080 steel demonstrated that the temperatures...turn it into martensite . 2-6 Gerstle also found shoe material (stainless steel ) in the examined rail section. This indicated material mixing that is

Lyotropic liquid crystalline L3 phase silicated nanoporous monolithic composites and their production

DOEpatents

McGrath, Kathryn M.; Dabbs, Daniel M.; Aksay, Ilhan A.; Gruner, Sol M.

2003-10-28

A mesoporous ceramic material is provided having a pore size diameter in the range of about 10-100 nanometers produced by templating with a ceramic precursor a lyotropic liquid crystalline L.sub.3 phase consisting of a three-dimensional, random, nonperiodic network packing of a multiple connected continuous membrane. A preferred process for producing the inesoporous ceramic material includes producing a template of a lyotropic liquid crystalline L.sub.3 phase by mixing a surfactant, a co-surfactant and hydrochloric acid, coating the template with an inorganic ceramic precursor by adding to the L.sub.3 phase tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS) and then converting the coated template to a ceramic by removing any remaining liquids.

Reactive ion etching effects on carbon-doped Ge2Sb2Te5 phase change material in CF4/Ar plasma

NASA Astrophysics Data System (ADS)

Shen, Lanlan; Song, Sannian; Song, Zhitang; Li, Le; Guo, Tianqi; Liu, Bo; Wu, Liangcai; Cheng, Yan; Feng, Songlin

2016-10-01

Recently, carbon-doped Ge2Sb2Te5 (CGST) has been proved to be a high promising material for future phase change memory technology. In this article, reactive ion etching (RIE) of phase change material CGST films is studied using CF4/Ar gas mixture. The effects on gas-mixing ratio, RF power, gas pressure on the etch rate, etch profile and roughness of the CGST film are investigated. Conventional phase change material Ge2Sb2Te5 (GST) films are simultaneously studied for comparison. Compared with GST film, 10 % more CF4 is needed for high etch rate and 10% less CF4 for good anisotropy of CGST due to more fluorocarbon polymer deposition during CF4 etching. The trends of etch rates and roughness of CGST with varying RF power and chamber pressure are similar with those of GST. Furthermore, the etch rate of CGST are more easily to be saturated when higher RF power is applied.

Dowel Bar Retrofit Mix Design and Specification

DOT National Transportation Integrated Search

2012-02-01

The focus of this project was on identifying critical properties that control longterm performance of repair concrete, especially rapidsetting : materials extended using pea gravel (maximum size aggregate 9.5 mm). : In the first phase of this proj...

Fabrication and Properties of Micro-Nanoencapsulated Phase Change Materials for Internally-Cooled Liquid Desiccant Dehumidification.

PubMed

Niu, Xiaofeng; Xu, Qing; Zhang, Yi; Zhang, Yue; Yan, Yufeng; Liu, Tao

2017-04-29

Micro-nanoencapsulated phase change materials (M-NEPCMs) are proposed to be useful in liquid desiccant dehumidification by restraining the temperature rise in the moisture-removal process and improving the dehumidification efficiency. In this paper, the n -octadecane M-NEPCMs with desirable thermal properties for internally-cooled dehumidification were fabricated by using compound emulsifiers through the in-situ polymerization method. Melamine-formaldehyde resin was used as the shell material. The effects of the mixing ratio, emulsification methods and amount of the compound emulsifiers on the morphology, size and thermal properties of the M-NEPCMs were investigated experimentally. The optimum weight mixing ratio of the compound emulsifiers is SDS (sodium dodecyl sulfate):Tween80 (polyoxyethylene sorbitan monooleate):Span80 (sorbitan monooleate) = 0.1:0.6:0.3, which achieves the best stability of the n -octadecane emulsion. When the compound emulsifiers are 10 wt. % of the core material, the melting enthalpy of M-NEPCMs reaches its maximum of 145.26 J/g of capsules, with an encapsulation efficiency of 62.88% and a mean diameter of 636 nm. The sub-cooling of the prepared M-NEPCMs is lower than 3 °C, with an acceptable thermal reliability after the thermal cycling test. A pre-emulsification prior to the addition of deionized water in the emulsification is beneficial to the morphology of the capsules, as the phase change enthalpy can be increased by 123.7%.

Dielectric properties of novel polyurethane-PZT-graphite foam composites

NASA Astrophysics Data System (ADS)

Tolvanen, Jarkko; Hannu, Jari; Nelo, Mikko; Juuti, Jari; Jantunen, Heli

2016-09-01

Flexible foam composite materials offer multiple benefits to future electronic applications as the rapid development of the electronics industry requires smaller, more efficient, and lighter materials to further develop foldable and wearable applications. The aims of this work were to examine the electrical properties of three- and four-phase novel foam composites in different conditions, find the optimal mixture for four-phase foam composites, and study the combined effects of lead zirconate titanate (PZT) and graphite fillers. The flexible and highly compressible foams were prepared in a room-temperature mixing process using polyurethane, PZT, and graphite components as well as their combinations, in which air acted as one phase. In three-phase foams the amount of PZT varied between 20 and 80 wt% and the amount of graphite, between 1 and 15 wt%. The four-phase foams were formed by adding 40 wt% of PZT while the amount of graphite ranged between 1 and 15 wt%. The presented results and materials could be utilized to develop new flexible and soft sensor applications by means of material technology.

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

Holder, Aaron M.; Siol, Sebastian; Ndione, Paul F.

Structure and composition control the behavior of materials. Isostructural alloying is historically an extremely successful approach for tuning materials properties, but it is often limited by binodal and spinodal decomposition, which correspond to the thermodynamic solubility limit and the stability against composition fluctuations, respectively. We show that heterostructural alloys can exhibit a markedly increased range of metastable alloy compositions between the binodal and spinodal lines, thereby opening up a vast phase space for novel homogeneous single-phase alloys. We distinguish two types of heterostructural alloys, that is, those between commensurate and incommensurate phases. Because of the structural transition around the criticalmore » composition, the properties change in a highly nonlinear or even discontinuous fashion, providing a mechanism for materials design that does not exist in conventional isostructural alloys. The novel phase diagram behavior follows from standard alloy models using mixing enthalpies from first-principles calculations. Furthermore, thin-film deposition demonstrates the viability of the synthesis of these metastable single-phase domains and validates the computationally predicted phase separation mechanism above the upper temperature bound of the nonequilibrium single-phase region.« less

Monitoring bisphosphonate surface functionalization and acid stability of hierarchically porous titanium zirconium oxides.

PubMed

Ide, Andreas; Drisko, Glenna L; Scales, Nicholas; Luca, Vittorio; Schiesser, Carl H; Caruso, Rachel A

2011-11-01

To take advantage of the full potential of functionalized transition metal oxides, a well-understood nonsilane based grafting technique is required. The functionalization of mixed titanium zirconium oxides was studied in detail using a bisphosphonic acid, featuring two phosphonic acid groups with high surface affinity. The bisphosphonic acid employed was coupled to a UV active benzamide moiety in order to track the progress of the surface functionalization in situ. Using different material compositions, altering the pH environment, and looking at various annealing conditions, key features of the functionalization process were identified that consequently will allow for intelligent material design. Loading with bisphosphonic acid was highest on supports calcined at 650 °C compared to lower calcination temperatures: A maximum capacity of 0.13 mmol g(-1) was obtained and the adsorption process could be modeled with a pseudo-second-order rate relationship. Heating at 650 °C resulted in a phase transition of the mixed binary oxide to a ternary oxide, titanium zirconium oxide in the srilankite phase. This phase transition was crucial in order to achieve high loading of the bisphosphonic acid and enhanced chemical stability in highly acidic solutions. Due to the inert nature of phosphorus-oxygen-metal bonds, materials functionalized by bisphosphonic acids showed increased chemical stability compared to their nonfunctionalized counterparts in harshly acidic solutions. Leaching studies showed that the acid stability of the functionalized material was improved with a partially crystalline srilankite phase. The materials were characterized using nitrogen sorption, X-ray powder diffraction, and UV-vis spectroscopy; X-ray photoelectron spectroscopy was used to study surface coverage with the bisphosphonic acid molecules.

Fundamental Physics

NASA Image and Video Library

2003-01-22

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy.

PubMed

Masters, Robert C; Pearson, Andrew J; Glen, Tom S; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M; Lidzey, David G; Rodenburg, Cornelia

2015-04-24

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.

Mimicking electrodeposition in the gas phase: a programmable concept for selected-area fabrication of multimaterial nanostructures.

PubMed

Cole, Jesse J; Lin, En-Chiang; Barry, Chad R; Jacobs, Heiko O

2010-05-21

An in situ gas-phase process that produces charged streams of Au, Si, TiO(2), ZnO, and Ge nanoparticles/clusters is reported together with a programmable concept for selected-area assembly/printing of more than one material type. The gas-phase process mimics solution electrodeposition whereby ions in the liquid phase are replaced with charged clusters in the gas phase. The pressure range in which the analogy applies is discussed and it is demonstrated that particles can be plated into pores vertically (minimum resolution 60 nm) or laterally to form low-resistivity (48 microOmega cm) interconnects. The process is applied to the formation of multimaterial nanoparticle films and sensors. The system works at atmospheric pressure and deposits material at room temperature onto electrically biased substrate regions. The combination of pumpless operation and parallel nozzle-free deposition provides a scalable tool for printable flexible electronics and the capability to mix and match materials.

Movie of phase separation during physics of colloids in space experiment

NASA Technical Reports Server (NTRS)

2002-01-01

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area in the video is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Phase separation during the Experiment on Physics of Colloids in Space

NASA Technical Reports Server (NTRS)

2003-01-01

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Platform construction and extraction mechanism study of magnetic mixed hemimicelles solid-phase extraction

NASA Astrophysics Data System (ADS)

Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua

2016-12-01

Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples.

Gravity and Granular Materials

NASA Technical Reports Server (NTRS)

Behringer, R. P.; Hovell, Daniel; Kondic, Lou; Tennakoon, Sarath; Veje, Christian

1999-01-01

We describe experiments that probe a number of different types of granular flow where either gravity is effectively eliminated or it is modulated in time. These experiments include the shaking of granular materials both vertically and horizontally, and the shearing of a 2D granular material. For the shaken system, we identify interesting dynamical phenomena and relate them to standard simple friction models. An interesting application of this set of experiments is to the mixing of dissimilar materials. For the sheared system we identify a new kind of dynamical phase transition.

Method of synthesizing a low density material

DOEpatents

Lorensen, L.E.; Monaco, S.B.

1987-02-27

A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.

Secondary battery material and synthesis method

DOEpatents

Liu, Hongjian; Kepler, Keith Douglas; Wang, Yu

2013-10-22

A composite Li.sub.1+xMn.sub.2-x-yM.sub.yO.sub.4 cathode material stabilized by treatment with a second transition metal oxide phase that is highly suitable for use in high power and energy density Li-ion cells and batteries. A method for treating a Li.sub.1+xMn.sub.2-x-yM.sub.yO.sub.4 cathode material utilizing a dry mixing and firing process.

Moisture sensitivity of hot mix asphalt (HMA) mixtures in Nebraska : phase II.

DOT National Transportation Integrated Search

2009-12-01

As a consequential effort to the previous NDOR research project (P564) on moisture damage, this report presents : outcomes from this project incorporated with the previous project. Performance changes and fundamental material : characteristics associ...

Cold in-place recycle phase III, mix design.

DOT National Transportation Integrated Search

2014-10-01

This projects purpose is to revise the UDOT accepted design methods for Cold In-Place Recycling so that they : better reflect field behavior and target the desirable attributes of the material. The previous design process failed to : adequately pr...

Automated first-principles mapping for phase-change materials.

PubMed

Esser, Marc; Maintz, Stefan; Dronskowski, Richard

2017-04-05

Plotting materials on bi-coordinate maps according to physically meaningful descriptors has a successful tradition in computational solid-state science spanning more than four decades. Equipped with new ab initio techniques introduced in this work, we generate an improved version of the treasure map for phase-change materials (PCMs) as introduced previously by Lencer et al. which, other than before, charts all industrially used PCMs correctly. Furthermore, we suggest seven new PCM candidates, namely SiSb 4 Te 7 , Si 2 Sb 2 Te 5 , SiAs 2 Te 4 , PbAs 2 Te 4 , SiSb 2 Te 4 , Sn 2 As 2 Te 5 , and PbAs 4 Te 7 , to be used as synthetic targets. To realize aforementioned maps based on orbital mixing (or "hybridization") and ionicity coordinates, structural information was first included into an ab initio numerical descriptor for sp 3 orbital mixing and then generalized beyond high-symmetry structures. In addition, a simple, yet powerful quantum-mechanical ionization measure also including structural information was introduced. Taken together, these tools allow for (automatically) generating materials maps solely relying on first-principles calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Microstructures of tribologically modified surface layers in two-phase alloys

NASA Astrophysics Data System (ADS)

Figueroa, C. G.; Ortega, I.; Jacobo, V. H.; Ortiz, A.; Bravo, A. E.; Schouwenaars, R.

2014-08-01

When ductile alloys are subject to sliding wear, small increments of plastic strain accumulate into severe plastic deformation and mechanical alloying of the surface layer. The authors constructed a simple coaxial tribometer, which was used to study this phenomenon in wrought Al-Sn and cast Cu-Mg-Sn alloys. The first class of materials is ductile and consists of two immiscible phases. Tribological modification is observed in the form of a transition zone from virgin material to severely deformed grains. At the surface, mechanical mixing of both phases competes with diffusional unmixing. Vortex flow patterns are typically observed. The experimental Cu-Mg-Sn alloys are ductile for Mg-contents up to 2 wt% and consist of a- dendrites with a eutectic consisting of a brittle Cu2Mg-matrix with α-particles. In these, the observations are similar to the Al-Sn Alloys. Alloys with 5 wt% Mg are brittle due to the contiguity of the eutectic compound. Nonetheless, under sliding contact, this compound behaves in a ductile manner, showing mechanical mixing of a and Cu2Mg in the top layers and a remarkable transition from a eutectic to cellular microstructure just below, due to severe shear deformation. AFM-observations allow identifying the mechanically homogenized surface layers as a nanocrystalline material with a cell structure associated to the sliding direction.

Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions

NASA Astrophysics Data System (ADS)

Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.

2015-08-01

Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead, they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance and, therefore, particles prepared in this study should mimic atmospheric mixed-phase aerosol particles. Some results of this study tend to be in agreement with previous microscopy experiments, but others, such as phase separation properties of 1,2,6-hexanetriol, do not agree with previous work. Because the particles studied in this experiment are of a smaller size than those used in microscopy studies, the discrepancies found could be a size-related effect.

Second order harmonic guided wave mutual interactions in plate: Vector analysis, numerical simulation, and experimental results

NASA Astrophysics Data System (ADS)

Hasanian, Mostafa; Lissenden, Cliff J.

2017-08-01

The extraordinary sensitivity of nonlinear ultrasonic waves to the early stages of material degradation makes them excellent candidates for nondestructive material characterization. However, distinguishing weak material nonlinearity from instrumentation nonlinearity remains problematic for second harmonic generation approaches. A solution to this problem is to mix waves having different frequencies and to let their mutual interaction generate sum and difference harmonics at frequencies far from those of the instrumentation. Mixing of bulk waves and surface waves has been researched for some time, but mixing of guided waves has not yet been investigated in depth. A unique aspect of guided waves is their dispersive nature, which means we need to assure that a wave can propagate at the sum or difference frequency. A wave vector analysis is conducted that enables selection of primary waves traveling in any direction that generate phase matched secondary waves. We have tabulated many sets of primary waves and phase matched sum and difference harmonics. An example wave mode triplet of two counter-propagating collinear shear horizontal waves that interact to generate a symmetric Lamb wave at the sum frequency is simulated using finite element analysis and then laboratory experiments are conducted. The finite element simulation eliminates issues associated with instrumentation nonlinearities and signal-to-noise ratio. A straightforward subtraction method is used in the experiments to identify the material nonlinearity induced mutual interaction and show that the generated Lamb wave propagates on its own and is large enough to measure. Since the Lamb wave has different polarity than the shear horizontal waves the material nonlinearity is clearly identifiable. Thus, the mutual interactions of shear horizontal waves in plates could enable volumetric characterization of material in remote regions from transducers mounted on just one side of the plate.

Method for producing catalysis from coal

DOEpatents

Farcasiu, Malvina; Derbyshire, Frank; Kaufman, Phillip B.; Jagtoyen, Marit

1998-01-01

A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere.

Method for producing catalysts from coal

DOEpatents

Farcasiu, M.; Derbyshire, F.; Kaufman, P.B.; Jagtoyen, M.

1998-02-24

A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere. 1 fig.

Inorganic metal oxide/organic polymer nanocomposites and method thereof

DOEpatents

Gash, Alexander E.; Satcher, Joe H.; Simpson, Randy

2004-03-30

A synthetic method for preparation of hybrid inorganic/organic energetic nanocomposites is disclosed herein. The method employs the use of stable metal inorganic salts and organic solvents as well as an organic polymer with good solubility in the solvent system to produce novel nanocomposite energetic materials. In addition, fuel metal powders (particularly those that are oxophillic) can be incorporated into composition. This material has been characterized by thermal methods, energy-filtered transmission electron microscopy (EFTEM), N.sub.2 adsoprtion/desorption methods, and Fourier-Transform (FT-IR) spectroscopy. According to these characterization methods the organic polymer phase fills the nanopores of the composite material, providing superb mixing of the component phases in the energetic nanocomposite.

Inorganic Metal Oxide/Organic Polymer Nanocomposites And Method Thereof

DOEpatents

Gash, Alexander E.; Satcher, Joe H.; Simpson, Randy

2004-11-16

A synthetic method for preparation of hybrid inorganic/organic energetic nanocomposites is disclosed herein. The method employs the use of stable metal in organic salts and organic solvents as well as an organic polymer with good solubility in the solvent system to produce novel nanocomposite energetic materials. In addition, fuel metal powders (particularly those that are oxophilic) can be incorporated into composition. This material has been characterized by thermal methods, energy-filtered transmission electron microscopy (EFTEM), N.sub.2 adsoprtion/desorption methods, and Fourier-Transform (FT-IR) spectroscopy. According to these characterization methods the organic polymer phase fills the nanopores of the material, providing superb mixing of the component phases in the energetic nanocomposite.

Phase Equilibria Diagrams Database

National Institute of Standards and Technology Data Gateway

SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

Synthesis of Mixed Cu/Ce Oxide Nanoparticles by the Oil-in-Water Microemulsion Reaction Method.

PubMed

Pemartin-Biernath, Kelly; Vela-González, Andrea V; Moreno-Trejo, Maira B; Leyva-Porras, César; Castañeda-Reyna, Iván E; Juárez-Ramírez, Isaías; Solans, Conxita; Sánchez-Domínguez, Margarita

2016-06-16

Cerium oxide and mixed Cu/Ce oxide nanoparticles were prepared by the oil-in-water (O/W) microemulsion reaction method in mild conditions. The Cu/Ce molar ratio was varied between 0/100 and 50/50. According to X-ray diffraction (XRD), below 30/70 Cu/Ce molar ratio, the materials presented a single phase consistent with cubic fluorite CeO₂. However, above Cu/Ce molar ratio 30/70, an excess monoclinic CuO phase in coexistence with the predominant Cu/Ce mixed oxide was detected by XRD and High-Resolution Transmission Electron Microscopy (HRTEM). Raman spectroscopy showed that oxygen vacancies increased significantly as the Cu content was increased. Band gap ( E g ) was investigated as a function of the Cu/Ce molar ratio, resulting in values from 2.91 eV for CeO₂ to 2.32 eV for the mixed oxide with 30/70 Cu/Ce molar ratio. These results indicate that below 30/70 Cu/Ce molar ratio, Cu 2+ is at least partially incorporated into the ceria lattice and very well dispersed in general. In addition, the photodegradation of Indigo Carmine dye under visible light irradiation was explored for selected samples; it was shown that these materials can remove such contaminants, either by adsorption and/or photodegradation. The results obtained will encourage investigation into the optical and photocatalytic properties of these mixed oxides, for widening their potential applications.

Synthesis of Mixed Cu/Ce Oxide Nanoparticles by the Oil-in-Water Microemulsion Reaction Method

PubMed Central

Pemartin-Biernath, Kelly; Vela-González, Andrea V.; Moreno-Trejo, Maira B.; Leyva-Porras, César; Castañeda-Reyna, Iván E.; Juárez-Ramírez, Isaías; Solans, Conxita; Sánchez-Domínguez, Margarita

2016-01-01

Cerium oxide and mixed Cu/Ce oxide nanoparticles were prepared by the oil-in-water (O/W) microemulsion reaction method in mild conditions. The Cu/Ce molar ratio was varied between 0/100 and 50/50. According to X-ray diffraction (XRD), below 30/70 Cu/Ce molar ratio, the materials presented a single phase consistent with cubic fluorite CeO2. However, above Cu/Ce molar ratio 30/70, an excess monoclinic CuO phase in coexistence with the predominant Cu/Ce mixed oxide was detected by XRD and High-Resolution Transmission Electron Microscopy (HRTEM). Raman spectroscopy showed that oxygen vacancies increased significantly as the Cu content was increased. Band gap (Eg) was investigated as a function of the Cu/Ce molar ratio, resulting in values from 2.91 eV for CeO2 to 2.32 eV for the mixed oxide with 30/70 Cu/Ce molar ratio. These results indicate that below 30/70 Cu/Ce molar ratio, Cu2+ is at least partially incorporated into the ceria lattice and very well dispersed in general. In addition, the photodegradation of Indigo Carmine dye under visible light irradiation was explored for selected samples; it was shown that these materials can remove such contaminants, either by adsorption and/or photodegradation. The results obtained will encourage investigation into the optical and photocatalytic properties of these mixed oxides, for widening their potential applications. PMID:28773602

Sub-nanometre resolution imaging of polymer–fullerene photovoltaic blends using energy-filtered scanning electron microscopy

PubMed Central

Masters, Robert C.; Pearson, Andrew J.; Glen, Tom S.; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M.; Lidzey, David G.; Rodenburg, Cornelia

2015-01-01

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. PMID:25906738

First principles study of surface stability and segregation of PdRuRh ternary metal alloy system

NASA Astrophysics Data System (ADS)

Aspera, Susan Meñez; Arevalo, Ryan Lacdao; Nakanishi, Hiroshi; Kasai, Hideaki

2018-05-01

The recognized importance on the studies of alloyed materials is due to the high possibility of forming designer materials that caters to different applications. In any reaction and application, the stability and configuration of the alloy combination are important. In this study, we analyzed the surface stability and segregation of ternary metal alloy system PdRuRh through first principles calculation using density functional theory (DFT). We considered the possibility of forming phases as observed in the binary combinations of elements, i.e., completely miscible, and separating phases. With that, the model we analyzed for the ternary metal alloy slabs considers forming complete atomic miscibility, segregation of each component, and segregation of one component with mixing of the two other. Our results show that for the ternary combination of Pd, Rh and Ru, the Pd atoms have high tendency to segregate at the surface, while due to the high tendency of Ru and Rh to mix, core formation of a mixed RuRh is possible. Also, we determined that the trend of stability in the binary alloy system is a good determinant of stability in the ternary alloy system.

Tamping Mortars with Stabilizing and Plasticizing Admixtures

NASA Astrophysics Data System (ADS)

Terlyha, Volodymir; Sobol, Khrystyna

2012-06-01

Boreholes cementing operations at the depth of several kilometers requires the best technology as well as the best materials. To produce the materials satisfying all the requirements concerning the tamping works is possible using the technology of dry building mixes (DBM) prepared at the factories by thorough mixing of accurately dosed components. Using of chemical admixtures allows improving some properties of these mixes. In this work the influence of mineral fillers and chemical admixtures on the properties of the fresh mixture and hardened tamping mortar was investigated. It is established that introduction of the admixture with complex action on the basis of stabilizer Walocel 15-01 and plasticizer Melflux 2651 allows obtaining the fresh mixture with high spreadability. At the same time the value of dehydration approaches to zero which favorably effects on stabilization of fresh mixture and not allows the sedimentation processes to take place. By the X-ray analysis, the positive influence of modification admixtures on the hydration processes in the tamping mortars by activating them was identified. In the result of this, the formation of hydrate phases is accelerated; these phases tightly mud the pore area of tamping stone increasing by this its strength.

Understanding Chemical Equilibrium: The Role of Gas Phases and Mixing Contributions in the Minimum of Free Energy Plots

ERIC Educational Resources Information Center

Tomba, J. Pablo

2017-01-01

The use of free energy plots to understand the concept of thermodynamic equilibrium has been shown to be of great pedagogical value in materials science. Although chemical equilibrium is also amenable to this kind of analysis, it is not part of the agenda of materials science textbooks. Something similar is found in chemistry branches, where free…

Fabrication and Properties of Micro-Nanoencapsulated Phase Change Materials for Internally-Cooled Liquid Desiccant Dehumidification

PubMed Central

Niu, Xiaofeng; Xu, Qing; Zhang, Yi; Zhang, Yue; Yan, Yufeng; Liu, Tao

2017-01-01

Micro-nanoencapsulated phase change materials (M-NEPCMs) are proposed to be useful in liquid desiccant dehumidification by restraining the temperature rise in the moisture-removal process and improving the dehumidification efficiency. In this paper, the n-octadecane M-NEPCMs with desirable thermal properties for internally-cooled dehumidification were fabricated by using compound emulsifiers through the in-situ polymerization method. Melamine-formaldehyde resin was used as the shell material. The effects of the mixing ratio, emulsification methods and amount of the compound emulsifiers on the morphology, size and thermal properties of the M-NEPCMs were investigated experimentally. The optimum weight mixing ratio of the compound emulsifiers is SDS (sodium dodecyl sulfate):Tween80 (polyoxyethylene sorbitan monooleate):Span80 (sorbitan monooleate) = 0.1:0.6:0.3, which achieves the best stability of the n-octadecane emulsion. When the compound emulsifiers are 10 wt. % of the core material, the melting enthalpy of M-NEPCMs reaches its maximum of 145.26 J/g of capsules, with an encapsulation efficiency of 62.88% and a mean diameter of 636 nm. The sub-cooling of the prepared M-NEPCMs is lower than 3 °C, with an acceptable thermal reliability after the thermal cycling test. A pre-emulsification prior to the addition of deionized water in the emulsification is beneficial to the morphology of the capsules, as the phase change enthalpy can be increased by 123.7%. PMID:28468282

Molecular Interaction Control in Diblock Copolymer Blends and Multiblock Copolymers with Opposite Phase Behaviors

NASA Astrophysics Data System (ADS)

Cho, Junhan

2014-03-01

Here we show how to control molecular interactions via mixing AB and AC diblock copolymers, where one copolymer exhibits upper order-disorder transition and the other does lower disorder-order transition. Linear ABC triblock copolymers possessing both barotropic and baroplastic pairs are also taken into account. A recently developed random-phase approximation (RPA) theory and the self-consistent field theory (SCFT) for general compressible mixtures are used to analyze stability criteria and morphologies for the given systems. It is demonstrated that the copolymer systems can yield a variety of phase behaviors in their temperature and pressure dependence upon proper mixing conditions and compositions, which is caused by the delicate force fields generated in the systems. We acknowledge the financial support from National Research Foundation of Korea and Center for Photofunctional Energy Materials.

Synthesis and characterization of a mixed phase of anatase TiO2 and TiO2(B) by low pressure chemical vapour deposition (LPCVD) for high photocatalytic activity

NASA Astrophysics Data System (ADS)

Chimupala, Y.; Hyett, G.; Simpson, R.; Brydson, R.

2014-06-01

This project is concerned with enhancing photocatalytic activity by preparing a mixed phase of nano-sized TiO2. TiO2 thin films were synthesized by using Low Pressure Chemical Vapour Deposition (LPCVD). Titanium isopropoxide and N2 gas were used as the precursor and carrier gas respectively. The effects of reaction temperature, carrier gas flow rate and deposited area were studied. TiO2 thin films with nano-sized TiO2 particles were obtained under suitable conditions and SEM, TEM, powder XRD and Raman spectroscopy were employed to characterize the phase and physical appearance of synthesized materials. Preliminary results show that a dual phase (TiO2(B) and anatase) thin film nanopowder was successfully prepared by LPCVD with needle- and polygonal plate-shape crystallites respectively. This thin film deposit produced a preferred orientation of TiO2(B) needles in the [001] direction of average crystallite size 50-80 nm in length and 5-10 nm in width, whilst the crystallite size of anatase polygonal-plates was around 200 nm. The optimal LPCVD condition for preparing this mixed phase of TiO2 was 600°C with a 1 mL/s N2 flow rate.

Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1988-01-01

Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

Hygroscopic and phase separation properties of ammonium sulfate/organic/water ternary solutions

NASA Astrophysics Data System (ADS)

Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.

2015-03-01

Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Deliquescence and efflorescence of simple inorganic salt particles have been investigated by a variety of methods, such as IR spectroscopy, tandem mobility analysis and electrodynamic balance. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Many recent studies have focused on microscopy techniques that require deposition of the aerosol on a glass slide, possibly changing its surface properties. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance, and therefore, particles prepared in this study should mimic atmospheric mixed phase aerosol particles. The results of this study tend to be in agreement with previous microscopy experiments, with several key differences, which possibly reveal a size-dependent effect on phase separation in organic/inorganic aerosol particles.

Phase formation and UV luminescence of Gd3+ doped perovskite-type YScO3

NASA Astrophysics Data System (ADS)

Shimizu, Yuhei; Ueda, Kazushige

2016-10-01

Synthesis of pure and Gd3+doped perovskite-type YScO3 was attempted by a polymerized complex (PC) method and solid state reaction (SSR) method. Crystalline phases and UV luminescence of samples were examined with varying heating temperatures. The perovskite-type single phase was not simply formed in the SSR method, as reported in some literatures, and two cubic C-type phases of starting oxide materials remained forming slightly mixed solid solutions. UV luminescence of Gd3+ doped samples increased with an increase in heating temperatures and volume of the perovskite-type phase. In contrast, a non-crystalline precursor was crystallized to a single C-type phase at 800 °C in the PC method forming a completely mixed solid solution. Then, the phase of perovskite-type YScO3 formed at 1200 °C and its single phase was obtained at 1400 °C. It was revealed that high homogeneousness of cations was essential to generate the single perovskite-phase of YScO3. Because Gd3+ ions were also dissolved into the single C-type phase in Gd3+ doped samples, intense UV luminescence was observed above 800 °C in both C-type phase and perovskite-type phase.

Thermal transport in binary colloidal glasses: Composition dependence and percolation assessment

NASA Astrophysics Data System (ADS)

Ruckdeschel, Pia; Philipp, Alexandra; Kopera, Bernd A. F.; Bitterlich, Flora; Dulle, Martin; Pech-May, Nelson W.; Retsch, Markus

2018-02-01

The combination of various types of materials is often used to create superior composites that outperform the pure phase components. For any rational design, the thermal conductivity of the composite as a function of the volume fraction of the filler component needs to be known. When approaching the nanoscale, the homogeneous mixture of various components poses an additional challenge. Here, we investigate binary nanocomposite materials based on polymer latex beads and hollow silica nanoparticles. These form randomly mixed colloidal glasses on a sub-μ m scale. We focus on the heat transport properties through such binary assembly structures. The thermal conductivity can be well described by the effective medium theory. However, film formation of the soft polymer component leads to phase segregation and a mismatch between existing mixing models. We confirm our experimental data by finite element modeling. This additionally allowed us to assess the onset of thermal transport percolation in such random particulate structures. Our study contributes to a better understanding of thermal transport through heterostructured particulate assemblies.

Improving Mixed-phase Cloud Parameterization in Climate Model with the ACRF Measurements

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

Wang, Zhien

Mixed-phase cloud microphysical and dynamical processes are still poorly understood, and their representation in GCMs is a major source of uncertainties in overall cloud feedback in GCMs. Thus improving mixed-phase cloud parameterizations in climate models is critical to reducing the climate forecast uncertainties. This study aims at providing improved knowledge of mixed-phase cloud properties from the long-term ACRF observations and improving mixed-phase clouds simulations in the NCAR Community Atmosphere Model version 5 (CAM5). The key accomplishments are: 1) An improved retrieval algorithm was developed to provide liquid droplet concentration for drizzling or mixed-phase stratiform clouds. 2) A new ice concentrationmore » retrieval algorithm for stratiform mixed-phase clouds was developed. 3) A strong seasonal aerosol impact on ice generation in Arctic mixed-phase clouds was identified, which is mainly attributed to the high dust occurrence during the spring season. 4) A suite of multi-senor algorithms was applied to long-term ARM observations at the Barrow site to provide a complete dataset (LWC and effective radius profile for liquid phase, and IWC, Dge profiles and ice concentration for ice phase) to characterize Arctic stratiform mixed-phase clouds. This multi-year stratiform mixed-phase cloud dataset provides necessary information to study related processes, evaluate model stratiform mixed-phase cloud simulations, and improve model stratiform mixed-phase cloud parameterization. 5). A new in situ data analysis method was developed to quantify liquid mass partition in convective mixed-phase clouds. For the first time, we reliably compared liquid mass partitions in stratiform and convective mixed-phase clouds. Due to the different dynamics in stratiform and convective mixed-phase clouds, the temperature dependencies of liquid mass partitions are significantly different due to much higher ice concentrations in convective mixed phase clouds. 6) Systematic evaluations of mixed-phase cloud simulations by CAM5 were performed. Measurement results indicate that ice concentrations control stratiform mixed-phase cloud properties. The improvement of ice concentration parameterization in the CAM5 was done in close collaboration with Dr. Xiaohong Liu, PNNL (now at University of Wyoming).« less

Strain-gradient-induced magnetic anisotropy in straight-stripe mixed-phase bismuth ferrites: Insight into flexomagnetism

NASA Astrophysics Data System (ADS)

Lee, Jin Hong; Kim, Kwang-Eun; Jang, Byung-Kweon; Ünal, Ahmet A.; Valencia, Sergio; Kronast, Florian; Ko, Kyung-Tae; Kowarik, Stefan; Seidel, Jan; Yang, Chan-Ho

2017-08-01

Implementation of antiferromagnetic compounds as active elements in spintronics has been hindered by their insensitive nature against external perturbations which causes difficulties in switching among different antiferromagnetic spin configurations. Electrically controllable strain gradient can become a key parameter to tune the antiferromagnetic states of multiferroic materials. We have discovered a correlation between an electrically written straight-stripe mixed-phase boundary and an in-plane antiferromagnetic spin axis in highly elongated La-5%-doped BiFe O3 thin films by performing polarization-dependent photoemission electron microscopy in conjunction with cluster model calculations. A model Hamiltonian calculation for the single-ion anisotropy including the spin-orbit interaction has been performed to figure out the physical origin of the link between the strain gradient present in the mixed-phase area and its antiferromagnetic spin axis. Our findings enable estimation of the strain-gradient-induced magnetic anisotropy energy per Fe ion at around 5 ×10-12eV m , and provide a pathway toward an electric-field-induced 90° rotation of antiferromagnetic spin axis at room temperature by flexomagnetism.

Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

DOE PAGES

Lin, Ye; Fang, Shumin; Su, Dong; ...

2015-04-10

Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce 0.8Gd 0.2O 2₋δ–CoFe 2O 4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopantmore » and depletion of oxygen vacancies at the Ce 0.8Gd 0.2O 2₋δ–Ce 0.8Gd 0.2O 2₋δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. Lastly, this work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution.« less

Platform construction and extraction mechanism study of magnetic mixed hemimicelles solid-phase extraction

PubMed Central

Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua

2016-01-01

Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples. PMID:27924944

Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

PubMed Central

Lin, Ye; Fang, Shumin; Su, Dong; Brinkman, Kyle S; Chen, Fanglin

2015-01-01

Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce0.8Gd0.2O2−δ–CoFe2O4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopant and depletion of oxygen vacancies at the Ce0.8Gd0.2O2−δ–Ce0.8Gd0.2O2−δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. This work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution. PMID:25857355

Enhancing grain boundary ionic conductivity in mixed ionic-electronic conductors.

PubMed

Lin, Ye; Fang, Shumin; Su, Dong; Brinkman, Kyle S; Chen, Fanglin

2015-04-10

Mixed ionic-electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce0.8Gd0.2O2-δ-CoFe2O4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopant and depletion of oxygen vacancies at the Ce0.8Gd0.2O2-δ-Ce0.8Gd0.2O2-δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. This work illustrates the control of mesoscale level transport properties in mixed ionic-electronic conductor composites through processing induced modifications of the grain boundary defect distribution.

Enhancing grain boundary ionic conductivity in mixed ionic–electronic conductors

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

Lin, Ye; Fang, Shumin; Su, Dong

Mixed ionic–electronic conductors are widely used in devices for energy conversion and storage. Grain boundaries in these materials have nanoscale spatial dimensions, which can generate substantial resistance to ionic transport due to dopant segregation. Here, we report the concept of targeted phase formation in a Ce 0.8Gd 0.2O 2₋δ–CoFe 2O 4 composite that serves to enhance the grain boundary ionic conductivity. Using transmission electron microscopy and spectroscopy approaches, we probe the grain boundary charge distribution and chemical environments altered by the phase reaction between the two constituents. The formation of an emergent phase successfully avoids segregation of the Gd dopantmore » and depletion of oxygen vacancies at the Ce 0.8Gd 0.2O 2₋δ–Ce 0.8Gd 0.2O 2₋δ grain boundary. This results in superior grain boundary ionic conductivity as demonstrated by the enhanced oxygen permeation flux. Lastly, this work illustrates the control of mesoscale level transport properties in mixed ionic–electronic conductor composites through processing induced modifications of the grain boundary defect distribution.« less

Glass composite waste forms for iodine confined in bismuth-embedded SBA-15

NASA Astrophysics Data System (ADS)

Yang, Jae Hwan; Park, Hwan Seo; Ahn, Do-Hee; Yim, Man-Sung

2016-11-01

The aim of this study was to stabilize bismuth-embedded SBA-15 that captured iodine gas by fabrication of monolithic waste forms. The iodine containing waste was mixed with Bi2O3 (a stabilizing additive) and low-temperature sintering glass followed by pelletizing and the sintering process to produce glass composite materials. Iodine volatility during the sintering process was significantly affected by the ratio of Bi2O3 and the glass composition. It was confirmed that BiI3, the main iodine phase within bismuth-embedded SBA-15, was effectively transformed to the mixed phases of Bi5O7I and BiOI. The initial leaching rates of iodine from the glass composite waste forms ranged 10-3-10-2 g/m2 day, showing the stability of the iodine phases encapsulated by the glassy networks. It was also observed that common groundwater anions (e.g., chloride, carbonate, sulfite, and fluoride) elevated the iodine leaching rate by anion exchange reactions. The present results suggest that the glass composite waste form of bismuth-embedded SBA-15 could be a candidate material for stable storage of 129I.

Experimental Study of Thermal Energy Storage Characteristics using Heat Pipe with Nano-Enhanced Phase Change Materials

NASA Astrophysics Data System (ADS)

Krishna, Jogi; Kishore, P. S.; Brusly Solomon, A.

2017-08-01

The paper presents experimental investigations to evaluate thermal performance of heat pipe using Nano Enhanced Phase Change Material (NEPCM) as an energy storage material (ESM) for electronic cooling applications. Water, Tricosane and nano enhanced Tricosane are used as energy storage materials, operating at different heating powers (13W, 18W and 23W) and fan speeds (3.4V and 5V) in the PCM cooling module. Three different volume percentages (0.5%, 1% and 2%) of Nano particles (Al2O3) are mixed with Tricosane which is the primary PCM. This experiment is conducted to study the temperature distributions of evaporator, condenser and PCM during the heating as well as cooling. The cooling module with heat pipe and nano enhanced Tricosane as energy storage material found to save higher fan power consumption compared to the cooling module that utilities only a heat pipe.

Ball-free mechanochemistry: in situ real-time monitoring of pharmaceutical co-crystal formation by resonant acoustic mixing.

PubMed

Michalchuk, Adam A L; Hope, Karl S; Kennedy, Stuart R; Blanco, Maria V; Boldyreva, Elena V; Pulham, Colin R

2018-04-17

Resonant acoustic mixing (RAM) is a new technology designed for intensive mixing of powders that offers the capability to process powders with minimal damage to particles. This feature is particularly important for mixing impact-sensitive materials such as explosives and propellants. While the RAM technique has been extensively employed for the mixing of powders and viscous polymers, comparatively little is known about its use for mechanosynthesis. We present here the first in situ study of RAM-induced co-crystallisation monitored using synchrotron X-ray powder diffraction. The phase profile of the reaction between nicotinamide and carbamazepine in the presence of a small amount of water was monitored at two different relative accelerations of the mixer. In marked contrast to ball-milling techniques, the lack of milling bodies in the RAM experiment does not hinder co-crystallisation of the two starting materials, which occurred readily and was independent of the frequency of oscillation. The reaction could be optimised by enhancing the number of reactive contacts through mixing and comminution. These observations provide new insight into the role of various experimental parameters in conventional mechanochemistry using liquid-assisted grinding techniques.

Controlling the surface‐mediated release of DNA using ‘mixed multilayers’

PubMed Central

Appadoo, Visham; Carter, Matthew C. D.

2016-01-01

Abstract We report the design of erodible ‘mixed multilayer’ coatings fabricated using plasmid DNA and combinations of both hydrolytically degradable and charge‐shifting cationic polymer building blocks. Films fabricated layer‐by‐layer using combinations of a model poly(β‐amino ester) (polymer 1) and a model charge‐shifting polymer (polymer 2) exhibited DNA release profiles that were substantially different than those assembled using DNA and either polymer 1 or polymer 2 alone. In addition, the order in which layers of these two cationic polymers were deposited during assembly had a profound impact on DNA release profiles when these materials were incubated in physiological buffer. Mixed multilayers ∼225 nm thick fabricated by depositing layers of polymer 1/DNA onto films composed of polymer 2/DNA released DNA into solution over ∼60 days, with multi‐phase release profiles intermediate to and exhibiting some general features of polymer 1/DNA or polymer 2/DNA films (e.g., a period of rapid release, followed by a more extended phase). In sharp contrast, ‘inverted’ mixed multilayers fabricated by depositing layers of polymer 2/DNA onto films composed of polymer 1/DNA exhibited release profiles that were almost completely linear over ∼60‐80 days. These and other results are consistent with substantial interdiffusion and commingling (or mixing) among the individual components of these compound materials. Our results reveal this mixing to lead to new, unanticipated, and useful release profiles and provide guidance for the design of polymer‐based coatings for the local, surface‐mediated delivery of DNA from the surfaces of topologically complex interventional devices, such as intravascular stents, with predictable long‐term release profiles. PMID:27981243

Synthesized Li4Ti5O12 from Technical Grade Raw Material by Excess LiOH.H2O as Anode Lithium Ion Battery

NASA Astrophysics Data System (ADS)

Priyono, S.; Primasari, R. D.; Saptari, S. A.; Prihandoko, B.

2017-07-01

Li4Ti5O12 powder as anode lithium ion battery was synthesized via solid state reaction with excess LiOH.H2O. Technical grades raw materials like LiOH.H2O and TiO2 were used as starting materials. LiOH.H2O excess was varied from 0; 2.5; 5 and 7.5% to get higher optimum phases and capacity of Li4Ti5O12. All raw materials were mixed stoichiometry then followed by calcination and sintering process to get final products. The obtained products were characterized by XRD, SEM, and PSA to get properties of active materials and the electrochemical properties were done by cyclic voltametry and charge-discharge test. The XRD test showed that 5% excess have highest Li4Ti5O12 phases. All samples have same in morphology, agglomerate and same in particle size distribution. Sample with 5% excess showed good reversible process and chargedischarge test showed that increasing Li4Ti5O12 phase can improve specific capacity.

Chocolate HILIC phases: development and characterization of novel saccharide-based stationary phases by applying non-enzymatic browning (Maillard reaction) on amino-modified silica surfaces.

PubMed

Schuster, Georg; Lindner, Wolfgang

2011-06-01

Novel saccharide-based stationary phases were developed by applying non-enzymatic browning (Maillard Reaction) on aminopropyl silica material. During this process, the reducing sugars glucose, lactose, maltose, and cellobiose served as "ligand primers". The reaction cascade using cellobiose resulted in an efficient chromatographic material which further served as our model Chocolate HILIC column. (Chocolate refers to the fact that these phases are brownish.) In this way, an amine backbone was introduced to facilitate convenient manipulation of selectivity by additional attractive or repulsive ionic solute-ligand interactions in addition to the typical HILIC retention mechanism. In total, six different test sets and five different mobile phase compositions were investigated, allowing a comprehensive evaluation of the new polar column. It became evident that, besides the so-called HILIC retention mechanism based on partition phenomena, additional adsorption mechanisms, including ionic interactions, take place. Thus, the new column is another example of a HILIC-type column characterized by mixed-modal retention increments. The glucose-modified materials exhibited the relative highest overall hydrophobicity of all grafted Chocolate HILIC columns which enabled retention of lipophilic analytes with high water content mobile phases.

Plasma Radiofrequency Discharges as Cleaning Technique for the Removal of C-W Coatings

NASA Astrophysics Data System (ADS)

Cremona, A.; Vassallo, E.; Caniello, R.; Ghezzi, F.; Grosso, G.; Laguardia, L.

2013-06-01

Erosion of materials by chemical and physical sputtering is one of the most concern of plasma wall interaction in tokamaks. In divertor ITER-like tokamaks, where carbon and tungsten are planned to be used, hydrogenated C-W mixed compounds are expected to form by erosion, transport and re-deposition processes. The selection of these materials as divertor components involves lifetime and safety issues due to tritium retention in carbon co-deposits. In this paper a cleaning technique based on RF (13.56 MHz) capacitively coupled H2/Ar plasmas has been used to remove C-W mixed materials from test specimens. The dependence of the removal rate on the H2/Ar ratio and on the plasma pressure has been investigated by X-ray photoelectron spectroscopy, atomic force microscopy, profilometry as regards the solid phase and by Langmuir probe and optical emission spectroscopy as regards the plasma phase. The best result has been obtained with a H2/Ar ratio of 10/90 at a pressure of 1 Pa. An explanation based on a synergistic effect between physical sputtering due to energetic ions and chemical etching due to radicals, together with the pressure dependence of the ion energy distribution function, is given.

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.

Photochemical route for accessing amorphous metal oxide materials for water oxidation catalysis.

PubMed

Smith, Rodney D L; Prévot, Mathieu S; Fagan, Randal D; Zhang, Zhipan; Sedach, Pavel A; Siu, Man Kit Jack; Trudel, Simon; Berlinguette, Curtis P

2013-04-05

Large-scale electrolysis of water for hydrogen generation requires better catalysts to lower the kinetic barriers associated with the oxygen evolution reaction (OER). Although most OER catalysts are based on crystalline mixed-metal oxides, high activities can also be achieved with amorphous phases. Methods for producing amorphous materials, however, are not typically amenable to mixed-metal compositions. We demonstrate that a low-temperature process, photochemical metal-organic deposition, can produce amorphous (mixed) metal oxide films for OER catalysis. The films contain a homogeneous distribution of metals with compositions that can be accurately controlled. The catalytic properties of amorphous iron oxide prepared with this technique are superior to those of hematite, whereas the catalytic properties of a-Fe(100-y-z)Co(y)Ni(z)O(x) are comparable to those of noble metal oxide catalysts currently used in commercial electrolyzers.

Microscopic origin of entropy-driven polymorphism in hybrid organic-inorganic perovskite materials

NASA Astrophysics Data System (ADS)

Butler, Keith T.; Svane, Katrine; Kieslich, Gregor; Cheetham, Anthony K.; Walsh, Aron

2016-11-01

Entropy is a critical, but often overlooked, factor in determining the relative stabilities of crystal phases. The importance of entropy is most pronounced in softer materials, where small changes in free energy can drive phase transitions, which has recently been demonstrated in the case of organic-inorganic hybrid-formate perovskites. In this Rapid Communication we demonstrate the interplay between composition and crystal structure that is responsible for the particularly pronounced role of entropy in determining polymorphism in hybrid organic-inorganic materials. Using ab initio based lattice dynamics, we probe the origins and effects of vibrational entropy of four archetype perovskite (A B X3 ) structures. We consider an inorganic material (SrTiO3), an A -site hybrid-halide material (CH3NH3) PbI3 , a X -site hybrid material KSr (BH4)3 , and a mixed A - and X -site hybrid-formate material (N2H5) Zn (HCO2)3 , comparing the differences in entropy between two common polymorphs. The results demonstrate the importance of low-frequency intermolecular modes in determining the phase stability in these materials. The understanding gained allows us to propose a general principle for the relative stability of different polymorphs of hybrid materials as temperature is increased.

Influence of sintering time on switching of the femtosecond nonlinear optical properties of CuNb2O6

NASA Astrophysics Data System (ADS)

Priyadarshani, N.; Sabari Girisun, T. C.; Venugopal Rao, S.

2017-04-01

Transition of mixed phases (monoclinic and orthorhombic) to pure orthorhombic phase was achieved during the synthesis process of CuNb2O6 by varying the sintering time. The suppression of monoclinic phase and dominant formation of orthorhombic CuNb2O6 was confirmed from the XRD and FTIR data analysis. FESEM studies demonstrated that due to increase in sintering time, coarsening process initiated the grain growth and trapping of pores leading to pore-free structures. The nonlinear optical (NLO) properties of mixed and pure copper niobate were studied by the Z-scan technique using near-infrared (800 nm, ∼150 fs, 80 MHz) laser excitation. Mixed phases exhibited saturable absorption and self-defocusing behaviour while pure orthorhombic demonstrated reverse saturable absorption and self-focusing process. The switching of nonlinearity along with increase in NLO coefficient of O-CuNb2O6 was attributed to the decreased metal-oxygen bond length and pore free structure. The increase in nonlinear absorption coefficient with input irradiance suggests the occurrence of effective 3 PA (2 PA followed by ESA) process. The magnitudes of nonlinear absorption coefficient (2.14 × 10-23m3/W2) and nonlinear refractive index (6.0 × 0-17 m2/W) of O-CuNb2O6 were found to be higher than well-known NLO materials. Orthorhombic CuNb2O6 exhibited optical limiting action with low limiting threshold of 38.26 μJ/cm2 and favouring NLO properties suggesting that the material to be an entrant candidate for safety devices against ultrashort pulsed lasers.

Specific Features of Profile Distribution and Crystallochemistry of Phyllosilicates in Soils of the Cisbaikal Forest-Steppe

NASA Astrophysics Data System (ADS)

Chizhikova, N. P.; Gamzikov, G. P.; Chechetko, E. S.

2018-01-01

The mineralogical composition of agrogray, dark gray, and agro-dark gray soils (Luvic Greyzemic Retic Phaeozems); agro-dark gray residual-calcareous soils (Calcaric Cambic Phaeozems); clay-illuvial agrochernozems (Luvic Chernic Phaeozems); and agrochernozems with migrational-mycelial carbonates (Haplic Chernozems) developed in the forest-steppe of Central Siberia within the Irkutsk Depression has been studied. The clay (<1 μm) fraction separated from these soils consists of mixed-layer minerals with alternating layers of hydromica, smectite, vermiculite, and chlorite; the proportions between them change within the soil profiles. The clay fraction also contains hydromicas, kaolinite, chlorite, and some admixture of the fine-dispersed quartz. Each type of the soils is characterized by its own distribution pattern of clay material with specific alternation of layers in the mixed-layer formations. Mixed-layer minerals of the chlorite-vermiculite type predominate in the upper horizons of texture-differentiated soils. Down the soil profile, the content of mixed-layer mica-smectitic minerals increases. In the clay fraction of arable dark gray-humus soils with residual carbonates, the distribution of the clay fraction and major mineral phases in the soil profile is relatively even. An increased content of well-crystallized kaolinite is typical of these soils. The parent material of agrochernozems has a layered character: the upper horizons are generally depleted of clay, and the middle-profile and lower horizons are characterized by the considerable kaolinite content. In general, the clay material of soils of the Tulun-Irkutsk forest-steppe differs considerably from the clay material of foreststeppe soils developed from loesslike and mantle loams in the European part of Russia. In particular, this difference is seen in the proportions between major mineral phases and between biotitic and muscovitic components, as well as in the degree of crystallinity and behavior of kaolinite and chlorite.

Quasi-phase-matched χ(3 )-parametric interactions in sinusoidally tapered waveguides

NASA Astrophysics Data System (ADS)

Saleh, Mohammed F.

2018-01-01

In this article, I show how periodically tapered waveguides can be employed as efficient quasi-phase-matching schemes for four-wave mixing parametric processes in third-order nonlinear materials. As an example, a thorough study of enhancing third-harmonic generation in sinusoidally tapered fibers has been conducted. The quasi-phase-matching condition has been obtained for nonlinear parametric interactions in these structures using Fourier-series analysis. The dependencies of the conversion efficiency of the third harmonic on the modulation amplitude, tapering period, longitudinal-propagation direction, and pump wavelength have been studied. In comparison to uniform waveguides, the conversion efficiency has been enhanced by orders of magnitudes. I envisage that this work will have a great impact in the field of guided nonlinear optics using centrosymmetric materials.

Mixing and electronic entropy contributions to thermal energy storage in low melting point alloys

NASA Astrophysics Data System (ADS)

Shamberger, Patrick J.; Mizuno, Yasushi; Talapatra, Anjana A.

2017-07-01

Melting of crystalline solids is associated with an increase in entropy due to an increase in configurational, rotational, and other degrees of freedom of a system. However, the magnitude of chemical mixing and electronic degrees of freedom, two significant contributions to the entropy of fusion, remain poorly constrained, even in simple 2 and 3 component systems. Here, we present experimentally measured entropies of fusion in the Sn-Pb-Bi and In-Sn-Bi ternary systems, and decouple mixing and electronic contributions. We demonstrate that electronic effects remain the dominant contribution to the entropy of fusion in multi-component post-transition metal and metalloid systems, and that excess entropy of mixing terms can be equal in magnitude to ideal mixing terms, causing regular solution approximations to be inadequate in the general case. Finally, we explore binary eutectic systems using mature thermodynamic databases, identifying eutectics containing at least one semiconducting intermetallic phase as promising candidates to exceed the entropy of fusion of monatomic endmembers, while simultaneously maintaining low melting points. These results have significant implications for engineering high-thermal conductivity metallic phase change materials to store thermal energy.

Fabrication of selective-area growth InGaN LED by mixed-source hydride vapor-phase epitaxy

NASA Astrophysics Data System (ADS)

Bae, Sung Geun; Jeon, Injun; Jeon, Hunsoo; Kim, Kyoung Hwa; Yang, Min; Yi, Sam Nyung; Lee, Jae Hak; Ahn, Hyung Soo; Yu, Young Moon; Sawaki, Nobuhiko; Kim, Suck-Whan

2018-01-01

We prepared InGaN light-emitting diodes (LEDs) with the active layers grown from a mixed source of Ga-In-N materials on an n-type GaN substrate by a selective-area growth method and three fabrication steps: photolithography, epitaxial layer growth, and metallization. The preparation followed a previously developed experimental process using apparatus for mixed-source hydride vapor-phase epitaxy (HVPE), which consisted of a multi-graphite boat, for insulating against the high temperature and to control the growth rate of epilayers, filled with the mixed source on the inside and a radio-frequency (RF) heating coil for heating to a high temperature (T > 900 °C) and for easy control of temperature outside the source zone. Two types of LEDs were prepared, with In compositions of 11.0 and 6.0% in the InGaN active layer, and room-temperature electroluminescence measurements exhibited a main peak corresponding to the In composition at either 420 or 390 nm. The consecutive growth of InGaN LEDs by the mixed-source HVPE method provides a technique for the production of LEDs with a wide range of In compositions in the active layer.

Quantify the energy and environmental effects of using recycled asphalt and recycled concrete for pavement construction phase I : final report.

DOT National Transportation Integrated Search

2009-08-01

The objective of this study is to quantify the energy and environment impacts from using recycled materials : for highway construction. Specifically, when recycled asphalt pavement is re-used for producing hot mix : asphalt or when recycled concrete ...

Role of precursor crystal structure on electrochemical performance of carbide-derived carbon electrodes

NASA Astrophysics Data System (ADS)

Palazzo, Benjamin; Norris, Zach; Taylor, Greg; Yu, Lei; Lofland, Samuel; Hettinger, Jeffrey

2015-03-01

Binary carbides with hexagonal and cubic crystal structures have been synthesized by reactive magnetron sputtering of vanadium and other transition metals in acetylene or methane gas mixed with argon. The binary carbides are converted to carbide-derived carbon (CDC) films using chlorine gas in a post-deposition process in an external vacuum reaction furnace. Residual chlorine has been removed using an annealing step in a hydrogen atmosphere. The CDC materials have been characterized by x-ray diffraction, x-ray fluorescence, and scanning electron microscopy. The performance of the CDC materials in electrochemical device applications has been measured with the hexagonal phase precursor demonstrating a significantly higher specific capacitance in comparison to that of the cubic phase. We report these results and pore-size distributions of these and similar materials.

Amorphous Silk Fibroin Membranes for Separation of CO2

NASA Technical Reports Server (NTRS)

Aberg, Christopher M.; Patel, Anand K.; Gil, Eun Seok; Spontak, Richard J.; Hagg, May-Britt

2009-01-01

Amorphous silk fibroin has shown promise as a polymeric material derivable from natural sources for making membranes for use in removing CO2 from mixed-gas streams. For most applications of silk fibroin, for purposes other than gas separation, this material is used in its highly crystalline, nearly natural form because this form has uncommonly high tensile strength. However, the crystalline phase of silk fibroin is impermeable, making it necessary to convert the material to amorphous form to obtain the high permeability needed for gas separation. Accordingly, one aspect of the present development is a process for generating amorphous silk fibroin by treating native silk fibroin in an aqueous methanol/salt solution. The resulting material remains self-standing and can be prepared as thin film suitable for permeation testing. The permeability of this material by pure CO2 has been found to be highly improved, and its mixed-gas permeability has been found to exceed the mixed-gas permeabilities of several ultrahigh-CO2-permeable synthetic polymers. Only one of the synthetic polymers poly(trimethylsilylpropyne) [PTMSP] may be more highly permeable by CO2. PTMSP becomes unstable with time, whereas amorphous silk should not, although at the time of this reporting this has not been conclusively proven.

Mixed phase clouds: observations and theoretical advances (overview)

NASA Astrophysics Data System (ADS)

Korolev, Alexei

2013-04-01

Mixed phase clouds play important role in precipitation formation and radiation budget of the Earth. The microphysical measurements in mixed phase clouds are notoriously difficult due to many technical challenges. The airborne instrumentation for characterization of the microstructure of mixed phase clouds is discussed. The results multiyear airborne observations and measurements of frequency of occurrence of mixed phase, characteristic spatial scales, humidity in mixed phase and ice clouds are presented. A theoretical framework describing the thermodynamics and phase transformation of a three phase component system consisting of ice particles, liquid droplets and water vapor is discussed. It is shown that the Wegener-Bergeron-Findeisen process plays different role in clouds with different dynamics. The problem of maintenance and longevity of mixed phase clouds is discussed.

Different Device Architectures for Bulk-Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Adam, Getachew; Munkhbat, Battulga; Denk, Patrick; Ulbricht, Christoph; Hrelescu, Calin; Scharber, Markus

2016-08-01

Titania is the most widely studied photocatalyst. In it’s mixed-phase configuration (anatase-rutile form) -as manifested in the commercially available P25 Degussa material- titania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field have not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypothesis in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or “catalytic “hot-spots””. Therefore, non-woven nanofibrous mats of titania were produced and upon calcination the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500˚C with an anatase /rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

Optimized nanostructured TiO2 photocatalysts

NASA Astrophysics Data System (ADS)

Topcu, Selda; Jodhani, Gagan; Gouma, Pelagia

2016-07-01

Titania is the most widely studied photocatalyst. In it’s mixed-phase configuration (anatase-rutile form) -as manifested in the commercially available P25 Degussa material- titania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field have not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypothesis in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or “catalytic “hot-spots””. Therefore, non-woven nanofibrous mats of titania were produced and upon calcination the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500˚C with an anatase /rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

High-temperature thermochemical energy storage based on redox reactions using Co-Fe and Mn-Fe mixed metal oxides

NASA Astrophysics Data System (ADS)

André, Laurie; Abanades, Stéphane; Cassayre, Laurent

2017-09-01

Metal oxides are potential materials for thermochemical heat storage via reversible endothermal/exothermal redox reactions, and among them, cobalt oxide and manganese oxide are attracting attention. The synthesis of mixed oxides is considered as a way to answer the drawbacks of pure metal oxides, such as slow reaction kinetics, loss-in-capacity over cycles or sintering issues, and the materials potential for thermochemical heat storage application needs to be assessed. This work proposes a study combining thermodynamic calculations and experimental measurements by simultaneous thermogravimetric analysis and calorimetry, in order to identify the impact of iron oxide addition to Co and Mn-based oxides. Fe addition decreased the redox activity and energy storage capacity of Co3O4/CoO, whereas the reaction rate, reversibility and cycling stability of Mn2O3/Mn3O4 was significantly enhanced with added Fe amounts above 15 mol%, and the energy storage capacity was slightly improved. The formation of a reactive cubic spinel explained the improved re-oxidation yield of Mn-based oxides that could be cycled between bixbyite and cubic spinel phases, whereas a low reactive tetragonal spinel phase showing poor re-oxidation was formed below 15 mol% Fe. Thermodynamic equilibrium calculations predict accurately the behavior of both systems. The possibility to identify other suitable mixed oxides becomes conceivable, by enabling the selection of transition metal additives for tuning the redox properties of mixed metal oxides destined for thermochemical energy storage applications.

Transition-Metal Mixing and Redox Potentials in Li x (M 1–y M' y )PO 4 (M, M' = Mn, Fe, Ni) Olivine Materials from First-Principles Calculations

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

Snydacker, David H.; Wolverton, Chris

The performance of olivine cathode materials can be improved using core/shell structures such as LiMnPO 4/LiFePO 4 and LiMnPO 4/LiNiPO 4. We use density functional theory to calculate the energetics, phase stability, and voltages of transition-metal mixing for a series of olivine phosphate materials. For LiMn 1–yFe yPO 4, LiFe 1–yNi yPO 4, and LiMn 1–yNi yPO 4, we find phase-separating tendencies with (mean-field) maximum miscibility gap temperatures of 120, 320, and 760 K respectively. At room temperature, we find that Mn is completely miscible in LiFePO 4, whereas Mn solubility in LiNiPO 4 is just 0.3%. Therefore, we suggestmore » that core/shell LiMnPO 4/LiNiPO 4 particles could be more effective at containing Mn in the particle core and limiting Mn dissolution into the electrolyte relative to LiMnPO 4/LiFePO 4 particles. We calculate shifts in redox potentials for dilute transition metals, M, substituted into Li xM'PO 4 host materials. Unmixed Li xMnPO 4 exhibits a redox potential of 4.0 V, but we find that dilute Mn in a LiNiPO 4 shell exhibits a redox potential of 4.3 V and therefore remains redox inactive at lower cathode potentials. We find that strain plays a large role in the redox potentials of some mixed systems (Li xMn 1–yFe yPO 4) but not others (Li xMn 1–yNi yPO 4).« less

Barium Stars and Thermohaline Mixing

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

Husti, Laura

2008-01-24

Barium stars are formed in binary systems through mass transfer from the carbon and s-element rich primary in the AGB phase, to the secondary star which is in a less evolved evolutionary stage. The mixing of the accreted material from the AGB donor with the envelope of the secondary results in a dilution of the s-element abundances. Dilution in red giants is explained by the occurence of the first dredge up, while in case of dwarfs thermohaline mixing would determine it. A comparison between the theoretical predictions of the AGB stellar models and the spectroscopical observations of a large samplemore » of barium stars has been made. Dilution due to thermohaline mixing was taken into account when searching for best fits of the observational data. The importance of thermohaline mixing in barium dwarfs is discussed.« less

Synthesis-Free Phase-Selective Gelator for Oil-Spill Remediation.

PubMed

Cui, Yaowen; Li, Mei-Chun; Wu, Qinglin; Pojman, John A; Kuroda, Daniel G

2017-10-04

A new deep eutectic solvent (DES) was developed as a phase-selective gelator for oil-spill remediation. The newly designed nonionic DES is based on a combination of an amide (N-methylacetamide) and a long chain carboxylic acid (lauric acid) and does not require any synthetic procedure besides mixing. Our studies show that the DES works as gelator by forming a gel between lauric acid and the hydrocarbon, whereas the amide serves to form the DES and dissolves in water during the gelation process. In addition, the DES material has gelation properties comparable to those considered as state-of-the-art. Overall, the newly developed material shows a promising future in oil recovery methodologies.

Thermodynamics of Titanium-Aluminum-Oxygen Alloys Studied

NASA Technical Reports Server (NTRS)

Copland, Evan H.; Jacobson, Nathan S.

2001-01-01

Titanium-aluminum alloys are promising intermediate-temperature alloys for possible compressor applications in gas-turbine engines. These materials are based on the a2-Ti3Al + g-TiAl phases. The major issue with these materials is high oxygen solubility in a2-Ti3Al, and oxidation of unsaturated alloys generally leads to mixed non-protective TiO2+Al2O3 scales. From phase diagram studies, oxygen saturated a2-Ti3Al(O) is in equilibrium with Al2O3; however, oxygen dissolution has a detrimental effect on mechanical properties and cannot be accepted. To better understand the effect of oxygen dissolution, we examined the thermodynamics of titanium-aluminum-oxygen alloys.

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

Abdelaziz, Omar; Mallow, Anne; Graham, Samuel

Organic materials, such as paraffin wax, are sought as stable and environmentally friendly phase change materials (PCM) for thermal energy storage, but they suffer from low thermal conductivity which limits the rate at which thermal energy flows into and out of the material. A common method to improve the PCM thermal behavior is through loading with high thermal conductivity particulate fillers. However, the stability of these composites in the molten state is a concern as settling of the fillers will change the effective thermal conductivity. In this work, we investigate the stability of wax loaded with exfoliated graphite nanoplatelets eithermore » of 1 m (xGnP-1) or 15 m (xGnP-15) diameter. The effect of dispersants, oxidation of the wax, viscosity of the wax, mixing time, and hydrocarbon chain length on stability is reported. It was found that the addition of octadecylphosphonic acid (ODPA) is an effective dispersant for xGnP in paraffin and microcrystalline wax. In addition, mixing time, viscosity, and oxidation of the wax influence stability in the molten state. Overall, it was found that a mixing time of 24 hours for xGnP-15 along with ODPA mixed in a high viscosity, oxidized microcrystalline wax results in composite PCM systems with the greatest stability determined at 80 C in the molten state.« less

Synthesis and Characterization of Some Alkaline-Earth-Oxide Nanoparticles

NASA Astrophysics Data System (ADS)

Singh, Jitendra Pal; Lim, Weon Cheol; Won, Sung Ok; Song, Jonghan; Chae, Keun Hwa

2018-04-01

The present work reports the synthesis of MgO and CaO nanoparticles by using the sol-gel autocombustion method. The annealing of the precursor at 1200 °C was observed to lead the formation of MgO nanoparticles having average crystallite size of 31 nm. Annealing the precursor at same temperature produced materials having a CaO phase with a minor impure phase of calcium carbonate ( 3%). The crystallite size corresponding to the CaO phase was 38 nm. A change of thermal history in the precursor was observed not to result in an improvement of the CaO phase. The change of thermal history in the precursor gave rise to mixed phases of CaCO3 and Ca(OH)2 rather than the phase of CaO. Further, annealing at 1200 °C for 12 h resulted in the formation of the CaO phase along with almost 1 - 5% of calcium hydroxide as an impurity phase. X-ray absorption spectroscopic measurements carried out on these materials revealed that the local electronic/atomic structure of these oxides was not only affected by the impurity phases but also influenced by the carbaneous impurities attached to the crystallites.

A major advance in powder metallurgy

NASA Technical Reports Server (NTRS)

Williams, Brian E.; Stiglich, Jacob J., Jr.; Kaplan, Richard B.; Tuffias, Robert H.

1991-01-01

Ultramet has developed a process which promises to significantly increase the mechanical properties of powder metallurgy (PM) parts. Current PM technology uses mixed powders of various constituents prior to compaction. The homogeneity and flaw distribution in PM parts depends on the uniformity of mixing and the maintenance of uniformity during compaction. Conventional PM fabrication processes typically result in non-uniform distribution of the matrix, flaw generation due to particle-particle contact when one of the constituents is a brittle material, and grain growth caused by high temperature, long duration compaction processes. Additionally, a significant amount of matrix material is usually necessary to fill voids and create 100 percent dense parts. In Ultramet's process, each individual particle is coated with the matrix material, and compaction is performed by solid state processing. In this program, Ultramet coated 12-micron tungsten particles with approximately 5 wt percent nickel/iron. After compaction, flexure strengths were measured 50 percent higher than those achieved in conventional liquid phase sintered parts (10 wt percent Ni/Fe). Further results and other material combinations are discussed.

Determination of Young's modulus of epoxy coated polyethylene micro-cantilever using phase-shift shadow moiré method

NASA Astrophysics Data System (ADS)

Lim, J. H.; Ratnam, M. M.; Azid, I. A.; Mutharasu, D.

2011-11-01

Young's moduli of various epoxy coated polyethylene terephthalate (PET) micro-cantilevers were determined from the deflection results obtained using the phase-shift shadow moiré (PSSM) method. The filler materials for epoxy coatings were aluminum and graphite powders that were mixed with epoxy at various percentages. Young's moduli were calculated from theory based on the deflection results. The PET micro-cantilever coated with aluminum-epoxy coating showed increasing value of Young's modulus when the ratios of the aluminum-epoxy were increased. The graphite-epoxy coating on the PET micro-cantilever also showed the same trend. The experimental results also show that Young's modulus of the graphite-epoxy coating is higher than aluminum-epoxy coating in comparison at the same mixing ratio.

Effect of lattice-mismatch-induced strains on coupled diffusive and displacive phase transformations

NASA Astrophysics Data System (ADS)

Bouville, Mathieu; Ahluwalia, Rajeev

2007-02-01

Materials which can undergo slow diffusive transformations as well as fast displacive transformations are studied using the phase-field method. The model captures the essential features of the time-temperature-transformation (TTT) diagrams, continuous cooling transformation (CCT) diagrams, and microstructure formation of these alloys. In some material systems there can exist an intrinsic volume change associated with these transformations. We show that these coherency strains can stabilize mixed microstructures (such as retained austenite-martensite and pearlite-martensite mixtures) by an interplay between diffusive and displacive mechanisms, which can alter TTT and CCT diagrams. Depending on the conditions there can be competitive or cooperative nucleation of the two kinds of phases. The model also shows that small differences in volume changes can have noticeable effects on the early stages of martensite formation and on the resulting microstructures.

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition

NASA Astrophysics Data System (ADS)

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-01

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

Ag-Cu mixed phase plasmonic nanostructures fabricated by shadow nanosphere lithography and glancing angle co-deposition.

PubMed

Ingram, Whitney; Larson, Steven; Carlson, Daniel; Zhao, Yiping

2017-01-06

By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory. All compositions of the nanopattern had the same shape, but showed tunable localized surface plasmon resonance (LSPR) properties. In general, the LSPR of the nanopatterns redshifted with decreasing composition. Such a relation could be fitted by an empirical model based on the bulk theory of alloy plasmonics. By changing the colloidal template and the material deposited, this fabrication technique can be used to produce other alloy plasmonic nanostructures with predicted LSPR wavelengths.

A mixed-penalty biphasic finite element formulation incorporating viscous fluids and material interfaces.

PubMed

Chan, B; Donzelli, P S; Spilker, R L

2000-06-01

The fluid viscosity term of the fluid phase constitutive equation and the interface boundary conditions between biphasic, solid and fluid domains have been incorporated into a mixed-penalty finite element formulation of the linear biphasic theory for hydrated soft tissue. The finite element code can now model a single-phase viscous incompressible fluid, or a single-phase elastic solid, as limiting cases of a biphasic material. Interface boundary conditions allow the solution of problems involving combinations of biphasic, fluid and solid regions. To incorporate these conditions, the volume-weighted mixture velocity is introduced as a degree of freedom at interface nodes so that the kinematic continuity conditions are satisfied by conventional finite element assembly techniques. Results comparing our numerical method with an independent, analytic solution for the problem of Couette flow over rigid and deformable porous biphasic layers show that the finite element code accurately predicts the viscous fluid flows and deformation in the porous biphasic region. Thus, the analysis can be used to model the interface between synovial fluid and articular cartilage in diarthrodial joints. This is an important step toward modeling and understanding the mechanisms of joint lubrication and another step toward fully modeling the in vivo behavior of a diarthrodial joint.

Method for the production of ultrafine particles by electrohydrodynamic micromixing

DOEpatents

DePaoli, David W.; Hu, Zhong Cheng; Tsouris, Constantinos

2001-01-01

The present invention relates to a method for the rapid production of homogeneous, ultrafine inorganic material via liquid-phase reactions. The method of the present invention employs electrohydrodynamic flows in the vicinity of an electrified injector tube placed inside another tube to induce efficient turbulent mixing of two fluids containing reactive species. The rapid micromixing allows liquid-phase reactions to be conducted uniformly at high rates. This approach allows continuous production of non-agglomerated, monopispersed, submicron-sized, sphere-like powders.

A high yield reverse micelle synthesis of catalysts and catalyst precursors

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

Linehan, J.C.; Matson, D.W.; Darab, J.G.

1995-04-01

Reverse micelles or water-in-oil microemulsions have been prepared using a mixed AOT/SDS surfactant to increase the stability of the microemulsion and thereby allow a high loading of particle-forming precursors in the aqueous cores. The Modified Reverse Micelles (MRM), as these new binary surfactant microemulsions are called, have proven useful for the laboratory-scale synthesis of nanoscale metals, metal oxides, metal sulfides, and mixed metal materials. The system allows control over the phase and size of the precipitated crystallites and is ideal for producing nanocrystalline powders and suspensions.

Development of quality standards for inclusion of high recycled asphalt pavement content in asphalt mixtures - phase II, [tech brief].

DOT National Transportation Integrated Search

2015-03-01

The objective of this research is to 1) build a test section utilizing HMA : mix designs with up to 40% RAP materials, 2) evaluate the moisture : sensitivity of High-RAP mixtures, 3) characterize the low-temperature : fracture behavior of High-RAP mi...

Mobile, stationary and mixed phase tracers: consequences to sea ice biogeochemistry

NASA Astrophysics Data System (ADS)

Jeffery, N.; Elliott, S.; Hunke, E. C.; Deal, C.; Jin, M.

2016-02-01

Models of brine motion in sea ice have offered mechanisms for transporting biogeochemical compounds vertically within the ice and between the ice-ocean interface. In these models, sea ice microstructure and/or gross physical properties determine the resupply of nitrate, for example, to sympagic algae and that resupply, in large part, constrains sea ice primary production. The assumption of brine transport models is that the transported matter exists in a purely mobile phase within the ice brine channels. As a result, non-reacting, mobile phase tracers evolve like salinity in dynamic sea ice. Field and laboratory observations indicate that this is a good approximation for the primary algal macronutrients - nitrate, silicate and phosphate, but clear deviations are evident for ammonium, micronutrients such as iron, humic substances, algal bi-products such as gels and extracellular polysaccharides, and the algae themselves. This wide range of biogeochemical matter resists brine motion and is present in both the mobile and stationary phases, i.e. these tracers are "mixed" with respect to their transport phases. Although the precise mechanism for this resistance may be due to attachment by frustules, "stickiness" of the material surface, adsorption, or, in the case of microorganisms, active motility, a key common element in all cases is the presence of the ice matrix. In this presentation we investigate the consequences of mixed phase tracers in sea ice on algal concentrations, vertical distributions, and the potential accumulation of biogeochemical matter within the ice. We assume that sea ice growth promotes retention to the stationary phase, while melt and the disintegration of the ice matrix promotes release into the mobile phase. By varying the retention and release timescales of this formulation, we retrieve the purely mobile and maximal accumulation limits.

Additive Construction with Mobile Emplacement (ACME) / Automated Construction of Expeditionary Structures (ACES) Materials Delivery System (MDS)

NASA Technical Reports Server (NTRS)

Mueller, R. P.; Townsend, I. I.; Tamasy, G. J.; Evers, C. J.; Sibille, L. J.; Edmunson, J. E.; Fiske, M. R.; Fikes, J. C.; Case, M.

2018-01-01

The purpose of the Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) project is to incorporate the Liquid Goods Delivery System (LGDS) into the Dry Goods Delivery System (DGDS) structure to create an integrated and automated Materials Delivery System (MDS) for 3D printing structures with ordinary Portland cement (OPC) concrete. ACES 3 is a prototype for 3-D printing barracks for soldiers in forward bases, here on Earth. The LGDS supports ACES 3 by storing liquid materials, mixing recipe batches of liquid materials, and working with the Dry Goods Feed System (DGFS) previously developed for ACES 2, combining the materials that are eventually extruded out of the print nozzle. Automated Construction of Expeditionary Structures, Phase 3 (ACES 3) is a project led by the US Army Corps of Engineers (USACE) and supported by NASA. The equivalent 3D printing system for construction in space is designated Additive Construction with Mobile Emplacement (ACME) by NASA.

A New Multiphase Equation of State for SiO 2

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

Maerzke, Katie A.; Gammel, J. Tinka

SiO 2 is found as α-quartz at ambient conditions. Under shock compression, it transforms into a much higher density stishovite-like phase around 20 GPa, then into a liquid phase above 100 GPa. The SESAME library contains older equations of state for α-quartz, polycrystalline quartz, and fused quartz. These equations of state model the material as a single phase; i.e., there is no high pressure phase transition. Somewhat more recently (in 1992), Jon Boettger published equations of state for α-quartz, coesite, and stishovite, along with a phase transition model to mix them. However, we do not have a multiphase EOS thatmore » captures the phase transitions in this material. Others are working on a high-accuracy model for very high pressure SiO 2, since liquid quartz is used as an impedance matching standard above 100 GPa; however, we are focused on the 10-50 GPa range. This intermediate pressure range is most relevant for modeling the decomposition products of silicone polymers such as Sylgard 184 and SX358.« less

Twinned Growth of Metal-Free, Triazine-Based Photocatalyst Films as Mixed-Dimensional (2D/3D) van der Waals Heterostructures.

PubMed

Schwarz, Dana; Noda, Yu; Klouda, Jan; Schwarzová-Pecková, Karolina; Tarábek, Ján; Rybáček, Jiří; Janoušek, Jiří; Simon, Frank; Opanasenko, Maksym V; Čejka, Jiří; Acharjya, Amitava; Schmidt, Johannes; Selve, Sören; Reiter-Scherer, Valentin; Severin, Nikolai; Rabe, Jürgen P; Ecorchard, Petra; He, Junjie; Polozij, Miroslav; Nachtigall, Petr; Bojdys, Michael J

2017-10-01

Design and synthesis of ordered, metal-free layered materials is intrinsically difficult due to the limitations of vapor deposition processes that are used in their making. Mixed-dimensional (2D/3D) metal-free van der Waals (vdW) heterostructures based on triazine (C 3 N 3 ) linkers grow as large area, transparent yellow-orange membranes on copper surfaces from solution. The membranes have an indirect band gap (E g,opt = 1.91 eV, E g,elec = 1.84 eV) and are moderately porous (124 m 2 g -1 ). The material consists of a crystalline 2D phase that is fully sp 2 hybridized and provides structural stability, and an amorphous, porous phase with mixed sp 2 -sp hybridization. Interestingly, this 2D/3D vdW heterostructure grows in a twinned mechanism from a one-pot reaction mixture: unprecedented for metal-free frameworks and a direct consequence of on-catalyst synthesis. Thanks to the efficient type I heterojunction, electron transfer processes are fundamentally improved and hence, the material is capable of metal-free, light-induced hydrogen evolution from water without the need for a noble metal cocatalyst (34 µmol h -1 g -1 without Pt). The results highlight that twinned growth mechanisms are observed in the realm of "wet" chemistry, and that they can be used to fabricate otherwise challenging 2D/3D vdW heterostructures with composite properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tailor Made Synthesis of T-Shaped and π-STACKED Dimers in the Gas Phase: Concept for Efficient Drug Design and Material Synthesis

NASA Astrophysics Data System (ADS)

Kumar, Sumit; Das, Aloke

2013-06-01

Non-covalent interactions play a key role in governing the specific functional structures of biomolecules as well as materials. Thus molecular level understanding of these intermolecular interactions can help in efficient drug design and material synthesis. It has been found from X-ray crystallography that pure hydrocarbon solids (i.e. benzene, hexaflurobenzene) have mostly slanted T-shaped (herringbone) packing arrangement whereas mixed solid hydrocarbon crystals (i.e. solid formed from mixtures of benzene and hexafluorobenzene) exhibit preferentially parallel displaced (PD) π-stacked arrangement. Gas phase spectroscopy of the dimeric complexes of the building blocks of solid pure benzene and mixed benzene-hexafluorobenzene adducts exhibit similar structural motifs observed in the corresponding crystal strcutures. In this talk, I will discuss about the jet-cooled dimeric complexes of indole with hexafluorobenzene and p-xylene in the gas phase using Resonant two photon ionzation and IR-UV double resonance spectroscopy combined with quantum chemistry calculations. In stead of studying benzene...p-xylene and benzene...hexafluorobenzene dimers, we have studied corresponding indole complexes because N-H group is much more sensitive IR probe compared to C-H group. We have observed that indole...hexafluorobenzene dimer has parallel displaced (PD) π-stacked structure whereas indole...p-xylene has slanted T-shaped structure. We have shown here selective switching of dimeric structure from T-shaped to π-stacked by changing the substituent from electron donating (-CH3) to electron withdrawing group (fluorine) in one of the complexing partners. Thus, our results demonstrate that efficient engineering of the non-covalent interactions can lead to efficient drug design and material synthesis.

The environmental footprint of a membrane bioreactor treatment process through Life Cycle Analysis.

PubMed

Ioannou-Ttofa, L; Foteinis, S; Chatzisymeon, E; Fatta-Kassinos, D

2016-10-15

This study includes an environmental analysis of a membrane bioreactor (MBR), the objective being to quantitatively define the inventory of the resources consumed and estimate the emissions produced during its construction, operation and end-of-life deconstruction. The environmental analysis was done by the life cycle assessment (LCA) methodology, in order to establish with a broad perspective and in a rigorous and objective way the environmental footprint and the main environmental hotspots of the examined technology. Raw materials, equipment, transportation, energy use, as well as air- and waterborne emissions were quantified using as a functional unit, 1m(3) of urban wastewater. SimaPro 8.0.3.14 was used as the LCA analysis tool, and two impact assessment methods, i.e. IPCC 2013 version 1.00 and ReCiPe version 1.10, were employed. The main environmental hotspots of the MBR pilot unit were identified to be the following: (i) the energy demand, which is by far the most crucial parameter that affects the sustainability of the whole process, and (ii) the material of the membrane units. Overall, the MBR technology was found to be a sustainable solution for urban wastewater treatment, with the construction phase having a minimal environmental impact, compared to the operational phase. Moreover, several alternative scenarios and areas of potential improvement, such as the diversification of the electricity mix and the material of the membrane units, were examined, in order to minimize as much as possible the overall environmental footprint of this MBR system. It was shown that the energy mix can significantly affect the overall sustainability of the MBR pilot unit (i.e. up to 95% reduction of the total greenhouse gas emissions was achieved with the use of an environmentally friendly energy mix), and the contribution of the construction and operational phase to the overall environmental footprint of the system. Copyright © 2016 Elsevier B.V. All rights reserved.

STS-42 Phase Partitioning Experiment (PPE) closeup taken onboard OV-103

NASA Technical Reports Server (NTRS)

1992-01-01

STS-42 Phase Partitioning Experiment (PPE), an International Microgravity Laboratory 1 (IML-1) experiment, is documented in a closeup taken onboard Discovery, Orbiter Vehicle (OV) 103. Phase partitioning is a very effective technique used by biochemists and cell biologists to obtain fairly pure cells. Cells are separated and collected in a mixture of two immiscible liquids (fluids that tend not to mix) by their surface characteristics. In the PPE, investigators feel they will be able to separate closely related cells because cell density and convection flows are not factors in the phase partitioning process in space. They also hope to study other factors that influence the process. Phase partitioning is used to separate biological materials such as bone marrow cells for cancer treatment.

Conducting nanotubes or nanostructures based composites, method of making them and applications

NASA Technical Reports Server (NTRS)

Gupta, Mool C. (Inventor); Yang, Yonglai (Inventor); Dudley, Kenneth L. (Inventor); Lawrence, Roland W. (Inventor)

2013-01-01

An electromagnetic interference (EMI) shielding material includes a matrix of a dielectric or partially conducting polymer, such as foamed polystyrene, with carbon nanotubes or other nanostructures dispersed therein in sufficient concentration to make the material electrically conducting. The composite is formed by dispersing the nanotube material in a solvent in which the dielectric or partially conducting polymer is soluble and mixing the resulting suspension with the dielectric or partially conducting polymer. A foaming agent can be added to produce a lightweight foamed material. An organometallic compound can be added to enhance the conductivity further by decomposition into a metal phase.

Probing the Evaporation Dynamics of Mixed SOA/Squalane Particles Using Size-Resolved Composition and Single-Particle Measurements.

PubMed

Robinson, Ellis Shipley; Saleh, Rawad; Donahue, Neil M

2015-08-18

An analysis of the formation and evaporation of mixed-particles containing squalane (a surrogate for hydrophobic primary organic aerosol, POA) and secondary organic aerosol (SOA) is presented. In these experiments, one material (D62-squalane or SOA from α-pinene + O3) was prepared first to serve as surface area for condensation of the other, forming the mixed-particles. The mixed-particles were then subjected to a heating-ramp from 22 to 44 °C. We were able to determine that (1) almost all of the SOA mass is comprised of material less volatile than D62-squalane; (2) AMS collection efficiency in these mixed-particle systems can be parametrized as a function of the relative mass fraction of the components; and (3) the vast majority of D62-squalane is able to evaporate from the mixed particles, and does so on the same time scale regardless of the order of preparation. We also performed two-population mixing experiments to directly test whether D62-squalane and SOA from α-pinene + O3 form a single solution or two separate phases. We find that these two OA types are immiscible, which informs our inference of the morphology of the mixed-particles. If the morphology is core-shell and dictated by the order of preparation, these data indicate that squalane is able to diffuse relatively quickly through the SOA shell, implying that there are no major diffusion limitations.

Ceramic-glass-metal seal by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1985-01-01

A method for producing a ceramic-glass-metal seal by microwaving mixes a slurry of glass sealing material and coupling agent and applies same to ceramic and metal workpieces. The slurry and workpieces are then insulated and microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by diffusion rather than by wetting of the reactants.

Ceramic-glass-metal seal by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1983-10-04

A method for producing a ceramic-glass-metal seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic and metal workpieces. The slurry and workpieces are then insulated and microwaved at a power, time and frequency sufficient to cause a liquid-phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by diffusion rather than by wetting of the reactants.

The effect of BaM/PANI composition with epoxy paint matrix on single and double layers coating with spray coating method for radar absorbing materials applications

NASA Astrophysics Data System (ADS)

Widyastuti, Fajarin, Rindang; Pratiwi, Vania Mitha; Kholid, Rifki Rachman; Habib, Abdulloh

2018-04-01

In this study, RAM composite has been succesfully synthesized by mixing BaM as magnetic materials and PANI as conductive materials. BaM and PANI materials were prepared separately by solid state method and polymerization method, respectively. To investigated the presence of BaM phase and magnetic property of the as prepared BaM, XRD pert PAN analytical and VSM 250 Dexing Magnet were employed. Inductance Capacitance Resistance technique was carried out to measure electrical conductivity of the synthesized PANI materials. In order to further characterized the structural features of BaM and PANI, SEM-EDX FEI 850 and FTIR characterizations were conducted. RAM composite was prepared by mixing BaM and PANI powders with ultrasonic cleaner. Afterwards, VNA (Vector Network Analyzer) characterization was carried out to determine reflection loss value of RAM by applying mixed RAM composite and epoxy paint on aluminum plate using spray gun. Microscopic characterization was employed to investigated the distribution of RAM particles on the substrate. It was found that reflection loss value as low as -27.153 dB was achieved when applied 15 wt% BaM/PANi composite at 100.6 µm thickness. In addition, the absorption of electromagnetic waves value increase as the addition of RAM composite composition increases.

Preparation of Al/Fe-Pillared Clays: Effect of the Starting Mineral

PubMed Central

Muñoz, Helir-Joseph; Blanco, Carolina; Galeano, Luis-Alejandro

2017-01-01

Four natural clays were modified with mixed polyoxocations of Al/Fe for evaluating the effect of the physicochemical properties of the starting materials (chemical composition, abundance of expandable clay phases, cationic exchange capacity and textural properties) on final physicochemical and catalytic properties of Al/Fe-PILCs. The aluminosilicate denoted C2 exhibited the highest potential as starting material in the preparation of Al/Fe-PILC catalysts, mainly due to its starting cationic exchange capacity (192 meq/100 g) and the dioctahedral nature of the smectite phase. These characteristics favored the intercalation of the mixed (Al13−x/Fex)7+ Keggin-type polyoxocations, stabilizing a basal spacing of 17.4 Å and high increase of the BET surface (194 m2/g), mainly represented in microporous content. According to H2-TPR analyses, catalytic performance of the incorporated Fe in the Catalytic Wet Peroxide Oxidation (CWPO) reaction strongly depends on the level of location in mixed Al/Fe pillars. Altogether, such physicochemical characteristics promoted high performance in CWPO catalytic degradation of methyl orange in aqueous medium at very mild reaction temperatures (25.0 ± 1.0 °C) and pressure (76 kPa), achieving TOC removal of 52% and 70% of azo-dye decolourization in only 75 min of reaction under very low concentration of clay catalyst (0.05 g/L). PMID:29182560

Petrology of the 1995/2000 Magma of Copahue, Argentina

NASA Astrophysics Data System (ADS)

Goss, A.; Varekamp, J. C.

2001-05-01

Phreatomagmatic eruptions of Copahue in July/August,1995 and July/August 2000 produced mixed juvenile clasts, silica-rich debris from the hydrothermal system, and magmatic scoria with 88 percent SiO2. These high-SiO2 clasts carry an as yet unidentified (crystobalite?), euhedral silica phase in great abundance, which is riddled with tan, primary melt inclusions. The mixed clasts have bands of mafic material with small euhedral olivine, clinopyroxene, and plagioclase that are mixed with an intermediate magma with coarser, resorbed phenocrysts of olivine, plagioclase, clino- and ortho- pyroxene, and rare occurrences of the silica phase. These ejecta are intimate mixtures of a relatively felsic magma similar to Pleistocene Copahue lavas and a mafic basaltic andesite, with minor contributions of a magma contaminated with silica-rich hydrothermal wallrock material. Two-pyroxene geothermometry indicates crystallization temperatures of 1020 deg - 1045 deg C. Glass inclusions (59-63 percent SiO2) in plagioclase and olivine crystals yield very low volatile contents in the melt (0.4-1.5 percent H2O). The 1995/2000 magmas resided at shallow level and degassed into the active volcano-hydrothermal system which discharges acid fluids into the Copahue crater lake and hot springs. More mafic magma intruded this shallow batch and the mixture rose into the hydrothermal system and assimilated siliceous wall rock. A Ti-diffusion profile in a magnetite crystal suggests that the period between magma mixing and eruption was on the order of 4-10 weeks, and the temperature difference between resident and intruding magma was about 50-60 oC.

Mashing up metals with carbothermal shock

NASA Astrophysics Data System (ADS)

Skrabalak, Sara E.

2018-03-01

Different materials and the capabilities they enabled have marked the ages of civilization. For example, the malleable copper alloys of the Bronze Age provided harder and more durable tools. Most exploration of new alloys has focused on random alloys, in which the alloying metal sites have no metal preference. In binary and ternary metal systems, dissimilar elements do not mix readily at high concentrations, which has limited alloying studies to intermetallics (ordered multimetallic phases) and random alloys, in which minor components are added to a principal element. In 2004, crystalline metal alloys consisting of five or more principal elements in equal or nearly equal amounts (1, 2) were reported that were stabilized by their high configurational entropy. Unlike most random alloys, the “high-entropy” alloys (3, 4) reside in the centers of their multidimensional phase diagrams (see the figure, right). On page 1489 of this issue, Yao et al. (5) present an innovative and general route to high-entropy alloys that can mix up to eight elements into single-phase, size-controlled nanoparticles (NPs).

Stabilizing Superionic-Conducting Structures via Mixed-Anion Solid Solutions of Monocarba- closo -borate Salts

DOE PAGES

Tang, Wan Si; Yoshida, Koji; Soloninin, Alexei V.; ...

2016-09-01

Solid lithium and sodium closo-polyborate-based salts are capable of superionic conductivities surpassing even liquid electrolytes, but often only at above-ambient temperatures where their entropically driven disordered phases become stabilized. Here we show by X-ray diffraction, quasielastic neutron scattering, differential scanning calorimetry, NMR, and AC impedance measurements that by introducing 'geometric frustration' via the mixing of two different closo-polyborate anions, namely, 1-CB 9H 10- and CB 11H 12-, to form solid-solution anion-alloy salts of lithium or sodium, we can successfully suppress the formation of possible ordered phases in favor of disordered, fast-ion-conducting alloy phases over a broad temperature range from subambientmore » to high temperatures. Finally, this result exemplifies an important advancement for further improving on the remarkable conductive properties generally displayed by this class of materials and represents a practical strategy for creating tailored, ambient-temperature, solid, superionic conductors for a variety of upcoming all-solid-state energy devices of the future.« less

TANK48 CFD MODELING ANALYSIS

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

Lee, S.

2011-05-17

The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitativemore » mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions as the single-phase model. The modeling results show that the flow patterns driven by four pump operation satisfy the solid suspension requirement, and the average solid concentration at the plane of the transfer pump inlet is about 12% higher than the tank average concentrations for the 70 inch tank level and about the same as the tank average value for the 29 inch liquid level. When one of the four pumps is not operated, the flow patterns are satisfied with the minimum suspension velocity criterion. However, the solid concentration near the tank bottom is increased by about 30%, although the average solid concentrations near the transfer pump inlet have about the same value as the four-pump baseline results. The flow pattern results show that although the two-pump case satisfies the minimum velocity requirement to suspend the sludge particles, it provides the marginal mixing results for the heavier or larger insoluble materials such as MST and KTPB particles. The results demonstrated that when more than one jet are aiming at the same position of the mixing tank domain, inefficient flow patterns are provided due to the highly localized momentum dissipation, resulting in inactive suspension zone. Thus, after completion of the indexed solids suspension, pump rotations are recommended to avoid producing the nonuniform flow patterns. It is noted that when tank liquid level is reduced from the highest level of 70 inches to the minimum level of 29 inches for a given number of operating pumps, the solid mixing efficiency becomes better since the ratio of the pump power to the mixing volume becomes larger. These results are consistent with the literature results.« less

Flow Strength of Shocked Aluminum in the Solid-Liquid Mixed Phase Region

NASA Astrophysics Data System (ADS)

Reinhart, William

2011-06-01

Shock waves have been used to determine material properties under high shock stresses and very-high loading rates. The determination of mechanical properties such as compressive strength under shock compression has proven to be difficult and estimates of strength have been limited to approximately 100 GPa or less in aluminum. The term ``strength'' has been used in different ways. For a Von-Mises solid, the yield strength is equal to twice the shear strength of the material and represents the maximum shear stress that can be supported before yield. Many of these concepts have been applied to materials that undergo high strain-rate dynamic deformation, as in uni-axial strain shock experiments. In shock experiments, it has been observed that the shear stress in the shocked state is not equal to the shear strength, as evidenced by elastic recompressions in reshock experiments. This has led to an assumption that there is a yield surface with maximum (loading)and minimum (unloading), shear strength yet the actual shear stress lies somewhere between these values. This work provides the first simultaneous measurements of unloading velocity and flow strength for transition of solid aluminum to the liquid phase. The investigation describes the flow strength observed in 1100 (pure), 6061-T6, and 2024 aluminum in the solid-liquid mixed phase region. Reloading and unloading techniques were utilized to provide independent data on the two unknowns (τc and τo) , so that the actual critical shear strength and the shear stress at the shock state could be estimated. Three different observations indicate a change in material response for stresses of 100 to 160 GPa; 1) release wave speed (reloading where applicable) measurements, 2) yield strength measurements, and 3) estimates of Poisson's ratio, all of which provide information on the melt process including internal consistency and/or non-equilibrium and rate-dependent melt behavior. The study investigates the strength properties in the solid region and as the material transverses the solid-mixed-liquid regime. Differences observed appear to be the product of alloying and/or microstructural composition of the aluminum. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Highly oriented Bi-based thin films with zero resistance at 106 K

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

Kula, W.; Sobolewski, R.; Gorecka, J.

1991-03-01

This paper reports on fabrication and characterization of nearly single-phase superconducting Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} thin films. The films were dc magnetron sputtered from heavily Pb-doped (Pb/Bi molar ratios up to 1.25), sintered targets on unheated MgO, SrTiO{sub 3}, CaNdAlO{sub 4}, and SrLaAlO{sub 4} single crystals. For the films grown on the (100) oriented MgO substrate, less than 1 hour of annealing in air at 870{degrees} C was sufficient to obtain more than 90% of the 110-K-phase material, with highly c-axis oriented crystalline structure and zero resistivity at 106 K. The films fabricated on the other substrates alsomore » exhibited a narrow superconducting transition and were fully superconducting above 100 K, but they consisted of a mixed-phase material with a large percentage of the 80 K phase.« less

Characterizing the Atomic Structure in Low Concentrations of Weakly Ordered, Weakly Scattering Materials Using the Pair Distribution Function

NASA Astrophysics Data System (ADS)

Terban, Maxwell W.

Nanoscale structural characterization is critical to understanding the physical underpinnings of properties and behavior in materials with technological applications. The work herein shows how the pair distribution function technique can be applied to x-ray total scattering data for material systems which weakly scatter x-rays, a typically difficult task due to the poor signal-to-noise obtained from the structures of interest. Characterization and structural modeling are demonstrated for a variety of molecular and porous systems, along with the detection and characterization of disordered, minority phases and components. In particular, reliable detection and quantitative analysis are demonstrated for nanocrystals of an active pharmaceutical ingredient suspended in dilute solution down to a concentration of 0.25 wt. %, giving a practical limit of detection for ordered nanoscale phases within a disordered matrix. Further work shows that minority nanocrystalline phases can be detected, fingerprinted, and modeled for mixed crystalline and amorphous systems of small molecules and polymers. The crystallization of amorphous lactose is followed under accelerated aging conditions. Melt quenching is shown to produce a different local structure than spray drying or freeze drying, along with increased resistance to crystallization. The initial phases which form in the spray dried formulation are identified as a mixture of polymorphs different from the final alpha-lactose monohydrate form. Hard domain formation in thermoplastic polyurethanes is also characterized as a function of methylene diphenyl diisocyanate and butanediol component ratio, showing that distinct and different hard phase structures can form and are solved by indexing with structures derived from molecular dynamics relaxation. In both cases, phase fractions can be quantified in the mixed crystalline and amorphous systems by fitting with both standards or structure models. Later chapters, demonstrate pair distribution characterization of particle incorporation, structure, and synthesis of nanoporous materials. Nanoparticle size distributions are extracted from platinum nanoparticles nucleating within a zeolite matrix through structural modeling, and validated by transmission electron microscope studies. The structure of zirconium phosphonate-phosphate unconventional metal organic framework is determined to consist of turbostratically disordered nanocrystalline layers of Zr-phenylphosphonate, and the local environment of terbium intercalated between the layers is found to resemble the local environment in scheelite-type terbium phosphate. Finally, the early stages of reaction between aqueous zinc dinitrate hexahydrate and methanolic 2-methylimidazole are characterized using in situ total scattering measurements, showing that secondary building units of tetrahedrally coordinated by 2-methylimidazole initially form upon reaction. Overall, the methodologies are developed and applied toward phase detection, identification, solution, and behavior in pharmaceuticals, polymers, and nanoporous materials along with advice for carrying out experiments and analysis on such materials such that they can be extended to other similar systems.

Method for Improving Mg Doping During Group-III Nitride MOCVD

DOEpatents

Creighton, J. Randall; Wang, George T.

2008-11-11

A method for improving Mg doping of Group III-N materials grown by MOCVD preventing condensation in the gas phase or on reactor surfaces of adducts of magnesocene and ammonia by suitably heating reactor surfaces between the location of mixing of the magnesocene and ammonia reactants and the Group III-nitride surface whereon growth is to occur.

AUTOMATED REMOVAL OF BROMINATED FLAME RETARDANT MATERIAL FROM A MIXED E-WASTE PLASTICS RECYCLING STREAM - PHASE I

EPA Science Inventory

Electronic waste (e-waste) is one of the most rapidly growing waste problems worldwide. Improper handling of e-waste results in vast amounts of toxic waste being sent to landfills and leaching into the water supply. Because of these concerns, e-waste recycling is a rapidly gro...

AUTOMATED REMOVAL OF BROMINATED FLAME RETARDANT MATERIAL FROM A MIXED E-WASTE PLASTICS RECYCLING STREAM - PHASE II

EPA Science Inventory

Electronic waste (e-waste) is one of the most rapidly growing waste problems worldwide. Improper handling of e-waste results in vast amounts of toxic waste being sent to landfill and leaching into the water supply. Due to there concerns e-waste recycling is a rapidly growing...

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

Chang, Chong

We present a simple approach for determining ion, electron, and radiation temperatures of heterogeneous plasma-photon mixtures, in which temperatures depend on both material type and morphology of the mixture. The solution technique is composed of solving ion, electron, and radiation energy equations for both mixed and pure phases of each material in zones containing random mixture and solving pure material energy equations in subdivided zones using interface reconstruction. Application of interface reconstruction is determined by the material configuration in the surrounding zones. In subdivided zones, subzonal inter-material energy exchanges are calculated by heat fluxes across the material interfaces. Inter-material energymore » exchange in zones with random mixtures is modeled using the length scale and contact surface area models. In those zones, inter-zonal heat flux in each material is determined using the volume fractions.« less

Method for producing nanocrystalline multicomponent and multiphase materials

DOEpatents

Eastman, Jeffrey A.; Rittner, Mindy N.; Youngdahl, Carl J.; Weertman, Julia R.

1998-01-01

A process for producing multi-component and multiphase nanophase materials is provided wherein a plurality of elements are vaporized in a controlled atmosphere, so as to facilitate thorough mixing, and then condensing and consolidating the elements. The invention also provides for a multicomponent and multiphase nanocrystalline material of specified elemental and phase composition having component grain sizes of between approximately 1 nm and 100 nm. This material is a single element in combination with a binary compound. In more specific embodiments, the single element in this material can be a transition metal element, a non-transition metal element, a semiconductor, or a semi-metal, and the binary compound in this material can be an intermetallic, an oxide, a nitride, a hydride, a chloride, or other compound.

Raman Scattering in a New Carbon Material

NASA Technical Reports Server (NTRS)

Voronov, O. A.; Street, K. W., Jr.

2010-01-01

Samples of a new carbon material, Diamonite-B, were fabricated under high pressure from a commercial carbon black--identified as mixed fullerenes. The new material is neither graphite-like nor diamond-like, but exhibits electrical properties close to graphite and mechanical properties close to diamond. The use of Raman spectroscopy to investigate the vibrational dynamics of this new carbon material and to provide structural characterization of its short-, medium- and long-range order is reported. We also provide the results of investigations of these samples by high-resolution electron microscopy and X-ray diffraction. Hardness, electrical conductivity, thermal conductivity and other properties of this new material are compared with synthetic graphite-like and diamond-like materials, two other phases of synthetic bulk carbon.

Simulation of Ejecta Production and Mixing Process of Sn Sample under shock loading

NASA Astrophysics Data System (ADS)

Wang, Pei; Chen, Dawei; Sun, Haiquan; Ma, Dongjun

2017-06-01

Ejection may occur when a strong shock wave release at the free surface of metal material and the ejecta of high-speed particulate matter will be formed and further mixed with the surrounding gas. Ejecta production and its mixing process has been one of the most difficult problems in shock physics remain unresolved, and have many important engineering applications in the imploding compression science. The present paper will introduce a methodology for the theoretical modeling and numerical simulation of the complex ejection and mixing process. The ejecta production is decoupled with the particle mixing process, and the ejecta state can be achieved by the direct numerical simulation for the evolution of initial defect on the metal surface. Then the particle mixing process can be simulated and resolved by a two phase gas-particle model which uses the aforementioned ejecta state as the initial condition. A preliminary ejecta experiment of planar Sn metal Sample has validated the feasibility of the proposed methodology.

Distribution, physical state and mixing of materials at the surface of Pluto from New Horizons

NASA Astrophysics Data System (ADS)

Schmitt, Bernard; Philippe, Sylvain; Grundy, Will; Reuter, D. C.; Quirico, Eric; Protopapa, Silvia; Côte, Rémi; Young, Leslie; Binzel, Richard; Cook, Jason C.; Cruikshank, Dale P.; Dalle Ore, Cristina M.; Earle, Alissa M.; Ennico, Kimberly; Howett, Carly; Jennings, Donald; Linscott, Ivan; Lunsford, A. W.; Olkin, Catherine B.; Parker, Joel Wm.; Parker, Alex; Singer, Kelsi N.; Spencer, John R.; Stansberry, John A.; Stern, S. Alan; Tsang, Constantine; Verbiscer, Anne J.; Weaver, Harold A.; New Horizons Science Team

2016-10-01

In July 2015 the New Horizons spacecraft recorded a large set of data on Pluto, in particular with the LEISA spectro-imager dedicated to the study of the surface composition.In this talk we report a study of the distribution and physical state of the ices and non-ice materials on Pluto's surface and their mode and degree of mixing. Principal Component analysis as well as specific spectral indicators and correlation plots are used on high resolution LEISA spectro-images covering the whole illuminated face of Pluto. Qualitative distribution maps have been obtained for the 4 main condensed molecules, N2, CH4, CO, H2O as well as for the visible-dark red material. These maps indicate the presence of 3 different types of ices: N2-rich:CH4:CO ices, CH4-rich:(CO:N2?) ices and H2O ice. Their mixing lines and with the dark reddish material are studied. CH4 is mixed at the molecular level with N2 and CO, thus forming a ternary molecular mixture that follows its phase diagram with low solubility limits. The occurrence of a N2-rich - CH4-rich ices mixing line associated with a decrease of the CO/CH4 ratio tell us that a fractionation sublimation sequence transforms N2-rich ice into either a N2-rich - CH4-rich binary mixture at the surface or an upper CH4-rich(:CO:N2) ice crust that may hide the N2-rich ice below. The CH4-rich - H2O mixing line witnesses the subsequent sublimation of CH4 ice left behind by the N2:CO sublimation (N spring-summer), or a direct condensation of CH4 ice on cold H2O ice (S autumn). The very sharp spatial transitions between CH4-containing ices and the dark red material are probably due to thermal incompatibility. Finally there is some spatial mixing of the reddish material covering H2O ice. H2O ice appears to be the substratum on which other ices condense or non-volatile organic material is deposited from the atmosphere. The spatial distribution of these materials is very complex.The high spatial definition of all these composition maps will allow us to compare them with Pluto's geologic features observed by LORRI panchromatic and MVIC multispectral imagers to better understand the geophysical processes in action at the surface of this astonishingly active cold world.

Mesoporous mixed-phase Ga{sub 2}O{sub 3}: Green synthesis and enhanced photocatalytic activity

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

Liu, Jin; The Key Laboratory of Rare Earth Functional Materials and Applications, Zhoukou Normal University, Zhoukou 466001; Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn

2015-08-15

Highlights: • Mixed-phase Ga{sub 2}O{sub 3} was synthesized by a facile and green method. • Mixed-phase Ga{sub 2}O{sub 3} exhibited good photocatalytic activity and stability. • The reactive species in the photocatalytic process were investigated. - Abstract: Mesoporous mixed-phase Ga{sub 2}O{sub 3} was synthesized by calcining the GaOOH precursor. The composition, crystal phase and microstructures of Ga{sub 2}O{sub 3} were characterized in detail. The phase composition of the as-prepared Ga{sub 2}O{sub 3} depended on the calcination temperature and the mixed-phase Ga{sub 2}O{sub 3} was obtained at 600–700 °C. As compared to the pure-phase α-Ga{sub 2}O{sub 3} and β-Ga{sub 2}O{sub 3},more » the mixed-phase Ga{sub 2}O{sub 3} exhibited an enhanced photocatalytic property for the degradation of metronidazole solution. The heterojunction in the mixed-phase Ga{sub 2}O{sub 3} was beneficial to the separation of photogenerated electrons and holes. Moreover, the mixed-phase Ga{sub 2}O{sub 3} possessed mesopore structure, which increased more reaction sites and was in favor of the contact of metronidazole molecules with reaction sites. The recycling experiments show that the mixed-phase Ga{sub 2}O{sub 3} has good stability and can be separated easily from the reaction system.« less

Hot-water and solid-phase extraction of fluorescent whitening agents in paper materials and infant clothes followed by unequivocal determination with ion-pair chromatography-tandem mass spectrometry.

PubMed

Chen, Hsin-Chang; Ding, Wang-Hsien

2006-03-10

A comprehensive method for the determination of four stilbene-type disulfonate and one distyrylbiphenyl-type fluorescent whitening agents (FWAs) in paper materials (napkin and paper tissue) and infant clothes was developed. FWAs were extracted from paper material and cloth samples using a hot-water extraction, and the aqueous extracts were then preconcentrated with the newly developed Oasis WAX (mixed-mode of weak anion exchange and reversed-phase sorbent) solid-phase extraction cartridge. The analytes were unequivocal determined by ion pair chromatography coupled with negative electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS-MS), applying a di-n-hexyl-ammonium acetate (DHAA) as the ion-pairing reagent in mobile phase. Limits of quantitation (LOQ) were established between 0.2 and 0.9 ng/g in 2 g of samples. Recovery of five FWAs in spiked commercial samples was between 42 and 95% and RSD (n = 3) ranging from 2 to 11%. The method was finally applied to commercial samples, showing that two stilbene-type disulfonates were predominant FWAs detected in napkin and infant cloth samples.

Anisotropic imprint of amorphization and phase separation in manganite thin films via laser interference irradiation.

PubMed

Ding, Junfeng; Lin, Zhipeng; Wu, Jianchun; Dong, Zhili; Wu, Tom

2015-02-04

Materials with mesoscopic structural and electronic phase separation, either inherent from synthesis or created via external means, are known to exhibit functionalities absent in the homogeneous counterparts. One of the most notable examples is the colossal magnetoresistance discovered in mixed-valence manganites, where the coexistence of nano- to micrometer-sized phase-separated domains dictates the magnetotransport. However, it remains challenging to pattern and process such materials into predesigned structures and devices. In this work, a direct laser interference irradiation (LII) method is employed to produce periodic stripes in thin films of a prototypical phase-separated manganite Pr0.65 (Ca0.75 Sr0.25 )0.35 MnO3 (PCSMO). LII induces selective structural amorphization within the crystalline PCSMO matrix, forming arrays with dimensions commensurate with the laser wavelength. Furthermore, because the length scale of LII modification is compatible to that of phase separation in PCSMO, three orders of magnitude of increase in magnetoresistance and significant in-plane transport anisotropy are observed in treated PCSMO thin films. Our results show that LII is a rapid, cost-effective and contamination-free technique to tailor and improve the physical properties of manganite thin films, and it is promising to be generalized to other functional materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of new superficially porous particles with carbon core and nanodiamond-polymer shell for proteins characterization.

PubMed

Bobály, Balázs; Guillarme, Davy; Fekete, Szabolcs

2015-02-01

A new superficially porous material possessing a carbon core and nanodiamond-polymer shell and pore size of 180Å was evaluated for the analysis of large proteins. Because the stationary phase on this new support contains a certain amount of protonated amino groups within the shell structure, the resulting retention mechanism is most probably a mix between reversed phase and anion exchange. However, under the applied conditions (0.1-0.5% TFA in the mobile phase), it seemed that the main retention mechanism for proteins was hydrophobic interaction with the C18 alkylchains on this carbon based material. In this study, we demonstrated that there was no need to increase mobile phase temperature, as the peak capacity was not modified considerably between 30 and 80°C for model proteins. Thus, the risk of thermal on-column degradation or denaturation of large proteins is not relevant. Another important difference compared to silica-based materials is that this carbon-based column requires larger amount of TFA, comprised between 0.2 and 0.5%. Finally, it is important to mention that selectivity between closely related proteins (oxidized, native and reduced forms of Interferon α-2A variants) could be changed mostly through mobile phase temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System

PubMed Central

Ma, Biao; Zhou, Xue-yan; Liu, Jiang; You, Zhanping; Wei, Kun; Huang, Xiao-feng

2016-01-01

Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are −18 °C–7 °C, 7 °C–25 °C and 25 °C–44 °C, respectively, and that of the asphalt mixture are −18 °C~10 °C, −10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method. PMID:28773510

Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System.

PubMed

Ma, Biao; Zhou, Xue-Yan; Liu, Jiang; You, Zhanping; Wei, Kun; Huang, Xiao-Feng

2016-05-19

Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are -18 °C-7 °C, 7 °C-25 °C and 25 °C-44 °C, respectively, and that of the asphalt mixture are -18 °C~10 °C, -10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method.

The behavior of osmium and other siderophile elements during impacts: Insights from the Ries impact structure and central European tektites

NASA Astrophysics Data System (ADS)

Ackerman, Lukáš; Magna, Tomáš; Žák, Karel; Skála, Roman; Jonášová, Šárka; Mizera, Jiří; Řanda, Zdeněk

2017-08-01

Impact processes are natural phenomena that contribute to a variety of physico-chemical mechanisms over an extreme range of shock pressures and temperatures, otherwise seldomly achieved in the Earth's crust through other processes. Under these extreme conditions with transient temperatures and pressures ≥3000 K and ≥100 GPa, followed by their rapid decrease, the behavior of elements has remained poorly understood. Distal glassy ejecta (tektites) were produced in early phases of contact between the Earth's surface and an impacting body. Here we provide evidence for a complex behavior of Os and other highly siderophile elements (HSE; Ir, Ru, Pt, Pd, and Re) during tektite production related to a hyper-velocity impact that formed the Ries structure in Germany. Instead of simple mixing between the surface materials, which are thought to form the major source of central European tektites (moldavites), and impactor matter, the patterns of HSE contents and 187Re/188Os - 187Os/188Os ratios in moldavites, target sediments and impact-related breccias (suevites) can be explained by several sequential and/or contemporary processes. These involve (i) evaporative loss of partially oxidized HSE from the overheated tektite melt, (ii) mixing of target-derived and impactor-derived HSE vapor (plasma) phases, and (iii) early (high-temperature) condensation of a part of the mixed vapor phase back to silicate melt droplets. An almost complete loss of terrestrial Os from the tektite melt and its replacement with extra-terrestrial Os are indicated by low 187Os/188Os ratios in tektites (<0.163) relative to precursor materials (>0.69). This is paralleled by a co-variation between Os and Ni contents in tektites but not in suevites formed later in the impact process.

Effect of nanocomposite synthesis on the combustion performance of a ternary thermite.

PubMed

Prentice, Daniel; Pantoya, Michelle L; Clapsaddle, Brady J

2005-11-03

Nanocomposite thermites are attractive materials for their diverse applications from metallurgy to ordnance technologies. While there are a plethora of combinations of fuel and oxidizers, this work shows that the composite's overall performance is intimately tied to how the fuel and oxidizer are prepared and combined. Comparison of the combustion velocities of two separate ternary mixtures of Al-Fe(2)O(3)-SiO(2), one prepared in situ using sol-gel processing and the other prepared by physically mixing discrete nanoscale particles, demonstrated different burning behaviors as a result of preparation technique. The stoichiometry of the two sets of thermite was varied to examine the influence of SiO(2) on combustion velocity as a means to control the reaction behavior. For pure Fe(2)O(3) + Al reactions, results show that the sol-gel synthesized materials (40 m/s) exhibit increased velocities over the physically mixed materials (9 m/s) by approximately 4 times. This trend is not observed, however, upon addition of SiO(2) to the thermite mixture; ternary thermites with 40 wt % SiO(2) showed decreased burn velocities of 0.02 m/s for sol-gel prepared thermites compared to 0.2 m/s for their physically mixed counterparts. The observed trends are believed to be caused by the unique mixing between the Fe(2)O(3) and SiO(2) phases resulting from the two synthesis techniques.

Shear Bond Strengths between Three Different Yttria-Stabilized Zirconia Dental Materials and Veneering Ceramic and Their Susceptibility to Autoclave Induced Low-Temperature Degradation.

PubMed

Sehgal, Manoti; Bhargava, Akshay; Gupta, Sharad; Gupta, Prateek

2016-01-01

A study was undertaken to evaluate the effect of artificial aging through steam and thermal treatment as influencing the shear bond strength between three different commercially available zirconia core materials, namely, Upcera, Ziecon, and Cercon, layered with VITA VM9 veneering ceramic using Universal Testing Machine. The mode of failure between zirconia and ceramic was further analyzed as adhesive, cohesive, or mixed using stereomicroscope. X-ray diffraction and SEM (scanning electron microscope) analysis were done to estimate the phase transformation (m-phase fraction) and surface grain size of zirconia particles, respectively. The purpose of this study was to simulate the clinical environment by artificial aging through steam and thermal treatment so as the clinical function and nature of the bond between zirconia and veneering material as in a clinical trial of 15 years could be evaluated.

Aluminum-26 in the early solar system - Fossil or fuel

NASA Technical Reports Server (NTRS)

Lee, T.; Papanastassiou, D. A.; Wasserburg, G. J.

1977-01-01

The isotopic composition of Mg was measured in different phases of a Ca-Al-rich inclusion in the Allende meteorite. Large excesses of Mg-26 of up to 10% were found. These excesses correlate strictly with the Al-27/Mg-24 ratio for four coexisting phases with distinctive chemical compositions. Models of in situ decay of Al-26 within the solar system and of mixing of interstellar dust grains containing fossil Al-26 with normal solar system material are presented. The observed correlation provides definitive evidence for the presence of Al-26 in the early solar system. This requires either injection of freshly synthesized nucleosynthetic material into the solar system immediately before condensation and planet formation, or local production within the solar system by intense activity of the early sun. Planets promptly produced from material with the inferred Al-26/Al-27 would melt within about 300,000 years.

The design of aircraft brake systems, employing cooling to increase brake life

NASA Technical Reports Server (NTRS)

Scaringe, R. P.; Ho, T. L.; Peterson, M. B.

1975-01-01

A research program was initiated to determine the feasibility of using cooling to increase brake life. An air cooling scheme was proposed, constructed and tested with various designs. Straight and curved slotting of the friction material was tested. A water cooling technique, similar to the air cooling procedure, was evaluated on a curved slotted rotor. Also investigated was the possibility of using a phase-change material within the rotor to absorb heat during braking. Various phase-changing materials were tabulated and a 50%, (by weight) LiF - BeF2 mixing was chosen. It was shown that corrosion was not a problem with this mixture. A preliminary design was evaluated on an actual brake. Results showed that significant improvements in lowering the surface temperature of the brake occurred when air or water cooling was used in conjunction with curved slotted rotors.

Combining Advanced Turbulent Mixing and Combustion Models with Advanced Multi-Phase CFD Code to Simulate Detonation and Post-Detonation Bio-Agent Mixing and Destruction

DTIC Science & Technology

2017-10-01

perturbations in the energetic material to study their effects on the blast wave formation. The last case also makes use of the same PBX, however, the...configuration, Case A: Spore cloud located on the top of the charge at an angle 45 degree, Case B: Spore cloud located at an angle 45 degree from the charge...theoretical validation. The first is the Sedov case where the pressure decay and blast wave front are validated based on analytical solutions. In this test

Band Alignment-Driven Oxidative Injury to the Skin by Anatase/Rutile Mixed-Phase Titanium Dioxide Nanoparticles under Sunlight Exposure.

PubMed

Sun, Xiujuan; Chang, Yun; Cheng, Yan; Feng, Yanlin; Zhang, Haiyuan

2018-04-12

Anatase/rutile mixed-phase titanium dioxide (TiO2) nanoparticles (NPs) have been found in cosmetics and cotton textiles. Once exposed to sunlight, mixed-phase TiO2 NPs are even more toxic to cells than pure phase NPs, however, the underlying mechanism remains unclear. Considering the unique anatase/rutile heterojunction structure existing in mixed-phase NPs, the potent toxicity of mixed-phase TiO2 NPs probably originates from the high reactive oxygen species (ROS) production because the anatase/rutile heterojunction is constituted by the staggered energy bands that facilitate the electron-hole separation at the interface due to the band alignment. In the present study, a library of mixed-phase TiO2 NPs with different anatase/rutile ratios was established to investigate the potential property-activity relationship and further clarify the underlying molecular mechanism. Under sunlight exposure, these mixed-phase TiO2 NPs could produce significant abiotic ROS and induce hierarchical oxidative stress to HaCaT skin cells and mice skin. The ROS magnitude and toxicity potential of these NPs were found to be proportional to their energy band bending (BB) levels. This means that the toxicity of mixed-phase TiO2 NPs can be correlated to their heterojunction density, and the toxicity potential of mixed-phase TiO2 NPs can be weighed by their BB levels.

Directional nonlinear guided wave mixing: Case study of counter-propagating shear horizontal waves

NASA Astrophysics Data System (ADS)

Hasanian, Mostafa; Lissenden, Cliff J.

2018-04-01

While much nonlinear ultrasonics research has been conducted on higher harmonic generation, wave mixing provides the potential for sensitive measurements of incipient damage unencumbered by instrumentation nonlinearity. Studies of nonlinear ultrasonic wave mixing, both collinear and noncollinear, for bulk waves have shown the robust capability of wave mixing for early damage detection. One merit of bulk wave mixing lies in their non-dispersive nature, but guided waves enable inspection of otherwise inaccessible material and a variety of mixing options. Co-directional guided wave mixing was studied previously, but arbitrary direction guided wave mixing has not been addressed until recently. Wave vector analysis is applied to study variable mixing angles to find wave mode triplets (two primary waves and a secondary wave) resulting in the phase matching condition. As a case study, counter-propagating Shear Horizontal (SH) guided wave mixing is analyzed. SH wave interactions generate a secondary Lamb wave mode that is readily receivable. Reception of the secondary Lamb wave mode is compared for an angle beam transducer, an air coupled transducer, and a laser Doppler vibrometer (LDV). Results from the angle beam and air coupled transducers are quite consistent, while the LDV measurement is plagued by variability issues.

Control of Silver Diffusion in Low-Temperature Co-Fired Diopside Glass-Ceramic Microwave Dielectrics

PubMed Central

Chou, Chen-Chia; Chang, Chun-Yao; Chen, Guang-Yu; Feng, Kuei-Chih; Tsao, Chung-Ya

2017-01-01

Electrode material for low-temperature co-fired diopside glass-ceramic used for microwave dielectrics was investigated in the present work. Diffusion of silver from the electrode to diopside glass-ceramics degrades the performance of the microwave dielectrics. Two approaches were adopted to resolve the problem of silver diffusion. Firstly, silicon-oxide (SiO2) powder was employed and secondly crystalline phases were chosen to modify the sintering behavior and inhibit silver ions diffusion. Nanoscale amorphous SiO2 powder turns to the quartz phase uniformly in dielectric material during the sintering process, and prevents the silver from diffusion. The chosen crystalline phase mixing into the glass-ceramics enhances crystallinity of the material and inhibits silver diffusion as well. The result provides a method to decrease the diffusivity of silver ions by adding the appropriate amount of SiO2 and appropriate crystalline ceramics in diopside glass-ceramic dielectric materials. Finally, we used IEEE 802.11a 5.8 GHz as target specification to manufacture LTCC antenna and the results show that a good broadband antenna was made using CaMgSi2O6 with 4 wt % silicon oxide. PMID:29286330

Induction of optical vortex in the crystals subjected to bending stresses.

PubMed

Skab, Ihor; Vasylkiv, Yurij; Vlokh, Rostyslav

2012-08-20

We describe a method for generation of optical vortices that relies on bending of transparent parallelepiped-shaped samples fabricated from either glass or crystalline solid materials. It is shown that the induced singularity of optical indicatrix rotation leads in general to appearance of a mixed screw-edge dislocation of the phase front of outgoing optical beam. At the same time, some specified geometrical parameters of the sample can ensure generation of a purely screw dislocation of the phase front and, as a result, a singly charged canonical optical vortex.

Novel Electro-Analytical Tools for Phase-Transformation Electrode Materials

DTIC Science & Technology

2009-08-13

words) We measured and compared phase transformation accommodation energy (AE) for Li4Ti5O12 and LiFePO4 with different particle size by using...larger than next cycles due to inducing of defects; Because of smaller volume difference, AE of Li4Ti5O12 was lower than that of LiFePO4 ; AE of... LiFePO4 with small particle size was lower than that of LiFePO4 with large particle size. By plugging the AE measured by GITT into mixed control

Custom-designed nanomaterial libraries for testing metal oxide toxicity

PubMed Central

Pokhrel, Suman; Nel, André E.; Mädler, Lutz

2014-01-01

Conspectus Advances in aerosol technology over the past 10 years have provided methods that enable the generation and design of ultrafine nanoscale materials for different applications. The particles are produced combusting a precursor solution and its chemical reaction in the in the gas phase. Flame spray pyrolysis (FSP) is a highly versatile technique for single step and scalable synthesis of nanoscale materials. New innovations in particle synthesis using FSP technology and its precursor chemistry have enabled flexible dry synthesis of loosely-agglomerated highly crystalline ultrafine powders (porosity ≥ 90%) of binary, ternary and mixed binary or ternary oxides. The flame spray pyrolysis lies at the intersection of combustion science, aerosols technology and materials chemistry. The interdisciplinary research is not only inevitable but is becoming increasingly crucial in the design of nanoparticles (NPs) made in the gas phase. The increasing demand especially in the bio-applications for particles with specific material composition, high purity and crystallinity can be often fulfilled with the fast, single step FSP technique. PMID:23194152

Microstructural and Mechanical Characterization of Ti-12Mo-6Zr Biomaterials Fabricated by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Daoush, Walid Mohamed Rashad Mohamed; Park, Hee Sup; Inam, Fawad; Lim, Byung Kyu; Hong, Soon Hyung

2015-03-01

Ti-12Mo-6Zr/Al2O3 (titanium biomaterial) was prepared by a powder metallurgy route using Spark Plasma Sintering (SPS). Ti, Mo, and Zr powders were mixed by wet milling with different content of alumina nanoparticles (up to 5 wt pct) as an oxide dispersion strengthening phase. Composite powder mixtures were SPSed at 1273 K (1000 °C) followed by heat treatment and quenching. Composite powders, sintered materials, and heat-treated materials were examined using optical and high-resolution electronic microscopy (scanning and transmission) and X-ray diffraction to characterize particle size, surface morphology, and phase identifications for each composition. All sintered materials were evaluated by measuring density, Vickers hardness, and tensile properties. Fully dense sintered materials were produced by SPS and mechanical properties were found to be improved by subsequent heat treatment. The tensile properties as well as the hardness were increased by increasing the content of Al2O3 nanoparticles in the Ti-12Mo-6Zr matrix.

Effect of low-temperature degradation on the mechanical and microstructural properties of tooth-colored 3Y-TZP ceramics.

PubMed

Nakamura, K; Harada, A; Ono, M; Shibasaki, H; Kanno, T; Niwano, Y; Adolfsson, E; Milleding, P; Örtengren, U

2016-01-01

The aim of the present study was to evaluate the effects of low-temperature degradation (LTD) induced by autoclaving on the mechanical and microstructural properties of tooth-colored 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP). In total, 162 disc-shaped 3Y-TZP specimens were prepared. Two-thirds of the specimens were shaded by either the infiltration or powder mixing methods while the remaining specimens were used without coloring. The specimens were autoclaved at 134 °C for 0, 10, and 100 h to induce LTD (n=18 for each group). Chemical compositions were analyzed with X-ray fluorescence spectroscopy. Biaxial flexural strength was measured using a piston-on-three-ball test. The surface fraction and penetration depth of the monoclinic phase were examined using X-ray diffraction and scanning electron microscopy, respectively. The tooth-colored 3Y-TZP specimens contained Fe2O3 and Er2O3 (infiltration technique), and Fe2O3 (powder mixing method) at concentrations of<0.5 wt%. The tooth-colored 3Y-TZP had higher strength than the non-colored material after 100 h of autoclaving. In terms of surface fraction and penetration depth, the generation of monoclinic phase was significantly lower in the tooth-colored 3Y-TZP than in the non-colored material. The tooth-colored 3Y-TZP possessed equivalent biaxial flexural strength to that of the non-colored material and higher resistance to LTD regardless of the coloring technique (infiltration technique or powder mixing method) when the coloring pigments were contained at concentrations used in the present study. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of halide composition on the structural, electronic, and optical properties of mixed CH3NH3Pb (I1-xBrx) 3 perovskites calculated using the virtual crystal approximation method

NASA Astrophysics Data System (ADS)

Jong, Un-Gi; Yu, Chol-Jun; Ri, Jin-Song; Kim, Nam-Hyok; Ri, Guk-Chol

2016-09-01

Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite CH3NH3PbI3 in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites CH3NH3Pb (I1-xBrx) 3 with a pseudocubic phase using the virtual crystal approximation method within density functional theory. With an increase of Br content x from 0.0 to 1.0, the lattice constant decreases in proportion to x with the function of a (x )=6.420 -0.333 x (Å), while the band gap and the exciton binding energy increase with the quadratic function of Eg(x ) =1.542 +0.374 x +0.185 x2 (eV) and the linear function of Eb(x ) =0.045 +0.057 x (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at x ≈0.2 in CH3NH3Pb (I1-xBrx) 3 perovskites.

Characteristics Buton Natural Asphalt-Rubber (BNA-R) on the Performance Improvement of Warm Mix Asphalt Using Natural Zeolite

NASA Astrophysics Data System (ADS)

Wahjuningsih, Nurul; Pranowo Hadiwardoyo, Sigit; Jachrizal Sumabrata, R.

2018-03-01

The decrease in the ability of service of pavement can be caused by the durability factor in the pavement layer in receiving heavy traffic load and the temperature of the pavement. Permanent deformation is one of the criteria of failure of asphalt mixture. Performance assessment of the asphalt mixture can be observed from the rheological properties of asphalt binder. The use of BNA-R in this study is intended to modify the characteristics of bitumen penetration grade 60 / 70 used in warm mix asphalt. Warm mix asphalt with lower temperatures of mixing and compaction than conventional asphalt mixtures was chosen because it is more environmentally friendly. To reduce the temperature in this warm asphalt technology is achieved by using natural zeolite. Both of these materials are local materials that are widely available in Indonesia. The rheology of asphalt 60/70 modified with BNA-R indicates that the addition of BNA-R in the base asphalt increase the complex modulus value and decrease the phase angle value. These values were related to the performance of mixture in the permanent deformation criteria. Reducing the temperature of mixing and compaction should be balanced with modifying the asphalt binder used. Rutting due to permanent deformation can resulted in inconvenience to the passengers and can lead to high costs of road maintenance. To determine the permanent deformation of asphalt mix with material combinations was performed through the wheel tracking test machine with 3,780 cycles for 3 hours. The results shows that after test track over 7 thousand passes have seen permanent deformation characteristics of asphalt concrete mixture with a variation of the characteristics of bitumen.

Polymeric additives to enhance the functional properties of calcium phosphate cements

PubMed Central

Perez, Roman A; Kim, Hae-Won

2012-01-01

The vast majority of materials used in bone tissue engineering and regenerative medicine are based on calcium phosphates due to their similarity with the mineral phase of natural bone. Among them, calcium phosphate cements, which are composed of a powder and a liquid that are mixed to obtain a moldable paste, are widely used. These calcium phosphate cement pastes can be injected using minimally invasive surgery and adapt to the shape of the defect, resulting in an entangled network of calcium phosphate crystals. Adding an organic phase to the calcium phosphate cement formulation is a very powerful strategy to enhance some of the properties of these materials. Adding some water-soluble biocompatible polymers in the calcium phosphate cement liquid or powder phase improves physicochemical and mechanical properties, such as injectability, cohesion, and toughness. Moreover, adding specific polymers can enhance the biological response and the resorption rate of the material. The goal of this study is to overview the most relevant advances in this field, focusing on the different types of polymers that have been used to enhance specific calcium phosphate cement properties. PMID:22511991

Iron-phosphate ceramics for solidification of mixed low-level waste

DOEpatents

Aloy, Albert S.; Kovarskaya, Elena N.; Koltsova, Tatiana I.; Macheret, Yevgeny; Medvedev, Pavel G.; Todd, Terry

2000-01-01

A method of immobilizing mixed low-level waste is provided which uses low cost materials and has a relatively long hardening period. The method includes: forming a mixture of iron oxide powders having ratios, in mass %, of FeO:Fe.sub.2 O.sub.3 :Fe.sub.3 O.sub.4 equal to 25-40:40-10:35-50, or weighing a definite amount of magnetite powder. Metallurgical cinder can also be used as the source of iron oxides. A solution of the orthophosphoric acid, or a solution of the orthophosphoric acid and ferric oxide, is formed and a powder phase of low-level waste and the mixture of iron oxide powders or cinder (or magnetite powder) is also formed. The acid solution is mixed with the powder phase to form a slurry with the ratio of components (mass %) of waste:iron oxide powders or magnetite:acid solution=30-60:15-10:55-30. The slurry is blended to form a homogeneous mixture which is cured at room temperature to form the final product.

XRD investigation of the Effect of MgO Additives on ZTA-TiO2 Ceramic Composites

NASA Astrophysics Data System (ADS)

Azhar, Ahmad Zahirani Ahmad; Manshor, Hanisah; Ali, Afifah Mohd

2018-01-01

Alumina (Al2O3) based ceramics possess good mechanical properties and suitable for the application of cutting inserts. However, this monolithic ceramics suffer from lack of toughness. Hence, there are some modification were made such as the addition of yttria stabilized zirconia (YSZ) to the Al2O3 helps in increasing the toughness of the Al2O3 ceramics. Some additives such as MgO and TiO2 were used to further improve the mechanical properties of ZTA. In this study, high purity raw materials which consist of ZTA-TiO2 were mixed with different amount of MgO (0.0 - 1.0 wt %). The mixture of materials was going through wet mixing, compaction and pressureless sintering at 1600°C for one hour. The samples were characterized for phase analysis, microstructure, shrinkage rate, bulk density, Vickers hardness and fracture toughness. Based on the XRD analysis results, the secondary phase (MgAl2O4) was detected in the sample with 0.5 wt% of MgO onwards which leads to grains refinement, thus improve the density and hardness of ZTA-TiO2-MgO ceramics composites.

Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch

NASA Astrophysics Data System (ADS)

Cozic, J.; Verheggen, B.; Mertes, S.; Connolly, P.; Bower, K.; Petzold, A.; Baltensperger, U.; Weingartner, E.

2007-04-01

The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (droplets and ice particles) as well as interstitial (unactivated) aerosol particles; an interstitial inlet which collected only interstitial aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the condensed phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (FScav,BC), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from FScav,BC=60% in liquid phase clouds to FScav,BC~5-10% in mixed-phase clouds with IMF>0.2. This can be explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour.

Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch

NASA Astrophysics Data System (ADS)

Cozic, J.; Verheggen, B.; Mertes, S.; Connolly, P.; Bower, K.; Petzold, A.; Baltensperger, U.; Weingartner, E.

2006-11-01

The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (drops and ice particles) as well as interstitial aerosol particles; an interstitial inlet which collected only interstitial (unactivated) aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the cloud phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (FScav,BC), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from FScav,BC=60% in liquid phase clouds to FScav,BC~10% in mixed-phase clouds with IMF>0.2. This is explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour.

Optical properties of selected components of mineral dust aerosol processed with organic acids and humic material

NASA Astrophysics Data System (ADS)

Alexander, Jennifer M.; Grassian, V. H.; Young, M. A.; Kleiber, P. D.

2015-03-01

Visible light scattering phase function and linear polarization profiles of mineral dust components processed with organic acids and humic material are measured, and results are compared to T-matrix simulations of the scattering properties. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acids. Clear differences in light scattering properties are observed for all three processed samples when compared to the unprocessed dust or organic salt products. Results for quartz processed with humic acid sodium salt (NaHA) indicate the presence of both internally mixed quartz-NaHA particles and externally mixed NaHA aerosol. Simulations of light scattering suggest that the processed quartz particles become more moderate in shape due to the formation of a coating of humic material over the mineral core. Experimental results for calcite reacted with acetic acid are consistent with an external mixture of calcite and the reaction product, calcium acetate. Modeling of the light scattering properties does not require any significant change to the calcite particle shape distribution although morphology changes cannot be ruled out by our data. It is expected that calcite reacted with oxalic acid will produce internally mixed particles of calcite and calcium oxalate due to the low solubility of the product salt. However, simulations of the scattering for the calcite-oxalic acid system result in rather poor fits to the data when compared to the other samples. The poor fit provides a less accurate picture of the impact of processing in the calcite-oxalic acid system.

Vibrational contributions to the phase stability of PbS-PbTe alloys

NASA Astrophysics Data System (ADS)

Doak, Jeff W.; Wolverton, C.; OzoliĆš, Vidvuds

2015-11-01

The thermoelectric figure of merit (Z T ) of semiconductors such as PbTe can be improved by forming nanostructures within the bulk of these materials. Alloying PbTe with PbS causes PbS-rich nanostructures to precipitate from the solid solution, scattering phonons and increasing Z T . Understanding the thermodynamics of this process is crucial to optimizing the efficiency gains of this technique. Previous calculations of the thermodynamics of PbS-PbTe alloys [(J. W. Doak and C. Wolverton, Phys. Rev. B 86, 144202 (2012), 10.1103/PhysRevB.86.144202] found that mixing energetics alone were not sufficient to quantitatively explain the thermodynamic driving force for phase separation in these materials: first-principles calculations of the thermodynamics of phase separation overestimate the thermodynamic driving force for precipitation of PbS-rich nanostructures from PbS-PbTe alloys. In this work, we re-examine the thermodynamics of PbS-PbTe, including the effects of vibrational entropy in the free energy through frozen-phonon calculations of special quasirandom structures (SQS) to explain this discrepancy between first-principles and experimental phase stability. We find that vibrational entropy of mixing reduces the calculated maximum miscibility gap temperature TG of PbS-PbTe by 470 K, bringing the error between calculated and experimental TG down from 700 to 230 K. Our calculated vibrational spectra of PbS-PbTe SQS exhibit dynamic instabilities of S ions that corroborate reports of low-T ferroelectriclike phase transitions in solid solutions of PbS and PbTe, which are not present in either of the constituent compounds. We use our calculated vibrational spectra to obtain phase transition temperatures, which are in qualitative agreement with experimental results for PbTe-rich alloys, as well as to predict the existence of a low-T displacive phase transition in PbS-rich PbS-PbTe, which has not yet been experimentally investigated.

Substitutional carbon doping of free-standing and Ru-supported BN sheets: a first-principles study

NASA Astrophysics Data System (ADS)

Berseneva, N.; Komsa, H.-P.; Vierimaa, V.; Björkman, T.; Fan, Z.; Harju, A.; Todorović, M.; Krasheninnikov, A. V.; Nieminen, R. M.

2017-10-01

The development of spatially homogeneous mixed structures with boron (B), nitrogen (N) and carbon (C) atoms arranged in a honeycomb lattice is highly desirable, as they open the possibility of creating stable two-dimensional materials with tunable band gaps. However, at least in the free-standing form, the mixed BCN system is energetically driven towards phase segregation to graphene and hexagonal BN. It is possible to overcome the segregation when BCN material is grown on a particular metal substrate, for example Ru(0 0 0 1), but the stabilization mechanism is still unknown. With the use of density-functional theory we study the energetics of BN/Ru slabs, with different types of configurations of C substitutional defects introduced to the h-BN overlayer. The results are compared to the energetics of free-standing BCN materials. We found that the substrate facilitates the C substitution process in the h-BN overlayer. Thus, more homogeneous BCN material can be grown, overcoming the segregation into graphene and h-BN. In addition, we investigate the electronic and transport gaps in free-standing BCN structures, and assess their mechanical properties and stability. The band gap in mixed BCN free-standing material depends on the concentration of the constituent elements and ranges from zero in pristine graphene to nearly 5 eV in free-standing h-BN. This makes BCN attractive for application in modern electronics.

Method for producing nanocrystalline multicomponent and multiphase materials

DOEpatents

Eastman, J.A.; Rittner, M.N.; Youngdahl, C.J.; Weertman, J.R.

1998-03-17

A process for producing multi-component and multiphase nanophase materials is provided wherein a plurality of elements are vaporized in a controlled atmosphere, so as to facilitate thorough mixing, and then condensing and consolidating the elements. The invention also provides for a multicomponent and multiphase nanocrystalline material of specified elemental and phase composition having component grain sizes of between approximately 1 nm and 100 nm. This material is a single element in combination with a binary compound. In more specific embodiments, the single element in this material can be a transition metal element, a non-transition metal element, a semiconductor, or a semi-metal, and the binary compound in this material can be an intermetallic, an oxide, a nitride, a hydride, a chloride, or other compound. 6 figs.

Ceramic-glass-ceramic seal by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1983-10-04

A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

Ceramic-glass-ceramic seal by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1985-01-01

A method for producing a ceramic-glass-ceramic seal by microwaving, mixes a slurry of glass sealing material and coupling agent and applies same to ceramic workpieces. The slurry and workpieces are placed together, insulated and then microwaved at a power, time and frequency sufficient to cause a liquid phase reaction in the slurry. The reaction of the glass sealing material forms a chemically different seal than that which would be formed by conventional heating because it is formed by a diffusion rather than by wetting of the reactants.

Nonisovalent Si-III-V and Si-II-VI alloys: Covalent, ionic, and mixed phases

NASA Astrophysics Data System (ADS)

Kang, Joongoo; Park, Ji-Sang; Stradins, Pauls; Wei, Su-Huai

2017-07-01

Nonequilibrium growth of Si-III-V or Si-II-VI alloys is a promising approach to obtaining optically more active Si-based materials. We propose a new class of nonisovalent S i2AlP (or S i2ZnS ) alloys in which the Al-P (or Zn-S) atomic chains are as densely packed as possible in the host Si matrix. As a hybrid of the lattice-matched parent phases, S i2AlP (or S i2ZnS ) provides an ideal material system with tunable local chemical orders around Si atoms within the same composition and structural motif. Here, using first-principles hybrid functional calculations, we discuss how the local chemical orders affect the electronic and optical properties of the nonisovalent alloys.

[Characteristics of electroosmotic flow in open-tubular capillary electrochromatography with magnetic nanoparticle coating as mixed-mode stationary phase].

PubMed

Qin, Sasa; Zhou, Chaoran; Zhu, Yaxian; Ren, Zhiyu; Zhang, Lingyi; Fu, Honggang; Zhang, Weibing

2011-09-01

A novel open-tubular capillary electrochromatography (OT-CEC) column with magnetic nanoparticle coating as mixed-mode stationary phase was prepared. The mixed-mode stationary phases were obtained by mixing C18 and amino modified magnetic nanoparticles with different ratios. The mixed modified magnetic nanoparticles as stationary phase were introduced into the capillary by using external magnetic force. The magnetic nanoparticle coating can be easily regenerated by removing the external magnetic field, and applied to other separation modes. The characteristics of electroosmotic flow (EOF) were theoretically investigated through the effect of physicochemical properties of different stationary phases on EOF. The experiment was conducted under different ratios of mixed-mode stationary phases and coating lengths, and it was verified that the theoretical conclusions accorded with the experimental results. It was shown that the EOF can be easily adjusted by changing the ratio of stationary phases or the number of permanent magnets.

Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone

PubMed Central

Kikhtyanin, Oleg; Čapek, Libor; Tišler, Zdeněk; Velvarská, Romana; Panasewicz, Adriana; Diblíková, Petra; Kubička, David

2018-01-01

MgGa layered double hydroxides (Mg/Ga = 2–4) were synthesized and used for the preparation of MgGa mixed oxides and reconstructed hydrotalcites. The properties of the prepared materials were examined by physico-chemical methods (XRD, TGA, NH3-TPD, CO2-TPD, SEM, and DRIFT) and tested in aldol condensation of furfural and acetone. The as-prepared phase-pure MgGa samples possessed hydrotalcite structure, and their calcination resulted in mixed oxides with MgO structure with a small admixture phase characterized by a reflection at 2θ ≈ 36.0°. The interaction of MgGa mixed oxides with pure water resulted in reconstruction of the HTC structure already after 15 s of the rehydration with maximum crystallinity achieved after 60 s. TGA-MS experiments proved a substantial decrease in carbonates in all rehydrated samples compared with their as-prepared counterparts. This allowed suggesting presence of interlayer hydroxyls in the samples. Acido-basic properties of MgGa mixed oxides determined by TPD technique did not correlate with Mg/Ga ratio which was explained by the specific distribution of Ga atoms on the external surface of the samples. CO2-TPD method was also used to evaluate the basic properties of the reconstructed MgGa samples. In these experiments, an intensive peak at T = 450°C on CO2-TPD curve was attributed to the decomposition of carbonates newly formed by CO2 interaction with interlayer carbonates rather than to CO2 desorption from basic sites. Accordingly, CO2-TPD method quantitatively characterized the interlayer hydroxyls only indirectly. Furfural conversion on reconstructed MgGa materials was much larger compared with MgGa mixed oxides confirming that Brønsted basic sites in MgGa catalysts, like MgAl catalysts, were active in the reaction. Mg/Ga ratio in mixed oxides influenced product selectivity which was explained by the difference in textural properties of the samples. In contrast, Mg/Ga ratio in reconstructed catalysts had practically no effect on the composition of reaction products suggesting that the basic sites in these catalysts acted similarly in aldol condensation of acetone with furfural. It was concluded that the properties of MgGa samples resembled in a great extent those of MgAl hydrotalcite-based materials and demonstrated their potential as catalysts for base-catalyzed reactions. PMID:29881721

Physico-Chemical Properties of MgGa Mixed Oxides and Reconstructed Layered Double Hydroxides and Their Performance in Aldol Condensation of Furfural and Acetone.

PubMed

Kikhtyanin, Oleg; Čapek, Libor; Tišler, Zdeněk; Velvarská, Romana; Panasewicz, Adriana; Diblíková, Petra; Kubička, David

2018-01-01

MgGa layered double hydroxides (Mg/Ga = 2-4) were synthesized and used for the preparation of MgGa mixed oxides and reconstructed hydrotalcites. The properties of the prepared materials were examined by physico-chemical methods (XRD, TGA, NH 3 -TPD, CO 2 -TPD, SEM, and DRIFT) and tested in aldol condensation of furfural and acetone. The as-prepared phase-pure MgGa samples possessed hydrotalcite structure, and their calcination resulted in mixed oxides with MgO structure with a small admixture phase characterized by a reflection at 2θ ≈ 36.0°. The interaction of MgGa mixed oxides with pure water resulted in reconstruction of the HTC structure already after 15 s of the rehydration with maximum crystallinity achieved after 60 s. TGA-MS experiments proved a substantial decrease in carbonates in all rehydrated samples compared with their as-prepared counterparts. This allowed suggesting presence of interlayer hydroxyls in the samples. Acido-basic properties of MgGa mixed oxides determined by TPD technique did not correlate with Mg/Ga ratio which was explained by the specific distribution of Ga atoms on the external surface of the samples. CO 2 -TPD method was also used to evaluate the basic properties of the reconstructed MgGa samples. In these experiments, an intensive peak at T = 450°C on CO 2 -TPD curve was attributed to the decomposition of carbonates newly formed by CO 2 interaction with interlayer carbonates rather than to CO 2 desorption from basic sites. Accordingly, CO 2 -TPD method quantitatively characterized the interlayer hydroxyls only indirectly. Furfural conversion on reconstructed MgGa materials was much larger compared with MgGa mixed oxides confirming that Brønsted basic sites in MgGa catalysts, like MgAl catalysts, were active in the reaction. Mg/Ga ratio in mixed oxides influenced product selectivity which was explained by the difference in textural properties of the samples. In contrast, Mg/Ga ratio in reconstructed catalysts had practically no effect on the composition of reaction products suggesting that the basic sites in these catalysts acted similarly in aldol condensation of acetone with furfural. It was concluded that the properties of MgGa samples resembled in a great extent those of MgAl hydrotalcite-based materials and demonstrated their potential as catalysts for base-catalyzed reactions.

Physico-chemical properties of MgGa mixed oxides and reconstructed layered double hydroxides and their performance in aldol condensation of furfural and acetone

NASA Astrophysics Data System (ADS)

Kikhtyanin, Oleg; Čapek, Libor; Tišler, Zdeněk; Velvarská, Romana; Panasewicz, Adriana; Diblíková, Petra; Kubička, David

2018-05-01

MgGa layered double hydroxides (Mg/Ga=2-4) were synthesized and used for the preparation of MgGa mixed oxides and reconstructed hydrotalcites. The properties of the prepared materials were examined by physico-chemical methods (XRD, TGA, NH3-TPD, CO2-TPD, SEM and DRIFT) and tested in aldol condensation of furfural and acetone. The as-prepared phase-pure MgGa samples possessed hydrotalcite structure, and their calcination resulted in mixed oxides with MgO structure with a small admixture phase characterized by a reflection at 2θ ≈ 36.0°. The interaction of MgGa mixed oxides with pure water resulted in reconstruction of the HTC structure already after 15 s of the rehydration with maximum crystallinity achieved after 60 s. TGA-MS experiments proved a substantial decrease in carbonates in all rehydrated samples compared with their as-prepared counterparts. This allowed suggesting presence of interlayer hydroxyls in the samples. Acido-basic properties of MgGa mixed oxides determined by TPD technique did not correlate with Mg/Ga ratio which was explained by the specific distribution of Ga atoms on the external surface of the samples. CO2-TPD method was also used to evaluate the basic properties of the reconstructed MgGa samples. In these experiments, an intensive peak at T=450 °C on CO2-TPD curve was attributed to the decomposition of carbonates newly formed by CO2 interaction with interlayer carbonates rather than to CO2 desorption from basic sites. Accordingly, CO2-TPD method quantitatively characterized the interlayer hydroxyls only indirectly. Furfural conversion on reconstructed MgGa materials was much larger compared with MgGa mixed oxides confirming that Brønsted basic sites in MgGa catalysts, like MgAl catalysts, were active in the reaction. Mg/Ga ratio in mixed oxides influenced product selectivity which was explained by the difference in textural properties of the samples. In contrast, Mg/Ga ratio in reconstructed catalysts had practically no effect on the composition of reaction products suggesting that the basic sites in these catalysts acted similarly in aldol condensation of acetone with furfural. It was concluded that the properties of MgGa samples resembled in a great extent those of MgAl hydrotalcite-based materials and demonstrated their potential as catalysts for base-catalyzed reactions.

Effect of nanoparticles on heat capacity of nanofluids based on molten salts as PCM for thermal energy storage

PubMed Central

2013-01-01

In this study, different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (selected as phase change material) with nanoparticles using the direct-synthesis method. The thermal properties of the nanofluids obtained were investigated. These nanofluids can be used in concentrating solar plants with a reduction of storage material if an improvement in the specific heat is achieved. The base salt mixture was a NaNO3-KNO3 (60:40 ratio) binary salt. The nanoparticles used were silica (SiO2), alumina (Al2O3), titania (TiO2), and a mix of silica-alumina (SiO2-Al2O3). Three weight fractions were evaluated: 0.5, 1.0, and 1.5 wt.%. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements on thermophysical properties were performed by differential scanning calorimetry analysis and the dispersion of the nanoparticles was analyzed by scanning electron microscopy (SEM). The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of 15% to 57% in the solid phase and of 1% to 22% in the liquid phase. In particular, this research shows that the addition of silica-alumina nanoparticles has a significant potential for enhancing the thermal storage characteristics of the NaNO3-KNO3 binary salt. These results deviated from the predictions of the theoretical model used. SEM suggests a greater interaction between these nanoparticles and the salt. PMID:24168168

Thermodynamic interpretation of reactive processes in Ni-Al nanolayers from atomistic simulations

NASA Astrophysics Data System (ADS)

Sandoval, Luis; Campbell, Geoffrey H.; Marian, Jaime

2014-03-01

Metals that can form intermetallic compounds by exothermic reactions constitute a class of reactive materials with multiple applications. Ni-Al laminates of thin alternating layers are being considered as model nanometric metallic multilayers for studying various reaction processes. However, the reaction kinetics at short timescales after mixing are not entirely understood. In this work, we calculate the free energies of Ni-Al alloys as a function of composition and temperature for different solid phases using thermodynamic integration based on state-of-the-art interatomic potentials. We use this information to interpret molecular dynamics (MD) simulations of bilayer systems at 800 K and zero pressure, both in isothermal and isenthalpic conditions. We find that a disordered phase always forms upon mixing as a precursor to a more stable nano crystalline B2 phase. We construe the reactions observed in terms of thermodynamic trajectories governed by the state variables computed. Simulated times of up to 30 ns were achieved, which provides a window to phenomena not previously observed in MD simulations. Our results provide insight into the early experimental reaction timescales and suggest that the path (segregated reactants) → (disordered phase) → (B2 structure) is always realized irrespective of the imposed boundary conditions.

Phase and birefringence aberration correction

DOEpatents

Bowers, Mark; Hankla, Allen

1996-01-01

A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

Phase and birefringence aberration correction

DOEpatents

Bowers, M.; Hankla, A.

1996-07-09

A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

The Investigation of Chlorate/Iron-Phase Mixtures as a Possible Source of Oxygen and Chlorine Detected by the Sample Analysis at Mars (SAM) Instrument in Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Clark, J.; Sutter, B.; Morris, R. V.; Archer, P. D.; Ming, D. W.; Niles, P.; Mahaffy, P.; Navarro-Gonzalez, R.

2016-01-01

The Sample Analysis at Mars (SAM) instrument on board the Curiosity Rover has detected oxygen and HCl gas releases from all analyzed Gale Crater sediments. The presence of perchlorate ClO4(sup-) and/or chlorates ClO3(sup-) are potential sources of the aforementioned O2 releases. The detections of O2 and HCl gas releases and chlorinated hydrocarbons by SAM coupled with the detection of perchlorates by Phoenix Lander's 2008 Wet Chemistry Laboratory all suggest that perchlorates, and possibly chorates, may be present in the Gale Crater sediments. Previous laboratory studies have attempted to replicate these O2 releases by heating perchlorates and chlorates in instruments operated similarly to those in the SAM instrument. Early studies found that pure perchlorates release O2 at temperatures higher than those observed in SAM data. Subsequently, studies were done to test the effects of mixing iron-phase minerals, analogous to those detected on Mars by ChemMin, with perchlorates. The iron in these minerals acts as a catalyst and causes O2 to be released from the perchlorate at a lower temperature. These studies found that perchlorate solutions mixed with either Hawaii palagonite or ferrihydrite produce O2 releases at temperatures similar to the Rocknest (RN) windblown deposit and the John Klein (JK) drill sample from the Sheepbed mudstone. The study also determined that perchlorate mixtures with magnetite, hematite, fayalite-magnetite, ilmentite, and pyrrhotite produce O2 releases at temperatures similar to the Confidence Hills (CH) drill sample from the Murray mudstone. Oxygen re-leases from pure chlorates were recently compared with the SAM data. Laboratory analyses determined that Ca-chlorate produces O2 and HCl peaks that are similar to those detected in RN and JK materials. Currently, no perchlorate/chlorate mixture with iron-phase minerals can explain the O2 releases from either the Cumberland (CB) drill sample from the Sheepbed mudstone or Windjana (WJ) drill sample from the Kimberly sandstone. Mixtures of chlorate solutions with iron-phase minerals may produce O2 peaks at temperatures that match those from CB and WJ materials. The goal of this work is to determine if heating chlorate solutions mixed with iron-phase minerals will produce O2 and HCl peak temperatures similar to O2 and HCl peak temperatures of sediments analyzed by SAM, particularly the WJ and CB materials.

Degradation studies of transparent conductive electrodes on electroactive poly(vinylidene fluoride) for uric acid measurements

NASA Astrophysics Data System (ADS)

Cardoso, Vanessa F.; Martins, Pedro; Botelho, Gabriela; Rebouta, Luis; Lanceros-Méndez, Senentxu; Minas, Graca

2010-08-01

Biochemical analysis of physiological fluids using, for example, lab-on-a-chip devices requires accurate mixing of two or more fluids. This mixing can be assisted by acoustic microagitation using a piezoelectric material, such as the β-phase of poly(vinylidene fluoride) (β-PVDF). If the analysis is performed using optical absorption spectroscopy and β-PVDF is located in the optical path, the material and its conductive electrodes must be transparent. Moreover, if, to improve the transmission of the ultrasonic waves to the fluids, the piezoelectric transducer is placed inside the fluidic structures, its degradation must be assessed. In this paper, we report on the degradation properties of transparent conductive oxides, namely, indium tin oxide (ITO) and aluminum-doped zinc oxide, when they are used as electrodes for providing acoustic microagitation. The latter promotes mixing of chemicals involved in the measurement of uric acid concentration in physiological fluids. The results are compared with those for aluminum electrodes. We find that β-PVDF samples with ITO electrodes do not degrade either with or without acoustic microagitation.

Numerical Simulation of Rocket Exhaust Interaction with Lunar Soil

NASA Technical Reports Server (NTRS)

Liever, Peter; Tosh, Abhijit; Curtis, Jennifer

2012-01-01

This technology development originated from the need to assess the debris threat resulting from soil material erosion induced by landing spacecraft rocket plume impingement on extraterrestrial planetary surfaces. The impact of soil debris was observed to be highly detrimental during NASA s Apollo lunar missions and will pose a threat for any future landings on the Moon, Mars, and other exploration targets. The innovation developed under this program provides a simulation tool that combines modeling of the diverse disciplines of rocket plume impingement gas dynamics, granular soil material liberation, and soil debris particle kinetics into one unified simulation system. The Unified Flow Solver (UFS) developed by CFDRC enabled the efficient, seamless simulation of mixed continuum and rarefied rocket plume flow utilizing a novel direct numerical simulation technique of the Boltzmann gas dynamics equation. The characteristics of the soil granular material response and modeling of the erosion and liberation processes were enabled through novel first principle-based granular mechanics models developed by the University of Florida specifically for the highly irregularly shaped and cohesive lunar regolith material. These tools were integrated into a unique simulation system that accounts for all relevant physics aspects: (1) Modeling of spacecraft rocket plume impingement flow under lunar vacuum environment resulting in a mixed continuum and rarefied flow; (2) Modeling of lunar soil characteristics to capture soil-specific effects of particle size and shape composition, soil layer cohesion and granular flow physics; and (3) Accurate tracking of soil-borne debris particles beginning with aerodynamically driven motion inside the plume to purely ballistic motion in lunar far field conditions. In the earlier project phase of this innovation, the capabilities of the UFS for mixed continuum and rarefied flow situations were validated and demonstrated for lunar lander rocket plume flow impingement under lunar vacuum conditions. Applications and improvements to the granular flow simulation tools contributed by the University of Florida were tested against Earth environment experimental results. Requirements for developing, validating, and demonstrating this solution environment were clearly identified, and an effective second phase execution plan was devised. In this phase, the physics models were refined and fully integrated into a production-oriented simulation tool set. Three-dimensional simulations of Apollo Lunar Excursion Module (LEM) and Altair landers (including full-scale lander geometry) established the practical applicability of the UFS simulation approach and its advanced performance level for large-scale realistic problems.

Toward multiscale modelings of grain-fluid systems

NASA Astrophysics Data System (ADS)

Chareyre, Bruno; Yuan, Chao; Montella, Eduard P.; Salager, Simon

2017-06-01

Computationally efficient methods have been developed for simulating partially saturated granular materials in the pendular regime. In contrast, one hardly avoid expensive direct resolutions of 2-phase fluid dynamics problem for mixed pendular-funicular situations or even saturated regimes. Following previous developments for single-phase flow, a pore-network approach of the coupling problems is described. The geometry and movements of phases and interfaces are described on the basis of a tetrahedrization of the pore space, introducing elementary objects such as bridge, meniscus, pore body and pore throat, together with local rules of evolution. As firmly established local rules are still missing on some aspects (entry capillary pressure and pore-scale pressure-saturation relations, forces on the grains, or kinetics of transfers in mixed situations) a multi-scale numerical framework is introduced, enhancing the pore-network approach with the help of direct simulations. Small subsets of a granular system are extracted, in which multiphase scenario are solved using the Lattice-Boltzman method (LBM). In turns, a global problem is assembled and solved at the network scale, as illustrated by a simulated primary drainage.

Detecting Nanophase Weathering Products with CheMin: Reference Intensity Ratios of Allophane, Aluminosilicate Gel, and Ferrihydrite

NASA Technical Reports Server (NTRS)

Rampe, E. B.; Bish, D. L.; Chipera, S. J.; Morris, R. V.; Achilles, C. N.; Ming, D W.; Blake, D. F.; Anderson, R. C.; Bristow, T. F.; Crisp, A.;

Study of in-situ formation of Fe-Mn-Si shape memory alloy welding seam by laser welding with filler powder

NASA Astrophysics Data System (ADS)

Ju, Heng; Lin, Chengxin; Liu, Zhijie; Zhang, Jiaqi

2018-08-01

To reduce the residual stresses and improve the mechanical properties of laser weldments, produced with the restrained mixing uniform design method, a Fe-Mn-Si shape memory alloy (SMA) welding seam was formed inside the 304 stainless steel by laser welding with powder filling. The mass fraction, shape memory effect, and phase composition of the welding seam was measured by SEM-EDS (photometric analyser), bending recovery method, and XRD, respectively. An optical microscope was used to observe the microstructure of the Fe-Mn-Si SMA welding seam by solid solution and pre-deformation treatment. Meanwhile, the mechanical properties (residual stress distribution, tensile strength, microhardness and fatigue strength) of the laser welded specimen with an Fe-Mn-Si SMA welding seam (experimental material) and a 304 stainless steel welding seam (contrast material) were measured by a tensile testing machine hole drilling method and full cycle bending fatigue test. The results show that Fe15Mn5Si12Cr6Ni SMA welding seam was formed in situ with shape memory effect and stress-induced γ → ε martensite phase transformation characteristic. The residual stress of the experimental material is lower than that of the contrast material. The former has larger tensile strength, longer elongation and higher microhardness than the latter has. The experimental material and contrast material possess 249 and 136 bending fatigue cycles at the strain of 6%, respectively. The mechanisms by which mechanical properties of the experimental material are strengthened includes (1) release of the residual stress inside the Fe-Mn-Si SMA welding seam due to the stress-induced γ → ε martensite phase transformation and (2) energy absorption and plastic slip restraint due to the deformations in martensite and reverse phase transformation.

Characteristics of Nano-emulsion for Cold Thermal Storage

NASA Astrophysics Data System (ADS)

Fumoto, Koji; Kawaji, Masahiro; Kawanami, Tsuyoshi

Phase change emulsion (PCE) is novel kind of heat storage and heat transfer fluids. It has characteristics as follows; greater apparent specific heat and higher heat transfer abilities in the phase change temperature range than conventional single phase heat transfer fluid. In this paper, a phase change emulsion, which has droplet diameter distribution of nanometer, were prepared. The Nano-emulsion was formed by low energy emulsification methods, as known the phase inversion temperature (PIT) method. Physical properties, such as viscosity, diameter and its distribution of emulsion were investigated. Especially, the relationships between preparation method and the concentration of surfactant have been discussed in detail. The results show that the viscosity of the Nano-emulsion is lower than the micro-emulsion, which was made by same mixing ratio of surfactant and concentration of phase change material. In addition, the Nano-emulsion clarified that stability was higher than microemulsions.

Microstructure, mixing rules and interfacial behavior in high k barium titanate epoxy composite

NASA Astrophysics Data System (ADS)

Shi, Yitong (Thomas)

2001-07-01

In this thesis, we have demonstrated the importance of two issues in BaTiO3/epoxy composites. They are (1) the miscibility of a particle blend in organic vehicle, i.e. the capability of particles with different particle sizes to mix at the particle level, and (2) the ceramic/polymer interface as a role in determining the effective dielectric constant. The epoxy matrix between the BaTiO3 particles is not homogeneous and has to be modeled as a two-layer structure. The inhomogeneity causes not only failure of the existing mixing rules but also the particle size dependence of the effective dielectric constant. Since the interfacial behavior is determined by the materials chemistry, the effective dielectric properties experimentally demonstrate strong dependence on the materials selection and processing. If BaTiO3 particles in liquid epoxy resin has a bimodal particle size distribution, the smaller particles do not experimentally fit into the interstitial spaces between the larger spheres in an organic vehicle. ESEM observations indicated that the large particles separated from the small ones. Depending on the paste formula, the particle separation led to either a layer-like or cluster-like microstructure. The mixing free energy of blending smaller particles with larger particles explains the observed phenomena and suggests general criteria for particle miscibility. Whenever the mixing free energy is negative and the mixing free energy curve is convex, the particle blend remains in a random particle distribution. Otherwise, the particles separate into a larger-particle rich "phase" and a smaller-particle rich "phase". A random particle distribution may be the largest degree of mixing we can achieve in an organic vehicle. If there is no specific interaction between the small particles and the large particles, there is no thermodynamic driving force for small particles to fill preferentially into the interstitial spaces between the large spheres. The Hamaker constant H significantly influences the miscibility of a particle blend. An increase in Hamaker constant H causes not only greater driving force for a particle blend to separate but also a more narrowed convex shape---the mixing window. At a specific composition, a particle blend separates in one vehicle but may remain in a random distribution in another vehicle if the later vehicle has significantly reduced the Hamaker constant H.

Using SANS with Contrast-Matched Lipid Bicontinuous Cubic Phases To Determine the Location of Encapsulated Peptides, Proteins, and Other Biomolecules.

PubMed

van 't Hag, Leonie; de Campo, Liliana; Garvey, Christopher J; Feast, George C; Leung, Anna E; Yepuri, Nageshwar Rao; Knott, Robert; Greaves, Tamar L; Tran, Nhiem; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

2016-07-21

An understanding of the location of peptides, proteins, and other biomolecules within the bicontinuous cubic phase is crucial for understanding and evolving biological and biomedical applications of these hybrid biomolecule-lipid materials, including during in meso crystallization and drug delivery. While theoretical modeling has indicated that proteins and additive lipids might phase separate locally and adopt a preferred location in the cubic phase, this has never been experimentally confirmed. We have demonstrated that perfectly contrast-matched cubic phases in D2O can be studied using small-angle neutron scattering by mixing fully deuterated and hydrogenated lipid at an appropriate ratio. The model transmembrane peptide WALP21 showed no preferential location in the membrane of the diamond cubic phase of phytanoyl monoethanolamide and was not incorporated in the gyroid cubic phase. While deuteration had a small effect on the phase behavior of the cubic phase forming lipids, the changes did not significantly affect our results.

Global geologic map of Ganymede

USGS Publications Warehouse

Collins, Geoffrey C.; Patterson, G. Wesley; Head, James W.; Pappalardo, Robert T.; Prockter, Louise M.; Lucchitta, Baerbel K.; Kay, Johnathan P.

2014-01-01

Ganymede is the largest satellite of Jupiter, and its icy surface has been formed through a variety of impact cratering, tectonic, and possibly cryovolcanic processes. The history of Ganymede can be divided into three distinct phases: an early phase dominated by impact cratering and mixing of non-ice materials in the icy crust, a phase in the middle of its history marked by great tectonic upheaval, and a late quiescent phase characterized by a gradual drop in heat flow and further impact cratering. Images of Ganymede suitable for geologic mapping were collected during the flybys of Voyager 1 and Voyager 2 (1979), as well as during the Galileo Mission in orbit around Jupiter (1995–2003). This map represents a synthesis of our understanding of Ganymede geology after the conclusion of the Galileo Mission. We summarize the properties of the imaging dataset used to construct the map, previously published maps of Ganymede, our own mapping rationale, and the geologic history of Ganymede. Additional details on these topics, along with detailed descriptions of the type localities for the material units, may be found in the companion paper to this map (Patterson and others, 2010).

Processing of Mixed Oxide Superconductors

DTIC Science & Technology

1990-07-01

rapid changes world wide a major research centre on high Tc superconductors was awarded to Cambridge which involved moving the work and people to a...reports and paper is in the appendices. Separation Ceramic superconductors tend to be mixtures of phases, especially when first discovered. It would...properties of the superconducting state will in principle allow superconducting material to be levitated from the non superconductor and several designs

Asymptotic Slavery in the Copper Oxide High Temperature Superconductors

NASA Astrophysics Data System (ADS)

Phillips, Philip

2004-05-01

Vast progress in theoretical solid state physics has been made by constructing models which mimic the low-energy properties of solids. Essential to the success of this program is the separability of the high and low energy degrees of freedom. While it is hoped that a high energy reduction can be made to solve the problem of high temperature superconductivity in the copper oxide materials, I will show that no consistent theory is possible if the high energy scale is removed. At the heart of the problem is the mixing of all energy scales (that is, UV-IR mixing) in the copper-oxide materials. Optical experiments demonstrate that the number of low-energy degrees of freedom is derived from a high energy scale. The implications of the inseparability of the high and low energy degrees of freedom on the phase diagram of the cuprates is discussed.

Comparative study between structural and electrical properties of geopolymers applied to a green concrete

NASA Astrophysics Data System (ADS)

Montaño, A. M.; González, C. P.; Pérez, J.; Royero, C.; Sandoval, D.; Gutiérrez, J.

2013-11-01

This work shows a comparative analysis of geopolymers obtained by alkaline activation of two aluminosilicates: bentonite and metakaolin. With the goal of to replace some cement percentage, both aluminosilicates were added in several proportions (10, 20 and 30%) to concrete mixes. Portland Type I cement was used to prepare the reference concrete (without geopolymer). X-ray diffraction of geopolymers allowed to find new crystallographic phases that was not present in precursor's minerals. To evaluate mechanical properties of concrete prepared with geopolymers, test tubes with 7, 14, 28 and 90 days as setting time were used. Chemical resistance and Electrical impedance of concrete mixes were also measured. Results shows that cementitious material obtained from metakaolin exhibit the best compressive strength. On the other hand, those materials derived from bentonite, have a high electrical resistance so that, they protected reinforced concrete better that Portland does.

Physics of frequency-modulated comb generation in quantum-well diode lasers

NASA Astrophysics Data System (ADS)

Dong, Mark; Cundiff, Steven T.; Winful, Herbert G.

2018-05-01

We investigate the physical origin of frequency-modulated combs generated from single-section semiconductor diode lasers based on quantum wells, isolating the essential physics necessary for comb generation. We find that the two effects necessary for comb generation—spatial hole burning (leading to multimode operation) and four-wave mixing (leading to phase locking)—are indeed present in some quantum-well systems. The physics of comb generation in quantum wells is similar to that in quantum dot and quantum cascade lasers. We discuss the nature of the spectral phase and some important material parameters of these diode lasers.

Functional organic materials based on polymerized liquid-crystal monomers: supramolecular hydrogen-bonded systems.

PubMed

Broer, Dirk J; Bastiaansen, Cees M W; Debije, Michael G; Schenning, Albertus P H J

2012-07-16

Functional organic materials are of great interest for a variety of applications. To obtain precise functional properties, well-defined hierarchically ordered supramolecular materials are crucial. The self-assembly of liquid crystals has proven to be an extremely useful tool in the development of well-defined nanostructured materials. We have chosen the illustrative example of photopolymerizable hydrogen-bonding mesogens to show that a wide variety of functional materials can be made from a relatively simple set of building blocks. Upon mixing these compounds with other reactive mesogens, nematic, chiral nematic, and smectic or columnar liquid-crystalline phases can be formed that can be applied as actuators, sensors and responsive reflectors, and nanoporous membranes, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox-responsive self-healing materials formed from host–guest polymers

PubMed Central

Nakahata, Masaki; Takashima, Yoshinori; Yamaguchi, Hiroyasu; Harada, Akira

2011-01-01

Expanding the useful lifespan of materials is becoming highly desirable, and self-healing and self-repairing materials may become valuable commodities. The formation of supramolecular materials through host–guest interactions is a powerful method to create non-conventional materials. Here we report the formation of supramolecular hydrogels and their redox-responsive and self-healing properties due to host–guest interactions. We employ cyclodextrin (CD) as a host molecule because it is environmentally benign and has diverse applications. A transparent supramolecular hydrogel quickly forms upon mixing poly(acrylic acid) (pAA) possessing β-CD as a host polymer with pAA possessing ferrocene as a guest polymer. Redox stimuli induce a sol−gel phase transition in the supramolecular hydrogel and can control self-healing properties such as re-adhesion between cut surfaces. PMID:22027591

Self-assembly of nanocomposite materials

DOEpatents

Brinker, C. Jeffrey; Sellinger, Alan; Lu, Yunfeng

2001-01-01

A method of making a nanocomposite self-assembly is provided where at least one hydrophilic compound, at least one hydrophobic compound, and at least one amphiphilic surfactant are mixed in an aqueous solvent with the solvent subsequently evaporated to form a self-assembled liquid crystalline mesophase material. Upon polymerization of the hydrophilic and hydrophobic compounds, a robust nanocomposite self-assembled material is formed. Importantly, in the reaction mixture, the amphiphilic surfactant has an initial concentration below the critical micelle concentration to allow formation of the liquid-phase micellar mesophase material. A variety of nanocomposite structures can be formed, depending upon the solvent evaporazation process, including layered mesophases, tubular mesophases, and a hierarchical composite coating composed of an isotropic worm-like micellar overlayer bonded to an oriented, nanolaminated underlayer.

49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 2 2012-10-01 2012-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive) materials...

49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive) materials...

49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive) materials...

49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive) materials...

49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 2 2014-10-01 2014-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive) materials...

Extrusion-mixing compared with hand-mixing of polyether impression materials?

PubMed

McMahon, Caroline; Kinsella, Daniel; Fleming, Garry J P

2010-12-01

The hypotheses tested were two-fold (a) whether altering the base:catalyst ratio influences working time, elastic recovery and strain in compression properties of a hand-mixed polyether impression material and (b) whether an extrusion-mixed polyether impression material would have a significant advantage over a hand-mixed polyether impression material mixed to the optimum base:catalyst ratio. The polyether was hand-mixed at the optimum (manufacturers recommended) base:catalyst ratios (7:1) and further groups were made by increasing or decreasing the catalyst length by 25%. Additionally specimens were also made from an extrusion-mixed polyether impression material and compared with the optimum hand-mixed base:catalyst ratio. A penetrometer assembly was used to measure the working time (n=5). Five cylindrical specimens for each hand-mixed and extrusion mixed group investigated were employed for elastic recovery and strain in compression testing. Hand-mixing polyether impression materials with 25% more catalyst than that recommended significantly decreased the working time while hand-mixing with 25% less catalyst than that recommended significantly increased the strain in compression. The extrusion-mixed polyether impression material provided similar working time, elastic recovery and strain in compression to the hand-mixed polyether mixed at the optimum base:catalyst ratio.

Physical State and Distribution of Materials at the Surface of Pluto from New Horizons LEISA Imaging Spectrometer

NASA Technical Reports Server (NTRS)

Schmitt, B.; Philippe, S.; Grundy, W. M.; Reuter, D. C.; Cote, R.; Quirico, E.; Protopappa, S.; Young, L. A.; Binzel, R. P.; Cook, J. C.;

Physical state and distribution of materials at the surface of Pluto from New Horizons LEISA imaging spectrometer

NASA Astrophysics Data System (ADS)

Schmitt, B.; Philippe, S.; Grundy, W. M.; Reuter, D. C.; Côte, R.; Quirico, E.; Protopapa, S.; Young, L. A.; Binzel, R. P.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Howett, C. J. A.; Jennings, D. E.; Linscott, I. R.; Lunsford, A. W.; Olkin, C. B.; Parker, A. H.; Parker, J. Wm.; Singer, K. N.; Spencer, J. R.; Stansberry, J. A.; Stern, S. A.; Tsang, C. C. C.; Verbiscer, A. J.; Weaver, H. A.; New Horizons Science Team

2017-05-01

From Earth based observations Pluto is known to be the host of N2, CH4 and CO ices and also a dark red material. Very limited spatial distribution information is available from rotational visible and near-infrared spectral curves obtained from hemispheric measurements. In July 2015 the New Horizons spacecraft reached Pluto and its satellite system and recorded a large set of data. The LEISA spectro-imager of the RALPH instruments are dedicated to the study of the composition and physical state of the materials composing the surface. In this paper we report a study of the distribution and physical state of the ices and non-ice materials on Pluto's illuminated surface and their mode and degree of mixing. Principal Component analysis as well as various specific spectral indicators and correlation plots are used on the first set of 2 high resolution spectro-images from the LEISA instrument covering the whole illuminated face of Pluto at the time of the New Horizons encounter. Qualitative distribution maps have been obtained for the 4 main condensed molecules, N2, CH4, CO, H2O as well as for the visible-dark red material. Based on specific spectral indicators, using either the strength or the position of absorption bands, these 4 molecules are found to indicate the presence of 3 different types of ices: N2-rich:CH4:CO ices, CH4-rich(:CO:N2?) ices and H2O ice. The mixing lines between these ices and with the dark red material are studied using scatter plots between the various spectral indicators. CH4 is mixed at the molecular level with N2, most probably also with CO, thus forming a ternary molecular mixture that follows its phase diagram with low solubility limits. The occurrence of a N2-rich - CH4-rich ices mixing line associated with a progressive decrease of the CO/CH4 ratio tells us that a fractionation sublimation sequence transforms one type of ice to the other forming either a N2-rich - CH4-rich binary mixture at the surface or an upper CH4-rich ice crust that may hide the N2-rich ice below. The strong CH4-rich - H2O mixing line witnesses the subsequent sublimation of the CH4-rich ice lag left behind by the N2:CO sublimation (N spring-summer), or a direct condensation of CH4 ice on the cold H2O ice (S autumn). The weak mixing line between CH4-containing ices and the dark red material and the very sharp spatial transitions between these ices and this non-volatile material are probably due to thermal incompatibility. Finally the occurrence of a H2O ice - red material mixing line advocates for a spatial mixing of the red material covering H2O ice, with possibly a small amount intimately mixed in water ice. From this analysis of the different materials distribution and their relative mixing lines, H2O ice appears to be the substratum on which other ices condense or non-volatile organic material is deposited from the atmosphere. N2-rich ices seem to evolve to CH4-dominated ices, possibly still containing traces of CO and N2, as N2 and CO sublimate away. The spatial distribution of these materials is very complex. The high spatial definition of all these composition maps, as well as those at even higher resolution that will be soon available, will allow us to compare them with Pluto's geologic features observed by LORRI panchromatic and MVIC multispectral imagers to better understand the geophysical processes in action at the surface of this astonishingly active frozen world.

The role of ice nuclei recycling in the maintenance of cloud ice in Arctic mixed-phase stratocumulus

DOE PAGES

Solomon, Amy; Feingold, G.; Shupe, M. D.

2015-09-25

This study investigates the maintenance of cloud ice production in Arctic mixed-phase stratocumulus in large eddy simulations that include a prognostic ice nuclei (IN) formulation and a diurnal cycle. Balances derived from a mixed-layer model and phase analyses are used to provide insight into buffering mechanisms that maintain ice in these cloud systems. We find that, for the case under investigation, IN recycling through subcloud sublimation considerably prolongs ice production over a multi-day integration. This effective source of IN to the cloud dominates over mixing sources from above or below the cloud-driven mixed layer. Competing feedbacks between dynamical mixing andmore » recycling are found to slow the rate of ice lost from the mixed layer when a diurnal cycle is simulated. Furthermore, the results of this study have important implications for maintaining phase partitioning of cloud ice and liquid that determine the radiative forcing of Arctic mixed-phase clouds.« less

The role of ice nuclei recycling in the maintenance of cloud ice in Arctic mixed-phase stratocumulus

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

Solomon, Amy; Feingold, G.; Shupe, M. D.

This study investigates the maintenance of cloud ice production in Arctic mixed-phase stratocumulus in large eddy simulations that include a prognostic ice nuclei (IN) formulation and a diurnal cycle. Balances derived from a mixed-layer model and phase analyses are used to provide insight into buffering mechanisms that maintain ice in these cloud systems. We find that, for the case under investigation, IN recycling through subcloud sublimation considerably prolongs ice production over a multi-day integration. This effective source of IN to the cloud dominates over mixing sources from above or below the cloud-driven mixed layer. Competing feedbacks between dynamical mixing andmore » recycling are found to slow the rate of ice lost from the mixed layer when a diurnal cycle is simulated. Furthermore, the results of this study have important implications for maintaining phase partitioning of cloud ice and liquid that determine the radiative forcing of Arctic mixed-phase clouds.« less

Force-induced desorption of 3-star polymers: a self-avoiding walk model

NASA Astrophysics Data System (ADS)

Janse van Rensburg, E. J.; Whittington, S. G.

2018-05-01

We consider a simple cubic lattice self-avoiding walk model of 3-star polymers adsorbed at a surface and then desorbed by pulling with an externally applied force. We determine rigorously the free energy of the model in terms of properties of a self-avoiding walk, and show that the phase diagram includes four phases, namely a ballistic phase where the extension normal to the surface is linear in the length, an adsorbed phase and a mixed phase, in addition to the free phase where the model is neither adsorbed nor ballistic. In the adsorbed phase all three branches or arms of the star are adsorbed at the surface. In the ballistic phase two arms of the star are pulled into a ballistic phase, while the remaining arm is in a free phase. In the mixed phase two arms in the star are adsorbed while the third arm is ballistic. The phase boundaries separating the ballistic and mixed phases, and the adsorbed and mixed phases, are both first order phase transitions. The presence of the mixed phase is interesting because it does not occur for pulled, adsorbed self-avoiding walks. In an atomic force microscopy experiment it would appear as an additional phase transition as a function of force.

Sequential Introduction of Cations Deriving Large-Grain Csx FA1-x PbI3 Thin Film for Planar Hybrid Solar Cells: Insight into Phase-Segregation and Thermal-Healing Behavior.

PubMed

Huang, Jiahao; Xu, Pan; Liu, Jian; You, Xiao-Zeng

2017-03-01

Composition engineering of perovskite materials has been demonstrated to be important for high-performance solar cells. Recently, the energy favorable hybridization of formamidinium (FA) and cesium (Cs) in three dimension lead halide perovskites has been attracting increasing attention due to its potential benefit on durability. Herein, we reported a simple and effective method to produce phase-pure CsxFA1-xPbI3 thin film via sequential introduction of cations, in which the FA cation was introduced by interdiffusion annealing in the presence of N-methylimidazole (NMI). NMI was employed as an additive to slow down the crystallization and thus drive the formation of CsxFA1-xPbI3 with micrometer grain size, which probably facilitate the charge dissociation and transportation in photovoltaic devices. More importantly, composition dependent phase-segregation has been revealed and investigated for the first time during the phase-pure mixed-cation perovskites CsxFA1-xPbI3. The present findings demonstrated that suppressing phase-segregation of mixed-cation perovskites by meticulous composition engineering is significant for further development of efficient photovoltaics. It also suggested that phase-pure Cs0.15FA0.85PbI3 may be a promising candidate with superior phase-durability, which performed an efficiency over 16% in planar perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural and dynamical trends in alkali-metal silanides characterized by neutron-scattering methods

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

Tang, Wan Si; Dimitrievska, Mirjana; Chotard, Jean -Noel

Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH 3, where M = K, Rb, Cs, K 0.5Rb 0.5, K 0.5Cs 0.5, and Rb 0.5Cs 0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron vibrational spectroscopy (NVS), neutron-scattering fixed-window scans (FWSs), and quasielastic neutron scattering (QENS) measurements. Structural characterization showed that the mixed compounds exhibit disordered (α) and ordered (β) phases for temperatures above and below about 200–250 K, respectively, in agreement with their monoalkali correspondents. Vibrational and dynamical properties are strongly influenced by the cation environment; in particular, there is a redmore » shift in the band energies of the librational and bending modes with increasing lattice size as a result of changes in the bond lengths and force constants. Additionally, slightly broader spectral features are observed in the case of the mixed compounds, indicating the presence of structural disorder caused by the random distribution of the alkali-metal cations within the lattice. FWS measurements upon heating showed that there is a large increase in reorientational mobility as the systems go through the order–disorder (β–α) phase transition, and measurements upon cooling of the α-phase revealed the known strong hysteresis for reversion back to the β-phase. Interestingly, at a given temperature, among the different alkali silanide compounds, the relative reorientational mobilities of the SiH 3 – anions in the α- and β-phases tended to decrease and increase, respectively, with increasing alkali-metal mass. Lastly, this dynamical result might provide some insights concerning the enthalpy–entropy compensation effect previously observed for these potentially promising hydrogen storage materials.« less

Incoherent population mixing contributions to phase-modulation two-dimensional coherent excitation spectra

NASA Astrophysics Data System (ADS)

Grégoire, Pascal; Srimath Kandada, Ajay Ram; Vella, Eleonora; Tao, Chen; Leonelli, Richard; Silva, Carlos

2017-09-01

We present theoretical and experimental results showing the effects of incoherent population mixing on two-dimensional (2D) coherent excitation spectra that are measured via a time-integrated population and phase-sensitive detection. The technique uses four collinear ultrashort pulses and phase modulation to acquire two-dimensional spectra by isolating specific nonlinear contributions to the photoluminescence or photocurrent excitation signal. We demonstrate that an incoherent contribution to the measured line shape, arising from nonlinear population dynamics over the entire photoexcitation lifetime, generates a similar line shape to the expected 2D coherent spectra in condensed-phase systems. In those systems, photoexcitations are mobile such that inter-particle interactions are important on any time scale, including those long compared with the 2D coherent experiment. Measurements on a semicrystalline polymeric semiconductor film at low temperatures show that, in some conditions in which multi-exciton interactions are suppressed, the technique predominantly detects coherent signals and can be used, in our example, to extract homogeneous line widths. The same method used on a lead-halide perovskite photovoltaic cell shows that incoherent population mixing of mobile photocarriers can dominate the measured signal since carrier-carrier bimolecular scattering is active even at low excitation densities, which hides the coherent contribution to the spectral line shape. In this example, the intensity dependence of the signal matches the theoretical predictions over more than two orders of magnitude, confirming the incoherent nature of the signal. While these effects are typically not significant in dilute solution environments, we demonstrate the necessity to characterize, in condensed-phase materials systems, the extent of nonlinear population dynamics of photoexcitations (excitons, charge carriers, etc.) in the execution of this powerful population-detected coherent spectroscopy technique.

Structural and dynamical trends in alkali-metal silanides characterized by neutron-scattering methods

DOE PAGES

Tang, Wan Si; Dimitrievska, Mirjana; Chotard, Jean -Noel; ...

2016-09-02

Structural, vibrational, and dynamical properties of the mono- and mixed-alkali silanides (MSiH 3, where M = K, Rb, Cs, K 0.5Rb 0.5, K 0.5Cs 0.5, and Rb 0.5Cs 0.5) were investigated by various neutron experiments, including neutron powder diffraction (NPD), neutron vibrational spectroscopy (NVS), neutron-scattering fixed-window scans (FWSs), and quasielastic neutron scattering (QENS) measurements. Structural characterization showed that the mixed compounds exhibit disordered (α) and ordered (β) phases for temperatures above and below about 200–250 K, respectively, in agreement with their monoalkali correspondents. Vibrational and dynamical properties are strongly influenced by the cation environment; in particular, there is a redmore » shift in the band energies of the librational and bending modes with increasing lattice size as a result of changes in the bond lengths and force constants. Additionally, slightly broader spectral features are observed in the case of the mixed compounds, indicating the presence of structural disorder caused by the random distribution of the alkali-metal cations within the lattice. FWS measurements upon heating showed that there is a large increase in reorientational mobility as the systems go through the order–disorder (β–α) phase transition, and measurements upon cooling of the α-phase revealed the known strong hysteresis for reversion back to the β-phase. Interestingly, at a given temperature, among the different alkali silanide compounds, the relative reorientational mobilities of the SiH 3 – anions in the α- and β-phases tended to decrease and increase, respectively, with increasing alkali-metal mass. Lastly, this dynamical result might provide some insights concerning the enthalpy–entropy compensation effect previously observed for these potentially promising hydrogen storage materials.« less

Nonisovalent Si-III-V and Si-II-VI alloys: Covalent, ionic, and mixed phases

DOE PAGES

Kang, Joongoo; Park, Ji -Sang; Stradins, Pauls; ...

2017-07-13

In this paper, nonequilibrium growth of Si-III-V or Si-II-VI alloys is a promising approach to obtaining optically more active Si-based materials. We propose a new class of nonisovalent Si 2AlP (or Si 2ZnS) alloys in which the Al-P (or Zn-S) atomic chains are as densely packed as possible in the host Si matrix. As a hybrid of the lattice-matched parent phases, Si2AlP (or Si2ZnS) provides an ideal material system with tunable local chemical orders around Si atoms within the same composition and structural motif. Here, using first-principles hybrid functional calculations, we discuss how the local chemical orders affect the electronicmore » and optical properties of the nonisovalent alloys.« less

Opto-electronic device for frequency standard generation and terahertz-range optical demodulation based on quantum interference

DOEpatents

Georgiades, Nikos P.; Polzik, Eugene S.; Kimble, H. Jeff

1999-02-02

An opto-electronic system and technique for comparing laser frequencies with large frequency separations, establishing new frequency standards, and achieving phase-sensitive detection at ultra high frequencies. Light responsive materials with multiple energy levels suitable for multi-photon excitation are preferably used for nonlinear mixing via quantum interference of different excitation paths affecting a common energy level. Demodulation of a carrier with a demodulation frequency up to 100's THZ can be achieved for frequency comparison and phase-sensitive detection. A large number of materials can be used to cover a wide spectral range including the ultra violet, visible and near infrared regions. In particular, absolute frequency measurement in a spectrum from 1.25 .mu.m to 1.66 .mu.m for fiber optics can be accomplished with a nearly continuous frequency coverage.

Promoting the use of crumb rubber concrete in developing countries.

PubMed

Batayneh, Malek K; Marie, Iqbal; Asi, Ibrahim

2008-11-01

The use of accumulated waste materials in third world countries is still in its early phases. It will take courage for contractors and others in the construction industry to recycle selected types of waste materials in the concrete mixes. This paper addresses the recycling of rubber tires accumulated every year in Jordan to be used in concrete mixes. The main objectives of this research were to provide more scientific evidence to support the use of legislation or incentive-based schemes to promote the reuse of accumulated waste tires. This research focused on using crumb tires as a replacement for a percentage of the local fine aggregates used in the concrete mixes in Jordan. Different concrete specimens were prepared and tested in terms of uniaxial compression and splitting tension. The main variable in the mixture was the volumetric percentage of crumb tires used in the mix. The test results showed that even though the compressive strength is reduced when using the crumb tires, it can meet the strength requirements of light weight concrete. In addition, test results and observations indicated that the addition of crumb rubber to the mix has a limited effect toward reducing the workability of the mixtures. The mechanical test results demonstrated that the tested specimens of the crumb rubber concrete remained relatively intact after failure compared to the conventional concrete specimens. It is also concluded that modified concrete would contribute to the disposal of the non-decaying scrap tires, since the amount being accumulated in third world countries is creating a challenge for proper disposal. Thus, obliging authorities to invest in facilitating the use of waste tires in concrete, a fundamental material to the booming construction industry in theses countries, serves two purposes.

Joining Chemical Pressure and Epitaxial Strain to Yield Y-doped BiFeO3 Thin Films with High Dielectric Response

PubMed Central

Scarisoreanu, N. D.; Craciun, F.; Birjega, R.; Ion, V.; Teodorescu, V. S.; Ghica, C.; Negrea, R.; Dinescu, M.

2016-01-01

BiFeO3 is one of the most promising multiferroic materials but undergoes two major drawbacks: low dielectric susceptibility and high dielectric loss. Here we report high in-plane dielectric permittivity (ε’ ∼2500) and low dielectric loss (tan δ < 0.01) obtained on Bi0.95Y0.05FeO3 films epitaxially grown on SrTiO3 (001) by pulsed laser deposition. High resolution transmission electron microscopy and geometric phase analysis evidenced nanostripe domains with alternating compressive/tensile strain and slight lattice rotations. Nanoscale mixed phase/domain ensembles are commonly found in different complex materials with giant dielectric/electromechanical (ferroelectric/ relaxors) or magnetoresistance (manganites) response. Our work brings insight into the joined role of chemical pressure and epitaxial strain on the appearance of nanoscale stripe structure which creates conditions for easy reorientation and high dielectric response, and could be of more general relevance for the field of materials science where engineered materials with huge response to external stimuli are a highly priced target. PMID:27157090

Multimodal hard x-ray imaging with resolution approaching 10 nm for studies in material science

NASA Astrophysics Data System (ADS)

Yan, Hanfei; Bouet, Nathalie; Zhou, Juan; Huang, Xiaojing; Nazaretski, Evgeny; Xu, Weihe; Cocco, Alex P.; Chiu, Wilson K. S.; Brinkman, Kyle S.; Chu, Yong S.

2018-03-01

We report multimodal scanning hard x-ray imaging with spatial resolution approaching 10 nm and its application to contemporary studies in the field of material science. The high spatial resolution is achieved by focusing hard x-rays with two crossed multilayer Laue lenses and raster-scanning a sample with respect to the nanofocusing optics. Various techniques are used to characterize and verify the achieved focus size and imaging resolution. The multimodal imaging is realized by utilizing simultaneously absorption-, phase-, and fluorescence-contrast mechanisms. The combination of high spatial resolution and multimodal imaging enables a comprehensive study of a sample on a very fine length scale. In this work, the unique multimodal imaging capability was used to investigate a mixed ionic-electronic conducting ceramic-based membrane material employed in solid oxide fuel cells and membrane separations (compound of Ce0.8Gd0.2O2‑x and CoFe2O4) which revealed the existence of an emergent material phase and quantified the chemical complexity at the nanoscale.

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

NASA Astrophysics Data System (ADS)

Wiacek, A.; Peter, T.; Lohmann, U.

2010-09-01

This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T≲-40 °C) along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but subsaturated with respect to water, where so-called "warm ice clouds" (T≳-40 °C) theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice clouds" and the general influence of dust in the mixed-phase cloud region are highly uncertain due to both a considerable scatter in recent laboratory data from ice nucleation experiments, which we briefly review in this work, and due to uncertainties in sub-grid scale vertical transport processes unresolved by the present trajectory analysis. For "classical" cirrus-forming temperatures (T≲-40 °C), our results show that only mineral dust ice nuclei that underwent mixed-phase cloud-processing, most likely acquiring coatings of organic or inorganic material, are likely to be relevant. While the potential paucity of deposition ice nuclei shown in this work dimishes the possibility of deposition nucleation, the absence of liquid water droplets at T≲-40 °C makes the less explored contact freezing mechanism (involving droplet collisions with bare ice nuclei) highly inefficient. These factors together indicate the necessity of further systematic studies of immersion mode ice nucleation on mineral dust suspended in atmospherically relevant coatings.

Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

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

Wang, Zhien

2010-06-29

The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processesmore » is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model simulations. The ultimate goal is to improve our cloud classification algorithm into a VAP.« less

Impacts of Subgrid Heterogeneous Mixing between Cloud Liquid and Ice on the Wegner-Bergeron-Findeisen Process and Mixed-phase Clouds in NCAR CAM5

NASA Astrophysics Data System (ADS)

Liu, X.; Zhang, M.; Zhang, D.; Wang, Z.; Wang, Y.

2017-12-01

Mixed-phase clouds are persistently observed over the Arctic and the phase partitioning between cloud liquid and ice hydrometeors in mixed-phase clouds has important impacts on the surface energy budget and Arctic climate. In this study, we test the NCAR Community Atmosphere Model Version 5 (CAM5) with the single-column and weather forecast configurations and evaluate the model performance against observation data from the DOE Atmospheric Radiation Measurement (ARM) Program's M-PACE field campaign in October 2004 and long-term ground-based multi-sensor remote sensing measurements. Like most global climate models, we find that CAM5 also poorly simulates the phase partitioning in mixed-phase clouds by significantly underestimating the cloud liquid water content. Assuming pocket structures in the distribution of cloud liquid and ice in mixed-phase clouds as suggested by in situ observations provides a plausible solution to improve the model performance by reducing the Wegner-Bergeron-Findeisen (WBF) process rate. In this study, the modification of the WBF process in the CAM5 model has been achieved with applying a stochastic perturbation to the time scale of the WBF process relevant to both ice and snow to account for the heterogeneous mixture of cloud liquid and ice. Our results show that this modification of WBF process improves the modeled phase partitioning in the mixed-phase clouds. The seasonal variation of mixed-phase cloud properties is also better reproduced in the model in comparison with the long-term ground-based remote sensing observations. Furthermore, the phase partitioning is insensitive to the reassignment time step of perturbations.

Effect of trivalent iron substitution on structure and properties of PLZT ceramics

NASA Astrophysics Data System (ADS)

Dutta, S.; Choudhary, R. N. P.

2008-02-01

Polycrystalline samples of Fe-modified PLZT (lead lanthanum zirconate titanate) are prepared by a mixed-oxide reaction technique. The formation of the compound has been confirmed by X-ray powder diffraction studies. The unit cell structure of the material has been found to be rhombohedral. Fourier-transform infrared reflection (FTIR) spectra have been recorded to correspond the structural changes associated with the phase formation. The effects of Fe concentration on the microstructure and dielectric constant of PLZT materials have been investigated. The ferroelectric phase transition of PLFZT materials is studied using dielectric measurements, which shows a shift in the transition temperature towards the higher-temperature side with increased Fe ion concentration. The piezoelectric constants of this system are investigated by the same way of changed contents of Fe ion in the main PLZT compound. The optimum values of Qm, kp, and d33 are 73, 0.32 and 406. The electrical conductivity increases with the increase in Fe ion concentration.

Feasibility of using phase change materials to control the heat of hydration in massive concrete structures.

PubMed

Choi, Won-Chang; Khil, Bae-Soo; Chae, Young-Seok; Liang, Qi-Bo; Yun, Hyun-Do

2014-01-01

This paper presents experimental results that can be applied to select a possible phase change material (PCM), such as a latent heat material (LHM), to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests) were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH)2 · 8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

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.

Grout Isolation and Stabilization of Structures and Materials within Nuclear Facilities at the U.S. Department of Energy, Hanford Site, Summary - 12309

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

Phillips, S.J.; Phillips, M.; Etheridge, D.

2012-07-01

Per regulatory agreement and facility closure design, U.S. Department of Energy Hanford Site nuclear fuel cycle structures and materials require in situ isolation in perpetuity and/or interim physicochemical stabilization as a part of final disposal or interim waste removal, respectively. To this end, grout materials are being used to encase facilities structures or are being incorporated within structures containing hazardous and radioactive contaminants. Facilities where grout materials have been recently used for isolation and stabilization include: (1) spent fuel separations, (2) uranium trioxide calcining, (3) reactor fuel storage basin, (4) reactor fuel cooling basin transport rail tanker cars and casks,more » (5) cold vacuum drying and reactor fuel load-out, and (6) plutonium fuel metal finishing. Grout components primarily include: (1) portland cement, (2) fly ash, (3) aggregate, and (4) chemical admixtures. Mix designs for these typically include aggregate and non aggregate slurries and bulk powders. Placement equipment includes: (1) concrete piston line pump or boom pump truck for grout slurry, (2) progressive cavity and shearing vortex pump systems, and (3) extendable boom fork lift for bulk powder dry grout mix. Grout slurries placed within the interior of facilities were typically conveyed utilizing large diameter slick line and the equivalent diameter flexible high pressure concrete conveyance hose. Other facilities requirements dictated use of much smaller diameter flexible grout conveyance hose. Placement required direct operator location within facilities structures in most cases, whereas due to radiological dose concerns, placement has also been completed remotely with significant standoff distances. Grout performance during placement and subsequent to placement often required unique design. For example, grout placed in fuel basin structures to serve as interim stabilization materials required sufficient bearing i.e., unconfined compressive strength, to sustain heavy equipment yet, low breakout force to permit efficient removal by track hoe bucket or equivalent construction equipment. Further, flow of slurries through small orifice geometries of moderate head pressures was another typical design requirement. Phase separation of less than 1 percent was a typical design requirement for slurries. On the order of 30,000 cubic meters of cementitious grout have recently been placed in the above noted U.S. Department of Energy Hanford Site facilities or structures. Each has presented a unique challenge in mix design, equipment, grout injection or placement, and ultimate facility or structure performance. Unconfined compressive and shear strength, flow, density, mass attenuation coefficient, phase separation, air content, wash-out, parameters and others, unique to each facility or structure, dictate the grout mix design for each. Each mix design was tested under laboratory and scaled field conditions as a precursor to field deployment. Further, after injection or placement of each grout formulation, the material was field inspected either by standard laboratory testing protocols, direct physical evaluation, or both. (authors)« less

A Laterally-Mobile Mixed Polymer/Polyelectrolyte Brush Undergoes a Macroscopic Phase Separation

NASA Astrophysics Data System (ADS)

Lee, Hoyoung; Park, Hae-Woong; Tsouris, Vasilios; Choi, Je; Mustafa, Rafid; Lim, Yunho; Meron, Mati; Lin, Binhua; Won, You-Yeon

2013-03-01

We studied mixed PEO and PDMAEMA brushes. The question we attempted to answer was: When the chain grafting points are laterally mobile, how will this lateral mobility influence the structure and phase behavior of the mixed brush? Two different model mixed PEO/PDMAEMA brush systems were prepared: a mobile mixed brush by spreading a mixture of two diblock copolymers, PEO-PnBA and PDMAEMA-PnBA, onto the air-water interface, and an inseparable mixed brush using a PEO-PnBA-PDMAEMA triblock copolymer having respective brush molecular weights matched to those of the diblock copolymers. These two systems were investigated by surface pressure-area isotherm, X-ray reflectivity and AFM imaging measurements. The results suggest that the mobile mixed brush undergoes a lateral macroscopic phase separation at high chain grafting densities, whereas the inseparable system is only microscopically phase separated under comparable brush density conditions. We also conducted an SCF analysis of the phase behavior of the mixed brush system. This analysis further supported the experimental findings. The macroscopic phase separation observed in the mobile system is in contrast to the microphase separation behavior commonly observed in two-dimensional laterally-mobile small molecule mixtures.

30 CFR 57.6960 - Mixing of explosive material.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Mixing of explosive material. 57.6960 Section... General Requirements-Underground Only § 57.6960 Mixing of explosive material. (a) The mixing of... to the hazards associated with the mixing of the bulk explosive material underground. (b) Storage...

30 CFR 57.6960 - Mixing of explosive material.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Mixing of explosive material. 57.6960 Section... General Requirements-Underground Only § 57.6960 Mixing of explosive material. (a) The mixing of... to the hazards associated with the mixing of the bulk explosive material underground. (b) Storage...

30 CFR 57.6960 - Mixing of explosive material.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Mixing of explosive material. 57.6960 Section... General Requirements-Underground Only § 57.6960 Mixing of explosive material. (a) The mixing of... to the hazards associated with the mixing of the bulk explosive material underground. (b) Storage...

30 CFR 57.6960 - Mixing of explosive material.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Mixing of explosive material. 57.6960 Section... General Requirements-Underground Only § 57.6960 Mixing of explosive material. (a) The mixing of... to the hazards associated with the mixing of the bulk explosive material underground. (b) Storage...

30 CFR 57.6960 - Mixing of explosive material.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Mixing of explosive material. 57.6960 Section... General Requirements-Underground Only § 57.6960 Mixing of explosive material. (a) The mixing of... to the hazards associated with the mixing of the bulk explosive material underground. (b) Storage...

Inducing phase transitions of T-like BiFeO3 films by low-energy He implantation

NASA Astrophysics Data System (ADS)

Herklotz, Andreas; Beekman, Christianne; Rus, Stefania Florina; Ivanov, Ilia; Balke, Nina; Ward, Thomas Zac

Ferroelectric phase transitions of BiFeO3 are found to be controllable through the application of single axis, out-of-plane strain. Low-energy He implantation has been deployed to induce out-of-plane strain in T-like BFO films, while the compressive in-plane strain due to the coherent growth on LaAlO3 substrates remains fixed. Our data shows that He implantation triggers a MC -MA - T phase sequence of the T polymorph that is identical to structural changes that are induced with increasing temperature. Mixed phases nanodomains phases are gradually suppressed and disappear above a certain He doping level. Our data shows that the ferroelectric and optical properties of BiFeO3 films critically depend on the He doping level. Thus, the results demonstrates that He implantation can be used as an intriguing approach to study lines in the rich phase space of BFO films that can't be accessed by simple heteroepitaxy. This effort was wholly supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division, with user projects supported at ORNL's Center for Nanophase Materials Research (CNMS) which is also sponsored by DOE-BES.

Solid state proton and electron mediating membrane and use in catalytic membrane reactors

DOEpatents

White, J.H.; Schwartz, M.; Sammells, A.F.

1998-10-13

This invention provides catalytic proton and electron mediating membranes useful in catalytic reactors. The membranes have an oxidation and a reduction surface and comprise a single-phase mixed metal oxide material of the formula: AB{sub 1{minus}x}B{prime}{sub x}O{sub 3{minus}y} wherein A is selected from Ca, Sr or Ba ions; B is selected from Ce, Tb, Pr, or Th ions; B{prime} is selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Ga, or In ions, or combinations thereof; and x is greater than or equal to 0.02 and less than or equal to 0.5. The membranes can further comprise a catalyst on either the oxidation or reduction surface, or both. Membranes include those which are fabricated by combining powders of metal oxides or metal carbonates of metal A ion, metal B ion and metal B{prime} ion such that the stoichiometric ratio A:B:B{prime} is 1:1{minus}x:x where 0.2{<=}{times}0.5, repeatedly calcining and milling the combined powders until a single-phase material is obtained and pressing and sintering the single phase material to obtain a membrane. 6 figs.

In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

NASA Technical Reports Server (NTRS)

Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

2013-01-01

A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

Synthesis of C-rich dust in CO nova outbursts

NASA Astrophysics Data System (ADS)

José, Jordi; Halabi, Ghina M.; El Eid, Mounib F.

2016-09-01

Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M⊙, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf. Aims: Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected. Methods: To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M⊙ through H- and He-burning phases. Results: We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (I.e., nanodiamonds, silicon carbides, and graphites).

Thermonuclear runaways in nova outbursts. 2: Effect of strong, instantaneous, local fluctuations

NASA Technical Reports Server (NTRS)

Shankar, Anurag; Arnett, David

1994-01-01

In an attempt to understand the manner in which nova outbursts are initiated on the surface of a white dwarf, we investigate the effects fluctuations have on the evolution of a thermonuclear runaway. Fluctuations in temperature density, or the composition of material in the burning shell may arise due to the chaotic flow field generated by convection when it occurs, or by the accretion process itself. With the aid of two-dimensional reactive flow calculations, we consider cases where a strong fluctutation in temperature arises during the early, quiescent accretion phase or during the later, more dynamic, explosion phase. In all cases we find that an instantaneous, local temperature fluctuation causes the affected material to become Rayleigh-Taylor unstable. The rapid rise and subsequent expansion of matter immediately cools the hot blob, which prevents the lateral propagation of burning. This suggests that local temperature fluctuations do not play a significant role in directly initiating the runaway, especially during the early stages. However, they may provide an efficient mechanism of mixing core material into the envelope (thereby pre-enriching the fuel for subsequent episodes of explosive hydrogen burning) and of mixing substantial amounts of the radioactive nucleus N-13 into the surface layers, making novae potential gamma-ray sources. This suggests that it is the global not the local, evolution of the core-envelope interface to high temperatures which dominates the development of the runaway. We also present a possible new scenario for the initiation of nova outbursts based on our results.

Phase quantification by X-ray photoemission valence band analysis applied to mixed phase TiO2 powders

NASA Astrophysics Data System (ADS)

Breeson, Andrew C.; Sankar, Gopinathan; Goh, Gregory K. L.; Palgrave, Robert G.

2017-11-01

A method of quantitative phase analysis using valence band X-ray photoelectron spectra is presented and applied to the analysis of TiO2 anatase-rutile mixtures. The valence band spectra of pure TiO2 polymorphs were measured, and these spectral shapes used to fit valence band spectra from mixed phase samples. Given the surface sensitive nature of the technique, this yields a surface phase fraction. Mixed phase samples were prepared from high and low surface area anatase and rutile powders. In the samples studied here, the surface phase fraction of anatase was found to be linearly correlated with photocatalytic activity of the mixed phase samples, even for samples with very different anatase and rutile surface areas. We apply this method to determine the surface phase fraction of P25 powder. This method may be applied to other systems where a surface phase fraction is an important characteristic.

Thermodynamic functions, freezing transition, and phase diagram of dense carbon-oxygen mixtures in white dwarfs

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

Iyetomi, H.; Ogata, S.; Ichimaru, S.

1989-07-01

Equations of state for dense carbon-oxygen (C-O) binary-ionic mixtures (BIM's) appropriate to the interiors of white dwarfs are investigated through Monte Carlo simulations, by solution of relevant integral equations andvariational calculations in the density-functional formalism. It is thereby shown that the internal energies of the C-O BIM solids and fluids both obey precisely the linear mixing formulas. We then present an accurate calculation of the phase diagram associated with freezing transitions in such BIM materials, resulting in a novel prediction of an azeotropic diagram. Discontinuities of the mass density across the azeotropic phase boundaries areevaluated numerically for application to amore » study of white-dwarf evolution.« less

Understanding the Use of Graphic Novels to Support the Writing Skills of a Struggling Writer

ERIC Educational Resources Information Center

Voss, Christina L.

2013-01-01

This mixed methods study combining a single-subject experimental design with an embedded case study focuses on the impact of a visual treatment on the handwritten and typed output of a struggling male writer during his 5th through 7th grades who has undergone a longitudinal remedial phase of two and a half years creating text-only material as well…

Criteria for predicting the formation of single-phase high-entropy alloys

DOE PAGES

Troparevsky, M Claudia; Morris, James R..; Kent, Paul R.; ...

2015-03-15

High entropy alloys constitute a new class of materials whose very existence poses fundamental questions. Originally thought to be stabilized by the large entropy of mixing, these alloys have attracted attention due to their potential applications, yet no model capable of robustly predicting which combinations of elements will form a single-phase currently exists. Here we propose a model that, through the use of high-throughput computation of the enthalpies of formation of binary compounds, is able to confirm all known high-entropy alloys while rejecting similar alloys that are known to form multiple phases. Despite the increasing entropy, our model predicts thatmore » the number of potential single-phase multicomponent alloys decreases with an increasing number of components: out of more than two million possible 7-component alloys considered, fewer than twenty single-phase alloys are likely.« less

Development studies for a novel wet oxidation process. Phase 2

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

NONE

1994-07-01

DETOX{sup SM} is a catalyzed wet oxidation process which destroys organic materials in an acidic water solution of iron at 373 to 473 K. The solution can be used repeatedly to destroy great amounts of organic materials. Since the process is conducted in a contained vessel, air emissions from the process can be well controlled. The solution is also capable of dissolving and concentrating many heavy and radioactive metals for eventual stabilization and disposal. The Phase 2 effort for this project is site selection and engineering design for a DETOX demonstration unit. Site selection was made using a set ofmore » site selection criteria and evaluation factors. A survey of mixed wastes at DOE sites was conducted using the Interim Mixed Waste Inventory Report. Sites with likely suitable waste types were identified. Potential demonstration sites were ranked based on waste types, interest, regulatory needs, scheduling, ability to provide support, and available facilities. Engineering design for the demonstration unit is in progress and is being performed by Jacobs Applied Technology. The engineering design proceeded through preliminary process flow diagrams (PFDs), calculation of mass and energy balances for representative waste types, process and instrumentation diagrams (P and IDs), preparation of component specifications, and a firm cost estimate for fabrication of the demonstration unit.« less

Hydrothermal synthesis and enhanced photocatalytic activity of mixed-phase TiO2 powders with controllable anatase/rutile ratio

NASA Astrophysics Data System (ADS)

Wang, Qi; Qiao, Zhi; Jiang, Peng; Kuang, Jianlei; Liu, Wenxiu; Cao, Wenbin

2018-03-01

In this study, mixed-phase TiO2 powders were novelly synthesized via a facile and mild hydrothermal method without any post-heat treatment. TiOSO4 and peroxide titanic acid (PTA) were used as inorganic titanium sources, while no special solvent or additive were introduced. The XRD and TEM results showed the mixed-phase TiO2 powders were composed of anatase and rutile phases, and the PTA sol played an important role on forming the rutile nucleus. The proportion of rutile in the mixed-phase TiO2 could be easily controlled in the range of 0%-70.5% by changing the amount of PTA sol used in the synthesis process. The UV-Visible absorption spectra indicated the prepared mixed-phase TiO2 showed enhanced visible light absorption with the increase of rutile ratio. The photodegradation experiments revealed the mixed-phase TiO2 exhibited the best photocatalytic activity at the rutile ratio of 41.5%, while a higher or lower rutile ratio both resulted in the decrease of photocatalytic activity.

Ship track observations of a reduced shortwave aerosol indirect effect in mixed-phase clouds

NASA Astrophysics Data System (ADS)

Christensen, M. W.; Suzuki, K.; Zambri, B.; Stephens, G. L.

2014-10-01

Aerosol influences on clouds are a major source of uncertainty to our understanding of forced climate change. Increased aerosol can enhance solar reflection from clouds countering greenhouse gas warming. Recently, this indirect effect has been extended from water droplet clouds to other types including mixed-phase clouds. Aerosol effects on mixed-phase clouds are important because of their fundamental role on sea ice loss and polar climate change, but very little is known about aerosol effects on these clouds. Here we provide the first analysis of the effects of aerosol emitted from ship stacks into mixed-phase clouds. Satellite observations of solar reflection in numerous ship tracks reveal that cloud albedo increases 5 times more in liquid clouds when polluted and persist 2 h longer than in mixed-phase clouds. These results suggest that seeding mixed-phase clouds via shipping aerosol is unlikely to provide any significant counterbalancing solar radiative cooling effects in warming polar regions.

Porous mixed metal oxides: design, formation mechanism, and application in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Fangfang; Bai, Jing; Feng, Jinkui; Xiong, Shenglin

2015-10-01

The relentless pursuit of new electrode materials for lithium ion batteries (LIBs) has been conducted for decades. Structures with either porous or nanostructure configurations have been confirmed as advantageous candidates for energy storage/conversion applications. The integration of the two features into one structure can provide another chance to improve the electroactivities. Recently, single-phased mixed metal oxides (MMOs) containing different metal cations, in particular, have confirmed high electrochemical activities because of their complex chemical composition, interfacial effects, and the synergic effects of the multiple metal species. In this review, we will focus on recent research advances of MMOs with porous architectures as anode materials in the matter of structural arrangement and compositional manipulation. Moreover, the application of self-supported MMO-based porous structures as LIB anodes is also explained herein. More importantly, investigations on the synthetic system and formation mechanism of porous MMOs will be highlighted. Some future trends for the innovative design of new electrode materials are also discussed in this review. The challenges and prospects will draw many researchers' attention.

Nanoparticulate, sub-micron and micron sized particles emanating from hydrothermal vents

NASA Astrophysics Data System (ADS)

Luther, G. W., III; Gartman, A.; Findlay, A.; Yucel, M.; Chan, C. S. Y.

2015-12-01

Recent data from Geotraces cruises over the MAR and SEPR indicate dissolved and particulate Fe enrichment in waters 1000 and 4000 km from their vent sources, respectively. Deep-sea hydrothermal vents and the waters in the reactive mixing zone above vent orifices have been suggested to be an important source of fine material that can pass through normal filters (0.2 and 0.4 μm). In this work, nanoparticles are defined operationally as that which can pass through a 0.2 μm filter. We investigated two vent sites (Lau Basin and the MAR). Chimneys from both vent sites have fluids that can be sulfide rich or metal rich. We also present chemical and physical chemical data (SEM-EDS, TEM, XRD, EELS) showing some of the materials found in these (nano)particulate phases including pyrite, metal sulfides, silicate and aluminosilicate material. Enrichment of Mg and K in the latter suggest that reverse weathering may occur in the waters within 1-2 meters of the vent orifice where vent waters mix with cold oxygenated bottom waters.

Geometric phase of mixed states for three-level open systems

NASA Astrophysics Data System (ADS)

Jiang, Yanyan; Ji, Y. H.; Xu, Hualan; Hu, Li-Yun; Wang, Z. S.; Chen, Z. Q.; Guo, L. P.

2010-12-01

Geometric phase of mixed state for three-level open system is defined by establishing in connecting density matrix with nonunit vector ray in a three-dimensional complex Hilbert space. Because the geometric phase depends only on the smooth curve on this space, it is formulated entirely in terms of geometric structures. Under the limiting of pure state, our approach is in agreement with the Berry phase, Pantcharatnam phase, and Aharonov and Anandan phase. We find that, furthermore, the Berry phase of mixed state correlated to population inversions of three-level open system.

Tradeoffs in Chemical and Thermal Variations in the Post-perovskite Phase Transition: Mixed Phase Regions in the Deep Lower Mantle?

NASA Astrophysics Data System (ADS)

Giles, G. F.; Spera, F. J.; Yuen, D. A.

2005-12-01

The recent discovery of a phase-transition in Mg-rich perovskite (Pv) to a post-perovskite (pPv) phase at lower mantle depths and its relationship to D", lower mantle heterogeneity and iron content prompted an investigation of the relative importance of lower mantle (LM) compositional and temperature fluctuations in creating topographic undulations on mixed phase regions. Above the transition, Mg-rich Pv makes up ~70 percent by mass of the LM. Using results from experimental phase equilibria, first-principles computations and thermodynamic relations for Fe2+-Mg mixing in silicates, a preliminary thermodynamic model for the perovskite to post-perovskite phase transition in the divariant system MgSiO3-FeSiO3 is developed. Complexities associated with components Fe2O3 and Al2O3 and other phases (Ca-Pv, magnesiowustite) are neglected. The model predicts phase transition pressures are sensitive to the FeSiO3 content of perovskite (~-1.5 GPa per one mole percent FeSiO3). This leads to considerable topography along the top boundary of the mixed phase region. The Clapeyron slope for the Pv to pPv transition at XFeSiO3=0.1 is +11 MPa/K about 20% higher than for pure Mg-Pv. Increasing bulk concentration of iron elevates the mixed (two-phase) layer above the core-mantle boundary (CMB); increasing temperature acts to push the mixed layer deeper into the LM into the D" thermal boundary layer resting upon the (CMB). For various LM geotherms and CMB temperatures, a single mixed layer of thickness ~300 km lies within the bottom 40% of the lower mantle. For low iron contents (XFeSiO3 ~5 mole percent or less), two perched layers are found. This is the divariant analog to the univariant double-crosser. The hotter the mantle, the deeper the mixed phase layer; the more iron-rich the LM, the higher the mixed phase layer. In a hotter Hadean Earth with interior temperatures everywhere 200-500 K warmer pPv is not stable unless the LM bulk composition is Fe-enriched compared to the present upper mantle.

Physical properties of sequential interpenetrating polymer networks produced from canola oil-based polyurethane and poly(methyl methacrylate).

PubMed

Kong, Xiaohua; Narine, Suresh S

2008-05-01

Sequential interpenetrating polymer networks (IPNs) were prepared using polyurethane (PUR) synthesized from canola oil-based polyol with terminal primary functional groups and poly(methyl methacrylate) (PMMA). The properties of the material were evaluated by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and modulated differential scanning calorimetry (MDSC), as well as tensile properties measurements. The morphology of the IPNs was investigated using scanning electron microscopy (SEM) and MDSC. A five-phase morphology, that is, sol phase, PUR-rich phase, PUR-rich interphase, PMMA-rich interphase, and PMMA-rich phase, was observed for all the IPNs by applying a new quantitative method based on the measurement of the differential of reversing heat capacity versus temperature from MDSC, although not confirmed by SEM, most likely due to resolution restrictions. NCO/OH molar ratios (cross-linking density) and compositional variations of PUR/PMMA both affected the thermal properties and phase behaviors of the IPNs. Higher degrees of mixing occurred for the IPN with higher NCO/OH molar ratio (2.0/1.0) at PUR concentration of 25 wt %, whereas for the IPN with lower NCO/OH molar ratio (1.6/1.0), higher degrees of mixing occurred at PUR concentration of 35 wt %. The mechanical properties of the IPNs were superior to those of the constituent polymers due to the finely divided rubber and plastic combination structures in these IPNs.

Sulfate resistance of high calcium fly ash concrete

NASA Astrophysics Data System (ADS)

Dhole, Rajaram

Sulfate attack is one of the mechanisms which can cause deterioration of concrete. In general, Class C fly ash mixtures are reported to provide poor sulfate resistance. Fly ashes, mainly those belonging to the Class C, were tested as per the ASTM C 1012 procedure to evaluate chemical sulfate resistance. Overall the Class C fly ashes showed poor resistance in the sulfate environment. Different strategies were used in this research work to improve the sulfate resistance of Class C fly ash mixes. The study revealed that some of the strategies such as use of low W/CM (water to cementing materials by mass ratio), silica fume or ultra fine fly ash, high volumes of fly ash and, ternary or quaternary mixes with suitable supplementary cementing materials, can successfully improve the sulfate resistance of the Class C fly ash mixes. Combined sulfate attack, involving physical and chemical action, was studied using sodium sulfate and calcium sulfate solutions. The specimens were subjected to wetting-drying cycles and temperature changes. These conditions were found to accelerate the rate of degradation of concrete placed in a sodium sulfate environment. W/CM was found to be the main governing factor in providing sulfate resistance to mixes. Calcium sulfate did not reveal damage as a result of mainly physical action. Characterization of the selected fly ashes was undertaken by using SEM, XRD and the Rietveld analysis techniques, to determine the relation between the composition of fly ashes and resistance to sulfate attack. The chemical composition of glass represented on the ternary diagram was the main factor which had a significant influence on the sulfate resistance of fly ash mixtures. Mixes prepared with fly ashes containing significant amounts of vulnerable crystalline phases offered poor sulfate resistance. Comparatively, fly ash mixes containing inert crystalline phases such as quartz, mullite and hematite offered good sulfate resistance. The analysis of hydrated lime-fly ash pastes confirmed that fly ash mortar or concrete mixes forming more monosulfate than ettringite before exposure to sulfates would offer poor sulfate resistance and vice versa. During quantitative Rietveld analysis carried out for determining ettringite, monosulfate and gypsum formed in the fly ash pastes, it was observed that fly ash mixtures showing more ettringite after exposures to sulfates, give poor sulfate resistance. A good relationship between the amounts of ettringite formed and expansions of mortar specimens in the ASTM C 1012 test was found.

Biodegradation of polyether-polyol-based polyurethane elastomeric films: influence of partial replacement of polyether polyol by biopolymers of renewable origin.

PubMed

Obruca, Stanislav; Marova, Ivana; Vojtova, Lucy

2011-07-01

In this work we investigated the degradation process ofpolyether-polyol-based polyurethane (PUR) elastomeric films in the presence of a mixed thermophilic culture as a model of a natural bacterial consortium. The presence of PUR material in cultivation medium resulted in delayed but intensive growth of the bacterial culture. The unusually long lag phase was caused by the release of unreacted polyether polyol and tin catalyst from the material. The lag phase was significantly shortened and the biodegradability of PUR materials was enhanced by partial replacement (10%) of polyether polyol with biopolymers (carboxymethyl cellulose, hydroxyethyl cellulose, acetyl cellulose and actylated starch). The process of material degradation consisted of two steps. First, the materials were mechanically disrupted and, second, the bacterial culture was able to utilize abiotic degradation products, which resulted in supported bacterial growth. Direct utilization of PUR by the bacterial culture was observed as well, but the bacterial culture contributed only slightly to the total mass losses. The only exception was PUR material modified by acetyl cellulose. In this case, direct biodegradation represented the major mechanism of material decomposition. Moreover, PUR material modified by acetyl cellulose did not tend to undergo abiotic degradation. In conclusion, the modification of PUR by proper biopolymers is a promising strategy for reducing potential negative effects of waste PUR materials on the environment and enhancing their biodegradability.

Apparatus for remote handling of materials. [mixing or analyzing dangerous chemicals

NASA Technical Reports Server (NTRS)

Kimball, R. B.; Hodder, D. T.; Wrinkle, W. W. (Inventor)

1974-01-01

Apparatus for remote handling of materials are described. A closed housing is provided with first and second containers and first and second reservoirs for holding materials to be mixed. The materials are transferable from the reservoirs to the first container where they are mixed. The mixed materials are then conveyed from the first container to the second container preferably by dumping the mixed materials into a funnel positioned over the second container. The second container is then moved to a second position for analysis of the mixed materials. For example, the materials may be ignited and the flame analyzed. Access, such as a sight port, is provided in the housing at the analysis position. The device provides a simple and inexpensive apparatus for safely mixing a pyrophoric material and an oxidizer which together form a thermite type mixture that burns to produce a large quantity of heat and light.

Simulations of Turbulent Flows with Strong Shocks and Density Variations: Final Report

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

Sanjiva Lele

2012-10-01

The target of this SciDAC Science Application was to develop a new capability based on high-order and high-resolution schemes to simulate shock-turbulence interactions and multi-material mixing in planar and spherical geometries, and to study Rayleigh-Taylor and Richtmyer-Meshkov turbulent mixing. These fundamental problems have direct application in high-speed engineering flows, such as inertial confinement fusion (ICF) capsule implosions and scramjet combustion, and also in the natural occurrence of supernovae explosions. Another component of this project was the development of subgrid-scale (SGS) models for large-eddy simulations of flows involving shock-turbulence interaction and multi-material mixing, that were to be validated with the DNSmore » databases generated during the program. The numerical codes developed are designed for massively-parallel computer architectures, ensuring good scaling performance. Their algorithms were validated by means of a sequence of benchmark problems. The original multi-stage plan for this five-year project included the following milestones: 1) refinement of numerical algorithms for application to the shock-turbulence interaction problem and multi-material mixing (years 1-2); 2) direct numerical simulations (DNS) of canonical shock-turbulence interaction (years 2-3), targeted at improving our understanding of the physics behind the combined two phenomena and also at guiding the development of SGS models; 3) large-eddy simulations (LES) of shock-turbulence interaction (years 3-5), improving SGS models based on the DNS obtained in the previous phase; 4) DNS of planar/spherical RM multi-material mixing (years 3-5), also with the two-fold objective of gaining insight into the relevant physics of this instability and aiding in devising new modeling strategies for multi-material mixing; 5) LES of planar/spherical RM mixing (years 4-5), integrating the improved SGS and multi-material models developed in stages 3 and 5. This final report is outlined as follows. Section 2 shows an assessment of numerical algorithms that are best suited for the numerical simulation of compressible flows involving turbulence and shock phenomena. Sections 3 and 4 deal with the canonical shock-turbulence interaction problem, from the DNS and LES perspectives, respectively. Section 5 considers the shock-turbulence inter-action in spherical geometry, in particular, the interaction of a converging shock with isotropic turbulence as well as the problem of the blast wave. Section 6 describes the study of shock-accelerated mixing through planar and spherical Richtmyer-Meshkov mixing as well as the shock-curtain interaction problem In section 7 we acknowledge the different interactions between Stanford and other institutions participating in this SciDAC project, as well as several external collaborations made possible through it. Section 8 presents a list of publications and presentations that have been generated during the course of this SciDAC project. Finally, section 9 concludes this report with the list of personnel at Stanford University funded by this SciDAC project.« less

Phase Tomography Reconstructed by 3D TIE in Hard X-ray Microscope

NASA Astrophysics Data System (ADS)

Yin, Gung-Chian; Chen, Fu-Rong; Pyun, Ahram; Je, Jung Ho; Hwu, Yeukuang; Liang, Keng S.

2007-01-01

X-ray phase tomography and phase imaging are promising ways of investigation on low Z material. A polymer blend of PE/PS sample was used to test the 3D phase retrieval method in the parallel beam illuminated microscope. Because the polymer sample is thick, the phase retardation is quite mixed and the image can not be distinguished when the 2D transport intensity equation (TIE) is applied. In this study, we have provided a different approach for solving the phase in three dimensions for thick sample. Our method involves integration of 3D TIE/Fourier slice theorem for solving thick phase sample. In our experiment, eight sets of de-focal series image data sets were recorded covering the angular range of 0 to 180 degree. Only three set of image cubes were used in 3D TIE equation for solving the phase tomography. The phase contrast of the polymer blend in 3D is obviously enhanced, and the two different groups of polymer blend can be distinguished in the phase tomography.

Phase transformation of mixed-phase clouds

NASA Astrophysics Data System (ADS)

Korolev, Alexei; Isaac, George

2003-01-01

The glaciation time of a mixed-phase cloud due to the Wegener-Bergeron-Findeisen mechanism is calculated using an adiabatic one-dimensional numerical model for the cases of zero, ascending, descending and oscillating vertical velocities. The characteristic values of the glaciation time are obtained for different concentrations of ice particles and liquid-water content. Steady state is not possible for the ice-water content/total water content ratio in a uniformly vertically moving mixed-phase parcel. The vertical oscillation of a cloud parcel may result in a periodic evaporation and activation of liquid droplets in the presence of ice particles during infinite time. After a certain time, the average ice-water content and liquid-water content reach a steady state. This phenomenon may explain the existence of long-lived mixed-phase stratiform layers. The obtained results are important for understanding the mechanisms of formation and life cycle of mixed-phase clouds.

Facile preparation of highly-dispersed cobalt-silicon mixed oxide nanosphere and its catalytic application in cyclohexane selective oxidation

PubMed Central

2011-01-01

Highly dispersed cobalt-silicon mixed oxide [Co-SiO2] nanosphere was successfully prepared with a modified reverse-phase microemulsion method. This material was characterized in detail by X-ray diffraction, transmission electron microscopy, Fourier transform infrared, ultraviolet-visible diffuse reflectance spectra, X-ray absorption spectroscopy near-edge structure, and N2 adsorption-desorption measurements. High valence state cobalt could be easily obtained without calcination, which is fascinating for the catalytic application for its strong oxidation ability. In the selective oxidation of cyclohexane, Co-SiO2 acted as an efficient catalyst, and good activity could be obtained under mild conditions. PMID:22067075

Phase Stabilization of Zirconia.

DTIC Science & Technology

1997-01-30

preparing stabilized zirconia pursuant to this disclosure, an insoluble alumina powder is mixed with zirconia powder using a liquid dispersant, such...in a drying oven or a furnace. When mixing the alumina and zirconia powders , it is not necessary to have zirconia in any particular phase to achieve...phase stabilization, as disclosed herein. When mixed with alumina powder, zirconia powder can be in cubic, tetragonal or 20 monoclinic phases

Methods for forming small-volume electrical contacts and material manipulations with fluid microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-12-27

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-04-26

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microehannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-03-22

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2007-11-20

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael; Culbertson, Christopher T.; Whitten, William B.; Foote, Robert S.

2004-02-03

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Extraterrestrial materials processing

NASA Technical Reports Server (NTRS)

Steurer, W. H.

1982-01-01

The first year results of a multi-year study of processing extraterrestrial materials for use in space are summarized. Theoretically, there are potential major advantages to be derived from the use of such materials for future space endeavors. The types of known or postulated starting raw materials are described including silicate-rich mixed oxides on the Moon, some asteroids and Mars; free metals in some asteroids and in small quantities in the lunar soil; and probably volatiles like water and CO2 on Mars and some asteroids. Candidate processes for space materials are likely to be significantly different from their terrestrial counterparts largely because of: absence of atmosphere; lack of of readily available working fluids; low- or micro-gravity; no carbon-based fuels; readily available solar energy; and severe constraints on manned intervention. The extraction of metals and oxygen from lunar material by magma electrolysis or by vapor/ion phase separation appears practical.

Synthesis and characterization of mesoporous ceria/alumina nanocomposite materials via mixing of the corresponding ceria and alumina gel precursors.

PubMed

Khalil, Kamal M S

2007-03-01

Mesoporous ceria/alumina, CeO(2)/Al(2)O(3), composites containing 10, 20 and 30% (w/w) ceria were prepared by a novel gel mixing method. In the method, ceria gel (formed via hydrolysis of ammonium cerium(IV) nitrate by aqueous ammonium carbonate solution) and alumina gel (formed via controlled hydrolysis of aluminum tri-isopropoxide) were mixed together. The mixed gel was subjected to subsequent drying and calcination for 3 h at 400, 600, 800 and 1000 degrees C. The uncalcined (dried at 110 degrees C) and the calcined composites were investigated by different techniques including TGA, DSC, FTIR, XRD, SEM and nitrogen adsorption/desorption isotherms. Results indicated that composites calcined for 3 h at 800 degrees C mainly kept amorphous alumina structure and gamma-alumina formed only upon calcinations at 1000 degrees C. On the other hand, CeO(2) was found to crystallize in the common ceria, cerinite, phase and it kept this structure over the entire calcination range (400-1000 degrees C). Therefore, high surface areas, stable surface textures, and non-aggregated nano-sized ceria dispersions were obtained. A systematic texture change based on ceria ratio was observed, however in all cases mesoporous composite materials exposing thermally stable texture and structure were obtained. The presented method produces composite ceria/alumina materials that suit different applications in the field of catalysis and membranes technology, and throw some light on physicochemical factors that determine textural morphology and thermal stability of such important composite.

Enhancing Biodiesel from Kemiri Sunan Oil Manufacturing using Ultrasonics

NASA Astrophysics Data System (ADS)

Supriyadi, Slamet; Purwanto; Anggoro, Didi Dwi; Hermawan

2018-02-01

Kemiri Sunan (Reutalis trisperma (Blanco) Airy Shaw) is a potential plant to be developed as biodiesel feedstock. The advantage of Kemiri Sunan seeds when compared to other biodiesel raw materials is their high oil content. This plant is also very good for land conservation. Due the increasingly demand for biodiesel, research and new methods to increase its biodiesel production continue to be undertaken. The weakness of conventional biodiesel manufacturing process is in the mixing process in which mechanical stirring and heating in the trans-esterification process require more energy and a longer time. A higher and stronger mixing process is required to increase the contact area between the two phases of the mixed substance to produce the emulsion. Ultrasonic is a tool that can be useful for a liquid mixing process that tends to be separated. Ultrasonic waves can cause mixing intensity at the micro level and increase mass transfer, so the reaction can be performed at a much faster rate. This study is to figure out the effect of ultrasonic irradiation on the transesterification process of biodiesel from Kemiri Sunan Oil.

Effects of Transition-Metal Mixing on Na Ordering and Kinetics in Layered P 2 Oxides

NASA Astrophysics Data System (ADS)

Zheng, Chen; Radhakrishnan, Balachandran; Chu, Iek-Heng; Wang, Zhenbin; Ong, Shyue Ping

2017-06-01

Layered P 2 oxides are promising cathode materials for rechargeable sodium-ion batteries. In this work, we systematically investigate the effects of transition-metal (TM) mixing on Na ordering and kinetics in the NaxCo1 -yMnyO2 model system using density-functional-theory (DFT) calculations. The DFT-predicted 0-K stability diagrams indicate that Co-Mn mixing reduces the energetic differences between Na orderings, which may account for the reduction of the number of phase transformations observed during the cycling of mixed-TM P 2 layered oxides compared to a single TM. Using ab initio molecular-dynamics simulations and nudged elastic-band calculations, we show that the TM composition at the Na(1) (face-sharing) site has a strong influence on the Na site energies, which in turn impacts the kinetics of Na diffusion towards the end of the charge. By employing a site-percolation model, we establish theoretical upper and lower bounds for TM concentrations based on their effect on Na(1) site energies, providing a framework to rationally tune mixed-TM compositions for optimal Na diffusion.

Thermal fluids for CSP systems: Alkaline nitrates/nitrites thermodynamics modelling method

NASA Astrophysics Data System (ADS)

Tizzoni, A. C.; Sau, S.; Corsaro, N.; Giaconia, A.; D'Ottavi, C.; Licoccia, S.

2016-05-01

Molten salt (MS) mixtures are used for the transport (HTF-heat transfer fluid) and storage of heat (HSM-heat storage material) in Concentration Solar Plants (CSP). In general, alkaline and earth-alkaline nitrate/nitrite mixtures are employed. Along with its upper stability temperature, the melting point (liquidus point) of a MS mixture is one of the main parameters which defines its usefulness as a HTF and HSM medium. As a result, we would like to develop a predictive model which will allow us to forecast freezing points for different MS mixture compositions; thus circumventing the need to determine experimentally the phase diagram for each MS mixture. To model ternary/quaternary phase diagram, parameters for the binary subsystems are to be determined, which is the purpose of the concerned work. In a binary system with components A and B, in phase equilibrium conditions (e.g. liquid and solid) the chemical potentials (partial molar Gibbs energy) for each component in each phase are equal. For an ideal solution it is possible to calculate the mixing (A+B) Gibbs energy:ΔG = ΔH - TΔS = RT(xAlnxA + xBlnxB) In case of non-ideal solid/liquid mixtures, such as the nitrates/nitrites compositions investigated in this work, the actual value will differ from the ideal one by an amount defined as the "mixing" (mix) Gibbs free energy. If the resulting mixtures is assumed, as indicated in the previous literature, to follow a "regular solution" model, where all the non-ideality is considered included in the enthalpy of mixing value and considering, for instance, the A component:Δ G ≡0 =(Δ HA-T Δ SA)+(ΔH¯ m i x AL-T ΔS¯ m i x AL)-(ΔH¯ m i x AS-T ΔS¯ m i x AS)where the molar partial amounts can be calculated from the total value by the Gibbs Duhem equation: (ΔH¯m i x AL=ΔHm i x-XB Ld/Δ Hm i x d XB L ) L;(ΔH¯m i x AS=ΔHm i x-XB Sd/Δ Hm i x d XB S ) S and, in general, it is possible to express the mixing enthalpy for solids and liquids as a function of the mol fraction: Δ HL m i x=XA LXB L(a1+b1XA L+c1XA LXB L),Δ HS m i x=XA SXB S(a2+b2XA S+c2XA SXB S) From the latter expressions it can be possible to modelize the phase diagram of a binary mixtures by using the a,b and c couples of parameters. To calculate those coefficients a method commonly employed in literature is to measure the mixing enthalpies, or to use one reported of the enthalpy of mixing (for instance for the liquid state) and calculate the other one using the phase diagram points. A direct ΔHmix (in solid or liquid phase) measurement can be difficult to carry out using common DSC equipment generally present in research laboratories. In fact, such determinations can be, in principle, performed, but the obtained data will be affected by large experimental errors. On the other hand, it is possible to obtain values with great precision regarding the algebraic sum of mixing enthalpies and the phase diagram trend. For this reason, only the phase diagrams are proposed to be used to calculate a, b, c parameters, and, subsequently, the total (liquid-solid algebraic sum) enthalpy of mixing will be employed to verify their validity. At this aim, a C++ code was assessed and used. Three binary mixtures were considered by combining NaNO3, KNO3 and NaNO2.

Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach.

PubMed

Arrieta, Jorge; Cartwright, Julyan H E; Gouillart, Emmanuelle; Piro, Nicolas; Piro, Oreste; Tuval, Idan

2015-01-01

Mixing fluid in a container at low Reynolds number--in an inertialess environment--is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the "belly phase," peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing.

Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach

PubMed Central

Arrieta, Jorge; Cartwright, Julyan H. E.; Gouillart, Emmanuelle; Piro, Nicolas; Piro, Oreste; Tuval, Idan

2015-01-01

Mixing fluid in a container at low Reynolds number— in an inertialess environment—is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the “belly phase,” peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing. PMID:26154384

Three-dimensional concentration mapping of organic blends

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

Roehling, John D.; Batenburg, Kees J.; Swain, F. B.

2013-05-06

We quantitatively measure the three-dimensional morphology of mixed organic layers using high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) with electron tomography for the first time. The mixed organic layers used for organic photovoltaic applications have not been previously imaged using STEM tomography as there is insufficient contrast between donor and acceptor components. We generate contrast by substituting fullerenes with endohedral fullerenes that contain a Lu3N cluster within the fullerene cage. The high contrast and signal-to-noise ratio, in combination with use of the discrete algebraic reconstruction technique (DART), allowed us to generate the most detailed and accurate three-dimensional map ofmore » BHJ morphology to date. From the STEM tomography reconstructions we determined that three distinct material phases are present within the BHJs. By observation of the changes to morphology and mixing ratio that occur during thermal and solvent annealing, we are able to determine how mutual solubility and fullerene crystallization affect the formation of morphology and long term stability of the material mixture. This material/technique combination shows itself as a powerful tool for examining morphology in detail and allows for observation of nanoscopic changes in local concentration. This research was supported in part by Laboratory Directed Research & Development program at PNNL. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy under contract DE-AC05-76RL01830.« less

Effect of mixing techniques on bacterial attachment and disinfection time of polyether impression material

PubMed Central

Guler, Umut; Budak, Yasemin; Ruh, Emrah; Ocal, Yesim; Canay, Senay; Akyon, Yakut

2013-01-01

Objective: The aim of this study was 2-fold. The first aim was to evaluate the effects of mixing technique (hand-mixing or auto-mixing) on bacterial attachment to polyether impression materials. The second aim was to determine whether bacterial attachment to these materials was affected by length of exposure to disinfection solutions. Materials and Methods: Polyether impression material samples (n = 144) were prepared by hand-mixing or auto-mixing. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were used in testing. After incubation, the bacterial colonies were counted and then disinfectant solution was applied. The effect of disinfection solution was evaluated just after the polymerization of impression material and 30 min after polymerization. Differences in adherence of bacteria to the samples prepared by hand-mixing and to those prepared by auto-mixing were assessed by Kruskal-Wallis and Mann-Whitney U-tests. For evaluating the efficiency of the disinfectant, Kruskal-Wallis multiple comparisons test was used. Results: E. coli counts were higher in hand-mixed materials (P < 0.05); no other statistically significant differences were found between hand- and auto-mixed materials. According to the Kruskal-Wallis test, significant differences were found between the disinfection procedures (Z > 2.394). Conclusion: The methods used for mixing polyether impression material did not affect bacterial attachment to impression surfaces. In contrast, the disinfection procedure greatly affects decontamination of the impression surface. PMID:24966729

New Oxide Materials for an Ultra High Temperature Environment

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

Perepezko, John H.

In this project, a new oxide material, Hf 6Ta 2O 17 has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf 6Ta 2O 17 with amore » complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf 6Ta 2O 17 superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO 2 and Ta 2O 5 and verified the low thermal conductivity of Hf 6Ta 2O 17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf 6Ta 2O 17, which shows an initial parabolic oxidation kinetics.« less

Effect of Fe3O4 addition on dielectric properties of LaFeO3 nano-crystalline materials synthesized by sol-gel method

NASA Astrophysics Data System (ADS)

Laysandra, H.; Triyono, D.

2017-04-01

Dielectric properties of nano-crystalline material LaFeO3.xFe3O4 with x = 0, 0.1, 0.2, 0.3, and 0.4 at.% have been studied by impedance spectroscopy method. LaFeO3 was synthesized by sol-gel method resulting nano-particle. Then, it was mixed with Fe3O4 powder. The mixture powder was pressed to form pellet and then sintered at 1300°C for 1 h to form nano-crystalline of LaFeO3.xFe3O4. X-ray diffraction characterization at room temperature for all samples show two phases i.e. perovskite LaFeO3 (orthorhombic) as a main phase and Fe3O4 (cubic) as second phase. It is found that the crystallite size of main phase increases with addition of Fe3O4 until 0.3 at.%. The electrical properties as a function of temperature (300-500 K) and frequency (100 Hz - 1 MHz) are presented in Nyquist and Bode plots. It is observed that from equivalent circuit and their parameters, dielectrical properties are contributed by grain and grain boundary. The dielectric constant, ε‧ were calculated by parallel plate method and their values reach up to 107 exhibiting typical colossal dielectric constant (CDC) material like behavior.

A Hybrid Nanomaterial for the Controlled Generation of Free Radicals and Oxidative Destruction of Hypoxic Cancer Cells.

PubMed

Shen, Song; Zhu, Chunlei; Huo, Da; Yang, Miaoxin; Xue, Jiajia; Xia, Younan

2017-07-17

Anticancer modalities based on oxygen free radicals, including photodynamic therapy and radiotherapy, have emerged as promising treatments in the clinic. However, the hypoxic environment in tumor tissue prevents the formation of oxygen free radicals. Here we introduce a novel strategy that employs oxygen-independent free radicals generated from a polymerization initiator for eradicating cancer cells. The initiator is mixed with a phase-change material and loaded into the cavities of gold nanocages. Upon irradiation by a near-infrared laser, the phase-change material is melted due to the photothermal effect of gold nanocages, leading to the release and decomposition of the loaded initiator to generate free radicals. The free radicals produced in this way are highly effective in inducing apoptosis in hypoxic cancer cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Opto-electronic device for frequency standard generation and terahertz-range optical demodulation based on quantum interference

DOEpatents

Georgiades, N.P.; Polzik, E.S.; Kimble, H.J.

1999-02-02

An opto-electronic system and technique for comparing laser frequencies with large frequency separations, establishing new frequency standards, and achieving phase-sensitive detection at ultra high frequencies are disclosed. Light responsive materials with multiple energy levels suitable for multi-photon excitation are preferably used for nonlinear mixing via quantum interference of different excitation paths affecting a common energy level. Demodulation of a carrier with a demodulation frequency up to 100`s THZ can be achieved for frequency comparison and phase-sensitive detection. A large number of materials can be used to cover a wide spectral range including the ultra violet, visible and near infrared regions. In particular, absolute frequency measurement in a spectrum from 1.25 {micro}m to 1.66 {micro}m for fiber optics can be accomplished with a nearly continuous frequency coverage. 7 figs.

Reconstructing the microstructure of polyimide-silicalite mixed-matrix membranes and their particle connectivity using FIB-SEM tomography.

PubMed

Diblíková, P; Veselý, M; Sysel, P; Čapek, P

2018-03-01

Properties of a composite material made of a continuous matrix and particles often depend on microscopic details, such as contacts between particles. Focusing on processing raw focused-ion beam scanning electron microscope (FIB-SEM) tomography data, we reconstructed three mixed-matrix membrane samples made of 6FDA-ODA polyimide and silicalite-1 particles. In the first step of image processing, backscattered electron (BSE) and secondary electron (SE) signals were mixed in a ratio that was expected to obtain a segmented 3D image with a realistic volume fraction of silicalite-1. Second, after spatial alignment of the stacked FIB-SEM data, the 3D image was smoothed using adaptive median and anisotropic nonlinear diffusion filters. Third, the image was segmented using the power watershed method coupled with a seeding algorithm based on geodesic reconstruction from the markers. If the resulting volume fraction did not match the target value quantified by chemical analysis of the sample, the BSE and SE signals were mixed in another ratio and the procedure was repeated until the target volume fraction was achieved. Otherwise, the segmented 3D image (replica) was accepted and its microstructure was thoroughly characterized with special attention paid to connectivity of the silicalite phase. In terms of the phase connectivity, Monte Carlo simulations based on the pure-phase permeability values enabled us to calculate the effective permeability tensor, the main diagonal elements of which were compared with the experimental permeability. In line with the hypothesis proposed in our recent paper (Čapek, P. et al. (2014) Comput. Mater. Sci. 89, 142-156), the results confirmed that the existence of particle clusters was a key microstructural feature determining effective permeability. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Investigation of the optical property and photocatalytic activity of mixed phase nanocrystalline titania

NASA Astrophysics Data System (ADS)

Paul, Susmita; Choudhury, Amarjyoti

2014-10-01

Mixed phase nanocrystalline titania are prepared by simple sol-gel method. The physico-chemical characteristics of the prepared nanoparticles are studied with X-ray diffraction, high-resolution transmission electron microscopy, RAMAN, BET, UV-Vis, steady state and time resolved photoluminescence. X-ray diffraction and Raman spectra clearly demarcate the anatase and rutile phase as both the phases give different diffraction patterns and Raman peaks. A comparison in the band gap indicates that pure anatase and rutile phase have band gap in the UV region, whereas a mixture of these phases has lower band gap and corresponds to the visible region. Steady state and time resolved photoluminescence are employed to understand the emissivity and carrier lifetime. The photocatalytic activity is evaluated by monitoring the degradation of phenol under visible light illumination. Due to the synergistic effect of mixed anatase and rutile phases, mixed phase nanocrystalline titania exhibit superior photocatalytic activity.

Experimental study on thermal storage performance of binary mixtures of fatty acids

NASA Astrophysics Data System (ADS)

Yan, Quanying; Zhang, Jing; Liu, Chao; Liu, Sha; Sun, Xiangyu

2018-02-01

We selected five kinds of fatty acids including the capric acid, stearic acid, lauric acid, palmitic acid and myristic acid and mixed them to prepare10 kinds of binary mixtures of fatty acids according to the predetermined proportion,tested the phase change temperature and latent heat of mixtures by differential scanning calorimetry(DSC). In order to find the fatty acid mixture which has suitable phase change temperature, the larger phase change latent heat and can be used for phase change wall. The results showed that the phase change temperature and latent heats of the binary mixtures of fatty acids decreased compared with the single component;The phase change temperature of the binary mixtures of fatty acids containing capric acid were lower, the range was roughly 20∼30°C,and latent heat is large,which are ideal phase change materials for phase change wall energy storage;The phase change temperature of the binary mixtures consisting of other fatty acids were still high,didn’t meet the temperature requirements of the wall energy storage.

A Review and Evaluation of the Phase Equilibria, Liquid-Phase Heats of Mixing and Excess Volumes, and Gas-Phase PVT Measurements for Nitrogen+Methane

NASA Astrophysics Data System (ADS)

Kidnay, A. J.; Miller, R. C.; Sloan, E. D.; Hiza, M. J.

1985-07-01

The available experimental data for vapor-liquid equilibria, heat of mixing, change in volume on mixing for liquid mixtures, and gas-phase PVT measurements for nitrogen+methane have been reviewed and where possible evaluated for consistency. The derived properties chosen for analysis and correlation were liquid mixture excess Gibbs free energies, and Henry's constants.

Nanostructured lipid carriers: effect of solid phase fraction and distribution on the release of encapsulated materials.

PubMed

Dan, Nily

2014-11-25

Emulsions, solid lipid nanoparticles (SLN), and nanostructured lipid carriers (NLC) containing a mix of liquid and solid domains are of interest as encapsulation vehicles for hydrophobic compounds. Studies of the release rate from these particles yield contradictory results: Some find that increasing the fraction of solid phase increases the rate of release and others the opposite. In this paper we study the release of encapsulated materials from lipid-based nanoparticles using Monte Carlo simulations. We find that, quite surprisingly, the release rate is largely insensitive to the size of solid domains or the fraction of solid phase. However, the distribution of the domains significantly affects the rate of release: Solid domains located at the interface with the surrounding solution inhibit transport, while nanoparticles where the solid domains are concentrated in the center enhance it. The latter can lead to release rates in NLCs that are faster than in the equivalent emulsions. We conclude that controlling the release rate from NLCs requires the ability to determine the location and distribution of the solid phase, which may be achieved through choice of the surfactants stabilizing the particles, incorporation of nucleation sites, and/or the cooling rates and temperatures.

Manganese in Endeavour Crater Rim Materials, Mars, and Implications for Habitability

NASA Astrophysics Data System (ADS)

Arvidson, R. E.; Catalano, J. G.; Clark, B. C.; Fischer, W. W.; Grotzinger, J. P.; Gellert, R.; Guinness, E. A.; Herkenhoff, K. E.; Johnson, J. R.; McLennan, S. M.; Ming, D. W.; Morris, R. V.; Squyres, S. W.; Yen, A. S.

2014-12-01

The Opportunity Mars rover wheels overturned two adjacent rocks and exposed underlying fracture-filling deposits while exploring the Murray Ridge rim segment of the Noachian-aged Endeavour Crater. These two small rocks, Pinnacle Island (~4 cm across) and Stuart Island (ranging from ~3 to 8 cm wide and ~10 cm long), were subsequently examined in detail to determine the textures, spectral reflectances (0.4 to 1.0 μm), and compositions of the fracture-filling materials. Relatively bright materials with a composition enriched in Mg, Fe, and S, and spectral features indicative of hydrated sulfates, are overlain with a dark, purple mineral phase or phases with a composition enriched in Mn, Ni, P, and Ca, all relative to underlying bedrock. Reflectance spectra for the dark, purple material are consistent with the presence of one or more Mn-oxide phases. Results indicate two aqueous events, one to deposit the Fe and Mg-rich sulfates, and one to deposit the Mn-rich mineral(s), perhaps with scavenging of Ni from the fluid. Ca and P-rich phases (e.g., Ca-phosphates) co-precipitated with Mn-bearing mineral(s) or were incorporated into one or more of them. Mixing of reducing ground waters with an oxidizing atmosphere or other waters likely produced both the S and Mn-enriched deposits. Oxidation of Mn, in particular, requires a very high potential oxidant relative to what is required for S or Fe oxidation. This suggests oxidation by O2 or species derived from O2. Mn-oxide phases would have provided highly favorable substrates for microbial respiration, making this period of aqueous flow through the fractures a potentially habitable environment. These results add to the evolving story of aqueous alteration of Endeavour's rim rocks, including evidence for nontronite, montmorillonite, Ca-sulfate-rich veins, and hematitic concretions.

Modeling Cloud Phase Fraction Based on In-situ Observations in Stratiform Clouds

NASA Astrophysics Data System (ADS)

Boudala, F. S.; Isaac, G. A.

2005-12-01

Mixed-phase clouds influence weather and climate in several ways. Due to the fact that they exhibit very different optical properties as compared to ice or liquid only clouds, they play an important role in the earth's radiation balance by modifying the optical properties of clouds. Precipitation development in clouds is also enhanced under mixed-phase conditions and these clouds may contain large supercooled drops that freeze quickly in contact with aircraft surfaces that may be a hazard to aviation. The existence of ice and liquid phase clouds together in the same environment is thermodynamically unstable, and thus they are expected to disappear quickly. However, several observations show that mixed-phase clouds are relatively stable in the natural environment and last for several hours. Although there have been some efforts being made in the past to study the microphysical properties of mixed-phase clouds, there are still a number of uncertainties in modeling these clouds particularly in large scale numerical models. In most models, very simple temperature dependent parameterizations of cloud phase fraction are being used to estimate the fraction of ice or liquid phase in a given mixed-phase cloud. In this talk, two different parameterizations of ice fraction using in-situ aircraft measurements of cloud microphysical properties collected in extratropical stratiform clouds during several field programs will be presented. One of the parameterizations has been tested using a single prognostic equation developed by Tremblay et al. (1996) for application in the Canadian regional weather prediction model. The addition of small ice particles significantly increased the vapor deposition rate when the natural atmosphere is assumed to be water saturated, and thus this enhanced the glaciation of simulated mixed-phase cloud via the Bergeron-Findeisen process without significantly affecting the other cloud microphysical processes such as riming and particle sedimentation rates. After the water vapor pressure in mixed-phase cloud was modified based on the Lord et al. (1984) scheme by weighting the saturation water vapor pressure with ice fraction, it was possible to simulate more stable mixed-phase cloud. It was also noted that the ice particle concentration (L>100 μm) in mixed-phase cloud is lower on average by a factor 3 and as a result the parameterization should be corrected for this effect. After accounting for this effect, the parameterized ice fraction agreed well with observed mean ice fraction.

Crystallization features of normal alkanes in confined geometry.

PubMed

Su, Yunlan; Liu, Guoming; Xie, Baoquan; Fu, Dongsheng; Wang, Dujin

2014-01-21

How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, and polymer blends, have complex molecular structures. Due to the multiple hierarchical structures and different size domains in polymer systems, confined hard environments for polymer crystallization exist widely in these materials. The confined geometry is closely related to both the phase metastability and lifetime of polymer. This affects the phase miscibility, microphase separation, and crystallization behaviors and determines both the performance of polymer materials and how easily these materials can be processed. Furthermore, the size effect of metastable states needs to be clarified in polymers. However, scientists find it difficult to propose a quantitative formula to describe the transition dynamics of metastable states in these complex systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, can provide a well-defined model system for studying the complex crystallization behaviors of polymer materials, surfactants, and lipids. Therefore, a deeper investigation of normal alkane phase behavior in confinement will help scientists to understand the crystalline phase transition and ultimate properties of many polymeric materials, especially polyolefins. In this Account, we provide an in-depth look at the research concerning the confined crystallization behavior of n-alkanes and binary mixtures in microcapsules by our laboratory and others. Since 2006, our group has developed a technique for synthesizing nearly monodispersed n-alkane containing microcapsules with controllable size and surface porous morphology. We applied an in situ polymerization method, using melamine-formaldehyde resin as shell material and nonionic surfactants as emulsifiers. The solid shell of microcapsules can provide a stable three-dimensional (3-D) confining environment. We have studied multiple parameters of these microencapsulated n-alkanes, including surface freezing, metastability of the rotator phase, and the phase separation behaviors of n-alkane mixtures using differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD), and variable-temperature solid-state nuclear magnetic resonance (NMR). Our investigations revealed new direct evidence for the existence of surface freezing in microencapsulated n-alkanes. By examining the differences among chain packing and nucleation kinetics between bulk alkane solid solutions and their microencapsulated counterparts, we also discovered a mechanism responsible for the formation of a new metastable bulk phase. In addition, we found that confinement suppresses lamellar ordering and longitudinal diffusion, which play an important role in stabilizing the binary n-alkane solid solution in microcapsules. Our work also provided new insights into the phase separation of other mixed system, such as waxes, lipids, and polymer blends in confined geometry. These works provide a profound understanding of the relationship between molecular structure and material properties in the context of crystallization and therefore advance our ability to improve applications incorporating polymeric and molecular materials.

Langmuir wave phase-mixing in warm electron-positron-dusty plasmas

NASA Astrophysics Data System (ADS)

Pramanik, Sourav; Maity, Chandan

2018-04-01

An analytical study on nonlinear evolution of Langmuir waves in warm electron-positron-dusty plasmas is presented. The massive dust grains of either positively or negatively charged are assumed to form a fixed charge neutralizing background. A perturbative analysis of the fluid-Maxwell's equations confirms that the excited Langmuir waves phase-mix and eventually break, even at arbitrarily low amplitudes. It is shown that the nature of the dust-charge as well as the amount of dust grains can significantly influence the Langmuir wave phase-mixing process. The phase-mixing time is also found to increase with the temperature.

Mixed finite element - discontinuous finite volume element discretization of a general class of multicontinuum models

NASA Astrophysics Data System (ADS)

Ruiz-Baier, Ricardo; Lunati, Ivan

2016-10-01

We present a novel discretization scheme tailored to a class of multiphase models that regard the physical system as consisting of multiple interacting continua. In the framework of mixture theory, we consider a general mathematical model that entails solving a system of mass and momentum equations for both the mixture and one of the phases. The model results in a strongly coupled and nonlinear system of partial differential equations that are written in terms of phase and mixture (barycentric) velocities, phase pressure, and saturation. We construct an accurate, robust and reliable hybrid method that combines a mixed finite element discretization of the momentum equations with a primal discontinuous finite volume-element discretization of the mass (or transport) equations. The scheme is devised for unstructured meshes and relies on mixed Brezzi-Douglas-Marini approximations of phase and total velocities, on piecewise constant elements for the approximation of phase or total pressures, as well as on a primal formulation that employs discontinuous finite volume elements defined on a dual diamond mesh to approximate scalar fields of interest (such as volume fraction, total density, saturation, etc.). As the discretization scheme is derived for a general formulation of multicontinuum physical systems, it can be readily applied to a large class of simplified multiphase models; on the other, the approach can be seen as a generalization of these models that are commonly encountered in the literature and employed when the latter are not sufficiently accurate. An extensive set of numerical test cases involving two- and three-dimensional porous media are presented to demonstrate the accuracy of the method (displaying an optimal convergence rate), the physics-preserving properties of the mixed-primal scheme, as well as the robustness of the method (which is successfully used to simulate diverse physical phenomena such as density fingering, Terzaghi's consolidation, deformation of a cantilever bracket, and Boycott effects). The applicability of the method is not limited to flow in porous media, but can also be employed to describe many other physical systems governed by a similar set of equations, including e.g. multi-component materials.

Method for low temperature preparation of a noble metal alloy

DOEpatents

Even, Jr., William R.

2002-01-01

A method for producing fine, essentially contamination free, noble metal alloys is disclosed. The alloys comprise particles in a size range of 5 to 500 nm. The method comprises 1. A method for preparing a noble metal alloy at low temperature, the method comprising the steps of forming solution of organometallic compounds by dissolving the compounds into a quantity of a compatible solvent medium capable of solvating the organometallic, mixing a portion of each solution to provide a desired molarity ratio of ions in the mixed solution, adding a support material, rapidly quenching droplets of the mixed solution to initiate a solute-solvent phase separation as the solvent freezes, removing said liquid cryogen, collecting and freezing drying the frozen droplets to produce a dry powder, and finally reducing the powder to a metal by flowing dry hydrogen over the powder while warming the powder to a temperature of about 150.degree. C.

Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

NASA Astrophysics Data System (ADS)

Sednev, I.; Menon, S.; McFarquhar, G.

2008-06-01

The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9th-10th October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors' concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and undersaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors' contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.

Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

NASA Astrophysics Data System (ADS)

Sednev, I.; Menon, S.; McFarquhar, G.

2009-07-01

The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9-10 October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors' concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and subsaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors' contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.

Fast Mix Table Construction for Material Discretization

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

Johnson, Seth R

2013-01-01

An effective hybrid Monte Carlo--deterministic implementation typically requires the approximation of a continuous geometry description with a discretized piecewise-constant material field. The inherent geometry discretization error can be reduced somewhat by using material mixing, where multiple materials inside a discrete mesh voxel are homogenized. Material mixing requires the construction of a ``mix table,'' which stores the volume fractions in every mixture so that multiple voxels with similar compositions can reference the same mixture. Mix table construction is a potentially expensive serial operation for large problems with many materials and voxels. We formulate an efficient algorithm to construct a sparse mix table inmore » $$O(\\text{number of voxels}\\times \\log \\text{number of mixtures})$$ time. The new algorithm is implemented in ADVANTG and used to discretize continuous geometries onto a structured Cartesian grid. When applied to an end-of-life MCNP model of the High Flux Isotope Reactor with 270 distinct materials, the new method improves the material mixing time by a factor of 100 compared to a naive mix table implementation.« less

Effect of mixing techniques on bacterial attachment and disinfection time of polyether impression material.

PubMed

Guler, Umut; Budak, Yasemin; Ruh, Emrah; Ocal, Yesim; Canay, Senay; Akyon, Yakut

2013-09-01

The aim of this study was 2-fold. The first aim was to evaluate the effects of mixing technique (hand-mixing or auto-mixing) on bacterial attachment to polyether impression materials. The second aim was to determine whether bacterial attachment to these materials was affected by length of exposure to disinfection solutions. Polyether impression material samples (n = 144) were prepared by hand-mixing or auto-mixing. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were used in testing. After incubation, the bacterial colonies were counted and then disinfectant solution was applied. The effect of disinfection solution was evaluated just after the polymerization of impression material and 30 min after polymerization. Differences in adherence of bacteria to the samples prepared by hand-mixing and to those prepared by auto-mixing were assessed by Kruskal-Wallis and Mann-Whitney U-tests. For evaluating the efficiency of the disinfectant, Kruskal-Wallis multiple comparisons test was used. E. coli counts were higher in hand-mixed materials (P < 0.05); no other statistically significant differences were found between hand- and auto-mixed materials. According to the Kruskal-Wallis test, significant differences were found between the disinfection procedures (Z > 2.394). The methods used for mixing polyether impression material did not affect bacterial attachment to impression surfaces. In contrast, the disinfection procedure greatly affects decontamination of the impression surface.

Terahertz scattering by two phased media with optically soft scatterers

NASA Astrophysics Data System (ADS)

Kaushik, Mayank; Ng, Brian W.-H.; Fischer, Bernd M.; Abbott, Derek

2012-12-01

Frequency dependent absorption by materials at distinct frequencies in the THz range is commonly used as spectral-fingerprints for identification and classification. For transmission measurements, the substance under study is often mixed with a transparent host material. Refractive index variations arising from the presence of impurities and inconsistencies in the sample's internal structure often cause the incident radiation to scatter. This can significantly distort the measured spectral-fingerprints. In this letter, we present a numerical approach to allay the scattering contribution in THz-TDS measurements, provided the sample's refractive index is known, and reveal the true absorption spectra for a given sample.

Use of X-ray diffraction to quantify amorphous supplementary cementitious materials in anhydrous and hydrated blended cements

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

Snellings, R., E-mail: ruben.snellings@epfl.ch; Salze, A.; Scrivener, K.L., E-mail: karen.scrivener@epfl.ch

2014-10-15

The content of individual amorphous supplementary cementitious materials (SCMs) in anhydrous and hydrated blended cements was quantified by the PONKCS [1] X-ray diffraction (XRD) method. The analytical precision and accuracy of the method were assessed through comparison to a series of mixes of known phase composition and of increasing complexity. A 2σ precision smaller than 2–3 wt.% and an accuracy better than 2 wt.% were achieved for SCMs in mixes with quartz, anhydrous Portland cement, and hydrated Portland cement. The extent of reaction of SCMs in hydrating binders measured by XRD was 1) internally consistent as confirmed through the standardmore » addition method and 2) showed a linear correlation to the cumulative heat release as measured independently by isothermal conduction calorimetry. The advantages, limitations and applicability of the method are discussed with reference to existing methods that measure the degree of reaction of SCMs in blended cements.« less

Biochemicals from food waste and recalcitrant biomass via syngas fermentation: A review.

PubMed

Wainaina, Steven; Horváth, Ilona Sárvári; Taherzadeh, Mohammad J

2018-01-01

An effective method for the production of value-added chemicals from food waste and lignocellulosic materials is a hybrid thermal-biological process, which involves gasification of the solid materials to syngas (primarily CO and H 2 ) followed by fermentation. This paper reviews the recent advances in this process. The special focus is on the cultivation methods that involve the use of single strains, defined mixed cultures and undefined mixed cultures for production of carboxylic acids and higher alcohols. A rate limiting step in these processes is the low mass transfer between the gas and the liquid phases. Therefore, novel techniques that can enhance the gas-liquid mass transfer including membrane- and trickle-bed bioreactors were discussed. Such bioreactors have shown promising results in increasing the volumetric mass transfer coefficient (k L a). High gas pressure also influences the mass transfer in certain batch processes, although the presence of impurities in the gas would impede the process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shock-wave properties and high-pressure equations of state of geophysically important materials. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Boslough, M. B.

1983-01-01

Shock wave (Hugoniot), shock temperature, and release data are presented for several geophysically important, refractory materials. A sensitive multichannel optical pyrometer was developed to measure shock temperatures (2500 to 5600 K at pressures from 48 to 117 GPa) in anorthite (CaAl2Si2O8) glass. Shock temperatures of 3750 to 6000 K at pressures from 140 to 182 GPa were measured in calcium oxide (CaO). Temperature data were used to constrain the energetics of the B1-B2 phase transition at 70 GPa in CaO, and to construct a finite strain equation of state for CaO consistent with previous Hugoniot data. The CaO equation of state was used with equation of state parameters of other oxides to construct a theoretical mixed oxide Hugoniot of anorthite, which is in agreement with new Hugoniot data above about 50 GPa, determined using experimental techniques developed. The mixed oxide model, however, overestimates the shock temperatures, and does not accurately predict measured release paths.

Ar-Ar and I-Xe Ages of Caddo County and Thermal History of IAB Iron Meteorites

NASA Technical Reports Server (NTRS)

Bogard, Donald D.; Garrison, Daniel H.; Takeda, Hiroshi

2005-01-01

Inclusions in IAB iron meteorites include non-chondritic silicate and those with more primitive chondritic silicate composition. Coarse-grained gabbroic material rich in plagioclase and diopside occurs in the Caddo County IAB iron meteorite and represents a new type of chemically differentiated, extra-terrestrial, andesitic silicate. Other parts of Caddo contain mostly andesitic material. Caddo thus exhibits petrologic characteristics of parent body metamorphism of a chondrite-like parent and inhomogeneous segregation of melts. Proposed IAB formation models include parent body partial melting and fractional crystallization or incomplete differentiation due to internal heat sources, and impact/induced melting and mixing. Benedix et al. prefer a hybrid model whereby the IAB parent body largely melted, then underwent collisional breakup, partial mixing of phases, and reassembly. Most reported 129I- Xe-129 ages of IABs are greater than 4.56 Gyr and a few are greater than or = 4.567 Gyr. These oldest ages exceed the 4.567 Gyr Pb-Pb age of Ca, Al-rich inclusions in primitive meteorites,

Use of weathered and fresh bottom ash mix layers as a subbase in road constructions: environmental behavior enhancement by means of a retaining barrier.

PubMed

Del Valle-Zermeño, R; Chimenos, J M; Giró-Paloma, J; Formosa, J

2014-12-01

The presence of neoformed cement-like phases during the weathering of non-stabilized freshly quenched bottom ash favors the development of a bound pavement material with improved mechanical properties. Use of weathered and freshly quenched bottom ash mix layers placed one over the other allowed the retention of leached heavy metals and metalloids by means of a reactive percolation barrier. The addition of 50% of weathered bottom ash to the total subbase content diminished the release of toxic species to below environmental regulatory limits. The mechanisms of retention and the different processes and factors responsible of leaching strongly depended on the contaminant under concern as well as on the chemical and physical factors. Thus, the immediate reuse of freshly quenched bottom ash as a subbase material in road constructions is possible, as both the mechanical properties and long-term leachability are enhanced. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phase Stability and Electronic Structure of Prospective Sb-Based Mixed Sulfide and Iodide 3D Perovskite (CH3NH3)SbSI2.

PubMed

Li, Tianyang; Wang, Xiaoming; Yan, Yanfa; Mitzi, David B

2018-06-29

Lead-free antimony-based mixed sulfide and iodide perovskite phases have recently been reported to be synthesized experimentally and to exhibit reasonable photovoltaic performance. Through a combination of experimental validation and computational analysis, we show no evidence of the formation of the mixed sulfide and iodide perovskite phase, MASbSI 2 (MA = CH 3 NH 3 + ), and instead that the main products are a mixture of the binary and ternary compounds (Sb 2 S 3 and MA 3 Sb 2 I 9 ). Density functional theory calculations also indicate that such a mixed sulfide and iodide perovskite phase should be thermodynamically less stable compared with binary/ternary anion-segregated secondary phases and less likely to be synthesized under equilibrium conditions. Additionally, band structure calculations show that this mixed sulfide and iodide phase, if possible to synthesize (e.g., under nonequilibrium conditions), should have a suitable direct band gap for photovoltaic application.

Bulk heterojunction morphology of polymer:fullerene blends revealed by ultrafast spectroscopy

PubMed Central

Serbenta, Almis; Kozlov, Oleg V.; Portale, Giuseppe; van Loosdrecht, Paul H. M.; Pshenichnikov, Maxim S.

2016-01-01

Morphology of organic photovoltaic bulk heterojunctions (BHJs) – a nanoscale texture of the donor and acceptor phases – is one of the key factors influencing efficiency of organic solar cells. Detailed knowledge of the morphology is hampered by the fact that it is notoriously difficult to investigate by microscopic methods. Here we all-optically track the exciton harvesting dynamics in the fullerene acceptor phase from which subdivision of the fullerene domain sizes into the mixed phase (2–15 nm) and large (>50 nm) domains is readily obtained via the Monte-Carlo simulations. These results were independently confirmed by a combination of X-ray scattering, electron and atomic-force microscopies, and time-resolved photoluminescence spectroscopy. In the large domains, the excitons are lost due to the high energy disorder while in the ordered materials the excitons are harvested with high efficiency even from the domains as large as 100 nm due to the absence of low-energy traps. Therefore, optimizing of blend nanomorphology together with increasing the material order are deemed as winning strategies in the exciton harvesting optimization. PMID:27824085

Mixed-bed ion exchange chromatography employing a salt-free pH gradient for improved sensitivity and compatibility in MudPIT.

PubMed

Mommen, Geert P M; Meiring, Hugo D; Heck, Albert J R; de Jong, Ad P J M

2013-07-16

In proteomics, comprehensive analysis of peptides mixtures necessitates multiple dimensions of separation prior to mass spectrometry analysis to reduce sample complexity and increase the dynamic range of analysis. The main goal of this work was to improve the performance of (online) multidimensional protein identification technology (MudPIT) in terms of sensitivity, compatibility and recovery. The method employs weak anion and strong cation mixed-bed ion exchange chromatography (ACE) in the first separation dimension and reversed phase chromatography (RP) in the second separation dimension (Motoyama et.al. Anal. Chem 2007, 79, 3623-34.). We demonstrated that the chromatographic behavior of peptides in ACE chromatography depends on both the WAX/SCX mixing ratio as the ionic strength of the mobile phase system. This property allowed us to replace the conventional salt gradient by a (discontinuous) salt-free, pH gradient. First dimensional separation of peptides was accomplished with mixtures of aqueous formic acid and dimethylsulfoxide with increasing concentrations. The overall performance of this mobile phase system was found comparable to ammonium acetate buffers in application to ACE chromatography, but clearly outperformed strong cation exchange for use in first dimensional peptide separation. The dramatically improved compatibility between (salt-free) ion exchange chromatography and reversed phase chromatography-mass spectrometry allowed us to downscale the dimensions of the RP analytical column down to 25 μm i.d. for an additional 2- to 3-fold improvement in performance compared to current technology. The achieved levels of sensitivity, orthogonality, and compatibility demonstrates the potential of salt-free ACE MudPIT for the ultrasensitive, multidimensional analysis of very modest amounts of sample material.

Spray and High-Pressure Flow Computations in the National Combustion Code (NCC) Improved

NASA Technical Reports Server (NTRS)

Raju, Manthena S.

2002-01-01

Sprays occur in a wide variety of industrial and power applications and in materials processing. A liquid spray is a two-phase flow with a gas as the continuous phase and a liquid as the dispersed phase in the form of droplets or ligaments. The interactions between the two phases--which are coupled through exchanges of mass, momentum, and energy--can occur in different ways at disparate time and length scales involving various thermal, mass, and fluid dynamic factors. An understanding of the flow, combustion, and thermal properties of a rapidly vaporizing spray requires careful modeling of the ratecontrolling processes associated with turbulent transport, mixing, chemical kinetics, evaporation, and spreading rates of the spray, among many other factors. With the aim of developing an efficient solution procedure for use in multidimensional combustor modeling, researchers at the NASA Glenn Research Center have advanced the state-of-the-art in spray computations in several important ways.

Microfluidic device and methods for focusing fluid streams using electroosmotically induced pressures

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2010-06-01

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either electric current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to electrokinetically inducing fluid flow to confine a selected material in a region of a microchannel that is not influenced by an electric field. Other structures for inducing fluid flow in accordance with this invention include nanochannel bridging membranes and alternating current fluid pumping devices. Applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Outstanding visible photocatalytic activity of a new mixed bismuth titanatate material

NASA Astrophysics Data System (ADS)

Zambrano, P.; Sayagués, M. J.; Navío, J. A.; Hidalgo, M. C.

2017-02-01

In this work, a new photocatalyst based on bismuth titanates with outstanding visible photocatalytic activity was prepared by a facile hydrothermal method. The synthesised material showed visible activity as high as UV activity of commercial TiO2 P25 under the same experimental conditions for phenol degradation. A wide characterisation of the photocatalyst was performed. The material was composed of three phases; majority of Bi20TiO32 closely interconnected to Bi4Ti3O12 and amorphous TiO2. The high visible activity showed by this material could be ascribed to a combination of several features; i.e. low band gap energy value (2.1 eV), a structure allowing a good separation path for visible photogenerated electron-holes pairs and a relatively high surface area. This photocatalyst appeared as a promising material for solar and visible applications of photocatalysis.

Investigation of two-phase heat transfer coefficients of argon-freon cryogenic mixed refrigerants

NASA Astrophysics Data System (ADS)

Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon

2014-11-01

Mixed refrigerant Joule Thomson refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in the heat exchanger design of mixed refrigerant Joule Thomson refrigerators, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of argon-freon mixed refrigerant are measured in a microchannel heat exchanger. A Printed Circuit Heat Exchanger (PCHE) with 340 μm hydraulic diameter has been developed as a compact microchannel heat exchanger and utilized in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic two-phase mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.

Mixed ionic-electronic conductors for electrodes of barium cerate-based SOFCS

NASA Astrophysics Data System (ADS)

Wu, Zhonglin

Gadolinium doped barium cerates (BCGs) have been identified as promising electrolyte materials for intermediate-temperature solid oxide fuel cells (SOFCs). It is crucial to develop compatible electrode materials for such electrolytes. Mixed ionic-electronic conductor (MIEC) electrode materials developed for SOFCs based on yttrium-stabilized zirconia (YSZ) may be used as electrode materials for BCG-based SOFCs; but a careful re-evaluation is required due to the intrinsic differences between BCG and YSZ. The performance of these electrode materials depends critically the transport of ionic and electronic species as well as gas. Accordingly, a profound understanding of transport in MIEC electrodes is imperative to effective design of high performance SOFCs. In this thesis, ambipolar transport in composite MIEC electrodes has been modeled using percolation theory to predict the effect of volume fractions of constituent phases and porosity on ambipolar conductivity. Transport and electrode kinetics of homogeneous MIEC electrodes have also been formulated under a steady-state condition to predict the distributions of ionic defects and current carried by each defect in such electrodes. Effects of catalytic properties, transport properties, and microstructure of porous electrodes and interfaces on the electrode performance are investigated. Under the guidelines of the theoretical modeling, several MIEC electrode materials are developed. Lasb{1-x}Srsb{x}Cosb{1-x}Fesb{y}Osb{3-delta} homogeneous materials are studied as cathode materials. However, the interfacial resistance seems too high due to the lack of catalytic activity at intermediate temperatures. Results indicate that Ag-Bisb{1.5}Ysb{0.5}Osb3 composite MIECs are good cathode materials when the volume fractions of constituent phases and porosity are carefully controlled. Such electrodes have low interfacial resistance, better binding strength, and smaller thermal mismatch with the BCG electrolyte, compared to other metal electrodes (such as Pt and Ag). Ni-BCG composite MIECs are studied as anode materials. It is found that electrodes prepared from NiO and reduced to Ni in situ is not catalytically active because of diffusion of NiO into BCG, which forms a resistive layer. Electrodes prepared from Ni metal and fired in an inert or reducing atmosphere exhibit low interfacial resistance and good compatibility with BCG electrolyte. Stability of these developed electrode materials is investigated under conditions pertinent to SOFCs.

Isotopic homogeneity of iron in the early solar nebula.

PubMed

Zhu, X K; Guo, Y; O'Nions, R K; Young, E D; Ash, R D

2001-07-19

The chemical and isotopic homogeneity of the early solar nebula, and the processes producing fractionation during its evolution, are central issues of cosmochemistry. Studies of the relative abundance variations of three or more isotopes of an element can in principle determine if the initial reservoir of material was a homogeneous mixture or if it contained several distinct sources of precursor material. For example, widespread anomalies observed in the oxygen isotopes of meteorites have been interpreted as resulting from the mixing of a solid phase that was enriched in 16O with a gas phase in which 16O was depleted, or as an isotopic 'memory' of Galactic evolution. In either case, these anomalies are regarded as strong evidence that the early solar nebula was not initially homogeneous. Here we present measurements of the relative abundances of three iron isotopes in meteoritic and terrestrial samples. We show that significant variations of iron isotopes exist in both terrestrial and extraterrestrial materials. But when plotted in a three-isotope diagram, all of the data for these Solar System materials fall on a single mass-fractionation line, showing that homogenization of iron isotopes occurred in the solar nebula before both planetesimal accretion and chondrule formation.

Determination of ultraviolet filter activity on coconut oil cosmetic cream

NASA Astrophysics Data System (ADS)

Widiyati, Eni

2017-08-01

A research on determination of ultraviolet (UV) filter activity of cosmetic cream with coconut oil as raw material has been done. The cream was made by mixing the oil phase (coconut oil, stearic acid, lanolin and cetyl alcohol) at 70°C and the water phase (glycerin, aquadest and triethanolamine) at 70°C, while stirring until reached a temperature of 35°C. It was made also a cream with inorganic sunscreen TiO2 and organic sunscreen benzophenone-3 as a comparison. To study the UV filter activity, each cream was determined the UV absorption using UV spectrophotometer. The results show that cosmetic cream with coconut oil as raw material absorbs UV rays in the region of UV-C, whereas the cream with TiO2 absorbs the UV rays from UV-C to UV-A and cream with benzophenone-3 absorbs the UV rays from UV-B to UV-A region. This means that, the cosmetic cream with coconut oil as raw material has an activity as UV-C filter. If this cream is expected to have an activity as a sunscreen, it must be added an inorganic or organic sunscreen or a mixture of both as an active materials.

Chemical and Physical Interactions of Martian Surface Material

NASA Astrophysics Data System (ADS)

Bishop, J. L.

1999-09-01

A model of alteration and maturation of the Martian surface material is described involving both chemical and physical interactions. Physical processes involve distribution and mixing of the fine-grained soil particles across the surface and into the atmosphere. Chemical processes include reaction of sulfate, salt and oxidizing components of the soil particles; these agents in the soils deposited on rocks will chew through the rock minerals forming coatings and will bind surface soils together to form duricrust deposits. Formation of crystalline iron oxide/oxyhydroxide minerals through hydrothermal processes and of poorly crystalline and amorphous phases through palagonitic processes both contribute to formation of the soil particles. Chemical and physical alteration of these soil minerals and phases contribute to producing the chemical, magnetic and spectroscopic character of the Martian soil as observed by Mars Pathfinder and Mars Global Surveyor. Minerals such as maghemite/magnetite and jarosite/alunite have been observed in terrestrial volcanic soils near steam vents and may be important components of the Martian surface material. The spectroscopic properties of several terrestrial volcanic soils containing these minerals have been analyzed and evaluated in terms of the spectroscopic character of the surface material on Mars.

Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

PubMed Central

Kolel-Veetil, Manoj K.; Keller, Teddy M.

2010-01-01

The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, α-FeSi2 and β-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR). The silicon-rich β-FeSi2 is a direct band gap material usable in light emitting diode (LED) applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM) of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe)-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.

The metabolism of aflatoxin B1 by hepatocytes isolated from rats following the in vivo administration of some xenobiotics

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

Metcalfe, S.A.; Neal, G.E.

Isolated rat hepatocytes, an intact cellular system capable of performing phase I and phase II metabolism, have been used to investigate metabolism of aflatoxin B1. These cells were found to metabolise (/sup 14/C)aflatoxin B1 to aflatoxins M1 and Q1, and to radiolabelled polar material, presumably conjugates, as analysed by h.p.l.c., t.l.c. and radioactive determination. In vivo administration of the mixed function oxidase inducers, phenobarbitone and 3-methylcholanthrene, resulted in enhanced hepatocyte phase I (microsomal) metabolism of aflatoxin B1. In contrast to metabolism of AFB1 by in vitro subcellular systems increased production of polar material (conjugated metabolites) derived from (/sup 14/C)aflatoxin B1more » was also detected in hepatocytes isolated from these pretreated animals. Formation of aflatoxin Q1 by isolated hepatocytes appeared to be mediated by cytochrome P450-linked enzymes whereas cytochrome P448-linked enzymes were apparently involved in aflatoxin M1 production. Chronic feeding of aflatoxin B1 to rats enhanced hepatocyte production of conjugated material only and did not elevate cellular cytochrome P450 levels, thus suggesting that aflatoxin B1 is not an inducer of its own primary metabolism.« less

Cd(1-x)Zn(x)O [0.05 ≤x≤ 0.26] synthesized by vapor-diffusion induced hydrolysis and co-nucleation from aqueous metal salt solutions.

PubMed

Schwenzer, Birgit; Neilson, James R; Jeffries, Stacie M; Morse, Daniel E

2011-02-14

Nanoparticulate Cd(1-x)Zn(x)O (x = 0, 0.05-0.26, 1) is synthesized in a simple two-step synthesis approach. Vapor-diffusion induced catalytic hydrolysis of two molecular precursors at low temperature induces co-nucleation and polycondensation to produce bimetallic layered hydroxide salts (M = Cd, Zn) as precursor materials which are subsequently converted to Cd(1-x)Zn(x)O at 400 °C. Unlike ternary materials prepared by standard co-precipitation procedures, all products presented here containing < 30 mol% Zn(2+) ions are homogeneous in elemental composition on the micrometre scale. This measured compositional homogeneity within the samples, as determined by energy dispersive spectroscopy and inductively coupled plasma spectroscopy, is a testimony to the kinetic control achieved by employing slow hydrolysis conditions. In agreement with this observation, the optical properties of the materials obey Vegard's Law for a homogeneous solid solution of Cd(1-x)Zn(x)O, where x corresponds to the values determined by inductively coupled plasma analysis, even though powder X-ray diffraction shows phase separation into a cubic mixed metal oxide phase and a hexagonal ZnO phase at all doping levels.

Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes

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

Indacochea, J. E.; Gattu, V. K.; Chen, X.

The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviorsmore » of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materials pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite materials made with added lanthanide and uranium oxides. These analyses show the corrosion behaviors of the alloy/ceramic composite materials are very similar to the corrosion behaviors of multi-phase alloy waste forms, and that the presence of oxide inclusions does not impact the corrosion behaviors of the alloy phases. Mixing with metallic waste streams is beneficial to lanthanide and uranium oxides in that they react with Zr in the fuel waste to form highly durable zirconates. The measured corrosion behaviors suggest properly formulated composite materials would be suitable waste forms for combined metallic and oxide waste streams generated during electrometallurgical reprocessing of spent nuclear fuel. Electrochemical methods are suitable for evaluating the durability and modeling long-term behavior of composite waste forms: the degradation model developed for metallic waste forms can be applied to the alloy phases formed in the composite and an affinity-based mineral dissolution model can be applied to the ceramic phases.« less

Amorphous Phases on the Surface of Mars

NASA Technical Reports Server (NTRS)

Rampe, E. B.; Morris, R. V.; Ruff, S. W.; Horgan, B.; Dehouck, E.; Achilles, C. N.; Ming, D. W.; Bish, D. L.; Chipera, S. J.

2014-01-01

Both primary (volcanic/impact glasses) and secondary (opal/silica, allophane, hisingerite, npOx, S-bearing) amorphous phases appear to be major components of martian surface materials based on orbital and in-situ measurements. A key observation is that whereas regional/global scale amorphous components include altered glass and npOx, local scale amorphous phases include hydrated silica/opal. This suggests widespread alteration at low water-to-rock ratios, perhaps due to snow/ice melt with variable pH, and localized alteration at high water-to-rock ratios. Orbital and in-situ measurements of the regional/global amorphous component on Mars suggests that it is made up of at least three phases: npOx, amorphous silicate (likely altered glass), and an amorphous S-bearing phase. Fundamental questions regarding the composition and the formation of the regional/global amorphous component(s) still remain: Do the phases form locally or have they been homogenized through aeolian activity and derived from the global dust? Is the parent glass volcanic, impact, or both? Are the phases separate or intimately mixed (e.g., as in palagonite)? When did the amorphous phases form? To address the question of source (local and/or global), we need to look for variations in the different phases within the amorphous component through continued modeling of the chemical composition of the amorphous phases in samples from Gale using CheMin and APXS data. If we find variations (e.g., a lack of or enrichment in amorphous silicate in some samples), this may imply a local source for some phases. Furthermore, the chemical composition of the weathering products may give insight into the formation mechanisms of the parent glass (e.g., impact glasses contain higher Al and lower Si [30], so we might expect allophane as a weathering product of impact glass). To address the question of whether these phases are separate or intimately mixed, we need to do laboratory studies of naturally altered samples made up of mixed phases (e.g., palagonite) and synthetic single phases to determine their short-range order structures and calculate their XRD patterns to use in models of CheMin data. Finally, to address the timing of the alteration, we need to study rocks on the martian surface of different ages that may contain glass (volcanic or impact) with MSL and future rovers to better understand how glass alters on the martian surface, if that alteration mechanism is universal, and if alteration spans across long periods of time or if there is a time past which unaltered glass remains.

Computational Discovery of New Materials Under Pressure

NASA Astrophysics Data System (ADS)

Zurek, Eva

The pressure variable opens the door towards the synthesis of materials with unique properties, ie. superconductivity, hydrogen storage media, high-energy density and superhard materials, to name a few. Indeed, recently superconductivity has been observed below 203 K and 103 K in samples of compressed sulfur dihydride and phosphine, respectively. Under pressure elements that would not normally combine may form stable compounds, or may mix in novel proportions. As a result using our chemical intuition developed at 1 atm to theoretically predict stable phases is bound to fail. In order to enable our search for superconducting hydrogen-rich systems under pressure, we have developed XtalOpt, an open-source evolutionary algorithm for crystal structure prediction. New advances in XtalOpt that enable the prediction of unit cells with greater complexity will be described. XtalOpt has been employed to find the most stable structures of hydrides with unique stoichiometries under pressure. The electronic structure and bonding of the predicted phases has been analyzed by detailed first-principles calculations based on density functional theory. The results of our computational experiments are helping us to build chemical and physical intuition for compressed solids.

A novel biphasic calcium phosphate derived from fish otoliths

NASA Astrophysics Data System (ADS)

Montañez-Supelano, N. D.; Sandoval-Amador, A.; Estupiñan-Durán, H. A.; Y Peña-Ballesteros, D.

2017-12-01

Calcium phosphates are bioceramics that have been widely used as bone substitutes because they encourage the formation of bone on their surface and can improve the healing of the bone. Hydroxyapatite HA (calcium/phosphorus ratio of 1.67) and tricalcium phosphate TCP (calcium/phosphorus ratio of 1.50) are the most common calcium phosphates. Natural materials have begun to be tested to make HA or TCP such as shells of cardiidae (family of mollusks) and eggshells. The calcium phosphate obtained has a high ability to precipitate apatite. In this work, the mixed phase ceramic of beta-Tri-calcium phosphate / hydroxyapatite (β-TCP/HA) was synthesized by aqueous precipitation from fish otoliths, which are monomineralic species composed of aragonite. Otoliths of the specie Plagioscion squamosissimus, commonly called the river croaker, were used. Techniques such as DRX, Raman spectroscopy and SEM-EDS were used to characterize the raw material and the obtained material. X-ray diffraction analysis revealed the presence of two crystalline phases of calcium phosphates with 86.2% crystallinity. SEM micrographs showed agglomeration of particles with porous structure and submicron particle sizes.

Quantitative relations between interaction parameter, miscibility and function in organic solar cells

NASA Astrophysics Data System (ADS)

Ye, Long; Hu, Huawei; Ghasemi, Masoud; Wang, Tonghui; Collins, Brian A.; Kim, Joo-Hyun; Jiang, Kui; Carpenter, Joshua H.; Li, Hong; Li, Zhengke; McAfee, Terry; Zhao, Jingbo; Chen, Xiankai; Lai, Joshua Lin Yuk; Ma, Tingxuan; Bredas, Jean-Luc; Yan, He; Ade, Harald

2018-03-01

Although it is known that molecular interactions govern morphology formation and purity of mixed domains of conjugated polymer donors and small-molecule acceptors, and thus largely control the achievable performance of organic solar cells, quantifying interaction-function relations has remained elusive. Here, we first determine the temperature-dependent effective amorphous-amorphous interaction parameter, χaa(T), by mapping out the phase diagram of a model amorphous polymer:fullerene material system. We then establish a quantitative `constant-kink-saturation' relation between χaa and the fill factor in organic solar cells that is verified in detail in a model system and delineated across numerous high- and low-performing materials systems, including fullerene and non-fullerene acceptors. Our experimental and computational data reveal that a high fill factor is obtained only when χaa is large enough to lead to strong phase separation. Our work outlines a basis for using various miscibility tests and future simulation methods that will significantly reduce or eliminate trial-and-error approaches to material synthesis and device fabrication of functional semiconducting blends and organic blends in general.

Toward the Characterization of Mixed-Phase Clouds Using Remote Sensing

NASA Astrophysics Data System (ADS)

Andronache, C.

2015-12-01

Mixed-phase clouds consist of a mixture of ice particles and liquid droplets at temperatures below 0 deg C. They are present in all seasons in many regions of the world, account for about 30% of the global cloud coverage, and are linked to cloud electrification and aircraft icing. The mix of ice particles, liquid droplets, and water vapor is unstable, and such clouds are thought to have a short lifetime. A characteristic parameter is the phase composition of mixed-phase clouds. It affects the cloud life cycle and the rate of precipitation. This parameter is important for cloud parameters retrievals by radar, lidar, and satellite and is relevant for climate modeling. The phase transformation includes the remarkable Wegener-Bergeron-Findeisen (WBF) process. The direction and the rate of the phase transformations depend on the local thermodynamic and microphysical properties. Cloud condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and the dynamic response of clouds to aerosols. The complexity of dynamics and microphysics involved in mixed-phase clouds requires a set of observational and modeling tools that continue to be refined. Among these techniques, the remote sensing methods provide an increasing number of parameters, covering large regions of the world. Thus, a series of studies were dedicated to stratiform mixed-phase clouds revealing longer lifetime than previously thought. Satellite data and aircraft in situ measurements in deep convective clouds suggest that highly supercooled water often occurs in vigorous continental convective storms. In this study, we use cases of convective clouds to discuss the feasibility of mixed-phase clouds characterization and potential advantages of remote sensing.

Coherent transfer of orbital angular momentum to excitons by optical four-wave mixing.

PubMed

Ueno, Y; Toda, Y; Adachi, S; Morita, R; Tawara, T

2009-10-26

We demonstrate the coherent transfer of optical orbital angular momentum (OAM) to the center of mass momentum of excitons in semiconductor GaN using a four-wave mixing (FWM) process. When we apply the optical vortex (OV) as an excitation pulse, the diffracted FWM signal exhibits phase singularities that satisfy the OAM conservation law, which remain clear within the exciton dephasing time (approximately 1ps). We also demonstrate the arbitrary control of the topological charge in the output signal by changing the OAM of the input pulse. The results provide a way of controlling the optical OAM through carriers in solids. Moreover, the time evolution of the FWM with OAM leads to the study of the closed-loop carrier coherence in materials.

Low Temperature Reactivities of Ultra-High Temperature Ceramics (Hf-X System)

DTIC Science & Technology

2006-03-01

as interacting fillers with the preceramic polymer formulations. In situ formation of the SiC phase was also evaluated as a practical approach in...silicon (reaction-bonded SiC ), which was introduced either as a powder mixed in the original composite formulation or as a subsequent infiltrant that...and their aerospace and turbine applications has led to a renewal of activities to fabricate MB 2/ SiC composites as the materials of choice, because

Extraction study on uranyl nitrate for energy applications

NASA Astrophysics Data System (ADS)

Giri, R.; Nath, G.

2017-07-01

Due to the ever-growing demand of energy nuclear reactor materials and the nuclear energy are now considered to be the most critical materials and source of energy for future era. Deposition of nuclear wastes in different industry, nuclear power sector are very much toxic in open environment which are hazardous to living being. There are different methods for extraction and reprocessing of these materials which are cost effective and tedious process. Ultrasonic assisted solvent extraction process is a most efficient and economical way for extraction of such type materials. The presence of third phase in mixing of extractants-diluent pair with aqueous phase imposes the problems in extraction of nuclear reactor materials. The appropriate solvent mixture in proper concentration is an important step in the solvent extraction process. Study of thermo-physical properties helps in selecting an optimum blend for extraction process. In the present work, the extraction of uranium with the binary mixture of Methyl Ethyl Ketone (MEK) and Kerosene was investigated and discussed with the variation of ultrasonic frequency for different temperatures. The result shows that the low frequency and low temperature is suitable environment for extraction. The extraction of uranium by this method is found to be a better result for extraction study in laboratory scale as well as industrial sector.

Study of mixed ternary transition metal ferrites as potential electrodes for supercapacitor applications

NASA Astrophysics Data System (ADS)

Bhujun, Bhamini; Tan, Michelle T. T.; Shanmugam, Anandan S.

Nanocrystallites of three mixed ternary transition metal ferrite (MTTMF) were prepared by a facile sol-gel method and adopted as electrode material for supercapacitors. The phase development of the samples was determined using Fourier transform infrared (FT-IR) and thermal gravimetric analysis (TG). X-ray diffraction (XRD) analysis revealed the formation of a single-phase spinel ferrite in CuCoFe2O4 (CuCoF), NiCoFe2O4 (NiCoF) and NiCuFe2O4 (NiCuF). The surface characteristics and elemental composition of the nanocomposites have been studied by means of field emission scanning electron microscopy (FESEM), as well as energy dispersive spectroscopy (EDS). The electrochemical performance of the nanomaterials was evaluated using a two-electrode configuration by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic technique in 1 M KOH electrolyte and was found to be in the order of: CuCoF > NiCoF > NiCuF. A maximum specific capacitance of 221 Fg-1 was obtained with CuCoF at a scan rate of 5 mV s-1. In addition to an excellent cycling stability, an energy density of 7.9 kW kg-1 was obtained at a current density of 1 Ag-1. The high electrochemical performance of the MTTMF nanocomposites obtained indicates that these materials are promising electrodes for supercapacitors.

Phase behavior of model ABC triblock copolymers

NASA Astrophysics Data System (ADS)

Chatterjee, Joon

The phase behavior of poly(isoprene-b-styrene- b-ethylene oxide) (ISO), a model ABC triblock copolymer has been studied. This class of materials exhibit self-assembly, forming a large array of ordered morphologies at length scales of 5-100 nm. The formation of stable three-dimensionally continuous network morphologies is of special interest in this study. Since these nanostructures considerably impact the material properties, fundamental knowledge for designing ABC systems have high technological importance for realizing applications in the areas of nanofabrication, nanoporous media, separation membranes, drug delivery and high surface area catalysts. A comprehensive framework was developed to describe the phase behavior of the ISO triblock copolymers at weak to intermediate segregation strengths spanning a wide range of composition. Phases were characterized through a combination of characterization techniques, including small angle x-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with previous investigations on ISO, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O70), double gyroid (Q230), alternating gyroid (Q214), hexagonal (HEX), and body-centered cubic (BCC). The phase map was found to be somewhat asymmetric around the fI = fO isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation. Strategies of blending homopolymers with ISO triblock copolymer were employed for studying the swelling properties of a lamellar state. Results demonstrate that lamellar domains swell or shrink depending upon the type of homopolymer that was mixed. The results provide insight into the chain conformation of ABC triblock copolymers, where the B blocks are completely bridged across the adjacent A and C domains. In the final part of the thesis, the swelling properties were used to study the directed assembly of ABC triblock copolymers on chemically nanopatterned surfaces.

Electric-field-induced strain contributions in morphotropic phase boundary composition of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-BaTiO{sub 3} during poling

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

Khansur, Neamul H.; Daniels, John E.; Hinterstein, Manuel

2015-12-14

The microscopic contributions to the electric-field-induced macroscopic strain in a morphotropic 0.93(Bi{sub 1/2}Na{sub 1/2}TiO{sub 3})−0.07(BaTiO{sub 3}) with a mixed rhombohedral and tetragonal structure have been quantified using full pattern Rietveld refinement of in situ high-energy x-ray diffraction data. The analysis methodology allows a quantification of all strain mechanisms for each phase in a morphotropic composition and is applicable to use in a wide variety of piezoelectric compositions. It is shown that during the poling of this material 24%, 44%, and 32% of the total macroscopic strain is generated from lattice strain, domain switching, and phase transformation strains, respectively. The resultsmore » also suggest that the tetragonal phase contributes the most to extrinsic domain switching strain, whereas the lattice strain primarily stems from the rhombohedral phase. The analysis also suggests that almost 32% of the total strain is lost or is a one-time effect due to the irreversible nature of the electric-field-induced phase transformation in the current composition. This information is relevant to on-going compositional development strategies to harness the electric-field-induced phase transformation strain of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-based lead-free piezoelectric materials for actuator applications.« less

SCM Paste Samples Exposed To Aggressive Solutions. Cementitious Barriers Partnership

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

Foster, T.

This report summarizes experimental work performed by SIMCO Technologies Inc. (SIMCO) as part of the Cementitious Barriers Partnership (CBP) project. The test series followed an experimental program dedicated to the study of ordinary Portland cement (OPC) hydrated cement pastes exposed to aggressive solutions. In the present study, the scope is extended to hydrated cement pastes incorporating supplementary cementitious materials (SCM) such as fly ash and ground granulated blast furnace slag (GGBFS). Also, the range of aggressive contact solutions was expanded. The experimental program aimed at testing aggressive contact solutions that more closely mimic the chemical composition of saltstone pore solution.more » Five different solutions, some of which incorporated high levels of carbonate and nitrate, were placed in contact with four different hydrated cement paste mixes. In all solutions, 150 mmol/L of SO 4 2– (14 400 ppm) were present. The solutions included different pH conditions and different sodium content. Two paste mixes were equivalent to Vault 1/4 and Vault 2 concrete mixes used at SRS in storage structures. Two additional paste mixes, cast at the same water-to-cement ratio and using the same cements but without SCMs, were also tested. The damage evolution in samples was monitored using ultrasonic pulse velocity (UPV) and mass measurements. After three and twelve months of exposure conditions, samples were taken out of solution containers and analyzed to perform migration tests and porosity measurements. Globally, results were in line with the previous study and confirmed that high pH may limit the formation of some deleterious phases like gypsum. In this case, ettringite may form but is not necessarily associated with damage. However, the high concentration of sodium may be associated with the formation of an AFm-like mineral called U-phase. The most significant evidences of damage were all associated with the Vault 2 paste analog. This material proved very sensitive to high pH. All measurement techniques used to monitor and evaluate damage to samples indicated significant alterations to this mix when immersed in contact solutions containing sodium hydroxide. It was hypothesized that the low cement content, combined with high silica content coming from silica fume, fly ash and GGBFS led to the presence unreacted silica. It is possible that the pozzolanic reaction of these SCMs could not be activated due to the low alkali content, a direct consequence of low cement content. In this scenario, the material end up having a lot of silica available to react upon contact with sodium hydroxide, possibly forming a gel that may be similar to the gel formed in alkali-silica reactions. This scenario needs further experimental confirmation, but it may well explain the poor behavior of mix PV2 in presence of NaOH.« less

Mixed conductivity, structural and microstructural characterization of titania-doped yttria tetragonal zirconia polycrystalline/titania-doped yttria stabilized zirconia composite anode matrices

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

Colomer, M.T., E-mail: tcolomer@icv.csic.e; Maczka, M.

2011-02-15

Taking advantage of the fact that TiO{sub 2} additions to 8YSZ cause not only the formation of a titania-doped YSZ solid solution but also a titania-doped YTZP solid solution, composite materials based on both solutions were prepared by solid state reaction. In particular, additions of 15 mol% of TiO{sub 2} give rise to composite materials constituted by 0.51 mol fraction titania-doped yttria tetragonal zirconia polycrystalline and 0.49 mol fraction titania-doped yttria stabilized zirconia (0.51TiYTZP/0.49TiYSZ). Furthermore, Y{sub 2}(Ti{sub 1-y}Zr{sub y}){sub 2}O{sub 7} pyrochlore is present as an impurity phase with y close to 1, according to FT-Raman results. Lower and highermore » additions of titania than that of 15 mol%, i.e., x=0, 5, 10, 20, 25 and 30 mol% were considered to study the evolution of 8YSZ phase as a function of the TiO{sub 2} content. Furthermore, zirconium titanate phase (ZrTiO{sub 4}) is detected when the titania content is equal or higher than 20 mol% and this phase admits Y{sub 2}O{sub 3} in solid solution according to FE-SEM-EDX. The 0.51TiYTZP/0.49TiYSZ duplex material was selected in this study to establish the mechanism of its electronic conduction under low oxygen partial pressures. In the pO{sub 2} range from 0.21 to 10{sup -7.5} atm. the conductivity is predominantly ionic and constant over the range and its value is 0.01 S/cm. The ionic plus electronic conductivity is 0.02 S/cm at 1000 {sup o}C and 10{sup -12.3} atm. Furthermore, the onset of electronic conductivity under reducing conditions exhibits a -1/4 pO{sub 2} dependence. Therefore, it is concluded that the n-type electronic conduction in the duplex material can be due to a small polaron-hopping between Ti{sup 3+} and Ti{sup 4+}. -- Graphical abstract: FE-SEM micrograph of a polished and thermal etched surface of a Ti-doped YTZP/Ti-doped YSZ composite material. Display Omitted Research highlights: {yields} Ti-doped YTZP/Ti-doped YSZ composite materials are mixed conductors under low partial pressures. {yields} From 5 mol% of TiO{sub 2}, Y{sub 2}(Ti{sub 1-y},Zr{sub y}){sub 2}O{sub 7} pyrochlore is present as a minor phase, being y close to 1 according to FT-Raman studies. {yields} The onset of the electronic conductivity under reducing conditions exhibit a -1/4 pO{sub 2} dependence. The n-type electronic conduction is due to a small polaron-hopping between Ti{sup 3+} and Ti{sup 4+}.« less

Studies on aqueous two phase polymer systems useful for partitioning of biological materials

NASA Technical Reports Server (NTRS)

Brooks, D. E.; Bamberger, S.

1982-01-01

The two phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) (PEG) are mixed above a critical concentration of a few percent provide a useful medium for the separation of biological cell subpopulations via partition between the top, PEG-rich phase and the liquid-liquid phase boundary. Interfacial tensions of such systems have been measured by the rotating drop technique and found to range between 0.1-100 micro-N/m. The tension was found to depend on the length of the tie line describing the system on a phase diagram, via a power law relationship which differed depending on the concentration of Na phosphate buffer present. The electrokinetic properties of drops of one phase suspended in the other were studied for a variety of systems. It was found that the droplet electrophoretic mobility increased monotonically with phosphate concentration and drop diameter but exhibited the opposite sign from that anticipated from phosphate partition measurements. It was possible to take advantage of these electrokinetic properties and dramatically enhance the speed of phase separation through application of relatively small electric fields.

Application of silica-supported Fe-Cu nanoparticles in the selective hydrogenation of p-dinitrobenzene to p-phenylenediamine

NASA Astrophysics Data System (ADS)

Shesterkina, A. A.; Shuvalova, E. V.; Kirichenko, O. A.; Strelkova, A. A.; Nissenbaum, V. D.; Kapustin, G. I.; Kustov, L. M.

2017-02-01

Supported bimetallic Fe-Cu/SiO2 materials are synthesized, and their catalytic activity in hydrogenation of dinitrobenzene to phenylenediamine at 145-180°C and 1.3 MPa hydrogen pressure is studied for the first time. The best results (89% selectivity toward p-phenylenediamine at complete conversion of p-dinitrobenzene) are obtained for the sample synthesized via co-deposition with subsequent calcination at 300°C. The sample contains 7% iron and 3% copper. The formation of separate phases of metal oxides (for the catalysts prepared by impregnation) and mixed bimetallic oxide phases (in case of co-deposition procedure) in calcined samples is revealed via thermoprogrammed reduction with hydrogen.

Microstructures evolution and physical properties of laser induced NbC modified nanocrystalline composites

NASA Astrophysics Data System (ADS)

Li, Jianing; Liu, Kegao; Yuan, Xingdong; Shan, Feihu; Zhang, Bolun; Wang, Zhe; Xu, Wenzhuo; Zhang, Zheng; An, Xiangchen

2017-10-01

The nanoscale quasicrystals (NQs), amorphous and ultrafine nanocrystals (UNs) modified hard composites are produced by laser cladding (LC) of the Ni60A-TiC-NbC-Sb mixed powders on the additive manufacturing (AM) TA1 titanium alloy. The LC technique is favorable to formations of icosahedral quasicrystals (I-phase) with five-fold symmetry due to its rapid cooling and solidification characteristics. The formation mechanism of this I-phase is explained here. Under the actions of NQs, amorphous and UNs, such LC composites exhibited an extremely high micro-hardness. UNs may also intertwin with amorphous, forming yarn-shape materials. This research provides essential theoretical basis to improve the quality of laser-treated composites.

Phase separation in artificial vesicles driven by light and curvature

NASA Astrophysics Data System (ADS)

Rinaldin, Melissa; Pomp, Wim; Schmidt, Thomas; Giomi, Luca; Kraft, Daniela; Physics of Life Processes Team; Soft; Bio Mechanics Collaboration; Self-Assembly in Soft Matter Systems Collaboration

The role of phase-demixing in living cells, leading to the lipid-raft hypothesis, has been extensively studied. Lipid domains of higher lipid chain order are proposed to regulate protein spatial organization. Giant Unilamellar Vesicles provide an artificial model to study phase separation. So far temperature was used to initiate the process. Here we introduce a new methodology based on the induction of phase separation by light. To this aim, the composition of the lipid membrane is varied by photo-oxidation of lipids. The control of the process gained by using light allowed us to observe vesicle shape fluctuations during phase-demixing. The presence of fluctuations near the critical mixing point resembles features of a critical process. We quantitatively analyze these fluctuations using a 2d elastic model, from which we can estimate the material parameters such as bending rigidity and surface tension, demonstrating the non-equilibrium critical behaviour. Finally, I will describe recent attempts toward tuning the membrane composition by controlling the vesicle curvature.

Comprehensive insights into the structural and chemical changes in mixed-anion FeOF electrodes by using operando PDF and NMR spectroscopy.

PubMed

Wiaderek, Kamila M; Borkiewicz, Olaf J; Castillo-Martínez, Elizabeth; Robert, Rosa; Pereira, Nathalie; Amatucci, Glenn G; Grey, Clare P; Chupas, Peter J; Chapman, Karena W

2013-03-13

In-depth analysis of operando X-ray pair distribution function (PDF) data is combined with Li NMR spectroscopy to gain comprehensive insights into the electrochemical reaction mechanism of high-performance iron oxyfluoride electrodes. While the full discharge capacity could be recovered upon charge, implying reversibility of the electrochemical reaction, the atomic structure of the electrode formed after cycling (discharge-charge) differs from the pristine uncycled electrode material. Instead, the "active" electrode that forms upon cycling is a nanocomposite of an amorphous rutile phase and a nanoscale rock salt phase. Bond valence sum analysis, based on the precise structural parameters (bond lengths and coordination number) extracted from the in situ PDF data, suggests that anion partitioning occurs during the electrochemical reaction, with the rutile phase being F-rich and the rock salt phase being O-rich. The F- and O-rich phases react sequentially; Fe in a F-rich environment reacts preferentially during both discharge and charge.

Droplet microfluidics with a nanoemulsion continuous phase.

PubMed

Gu, Tonghan; Yeap, Eunice W Q; Somasundar, Ambika; Chen, Ran; Hatton, T Alan; Khan, Saif A

2016-07-05

We present the first study of a novel, generalizable method that uses a water-in-oil nanoemulsion as the continuous phase to generate uniform aqueous micro-droplets in a capillary-based microfluidic system. We first study the droplet generation mechanism in this system and compare it to the more conventional case where a simple oil/solvent (with surfactant) is used as the continuous phase. Next, we present two versatile methods - adding demulsifying chemicals and heat treatment - to allow active online chemical interaction between the continuous and dispersed phases. These methods allow each generated micro-droplet to act as a well-mixed micro-reactor with walls that are 'permeable' to the nanoemulsion droplets and their contents. Finally, we demonstrate an application of this system in the fabrication of uniform hydrogel (alginate) micro-beads with control over particle properties such as size and swelling. Our work expands the toolbox of droplet-based microfluidics, enabling new opportunities and applications involving active colloidal continuous phases carrying chemical payloads, both in advanced materials synthesis and droplet-based screening and diagnostic methods.

In situ X-Ray Diffraction of Shock-Compressed Fused Silica

NASA Astrophysics Data System (ADS)

Tracy, Sally June; Turneaure, Stefan J.; Duffy, Thomas S.

2018-03-01

Because of its widespread applications in materials science and geophysics, SiO2 has been extensively examined under shock compression. Both quartz and fused silica transform through a so-called "mixed-phase region" to a dense, low compressibility high-pressure phase. For decades, the nature of this phase has been a subject of debate. Proposed structures include crystalline stishovite, another high-pressure crystalline phase, or a dense amorphous phase. Here we use plate-impact experiments and pulsed synchrotron x-ray diffraction to examine the structure of fused silica shock compressed to 63 GPa. In contrast to recent laser-driven compression experiments, we find that fused silica adopts a dense amorphous structure at 34 GPa and below. When compressed above 34 GPa, fused silica transforms to untextured polycrystalline stishovite. Our results can explain previously ambiguous features of the shock-compression behavior of fused silica and are consistent with recent molecular dynamics simulations. Stishovite grain sizes are estimated to be ˜5 - 30 nm for compression over a few hundred nanosecond time scale.

Phase change thermal energy storage methods for combat vehicles, phase 1

NASA Astrophysics Data System (ADS)

Lynch, F. E.

1986-06-01

Three alternative cooling methods, based on latent heat absorption during phase changes, were studied for potential use in combat vehicle microclimate temperature control. Metal hydrides absorb heat as they release hydrogen gas. Plastic crystals change from one solid phase to another, absorbing heat in the process. Liquid air boils at cryogenic temperature and absorbs additional sensible heat as the cold gas mixes with the microclimate air flow. System designs were prepared for each of the three microclimate cooling concepts. These designs provide details about the three phase change materials, their containers and the auxiliary equipment needed to implement each option onboard a combat vehicle. The three concepts were compared on the basis of system mass, system volume and the energy required to regenerate them after use. Metal hydrides were found to be the lightest and smallest option by a large margin. The energy needed to regenerate a hydride thermal storage system can be extracted from the vehicle's exhaust gases.

Fast mix table construction for material discretization

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

Johnson, S. R.

2013-07-01

An effective hybrid Monte Carlo-deterministic implementation typically requires the approximation of a continuous geometry description with a discretized piecewise-constant material field. The inherent geometry discretization error can be reduced somewhat by using material mixing, where multiple materials inside a discrete mesh voxel are homogenized. Material mixing requires the construction of a 'mix table,' which stores the volume fractions in every mixture so that multiple voxels with similar compositions can reference the same mixture. Mix table construction is a potentially expensive serial operation for large problems with many materials and voxels. We formulate an efficient algorithm to construct a sparse mixmore » table in O(number of voxels x log number of mixtures) time. The new algorithm is implemented in ADVANTG and used to discretize continuous geometries onto a structured Cartesian grid. When applied to an end-of-life MCNP model of the High Flux Isotope Reactor with 270 distinct materials, the new method improves the material mixing time by a factor of 100 compared to a naive mix table implementation. (authors)« less

Methods and apparatus for handling or treating particulate material

NASA Technical Reports Server (NTRS)

Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

2009-01-01

An improved draft tube spout fluid bed (DTSFB) mixing, handling, conveying, and treating apparatus and systems, and methods for operating are provided. The apparatus and systems can accept particulate material and pneumatically or hydraulically conveying the material to mix and/or treat the material. In addition to conveying apparatus, a collection and separation apparatus adapted to receive the conveyed particulate material is also provided. The collection apparatus may include an impaction plate against which the conveyed material is directed to improve mixing and/or treatment. The improved apparatus are characterized by means of controlling the operation of the pneumatic or hydraulic transfer to enhance the mixing and/or reacting by controlling the flow of fluids, for example, air, into and out of the apparatus. The disclosed apparatus may be used to mix particulate material, for example, mortar; react fluids with particulate material; coat particulate material, or simply convey particulate material.

Evolution of microbial dynamics during the maturation phase of the composting of different types of waste.

PubMed

Villar, Iria; Alves, David; Garrido, Josefina; Mato, Salustiano

2016-08-01

During composting, facilities usually exert greater control over the bio-oxidative phase of the process, which uses a specific technology and generally has a fixed duration. After this phase, the material is deposited to mature, with less monitoring during the maturation phase. While there has been considerable study of biological parameters during the thermophilic phase, there is less research on the stabilization and maturation phase. This study evaluates the effects of the type of starting material on the evolution of microbial dynamics during the maturation phase of composting. Three waste types were used: sludge from the fish processing industry, municipal sewage sludge and pig manure, each independently mixed with shredded pine wood as bulking agent. The composting system for each waste type comprised a static reactor with capacity of 600L for the bio-oxidative phase followed by stabilization and maturation phase in triplicate 200L boxes for 112days. Phospholipid fatty acids, enzyme activities and physico-chemical parameters were measured throughout the maturation phase. The evolution of the total microbial biomass, Gram + bacteria, Gram - bacteria, fungi and enzymatic activities (β-glucosidase, cellulase, protease, acid and alkaline phosphatase) depended significantly on the waste type (p<0.001). The predominant microbial community for each waste type remained present throughout the maturation process, indicating that the waste type determines the microorganisms that are able to develop at this stage. While fungi predominated during fish sludge maturation, manure and municipal sludge were characterized by a greater proportion of bacteria. Both the structure of the microbial community and enzymatic activities provided important information for monitoring the composting process. More attention should be paid to the maturation phase in order to optimize composting. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Role of sucrose in the heterogeneous uptake of dimethylamine by ammonium sulfate aerosol particles

NASA Astrophysics Data System (ADS)

Chu, Y.; Chan, C. K.

2016-12-01

Alkyl amines are important alkaline gases besides ammonia in the atmosphere and widely detected in both gas and particle phases. Heterogeneous uptake by pre-existing particles containing acids as well as ammonium salts is one of the major pathways of alkyl amines partitioning into aerosols. Recently, phase state of ammonium salt particles has been revealed to largely affect the degree of alkyl amines uptake. Using an electrodynamic balance coupled with Raman spectroscopy, we extend the study by investigating the alkyl amine uptake by ammonium sulfate (AS) - sucrose mixed particles, since ambient aerosols usually consist of a mixed phase of organics and inorganics. Sucrose is a surrogate of hydrophilic viscous organics that can alter the phase of AS at low relative humidity (RH) and dimethylamine (DMA) is selected for its abundance amongst alkyl amine compounds. DMA uptake occurred effectively at not only 70% RH but also RH as low as 10%, significantly below the AS crystallization point. The net uptake coefficient decreased as RH decreased for fixed initial AS - sucrose particle compositions. Interestingly, it followed a first increasing then decreasing trend as sucrose molar fraction increased from 0 to 0.5, at RH below 30%. Sucrose, albeit inert to DMA vapor, indirectly affected the interaction between DMA and AS - sucrose particles. On one hand, it absorbed water at low RH and delayed the efflorescence of AS to promote DMA uptake. On the other hand, the particle became more viscous with higher sucrose concentration and exhibited an effective mass transport barrier. Hence, the uptake of alkyl amines may occur slowly once ammonium salts are mixed with viscous organics, such as those secondary organic materials formed via the oxidation of biogenic volatile organic compounds, in the particle phase. Acknowledgment This work is supported by Research Grants Council (RGC) of Hong Kong Special Administrative Region, China (GRF 16300214). The grant from Hong Kong RGC PhD Fellowship Scheme is also gratefully acknowledged.

LSPRAY: Lagrangian Spray Solver for Applications With Parallel Computing and Unstructured Gas-Phase Flow Solvers

NASA Technical Reports Server (NTRS)

Raju, Manthena S.

1998-01-01

Sprays occur in a wide variety of industrial and power applications and in the processing of materials. A liquid spray is a phase flow with a gas as the continuous phase and a liquid as the dispersed phase (in the form of droplets or ligaments). Interactions between the two phases, which are coupled through exchanges of mass, momentum, and energy, can occur in different ways at different times and locations involving various thermal, mass, and fluid dynamic factors. An understanding of the flow, combustion, and thermal properties of a rapidly vaporizing spray requires careful modeling of the rate-controlling processes associated with the spray's turbulent transport, mixing, chemical kinetics, evaporation, and spreading rates, as well as other phenomena. In an attempt to advance the state-of-the-art in multidimensional numerical methods, we at the NASA Lewis Research Center extended our previous work on sprays to unstructured grids and parallel computing. LSPRAY, which was developed by M.S. Raju of Nyma, Inc., is designed to be massively parallel and could easily be coupled with any existing gas-phase flow and/or Monte Carlo probability density function (PDF) solver. The LSPRAY solver accommodates the use of an unstructured mesh with mixed triangular, quadrilateral, and/or tetrahedral elements in the gas-phase solvers. It is used specifically for fuel sprays within gas turbine combustors, but it has many other uses. The spray model used in LSPRAY provided favorable results when applied to stratified-charge rotary combustion (Wankel) engines and several other confined and unconfined spray flames. The source code will be available with the National Combustion Code (NCC) as a complete package.

Synthesis of Hydroxide-TiO2 Compounds with Photocatalytic Activity for Degradation of Phenol

NASA Astrophysics Data System (ADS)

Contreras-Ruiz, J. C.; Martínez-Gallegos, S.; Ordoñez, E.; González-Juárez, J. C.; García-Rivas, J. L.

2017-03-01

Photocatalytic degradation of phenol using titanium dioxide (TiO2), either alone or in combination with other materials, has been tested. Mg/Al hydrotalcites prepared by two methods using inorganic (HC) or organic (HS) chemical reagents, along with mixed oxides produced by calcination of these products (HCC and HSC), were mixed with titanium isopropoxide to obtain hydroxide-TiO2 compounds (HCC-TiO2 and HSC-TiO2) and their photocatalytic activity tested in solutions of 10 mg/L phenol at 120 min under illumination at λ UV = 254 nm with power of 4 W or 8 W. The obtained materials were characterized by various techniques, revealing that TiO2 was incorporated into the mixed oxides of the calcined hydrotalcite to form the above-mentioned compounds. The photocatalytic test results indicate that the activity of HCC-TiO2 can be attributed to increased phenol adsorption by hydrotalcite for transfer to the active photocatalytic phase of the impregnated TiO2 particles, while the better results obtained for HSC-TiO2 are due to greater catalyst impregnation on the surface of the calcined hydrotalcite, reducing the screening phenomenon and achieving HSC-TiO2 degradation of up to 21.0% at 8 W. Reuse of both compounds indicated tight combination of HCC or HSC with TiO2, since in four successive separation cycles there was little reduction of activity, being associated primarily with material loss during recovery.

A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.

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

Luke,E.; Kollias, P.

2007-08-06

The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phasemore » cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud phase in high latitudes are often hindered by the highly reflecting ice-covered ground and persistent temperature inversions. From the ground, the retrieval of mixed-phase cloud properties has been the subject of extensive research over the past 20 years using polarization lidars (e.g., Sassen et al. 1990), dual radar wavelengths (e.g., Gosset and Sauvageot 1992; Sekelsky and McIntosh, 1996), and recently radar Doppler spectra (Shupe et al. 2004). Millimeter-wavelength radars have substantially improved our ability to observe non-precipitating clouds (Kollias et al., 2007) due to their excellent sensitivity that enables the detection of thin cloud layers and their ability to penetrate several non-precipitating cloud layers. However, in mixed-phase clouds conditions, the observed Doppler moments are dominated by the highly reflecting ice crystals and thus can not be used to identify the cloud phase. This limits our ability to identify the spatial distribution of cloud phase and our ability to identify the conditions under which mixed-phase clouds form.« less

Modeling of the Wegener Bergeron Findeisen process—implications for aerosol indirect effects

NASA Astrophysics Data System (ADS)

Storelvmo, T.; Kristjánsson, J. E.; Lohmann, U.; Iversen, T.; Kirkevåg, A.; Seland, Ø.

2008-10-01

A new parameterization of the Wegener-Bergeron-Findeisen (WBF) process has been developed, and implemented in the general circulation model CAM-Oslo. The new parameterization scheme has important implications for the process of phase transition in mixed-phase clouds. The new treatment of the WBF process replaces a previous formulation, in which the onset of the WBF effect depended on a threshold value of the mixing ratio of cloud ice. As no observational guidance for such a threshold value exists, the previous treatment added uncertainty to estimates of aerosol effects on mixed-phase clouds. The new scheme takes subgrid variability into account when simulating the WBF process, allowing for smoother phase transitions in mixed-phase clouds compared to the previous approach. The new parameterization yields a model state which gives reasonable agreement with observed quantities, allowing for calculations of aerosol effects on mixed-phase clouds involving a reduced number of tunable parameters. Furthermore, we find a significant sensitivity to perturbations in ice nuclei concentrations with the new parameterization, which leads to a reversal of the traditional cloud lifetime effect.

In situ study of the factors controlling Fe, Cu and Zn scavenging during the early mixing between hydrothermal fluids and seawater

NASA Astrophysics Data System (ADS)

Cathalot, C.; Laes-Huon, A.; Pelleter, E.; Maillard, L.; Chéron, S.; Boissier, A.; Waeles, M.; Cotte, L.; Pernet-Coudrier, B.; Gayet, N.; Sarrazin, J.; Sarradin, P. M.

2016-12-01

Despite the importance of trace metals for marine ecosystems and in the global carbon cycle, dissolved metal sources in the deep ocean and their export mechanism are, today, still unconstrained. The historical view that dissolved metals are largely removed from hydrothermal plumes through precipitation of a range of iron-bearing minerals is now being challenged. Several potential mechanisms for the delivery of hydrothermally sourced metals to the open ocean have been suggested and require a thorough documentation of the early mixing processes between the hydrothermal fluids and the ambient seawater. The geochemistry of a plume, and specially the rising plume, is dictated by the nature and composition of the host rock, fluid temperature, phase separation at depth and subsurface mixing processes, and thus can vary in temperature, pH, metal and dissolved gases content between spatially close hydrothermal vents. Here, we present in situ chemical conditions during the early mixing gradient between hydrothermal fluids and seawater at the Lucky Strike site (Mid-Atlantic Ridge), using a multi proxy approach targeting both the dissolved and particulate phase and combining in situ measurements and analysis back in the lab. Indeed, in situ O2, H2S and temperature measurements were performed at a 1Hz frequency, coupled to lower frequency analysis of in situ Fe2+. In addition, particulate material filtered in situ was analyzed using Inductive Coupled Plasma - Mass Spectrometry, X-Ray Diffraction, X-Ray Fluorescence and Scanning Electron Microscopy and provided useful insights regarding the reactivity of metals during the mixing processes. Our results show different behavior within the Lucky Strike vent field. Fe and S co-precipitation through chalcopyrite formation at the newly discovered Capelinhos site seem to be the main process. At the White Caste site, on the other hand, wurzite and sphalerite precipitation seems to dominate the dilution processes, H2S being rapidly titrated with the available Zinc early in the mixing. Our results indicate a clear control by subsurface mixing processes, at a very local scale: within a single vent field, temperature outflow of the hydrothermal fluid clearly drives Cu, Fe and Zn scavenging in the particulate phase, and controlling hence the iron stability and export.

Muon spin rotation study of spin dimers on a triangular lattice in Ba3 MRu2 O9

NASA Astrophysics Data System (ADS)

Ziat, Djamel; Verrier, Aimé; Quilliam, Jeffrey; Aczel, Adam; Sinclair, Ryan; Chen, Qiang; Zhou, Haidong

The family of hexagonal perovskites, Ba3 MA2 O9 has recently been proven to be fertile ground for the discovery of new, exotic magnetic phases, including several quantum spin liquid candidates. The 6H-perovskites can also accommodate spin dimers on a triangular lattice, as in the ruthenate materials Ba3MRu2O9. We will present measurements on materials containing M3 + (M = Y, La, Lu, In), which give rise to mixed valence Ru4.5 + ions wherein the orbital and charge degrees of freedom must also be considered. In particular, muon spin rotation (µSR) experiments, have allowed us to probe the nature of the magnetically ordered ground state of these materials at low temperatures.

The viscous to brittle transition in eruptions of clay suspensions

NASA Astrophysics Data System (ADS)

Schmid, Diana; Scheu, Bettina; Wadsworth, Fabian B.; Kennedy, Ben; Jolly, Art; Dingwell, Donald B.

2017-04-01

The research is motivated by the early 2013 activity of White Island, New Zealand, which was characterized by frequent small phreatic activity through a fine grained mud rich shallow crater lake. Field observations demonstrate that the small eruptions were driven by bubble-burst events. Additionally, during the ongoing eruption, water vigorously evaporated, causing a shift in rheology of the crater lake liquid-solid suspension. Yet, the effect of water content on the eruptive behaviour of clay-bearing liquid suspensions is poorly understood. Here we investigate the influence of the solid to water ratio of the clay material erupted on the eruption characteristics. Kaolin was used as an analogue for the clay and was mixed with water in different proportions. We conducted experiments with different kaolin/water mixtures held at 120°C, in which they were decompressed from 2-4 bars to ambient conditions in a few milliseconds. During an experimental eruption, the velocity of the ejected material decreased, resulting in shifts in behaviour. Based on our experimental observations we established five different regimes that depend on the particle velocity relative to the gas velocity, and on the kaolin to water ratio of the mixture. In all experiments and for all kaolin to water ratios, regime 1 is one in which particles are ejected rapidly in an expanding high velocity gas jet. In the liquid-dominated system (low kaolin to water ratios), the jet phase evolves to the ejection of elongate fluidal structures (regime 2) and then to discrete droplets (regime 3) as the ejection velocity wanes. Contrastingly, in the solid-dominated system, the jet phase (regime 1) transitions to a mixed solid-fluid structures (regime 4) and then to individual angular ejecta (regime 5). On the basis of high speed image analysis, we establish a phase diagram separating these regimes based on kaolin/water mixing rations and the ejecta velocities observed. The dominant transition between fluidal and solid-like behaviour is a viscous to brittle transition and occurs between a kaolin mass fraction of 0.48 and 0.65, which is consistent with previous observations of the liquid and plastic rheological limits, respectively. We find that a Stokes' number balances the timescale of flow with the timescale of particle motion opposing flow. We suggest that the transition from regime 1 to regime 2 occurs when the relative velocity between the ejected material and the gas phase increases and the Stokes' number exceeds 1, leading to decoupling and shear-stresses at the ejected fluid interfaces. A capillary number characterizes the transition from elongated liquid structures (regime 2) to individual droplets (regime 3) in the liquid-dominated system when the relative velocity drops to a value at which surface tension can restore the droplets to spherical. Our results emphasize that the different rheology of muddy material exhibit different characteristic eruption styles and offers a way to classify them.

Peculiarities of physical and chemical processes of clinker formation in raw mixes with increased content of magnesium oxide in presence of barite waste

NASA Astrophysics Data System (ADS)

Novoselova, I. N.; Novosyolov, A. G.

2018-03-01

The article considers the influence of barite waste on clinker formation processes in raw mixes with the increased content of magnesium oxide. A by-product of the barite concentrate manufacture of Tolcheinskoye deposit has been used as a barite waste, its predominant content of barium sulphate BaSO4 amounts to 76,11%. The impact of BaO and SO3 has been revealed, particularly the impact of barium oxide on clinker formation processes in raw mixes with the increased content of magnesium oxide. It has been clarified that the addition of barite waste into a raw mix causes the formation of dicalcium silicate in two modifications, reduces the amount of alite and influences on the composition of tricalcium aluminate. Barium mono-alluminate is formed in the composition of the intermediate material. Solid solutions with barium oxide are formed in clinker phases. The authors have determined the saturation speed of calcium oxide in magnesium-bearing raw mixes with saturation coefficient (SC) 0,91 and 0,80 in the presence of 2 and 3% barite waste in the temperature range 1300-1450°C.

Investigation of Phase Mixing in Amorphous Solid Dispersions of AMG 517 in HPMC-AS Using DSC, Solid-State NMR, and Solution Calorimetry.

PubMed

Calahan, Julie L; Azali, Stephanie C; Munson, Eric J; Nagapudi, Karthik

2015-11-02

Intimate phase mixing between the drug and the polymer is considered a prerequisite to achieve good physical stability for amorphous solid dispersions. In this article, spray dried amorphous dispersions (ASDs) of AMG 517 and HPMC-as were studied by differential scanning calorimetry (DSC), solid-state NMR (SSNMR), and solution calorimetry. DSC analysis showed a weakly asymmetric (ΔTg ≈ 13.5) system with a single glass transition for blends of different compositions indicating phase mixing. The Tg-composition data was modeled using the BKCV equation to accommodate the observed negative deviation from ideality. Proton spin-lattice relaxation times in the laboratory and rotating frames ((1)H T1 and T1ρ), as measured by SSNMR, were consistent with the observation that the components of the dispersion were in intimate contact over a 10-20 nm length scale. Based on the heat of mixing calculated from solution calorimetry and the entropy of mixing calculated from the Flory-Huggins theory, the free energy of mixing was calculated. The free energy of mixing was found to be positive for all ASDs, indicating that the drug and polymer are thermodynamically predisposed to phase separation at 25 °C. This suggests that miscibility measured by DSC and SSNMR is achieved kinetically as the result of intimate mixing between drug and polymer during the spray drying process. This kinetic phase mixing is responsible for the physical stability of the ASD.

Ignition of deuterium-trtium fuel targets

DOEpatents

Musinski, Donald L.; Mruzek, Michael T.

1991-01-01

A method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom.

Ignition of deuterium-tritium fuel targets

DOEpatents

Musinski, D.L.; Mruzek, M.T.

1991-08-27

Disclosed is a method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom. 5 figures.

Waste Water Treatment Apparatus and Methods

NASA Technical Reports Server (NTRS)

Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor); Littman, Howard (Inventor)

2014-01-01

An improved draft tube spout fluid bed (DTSFB) mixing, handling, conveying, and treating apparatus and systems, and methods for operating are provided. The apparatus and systems can accept particulate material and pneumatically or hydraulically conveying the material to mix and/or treat the material. In addition to conveying apparatus, a collection and separation apparatus adapted to receive the conveyed particulate material is also provided. The collection apparatus may include an impaction plate against which the conveyed material is directed to improve mixing and/or treatment. The improved apparatus are characterized by means of controlling the operation of the pneumatic or hydraulic transfer to enhance the mixing and/or reacting by controlling the flow of fluids, for example, air, into and out of the apparatus. The disclosed apparatus may be used to mix particulate material, for example, mortar; react fluids with particulate material; coat particulate material, or simply convey particulate material.

Surface charge fine tuning of reversed-phase/weak anion-exchange type mixed-mode stationary phases for milder elution conditions.

PubMed

Zimmermann, Aleksandra; Horak, Jeannie; Sánchez-Muñoz, Orlando L; Lämmerhofer, Michael

2015-08-28

A series of new mixed-mode reversed-phase/weak anion-exchange (RP/WAX) phases have been synthesized by immobilization of N-undecenyl-3-α-aminotropane onto thiol-modified silica gel by thiol-ene click chemistry and subsequent introduction of acidic thiol-endcapping functionalities of different type and surface densities. Click chemistry allowed to adjust a controlled surface concentration of the RP/WAX ligand in such a way that a sufficient quantity of residual thiols remained unmodified which have been capped by thiol click with either 3-butenoic acid or allylsulfonic acid as co-ligands. In another embodiment, performic acid oxidation of N-undecenyl-3-α-aminotropane-derivatized thiol-modified silica gave a RP/WAX phase with high density of sulfonic acid end-capping groups. ζ-Potential determinations confirmed the fine-tuned pI of these mixed-mode stationary phases which was shifted from 9.5 to 8.2, 7.8, and 6.5 with 3-butenoic acid and allylsulfonic acid end-capping as well as performic acid oxidation. For acidic solutes, the co-ionic endcapping leads to strongly reduced retention times and clearly allowed elution of these analytes under lower ionic strength thus milder elution conditions. In spite of the acidic endcapping, the new mixed-mode phases maintained their hydrophobic and anion-exchange selectivity as well as their multimodal nature featuring RP and HILIC elution domains at acetonitrile percentages below and above 50%, respectively. Column classification by principal component analysis of an extended retention map in comparison to a set of polar commercial and in-house synthesized stationary phases confirmed complementarity of the new mixed-mode phases with respect to HILIC, polar RP, amino and commercial mixed-mode phases. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Aerosol partitioning in natural mixed-phase clouds

NASA Astrophysics Data System (ADS)

Henning, S.; Bojinski, S.; Diehl, K.; Ghan, S.; Nyeki, S.; Weingartner, E.; Wurzler, S.; Baltensperger, U.

2004-03-01

In situ aerosol and cloud drop microphysical measurements at a high-alpine site are used to investigate aerosol partitioning between cloud and interstitial phases in natural, mid-latitude, mixed-phase clouds. Measurements indicate a decrease in the activated aerosol fraction (FN) for particle diameters dP > 100 nm with cloud temperature from FN ~ 0.54 in summer liquid-phase clouds to FN ~ 0.08 in winter mixed-phase clouds. The latter may be attributed to the Bergeron-Findeisen mechanism whereby ice crystals grow at the expense of liquid water drops, releasing formerly activated aerosols back into the interstitial phase. This provides a means to distinguish the indirect effects of aerosols on drops and ice crystals.

Experimental and theoretical evidence of a supercritical-like transition in an organic semiconductor presenting colossal uniaxial negative thermal expansion.

PubMed

van der Lee, Arie; Roche, Gilles H; Wantz, Guillaume; Moreau, Joël J E; Dautel, Olivier J; Filhol, Jean-Sébastien

2018-04-28

Thermal expansion coefficients of most materials are usually small, typically up to 50 parts per million per kelvin, and positive, i.e. materials expand when heated. Some materials show an atypical shrinking behavior in one or more crystallographic directions when heated. Here we show that a high mobility thiophene-based organic semiconductor, BHH-BTBT , has an exceptionally large negative expansion between 95 and 295 K (-216 < α 2 = α b < -333 MK -1 ), being compensated by an even larger positive expansion in the perpendicular direction (287 < α 1 < 634 MK -1 ). It is shown that these anomalous expansivities are completely absent in C8-BTBT , a much studied organic semiconductor with a closely related molecular formula and 3D crystallographic structure. Complete theoretical characterization of BHH-BTBT using ab initio molecular dynamics shows that below ∼200 K two different α and β domains exist of which one is dominant but which dynamically exchange around and above 210 K. A supercritical-like transition from an α dominated phase to a β dominated phase is observed using DSC measurements, UV-VIS spectroscopy, and X-ray diffraction. The origin of the extreme negative and positive thermal expansion is related to steric hindrance between adjacent tilted thiophene units and strongly enhanced by attractive S···S and S···C interactions within the highly anharmonic mixed-domain phase. This material could trigger the tailoring of optoelectronic devices highly sensitive to strain and temperature.

Mixing of secondary organic aerosols versus relative humidity

PubMed Central

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin

2016-01-01

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions. PMID:27791066

Mixing of secondary organic aerosols versus relative humidity.

PubMed

Ye, Qing; Robinson, Ellis Shipley; Ding, Xiang; Ye, Penglin; Sullivan, Ryan C; Donahue, Neil M

2016-10-24

Atmospheric aerosols exert a substantial influence on climate, ecosystems, visibility, and human health. Although secondary organic aerosols (SOA) dominate fine-particle mass, they comprise myriad compounds with uncertain sources, chemistry, and interactions. SOA formation involves absorption of vapors into particles, either because gas-phase chemistry produces low-volatility or semivolatile products that partition into particles or because more-volatile organics enter particles and react to form lower-volatility products. Thus, SOA formation involves both production of low-volatility compounds and their diffusion into particles. Most chemical transport models assume a single well-mixed phase of condensing organics and an instantaneous equilibrium between bulk gas and particle phases; however, direct observations constraining diffusion of semivolatile organics into particles containing SOA are scarce. Here we perform unique mixing experiments between SOA populations including semivolatile constituents using quantitative, single-particle mass spectrometry to probe any mass-transfer limitations in particles containing SOA. We show that, for several hours, particles containing SOA from toluene oxidation resist exchange of semivolatile constituents at low relative humidity (RH) but start to lose that resistance above 20% RH. Above 40% RH, the exchange of material remains constant up to 90% RH. We also show that dry particles containing SOA from α-pinene ozonolysis do not appear to resist exchange of semivolatile compounds. Our interpretation is that in-particle diffusion is not rate-limiting to mass transfer in these systems above 40% RH. To the extent that these systems are representative of ambient SOA, we conclude that diffusion limitations are likely not common under typical ambient boundary layer conditions.

The mixing mechanism during lithiation of Si negative electrode in Li-ion batteries: an ab initio molecular dynamics study.

PubMed

Johari, Priya; Qi, Yue; Shenoy, Vivek B

2011-12-14

In order to realize Si as a negative electrode material in commercial Li-ion batteries, it is important to understand the mixing mechanism of Li and Si, and stress evolution during lithiation in Si negative electrode of Li-ion batteries. Available experiments mainly provide the diffusivity of Li in Si as an averaged property, neglecting information regarding diffusivity of Si. However, if Si can diffuse as fast as Li, the stress generated during Li diffusion can be reduced. We, therefore, studied the diffusivity of Li as well as Si atoms in the Si-anode of Li-ion battery using an ab initio molecular dynamics-based methodology. The electrochemical insertion of Li into crystalline Si prompts a crystalline-to-amorphous phase transition. We considered this situation and thus examined the diffusion kinetics of Li and Si atoms in both crystalline and amorphous Si. We find that Li diffuses faster in amorphous Si as compared to crystalline Si, while Si remains relatively immobile in both cases and generates stresses during lithiation. To further understand the mixing mechanism and to relate the structure with electrochemical mixing, we analyzed the evolution of the structure during lithiation and studied the mechanism of breaking of Si-Si network by Li. We find that Li atoms break the Si rings and chains and create ephemeral structures such as stars and boomerangs, which eventually transform to Si-Si dumbbells and isolated Si atoms in the LiSi phase. Our results are found to be in agreement with the available experimental data and provide insights into the mixing mechanism of Li and Si in Si negative electrode of Li-ion batteries.

Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

DOEpatents

Voigt, J.A.; Sipola, D.L.; Tuttle, B.A.; Anderson, M.T.

1999-06-01

A process is disclosed for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications. 4 figs.

Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

DOEpatents

Voigt, James A.; Sipola, Diana L.; Tuttle, Bruce A.; Anderson, Mark T.

1999-01-01

A process for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications.

The durability of concrete containing a high-level of fly ash or a ternary blend of supplementary cementing materials

NASA Astrophysics Data System (ADS)

Gilbert, Christine M.

The research for this study was conducted in two distinct phases as follows: Phase 1: The objective was to determine the effect of fly ash on the carbonation of concrete. The specimens made for this phase of the study were larger in size than those normally used in carbonation studies and were are meant to more accurately reflect real field conditions. The results from early age carbonation testing indicate that the larger size specimens do not have a measured depth of carbonation as great as that of the smaller specimens typically used in carbonation studies at the same age and under the same conditions. Phase 2: The objective was to evaluate the performance of ternary concrete mixes containing a ternary cement blend consisting of Portland cement, slag and Type C fly ash. It was found that concrete mixtures containing the fly ash with the lower calcium (CaO) content (in binary or ternary blends) provided superior durability performance and resistance to ASR compared to that of the fly ash with the higher CaO content. Ternary blends (regardless of the CaO content of the fly ash) provided better overall durability performance than binary blends of cementing materials or the control.

Traditional Portland cement and MgO-based cement: a promising combination?

NASA Astrophysics Data System (ADS)

Tonelli, Monica; Martini, Francesca; Calucci, Lucia; Geppi, Marco; Borsacchi, Silvia; Ridi, Francesca

2017-06-01

MgO/SiO2 cements are materials potentially very useful for radioactive waste disposal, but knowledge about their physico-chemical properties is still lacking. In this paper we investigated the hydration kinetics of cementitious formulations prepared by mixing MgO/SiO2 and Portland cement in different proportions and the structural properties of the hydrated phases formed in the first month of hydration. In particular, the hydration kinetics was investigated by measuring the free water index on pastes by means of differential scanning calorimetry, while the structural characterization was carried out by combining thermal (DTA), diffractometric (XRD), and spectroscopic (FTIR, 29Si solid state NMR) techniques. It was found that calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) gels mainly form as separate phases, their relative amount and structural characteristics depending on the composition of the hydrated mixture. Moreover, the composition of the mixtures strongly affects the kinetics of hydration and the pH of the aqueous phase in contact with the cementitious materials. The results here reported show that suitable mixtures of Portland cement and MgO/SiO2 could be used to modify the properties of hydrated phases with potential application in the storage of nuclear waste in clayey disposal.

Characteristics of phase-change materials containing oxide nano-additives for thermal storage.

PubMed

Teng, Tun-Ping; Yu, Chao-Chieh

2012-11-06

In this study, the authors report the production of nanocomposite-enhanced phase-change materials (NEPCMs) using the direct-synthesis method by mixing paraffin with alumina (Al2O3), titania (TiO2), silica (SiO2), and zinc oxide (ZnO) as the experimental samples. Al2O3, TiO2, SiO2, and ZnO were dispersed into three concentrations of 1.0, 2.0, and 3.0 wt.%. Through heat conduction and differential scanning calorimeter experiments to evaluate the effects of varying concentrations of the nano-additives on the heat conduction performance and thermal storage characteristics of NEPCMs, their feasibility for use in thermal storage was determined. The experimental results demonstrate that TiO2 is more effective than the other additives in enhancing both the heat conduction and thermal storage performance of paraffin for most of the experimental parameters. Furthermore, TiO2 reduces the melting onset temperature and increases the solidification onset temperature of paraffin. This allows the phase-change heat to be applicable to a wider temperature range, and the highest decreased ratio of phase-change heat is only 0.46%, compared to that of paraffin. Therefore, this study demonstrates that TiO2, added to paraffin to form NEPCMs, has significant potential for enhancing the thermal storage characteristics of paraffin.

Simultaneous separation and analysis of water- and fat-soluble vitamins on multi-modal reversed-phase weak anion exchange material by HPLC-UV.

PubMed

Dabre, Romain; Azad, Nazanin; Schwämmle, Achim; Lämmerhofer, Michael; Lindner, Wolfgang

2011-04-01

Several methods for the separation of vitamins on HPLC columns were already validated in the last 20 years. However, most of the techniques focus on separating either fat- or water-soluble vitamins and only few methods are intended to separate lipophilic and hydrophilic vitamins simultaneously. A mixed-mode reversed-phase weak anion exchange (RP-WAX) stationary phase was developed in our laboratory in order to address such mixture of analytes with different chemical characteristics, which are difficult to separate on standard columns. The high versatility in usage of the RP-WAX chromatographic material allowed a baseline separation of ten vitamins within a single run, seven water-soluble and three fat-soluble, using three different chromatographic modes: some positively charged vitamins are eluted in ion exclusion and ion repulsion modes whereas the negatively charged molecules are eluted in the ion exchange mechanism. The non-charged molecules are eluted in a classical reversed-phase mode, regarding their polarities. The method was validated for the vitamin analysis in tablets, evaluating selectivity, robustness, linearity, accuracy, and precision. The validated method was finally employed for the analysis of the vitamin content of some commercially available supplement tablets. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Suppression of phase mixing in drift-kinetic plasma turbulence

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

Parker, J. T., E-mail: joseph.parker@stfc.ac.uk; OCIAM, Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford OX2 6GG; Brasenose College, Radcliffe Square, Oxford OX1 4AJ

2016-07-15

Transfer of free energy from large to small velocity-space scales by phase mixing leads to Landau damping in a linear plasma. In a turbulent drift-kinetic plasma, this transfer is statistically nearly canceled by an inverse transfer from small to large velocity-space scales due to “anti-phase-mixing” modes excited by a stochastic form of plasma echo. Fluid moments (density, velocity, and temperature) are thus approximately energetically isolated from the higher moments of the distribution function, so phase mixing is ineffective as a dissipation mechanism when the plasma collisionality is small.

The delayed-detonation model of Type Ia supernovae. 2: The detonation phase

NASA Technical Reports Server (NTRS)

Arnett, David; Livne, Eli

1994-01-01

The investigation, by use of two-dimensional numerical hydrodynamics simulations, of the 'delayed detonation' mechanism of Khokhlov for the explosion of Type Ia supernovae is continued. Previously we found that the deflagration is insufficient to unbind the star. Expansion shuts off the flame; much of this small production of iron group nuclei occurs at lower densities, which reduces the electron-capture problem. Because the degenerate star has an adiabatic exponent only slightly above 4/3, the energy released by deflagration drives a pulsation of large amplitude. During the first expansion phase, adiabatic cooling shuts off the burning, and a Rayleigh-Taylor instability then gives mixing of high-entropy ashes with low-entropy fuel. During the first contraction phase, compressional heating reignites the material. The burning was allowed to develop into a detonation in these nonspherical models. The detonation grows toward spherical symmetry at late times. At these densities (rho approx. 10(exp 7) to 10(exp 8) g cm(exp -3)), either Ni-56 or nuclei of the Si-Ca group are the dominant products of the burning. The bulk yields are sensitive to the density of the star when the transition to detonation occurs. The relevance of the abundances, velocities, mixing, and total energy release to the theory and interpretation of Type Ia supernovae is discussed.

Polymer composites and porous materials prepared by thermally induced phase separation and polymer-metal hybrid methods

NASA Astrophysics Data System (ADS)

Yoon, Joonsung

The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and phthalic anhydride. A simple method to prepare composite surfaces that can change the wettability in response to the temperature change was proposed and evaluated. Composite surfaces prepared by nanoporous alumina templates filled with polymers showed surface morphology and wettability that depend on temperature. This effect is attributed to the significant difference in thermal conductivity and the thermal expansion coefficient between the alumina and the polymers. The reversibility in thermal response depends on the properties of the polymers.

Effect of Cu Doping on the Structural and Electrochemical Performance of LiNi1/3Co1/3Mn1/3O2 Cathode Materials

NASA Astrophysics Data System (ADS)

Yang, Li; Ren, Fengzhagn; Feng, Qigao; Xu, Guangri; Li, Xiaobo; Li, Yuanchao; Zhao, Erqing; Ma, Jignjign; Fan, Shumin

2018-04-01

The structural and electrochemical performance of Cu-doped, Li[Ni1/3-xCo1/3 Mn1/3Cux]O2 (x = 0-0.1) cathode materials obtained by means of the sol-gel method are discussed; we used critic acid as gels and spent mixed batteries as the raw materials. The effects of the sintering time, sintering temperature, and Cu doping ratio on the phase structure, morphology, and element composition and the behavior in a galvanostatical charge/discharge test have been systemically studied. The results show that the Cu-doped material exhibits better galvanostatic charge/discharge cycling performance. At 0.2 C, its original discharge specific capacity is 180.4 mAh g-1 and its Coulomb efficiency is 90.3%. The Cu-doped material demonstrate an outstanding specific capacity at 0.2 C, 0.5 C, and 2.0 C. In comparison with the original capacities of 178 mAh g-1, 159.5 mAh g-1, and 119.4 mAh g-1, the discharge capacity after 50 cycles is 160.8 mAh g-1, 143.4 mAh g-1, and 90.1 mAh g-1, respectively. This obvious improvement relative to bare Li[Ni1/3Co1/3Mn1/3]O2 cathode materials arises from an enlarged Li layer spacing and a reduced degree of cation mixing. Therefore, Cu-doped cathode materials have obvious advantages in the field of lithium-ion batteries and their applications.

Effect of Cu Doping on the Structural and Electrochemical Performance of LiNi1/3Co1/3Mn1/3O2 Cathode Materials

NASA Astrophysics Data System (ADS)

Yang, Li; Ren, Fengzhagn; Feng, Qigao; Xu, Guangri; Li, Xiaobo; Li, Yuanchao; Zhao, Erqing; Ma, Jignjign; Fan, Shumin

2018-07-01

The structural and electrochemical performance of Cu-doped, Li[Ni1/3-xCo1/3 Mn1/3Cux]O2 ( x = 0-0.1) cathode materials obtained by means of the sol-gel method are discussed; we used critic acid as gels and spent mixed batteries as the raw materials. The effects of the sintering time, sintering temperature, and Cu doping ratio on the phase structure, morphology, and element composition and the behavior in a galvanostatical charge/discharge test have been systemically studied. The results show that the Cu-doped material exhibits better galvanostatic charge/discharge cycling performance. At 0.2 C, its original discharge specific capacity is 180.4 mAh g-1 and its Coulomb efficiency is 90.3%. The Cu-doped material demonstrate an outstanding specific capacity at 0.2 C, 0.5 C, and 2.0 C. In comparison with the original capacities of 178 mAh g-1, 159.5 mAh g-1, and 119.4 mAh g-1, the discharge capacity after 50 cycles is 160.8 mAh g-1, 143.4 mAh g-1, and 90.1 mAh g-1, respectively. This obvious improvement relative to bare Li[Ni1/3Co1/3Mn1/3]O2 cathode materials arises from an enlarged Li layer spacing and a reduced degree of cation mixing. Therefore, Cu-doped cathode materials have obvious advantages in the field of lithium-ion batteries and their applications.

Behavior of neutral solutes in pressurized flow driven electrochromatography using a mixed stationary phase of ODS and anion-exchange.

PubMed

Kitagawa, Shinya; Tsuda, Takao

2003-05-02

The behavior of neutral sample solutes in pressurized flow driven electrochromatography using a mixed stationary phase, which consisted of ODS and anion-exchange (ODS-SAX), was studied. Applications of both positive and negative voltage on a column induced increases in retention factors of sample solutes. The direction of an electroosmotic flow under applications of positive and negative voltage were the same, therefore, the sign of the surface charge density under positive and negative voltage was opposite. We proposed a new equation for the relationship between applied voltage and surface charge density, and the practical electroosmotic flow conformed to this equation. Studying the electroosmotic flow using our proposed equation revealed that the applied negative voltage accelerates the protonation of the quaternary ammonium group and dissociation of the silanol group on packing materials. The retention behavior of a neutral solute was affected by the existence of the charged functional groups. We propose that this phenomenon is applicable to the control of the retention behavior of a sample solute using an electric field.

Lithium alloy negative electrodes

NASA Astrophysics Data System (ADS)

Huggins, Robert A.

The 1996 announcement by Fuji Photo Film of the development of lithium batteries containing convertible metal oxides has caused a great deal of renewed interest in lithium alloys as alternative materials for use in the negative electrode of rechargeable lithium cells. The earlier work on lithium alloys, both at elevated and ambient temperatures is briefly reviewed. Basic principles relating thermodynamics, phase diagrams and electrochemical properties under near-equilibrium conditions are discussed, with the Li-Sn system as an example. Second-phase nucleation, and its hindrance under dynamic conditions plays an important role in determining deviations from equilibrium behavior. Two general types of composite microstructure electrodes, those with a mixed-conducting matrix, and those with a solid electrolyte matrix, are discussed. The Li-Sn-Si system at elevated temperatures, and the Li-Sn-Cd at ambient temperatures are shown to be examples of mixed-conducting matrix microstructures. The convertible oxides are an example of the solid electrolyte matrix type. Although the reversible capacity can be very large in this case, the first cycle irreversible capacity required to convert the oxides to alloys may be a significant handicap.

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.

Toxicity of electronic waste leachates to Daphnia magna: screening and toxicity identification evaluation of different products, components, and materials.

PubMed

Lithner, Delilah; Halling, Maja; Dave, Göran

2012-05-01

Electronic waste has become one of the fastest growing waste problems in the world. It contains both toxic metals and toxic organics. The aim of this study was to (1) investigate to what extent toxicants can leach from different electronic products, components, and materials into water and (2) identify which group of toxicants (metals or hydrophobic organics) that is causing toxicity. Components from five discarded electronic products (cell phone, computer, phone modem, keyboard, and computer mouse) were leached in deionised water for 3 days at 23°C in concentrations of 25 g/l for metal components, 50 g/l for mixed-material components, and 100 g/l for plastic components. The water phase was tested for acute toxicity to Daphnia magna. Eighteen of 68 leachates showed toxicity (with immobility of D. magna ≥ 50% after 48 h) and came from metal or mixed-material components. The 8 most toxic leachates, with 48 h EC(50)s ranging from 0.4 to 20 g/l, came from 2 circuit sheets (key board), integrated drive electronics (IDE) cable clips (computer), metal studs (computer), a circuit board (computer mouse), a cord (phone modem), mixed parts (cell phone), and a circuit board (key board). All 5 electronic products were represented among them. Toxicity identification evaluations (with C18 and CM resins filtrations and ethylenediaminetetraacetic acid addition) indicated that metals caused the toxicity in the majority of the most toxic leachates. Overall, this study has shown that electronic waste can leach toxic compounds also during short-term leaching with pure water.

Quantifying uncertainty in stable isotope mixing models

DOE PAGES

Davis, Paul; Syme, James; Heikoop, Jeffrey; ...

2015-05-19

Mixing models are powerful tools for identifying biogeochemical sources and determining mixing fractions in a sample. However, identification of actual source contributors is often not simple, and source compositions typically vary or even overlap, significantly increasing model uncertainty in calculated mixing fractions. This study compares three probabilistic methods, SIAR [ Parnell et al., 2010] a pure Monte Carlo technique (PMC), and Stable Isotope Reference Source (SIRS) mixing model, a new technique that estimates mixing in systems with more than three sources and/or uncertain source compositions. In this paper, we use nitrate stable isotope examples (δ 15N and δ 18O) butmore » all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated mixing fractions.« less

Structural and spectroscopic characterization of irreversible phase changes in rapidly heated precursors of europium-doped titania nanoparticles

NASA Astrophysics Data System (ADS)

Gunawidjaja, Ray; Anderson, Benjamin R.; Eilers, Hergen

2018-02-01

We observe temperature-dependent phase changes in a precursor of europium-doped titania (p-Eu:TiO2) that is prepared via precipitation and is laser-heated to temperatures between 473 K and 1246 K within sub-second heating durations. The phase changes are characterized using X-ray diffraction and site-selective photoluminescence spectroscopy. We find that upon heating, the initially amorphous p-Eu:TiO2 first transforms into the anatase phase and then into a mixed anatase/rutile phase. These phase transformations change the local environment of the dopant Eu3+ ions resulting in modifications to the Eu3+ ions spectroscopic properties, with the modifications occurring for calcination temperatures above approximately 573 K following sub-second durations. These results demonstrate the temperature sensing ability of p-Eu:TiO2 nanoparticles for use in sub-second heating events. Moreover, at 573 K this temperature is lower than other host materials that we have evaluated (i.e., La2O3, ZrO2 and Y2O3).

Integrated Data Collection Analysis (IDCA) Program - Mixing Procedures and Materials Compatibility

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

Olinger, Becky D.; Sandstrom, Mary M.; Warner, Kirstin F.

Three mixing procedures have been standardized for the IDCA proficiency test—solid-solid, solid-liquid, and liquid-liquid. Due to the variety of precursors used in formulating the materials for the test, these three mixing methods have been designed to address all combinations of materials. Hand mixing is recommended for quantities less than 10 grams and Jar Mill mixing is recommended for quantities over 10 grams. Consideration must also be given to the type of container used for the mixing due to the wide range of chemical reactivity of the precursors and mixtures. Eight web site sources from container and chemical manufacturers have beenmore » consulted. Compatible materials have been compiled as a resource for selecting containers made of materials stable to the mixtures. In addition, container materials used in practice by the participating laboratories are discussed. Consulting chemical compatibility tables is highly recommended for each operation by each individual engaged in testing the materials in this proficiency test.« less

Vortex relaxation in type-II superconductors following current quenches

NASA Astrophysics Data System (ADS)

Chaturvedi, Harsh; Assi, Hiba; Dobramysl, Ulrich; Pleimling, Michel; Täuber, Uwe

2015-03-01

The mixed phase in type-II superconductors is characterized by the presence of mutually repulsive magnetic flux lines that are driven by external currents and pinned by point-like or extended material defects. We represent the disordered vortex system in the London limit by an elastic directed line model, whose relaxational dynamics we investigate numerically by means of Langevin Molecular Dynamics. We specifically study the effects of sudden changes of the driving current on the time evolution of the mean flux line gyration radius and the associated transverse displacement correlation functions. Upon quenching from the moving into the pinned glassy phase, we observe algebraically slow relaxation. The associated two-time height-autocorrelations display broken time translation invariance and can be described by a simple aging scaling form, albeit with non-universal scaling exponents. Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-09ER46613.

Material design of two-phase-coexisting niobate dielectrics by electrostatic adsorption

NASA Astrophysics Data System (ADS)

Fuchigami, Teruaki; Yoshida, Katsuya; Kakimoto, Ken-ichi

2017-10-01

A material design process using electrostatic adsorption was proposed to synthesize composite ceramics with a two-phase-coexisting structure. Supported particles were fabricated by the electrostatic adsorption of (Na,K)NbO3-SrTiO3 (NKN-ST) nanoparticles on (Na,K)NbO3-Ba2NaNb5O15 (NKN-BNN) particles. NKN-ST and NKN-BNN were well dispersed with no aggregate in NKN-ST/NKN-BNN ceramics synthesized using the supported particles in comparison with ceramics synthesized using a mixture obtained by simply mixing NKN-ST and NKN-BNN powder. The temperature dependence of dielectric constant is closely related to the composite structure and the dielectric constant was stable in a wide temperature range from room temperature to 400 °C. Capacitance for DC bias was also insensitive to temperature in the range of 0-2 kV/mm, and the change rate of the capacitance was within ±5% in the temperature range from room temperature to 200 °C.

A trans-phase granular continuum relation and its use in simulation

NASA Astrophysics Data System (ADS)

Kamrin, Ken; Dunatunga, Sachith; Askari, Hesam

The ability to model a large granular system as a continuum would offer tremendous benefits in computation time compared to discrete particle methods. However, two infamous problems arise in the pursuit of this vision: (i) the constitutive relation for granular materials is still unclear and hotly debated, and (ii) a model and corresponding numerical method must wear ``many hats'' as, in general circumstances, it must be able to capture and accurately represent the material as it crosses through its collisional, dense-flowing, and solid-like states. Here we present a minimal trans-phase model, merging an elastic response beneath a fictional yield criterion, a mu(I) rheology for liquid-like flow above the static yield criterion, and a disconnection rule to model separation of the grains into a low-temperature gas. We simulate our model with a meshless method (in high strain/mixing cases) and the finite-element method. It is able to match experimental data in many geometries, including collapsing columns, impact on granular beds, draining silos, and granular drag problems.

Thermal Conductivity of Eutectic Nitrates and Nitrates/Expanded Graphite Composite as Phase Change Materials.

PubMed

Xiao, Xin; Zhang, Peng; Meng, Zhao-Nan; Li, Ming

2015-04-01

Nitrates and eutectic nitrate mixtures are considered as potential phase change materials (PCMs) for the middle-temperature-range solar energy storage applications. But the extensive utilization is restricted by the poor thermal conductivity and thermal stability. In the present study, sodium nitrate-potassium nitrate eutectic mixture was used as the base PCM, and expanded graphite (EG) was added to the mixture so as to improve the thermal conductivities. The elaboration method consists of a physically mixing of salt powders with or without EG, and the composite PCMs were cold-compressed to form shape-stabilized PCMs at room temperature. The thermal conductivities of the composite PCMs fabricated by cold-compression were investigated at different temperatures by the steady state method. The results showed that the addition of EG significantly enhanced the thermal conductivities. The thermal conductivities of pure nitrates and nitrates/EG composite PCMs in solid state showed the behavior of temperature dependant, and they slightly decreased with the increase of the temperature.

Is the surface oxygen exchange rate linked to bulk ion diffusivity in mixed conducting Ruddlesden–Popper phases?

DOE PAGES

Tomkiewicz, Alex C.; Tamimi, Mazin A.; Huq, Ashfia; ...

2015-03-02

There is a possible link between oxygen surface exchange rate and bulk oxygen anion diffusivity in mixed ionic and electronic conducting oxides; it is a topic of great interest and debate. While a large body of experimental evidence and theoretical analyses support a link, observed differences between bulk and surface composition of these materials are hard to reconcile with this observation. This is further compounded by potential problems with simultaneous measurement of both parameters. Here we utilize separate techniques, in situ neutron diffraction and pulsed isotopic surface exchange, to examine bulk ion mobility and surface oxygen exchange rates of threemore » Ruddlesden-Popper phases, general form A n-1A 2'BnO 3n+1, A n-1A 2'BnX 3n+1; LaSrCo 0.5Fe 0.5O 4-δ (n = 1), La 0.3Sr 2.7CoFeO 7-δ (n = 2) and LaSr 3Co 1.5Fe 1.5O 10-δ (n = 3). These measurements are complemented by surface composition determination via high sensitivity-low energy ion scattering. We observe a correlation between bulk ion mobility and surface exchange rate between materials. The surface exchange rates vary by more than one order of magnitude with high anion mobility in the bulk of an oxygen vacancy-rich n = 2 Ruddlesden-Popper material correlating with rapid oxygen exchange. Furthermore this is in contrast with the similar surface exchange rates which we may expect due to similar surface compositions across all three samples. This paper conclude that experimental limitations lead to inherent convolution of surface and bulk rates, and that surface exchange steps are not likely to be rate limiting in oxygen incorporation.« less

Investigating mixed phase clouds using a synergy of ground based remote sensing measurements

NASA Astrophysics Data System (ADS)

Gierens, Rosa; Kneifel, Stefan; Löhnert, Ulrich

2017-04-01

Low level mixed phase clouds occur frequently in the Arctic, and can persist from hours to several days. However, the processes that lead to the commonality and persistence of these clouds are not well understood. The aim of our work is to get a more detailed understanding of the dynamics of and the processes in Arctic mixed phase clouds using a combination of instruments operating at the AWIPEV station in Svalbard. In addition, an aircraft campaign collecting in situ measurements inside mixed phase clouds above the station is planned for May-June 2017. The in situ data will be used for developing and validating retrievals for microphysical properties from Doppler cloud radar measurements. Once observational data for cloud properties is obtained, it can be used for evaluating model performance, for studies combining modeling and observational approaches, and eventually lead to developing model parameterizations of mixed phase microphysics. To describe the low-level mixed phase clouds, and the atmospheric conditions in which they occur, we present a case study of a persistent mixed phase cloud observed above the AWIPEV station. In the frame of the Arctic Amplification: Climate Relevant Atmospheric and Surface Processes and Feedback Mechanisms ((AC)3) -project, a millimeter wavelength cloud radar was installed at the site in June 2016. The high vertical (4 m in the lowest layer) and temporal (2.5 sec) resolution allows for a detailed description of the structure of the cloud. In addition to radar reflectivity and mean vertical velocity, we also utilize the higher moments of the Doppler spectra, such as skewness and kurtosis. To supplement the radar measurements, a ceilometer is used to detect liquid layers inside the cloud. Liquid water path and integrated water vapor are estimated using a microwave radiometer, which together with soundings can also provide temperature and humidity profiles in the lower troposphere. Moreover, a three-dimensional wind field is be obtained from a Doppler wind lidar. Furthermore, the Cloudnet scheme (www.cloud-net.org), that combines radar, lidar and microwave radiometer observations with a forecast model to provide a best estimate of cloud properties, is used for identifying mixed phase clouds. The continuous measurements carried out at AWIPEV make it possible to characterize the macro- and micro- physical properties of mixed-phase clouds on a long-term, statistical basis. The Arctic observations are compared to a 5-year observational data set from Jülich Observatory for Cloud Evolution (JOYCE) in Western Germany. The occurrence of different types of clouds (with focus on mixed-phase and super-cooled clouds), the distribution of ice and liquid within the clouds, the turbulent environment as well as the temperatures where the different phases are occurring are investigated.

Structure Elucidation of Mixed-Linker Zeolitic Imidazolate Frameworks by Solid-State (1)H CRAMPS NMR Spectroscopy and Computational Modeling.

PubMed

Jayachandrababu, Krishna C; Verploegh, Ross J; Leisen, Johannes; Nieuwendaal, Ryan C; Sholl, David S; Nair, Sankar

2016-06-15

Mixed-linker zeolitic imidazolate frameworks (ZIFs) are nanoporous materials that exhibit continuous and controllable tunability of properties like effective pore size, hydrophobicity, and organophilicity. The structure of mixed-linker ZIFs has been studied on macroscopic scales using gravimetric and spectroscopic techniques. However, it has so far not been possible to obtain information on unit-cell-level linker distribution, an understanding of which is key to predicting and controlling their adsorption and diffusion properties. We demonstrate the use of (1)H combined rotation and multiple pulse spectroscopy (CRAMPS) NMR spin exchange measurements in combination with computational modeling to elucidate potential structures of mixed-linker ZIFs, particularly the ZIF 8-90 series. All of the compositions studied have structures that have linkers mixed at a unit-cell-level as opposed to separated or highly clustered phases within the same crystal. Direct experimental observations of linker mixing were accomplished by measuring the proton spin exchange behavior between functional groups on the linkers. The data were then fitted to a kinetic spin exchange model using proton positions from candidate mixed-linker ZIF structures that were generated computationally using the short-range order (SRO) parameter as a measure of the ordering, clustering, or randomization of the linkers. The present method offers the advantages of sensitivity without requiring isotope enrichment, a straightforward NMR pulse sequence, and an analysis framework that allows one to relate spin diffusion behavior to proposed atomic positions. We find that structures close to equimolar composition of the two linkers show a greater tendency for linker clustering than what would be predicted based on random models. Using computational modeling we have also shown how the window-type distribution in experimentally synthesized mixed-linker ZIF-8-90 materials varies as a function of their composition. The structural information thus obtained can be further used for predicting, screening, or understanding the tunable adsorption and diffusion behavior of mixed-linker ZIFs, for which the knowledge of linker distributions in the framework is expected to be important.

Relating rheology to geometry in large-scale natural shear zones

NASA Astrophysics Data System (ADS)

Platt, John

2016-04-01

The geometry and width of the ductile roots of plate boundary scale faults are very poorly understood. Some field and geophysical data suggests widths of tens of km in the lower crust, possibly more in the upper mantle. Other observations suggest they are much narrower. Dip slip shear zones may flatten out and merge into zones of subhorizontal lower crustal or asthenospheric flow. The width of a ductile shear zone is simply related to relative velocity and strain rate. Strain rate is related to stress through the constitutive relationship. Can we constrain the stress, and do we understand the rheology of materials in ductile shear zones? A lot depends on how shear zones are initiated. If they are localized by pre-existing structures, width and/or rheology may be inherited, and we have too many variables. If shear zones are localized primarily by shear heating, initial shear stress has to be very high (> 1 GPa) to overcome conductive heat loss, and very large feedbacks (both positive and negative) make the system highly unstable. Microstructural weakening requires a minimum level of stress to cause deformation and damage in surrounding rock, thereby buffering the stress. Microstructural weakening leads to grain-size sensitive creep, for which we have constitutive laws, but these are complicated by phase mixing in polyphase materials, by viscous anisotropy, by hydration, and by changes in mineral assemblage. Here are some questions that need to be addressed. (1) If grain-size reduction by dynamic recrystallization results in a switch to grain-size sensitive creep (GSSC) in a stress-buffered shear zone, does dynamic recrystallization stop? Does grain growth set in? If grain-size is still controlled by dislocation processes, then the effective stress exponent for GSSC is 4-5, even though the dominant mechanism may be diffusion and/or grain-boundary sliding (GBS). (2) Is phase mixing in ultramylonites primarily a result of GBS + neighbour switching, creep cavitation and diffusion, or metamorphic reactions? (3) In two-phase / polyphase mixtures, does the strong phase generally form a load-bearing framework, favoring constant strain-rate (Voigt) bound behavior, or does the weak phase form through-going strain pathways, favoring constant stress (Reuss) bound behavior, or do the phases remain well mixed, favoring an intermediate behavior (e.g., Tullis et al model)? (4) How do we deal with the rheological effect of water? Is it simply an unconstrained variable in nature? Is the water fugacity model in flow laws adequate? (5) How can we better relate experimental results (often carried out at constant strain-rate, and not reaching microstructural steady state) to deformation in natural shear zones? Rheological observations on well-constrained natural shear zones are helping us answer some of these questions.

Tower reactors for bioconversion of lignocellulosic material

DOEpatents

Nguyen, Quang A.

1999-01-01

An apparatus for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards or downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets.

Tower reactors for bioconversion of lignocellulosic material

DOEpatents

Nguyen, Quang A.

1998-01-01

An apparatus for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards of downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets.

High-power beam steering using phase conjugation through Brillouin-induced four-wave mixing.

PubMed

Jones, D C; Cook, G; Ridley, K D; Scott, A M

1991-10-15

We report an experimental demonstration of a beam-steering concept. A high-reflectivity phase-conjugate mirror is used to steer a high-power phase-conjugate beam using a low-power signal beam. The high reflectivity phase conjugation is achieved using Brillouin-induced four-wave mixing in a cell containing carbon disulfide.

A New Class of Ternary Compound for Lithium-Ion Battery: from Composite to Solid Solution.

PubMed

Wang, Jiali; Wu, Hailong; Cui, Yanhua; Liu, Shengzhou; Tian, Xiaoqing; Cui, Yixiu; Liu, Xiaojiang; Yang, Yin

2018-02-14

Searching for high-performance cathode materials is a crucial task to develop advanced lithium-ion batteries (LIBs) with high-energy densities for electrical vehicles (EVs). As a promising lithium-rich material, Li 2 MnO 3 delivers high capacity over 200 mAh g -1 but suffers from poor structural stability and electronic conductivity. Replacing Mn 4+ ions by relatively larger Sn 4+ ions is regarded as a possible strategy to improve structural stability and thus cycling performance of Li 2 MnO 3 material. However, large difference in ionic radii of Mn 4+ and Sn 4+ ions leads to phase separation of Li 2 MnO 3 and Li 2 SnO 3 during high-temperature synthesis. To prepare solid-solution phase of Li 2 MnO 3 -Li 2 SnO 3 , a buffer agent of Ru 4+ , whose ionic radius is in between that of Mn 4+ and Sn 4+ ions, is introduced to assist the formation of a single solid-solution phase. The results show that the Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system evolves from mixed composite phases into a single solid-solution phase with increasing Ru content. Meanwhile, discharge capacity of this ternary system shows significantly increase at the transformation point which is ascribed to the improvement of Li + /e - transportation kinetics and anionic redox chemistry for solid-solution phase. The role of Mn/Sn molar ratio of Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system has also been studied. It is revealed that higher Sn content benefits cycling stability of the system because Sn 4+ ions with larger sizes could partially block the migration of Mn 4+ and Ru 4+ from transition metal layer to Li layer, thus suppressing structural transformation of the system from layered-to-spinel phase. These findings may enable a new route for exploring ternary or even quaternary lithium-rich cathode materials for LIBs.

Ordered mixed-layer structures in the Mighei carbonaceous chondrite matrix

NASA Technical Reports Server (NTRS)

Mackinnon, I. D. R.

1982-01-01

High resolution transmission electron microscopy of the Mighei carbonaceous chondrite matrix has revealed the presence of a new mixed layer structure material. This mixed-layer material consists of an ordered arrangement of serpentine-type (S) and brucite-type (B) layers in the sequence SBBSBB. Electron diffraction and imaging techniques show that the basal periodicity is approximately 17 A. Discrete crystals of SBB-type material are typically curved, of small size (less than 1 micron) and show structural variations similar to the serpentine group minerals. Mixed-layer material also occurs in association with planar serpentine. Characteristics of SBB-type material are not consistent with known terrestrial mixed-layer clay minerals. Evidence for formation by a condensation event or by subsequent alteration of pre-existing material is not yet apparent.

Processes that generate and deplete liquid water and snow in thin midlevel mixed-phase clouds

NASA Astrophysics Data System (ADS)

Smith, Adam J.; Larson, Vincent E.; Niu, Jianguo; Kankiewicz, J. Adam; Carey, Lawrence D.

2009-06-01

This paper uses a numerical model to investigate microphysical, radiative, and dynamical processes in mixed-phase altostratocumulus clouds. Three cloud cases are chosen for study, each of which was observed by aircraft during the fifth or ninth Complex Layered Cloud Experiment (CLEX). These three clouds are numerically modeled using large-eddy simulation (LES). The observed and modeled clouds consist of a mixed-phase layer with a quasi-adiabatic profile of liquid, and a virga layer below that consists of snow. A budget of cloud (liquid) water mixing ratio is constructed from the simulations. It shows that large-scale ascent/descent, radiative cooling/heating, turbulent transport, and microphysical processes are all significant. Liquid is depleted indirectly via depositional growth of snow (the Bergeron-Findeisen process). This process is more influential than depletion of liquid via accretional growth of snow. Also constructed is a budget of snow mixing ratio, which turns out to be somewhat simpler. It shows that snow grows by deposition in and below the liquid (mixed-phase) layer, and sublimates in the remainder of the virga region below. The deposition and sublimation are balanced primarily by sedimentation, which transports the snow from the growth region to the sublimation region below. In our three clouds, the vertical extent of the virga layer is influenced more by the profile of saturation ratio below the liquid (mixed-phase) layer than by the mixing ratio of snow at the top of the virga layer.

Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites

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

Draguta, Sergiu; Sharia, Onise; Yoon, Seog Joon

Mixed halide hybrid perovskites, CH 3NH 3Pb(I 1-xBrx) 3' represent good candidates for lowcost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material’s optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodiderich phases. It additionallymore » explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.« less

Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites

DOE PAGES

Draguta, Sergiu; Sharia, Onise; Yoon, Seog Joon; ...

2017-08-04

Mixed halide hybrid perovskites, CH 3NH 3Pb(I 1-xBrx) 3' represent good candidates for lowcost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material’s optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodiderich phases. It additionallymore » explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.« less

Anisotropic Magnetohydrodynamic Turbulence Driven by Parametric Decay Instability: The Onset of Phase Mixing and Alfvén Wave Turbulence

NASA Astrophysics Data System (ADS)

Shoda, Munehito; Yokoyama, Takaaki

2018-06-01

We conduct a 3D magnetohydrodynamic (MHD) simulation of the parametric decay instability of Alfvén waves and resultant compressible MHD turbulence, which is likely to develop in the solar wind acceleration region. Because of the presence of the mean magnetic field, the nonlinear stage is characterized by filament-like structuring and anisotropic cascading. By calculating the timescales of phase mixing and the evolution of Alfvén wave turbulence, we have found that the early nonlinear stage is dominated by phase mixing, while the later phase is dominated by imbalanced Alfvén wave turbulence. Our results indicate that the regions in the solar atmosphere with large density fluctuation, such as the coronal bottom and wind acceleration region, are heated by phase-mixed Alfvén waves, while the other regions are heated by Alfvén wave turbulence.

Greenhouse gas emissions of alternative pavement designs: framework development and illustrative application.

PubMed

Liu, Xiaoyu; Cui, Qingbin; Schwartz, Charles

2014-01-01

Pavement rehabilitation is carbon intensive and the choice of pavement type is a critical factor in controlling greenhouse gas (GHG) emissions. The existing body of knowledge is not able to support decision-making on pavement choice due to a lack of consensus on the system boundaries, the functional units and the estimation periods. Excessive data requirements further inhibit the generalization of the existing methodologies for design evaluation at the early planning stage. This study proposes a practical life-cycle GHG estimation approach, which is arguably effective to benchmark pavement emissions given project bid tabulation. A set of case studies conducted for this study suggest that recycled asphalt pavement (e.g., foam stabilized base (FSB), and warm mix asphalt (WMA)) would prevent up to 50% of GHGs from the initial construction phase. However, from a life-cycle perspective, pavement emissions are dictated largely by the traffic characteristics and the analysis period for the use phase. The benefits from using recycled materials (e.g., FSB) are likely to diminish if the recycled products do not perform as well as those properly proportioned with less recycled materials, or if the recycled materials are locally unavailable. When the AADT reaches 10,000, use phase releases more than 97% of the life cycle emissions and the emissions difference among alternative designs will be within 1%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Phase Behaviour and Miscibility Studies of Collagen/Silk Fibroin Macromolecular System in Dilute Solutions and Solid State.

PubMed

Ghaeli, Ima; de Moraes, Mariana A; Beppu, Marisa M; Lewandowska, Katarzyna; Sionkowska, Alina; Ferreira-da-Silva, Frederico; Ferraz, Maria P; Monteiro, Fernando J

2017-08-18

Miscibility is an important issue in biopolymer blends for analysis of the behavior of polymer pairs through the detection of phase separation and improvement of the mechanical and physical properties of the blend. This study presents the formulation of a stable and one-phase mixture of collagen and regenerated silk fibroin (RSF), with the highest miscibility ratio between these two macromolecules, through inducing electrostatic interactions, using salt ions. For this aim, a ternary phase diagram was experimentally built for the mixtures, based on observations of phase behavior of blend solutions with various ratios. The miscibility behavior of the blend solutions in the miscible zones of the phase diagram was confirmed quantitatively by viscosimetric measurements. Assessing the effects of biopolymer mixing ratio and salt ions, before and after dialysis of blend solutions, revealed the importance of ion-specific interactions in the formation of coacervate-based materials containing collagen and RSF blends that can be used in pharmaceutical, drug delivery, and biomedical applications. Moreover, the conformational change of silk fibroin from random coil to beta sheet, in solution and in the final solid films, was detected by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. Scanning electron microscopy (SEM) exhibited alterations of surface morphology for the biocomposite films with different ratios. Surface contact angle measurement illustrated different hydrophobic properties for the blended film surfaces. Differential scanning calorimetry (DSC) showed that the formation of the beta sheet structure of silk fibroin enhances the thermal stability of the final blend films. Therefore, the novel method presented in this study resulted in the formation of biocomposite films whose physico-chemical properties can be tuned by silk fibroin conformational changes by applying different component mixing ratios.

Novel synthesis of manganese and vanadium mixed oxide (V{sub 2}O{sub 5}/OMS-2) as an efficient and selective catalyst for the oxidation of alcohols in liquid phase

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

Mahdavi, Vahid, E-mail: v-mahdavi@araku.ac.ir; Soleimani, Shima

2014-03-01

Graphical abstract: Oxidation of various alcohols is studied in the liquid phase over new composite mixed oxide (V{sub 2}O{sub 5}/OMS-2) catalyst using tert-butyl hydroperoxide (TBHP). The activity of V{sub 2}O{sub 5}/OMS-2 samples was considerably increased with respect to OMS-2 catalyst and these samples are found to be suitable for the selective oxidation of alcohols. - Highlights: • V{sub 2}O{sub 5}/K-OMS-2 with different V/Mn molar ratios prepared by the impregnation method. • Oxidation of alcohols was studied in the liquid phase over V{sub 2}O{sub 5}/K-OMS-2 catalyst. • V{sub 2}O{sub 5}/K-OMS-2 catalyst had excellent activity for alcohol oxidation. • Benzyl alcohol oxidationmore » using excess TBHP followed a pseudo-first order kinetic. • The selected catalyst was reused without significant loss of activity. - Abstract: This work reports the synthesis and characterization of mixed oxide vanadium–manganese V{sub 2}O{sub 5}/K-OMS-2 at various V/Mn molar ratios and prepared by the impregnation method. Characterization of these new composite materials was made by elemental analysis, BET, XRD, FT-IR, SEM and TEM techniques. Results of these analyses showed that vanadium impregnated samples contained mixed phases of cryptomelane and crystalline V{sub 2}O{sub 5} species. Oxidation of various alcohols was studied in the liquid phase over the V{sub 2}O{sub 5}/K-OMS-2 catalyst using tert-butyl hydroperoxide (TBHP) and H{sub 2}O{sub 2} as the oxidant. Activity of the V{sub 2}O{sub 5}/K-OMS-2 samples was increased considerably with respect to K-OMS-2 catalyst due to the interaction of manganese oxide and V{sub 2}O{sub 5}. The kinetic of benzyl alcohol oxidation using excess TBHP over V{sub 2}O{sub 5}/K-OMS-2 catalyst was investigated at different temperatures and a pseudo-first order reaction was determined with respect to benzyl alcohol. The effects of reaction time, oxidant/alcohol molar ratio, reaction temperature, solvents, catalyst recycling potential and leaching were investigated.« less

The influence of pozzolanic materials on the mechanical stability of aluminous cement

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

Collepardi, M.; Monosi, S.; Piccioli, P.

1995-07-01

High alumina cement is particularly suitable for manufacturing sulphate resistant concretes and in particular cement mixes which are able resist the sear water aggression. High alumina cement paste, in the presence of silica fume, shows an increasing strength trend even at 20 C and 40 C, since this pozzolan causes the formation of gehlenite hydrate (C{sub 2}ASH{sub 8}) and therefore strongly reduces the transformation of hexagonal aluminate hydrates (CAH{sub 10}, C{sub 2}AH{sub 8}) into the cubic hydrate (C{sub 3}AH{sub 6}) which is responsible for the strength loss of high-alumina cement mixes at higher temperatures (>20 C). On the contrary, flymore » ash is not suitable for reducing the transformation of hexagonal hydrates into the cubic phase. Consequently, the strength at 20 C and 40 C of the fly ash-high alumina cement mixes decrease as well as the high alumina cement pastes in the absence of pozzolan.« less

Carbon Nanotube Chopped Fiber for Enhanced Properties in Additive Manufacturing

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

Menchhofer, Paul A.; Johnson, Joseph E.; Lindahl, John M.

2016-06-06

Nanocomp Technologies, Inc. is working with Oak Ridge National Laboratory to develop carbon nanotube (CNT) composite materials and evaluate their use in additive manufacturing (3D printing). The first phase demonstrated feasibility and improvements for carbon nanotube (CNT)- acrylonitrile butadiene styrene (ABS) composite filaments use in additive manufacturing, with potential future work centering on further improvements. By focusing the initial phase on standard processing methods (developed mainly for the incorporation of carbon fibers in ABS) and characterization techniques, a basis of knowledge for the incorporation of CNTs in ABS was learned. The ability to understand the various processing variables is criticalmore » to the successful development of these composites. From the degradation effects on ABS (caused by excessive temperatures), to the length of time the ABS is in the melt state, to the order of addition of constituents, and also to the many possible mixing approaches, a workable flow sequence that addresses each processing step is critical to the final material properties. Although this initial phase could not deal with each of these variables in-depth, a future study is recommended that will build on the lessons learned for this effort.« less

Tailoring the optical characteristics of microsized InP nanoneedles directly grown on silicon.

PubMed

Li, Kun; Sun, Hao; Ren, Fan; Ng, Kar Wei; Tran, Thai-Truong D; Chen, Roger; Chang-Hasnain, Connie J

2014-01-08

Nanoscale self-assembly offers a pathway to realize heterogeneous integration of III-V materials on silicon. However, for III-V nanowires directly grown on silicon, dislocation-free single-crystal quality could only be attained below certain critical dimensions. We recently reported a new approach that overcomes this size constraint, demonstrating the growth of single-crystal InGaAs/GaAs and InP nanoneedles with the base diameters exceeding 1 μm. Here, we report distinct optical characteristics of InP nanoneedles which are varied from mostly zincblende, zincblende/wurtzite-mixed, to pure wurtzite crystalline phase. We achieved, for the first time, pure single-crystal wurtzite-phase InP nanoneedles grown on silicon with bandgaps of 80 meV larger than that of zincblende-phase InP. Being able to attain excellent material quality while scaling up in size promises outstanding device performance of these nanoneedles. At room temperature, a high internal quantum efficiency of 25% and optically pumped lasing are demonstrated for single nanoneedle as-grown on silicon substrate. Recombination dynamics proves the excellent surface quality of the InP nanoneedles, which paves the way toward achieving multijunction photovoltaic cells, long-wavelength heterostructure lasers, and advanced photonic integrated circuits.

Application of the base catalyzed decomposition process to treatment of PCB-contaminated insulation and other materials associated with US Navy vessels. Final report

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

Schmidt, A.J.; Zacher, A.H.; Gano, S.R.

1996-09-01

The BCD process was applied to dechlorination of two types of PCB-contaminated materials generated from Navy vessel decommissioning activities at Puget Sound Naval Shipyard: insulation of wool felt impregnated with PCB, and PCB-containing paint chips/debris from removal of paint from metal surfaces. The BCD process is a two-stage, low-temperature chemical dehalogenation process. In Stage 1, the materials are mixed with sodium bicarbonate and heated to 350 C. The volatilized halogenated contaminants (eg, PCBs, dioxins, furans), which are collected in a small volume of particulates and granular activated carbon, are decomposed by the liquid-phase reaction (Stage 2) in a stirred-tank reactor,more » using a high-boiling-point hydrocarbon oil as the reaction medium, with addition of a hydrogen donor, a base (NaOH), and a catalyst. The tests showed that treating wool felt insulation and paint chip wastes with Stage 2 on a large scale is feasible, but compared with current disposal costs for PCB-contaminated materials, using Stage 2 would not be economical at this time. For paint chips generated from shot/sand blasting, the solid-phase BCD process (Stage 1) should be considered, if paint removal activities are accelerated in the future.« less

Helically agitated mixing in dry dilute acid pretreatment enhances the bioconversion of corn stover into ethanol

PubMed Central

2014-01-01

Background Dry dilute acid pretreatment at extremely high solids loading of lignocellulose materials demonstrated promising advantages of no waste water generation, less sugar loss, and low steam consumption while maintaining high hydrolysis yield. However, the routine pretreatment reactor without mixing apparatus was found not suitable for dry pretreatment operation because of poor mixing and mass transfer. In this study, helically agitated mixing was introduced into the dry dilute acid pretreatment of corn stover and its effect on pretreatment efficiency, inhibitor generation, sugar production, and bioconversion efficiency through simultaneous saccharification and ethanol fermentation (SSF) were evaluated. Results The overall cellulose conversion taking account of cellulose loss in pretreatment was used to evaluate the efficiency of pretreatment. The two-phase computational fluid dynamics (CFD) model on dry pretreatment was established and applied to analyze the mixing mechanism. The results showed that the pretreatment efficiency was significantly improved and the inhibitor generation was reduced by the helically agitated mixing, compared to the dry pretreatment without mixing: the ethanol titer and yield from cellulose in the SSF reached 56.20 g/L and 69.43% at the 30% solids loading and 15 FPU/DM cellulase dosage, respectively, corresponding to a 26.5% increase in ethanol titer and 17.2% increase in ethanol yield at the same fermentation conditions. Conclusions The advantage of helically agitated mixing may provide a prototype of dry dilute acid pretreatment processing for future commercial-scale production of cellulosic ethanol. PMID:24387051

Corrosion of low alloy steel containing 0.5% chromium in supercritical CO2-saturated brine and water-saturated supercritical CO2 environments

NASA Astrophysics Data System (ADS)

Wei, Liang; Gao, Kewei; Li, Qian

2018-05-01

The corrosion behavior of P110 low-Cr alloy steel in supercritical CO2-saturated brine (aqueous phase) and water-saturated supercritical CO2 (SC CO2 phase) was investigated. The results show that P110 steel primarily suffered general corrosion in the aqueous phase, while severe localized corrosion occurred in the SC CO2 phase. The formation of corrosion product scale on P110 steel in the aqueous phase divided into three stages: formation of the initial corrosion layer containing amorphous Cr(OH)3, FeCO3 and a small amount of Fe3C; transformation of initial corrosion layer to mixed layer, which consisted of FeCO3 and a small amount of Cr(OH)3 and Fe3C; growth and dissolution of the mixed layer. Finally, only a single mixed layer covered on the steel in the aqueous phase. However, the scale formed in SC CO2 phase consisted of two layers: the inner mixed layer and the dense outer FeCO3 crystalline layer.

A Melting Layer Model for Passive/Active Microwave Remote Sensing Applications. Part 1; Model Formulation and Comparison with Observations

NASA Technical Reports Server (NTRS)

Olson, William S.; Bauer, Peter; Viltard, Nicolas F.; Johnson, Daniel E.; Tao, Wei-Kuo

2000-01-01

In this study, a 1-D steady-state microphysical model which describes the vertical distribution of melting precipitation particles is developed. The model is driven by the ice-phase precipitation distributions just above the freezing level at applicable gridpoints of "parent" 3-D cloud-resolving model (CRM) simulations. It extends these simulations by providing the number density and meltwater fraction of each particle in finely separated size categories through the melting layer. The depth of the modeled melting layer is primarily determined by the initial material density of the ice-phase precipitation. The radiative properties of melting precipitation at microwave frequencies are calculated based upon different methods for describing the dielectric properties of mixed phase particles. Particle absorption and scattering efficiencies at the Tropical Rainfall Measuring Mission Microwave Imager frequencies (10.65 to 85.5 GHz) are enhanced greatly for relatively small (approx. 0.1) meltwater fractions. The relatively large number of partially-melted particles just below the freezing level in stratiform regions leads to significant microwave absorption, well-exceeding the absorption by rain at the base of the melting layer. Calculated precipitation backscatter efficiencies at the Precipitation Radar frequency (13.8 GHz) increase in proportion to the particle meltwater fraction, leading to a "bright-band" of enhanced radar reflectivities in agreement with previous studies. The radiative properties of the melting layer are determined by the choice of dielectric models and the initial water contents and material densities of the "seeding" ice-phase precipitation particles. Simulated melting layer profiles based upon snow described by the Fabry-Szyrmer core-shell dielectric model and graupel described by the Maxwell-Garnett water matrix dielectric model lead to reasonable agreement with radar-derived melting layer optical depth distributions. Moreover, control profiles that do not contain mixed-phase precipitation particles yield optical depths that are systematically lower than those observed. Therefore, the use of the melting layer model to extend 3-D CRM simulations appears justified, at least until more realistic spectral methods for describing melting precipitation in high-resolution, 3-D CRM's are implemented.

Model of the Phase Transition Mimicking the Pasta Phase in Cold and Dense Quark-Hadron Matter

NASA Astrophysics Data System (ADS)

Ayriyan, Alexander; Grigorian, Hovik

2018-02-01

A simple mixed phase model mimicking so-called "pasta" phases in the quarkhadron phase transition is developed and applied to static neutron stars for the case of DD2 type hadronic and NJL type quark matter models. The influence of the mixed phase on the mass-radius relation of the compact stars is investigated. Model parameters are chosen such that the results are in agreement with the mass-radius constraints.

Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds.

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

Rambukkange,M.; Verlinde, J.; Elorante, E.

2006-07-10

Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004) showed that Doppler spectra has potential to separate the contributions to the total reflectivitymore » of the liquid and solid water in the radar volume, and thus to investigate further Hallett and Viddaurre's findings. The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted along the NSA to investigate the properties of Arctic mixed phase clouds (Verlinde et al., 2006). We present surface based remote sensing data from MPACE to discuss the fine-scale structure of the mixed-phase clouds observed during this experiment.« less

Applications of x ray absorption fine structure to the in situ study of the effect of cobalt in nickel hydrous oxide electrodes for fuel cells and rechargeable batteries

NASA Technical Reports Server (NTRS)

Kim, Sunghyun; Tryk, Donald A.; Scherson, Daniel A.; Antonio, Mark R.

1993-01-01

Electronic and structural aspects of composite nickel-cobalt hydrous oxides have been examined in alkaline solutions using in situ X-ray absorption fine structure (XAFS). The results obtained have indicated that cobalt in this material is present as cobaltic ions regardless of the oxidation state of nickel in the lattice. Furthermore, careful analysis of the Co K-edge Extended X-ray absorption fine structure data reveals that the co-electrodeposition procedure generates a single phase, mixed metal hydrous oxide, in which cobaltic ions occupy nickel sites in the NiO2 sheet-like layers and not two intermixed phases each consisting of a single metal hydrous oxide.

Quantum propagation in single mode fiber

NASA Technical Reports Server (NTRS)

Joneckis, Lance G.; Shapiro, Jeffrey H.

1994-01-01

This paper presents a theory for quantum light propagation in a single-mode fiber which includes the effects of the Kerr nonlinearity, group-velocity dispersion, and linear loss. The theory reproduces the results of classical self-phase modulation, quantum four-wave mixing, and classical solution physics, within their respective regions of validity. It demonstrates the crucial role played by the Kerr-effect material time constant, in limiting the quantum phase shifts caused by the broadband zero-point fluctuations that accompany any quantized input field. Operator moment equations - approximated, numerically, via a terminated cumulant expansion - are used to obtain results for homodyne-measurement noise spectra when dispersion is negligible. More complicated forms of these equations can be used to incorporate dispersion into the noise calculations.

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

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

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a uniquemore » opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained beta-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.« less

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

NASA Astrophysics Data System (ADS)

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

2016-10-01

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained β-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.

A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M11–xM2xB2 alloys with AlB2 type structure

PubMed Central

Alling, B.; Högberg, H.; Armiento, R.; Rosen, J.; Hultman, L.

2015-01-01

Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M11–xM2xB2 alloys comprising MiB2 (Mi = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1–xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2. PMID:25970763

Ammonia Inactivation of Ascaris Ova in Ecological Compost by Using Urine and Ash

PubMed Central

Parzen, Rebecca E.; Mercado Guzmán, Álvaro

2012-01-01

Viable ova of Ascaris lumbricoides, an indicator organism for pathogens, are frequently found in feces-derived compost produced from ecological toilets, demonstrating that threshold levels of time, temperature, pH, and moisture content for pathogen inactivation are not routinely met. Previous studies have determined that NH3 has ovicidal properties for pathogens, including Ascaris ova. This research attempted to achieve Ascaris inactivation via NH3 under environmental conditions commonly found in ecological toilets and using materials universally available in an ecological sanitation setting, including compost (feces and sawdust), urine, and ash. Compost mixed with stored urine and ash produced the most rapid inactivation, with significant inactivation observed after 2 weeks and with a time to 99% ovum inactivation (T99) of 8 weeks. Compost mixed with fresh urine and ash achieved a T99 of 15 weeks, after a 4-week lag phase. Both matrices had relatively high total-ammonia concentrations and pH values of >9.24 (pKa of ammonia). In compost mixed with ash only, and in compost mixed with fresh urine only, inactivation was observed after an 11-week lag phase. These matrices contained NH3 concentrations of 164 to 173 and 102 to 277 mg/liter, respectively, when inactivation occurred, which was below the previously hypothesized threshold for inactivation (280 mg/liter), suggesting that a lower threshold NH3 concentration may be possible with a longer contact time. Other significant results include the hydrolysis of urea to ammonia between pH values of 10.4 and 11.6, above the literature threshold pH of 10. PMID:22582051

Ammonia inactivation of Ascaris ova in ecological compost by using urine and ash.

PubMed

McKinley, James W; Parzen, Rebecca E; Mercado Guzmán, Álvaro

2012-08-01

Viable ova of Ascaris lumbricoides, an indicator organism for pathogens, are frequently found in feces-derived compost produced from ecological toilets, demonstrating that threshold levels of time, temperature, pH, and moisture content for pathogen inactivation are not routinely met. Previous studies have determined that NH(3) has ovicidal properties for pathogens, including Ascaris ova. This research attempted to achieve Ascaris inactivation via NH(3) under environmental conditions commonly found in ecological toilets and using materials universally available in an ecological sanitation setting, including compost (feces and sawdust), urine, and ash. Compost mixed with stored urine and ash produced the most rapid inactivation, with significant inactivation observed after 2 weeks and with a time to 99% ovum inactivation (T(99)) of 8 weeks. Compost mixed with fresh urine and ash achieved a T(99) of 15 weeks, after a 4-week lag phase. Both matrices had relatively high total-ammonia concentrations and pH values of >9.24 (pK(a) of ammonia). In compost mixed with ash only, and in compost mixed with fresh urine only, inactivation was observed after an 11-week lag phase. These matrices contained NH(3) concentrations of 164 to 173 and 102 to 277 mg/liter, respectively, when inactivation occurred, which was below the previously hypothesized threshold for inactivation (280 mg/liter), suggesting that a lower threshold NH(3) concentration may be possible with a longer contact time. Other significant results include the hydrolysis of urea to ammonia between pH values of 10.4 and 11.6, above the literature threshold pH of 10.

Towards multimodal HPLC separations on humic acid-bonded aminopropyl silica: RPLC and HILIC behavior.

PubMed

Gezici, Orhan; Kara, Hüseyin

2011-09-15

The stationary phase characteristics of the material obtained through immobilization of humic acid (HA) to aminopropyl silica (APS) via amide-bond formation were investigated. The material was characterized in terms of elemental analysis, FTIR, thermogravimetric analyses, pH point of zero charge measurements, potentiometric titrations, and contact angle measurements. Amount of HA bonded to APS was determined from the elemental analysis results, and found as 170 mgHA/gAPS. Stability of the material was studied in aqueous media at different pH values, and amount of HA released at pH=8 did not exceed 2% of the total immobilized HA. Stationary phase characteristics of the well-characterized material were investigated in an HPLC system by using some low-molecular weight polar compounds (i.e. some nucleosides and nucleobases) as test solutes. Effect of some experimental variables such as column conditioning, composition of mobile phase, and temperature on the chromatographic behavior of the studied compounds was studied. Role of ammonium solutions at different pH values on retentive properties of the species was also studied. Retention factors (k') versus volume percentage of organic modifier exhibited a U-curve, which was evaluated as an indication for RPLC/HILIC mixed-mode behavior of the stationary phase. Orthogonality between RPLC and HILIC modes was analyzed through geometric approach, and found as 48.5%. Base-line separation for the studied groups of compounds was achieved under each studied mode, and some differentiations were observed in elution order of the compounds depending on the HPLC mode applied. Chromatograms recorded under RPLC and HILIC modes were compared with those recorded on APS under similar conditions, and thus the influence/importance of HA immobilization process was evaluated in detail. In light of the obtained results, immobilized HA is represented as a useful stationary phase for HPLC separations. Copyright © 2011 Elsevier B.V. All rights reserved.

40 CFR Appendix V to Part 264 - Examples of Potentially Incompatible Waste

Code of Federal Regulations, 2010 CFR

2010-07-01

... harmful consequences which result from mixing materials in one group with materials in another group. The...., a strong acid mixed with a strong base), or that controls substances produced (e.g., by generating... -incinerator). In the lists below, the mixing of a Group A material with a Group B material may have the...

Experiments on the rise and mixing in neutral crossflow of plumes from two identical sources for different wind directions

NASA Astrophysics Data System (ADS)

Contini, Daniele; Robins, Alan

A study of the mixing phase of two identical buoyant plumes emitted from adjacent sources into a neutral cross-flow is presented. Results were obtained in a water towing-tank by using both quantitative plume visualisations and point concentration detection with a colorimeter system. Plume trajectories and cross-sectional distributions of concentration were obtained for different flow directions, φ, with respect to the source axis and for two stack separations. Particular attention has been given to the influence of φ on plume trajectories during the mixing phase and to the changes in the shape of the plume cores, induced during the mixing, that influence the rate of entrainment of ambient fluid. The results show that the additional rise, E, of the combined plume decreases almost linearly with sin( φ) when φ is increased, and vanishes when φ is around 20-30°; thereafter, E becomes negative, due to the presence of a form of "induced downwash" effect. The rise reduction is a consequence of the complex and protracted mixing of two vortices of opposite vorticity that creates strong asymmetry in the concentration distribution within the plume core, resulting in an accumulation of plume material at the bottom of the combined plume and a consequent decrease of the height of the centre of mass of the combined plume. There is clear evidence that the asymmetry slowly diminishes during plume development, so that at large distance from the mixing zone the concentration distribution becomes similar to that of a single plume with a characteristic double-vortex structure, though this develops with a deficit in plume rise. Results also show that the average dilution over a cross-section of the plume increases with φ and, when φ reaches 90°, becomes approximately equal to that in a single plume, even though the actual tracer distribution is quite different, particularly at short distances from the sources.

In situ reinforced polymers using low molecular weight compounds

NASA Astrophysics Data System (ADS)

Yordem, Onur Sinan

2011-12-01

The primary objective of this research is to generate reinforcing domains in situ during the processing of polymers by using phase separation techniques. Low molecular weight compounds were mixed with polymers where the process viscosity is reduced at process temperatures and mechanical properties are improved once the material system is cooled or reacted. Thermally induced phase separation and thermotropic phase transformation of low molar mass compounds were used in isotactic polypropylene (iPP) and poly(ether ether ketone) (PEEK) resins. Reaction induced phase separation was utilized in thermosets to generate anisotropic reinforcements. A new strategy to increase fracture toughness of materials was introduced. Simultaneously, enhancement in stiffness and reduction in process viscosity were also attained. Materials with improved rheological and mechanical properties were prepared by using thermotropic phase transformations of metal soaps in polymers (calcium stearate/iPP). Morphology and thermal properties were studied using WAXS, DSC and SEM. Mechanical and rheological investigation showed significant reduction in process viscosity and substantial improvement in fracture toughness were attained. Effects of molecular architecture of metal soaps were investigated in PEEK (calcium stearate/PEEK and sodium stearate/PEEK). The selected compounds reduced the process viscosity due to the high temperature co-continuous morphology of metal soaps. Unlike the iPP system that incorporates spherical particles, interaction between PEEK and metal soaps resulted in two discrete and co-continuous phases of PEEK and the metal stearates. DMA and melt rheology exhibited that sodium stearate/PEEK composites are stiffer. Effective moduli of secondary metal stearate phase were calculated using different composite theories, which suggested bicontinuous morphology to the metal soaps in PEEK. Use of low molecular weight crystallizable solvents was investigated in reactive systems. Formation of anisotropic reinforcements was evaluated using dimethyl sulfone (DMS) as the crystallizable diluent and diglycidyl ether of bisphenol-A (DGEBA)/m-phenylene diamine (mPDA) material system as the epoxy thermoset. Miscible blends of DMS and DGEBA/mPDA form homogenous mixtures that undergo polymerization induced phase separation, once the DGEBA oligomers react with mPDA. The effect of the competition between the crystallization and phase separation of DMS resulted in nano-wires to micro-scale fiber-like crystals that were generated by adjusting the reaction temperature and DMS concentration.

Tin Sulfide Phase Exploration: Dependence of Optoelectronic Properties on Microstructural Growth and Chemical Variations in Thin Film Material

NASA Astrophysics Data System (ADS)

Banai, Rona Elinor

Herzenbergite tin (II) monosulfide (alpha-SnS) is of growing interest as a photovoltaic material because of its interesting optoelectronic properties and Earth abundance. It has several stable phases due to the dual valency of tin. As a layered material, alpha-SnS has the ability to form varying microstructure with differing properties. For this dissertation, films were RF sputtered from a SnS and SnS2 target to produce films with varying microstructure. Growth of high energy phases includin beta-SnS and amorphous SnS2 were possible through sputtering. Films of mixed or strained phase resulted from both targets. Pure phase alpha-SnS was made by annealing amorphous SnS2 films. Microstructure was measured using grazing incidence XRD and field emission SEM. The impact of microstructure was seen for both optical and electronic properties. Films were evaluated using spectroscopic ellipsometry as well as unpolarized UV-Vis transmission and reflection measurements. Optical modeling of the films is sufficient for developing models corresponding to specific microstructure, enabling it to be an inexpensive tool for studying the material. Absorption coefficient and band gap were also derived for these films. Films deposited with the SnS target had resistivity values up to 20,000 O-cm. Annealing of amorphous films deposited from the SnS2 target resulted in alpha-SnS films with much lower resistivity (<50 O-cm) values. This method for producing alpha-SnS offered better control of the phase, microstructure and therefore optoelectronic properties. While SnS films made from either target were typically p-type, sputtering of the SnS2 target with substrate heating resulted in n-type SnSx of a potentially new phase similar to SnS2 but with a 2:3 tin-to-sulfur ratio. Resistivity of those films typically ranged from 1 to 40 O-cm. Both p- and n-type films made from the SnS2 target had high carrier concentration of 10 17 to 1020 cm-3, but films had low Hall mobility such that conductivity type was not determined. Titanium, molybdenum, and aluminum contacts were tested for Ohmic and Schottky behavior using transmission line measurements. The complexity of its microstructure and flexibility in formation of varying phase and altered phase presents challenges to its use as a PV absorber.

Charge transport mechanism analysis of Al/CdS:Sr{sup 2+}/ITO device under dark and light

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

Datta, Joydeep; Das, Mrinmay; Dey, Arka

2016-05-06

In this study, we have synthesized CdS:Sr{sup 2+} by hydrothermal technique. Material property has been studied by X-ray diffraction (XRD), Scanning electron microscope (SEM) and UV-vis absorption spectroscopy. XRD data revealed that there are mixed phases of CdS and SrS in the synthesized sample. The optical band gap of the material was estimated as 3.15 eV from UV-vis data. The synthesized material has been applied in metal-semiconductor device and transport properties have been analyzed by measuring current–voltage characteristics under dark and light conditions at room temperature. Variation in different device parameters like ideality factor, barrier height and series resistance ofmore » Al/CdS:Sr{sup 2+}/ITO device were analyzed by using Cheung’s function.« less

Interior Structure of Ceres Artist Concept

NASA Image and Video Library

2016-08-03

This artist's concept shows a diagram of how the inside of Ceres could be structured, based on data about the dwarf planet's gravity field from NASA's Dawn mission. Using information about Ceres' gravity and topography, scientists found that Ceres is "differentiated," which means that it has compositionally distinct layers at different depths. The densest layer is at the core, which scientists suspect is made of hydrated silicates. Above that is a volatile-rich shell, topped with a crust of mixed materials. This research teaches scientists about what internal processes could have occurred during the early history of Ceres. It appears that, during a heating phase early in the history of Ceres, water and other light materials partially separated from rock. These light materials and water then rose to the outer layer of Ceres. http://photojournal.jpl.nasa.gov/catalog/PIA20867

Photoreduction of CO{sub 2} by TiO{sub 2} nanocomposites synthesized through reactive direct current magnetron sputter deposition.

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

Chen, L.; Graham, M. E.; Li, G.

The photoreduction of CO{sub 2} into methane provides a carbon-neutral energy alternative to fossil fuels, but its feasibility requires improvements in the photo-efficiency of materials tailored to this reaction. We hypothesize that mixed phase TiO{sub 2} nano-materials with high interfacial densities are extremely active photocatalysts well suited to solar fuel production by reducing CO{sub 2} to methane and shifting to visible light response. Mixed phase TiO{sub 2} films were synthesized by direct current (DC) magnetron sputtering and characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Bundles of anatase-rutile nano-columns havingmore » high densities of two kinds of interfaces (those among the bundles and those between the columns) are fabricated. Films sputtered at a low deposition angle showed the highest methane yield, compared to TiO{sub 2} fabricated under other sputtering conditions and commercial standard Degussa P25 under UV irradiation. The yield of methane could be significantly increased ({approx} 12% CO{sub 2} conversion) by increasing the CO{sub 2} to water ratio and temperature (< 100 C) as a combined effect. These films also displayed a light response strongly shifted into the visible range. This is explained by the creation of non-stoichiometric titania films having unique features that we can potentially tailor to the solar energy applications.« less

Integrated lunar materials manufacturing process

NASA Technical Reports Server (NTRS)

Gibson, Michael A. (Inventor); Knudsen, Christian W. (Inventor)

1990-01-01

A manufacturing plant and process for production of oxygen on the moon uses lunar minerals as feed and a minimum of earth-imported, process materials. Lunar feed stocks are hydrogen-reducible minerals, ilmenite and lunar agglutinates occurring in numerous, explored locations mixed with other minerals in the pulverized surface layer of lunar soil known as regolith. Ilmenite (FeTiO.sub.3) and agglutinates contain ferrous (Fe.sup.+2) iron reducible by hydrogen to yield H.sub.2 O and metallic Fe at about 700.degree.-1,200.degree. C. The H.sub.2 O is electrolyzed in gas phase to yield H.sub.2 for recycle and O.sub.2 for storage and use. Hydrogen losses to lunar vacuum are minimized, with no net hydrogen (or any other earth-derived reagent) consumption except for small leaks. Feed minerals are surface-mined by front shovels and transported in trucks to the processing area. The machines are manned or robotic. Ilmenite and agglutinates occur mixed with silicate minerals which are not hydrogen-reducible at 700.degree.-1,200.degree. C. and consequently are separated and concentrated before feeding to the oxygen generation process. Solids rejected from the separation step and reduced solids from the oxygen process are returned to the mine area. The plant is powered by nuclear or solar power generators. Vapor-phase water electrolysis, a staged, countercurrent, fluidized bed reduction reactor and a radio-frequency-driven ceramic gas heater are used to improve thermal efficiency.

Measurement of material nonlinearity using surface acoustic wave parametric interaction and laser ultrasonics.

PubMed

Stratoudaki, Theodosia; Ellwood, Robert; Sharples, Steve; Clark, Matthew; Somekh, Michael G; Collison, Ian J

2011-04-01

A dual frequency mixing technique has been developed for measuring velocity changes caused by material nonlinearity. The technique is based on the parametric interaction between two surface acoustic waves (SAWs): The low frequency pump SAW generated by a transducer and the high frequency probe SAW generated and detected using laser ultrasonics. The pump SAW stresses the material under the probe SAW. The stress (typically <5 MPa) is controlled by varying the timing between the pump and probe waves. The nonlinear interaction is measured as a phase modulation of the probe SAW and equated to a velocity change. The velocity-stress relationship is used as a measure of material nonlinearity. Experiments were conducted to observe the pump-probe interaction by changing the pump frequency and compare the nonlinear response of aluminum and fused silica. Experiments showed these two materials had opposite nonlinear responses, consistent with previously published data. The technique could be applied to life-time predictions of engineered components by measuring changes in nonlinear response caused by fatigue.

Data on volatile compounds in fermented materials used for salmon fish sauce production.

PubMed

Nakano, Mitsutoshi; Sagane, Yoshimasa; Koizumi, Ryosuke; Nakazawa, Yozo; Yamazaki, Masao; Watanabe, Toshihiro; Takano, Katsumi; Sato, Hiroaki

2018-02-01

This article describes the analysis of volatile compounds in fermented materials used for salmon fish sauce production via gas chromatography/mass spectrometry (GC/MS). Ten types of fish sauces were produced from raw salmon materials, including various proportions of flesh, viscera, inedible portion (heads, fins, and backbones), and soft roe, by mixing them with salt and allowing them to ferment for up to three months. The volatile compounds were captured by a solid-phase microextraction method and then applied to GC/MS for separation and identification of the compounds in the fish sauce products. The number of volatile compounds identified in the starting materials varied from 15 to 29 depending on the ingredients. The number of compounds in the final fish sauce products was reduced by 3.4-94.7% of that in the original material. The retention times and names of the identified compounds, as well as their relative peak areas, are provided in a Microsoft Excel Worksheet.

Process for preparing energetic materials

DOEpatents

Simpson, Randall L [Livermore, CA; Lee, Ronald S [Livermore, CA; Tillotson, Thomas M [Tracy, CA; Hrubesh, Lawrence W [Pleasanton, CA; Swansiger, Rosalind W [Livermore, CA; Fox, Glenn A [Livermore, CA

2011-12-13

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Sol-Gel Manufactured Energetic Materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Sol-gel manufactured energetic materials

DOEpatents

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2003-12-23

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

The properties of optimal two-dimensional phononic crystals with different material contrasts

NASA Astrophysics Data System (ADS)

Liu, Zong-Fa; Wu, Bin; He, Cun-Fu

2016-09-01

By modifying the spatial distribution of constituent material phases, phononic crystals (PnCs) can be designed to exhibit band gaps within which sound and vibration cannot propagate. In this paper, the developed topology optimization method (TOM), based on genetic algorithms (GAs) and the finite element method (FEM), is proposed to design two-dimensional (2D) solid PnC structures composed of two contrasting elastic materials. The PnCs have the lowest order band gap that is the third band gap for the coupled mode, the first band gap for the shear mode or the XY 34 Z band gap for the mixed mode. Moreover, the effects of the ratios of contrasting material properties on the optimal layout of unit cells and the corresponding phononic band gaps (PBGs) are investigated. The results indicate that the topology of the optimal PnCs and corresponding band gaps varies with the change of material contrasts. The law can be used for the rapid design of desired PnC structures.

Effect of phase transformation on optical and dielectric properties of zirconium oxide nanoparticles

NASA Astrophysics Data System (ADS)

Chintaparty, Rajababu; Palagiri, Bhavani; Reddy Nagireddy, Ramamanohar; subbha Reddy Imma Reddy, Venkata

2015-09-01

Zirconium oxide nanoparticle (ZrO2) is synthesized by the hydrothermal method at different calcination temperatures. The structural analysis is carried out by X-ray diffraction and Raman spectra. The sample prepared at 400 °C and 1100 °C showed the cubic and monoclinic phase, respectively, and the sample calcined at 600 °C and 800 °C showed the mixed phase with co-existence of cubic and monoclinic phases. Furthermore, the morphology and particle size of these samples were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The band gap estimated from UV-Vis spectra of ZrO2 (zirconia) nanocrystalline materials calcined at different temperatures from 400 °C to 1100 °C was in the range of 2.6-4.2 eV. The frequency dependence of dielectric constant and dielectric loss was investigated at room temperature. The low frequency region of dielectric constant is attributed to space charge effects.

Yb-doped large-mode-area laser fiber fabricated by halide-gas-phase-doping technique

NASA Astrophysics Data System (ADS)

Peng, Kun; Wang, Yuying; Ni, Li; Wang, Zhen; Gao, Cong; Zhan, Huan; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

2015-06-01

In this manuscript, we designed a rare-earth-halide gas-phase-doping setup to fabricate a large-mode-area fiber for high power laser applications. YbCl3 and AlCl3 halides are evaporated, carried respectively and finally mixed with usual host gas material SiCl4 at the hot zone of MCVD system. Owing to the all-gas-phasing reaction process and environment, the home-made Yb-doped fiber preform has a homogeneous large core and modulated refractive index profile to keep high beam quality. The drawn fiber core has a small numerical aperture of 0.07 and high Yb concentration of 9500 ppm. By using a master oscillator power amplifier system, nearly kW-level (951 W) laser output power was obtained with a slope efficiency of 83.3% at 1063.8 nm, indicating the competition and potential of the halide-gas-phase-doping technique for high power laser fiber fabrication.